From 83a26e1d57e804c07f1391308f6d871a2614f9ba Mon Sep 17 00:00:00 2001 From: nsz Date: Mon, 4 Jul 2011 03:59:44 +0200 Subject: [PATCH] remove old c1x draft --- n1516.html | 26869 --------------------------------------------------- n1516.txt | 26867 -------------------------------------------------- 2 files changed, 53736 deletions(-) delete mode 100644 n1516.html delete mode 100644 n1516.txt diff --git a/n1516.html b/n1516.html deleted file mode 100644 index 50b0914..0000000 --- a/n1516.html +++ /dev/null @@ -1,26869 +0,0 @@ -N1516 Committee Draft -- October 4, 2010 ISO/IEC 9899:201x
-N1516                     Committee Draft -- October 4, 2010          ISO/IEC 9899:201x
-
-
-
-
-INTERNATIONAL STANDARD                         (C)ISO/IEC              ISO/IEC 9899:201x
-
-
-
-
-Programming languages -- C
-
-
-                                       ABSTRACT
-
-
-
-                     (Cover sheet to be provided by ISO Secretariat.)
-
-This International Standard specifies the form and establishes the interpretation of
-programs expressed in the programming language C. Its purpose is to promote
-portability, reliability, maintainability, and efficient execution of C language programs on
-a variety of computing systems.
-
-Clauses are included that detail the C language itself and the contents of the C language
-execution library. Annexes summarize aspects of both of them, and enumerate factors
-that influence the portability of C programs.
-
-Although this International Standard is intended to guide knowledgeable C language
-programmers as well as implementors of C language translation systems, the document
-itself is not designed to serve as a tutorial.
-
-Recipients of this draft are invited to submit, with their comments, notification of any
-relevant patent rights of which they are aware and to provide supporting documentation.
-
-Changes from the previous draft (N1494) are indicated by ''diff marks'' in the right
-margin: deleted text is marked with ''*'', new or changed text with '' ''.
-
-
-
-
-[page i]
-
-
-
-[page ii]
-
-Contents
-Foreword       . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                 xiii
-Introduction    . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
-1. Scope       . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                   1
-2. Normative references    . . . . . . . . . . . . . . . . . . . . . . .                                   2
-3. Terms, definitions, and symbols   . . . . . . . . . . . . . . . . . . .                                  3
-4. Conformance       . . . . . . . . . . . . . . . . . . . . . . . . . .                                   8
-5. Environment    . . . . . . . . . . .       . .   .   .   .   .   .   .   .    .   .   .   .   .   .    10
-   5.1 Conceptual models       . . . . . .    . .   .   .   .   .   .   .   .    .   .   .   .   .   .    10
-        5.1.1  Translation environment .      . .   .   .   .   .   .   .   .    .   .   .   .   .   .    10
-        5.1.2  Execution environments     .   . .   .   .   .   .   .   .   .    .   .   .   .   .   .    12
-   5.2 Environmental considerations    . .    . .   .   .   .   .   .   .   .    .   .   .   .   .   .    22
-        5.2.1  Character sets    . . . . .    . .   .   .   .   .   .   .   .    .   .   .   .   .   .    22
-        5.2.2  Character display semantics      .   .   .   .   .   .   .   .    .   .   .   .   .   .    24
-        5.2.3  Signals and interrupts . .     . .   .   .   .   .   .   .   .    .   .   .   .   .   .    25
-        5.2.4  Environmental limits    . .    . .   .   .   .   .   .   .   .    .   .   .   .   .   .    25
-6. Language . . . . . . . . . . . . . . . .             .   .   .   .   .   .    .   .   .   .   .   .    35
-   6.1 Notation . . . . . . . . . . . . . .             .   .   .   .   .   .    .   .   .   .   .   .    35
-   6.2 Concepts       . . . . . . . . . . . . .         .   .   .   .   .   .    .   .   .   .   .   .    35
-        6.2.1   Scopes of identifiers     . . . . .      .   .   .   .   .   .    .   .   .   .   .   .    35
-        6.2.2   Linkages of identifiers . . . . .        .   .   .   .   .   .    .   .   .   .   .   .    36
-        6.2.3   Name spaces of identifiers      . . .    .   .   .   .   .   .    .   .   .   .   .   .    37
-        6.2.4   Storage durations of objects     . .    .   .   .   .   .   .    .   .   .   .   .   .    38
-        6.2.5   Types       . . . . . . . . . . .       .   .   .   .   .   .    .   .   .   .   .   .    39
-        6.2.6   Representations of types . . . .        .   .   .   .   .   .    .   .   .   .   .   .    44
-        6.2.7   Compatible type and composite type          .   .   .   .   .    .   .   .   .   .   .    47
-        6.2.8   Alignment of objects     . . . . .      .   .   .   .   .   .    .   .   .   .   .   .    48
-   6.3 Conversions       . . . . . . . . . . . .        .   .   .   .   .   .    .   .   .   .   .   .    50
-        6.3.1   Arithmetic operands      . . . . .      .   .   .   .   .   .    .   .   .   .   .   .    50
-        6.3.2   Other operands       . . . . . . .      .   .   .   .   .   .    .   .   .   .   .   .    54
-   6.4 Lexical elements       . . . . . . . . . .       .   .   .   .   .   .    .   .   .   .   .   .    57
-        6.4.1   Keywords . . . . . . . . . .            .   .   .   .   .   .    .   .   .   .   .   .    58
-        6.4.2   Identifiers . . . . . . . . . .          .   .   .   .   .   .    .   .   .   .   .   .    59
-        6.4.3   Universal character names      . . .    .   .   .   .   .   .    .   .   .   .   .   .    61
-        6.4.4   Constants . . . . . . . . . .           .   .   .   .   .   .    .   .   .   .   .   .    62
-        6.4.5   String literals   . . . . . . . .       .   .   .   .   .   .    .   .   .   .   .   .    70
-        6.4.6   Punctuators . . . . . . . . .           .   .   .   .   .   .    .   .   .   .   .   .    72
-        6.4.7   Header names      . . . . . . . .       .   .   .   .   .   .    .   .   .   .   .   .    73
-        6.4.8   Preprocessing numbers        . . . .    .   .   .   .   .   .    .   .   .   .   .   .    74
-        6.4.9   Comments        . . . . . . . . .       .   .   .   .   .   .    .   .   .   .   .   .    75
-
-
-[page iii]
-
-     6.5  Expressions      . . . . . . . . . .     .   .   .   .   .   .   .   .   .   .   .   .   .   .    76
-          6.5.1   Primary expressions      . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    78
-          6.5.2   Postfix operators . . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .    79
-          6.5.3   Unary operators      . . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    88
-          6.5.4   Cast operators . . . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .    91
-          6.5.5   Multiplicative operators   . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    92
-          6.5.6   Additive operators     . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    92
-          6.5.7   Bitwise shift operators . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .    94
-          6.5.8   Relational operators . . . .     .   .   .   .   .   .   .   .   .   .   .   .   .   .    95
-          6.5.9   Equality operators     . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    96
-          6.5.10 Bitwise AND operator . . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .    97
-          6.5.11 Bitwise exclusive OR operator         .   .   .   .   .   .   .   .   .   .   .   .   .    98
-          6.5.12 Bitwise inclusive OR operator     .   .   .   .   .   .   .   .   .   .   .   .   .   .    98
-          6.5.13 Logical AND operator . . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .    99
-          6.5.14 Logical OR operator       . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    99
-          6.5.15 Conditional operator      . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   100
-          6.5.16 Assignment operators . . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .   101
-          6.5.17 Comma operator . . . . .          .   .   .   .   .   .   .   .   .   .   .   .   .   .   104
-     6.6 Constant expressions . . . . . . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .   105
-     6.7 Declarations      . . . . . . . . . .     .   .   .   .   .   .   .   .   .   .   .   .   .   .   107
-          6.7.1   Storage-class specifiers    . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   108
-          6.7.2   Type specifiers . . . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   109
-          6.7.3   Type qualifiers . . . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   119
-          6.7.4   Function specifiers     . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   123
-          6.7.5   Alignment specifier . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   125
-          6.7.6   Declarators     . . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   126
-          6.7.7   Type names . . . . . . .         .   .   .   .   .   .   .   .   .   .   .   .   .   .   134
-          6.7.8   Type definitions      . . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   135
-          6.7.9   Initialization    . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   137
-          6.7.10 Static assertions     . . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   143
-     6.8 Statements and blocks      . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   144
-          6.8.1   Labeled statements     . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   144
-          6.8.2   Compound statement       . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   145
-          6.8.3   Expression and null statements       .   .   .   .   .   .   .   .   .   .   .   .   .   145
-          6.8.4   Selection statements     . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   146
-          6.8.5   Iteration statements . . . .     .   .   .   .   .   .   .   .   .   .   .   .   .   .   148
-          6.8.6   Jump statements      . . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   149
-     6.9 External definitions      . . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   153
-          6.9.1   Function definitions . . . .      .   .   .   .   .   .   .   .   .   .   .   .   .   .   154
-          6.9.2   External object definitions   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   156
-     6.10 Preprocessing directives     . . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   158
-          6.10.1 Conditional inclusion     . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   160
-          6.10.2 Source file inclusion      . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   162
-          6.10.3 Macro replacement . . . .         .   .   .   .   .   .   .   .   .   .   .   .   .   .   164
-
-
-[page iv]
-
-       6.10.4 Line control . . . . . .        .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   171
-       6.10.5 Error directive . . . . .       .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   172
-       6.10.6 Pragma directive . . . .        .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   172
-       6.10.7 Null directive      . . . . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   173
-       6.10.8 Predefined macro names .         .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   173
-       6.10.9 Pragma operator       . . . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   175
-  6.11 Future language directions     . . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.1 Floating types      . . . . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.2 Linkages of identifiers . .      .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.3 External names        . . . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.4 Character escape sequences          .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.5 Storage-class specifiers     .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.6 Function declarators      . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.7 Function definitions . . .       .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.8 Pragma directives       . . .   .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-       6.11.9 Predefined macro names .         .   .   .   .   .   .   .   .   .    .   .   .   .   .   .   177
-7. Library . . . . . . . . . . . . . . . . . .                .   .   .   .   .    .   .   .   .   .   .   178
-   7.1 Introduction     . . . . . . . . . . . . .             .   .   .   .   .    .   .   .   .   .   .   178
-         7.1.1 Definitions of terms . . . . . . .              .   .   .   .   .    .   .   .   .   .   .   178
-         7.1.2 Standard headers . . . . . . . .               .   .   .   .   .    .   .   .   .   .   .   179
-         7.1.3 Reserved identifiers . . . . . . .              .   .   .   .   .    .   .   .   .   .   .   180
-         7.1.4 Use of library functions    . . . . .          .   .   .   .   .    .   .   .   .   .   .   181
-   7.2 Diagnostics <assert.h>          . . . . . . .          .   .   .   .   .    .   .   .   .   .   .   184
-         7.2.1 Program diagnostics       . . . . . .          .   .   .   .   .    .   .   .   .   .   .   184
-   7.3 Complex arithmetic <complex.h>           . . .         .   .   .   .   .    .   .   .   .   .   .   186
-         7.3.1 Introduction . . . . . . . . . .               .   .   .   .   .    .   .   .   .   .   .   186
-         7.3.2 Conventions . . . . . . . . . .                .   .   .   .   .    .   .   .   .   .   .   187
-         7.3.3 Branch cuts . . . . . . . . . .                .   .   .   .   .    .   .   .   .   .   .   187
-         7.3.4 The CX_LIMITED_RANGE pragma                    .   .   .   .   .    .   .   .   .   .   .   187
-         7.3.5 Trigonometric functions . . . . .              .   .   .   .   .    .   .   .   .   .   .   188
-         7.3.6 Hyperbolic functions      . . . . . .          .   .   .   .   .    .   .   .   .   .   .   190
-         7.3.7 Exponential and logarithmic functions              .   .   .   .    .   .   .   .   .   .   192
-         7.3.8 Power and absolute-value functions             .   .   .   .   .    .   .   .   .   .   .   193
-         7.3.9 Manipulation functions      . . . . .          .   .   .   .   .    .   .   .   .   .   .   194
-   7.4 Character handling <ctype.h> . . . . .                 .   .   .   .   .    .   .   .   .   .   .   198
-         7.4.1 Character classification functions    .         .   .   .   .   .    .   .   .   .   .   .   198
-         7.4.2 Character case mapping functions     .         .   .   .   .   .    .   .   .   .   .   .   201
-   7.5 Errors <errno.h>         . . . . . . . . . .           .   .   .   .   .    .   .   .   .   .   .   203
-   7.6 Floating-point environment <fenv.h>        . .         .   .   .   .   .    .   .   .   .   .   .   204
-         7.6.1 The FENV_ACCESS pragma           . . .         .   .   .   .   .    .   .   .   .   .   .   206
-         7.6.2 Floating-point exceptions      . . . .         .   .   .   .   .    .   .   .   .   .   .   207
-         7.6.3 Rounding . . . . . . . . . . .                 .   .   .   .   .    .   .   .   .   .   .   210
-         7.6.4 Environment        . . . . . . . . .           .   .   .   .   .    .   .   .   .   .   .   211
-   7.7 Characteristics of floating types <float.h>             .   .   .   .   .    .   .   .   .   .   .   214
-
-[page v]
-
-     7.8    Format conversion of integer types <inttypes.h> . . . .           .   .   .   .   215
-            7.8.1    Macros for format specifiers      . . . . . . . . . .     .   .   .   .   215
-            7.8.2    Functions for greatest-width integer types   . . . . .   .   .   .   .   216
-     7.9    Alternative spellings <iso646.h> . . . . . . . . . . .            .   .   .   .   219
-     7.10   Sizes of integer types <limits.h>         . . . . . . . . . .     .   .   .   .   220
-     7.11   Localization <locale.h> . . . . . . . . . . . . . .               .   .   .   .   221
-            7.11.1 Locale control . . . . . . . . . . . . . . . .             .   .   .   .   222
-            7.11.2 Numeric formatting convention inquiry . . . . . .          .   .   .   .   223
-     7.12   Mathematics <math.h> . . . . . . . . . . . . . . .                .   .   .   .   229
-            7.12.1 Treatment of error conditions . . . . . . . . . .          .   .   .   .   231
-            7.12.2 The FP_CONTRACT pragma             . . . . . . . . . .     .   .   .   .   233
-            7.12.3 Classification macros       . . . . . . . . . . . . .       .   .   .   .   233
-            7.12.4 Trigonometric functions . . . . . . . . . . . .            .   .   .   .   236
-            7.12.5 Hyperbolic functions       . . . . . . . . . . . . .       .   .   .   .   238
-            7.12.6 Exponential and logarithmic functions        . . . . . .   .   .   .   .   240
-            7.12.7 Power and absolute-value functions         . . . . . . .   .   .   .   .   245
-            7.12.8 Error and gamma functions . . . . . . . . . . .            .   .   .   .   247
-            7.12.9 Nearest integer functions . . . . . . . . . . . .          .   .   .   .   249
-            7.12.10 Remainder functions       . . . . . . . . . . . . .       .   .   .   .   252
-            7.12.11 Manipulation functions       . . . . . . . . . . . .      .   .   .   .   253
-            7.12.12 Maximum, minimum, and positive difference functions           .   .   .   255
-            7.12.13 Floating multiply-add . . . . . . . . . . . . .           .   .   .   .   256
-            7.12.14 Comparison macros . . . . . . . . . . . . . .             .   .   .   .   257
-     7.13   Nonlocal jumps <setjmp.h>            . . . . . . . . . . . .      .   .   .   .   260
-            7.13.1 Save calling environment         . . . . . . . . . . .     .   .   .   .   260
-            7.13.2 Restore calling environment        . . . . . . . . . .     .   .   .   .   261
-     7.14   Signal handling <signal.h> . . . . . . . . . . . . .              .   .   .   .   263
-            7.14.1 Specify signal handling       . . . . . . . . . . . .      .   .   .   .   264
-            7.14.2 Send signal      . . . . . . . . . . . . . . . . .         .   .   .   .   265
-     7.15   Alignment <stdalign.h>            . . . . . . . . . . . . .       .   .   .   .   266
-     7.16   Variable arguments <stdarg.h>           . . . . . . . . . . .     .   .   .   .   267
-            7.16.1 Variable argument list access macros . . . . . . .         .   .   .   .   267
-     7.17   Atomics <stdatomic.h> . . . . . . . . . . . . . .                 .   .   .   .   271
-            7.17.1 Introduction . . . . . . . . . . . . . . . . .             .   .   .   .   271
-            7.17.2 Initialization      . . . . . . . . . . . . . . . .        .   .   .   .   272
-            7.17.3 Order and consistency . . . . . . . . . . . . .            .   .   .   .   273
-            7.17.4 Fences . . . . . . . . . . . . . . . . . . .               .   .   .   .   276
-            7.17.5 Lock-free property       . . . . . . . . . . . . . .       .   .   .   .   277
-            7.17.6 Atomic integer and address types         . . . . . . . .   .   .   .   .   278
-            7.17.7 Operations on atomic types . . . . . . . . . . .           .   .   .   .   280
-            7.17.8 Atomic flag type and operations . . . . . . . . .           .   .   .   .   283
-     7.18   Boolean type and values <stdbool.h>             . . . . . . . .   .   .   .   .   285
-     7.19   Common definitions <stddef.h> . . . . . . . . . . .                .   .   .   .   286
-     7.20   Integer types <stdint.h> . . . . . . . . . . . . . .              .   .   .   .   288
-
-
-[page vi]
-
-         7.20.1 Integer types      . . . . . . . . . . . .      .   .    .   .   .   .   .   .   288
-         7.20.2 Limits of specified-width integer types    . .   .   .    .   .   .   .   .   .   290
-         7.20.3 Limits of other integer types    . . . . . .    .   .    .   .   .   .   .   .   292
-         7.20.4 Macros for integer constants     . . . . . .    .   .    .   .   .   .   .   .   293
-  7.21   Input/output <stdio.h>         . . . . . . . . . .     .   .    .   .   .   .   .   .   295
-         7.21.1 Introduction . . . . . . . . . . . . .          .   .    .   .   .   .   .   .   295
-         7.21.2 Streams       . . . . . . . . . . . . . .       .   .    .   .   .   .   .   .   297
-         7.21.3 Files . . . . . . . . . . . . . . . .           .   .    .   .   .   .   .   .   299
-         7.21.4 Operations on files      . . . . . . . . . .     .   .    .   .   .   .   .   .   301
-         7.21.5 File access functions     . . . . . . . . .     .   .    .   .   .   .   .   .   303
-         7.21.6 Formatted input/output functions     . . . .    .   .    .   .   .   .   .   .   308
-         7.21.7 Character input/output functions . . . . .      .   .    .   .   .   .   .   .   329
-         7.21.8 Direct input/output functions    . . . . . .    .   .    .   .   .   .   .   .   333
-         7.21.9 File positioning functions     . . . . . . .    .   .    .   .   .   .   .   .   334
-         7.21.10 Error-handling functions . . . . . . . .       .   .    .   .   .   .   .   .   337
-  7.22   General utilities <stdlib.h>        . . . . . . . .    .   .    .   .   .   .   .   .   339
-         7.22.1 Numeric conversion functions . . . . . .        .   .    .   .   .   .   .   .   340
-         7.22.2 Pseudo-random sequence generation functions         .    .   .   .   .   .   .   345
-         7.22.3 Memory management functions . . . . .           .   .    .   .   .   .   .   .   346
-         7.22.4 Communication with the environment        . .   .   .    .   .   .   .   .   .   348
-         7.22.5 Searching and sorting utilities . . . . . .     .   .    .   .   .   .   .   .   352
-         7.22.6 Integer arithmetic functions     . . . . . .    .   .    .   .   .   .   .   .   354
-         7.22.7 Multibyte/wide character conversion functions       .    .   .   .   .   .   .   355
-         7.22.8 Multibyte/wide string conversion functions      .   .    .   .   .   .   .   .   357
-  7.23   String handling <string.h> . . . . . . . . .           .   .    .   .   .   .   .   .   359
-         7.23.1 String function conventions . . . . . . .       .   .    .   .   .   .   .   .   359
-         7.23.2 Copying functions       . . . . . . . . . .     .   .    .   .   .   .   .   .   359
-         7.23.3 Concatenation functions . . . . . . . .         .   .    .   .   .   .   .   .   361
-         7.23.4 Comparison functions . . . . . . . . .          .   .    .   .   .   .   .   .   362
-         7.23.5 Search functions      . . . . . . . . . . .     .   .    .   .   .   .   .   .   364
-         7.23.6 Miscellaneous functions . . . . . . . .         .   .    .   .   .   .   .   .   367
-  7.24   Type-generic math <tgmath.h>          . . . . . . .    .   .    .   .   .   .   .   .   369
-  7.25   Threads <threads.h>          . . . . . . . . . . .     .   .    .   .   .   .   .   .   372
-         7.25.1 Introduction . . . . . . . . . . . . .          .   .    .   .   .   .   .   .   372
-         7.25.2 Initialization functions . . . . . . . . .      .   .    .   .   .   .   .   .   374
-         7.25.3 Condition variable functions     . . . . . .    .   .    .   .   .   .   .   .   374
-         7.25.4 Mutex functions       . . . . . . . . . . .     .   .    .   .   .   .   .   .   376
-         7.25.5 Thread functions . . . . . . . . . . .          .   .    .   .   .   .   .   .   379
-         7.25.6 Thread-specific storage functions     . . . .    .   .    .   .   .   .   .   .   381
-         7.25.7 Time functions . . . . . . . . . . . .          .   .    .   .   .   .   .   .   383
-  7.26   Date and time <time.h>         . . . . . . . . . .     .   .    .   .   .   .   .   .   384
-         7.26.1 Components of time        . . . . . . . . .     .   .    .   .   .   .   .   .   384
-         7.26.2 Time manipulation functions      . . . . . .    .   .    .   .   .   .   .   .   385
-         7.26.3 Time conversion functions      . . . . . . .    .   .    .   .   .   .   .   .   387
-
-
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-
-   7.27 Unicode utilities <uchar.h> . . . . . . . . . . . . . .               . .     .   394
-        7.27.1 Restartable multibyte/wide character conversion functions        .     .   394
-   7.28 Extended multibyte and wide character utilities <wchar.h> . .         . .     .   398
-        7.28.1 Introduction . . . . . . . . . . . . . . . . . .               . .     .   398
-        7.28.2 Formatted wide character input/output functions       . . .    . .     .   399
-        7.28.3 Wide character input/output functions        . . . . . . .     . .     .   417
-        7.28.4 General wide string utilities     . . . . . . . . . . .        . .     .   421
-                 7.28.4.1 Wide string numeric conversion functions     . .    . .     .   422
-                 7.28.4.2 Wide string copying functions . . . . . . .         . .     .   426
-                 7.28.4.3 Wide string concatenation functions      . . . .    . .     .   428
-                 7.28.4.4 Wide string comparison functions      . . . . .     . .     .   429
-                 7.28.4.5 Wide string search functions      . . . . . . .     . .     .   431
-                 7.28.4.6 Miscellaneous functions      . . . . . . . . .      . .     .   435
-        7.28.5 Wide character time conversion functions       . . . . . .     . .     .   435
-        7.28.6 Extended multibyte/wide character conversion utilities .       . .     .   436
-                 7.28.6.1 Single-byte/wide character conversion functions     . .     .   437
-                 7.28.6.2 Conversion state functions     . . . . . . . .      . .     .   437
-                 7.28.6.3 Restartable multibyte/wide character conversion
-                           functions   . . . . . . . . . . . . . . .          . . . 438
-                 7.28.6.4 Restartable multibyte/wide string conversion
-                           functions   . . . . . . . . . . . . . . .          .   .   .   440
-   7.29 Wide character classification and mapping utilities <wctype.h>         .   .   .   443
-        7.29.1 Introduction . . . . . . . . . . . . . . . . . .               .   .   .   443
-        7.29.2 Wide character classification utilities . . . . . . . .         .   .   .   444
-                 7.29.2.1 Wide character classification functions     . . .    .   .   .   444
-                 7.29.2.2 Extensible wide character classification
-                           functions   . . . . . . . . . . . . . . .          . . . 447
-        7.29.3 Wide character case mapping utilities . . . . . . . .          . . . 449
-                 7.29.3.1 Wide character case mapping functions      . . .    . . . 449
-                 7.29.3.2 Extensible wide character case mapping
-                           functions   . . . . . . . . . . . . . . .          .   .   .   449
-   7.30 Future library directions    . . . . . . . . . . . . . . . .          .   .   .   451
-        7.30.1 Complex arithmetic <complex.h> . . . . . . . .                 .   .   .   451
-        7.30.2 Character handling <ctype.h>            . . . . . . . . .      .   .   .   451
-        7.30.3 Errors <errno.h>           . . . . . . . . . . . . . .         .   .   .   451
-        7.30.4 Format conversion of integer types <inttypes.h>            .   .   .   .   451
-        7.30.5 Localization <locale.h>           . . . . . . . . . . .        .   .   .   451
-        7.30.6 Signal handling <signal.h>           . . . . . . . . . .       .   .   .   451
-        7.30.7 Boolean type and values <stdbool.h>            . . . . . .     .   .   .   451
-        7.30.8 Integer types <stdint.h>          . . . . . . . . . . .        .   .   .   451
-        7.30.9 Input/output <stdio.h>          . . . . . . . . . . . .        .   .   .   452
-        7.30.10 General utilities <stdlib.h>        . . . . . . . . . .       .   .   .   452
-        7.30.11 String handling <string.h>          . . . . . . . . . .       .   .   .   452
-
-
-
-[page viii]
-
-        7.30.12 Extended multibyte and wide character utilities
-                <wchar.h>        . . . . . . . . . . . . . . . . . . . . 452
-        7.30.13 Wide character classification and mapping utilities
-                <wctype.h> . . . . . . . . . . . . . . . . . . . . 452
-Annex A (informative) Language syntax summary   . .       .    .   .   .    .   .   .   .   .   .   453
-  A.1 Lexical grammar       . . . . . . . . . . . .       .    .   .   .    .   .   .   .   .   .   453
-  A.2 Phrase structure grammar . . . . . . . . .          .    .   .   .    .   .   .   .   .   .   460
-  A.3 Preprocessing directives    . . . . . . . . .       .    .   .   .    .   .   .   .   .   .   468
-Annex B (informative) Library summary     . . . . . . . . . . . . .                     .   .   .   470
-  B.1 Diagnostics <assert.h>          . . . . . . . . . . . . . . .                     .   .   .   470
-  B.2 Complex <complex.h> . . . . . . . . . . . . . . . .                               .   .   .   470
-  B.3 Character handling <ctype.h> . . . . . . . . . . . . .                            .   .   .   472
-  B.4 Errors <errno.h>         . . . . . . . . . . . . . . . . . .                      .   .   .   472
-  B.5 Floating-point environment <fenv.h>          . . . . . . . . . .                  .   .   .   472
-  B.6 Characteristics of floating types <float.h> . . . . . . . .                        .   .   .   473
-  B.7 Format conversion of integer types <inttypes.h> . . . . .                         .   .   .   473
-  B.8 Alternative spellings <iso646.h> . . . . . . . . . . . .                          .   .   .   474
-  B.9 Sizes of integer types <limits.h>          . . . . . . . . . . .                  .   .   .   474
-  B.10 Localization <locale.h> . . . . . . . . . . . . . . .                            .   .   .   474
-  B.11 Mathematics <math.h> . . . . . . . . . . . . . . . .                             .   .   .   474
-  B.12 Nonlocal jumps <setjmp.h>          . . . . . . . . . . . . .                     .   .   .   479
-  B.13 Signal handling <signal.h> . . . . . . . . . . . . . .                           .   .   .   479
-  B.14 Alignment <stdalign.h>           . . . . . . . . . . . . . .                     .   .   .   480
-  B.15 Variable arguments <stdarg.h>         . . . . . . . . . . . .                    .   .   .   480
-  B.16 Atomics <stdatomic.h> . . . . . . . . . . . . . . .                              .   .   .   480
-  B.17 Boolean type and values <stdbool.h>           . . . . . . . . .                  .   .   .   482
-  B.18 Common definitions <stddef.h> . . . . . . . . . . . .                             .   .   .   482
-  B.19 Integer types <stdint.h> . . . . . . . . . . . . . . .                           .   .   .   482
-  B.20 Input/output <stdio.h>         . . . . . . . . . . . . . . .                     .   .   .   483
-  B.21 General utilities <stdlib.h>       . . . . . . . . . . . . .                     .   .   .   486
-  B.22 String handling <string.h> . . . . . . . . . . . . . .                           .   .   .   488
-  B.23 Type-generic math <tgmath.h>          . . . . . . . . . . . .                    .   .   .   490
-  B.24 Threads <threads.h>          . . . . . . . . . . . . . . . .                     .   .   .   490
-  B.25 Date and time <time.h>         . . . . . . . . . . . . . . .                     .   .   .   491
-  B.26 Unicode utilities <uchar.h> . . . . . . . . . . . . . .                          .   .   .   492
-  B.27 Extended multibyte/wide character utilities <wchar.h>     . . .                  .   .   .   492
-  B.28 Wide character classification and mapping utilities <wctype.h>                    .   .   .   497
-Annex C (informative) Sequence points     . . . . . . . . . . . . . . . . . 498
-Annex D (normative) Universal character names for identifiers           . . . . . . . 499
-Annex E (informative) Implementation limits        . . . . . . . . . . . . . . 501
-Annex F (normative) IEC 60559 floating-point arithmetic . . . . . . . . . . 503
-  F.1 Introduction     . . . . . . . . . . . . . . . . . . . . . . . . 503
-
-[page ix]
-
-    F.2    Types . . . . . . . . . . . . . . . . . . . . . . .                . .     .   .   503
-    F.3    Operators and functions       . . . . . . . . . . . . . . .        . .     .   .   504
-    F.4    Floating to integer conversion    . . . . . . . . . . . . .        . .     .   .   506
-    F.5    Binary-decimal conversion       . . . . . . . . . . . . . .        . .     .   .   506
-    F.6    The return statement . . . . . . . . . . . . . . . .               . .     .   .   507
-    F.7    Contracted expressions . . . . . . . . . . . . . . . .             . .     .   .   507
-    F.8    Floating-point environment      . . . . . . . . . . . . . .        . .     .   .   507
-    F.9    Optimization . . . . . . . . . . . . . . . . . . . .               . .     .   .   510
-    F.10   Mathematics <math.h> . . . . . . . . . . . . . . .                 . .     .   .   513
-           F.10.1 Trigonometric functions . . . . . . . . . . . .             . .     .   .   514
-           F.10.2 Hyperbolic functions       . . . . . . . . . . . . .        . .     .   .   516
-           F.10.3 Exponential and logarithmic functions    . . . . . .        . .     .   .   516
-           F.10.4 Power and absolute value functions     . . . . . . .        . .     .   .   519
-           F.10.5 Error and gamma functions . . . . . . . . . . .             . .     .   .   521
-           F.10.6 Nearest integer functions . . . . . . . . . . . .           . .     .   .   521
-           F.10.7 Remainder functions        . . . . . . . . . . . . .        . .     .   .   524
-           F.10.8 Manipulation functions       . . . . . . . . . . . .        . .     .   .   525
-           F.10.9 Maximum, minimum, and positive difference functions           .     .   .   525
-           F.10.10 Floating multiply-add . . . . . . . . . . . . .            . .     .   .   526
-           F.10.11 Comparison macros . . . . . . . . . . . . . .              . .     .   .   526
-Annex G (informative) IEC 60559-compatible complex arithmetic         .   .   .   .   .   .   527
-  G.1 Introduction      . . . . . . . . . . . . . . . . .         .   .   .   .   .   .   .   527
-  G.2 Types . . . . . . . . . . . . . . . . . . . .               .   .   .   .   .   .   .   527
-  G.3 Conventions       . . . . . . . . . . . . . . . . .         .   .   .   .   .   .   .   527
-  G.4 Conversions       . . . . . . . . . . . . . . . . .         .   .   .   .   .   .   .   528
-       G.4.1 Imaginary types      . . . . . . . . . . . .         .   .   .   .   .   .   .   528
-       G.4.2 Real and imaginary . . . . . . . . . . .             .   .   .   .   .   .   .   528
-       G.4.3 Imaginary and complex       . . . . . . . . .        .   .   .   .   .   .   .   528
-  G.5 Binary operators      . . . . . . . . . . . . . . .         .   .   .   .   .   .   .   528
-       G.5.1 Multiplicative operators    . . . . . . . . .        .   .   .   .   .   .   .   529
-       G.5.2 Additive operators     . . . . . . . . . . .         .   .   .   .   .   .   .   532
-  G.6 Complex arithmetic <complex.h>          . . . . . . .       .   .   .   .   .   .   .   532
-       G.6.1 Trigonometric functions . . . . . . . . .            .   .   .   .   .   .   .   534
-       G.6.2 Hyperbolic functions     . . . . . . . . . .         .   .   .   .   .   .   .   534
-       G.6.3 Exponential and logarithmic functions      . . .     .   .   .   .   .   .   .   538
-       G.6.4 Power and absolute-value functions      . . . .      .   .   .   .   .   .   .   539
-  G.7 Type-generic math <tgmath.h>          . . . . . . . .       .   .   .   .   .   .   .   540
-Annex H (informative) Language independent arithmetic . .     .   .   .   .   .   .   .   .   541
-  H.1 Introduction     . . . . . . . . . . . . . . . .        .   .   .   .   .   .   .   .   541
-  H.2 Types . . . . . . . . . . . . . . . . . . .             .   .   .   .   .   .   .   .   541
-  H.3 Notification      . . . . . . . . . . . . . . . .        .   .   .   .   .   .   .   .   545
-Annex I (informative) Common warnings       . . . . . . . . . . . . . . . . 547
-
-
-[page x]
-
-Annex J (informative) Portability issues    . . . .   .   .   .   .   .   .   .    .   .   .   .   .   .   549
-  J.1 Unspecified behavior . . . .           . . . .   .   .   .   .   .   .   .    .   .   .   .   .   .   549
-  J.2 Undefined behavior          . . . .    . . . .   .   .   .   .   .   .   .    .   .   .   .   .   .   552
-  J.3 Implementation-defined behavior          . . .   .   .   .   .   .   .   .    .   .   .   .   .   .   566
-  J.4 Locale-specific behavior         . .   . . . .   .   .   .   .   .   .   .    .   .   .   .   .   .   573
-  J.5 Common extensions          . . . .    . . . .   .   .   .   .   .   .   .    .   .   .   .   .   .   574
-Annex K (normative) Bounds-checking interfaces . . . . . . . . . .                             .   .   .   577
-  K.1 Background       . . . . . . . . . . . . . . . . . . . . .                               .   .   .   577
-  K.2 Scope . . . . . . . . . . . . . . . . . . . . . . . .                                    .   .   .   578
-  K.3 Library     . . . . . . . . . . . . . . . . . . . . . . .                                .   .   .   578
-       K.3.1 Introduction . . . . . . . . . . . . . . . . . .                                  .   .   .   578
-                K.3.1.1 Standard headers     . . . . . . . . . . . .                           .   .   .   578
-                K.3.1.2 Reserved identifiers     . . . . . . . . . . .                          .   .   .   579
-                K.3.1.3 Use of errno . . . . . . . . . . . . . .                               .   .   .   579
-                K.3.1.4 Runtime-constraint violations     . . . . . . .                        .   .   .   579
-       K.3.2 Errors <errno.h>           . . . . . . . . . . . . . .                            .   .   .   580
-       K.3.3 Common definitions <stddef.h>               . . . . . . . .                        .   .   .   580
-       K.3.4 Integer types <stdint.h>           . . . . . . . . . . .                          .   .   .   580
-       K.3.5 Input/output <stdio.h>          . . . . . . . . . . . .                           .   .   .   581
-                K.3.5.1 Operations on files      . . . . . . . . . . .                          .   .   .   581
-                K.3.5.2 File access functions . . . . . . . . . . .                            .   .   .   583
-                K.3.5.3 Formatted input/output functions . . . . . .                           .   .   .   586
-                K.3.5.4 Character input/output functions . . . . . .                           .   .   .   597
-       K.3.6 General utilities <stdlib.h>          . . . . . . . . . .                         .   .   .   599
-                K.3.6.1 Runtime-constraint handling       . . . . . . .                        .   .   .   599
-                K.3.6.2 Communication with the environment . . . .                             .   .   .   601
-                K.3.6.3 Searching and sorting utilities . . . . . . .                          .   .   .   602
-                K.3.6.4 Multibyte/wide character conversion functions                          .   .   .   605
-                K.3.6.5 Multibyte/wide string conversion functions . .                         .   .   .   606
-       K.3.7 String handling <string.h>            . . . . . . . . . .                         .   .   .   609
-                K.3.7.1 Copying functions       . . . . . . . . . . .                          .   .   .   609
-                K.3.7.2 Concatenation functions       . . . . . . . . .                        .   .   .   612
-                K.3.7.3 Search functions     . . . . . . . . . . . .                           .   .   .   615
-                K.3.7.4 Miscellaneous functions       . . . . . . . . .                        .   .   .   616
-       K.3.8 Date and time <time.h>          . . . . . . . . . . . .                           .   .   .   619
-                K.3.8.1 Components of time . . . . . . . . . . .                               .   .   .   619
-                K.3.8.2 Time conversion functions       . . . . . . . .                        .   .   .   619
-       K.3.9 Extended multibyte and wide character utilities
-                <wchar.h>        . . . . . . . . . . . . . . . . .                             . . . 622
-                K.3.9.1 Formatted wide character input/output functions                        . . . 623
-                K.3.9.2 General wide string utilities . . . . . . . .                          . . . 634
-                K.3.9.3 Extended multibyte/wide character conversion
-                        utilities . . . . . . . . . . . . . . . .                              . . . 642
-
-
-[page xi]
-
-Annex L (normative) Analyzability . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   647
-  L.1 Scope . . . . . . . . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   647
-  L.2 Definitions . . . . . . . . .      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   647
-  L.3 Requirements . . . . . . . .      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   648
-Bibliography   . . . . . . . . . . . . . . . . . . . . . . . . . . . 649
-Index    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
-
-
-
-
-[page xii] (Contents)
-
-    Foreword
-1   ISO (the International Organization for Standardization) and IEC (the International
-    Electrotechnical Commission) form the specialized system for worldwide
-    standardization. National bodies that are member of ISO or IEC participate in the
-    development of International Standards through technical committees established by the
-    respective organization to deal with particular fields of technical activity. ISO and IEC
-    technical committees collaborate in fields of mutual interest. Other international
-    organizations, governmental and non-governmental, in liaison with ISO and IEC, also
-    take part in the work.
-2   International Standards are drafted in accordance with the rules given in the ISO/IEC
-    Directives, Part 2. This International Standard was drafted in accordance with the fifth
-    edition (2004).
-3   In the field of information technology, ISO and IEC have established a joint technical
-    committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical
-    committee are circulated to national bodies for voting. Publication as an International
-    Standard requires approval by at least 75% of the national bodies casting a vote.
-4   Attention is drawn to the possibility that some of the elements of this document may be
-    the subject of patent rights. ISO and IEC shall not be held responsible for identifying any
-    or all such patent rights.
-5   This International Standard was prepared by Joint Technical Committee ISO/IEC JTC 1,
-    Information technology, Subcommittee SC 22, Programming languages, their
-    environments and system software interfaces. The Working Group responsible for this
-    standard (WG 14) maintains a site on the World Wide Web at http://www.open-
-    std.org/JTC1/SC22/WG14/ containing additional information relevant to this
-    standard such as a Rationale for many of the decisions made during its preparation and a
-    log of Defect Reports and Responses.
-6   This third edition cancels and replaces the second edition, ISO/IEC 9899:1999, as
-    corrected by ISO/IEC 9899:1999/Cor 1:2001, ISO/IEC 9899:1999/Cor 2:2004, and
-    ISO/IEC 9899:1999/Cor 3:2007. Major changes from the previous edition include:
-    -- conditional (optional) features (including some that were previously mandatory)
-    -- support for multiple threads of execution including an improved memory sequencing
-      model, atomic objects, and thread-local storage (<stdatomic.h> and
-      <threads.h>)
-    -- additional floating-point characteristic macros (<float.h>)
-    -- querying and specifying alignment of objects (<stdalign.h>, <stdlib.h>)
-    -- Unicode characters and           strings   (<uchar.h>)       (originally   specified    in
-      ISO/IEC TR 19769:2004)
-    -- type-generic expressions
-
-
-[page xiii] (Contents)
-
-    -- static assertions
-    -- anonymous structures and unions
-    -- no-return functions
-    -- macros to create complex numbers (<complex.h>)
-    -- support for opening files for exclusive access
-    -- removed the gets function (<stdio.h>)
-    -- added the aligned_alloc, at_quick_exit, and quick_exit functions
-      (<stdlib.h>)
-    -- (conditional) support for bounds-checking interfaces (originally specified in
-      ISO/IEC TR 24731-1:2007)
-    -- (conditional) support for analyzability
-7   Major changes in the second edition included:
-    -- restricted character set support via digraphs and <iso646.h> (originally specified
-      in AMD1)
-    -- wide character library support in <wchar.h> and <wctype.h> (originally
-      specified in AMD1)
-    -- more precise aliasing rules via effective type
-    -- restricted pointers
-    -- variable length arrays
-    -- flexible array members
-    -- static and type qualifiers in parameter array declarators
-    -- complex (and imaginary) support in <complex.h>
-    -- type-generic math macros in <tgmath.h>
-    -- the long long int type and library functions
-    -- increased minimum translation limits
-    -- additional floating-point characteristics in <float.h>
-    -- remove implicit int
-    -- reliable integer division
-    -- universal character names (\u and \U)
-    -- extended identifiers
-    -- hexadecimal floating-point constants and %a and %A printf/scanf conversion
-      specifiers
-
-
-
-[page xiv] (Contents)
-
--- compound literals
--- designated initializers
--- // comments
--- extended integer types and library functions in <inttypes.h> and <stdint.h>
--- remove implicit function declaration
--- preprocessor arithmetic done in intmax_t/uintmax_t
--- mixed declarations and code
--- new block scopes for selection and iteration statements
--- integer constant type rules
--- integer promotion rules
--- macros with a variable number of arguments
--- the vscanf family of functions in <stdio.h> and <wchar.h>
--- additional math library functions in <math.h>
--- treatment of error conditions by math library functions (math_errhandling)
--- floating-point environment access in <fenv.h>
--- IEC 60559 (also known as IEC 559 or IEEE arithmetic) support
--- trailing comma allowed in enum declaration
--- %lf conversion specifier allowed in printf
--- inline functions
--- the snprintf family of functions in <stdio.h>
--- boolean type in <stdbool.h>
--- idempotent type qualifiers
--- empty macro arguments
--- new structure type compatibility rules (tag compatibility)
--- additional predefined macro names
--- _Pragma preprocessing operator
--- standard pragmas
--- __func__ predefined identifier
--- va_copy macro
--- additional strftime conversion specifiers
--- LIA compatibility annex
-
-
-[page xv] (Contents)
-
-    -- deprecate ungetc at the beginning of a binary file
-    -- remove deprecation of aliased array parameters
-    -- conversion of array to pointer not limited to lvalues
-    -- relaxed constraints on aggregate and union initialization
-    -- relaxed restrictions on portable header names
-    -- return without expression not permitted in function that returns a value (and vice
-      versa)
-8   Annexes D, F, K, and L form a normative part of this standard; annexes A, B, C, E, G, H,
-    I, J, the bibliography, and the index are for information only. In accordance with Part 2 of
-    the ISO/IEC Directives, this foreword, the introduction, notes, footnotes, and examples
-    are also for information only.
-
-
-
-
-[page xvi] (Contents)
-
-    Introduction
-1   With the introduction of new devices and extended character sets, new features may be
-    added to this International Standard. Subclauses in the language and library clauses warn
-    implementors and programmers of usages which, though valid in themselves, may
-    conflict with future additions.
-2   Certain features are obsolescent, which means that they may be considered for
-    withdrawal in future revisions of this International Standard. They are retained because
-    of their widespread use, but their use in new implementations (for implementation
-    features) or new programs (for language [6.11] or library features [7.30]) is discouraged.
-3   This International Standard is divided into four major subdivisions:
-    -- preliminary elements (clauses 1-4);
-    -- the characteristics of environments that translate and execute C programs (clause 5);
-    -- the language syntax, constraints, and semantics (clause 6);
-    -- the library facilities (clause 7).
-4   Examples are provided to illustrate possible forms of the constructions described.
-    Footnotes are provided to emphasize consequences of the rules described in that
-    subclause or elsewhere in this International Standard. References are used to refer to
-    other related subclauses. Recommendations are provided to give advice or guidance to
-    implementors. Annexes provide additional information and summarize the information
-    contained in this International Standard. A bibliography lists documents that were
-    referred to during the preparation of the standard.
-5   The language clause (clause 6) is derived from ''The C Reference Manual''.
-6   The library clause (clause 7) is based on the 1984 /usr/group Standard.
-
-
-
-
-[page xvii] (Contents)
-
-
-
-[page xviii] (Contents)
-
-
-
-    Programming languages -- C
-
-
-
-    1. Scope
-1   This International Standard specifies the form and establishes the interpretation of
-    programs written in the C programming language.1) It specifies
-    -- the representation of C programs;
-    -- the syntax and constraints of the C language;
-    -- the semantic rules for interpreting C programs;
-    -- the representation of input data to be processed by C programs;
-    -- the representation of output data produced by C programs;
-    -- the restrictions and limits imposed by a conforming implementation of C.
-2   This International Standard does not specify
-    -- the mechanism by which C programs are transformed for use by a data-processing
-      system;
-    -- the mechanism by which C programs are invoked for use by a data-processing
-      system;
-    -- the mechanism by which input data are transformed for use by a C program;
-    -- the mechanism by which output data are transformed after being produced by a C
-      program;
-    -- the size or complexity of a program and its data that will exceed the capacity of any
-      specific data-processing system or the capacity of a particular processor;
-    -- all minimal requirements of a data-processing system that is capable of supporting a
-      conforming implementation.
-
-
-    1)   This International Standard is designed to promote the portability of C programs among a variety of
-         data-processing systems. It is intended for use by implementors and programmers.
-
-[page 1] (Contents)
-
-
-    2. Normative references
-1   The following referenced documents are indispensable for the application of this
-    document. For dated references, only the edition cited applies. For undated references,
-    the latest edition of the referenced document (including any amendments) applies.
-2   ISO 31-11:1992, Quantities and units -- Part 11: Mathematical signs and symbols for
-    use in the physical sciences and technology.
-3   ISO/IEC 646, Information technology -- ISO 7-bit coded character set for information
-    interchange.
-4   ISO/IEC 2382-1:1993, Information technology -- Vocabulary -- Part 1: Fundamental
-    terms.
-5   ISO 4217, Codes for the representation of currencies and funds.
-6   ISO 8601, Data elements and interchange formats -- Information interchange --
-    Representation of dates and times.
-7   ISO/IEC 10646 (all parts), Information technology -- Universal Multiple-Octet Coded
-    Character Set (UCS).
-8   IEC 60559:1989, Binary floating-point arithmetic for microprocessor systems (previously
-    designated IEC 559:1989).
-
-
-
-
-[page 2] (Contents)
-
-
-    3. Terms, definitions, and symbols
-1   For the purposes of this International Standard, the following definitions apply. Other
-    terms are defined where they appear in italic type or on the left side of a syntax rule.
-    Terms explicitly defined in this International Standard are not to be presumed to refer
-    implicitly to similar terms defined elsewhere. Terms not defined in this International
-    Standard are to be interpreted according to ISO/IEC 2382-1. Mathematical symbols not
-    defined in this International Standard are to be interpreted according to ISO 31-11.
-    3.1
-1   access
-    <execution-time action> to read or modify the value of an object
-2   NOTE 1   Where only one of these two actions is meant, ''read'' or ''modify'' is used.
-
-3   NOTE 2   ''Modify'' includes the case where the new value being stored is the same as the previous value.
-
-4   NOTE 3   Expressions that are not evaluated do not access objects.
-
-    3.2
-1   alignment
-    requirement that objects of a particular type be located on storage boundaries with
-    addresses that are particular multiples of a byte address
-    3.3
-1   argument
-    actual argument
-    actual parameter (deprecated)
-    expression in the comma-separated list bounded by the parentheses in a function call
-    expression, or a sequence of preprocessing tokens in the comma-separated list bounded
-    by the parentheses in a function-like macro invocation
-    3.4
-1   behavior
-    external appearance or action
-    3.4.1
-1   implementation-defined behavior
-    unspecified behavior where each implementation documents how the choice is made
-2   EXAMPLE An example of implementation-defined behavior is the propagation of the high-order bit
-    when a signed integer is shifted right.
-
-    3.4.2
-1   locale-specific behavior
-    behavior that depends on local conventions of nationality, culture, and language that each
-    implementation documents
-
-
-[page 3] (Contents)
-
-2   EXAMPLE An example of locale-specific behavior is whether the islower function returns true for
-    characters other than the 26 lowercase Latin letters.
-
-    3.4.3
-1   undefined behavior
-    behavior, upon use of a nonportable or erroneous program construct or of erroneous data,
-    for which this International Standard imposes no requirements
-2   NOTE Possible undefined behavior ranges from ignoring the situation completely with unpredictable
-    results, to behaving during translation or program execution in a documented manner characteristic of the
-    environment (with or without the issuance of a diagnostic message), to terminating a translation or
-    execution (with the issuance of a diagnostic message).
-
-3   EXAMPLE        An example of undefined behavior is the behavior on integer overflow.
-
-    3.4.4
-1   unspecified behavior
-    use of an unspecified value, or other behavior where this International Standard provides
-    two or more possibilities and imposes no further requirements on which is chosen in any
-    instance
-2   EXAMPLE        An example of unspecified behavior is the order in which the arguments to a function are
-    evaluated.
-
-    3.5
-1   bit
-    unit of data storage in the execution environment large enough to hold an object that may
-    have one of two values
-2   NOTE     It need not be possible to express the address of each individual bit of an object.
-
-    3.6
-1   byte
-    addressable unit of data storage large enough to hold any member of the basic character
-    set of the execution environment
-2   NOTE 1     It is possible to express the address of each individual byte of an object uniquely.
-
-3   NOTE 2 A byte is composed of a contiguous sequence of bits, the number of which is implementation-
-    defined. The least significant bit is called the low-order bit; the most significant bit is called the high-order
-    bit.
-
-    3.7
-1   character
-    <abstract> member of a set of elements used for the organization, control, or
-    representation of data
-    3.7.1
-1   character
-    single-byte character
-    <C> bit representation that fits in a byte
-[page 4] (Contents)
-
-    3.7.2
-1   multibyte character
-    sequence of one or more bytes representing a member of the extended character set of
-    either the source or the execution environment
-2   NOTE    The extended character set is a superset of the basic character set.
-
-    3.7.3
-1   wide character
-    bit representation that fits in an object of type wchar_t, capable of representing any
-    character in the current locale
-    3.8
-1   constraint
-    restriction, either syntactic or semantic, by which the exposition of language elements is
-    to be interpreted
-    3.9
-1   correctly rounded result
-    representation in the result format that is nearest in value, subject to the current rounding
-    mode, to what the result would be given unlimited range and precision
-    3.10
-1   diagnostic message
-    message belonging to an implementation-defined subset of the implementation's message
-    output
-    3.11
-1   forward reference
-    reference to a later subclause of this International Standard that contains additional
-    information relevant to this subclause
-    3.12
-1   implementation
-    particular set of software, running in a particular translation environment under particular
-    control options, that performs translation of programs for, and supports execution of
-    functions in, a particular execution environment
-    3.13
-1   implementation limit
-    restriction imposed upon programs by the implementation
-    3.14
-1   memory location
-    either an object of scalar type, or a maximal sequence of adjacent bit-fields all having
-    nonzero width
-
-[page 5] (Contents)
-
-2   NOTE 1 Two threads of execution can update and access separate memory locations without interfering
-    with each other.
-
-3   NOTE 2 A bit-field and an adjacent non-bit-field member are in separate memory locations. The same
-    applies to two bit-fields, if one is declared inside a nested structure declaration and the other is not, or if the
-    two are separated by a zero-length bit-field declaration, or if they are separated by a non-bit-field member
-    declaration. It is not safe to concurrently update two non-atomic bit-fields in the same structure if all
-    members declared between them are also (non-zero-length) bit-fields, no matter what the sizes of those
-    intervening bit-fields happen to be.
-
-4   EXAMPLE        A structure declared as
-             struct {
-                   char a;
-                   int b:5, c:11, :0, d:8;
-                   struct { int ee:8; } e;
-             }
-    contains four separate memory locations: The member a, and bit-fields d and e.ee are each separate
-    memory locations, and can be modified concurrently without interfering with each other. The bit-fields b
-    and c together constitute the fourth memory location. The bit-fields b and c cannot be concurrently
-    modified, but b and a, for example, can be.
-
-    3.15
-1   object
-    region of data storage in the execution environment, the contents of which can represent
-    values
-2   NOTE      When referenced, an object may be interpreted as having a particular type; see 6.3.2.1.
-
-    3.16
-1   parameter
-    formal parameter
-    formal argument (deprecated)
-    object declared as part of a function declaration or definition that acquires a value on
-    entry to the function, or an identifier from the comma-separated list bounded by the
-    parentheses immediately following the macro name in a function-like macro definition
-    3.17
-1   recommended practice
-    specification that is strongly recommended as being in keeping with the intent of the
-    standard, but that may be impractical for some implementations
-    3.18
-1   runtime-constraint
-    requirement on a program when calling a library function
-2   NOTE 1 Despite the similar terms, a runtime-constraint is not a kind of constraint as defined by 3.8, and
-    need not be diagnosed at translation time.
-
-3   NOTE 2 Implementations that support the extensions in annex K are required to verify that the runtime-
-    constraints for a library function are not violated by the program; see K.3.1.4.
-
-[page 6] (Contents)
-
-    3.19
-1   value
-    precise meaning of the contents of an object when interpreted as having a specific type
-    3.19.1
-1   implementation-defined value
-    unspecified value where each implementation documents how the choice is made
-    3.19.2
-1   indeterminate value
-    either an unspecified value or a trap representation
-    3.19.3
-1   unspecified value
-    valid value of the relevant type where this International Standard imposes no
-    requirements on which value is chosen in any instance
-2   NOTE     An unspecified value cannot be a trap representation.
-
-    3.19.4
-1   trap representation
-    an object representation that need not represent a value of the object type
-    3.19.5
-1   perform a trap
-    interrupt execution of the program such that no further operations are performed
-2   NOTE In this International Standard, when the word ''trap'' is not immediately followed by
-    ''representation'', this is the intended usage.2)
-
-    3.20
-1   [^ x^]
-    ceiling of x: the least integer greater than or equal to x
-2   EXAMPLE       [^2.4^] is 3, [^-2.4^] is -2.
-
-    3.21
-1   [_ x_]
-    floor of x: the greatest integer less than or equal to x
-2   EXAMPLE       [_2.4_] is 2, [_-2.4_] is -3.
-
-
-
-
-    2)   For example, ''Trapping or stopping (if supported) is disabled...'' (F.8.2). Note that fetching a trap
-         representation might perform a trap but is not required to (see 6.2.6.1).
-
-[page 7] (Contents)
-
-
-    4. Conformance
-1   In this International Standard, ''shall'' is to be interpreted as a requirement on an
-    implementation or on a program; conversely, ''shall not'' is to be interpreted as a
-    prohibition.
-2   If a ''shall'' or ''shall not'' requirement that appears outside of a constraint or runtime-
-    constraint is violated, the behavior is undefined. Undefined behavior is otherwise
-    indicated in this International Standard by the words ''undefined behavior'' or by the
-    omission of any explicit definition of behavior. There is no difference in emphasis among
-    these three; they all describe ''behavior that is undefined''.
-3   A program that is correct in all other aspects, operating on correct data, containing
-    unspecified behavior shall be a correct program and act in accordance with 5.1.2.3.
-4   The implementation shall not successfully translate a preprocessing translation unit
-    containing a #error preprocessing directive unless it is part of a group skipped by
-    conditional inclusion.
-5   A strictly conforming program shall use only those features of the language and library
-    specified in this International Standard.3) It shall not produce output dependent on any
-    unspecified, undefined, or implementation-defined behavior, and shall not exceed any
-    minimum implementation limit.
-6   The two forms of conforming implementation are hosted and freestanding. A conforming
-    hosted implementation shall accept any strictly conforming program. A conforming
-    freestanding implementation shall accept any strictly conforming program that does not
-    use complex types and in which the use of the features specified in the library clause
-    (clause 7) is confined to the contents of the standard headers <float.h>,
-    <iso646.h>, <limits.h>, <stdalign.h>, <stdarg.h>, <stdbool.h>,
-    <stddef.h>, and <stdint.h>. A conforming implementation may have extensions
-    (including additional library functions), provided they do not alter the behavior of any
-    strictly conforming program.4)
-
-
-
-    3)   A strictly conforming program can use conditional features (see 6.10.8.3) provided the use is guarded
-         by an appropriate conditional inclusion preprocessing directive using the related macro. For example:
-                 #ifdef __STDC_IEC_559__ /* FE_UPWARD defined */
-                    /* ... */
-                    fesetround(FE_UPWARD);
-                    /* ... */
-                 #endif
-
-    4)   This implies that a conforming implementation reserves no identifiers other than those explicitly
-         reserved in this International Standard.
-
-[page 8] (Contents)
-
-7   A conforming program is one that is acceptable to a conforming implementation.5)
-8   An implementation shall be accompanied by a document that defines all implementation-
-    defined and locale-specific characteristics and all extensions.
-    Forward references: conditional inclusion (6.10.1), error directive (6.10.5),
-    characteristics of floating types <float.h> (7.7), alternative spellings <iso646.h>
-    (7.9), sizes of integer types <limits.h> (7.10), alignment <stdalign.h> (7.15),
-    variable arguments <stdarg.h> (7.16), boolean type and values <stdbool.h>
-    (7.18), common definitions <stddef.h> (7.19), integer types <stdint.h> (7.20).
-
-
-
-
-    5)   Strictly conforming programs are intended to be maximally portable among conforming
-         implementations. Conforming programs may depend upon nonportable features of a conforming
-         implementation.
-
-[page 9] (Contents)
-
-
-    5. Environment
-1   An implementation translates C source files and executes C programs in two data-
-    processing-system environments, which will be called the translation environment and
-    the execution environment in this International Standard. Their characteristics define and
-    constrain the results of executing conforming C programs constructed according to the
-    syntactic and semantic rules for conforming implementations.
-    Forward references: In this clause, only a few of many possible forward references
-    have been noted.
-    5.1 Conceptual models
-    5.1.1 Translation environment
-    5.1.1.1 Program structure
-1   A C program need not all be translated at the same time. The text of the program is kept
-    in units called source files, (or preprocessing files) in this International Standard. A
-    source file together with all the headers and source files included via the preprocessing
-    directive #include is known as a preprocessing translation unit. After preprocessing, a
-    preprocessing translation unit is called a translation unit. Previously translated translation
-    units may be preserved individually or in libraries. The separate translation units of a
-    program communicate by (for example) calls to functions whose identifiers have external
-    linkage, manipulation of objects whose identifiers have external linkage, or manipulation
-    of data files. Translation units may be separately translated and then later linked to
-    produce an executable program.
-    Forward references: linkages of identifiers (6.2.2), external definitions (6.9),
-    preprocessing directives (6.10).
-    5.1.1.2 Translation phases
-1   The precedence among the syntax rules of translation is specified by the following
-    phases.6)
-         1.   Physical source file multibyte characters are mapped, in an implementation-
-              defined manner, to the source character set (introducing new-line characters for
-              end-of-line indicators) if necessary. Trigraph sequences are replaced by
-              corresponding single-character internal representations.
-
-
-
-    6)    Implementations shall behave as if these separate phases occur, even though many are typically folded
-          together in practice. Source files, translation units, and translated translation units need not
-          necessarily be stored as files, nor need there be any one-to-one correspondence between these entities
-          and any external representation. The description is conceptual only, and does not specify any
-          particular implementation.
-
-[page 10] (Contents)
-
-     2.   Each instance of a backslash character (\) immediately followed by a new-line
-          character is deleted, splicing physical source lines to form logical source lines.
-          Only the last backslash on any physical source line shall be eligible for being part
-          of such a splice. A source file that is not empty shall end in a new-line character,
-          which shall not be immediately preceded by a backslash character before any such
-          splicing takes place.
-     3.   The source file is decomposed into preprocessing tokens7) and sequences of
-          white-space characters (including comments). A source file shall not end in a
-          partial preprocessing token or in a partial comment. Each comment is replaced by
-          one space character. New-line characters are retained. Whether each nonempty
-          sequence of white-space characters other than new-line is retained or replaced by
-          one space character is implementation-defined.
-     4. Preprocessing directives are executed, macro invocations are expanded, and
-        _Pragma unary operator expressions are executed. If a character sequence that
-        matches the syntax of a universal character name is produced by token
-        concatenation (6.10.3.3), the behavior is undefined. A #include preprocessing
-        directive causes the named header or source file to be processed from phase 1
-        through phase 4, recursively. All preprocessing directives are then deleted.
-     5. Each source character set member and escape sequence in character constants and
-        string literals is converted to the corresponding member of the execution character
-        set; if there is no corresponding member, it is converted to an implementation-
-        defined member other than the null (wide) character.8)
-     6.   Adjacent string literal tokens are concatenated.
-     7. White-space characters separating tokens are no longer significant. Each
-        preprocessing token is converted into a token. The resulting tokens are
-        syntactically and semantically analyzed and translated as a translation unit.
-     8.   All external object and function references are resolved. Library components are
-          linked to satisfy external references to functions and objects not defined in the
-          current translation. All such translator output is collected into a program image
-          which contains information needed for execution in its execution environment.
-Forward references: universal character names (6.4.3), lexical elements (6.4),
-preprocessing directives (6.10), trigraph sequences (5.2.1.1), external definitions (6.9).
-
-
-
-7)    As described in 6.4, the process of dividing a source file's characters into preprocessing tokens is
-      context-dependent. For example, see the handling of < within a #include preprocessing directive.
-8)    An implementation need not convert all non-corresponding source characters to the same execution
-      character.
-
-[page 11] (Contents)
-
-    5.1.1.3 Diagnostics
-1   A conforming implementation shall produce at least one diagnostic message (identified in
-    an implementation-defined manner) if a preprocessing translation unit or translation unit
-    contains a violation of any syntax rule or constraint, even if the behavior is also explicitly
-    specified as undefined or implementation-defined. Diagnostic messages need not be
-    produced in other circumstances.9)
-2   EXAMPLE        An implementation shall issue a diagnostic for the translation unit:
-             char i;
-             int i;
-    because in those cases where wording in this International Standard describes the behavior for a construct
-    as being both a constraint error and resulting in undefined behavior, the constraint error shall be diagnosed.
-
-    5.1.2 Execution environments
-1   Two execution environments are defined: freestanding and hosted. In both cases,
-    program startup occurs when a designated C function is called by the execution
-    environment. All objects with static storage duration shall be initialized (set to their
-    initial values) before program startup. The manner and timing of such initialization are
-    otherwise unspecified. Program termination returns control to the execution
-    environment.
-    Forward references: storage durations of objects (6.2.4), initialization (6.7.9).
-    5.1.2.1 Freestanding environment
-1   In a freestanding environment (in which C program execution may take place without any
-    benefit of an operating system), the name and type of the function called at program
-    startup are implementation-defined. Any library facilities available to a freestanding
-    program, other than the minimal set required by clause 4, are implementation-defined.
-2   The effect of program termination in a freestanding environment is implementation-
-    defined.
-    5.1.2.2 Hosted environment
-1   A hosted environment need not be provided, but shall conform to the following
-    specifications if present.
-
-
-
-
-    9)   The intent is that an implementation should identify the nature of, and where possible localize, each
-         violation. Of course, an implementation is free to produce any number of diagnostics as long as a
-         valid program is still correctly translated. It may also successfully translate an invalid program.
-
-[page 12] (Contents)
-
-    5.1.2.2.1 Program startup
-1   The function called at program startup is named main. The implementation declares no
-    prototype for this function. It shall be defined with a return type of int and with no
-    parameters:
-            int main(void) { /* ... */ }
-    or with two parameters (referred to here as argc and argv, though any names may be
-    used, as they are local to the function in which they are declared):
-            int main(int argc, char *argv[]) { /* ... */ }
-    or equivalent;10) or in some other implementation-defined manner.
-2   If they are declared, the parameters to the main function shall obey the following
-    constraints:
-    -- The value of argc shall be nonnegative.
-    -- argv[argc] shall be a null pointer.
-    -- If the value of argc is greater than zero, the array members argv[0] through
-      argv[argc-1] inclusive shall contain pointers to strings, which are given
-      implementation-defined values by the host environment prior to program startup. The
-      intent is to supply to the program information determined prior to program startup
-      from elsewhere in the hosted environment. If the host environment is not capable of
-      supplying strings with letters in both uppercase and lowercase, the implementation
-      shall ensure that the strings are received in lowercase.
-    -- If the value of argc is greater than zero, the string pointed to by argv[0]
-      represents the program name; argv[0][0] shall be the null character if the
-      program name is not available from the host environment. If the value of argc is
-      greater than one, the strings pointed to by argv[1] through argv[argc-1]
-      represent the program parameters.
-    -- The parameters argc and argv and the strings pointed to by the argv array shall
-      be modifiable by the program, and retain their last-stored values between program
-      startup and program termination.
-    5.1.2.2.2 Program execution
-1   In a hosted environment, a program may use all the functions, macros, type definitions,
-    and objects described in the library clause (clause 7).
-
-
-
-
-    10) Thus, int can be replaced by a typedef name defined as int, or the type of argv can be written as
-        char ** argv, and so on.
-
-[page 13] (Contents)
-
-    5.1.2.2.3 Program termination
-1   If the return type of the main function is a type compatible with int, a return from the
-    initial call to the main function is equivalent to calling the exit function with the value
-    returned by the main function as its argument;11) reaching the } that terminates the
-    main function returns a value of 0. If the return type is not compatible with int, the
-    termination status returned to the host environment is unspecified.
-    Forward references: definition of terms (7.1.1), the exit function (7.22.4.4).
-    5.1.2.3 Program execution
-1   The semantic descriptions in this International Standard describe the behavior of an
-    abstract machine in which issues of optimization are irrelevant.
-2   Accessing a volatile object, modifying an object, modifying a file, or calling a function
-    that does any of those operations are all side effects,12) which are changes in the state of
-    the execution environment. Evaluation of an expression in general includes both value
-    computations and initiation of side effects. Value computation for an lvalue expression
-    includes determining the identity of the designated object.
-3   Sequenced before is an asymmetric, transitive, pair-wise relation between evaluations
-    executed by a single thread, which induces a partial order among those evaluations.
-    Given any two evaluations A and B, if A is sequenced before B, then the execution of A
-    shall precede the execution of B. (Conversely, if A is sequenced before B, then B is
-    sequenced after A.) If A is not sequenced before or after B, then A and B are
-    unsequenced. Evaluations A and B are indeterminately sequenced when A is sequenced
-    either before or after B, but it is unspecified which.13) The presence of a sequence point
-    between the evaluation of expressions A and B implies that every value computation and
-    side effect associated with A is sequenced before every value computation and side effect
-    associated with B. (A summary of the sequence points is given in annex C.)
-4   In the abstract machine, all expressions are evaluated as specified by the semantics. An
-    actual implementation need not evaluate part of an expression if it can deduce that its
-    value is not used and that no needed side effects are produced (including any caused by
-
-    11) In accordance with 6.2.4, the lifetimes of objects with automatic storage duration declared in main
-        will have ended in the former case, even where they would not have in the latter.
-    12) The IEC 60559 standard for binary floating-point arithmetic requires certain user-accessible status
-        flags and control modes. Floating-point operations implicitly set the status flags; modes affect result
-        values of floating-point operations. Implementations that support such floating-point state are
-        required to regard changes to it as side effects -- see annex F for details. The floating-point
-        environment library <fenv.h> provides a programming facility for indicating when these side
-        effects matter, freeing the implementations in other cases.
-    13) The executions of unsequenced evaluations can interleave. Indeterminately sequenced evaluations
-        cannot interleave, but can be executed in any order.
-
-[page 14] (Contents)
-
-     calling a function or accessing a volatile object).
-5    When the processing of the abstract machine is interrupted by receipt of a signal, the
-     values of objects that are neither lock-free atomic objects nor of type volatile
-     sig_atomic_t are unspecified, and the value of any object that is modified by the
-     handler that is neither a lock-free atomic object nor of type volatile
-     sig_atomic_t becomes undefined.
-6    The least requirements on a conforming implementation are:
-     -- Accesses to volatile objects are evaluated strictly according to the rules of the abstract
-       machine.
-     -- At program termination, all data written into files shall be identical to the result that
-       execution of the program according to the abstract semantics would have produced.
-     -- The input and output dynamics of interactive devices shall take place as specified in
-       7.21.3. The intent of these requirements is that unbuffered or line-buffered output
-       appear as soon as possible, to ensure that prompting messages actually appear prior to
-       a program waiting for input.
-     This is the observable behavior of the program.
-7    What constitutes an interactive device is implementation-defined.
-8    More stringent correspondences between abstract and actual semantics may be defined by
-     each implementation.
-9    EXAMPLE 1 An implementation might define a one-to-one correspondence between abstract and actual
-     semantics: at every sequence point, the values of the actual objects would agree with those specified by the
-     abstract semantics. The keyword volatile would then be redundant.
-10   Alternatively, an implementation might perform various optimizations within each translation unit, such
-     that the actual semantics would agree with the abstract semantics only when making function calls across
-     translation unit boundaries. In such an implementation, at the time of each function entry and function
-     return where the calling function and the called function are in different translation units, the values of all
-     externally linked objects and of all objects accessible via pointers therein would agree with the abstract
-     semantics. Furthermore, at the time of each such function entry the values of the parameters of the called
-     function and of all objects accessible via pointers therein would agree with the abstract semantics. In this
-     type of implementation, objects referred to by interrupt service routines activated by the signal function
-     would require explicit specification of volatile storage, as well as other implementation-defined
-     restrictions.
-
-11   EXAMPLE 2       In executing the fragment
-              char c1, c2;
-              /* ... */
-              c1 = c1 + c2;
-     the ''integer promotions'' require that the abstract machine promote the value of each variable to int size
-     and then add the two ints and truncate the sum. Provided the addition of two chars can be done without
-     overflow, or with overflow wrapping silently to produce the correct result, the actual execution need only
-     produce the same result, possibly omitting the promotions.
-
-[page 15] (Contents)
-
-12   EXAMPLE 3       Similarly, in the fragment
-              float f1, f2;
-              double d;
-              /* ... */
-              f1 = f2 * d;
-     the multiplication may be executed using single-precision arithmetic if the implementation can ascertain
-     that the result would be the same as if it were executed using double-precision arithmetic (for example, if d
-     were replaced by the constant 2.0, which has type double).
-
-13   EXAMPLE 4 Implementations employing wide registers have to take care to honor appropriate
-     semantics. Values are independent of whether they are represented in a register or in memory. For
-     example, an implicit spilling of a register is not permitted to alter the value. Also, an explicit store and load
-     is required to round to the precision of the storage type. In particular, casts and assignments are required to
-     perform their specified conversion. For the fragment
-              double d1, d2;
-              float f;
-              d1 = f = expression;
-              d2 = (float) expression;
-     the values assigned to d1 and d2 are required to have been converted to float.
-
-14   EXAMPLE 5 Rearrangement for floating-point expressions is often restricted because of limitations in
-     precision as well as range. The implementation cannot generally apply the mathematical associative rules
-     for addition or multiplication, nor the distributive rule, because of roundoff error, even in the absence of
-     overflow and underflow. Likewise, implementations cannot generally replace decimal constants in order to
-     rearrange expressions. In the following fragment, rearrangements suggested by mathematical rules for real
-     numbers are often not valid (see F.9).
-              double x, y, z;
-              /* ... */
-              x = (x * y) * z;            //   not equivalent to x   *= y * z;
-              z = (x - y) + y ;           //   not equivalent to z   = x;
-              z = x + x * y;              //   not equivalent to z   = x * (1.0 + y);
-              y = x / 5.0;                //   not equivalent to y   = x * 0.2;
-
-15   EXAMPLE 6       To illustrate the grouping behavior of expressions, in the following fragment
-              int a, b;
-              /* ... */
-              a = a + 32760 + b + 5;
-     the expression statement behaves exactly the same as
-              a = (((a + 32760) + b) + 5);
-     due to the associativity and precedence of these operators. Thus, the result of the sum (a + 32760) is
-     next added to b, and that result is then added to 5 which results in the value assigned to a. On a machine in
-     which overflows produce an explicit trap and in which the range of values representable by an int is
-     [-32768, +32767], the implementation cannot rewrite this expression as
-              a = ((a + b) + 32765);
-     since if the values for a and b were, respectively, -32754 and -15, the sum a + b would produce a trap
-     while the original expression would not; nor can the expression be rewritten either as
-
-
-[page 16] (Contents)
-
-              a = ((a + 32765) + b);
-     or
-              a = (a + (b + 32765));
-     since the values for a and b might have been, respectively, 4 and -8 or -17 and 12. However, on a machine
-     in which overflow silently generates some value and where positive and negative overflows cancel, the
-     above expression statement can be rewritten by the implementation in any of the above ways because the
-     same result will occur.
-
-16   EXAMPLE 7 The grouping of an expression does not completely determine its evaluation. In the
-     following fragment
-              #include <stdio.h>
-              int sum;
-              char *p;
-              /* ... */
-              sum = sum * 10 - '0' + (*p++ = getchar());
-     the expression statement is grouped as if it were written as
-              sum = (((sum * 10) - '0') + ((*(p++)) = (getchar())));
-     but the actual increment of p can occur at any time between the previous sequence point and the next
-     sequence point (the ;), and the call to getchar can occur at any point prior to the need of its returned
-     value.
-
-     Forward references: expressions (6.5), type qualifiers (6.7.3), statements (6.8), the
-     signal function (7.14), files (7.21.3).
-     5.1.2.4 Multi-threaded executions and data races
-1    Under a hosted implementation, a program can have more than one thread of execution
-     (or thread) running concurrently. The execution of each thread proceeds as defined by
-     the remainder of this standard. The execution of the entire program consists of an
-     execution of all of its threads.14) Under a freestanding implementation, it is
-     implementation-defined whether a program can have more than one thread of execution.
-2    The value of an object visible to a thread T at a particular point is the initial value of the
-     object, a value stored in the object by T , or a value stored in the object by another thread,
-     according to the rules below.
-3    NOTE 1 In some cases, there may instead be undefined behavior. Much of this section is motivated by
-     the desire to support atomic operations with explicit and detailed visibility constraints. However, it also
-     implicitly supports a simpler view for more restricted programs.
-
-4    Two expression evaluations conflict if one of them modifies a memory location and the
-     other one accesses or modifies the same memory location.
-
-
-
-
-     14) The execution can usually be viewed as an interleaving of all of the threads. However, some kinds of
-         atomic operations, for example, allow executions inconsistent with a simple interleaving as described
-         below.
-
-[page 17] (Contents)
-
-5    The library defines a number of atomic operations (7.17) and operations on mutexes
-     (7.25.4) that are specially identified as synchronization operations. These operations play
-     a special role in making assignments in one thread visible to another. A synchronization
-     operation on one or more memory locations is either an acquire operation, a release
-     operation, both an acquire and release operation, or a consume operation. A
-     synchronization operation without an associated memory location is a fence and can be
-     either an acquire fence, a release fence, or both an acquire and release fence. In addition,
-     there are relaxed atomic operations, which are not synchronization operations, and
-     atomic read-modify-write operations, which have special characteristics.
-6    NOTE 2 For example, a call that acquires a mutex will perform an acquire operation on the locations
-     composing the mutex. Correspondingly, a call that releases the same mutex will perform a release
-     operation on those same locations. Informally, performing a release operation on A forces prior side effects
-     on other memory locations to become visible to other threads that later perform an acquire or consume
-     operation on A. We do not include relaxed atomic operations as synchronization operations although, like
-     synchronization operations, they cannot contribute to data races.
-
-7    All modifications to a particular atomic object M occur in some particular total order,
-     called the modification order of M. If A and B are modifications of an atomic object M,
-     and A happens before B, then A shall precede B in the modification order of M, which is
-     defined below.
-8    NOTE 3     This states that the modification orders must respect the ''happens before'' relation.
-
-9    NOTE 4 There is a separate order for each atomic object. There is no requirement that these can be
-     combined into a single total order for all objects. In general this will be impossible since different threads
-     may observe modifications to different variables in inconsistent orders.
-
-10   A release sequence on an atomic object M is a maximal contiguous sub-sequence of side
-     effects in the modification order of M, where the first operation is a release and every
-     subsequent operation either is performed by the same thread that performed the release or
-     is an atomic read-modify-write operation.
-11   Certain library calls synchronize with other library calls performed by another thread. In
-     particular, an atomic operation A that performs a release operation on an object M
-     synchronizes with an atomic operation B that performs an acquire operation on M and
-     reads a value written by any side effect in the release sequence headed by A.
-12   NOTE 5 Except in the specified cases, reading a later value does not necessarily ensure visibility as
-     described below. Such a requirement would sometimes interfere with efficient implementation.
-
-13   NOTE 6 The specifications of the synchronization operations define when one reads the value written by
-     another. For atomic variables, the definition is clear. All operations on a given mutex occur in a single total
-     order. Each mutex acquisition ''reads the value written'' by the last mutex release.
-
-14   An evaluation A carries a dependency 15) to an evaluation B if:
-
-
-     15) The ''carries a dependency'' relation is a subset of the ''sequenced before'' relation, and is similarly
-         strictly intra-thread.
-
-[page 18] (Contents)
-
-     -- the value of A is used as an operand of B, unless:
-           o B is an invocation of the kill_dependency macro,
-
-           o A is the left operand of a && or || operator,
-
-           o A is the left operand of a ? : operator, or
-
-           o A is the left operand of a , operator;
-         or
-     -- A writes a scalar object or bit-field M, B reads from M the value written by A, and A
-       is sequenced before B, or
-     -- for some evaluation X, A carries a dependency to X and X carries a dependency to B.
-15   An evaluation A is dependency-ordered before16) an evaluation B if:
-     -- A performs a release operation on an atomic object M, and B performs a consume
-       operation on M and reads a value written by any side effect in the release sequence
-       headed by A, or
-     -- for some evaluation X, A is dependency-ordered before X and X carries a
-       dependency to B.
-16   An evaluation A inter-thread happens before an evaluation B if A synchronizes with B, A
-     is dependency-ordered before B, or, for some evaluation X:
-     -- A synchronizes with X and X is sequenced before B,
-     -- A is sequenced before X and X inter-thread happens before B, or
-     -- A inter-thread happens before X and X inter-thread happens before B.
-17   NOTE 7 The ''inter-thread happens before'' relation describes arbitrary concatenations of ''sequenced
-     before'', ''synchronizes with'', and ''dependency-ordered before'' relationships, with two exceptions. The
-     first exception is that a concatenation is not permitted to end with ''dependency-ordered before'' followed
-     by ''sequenced before''. The reason for this limitation is that a consume operation participating in a
-     ''dependency-ordered before'' relationship provides ordering only with respect to operations to which this
-     consume operation actually carries a dependency. The reason that this limitation applies only to the end of
-     such a concatenation is that any subsequent release operation will provide the required ordering for a prior
-     consume operation. The second exception is that a concatenation is not permitted to consist entirely of
-     ''sequenced before''. The reasons for this limitation are (1) to permit ''inter-thread happens before'' to be
-     transitively closed and (2) the ''happens before'' relation, defined below, provides for relationships
-     consisting entirely of ''sequenced before''.
-
-18   An evaluation A happens before an evaluation B if A is sequenced before B or A inter-
-     thread happens before B.
-
-
-
-     16) The ''dependency-ordered before'' relation is analogous to the ''synchronizes with'' relation, but uses
-         release/consume in place of release/acquire.
-
-[page 19] (Contents)
-
-19   A visible side effect A on an object M with respect to a value computation B of M
-     satisfies the conditions:
-     -- A happens before B, and
-     -- there is no other side effect X to M such that A happens before X and X happens
-         before B.
-     The value of a non-atomic scalar object M, as determined by evaluation B, shall be the
-     value stored by the visible side effect A.
-20   NOTE 8 If there is ambiguity about which side effect to a non-atomic object is visible, then there is a data
-     race and the behavior is undefined.
-
-21   NOTE 9 This states that operations on ordinary variables are not visibly reordered. This is not actually
-     detectable without data races, but it is necessary to ensure that data races, as defined here, and with suitable
-     restrictions on the use of atomics, correspond to data races in a simple interleaved (sequentially consistent)
-     execution.
-
-22   The visible sequence of side effects on an atomic object M, with respect to a value
-     computation B of M, is a maximal contiguous sub-sequence of side effects in the
-     modification order of M, where the first side effect is visible with respect to B, and for
-     every subsequent side effect, it is not the case that B happens before it. The value of an
-     atomic object M, as determined by evaluation B, shall be the value stored by some
-     operation in the visible sequence of M with respect to B. Furthermore, if a value
-     computation A of an atomic object M happens before a value computation B of M, and
-     the value computed by A corresponds to the value stored by side effect X, then the value
-     computed by B shall either equal the value computed by A, or be the value stored by side
-     effect Y , where Y follows X in the modification order of M.
-23   NOTE 10 This effectively disallows compiler reordering of atomic operations to a single object, even if
-     both operations are ''relaxed'' loads. By doing so, we effectively make the ''cache coherence'' guarantee
-     provided by most hardware available to C atomic operations.
-
-24   NOTE 11 The visible sequence depends on the ''happens before'' relation, which in turn depends on the
-     values observed by loads of atomics, which we are restricting here. The intended reading is that there must
-     exist an association of atomic loads with modifications they observe that, together with suitably chosen
-     modification orders and the ''happens before'' relation derived as described above, satisfy the resulting
-     constraints as imposed here.
-
-25   The execution of a program contains a data race if it contains two conflicting actions in
-     different threads, at least one of which is not atomic, and neither happens before the
-     other. Any such data race results in undefined behavior.
-26   NOTE 12 It can be shown that programs that correctly use simple mutexes and
-     memory_order_seq_cst operations to prevent all data races, and use no other synchronization
-     operations, behave as though the operations executed by their constituent threads were simply interleaved,
-     with each value computation of an object being the last value stored in that interleaving. This is normally
-     referred to as ''sequential consistency''. However, this applies only to data-race-free programs, and data-
-     race-free programs cannot observe most program transformations that do not change single-threaded
-     program semantics. In fact, most single-threaded program transformations continue to be allowed, since
-     any program that behaves differently as a result must contain undefined behavior.
-
-[page 20] (Contents)
-
-27   NOTE 13 Compiler transformations that introduce assignments to a potentially shared memory location
-     that would not be modified by the abstract machine are generally precluded by this standard, since such an
-     assignment might overwrite another assignment by a different thread in cases in which an abstract machine
-     execution would not have encountered a data race. This includes implementations of data member
-     assignment that overwrite adjacent members in separate memory locations. We also generally preclude
-     reordering of atomic loads in cases in which the atomics in question may alias, since this may violate the
-     "visible sequence" rules.
-
-28   NOTE 14 Transformations that introduce a speculative read of a potentially shared memory location may
-     not preserve the semantics of the program as defined in this standard, since they potentially introduce a data
-     race. However, they are typically valid in the context of an optimizing compiler that targets a specific
-     machine with well-defined semantics for data races. They would be invalid for a hypothetical machine that
-     is not tolerant of races or provides hardware race detection.
-
-
-
-
-[page 21] (Contents)
-
-    5.2 Environmental considerations
-    5.2.1 Character sets
-1   Two sets of characters and their associated collating sequences shall be defined: the set in
-    which source files are written (the source character set), and the set interpreted in the
-    execution environment (the execution character set). Each set is further divided into a
-    basic character set, whose contents are given by this subclause, and a set of zero or more
-    locale-specific members (which are not members of the basic character set) called
-    extended characters. The combined set is also called the extended character set. The
-    values of the members of the execution character set are implementation-defined.
-2   In a character constant or string literal, members of the execution character set shall be
-    represented by corresponding members of the source character set or by escape
-    sequences consisting of the backslash \ followed by one or more characters. A byte with
-    all bits set to 0, called the null character, shall exist in the basic execution character set; it
-    is used to terminate a character string.
-3   Both the basic source and basic execution character sets shall have the following
-    members: the 26 uppercase letters of the Latin alphabet
-            A    B   C      D   E   F    G    H    I    J    K    L   M
-            N    O   P      Q   R   S    T    U    V    W    X    Y   Z
-    the 26 lowercase letters of the Latin alphabet
-            a    b   c      d   e   f    g    h    i    j    k    l   m
-            n    o   p      q   r   s    t    u    v    w    x    y   z
-    the 10 decimal digits
-            0    1   2      3   4   5    6    7    8    9
-    the following 29 graphic characters
-            !    "   #      %   &   '    (    )    *    +    ,    -   .    /    :
-            ;    <   =      >   ?   [    \    ]    ^    _    {    |   }    ~
-    the space character, and control characters representing horizontal tab, vertical tab, and
-    form feed. The representation of each member of the source and execution basic
-    character sets shall fit in a byte. In both the source and execution basic character sets, the
-    value of each character after 0 in the above list of decimal digits shall be one greater than
-    the value of the previous. In source files, there shall be some way of indicating the end of
-    each line of text; this International Standard treats such an end-of-line indicator as if it
-    were a single new-line character. In the basic execution character set, there shall be
-    control characters representing alert, backspace, carriage return, and new line. If any
-    other characters are encountered in a source file (except in an identifier, a character
-    constant, a string literal, a header name, a comment, or a preprocessing token that is never
-
-[page 22] (Contents)
-
-    converted to a token), the behavior is undefined.
-4   A letter is an uppercase letter or a lowercase letter as defined above; in this International
-    Standard the term does not include other characters that are letters in other alphabets.
-5   The universal character name construct provides a way to name other characters.
-    Forward references: universal character names (6.4.3), character constants (6.4.4.4),
-    preprocessing directives (6.10), string literals (6.4.5), comments (6.4.9), string (7.1.1).
-    5.2.1.1 Trigraph sequences
-1   Before any other processing takes place, each occurrence of one of the following
-    sequences of three characters (called trigraph sequences17)) is replaced with the
-    corresponding single character.
-           ??=      #                       ??)      ]                       ??!     |
-           ??(      [                       ??'      ^                       ??>     }
-           ??/      \                       ??<      {                       ??-     ~
-    No other trigraph sequences exist. Each ? that does not begin one of the trigraphs listed
-    above is not changed.
-2   EXAMPLE 1
-              ??=define arraycheck(a, b) a??(b??) ??!??! b??(a??)
-    becomes
-              #define arraycheck(a, b) a[b] || b[a]
-
-3   EXAMPLE 2      The following source line
-              printf("Eh???/n");
-    becomes (after replacement of the trigraph sequence ??/)
-              printf("Eh?\n");
-
-    5.2.1.2 Multibyte characters
-1   The source character set may contain multibyte characters, used to represent members of
-    the extended character set. The execution character set may also contain multibyte
-    characters, which need not have the same encoding as for the source character set. For
-    both character sets, the following shall hold:
-    -- The basic character set shall be present and each character shall be encoded as a
-      single byte.
-    -- The presence, meaning, and representation of any additional members is locale-
-      specific.
-
-    17) The trigraph sequences enable the input of characters that are not defined in the Invariant Code Set as
-        described in ISO/IEC 646, which is a subset of the seven-bit US ASCII code set.
-
-[page 23] (Contents)
-
-    -- A multibyte character set may have a state-dependent encoding, wherein each
-      sequence of multibyte characters begins in an initial shift state and enters other
-      locale-specific shift states when specific multibyte characters are encountered in the
-      sequence. While in the initial shift state, all single-byte characters retain their usual
-      interpretation and do not alter the shift state. The interpretation for subsequent bytes
-      in the sequence is a function of the current shift state.
-    -- A byte with all bits zero shall be interpreted as a null character independent of shift
-      state. Such a byte shall not occur as part of any other multibyte character.
-2   For source files, the following shall hold:
-    -- An identifier, comment, string literal, character constant, or header name shall begin
-      and end in the initial shift state.
-    -- An identifier, comment, string literal, character constant, or header name shall consist
-      of a sequence of valid multibyte characters.
-    5.2.2 Character display semantics
-1   The active position is that location on a display device where the next character output by
-    the fputc function would appear. The intent of writing a printing character (as defined
-    by the isprint function) to a display device is to display a graphic representation of
-    that character at the active position and then advance the active position to the next
-    position on the current line. The direction of writing is locale-specific. If the active
-    position is at the final position of a line (if there is one), the behavior of the display device
-    is unspecified.
-2   Alphabetic escape sequences representing nongraphic characters in the execution
-    character set are intended to produce actions on display devices as follows:
-    \a (alert) Produces an audible or visible alert without changing the active position.
-    \b (backspace) Moves the active position to the previous position on the current line. If
-       the active position is at the initial position of a line, the behavior of the display
-       device is unspecified.
-    \f ( form feed) Moves the active position to the initial position at the start of the next
-       logical page.
-    \n (new line) Moves the active position to the initial position of the next line.
-    \r (carriage return) Moves the active position to the initial position of the current line.
-    \t (horizontal tab) Moves the active position to the next horizontal tabulation position
-       on the current line. If the active position is at or past the last defined horizontal
-       tabulation position, the behavior of the display device is unspecified.
-    \v (vertical tab) Moves the active position to the initial position of the next vertical
-       tabulation position. If the active position is at or past the last defined vertical
-[page 24] (Contents)
-
-         tabulation position, the behavior of the display device is unspecified.
-3   Each of these escape sequences shall produce a unique implementation-defined value
-    which can be stored in a single char object. The external representations in a text file
-    need not be identical to the internal representations, and are outside the scope of this
-    International Standard.
-    Forward references: the isprint function (7.4.1.8), the fputc function (7.21.7.3).
-    5.2.3 Signals and interrupts
-1   Functions shall be implemented such that they may be interrupted at any time by a signal,
-    or may be called by a signal handler, or both, with no alteration to earlier, but still active,
-    invocations' control flow (after the interruption), function return values, or objects with
-    automatic storage duration. All such objects shall be maintained outside the function
-    image (the instructions that compose the executable representation of a function) on a
-    per-invocation basis.
-    5.2.4 Environmental limits
-1   Both the translation and execution environments constrain the implementation of
-    language translators and libraries. The following summarizes the language-related
-    environmental limits on a conforming implementation; the library-related limits are
-    discussed in clause 7.
-    5.2.4.1 Translation limits
-1   The implementation shall be able to translate and execute at least one program that
-    contains at least one instance of every one of the following limits:18)
-    -- 127 nesting levels of blocks
-    -- 63 nesting levels of conditional inclusion
-    -- 12 pointer, array, and function declarators (in any combinations) modifying an
-      arithmetic, structure, union, or void type in a declaration
-    -- 63 nesting levels of parenthesized declarators within a full declarator
-    -- 63 nesting levels of parenthesized expressions within a full expression
-    -- 63 significant initial characters in an internal identifier or a macro name (each
-      universal character name or extended source character is considered a single
-      character)
-    -- 31 significant initial characters in an external identifier (each universal character name
-      specifying a short identifier of 0000FFFF or less is considered 6 characters, each
-
-
-    18) Implementations should avoid imposing fixed translation limits whenever possible.
-
-[page 25] (Contents)
-
-         universal character name specifying a short identifier of 00010000 or more is
-         considered 10 characters, and each extended source character is considered the same
-         number of characters as the corresponding universal character name, if any)19)
-    -- 4095 external identifiers in one translation unit
-    -- 511 identifiers with block scope declared in one block
-    -- 4095 macro identifiers simultaneously defined in one preprocessing translation unit
-    -- 127 parameters in one function definition
-    -- 127 arguments in one function call
-    -- 127 parameters in one macro definition
-    -- 127 arguments in one macro invocation
-    -- 4095 characters in a logical source line
-    -- 4095 characters in a string literal (after concatenation)
-    -- 65535 bytes in an object (in a hosted environment only)
-    -- 15 nesting levels for #included files
-    -- 1023 case labels for a switch statement (excluding those for any nested switch
-      statements)
-    -- 1023 members in a single structure or union
-    -- 1023 enumeration constants in a single enumeration
-    -- 63 levels of nested structure or union definitions in a single struct-declaration-list
-    5.2.4.2 Numerical limits
-1   An implementation is required to document all the limits specified in this subclause,
-    which are specified in the headers <limits.h> and <float.h>. Additional limits are
-    specified in <stdint.h>.
-    Forward references: integer types <stdint.h> (7.20).
-    5.2.4.2.1 Sizes of integer types <limits.h>
-1   The values given below shall be replaced by constant expressions suitable for use in #if
-    preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the
-    following shall be replaced by expressions that have the same type as would an
-    expression that is an object of the corresponding type converted according to the integer
-    promotions. Their implementation-defined values shall be equal or greater in magnitude
-
-
-    19) See ''future language directions'' (6.11.3).
-
-[page 26] (Contents)
-
-(absolute value) to those shown, with the same sign.
--- number of bits for smallest object that is not a bit-field (byte)
-  CHAR_BIT                                            8
--- minimum value for an object of type signed char
-  SCHAR_MIN                                -127 // -(27 - 1)
--- maximum value for an object of type signed char
-  SCHAR_MAX                                +127 // 27 - 1
--- maximum value for an object of type unsigned char
-  UCHAR_MAX                                 255 // 28 - 1
--- minimum value for an object of type char
-  CHAR_MIN                               see below
--- maximum value for an object of type char
-  CHAR_MAX                              see below
--- maximum number of bytes in a multibyte character, for any supported locale
-  MB_LEN_MAX                                    1
--- minimum value for an object of type short int
-  SHRT_MIN                               -32767 // -(215 - 1)
--- maximum value for an object of type short int
-  SHRT_MAX                               +32767 // 215 - 1
--- maximum value for an object of type unsigned short int
-  USHRT_MAX                               65535 // 216 - 1
--- minimum value for an object of type int
-  INT_MIN                                 -32767 // -(215 - 1)
--- maximum value for an object of type int
-  INT_MAX                                +32767 // 215 - 1
--- maximum value for an object of type unsigned int
-  UINT_MAX                                65535 // 216 - 1
--- minimum value for an object of type long int
-  LONG_MIN                         -2147483647 // -(231 - 1)
--- maximum value for an object of type long int
-  LONG_MAX                         +2147483647 // 231 - 1
--- maximum value for an object of type unsigned long int
-  ULONG_MAX                         4294967295 // 232 - 1
-
-
-[page 27] (Contents)
-
-    -- minimum value for an object of type long long int
-      LLONG_MIN          -9223372036854775807 // -(263 - 1)
-    -- maximum value for an object of type long long int
-      LLONG_MAX          +9223372036854775807 // 263 - 1
-    -- maximum value for an object of type unsigned long long int
-      ULLONG_MAX         18446744073709551615 // 264 - 1
-2   If the value of an object of type char is treated as a signed integer when used in an
-    expression, the value of CHAR_MIN shall be the same as that of SCHAR_MIN and the
-    value of CHAR_MAX shall be the same as that of SCHAR_MAX. Otherwise, the value of
-    CHAR_MIN shall be 0 and the value of CHAR_MAX shall be the same as that of
-    UCHAR_MAX.20) The value UCHAR_MAX shall equal 2CHAR_BIT - 1.
-    Forward references: representations of types (6.2.6), conditional inclusion (6.10.1).
-    5.2.4.2.2 Characteristics of floating types <float.h>
-1   The characteristics of floating types are defined in terms of a model that describes a
-    representation of floating-point numbers and values that provide information about an
-    implementation's floating-point arithmetic.21) The following parameters are used to
-    define the model for each floating-point type:
-           s          sign ((+-)1)
-           b          base or radix of exponent representation (an integer > 1)
-           e          exponent (an integer between a minimum emin and a maximum emax )
-           p          precision (the number of base-b digits in the significand)
-            fk        nonnegative integers less than b (the significand digits)
-2   A floating-point number (x) is defined by the following model:
-                       p
-           x = sb e   (Sum) f k b-k ,
-                      k=1
-                                    emin <= e <= emax
-
-3   In addition to normalized floating-point numbers ( f 1 > 0 if x != 0), floating types may be
-    able to contain other kinds of floating-point numbers, such as subnormal floating-point
-    numbers (x != 0, e = emin , f 1 = 0) and unnormalized floating-point numbers (x != 0,
-    e > emin , f 1 = 0), and values that are not floating-point numbers, such as infinities and
-    NaNs. A NaN is an encoding signifying Not-a-Number. A quiet NaN propagates
-    through almost every arithmetic operation without raising a floating-point exception; a
-    signaling NaN generally raises a floating-point exception when occurring as an
-
-
-    20) See 6.2.5.
-    21) The floating-point model is intended to clarify the description of each floating-point characteristic and
-        does not require the floating-point arithmetic of the implementation to be identical.
-
-[page 28] (Contents)
-
-    arithmetic operand.22)
-4   An implementation may give zero and non-numeric values (such as infinities and NaNs) a
-    sign or may leave them unsigned. Wherever such values are unsigned, any requirement
-    in this International Standard to retrieve the sign shall produce an unspecified sign, and
-    any requirement to set the sign shall be ignored.
-5   The minimum range of representable values for a floating type is the most negative finite
-    floating-point number representable in that type through the most positive finite floating-
-    point number representable in that type. In addition, if negative infinity is representable
-    in a type, the range of that type is extended to all negative real numbers; likewise, if
-    positive infinity is representable in a type, the range of that type is extended to all positive
-    real numbers.
-6   The accuracy of the floating-point operations (+, -, *, /) and of the library functions in
-    <math.h> and <complex.h> that return floating-point results is implementation-
-    defined, as is the accuracy of the conversion between floating-point internal
-    representations and string representations performed by the library functions in
-    <stdio.h>, <stdlib.h>, and <wchar.h>. The implementation may state that the
-    accuracy is unknown.
-7   All integer values in the <float.h> header, except FLT_ROUNDS, shall be constant
-    expressions suitable for use in #if preprocessing directives; all floating values shall be
-    constant expressions. All except DECIMAL_DIG, FLT_EVAL_METHOD, FLT_RADIX,
-    and FLT_ROUNDS have separate names for all three floating-point types. The floating-
-    point model representation is provided for all values except FLT_EVAL_METHOD and
-    FLT_ROUNDS.
-8   The rounding mode for floating-point addition is characterized by the implementation-
-    defined value of FLT_ROUNDS:23)
-          -1      indeterminable
-           0      toward zero
-           1      to nearest
-           2      toward positive infinity
-           3      toward negative infinity
-    All other values for FLT_ROUNDS characterize implementation-defined rounding
-    behavior.
-
-
-    22) IEC 60559:1989 specifies quiet and signaling NaNs. For implementations that do not support
-        IEC 60559:1989, the terms quiet NaN and signaling NaN are intended to apply to encodings with
-        similar behavior.
-    23) Evaluation of FLT_ROUNDS correctly reflects any execution-time change of rounding mode through
-        the function fesetround in <fenv.h>.
-
-[page 29] (Contents)
-
-9    Except for assignment and cast (which remove all extra range and precision), the values
-     yielded by operators with floating operands and values subject to the usual arithmetic
-     conversions and of floating constants are evaluated to a format whose range and precision
-     may be greater than required by the type. The use of evaluation formats is characterized
-     by the implementation-defined value of FLT_EVAL_METHOD:24)
-            -1         indeterminable;
-              0        evaluate all operations and constants just to the range and precision of the
-                       type;
-              1        evaluate operations and constants of type float and double to the
-                       range and precision of the double type, evaluate long double
-                       operations and constants to the range and precision of the long double
-                       type;
-              2        evaluate all operations and constants to the range and precision of the
-                       long double type.
-     All other negative values for FLT_EVAL_METHOD characterize implementation-defined
-     behavior.
-10   The presence or absence of subnormal numbers is characterized by the implementation-
-     defined     values     of    FLT_HAS_SUBNORM,          DBL_HAS_SUBNORM,           and
-     LDBL_HAS_SUBNORM:
-            -1       indeterminable25)
-             0       absent26) (type does not support subnormal numbers)
-             1       present (type does support subnormal numbers)
-11   The values given in the following list shall be replaced by constant expressions with
-     implementation-defined values that are greater or equal in magnitude (absolute value) to
-     those shown, with the same sign:
-     -- radix of exponent representation, b
-       FLT_RADIX                                                    2
-
-
-
-
-     24) The evaluation method determines evaluation formats of expressions involving all floating types, not
-         just real types. For example, if FLT_EVAL_METHOD is 1, then the product of two float
-         _Complex operands is represented in the double _Complex format, and its parts are evaluated to
-         double.
-     25) Characterization as indeterminable is intended if floating-point operations do not consistently interpret
-         subnormal representations as zero, nor as nonzero.
-     26) Characterization as absent is intended if no floating-point operations produce subnormal results from
-         non-subnormal inputs, even if the type format includes representations of subnormal numbers.
-
-[page 30] (Contents)
-
--- number of base-FLT_RADIX digits in the floating-point significand, p
-   FLT_MANT_DIG
-   DBL_MANT_DIG
-   LDBL_MANT_DIG
--- number of decimal digits, n, such that any floating-point number with p radix b digits
-  can be rounded to a floating-point number with n decimal digits and back again
-  without change to the value,
-       { p log10 b        if b is a power of 10
-       {
-       { [^1 + p log10 b^] otherwise
-   FLT_DECIMAL_DIG                                   6
-   DBL_DECIMAL_DIG                                  10
-   LDBL_DECIMAL_DIG                                 10
--- number of decimal digits, n, such that any floating-point number in the widest
-  supported floating type with pmax radix b digits can be rounded to a floating-point
-  number with n decimal digits and back again without change to the value,
-       { pmax log10 b       if b is a power of 10
-       {
-       { [^1 + pmax log10 b^] otherwise
-   DECIMAL_DIG                                     10
--- number of decimal digits, q, such that any floating-point number with q decimal digits
-  can be rounded into a floating-point number with p radix b digits and back again
-  without change to the q decimal digits,
-       { p log10 b          if b is a power of 10
-       {
-       { [_( p - 1) log10 b_] otherwise
-   FLT_DIG                                          6
-   DBL_DIG                                         10
-   LDBL_DIG                                        10
--- minimum negative integer such that FLT_RADIX raised to one less than that power is
-  a normalized floating-point number, emin
-   FLT_MIN_EXP
-   DBL_MIN_EXP
-   LDBL_MIN_EXP
-
-
-
-
-[page 31] (Contents)
-
-     -- minimum negative integer such that 10 raised to that power is in the range of
-       normalized floating-point numbers, [^log10 b emin -1 ^]
-                                         [                  ]
-       FLT_MIN_10_EXP                                 -37
-       DBL_MIN_10_EXP                                 -37
-       LDBL_MIN_10_EXP                                -37
-     -- maximum integer such that FLT_RADIX raised to one less than that power is a
-       representable finite floating-point number, emax
-          FLT_MAX_EXP
-          DBL_MAX_EXP
-          LDBL_MAX_EXP
-     -- maximum integer such that 10 raised to that power is in the range of representable
-       finite floating-point numbers, [_log10 ((1 - b- p )b emax )_]
-          FLT_MAX_10_EXP                               +37
-          DBL_MAX_10_EXP                               +37
-          LDBL_MAX_10_EXP                              +37
-12   The values given in the following list shall be replaced by constant expressions with
-     implementation-defined values that are greater than or equal to those shown:
-     -- maximum representable finite floating-point number, (1 - b- p )b emax
-          FLT_MAX                                   1E+37
-          DBL_MAX                                   1E+37
-          LDBL_MAX                                  1E+37
-13   The values given in the following list shall be replaced by constant expressions with
-     implementation-defined (positive) values that are less than or equal to those shown:
-     -- the difference between 1 and the least value greater than 1 that is representable in the
-       given floating point type, b1- p
-          FLT_EPSILON                                1E-5
-          DBL_EPSILON                                1E-9
-          LDBL_EPSILON                               1E-9
-     -- minimum normalized positive floating-point number, b emin -1
-          FLT_MIN                                   1E-37
-          DBL_MIN                                   1E-37
-          LDBL_MIN                                  1E-37
-
-
-
-
-[page 32] (Contents)
-
-     -- minimum positive floating-point number27)
-         FLT_TRUE_MIN                                       1E-37
-         DBL_TRUE_MIN                                       1E-37
-         LDBL_TRUE_MIN                                      1E-37
-     Recommended practice
-14   Conversion from (at least) double to decimal with DECIMAL_DIG digits and back
-     should be the identity function.
-15   EXAMPLE 1 The following describes an artificial floating-point representation that meets the minimum
-     requirements of this International Standard, and the appropriate values in a <float.h> header for type
-     float:
-                        6
-           x = s16e    (Sum) f k 16-k ,
-                       k=1
-                                       -31 <= e <= +32
-
-             FLT_RADIX                                    16
-             FLT_MANT_DIG                                  6
-             FLT_EPSILON                     9.53674316E-07F
-             FLT_DECIMAL_DIG                               9
-             FLT_DIG                                       6
-             FLT_MIN_EXP                                 -31
-             FLT_MIN                         2.93873588E-39F
-             FLT_MIN_10_EXP                              -38
-             FLT_MAX_EXP                                 +32
-             FLT_MAX                         3.40282347E+38F
-             FLT_MAX_10_EXP                              +38
-
-16   EXAMPLE 2 The following describes floating-point representations that also meet the requirements for
-     single-precision and double-precision numbers in IEC 60559,28) and the appropriate values in a
-     <float.h> header for types float and double:
-                       24
-           x f = s2e   (Sum) f k 2-k ,
-                       k=1
-                                      -125 <= e <= +128
-
-                       53
-           x d = s2e   (Sum) f k 2-k ,
-                       k=1
-                                      -1021 <= e <= +1024
-
-             FLT_RADIX                                     2
-             DECIMAL_DIG                                  17
-             FLT_MANT_DIG                                 24
-             FLT_EPSILON                     1.19209290E-07F // decimal constant
-             FLT_EPSILON                            0X1P-23F // hex constant
-             FLT_DECIMAL_DIG                               9
-
-
-     27) If the presence or absence of subnormal numbers is indeterminable, then the value is intended to be a
-         positive number no greater than the minimum normalized positive number for the type.
-     28) The floating-point model in that standard sums powers of b from zero, so the values of the exponent
-         limits are one less than shown here.
-
-[page 33] (Contents)
-
-        FLT_DIG                             6
-        FLT_MIN_EXP                      -125
-        FLT_MIN               1.17549435E-38F               //   decimal constant
-        FLT_MIN                     0X1P-126F               //   hex constant
-        FLT_TRUE_MIN          1.40129846E-45F               //   decimal constant
-        FLT_TRUE_MIN                0X1P-149F               //   hex constant
-        FLT_HAS_SUBNORM                     1
-        FLT_MIN_10_EXP                    -37
-        FLT_MAX_EXP                      +128
-        FLT_MAX               3.40282347E+38F               // decimal constant
-        FLT_MAX               0X1.fffffeP127F               // hex constant
-        FLT_MAX_10_EXP                    +38
-        DBL_MANT_DIG                       53
-        DBL_EPSILON    2.2204460492503131E-16               // decimal constant
-        DBL_EPSILON                   0X1P-52               // hex constant
-        DBL_DECIMAL_DIG                    17
-        DBL_DIG                            15
-        DBL_MIN_EXP                     -1021
-        DBL_MIN      2.2250738585072014E-308                //   decimal constant
-        DBL_MIN                     0X1P-1022               //   hex constant
-        DBL_TRUE_MIN 4.9406564584124654E-324                //   decimal constant
-        DBL_TRUE_MIN                0X1P-1074               //   hex constant
-        DBL_HAS_SUBNORM                     1
-        DBL_MIN_10_EXP                   -307
-        DBL_MAX_EXP                     +1024
-        DBL_MAX      1.7976931348623157E+308                // decimal constant
-        DBL_MAX        0X1.fffffffffffffP1023               // hex constant
-        DBL_MAX_10_EXP                   +308
-If a type wider than double were supported, then DECIMAL_DIG would be greater than 17. For
-example, if the widest type were to use the minimal-width IEC 60559 double-extended format (64 bits of
-precision), then DECIMAL_DIG would be 21.
-
-Forward references:        conditional inclusion (6.10.1), complex arithmetic
-<complex.h> (7.3), extended multibyte and wide character utilities <wchar.h>
-(7.28), floating-point environment <fenv.h> (7.6), general utilities <stdlib.h>
-(7.22), input/output <stdio.h> (7.21), mathematics <math.h> (7.12).
-
-
-
-
-[page 34] (Contents)
-
-
-    6. Language
-    6.1 Notation
-1   In the syntax notation used in this clause, syntactic categories (nonterminals) are
-    indicated by italic type, and literal words and character set members (terminals) by bold
-    type. A colon (:) following a nonterminal introduces its definition. Alternative
-    definitions are listed on separate lines, except when prefaced by the words ''one of''. An
-    optional symbol is indicated by the subscript ''opt'', so that
-             { expressionopt }
-    indicates an optional expression enclosed in braces.
-2   When syntactic categories are referred to in the main text, they are not italicized and
-    words are separated by spaces instead of hyphens.
-3   A summary of the language syntax is given in annex A.
-    6.2 Concepts
-    6.2.1 Scopes of identifiers
-1   An identifier can denote an object; a function; a tag or a member of a structure, union, or
-    enumeration; a typedef name; a label name; a macro name; or a macro parameter. The
-    same identifier can denote different entities at different points in the program. A member
-    of an enumeration is called an enumeration constant. Macro names and macro
-    parameters are not considered further here, because prior to the semantic phase of
-    program translation any occurrences of macro names in the source file are replaced by the
-    preprocessing token sequences that constitute their macro definitions.
-2   For each different entity that an identifier designates, the identifier is visible (i.e., can be
-    used) only within a region of program text called its scope. Different entities designated
-    by the same identifier either have different scopes, or are in different name spaces. There
-    are four kinds of scopes: function, file, block, and function prototype. (A function
-    prototype is a declaration of a function that declares the types of its parameters.)
-3   A label name is the only kind of identifier that has function scope. It can be used (in a
-    goto statement) anywhere in the function in which it appears, and is declared implicitly
-    by its syntactic appearance (followed by a : and a statement).
-4   Every other identifier has scope determined by the placement of its declaration (in a
-    declarator or type specifier). If the declarator or type specifier that declares the identifier
-    appears outside of any block or list of parameters, the identifier has file scope, which
-    terminates at the end of the translation unit. If the declarator or type specifier that
-    declares the identifier appears inside a block or within the list of parameter declarations in
-    a function definition, the identifier has block scope, which terminates at the end of the
-    associated block. If the declarator or type specifier that declares the identifier appears
-
-[page 35] (Contents)
-
-    within the list of parameter declarations in a function prototype (not part of a function
-    definition), the identifier has function prototype scope, which terminates at the end of the
-    function declarator. If an identifier designates two different entities in the same name
-    space, the scopes might overlap. If so, the scope of one entity (the inner scope) will end
-    strictly before the scope of the other entity (the outer scope). Within the inner scope, the
-    identifier designates the entity declared in the inner scope; the entity declared in the outer
-    scope is hidden (and not visible) within the inner scope.
-5   Unless explicitly stated otherwise, where this International Standard uses the term
-    ''identifier'' to refer to some entity (as opposed to the syntactic construct), it refers to the
-    entity in the relevant name space whose declaration is visible at the point the identifier
-    occurs.
-6   Two identifiers have the same scope if and only if their scopes terminate at the same
-    point.
-7   Structure, union, and enumeration tags have scope that begins just after the appearance of
-    the tag in a type specifier that declares the tag. Each enumeration constant has scope that
-    begins just after the appearance of its defining enumerator in an enumerator list. Any
-    other identifier has scope that begins just after the completion of its declarator.
-8   As a special case, a type name (which is not a declaration of an identifier) is considered to
-    have a scope that begins just after the place within the type name where the omitted
-    identifier would appear were it not omitted.
-    Forward references: declarations (6.7), function calls (6.5.2.2), function definitions
-    (6.9.1), identifiers (6.4.2), macro replacement (6.10.3), name spaces of identifiers (6.2.3),
-    source file inclusion (6.10.2), statements (6.8).
-    6.2.2 Linkages of identifiers
-1   An identifier declared in different scopes or in the same scope more than once can be
-    made to refer to the same object or function by a process called linkage.29) There are
-    three kinds of linkage: external, internal, and none.
-2   In the set of translation units and libraries that constitutes an entire program, each
-    declaration of a particular identifier with external linkage denotes the same object or
-    function. Within one translation unit, each declaration of an identifier with internal
-    linkage denotes the same object or function. Each declaration of an identifier with no
-    linkage denotes a unique entity.
-3   If the declaration of a file scope identifier for an object or a function contains the storage-
-    class specifier static, the identifier has internal linkage.30)
-
-
-
-    29) There is no linkage between different identifiers.
-
-[page 36] (Contents)
-
-4   For an identifier declared with the storage-class specifier extern in a scope in which a
-    prior declaration of that identifier is visible,31) if the prior declaration specifies internal or
-    external linkage, the linkage of the identifier at the later declaration is the same as the
-    linkage specified at the prior declaration. If no prior declaration is visible, or if the prior
-    declaration specifies no linkage, then the identifier has external linkage.
-5   If the declaration of an identifier for a function has no storage-class specifier, its linkage
-    is determined exactly as if it were declared with the storage-class specifier extern. If
-    the declaration of an identifier for an object has file scope and no storage-class specifier,
-    its linkage is external.
-6   The following identifiers have no linkage: an identifier declared to be anything other than
-    an object or a function; an identifier declared to be a function parameter; a block scope
-    identifier for an object declared without the storage-class specifier extern.
-7   If, within a translation unit, the same identifier appears with both internal and external
-    linkage, the behavior is undefined.
-    Forward references: declarations (6.7), expressions (6.5), external definitions (6.9),
-    statements (6.8).
-    6.2.3 Name spaces of identifiers
-1   If more than one declaration of a particular identifier is visible at any point in a
-    translation unit, the syntactic context disambiguates uses that refer to different entities.
-    Thus, there are separate name spaces for various categories of identifiers, as follows:
-    -- label names (disambiguated by the syntax of the label declaration and use);
-    -- the tags of structures, unions, and enumerations (disambiguated by following any32)
-      of the keywords struct, union, or enum);
-    -- the members of structures or unions; each structure or union has a separate name
-      space for its members (disambiguated by the type of the expression used to access the
-      member via the . or -> operator);
-    -- all other identifiers, called ordinary identifiers (declared in ordinary declarators or as
-      enumeration constants).
-    Forward references: enumeration specifiers (6.7.2.2), labeled statements (6.8.1),
-    structure and union specifiers (6.7.2.1), structure and union members (6.5.2.3), tags
-    (6.7.2.3), the goto statement (6.8.6.1).
-
-    30) A function declaration can contain the storage-class specifier static only if it is at file scope; see
-        6.7.1.
-    31) As specified in 6.2.1, the later declaration might hide the prior declaration.
-    32) There is only one name space for tags even though three are possible.
-
-[page 37] (Contents)
-
-    6.2.4 Storage durations of objects
-1   An object has a storage duration that determines its lifetime. There are four storage
-    durations: static, thread, automatic, and allocated. Allocated storage is described in
-    7.22.3.
-2   The lifetime of an object is the portion of program execution during which storage is
-    guaranteed to be reserved for it. An object exists, has a constant address,33) and retains
-    its last-stored value throughout its lifetime.34) If an object is referred to outside of its
-    lifetime, the behavior is undefined. The value of a pointer becomes indeterminate when
-    the object it points to (or just past) reaches the end of its lifetime.
-3   An object whose identifier is declared without the storage-class specifier
-    _Thread_local, and either with external or internal linkage or with the storage-class
-    specifier static, has static storage duration. Its lifetime is the entire execution of the
-    program and its stored value is initialized only once, prior to program startup.
-4   An object whose identifier is declared with the storage-class specifier _Thread_local
-    has thread storage duration. Its lifetime is the entire execution of the thread for which it
-    is created, and its stored value is initialized when the thread is started. There is a distinct
-    object per thread, and use of the declared name in an expression refers to the object
-    associated with the thread evaluating the expression. The result of attempting to
-    indirectly access an object with thread storage duration from a thread other than the one
-    with which the object is associated is implementation-defined.
-5   An object whose identifier is declared with no linkage and without the storage-class
-    specifier static has automatic storage duration, as do some compound literals. The
-    result of attempting to indirectly access an object with automatic storage duration from a
-    thread other than the one with which the object is associated is implementation-defined.
-6   For such an object that does not have a variable length array type, its lifetime extends
-    from entry into the block with which it is associated until execution of that block ends in
-    any way. (Entering an enclosed block or calling a function suspends, but does not end,
-    execution of the current block.) If the block is entered recursively, a new instance of the
-    object is created each time. The initial value of the object is indeterminate. If an
-    initialization is specified for the object, it is performed each time the declaration or
-    compound literal is reached in the execution of the block; otherwise, the value becomes
-    indeterminate each time the declaration is reached.
-
-
-
-    33) The term ''constant address'' means that two pointers to the object constructed at possibly different
-        times will compare equal. The address may be different during two different executions of the same
-        program.
-    34) In the case of a volatile object, the last store need not be explicit in the program.
-
-[page 38] (Contents)
-
-7   For such an object that does have a variable length array type, its lifetime extends from
-    the declaration of the object until execution of the program leaves the scope of the
-    declaration.35) If the scope is entered recursively, a new instance of the object is created
-    each time. The initial value of the object is indeterminate.
-8   A non-lvalue expression with structure or union type, where the structure or union
-    contains a member with array type (including, recursively, members of all contained
-    structures and unions) refers to an object with automatic storage duration and temporary
-    lifetime.36) Its lifetime begins when the expression is evaluated and its initial value is the
-    value of the expression. Its lifetime ends when the evaluation of the containing full
-    expression or full declarator ends. Any attempt to modify an object with temporary
-    lifetime results in undefined behavior.
-    Forward references: array declarators (6.7.6.2), compound literals (6.5.2.5), declarators
-    (6.7.6), function calls (6.5.2.2), initialization (6.7.9), statements (6.8).
-    6.2.5 Types
-1   The meaning of a value stored in an object or returned by a function is determined by the
-    type of the expression used to access it. (An identifier declared to be an object is the
-    simplest such expression; the type is specified in the declaration of the identifier.) Types
-    are partitioned into object types (types that describe objects) and function types (types
-    that describe functions). At various points within a translation unit an object type may be
-    incomplete (lacking sufficient information to determine the size of objects of that type) or
-    complete (having sufficient information).37)
-2   An object declared as type _Bool is large enough to store the values 0 and 1.
-3   An object declared as type char is large enough to store any member of the basic
-    execution character set. If a member of the basic execution character set is stored in a
-    char object, its value is guaranteed to be nonnegative. If any other character is stored in
-    a char object, the resulting value is implementation-defined but shall be within the range
-    of values that can be represented in that type.
-4   There are five standard signed integer types, designated as signed char, short
-    int, int, long int, and long long int. (These and other types may be
-    designated in several additional ways, as described in 6.7.2.) There may also be
-    implementation-defined extended signed integer types.38) The standard and extended
-    signed integer types are collectively called signed integer types.39)
-
-    35) Leaving the innermost block containing the declaration, or jumping to a point in that block or an
-        embedded block prior to the declaration, leaves the scope of the declaration.
-    36) The address of such an object is taken implicitly when an array member is accessed.
-    37) A type may be incomplete or complete throughout an entire translation unit, or it may change states at
-        different points within a translation unit.
-
-[page 39] (Contents)
-
-5    An object declared as type signed char occupies the same amount of storage as a
-     ''plain'' char object. A ''plain'' int object has the natural size suggested by the
-     architecture of the execution environment (large enough to contain any value in the range
-     INT_MIN to INT_MAX as defined in the header <limits.h>).
-6    For each of the signed integer types, there is a corresponding (but different) unsigned
-     integer type (designated with the keyword unsigned) that uses the same amount of
-     storage (including sign information) and has the same alignment requirements. The type
-     _Bool and the unsigned integer types that correspond to the standard signed integer
-     types are the standard unsigned integer types. The unsigned integer types that
-     correspond to the extended signed integer types are the extended unsigned integer types.
-     The standard and extended unsigned integer types are collectively called unsigned integer
-     types.40)
-7    The standard signed integer types and standard unsigned integer types are collectively
-     called the standard integer types, the extended signed integer types and extended
-     unsigned integer types are collectively called the extended integer types.
-8    For any two integer types with the same signedness and different integer conversion rank
-     (see 6.3.1.1), the range of values of the type with smaller integer conversion rank is a
-     subrange of the values of the other type.
-9    The range of nonnegative values of a signed integer type is a subrange of the
-     corresponding unsigned integer type, and the representation of the same value in each
-     type is the same.41) A computation involving unsigned operands can never overflow,
-     because a result that cannot be represented by the resulting unsigned integer type is
-     reduced modulo the number that is one greater than the largest value that can be
-     represented by the resulting type.
-10   There are three real floating types, designated as float, double, and long
-     double.42) The set of values of the type float is a subset of the set of values of the
-     type double; the set of values of the type double is a subset of the set of values of the
-     type long double.
-
-
-     38) Implementation-defined keywords shall have the form of an identifier reserved for any use as
-         described in 7.1.3.
-     39) Therefore, any statement in this Standard about signed integer types also applies to the extended
-         signed integer types.
-     40) Therefore, any statement in this Standard about unsigned integer types also applies to the extended
-         unsigned integer types.
-     41) The same representation and alignment requirements are meant to imply interchangeability as
-         arguments to functions, return values from functions, and members of unions.
-     42) See ''future language directions'' (6.11.1).
-
-[page 40] (Contents)
-
-11   There are three complex types, designated as float _Complex, double
-     _Complex, and long double _Complex.43) (Complex types are a conditional
-     feature that implementations need not support; see 6.10.8.3.) The real floating and
-     complex types are collectively called the floating types.
-12   For each floating type there is a corresponding real type, which is always a real floating
-     type. For real floating types, it is the same type. For complex types, it is the type given
-     by deleting the keyword _Complex from the type name.
-13   Each complex type has the same representation and alignment requirements as an array
-     type containing exactly two elements of the corresponding real type; the first element is
-     equal to the real part, and the second element to the imaginary part, of the complex
-     number.
-14   The type char, the signed and unsigned integer types, and the floating types are
-     collectively called the basic types. The basic types are complete object types. Even if the
-     implementation defines two or more basic types to have the same representation, they are
-     nevertheless different types.44)
-15   The three types char, signed char, and unsigned char are collectively called
-     the character types. The implementation shall define char to have the same range,
-     representation, and behavior as either signed char or unsigned char.45)
-16   An enumeration comprises a set of named integer constant values. Each distinct
-     enumeration constitutes a different enumerated type.
-17   The type char, the signed and unsigned integer types, and the enumerated types are
-     collectively called integer types. The integer and real floating types are collectively called
-     real types.
-18   Integer and floating types are collectively called arithmetic types. Each arithmetic type
-     belongs to one type domain: the real type domain comprises the real types, the complex
-     type domain comprises the complex types.
-19   The void type comprises an empty set of values; it is an incomplete object type that
-     cannot be completed.
-
-
-
-     43) A specification for imaginary types is in informative annex G.
-     44) An implementation may define new keywords that provide alternative ways to designate a basic (or
-         any other) type; this does not violate the requirement that all basic types be different.
-         Implementation-defined keywords shall have the form of an identifier reserved for any use as
-         described in 7.1.3.
-     45) CHAR_MIN, defined in <limits.h>, will have one of the values 0 or SCHAR_MIN, and this can be
-         used to distinguish the two options. Irrespective of the choice made, char is a separate type from the
-         other two and is not compatible with either.
-
-[page 41] (Contents)
-
-20   Any number of derived types can be constructed from the object and function types, as
-     follows:
-     -- An array type describes a contiguously allocated nonempty set of objects with a
-       particular member object type, called the element type. The element type shall be
-       complete whenever the array type is specified. Array types are characterized by their
-       element type and by the number of elements in the array. An array type is said to be
-       derived from its element type, and if its element type is T , the array type is sometimes
-       called ''array of T ''. The construction of an array type from an element type is called
-       ''array type derivation''.
-     -- A structure type describes a sequentially allocated nonempty set of member objects
-       (and, in certain circumstances, an incomplete array), each of which has an optionally
-       specified name and possibly distinct type.
-     -- A union type describes an overlapping nonempty set of member objects, each of
-       which has an optionally specified name and possibly distinct type.
-     -- A function type describes a function with specified return type. A function type is
-       characterized by its return type and the number and types of its parameters. A
-       function type is said to be derived from its return type, and if its return type is T , the
-       function type is sometimes called ''function returning T ''. The construction of a
-       function type from a return type is called ''function type derivation''.
-     -- A pointer type may be derived from a function type or an object type, called the
-       referenced type. A pointer type describes an object whose value provides a reference
-       to an entity of the referenced type. A pointer type derived from the referenced type T
-       is sometimes called ''pointer to T ''. The construction of a pointer type from a
-       referenced type is called ''pointer type derivation''. A pointer type is a complete
-       object type.
-     These methods of constructing derived types can be applied recursively.
-21   Arithmetic types and pointer types are collectively called scalar types. Array and
-     structure types are collectively called aggregate types.46)
-22   An array type of unknown size is an incomplete type. It is completed, for an identifier of
-     that type, by specifying the size in a later declaration (with internal or external linkage).
-     A structure or union type of unknown content (as described in 6.7.2.3) is an incomplete
-     type. It is completed, for all declarations of that type, by declaring the same structure or
-     union tag with its defining content later in the same scope.
-
-
-
-
-     46) Note that aggregate type does not include union type because an object with union type can only
-         contain one member at a time.
-
-[page 42] (Contents)
-
-23   A type has known constant size if the type is not incomplete and is not a variable length
-     array type.
-24   Array, function, and pointer types are collectively called derived declarator types. A
-     declarator type derivation from a type T is the construction of a derived declarator type
-     from T by the application of an array-type, a function-type, or a pointer-type derivation to
-     T.
-25   A type is characterized by its type category, which is either the outermost derivation of a
-     derived type (as noted above in the construction of derived types), or the type itself if the
-     type consists of no derived types.
-26   Any type so far mentioned is an unqualified type. Each unqualified type has several
-     qualified versions of its type,47) corresponding to the combinations of one, two, or all
-     three of the const, volatile, and restrict qualifiers. The qualified or unqualified
-     versions of a type are distinct types that belong to the same type category and have the
-     same representation and alignment requirements.48) A derived type is not qualified by the
-     qualifiers (if any) of the type from which it is derived.
-27   Further, there is the _Atomic qualifier, which may combine with volatile and
-     restrict. The size, representation, and alignment of an _Atomic-qualified type need
-     not be the same as those of the corresponding unqualified type. (Atomic types are a
-     conditional feature that implementations need not support; see 6.10.8.3.)
-28   A pointer to void shall have the same representation and alignment requirements as a
-     pointer to a character type.48) Similarly, pointers to qualified or unqualified versions of
-     compatible types shall have the same representation and alignment requirements. All
-     pointers to structure types shall have the same representation and alignment requirements
-     as each other. All pointers to union types shall have the same representation and
-     alignment requirements as each other. Pointers to other types need not have the same
-     representation or alignment requirements.
-29   EXAMPLE 1 The type designated as ''float *'' has type ''pointer to float''. Its type category is
-     pointer, not a floating type. The const-qualified version of this type is designated as ''float * const''
-     whereas the type designated as ''const float *'' is not a qualified type -- its type is ''pointer to const-
-     qualified float'' and is a pointer to a qualified type.
-
-30   EXAMPLE 2 The type designated as ''struct tag (*[5])(float)'' has type ''array of pointer to
-     function returning struct tag''. The array has length five and the function has a single parameter of type
-     float. Its type category is array.
-
-     Forward references: compatible type and composite type (6.2.7), declarations (6.7).
-
-
-
-     47) See 6.7.3 regarding qualified array and function types.
-     48) The same representation and alignment requirements are meant to imply interchangeability as
-         arguments to functions, return values from functions, and members of unions.
-
-[page 43] (Contents)
-
-    6.2.6 Representations of types
-    6.2.6.1 General
-1   The representations of all types are unspecified except as stated in this subclause.
-2   Except for bit-fields, objects are composed of contiguous sequences of one or more bytes,
-    the number, order, and encoding of which are either explicitly specified or
-    implementation-defined.
-3   Values stored in unsigned bit-fields and objects of type unsigned char shall be
-    represented using a pure binary notation.49)
-4   Values stored in non-bit-field objects of any other object type consist of n x CHAR_BIT
-    bits, where n is the size of an object of that type, in bytes. The value may be copied into
-    an object of type unsigned char [n] (e.g., by memcpy); the resulting set of bytes is
-    called the object representation of the value. Values stored in bit-fields consist of m bits,
-    where m is the size specified for the bit-field. The object representation is the set of m
-    bits the bit-field comprises in the addressable storage unit holding it. Two values (other
-    than NaNs) with the same object representation compare equal, but values that compare
-    equal may have different object representations.
-5   Certain object representations need not represent a value of the object type. If the stored
-    value of an object has such a representation and is read by an lvalue expression that does
-    not have character type, the behavior is undefined. If such a representation is produced
-    by a side effect that modifies all or any part of the object by an lvalue expression that
-    does not have character type, the behavior is undefined.50) Such a representation is called
-    a trap representation.
-6   When a value is stored in an object of structure or union type, including in a member
-    object, the bytes of the object representation that correspond to any padding bytes take
-    unspecified values.51) The value of a structure or union object is never a trap
-    representation, even though the value of a member of the structure or union object may be
-    a trap representation.
-7   When a value is stored in a member of an object of union type, the bytes of the object
-    representation that do not correspond to that member but do correspond to other members
-
-    49) A positional representation for integers that uses the binary digits 0 and 1, in which the values
-        represented by successive bits are additive, begin with 1, and are multiplied by successive integral
-        powers of 2, except perhaps the bit with the highest position. (Adapted from the American National
-        Dictionary for Information Processing Systems.) A byte contains CHAR_BIT bits, and the values of
-        type unsigned char range from 0 to 2
-                                                  CHAR_BIT
-                                                            - 1.
-    50) Thus, an automatic variable can be initialized to a trap representation without causing undefined
-        behavior, but the value of the variable cannot be used until a proper value is stored in it.
-    51) Thus, for example, structure assignment need not copy any padding bits.
-
-[page 44] (Contents)
-
-    take unspecified values.
-8   Where an operator is applied to a value that has more than one object representation,
-    which object representation is used shall not affect the value of the result.52) Where a
-    value is stored in an object using a type that has more than one object representation for
-    that value, it is unspecified which representation is used, but a trap representation shall
-    not be generated.
-9   Loads and stores of objects with _Atomic-qualified types are done with
-    memory_order_seq_cst semantics.
-    Forward references: declarations (6.7), expressions (6.5), lvalues, arrays, and function
-    designators (6.3.2.1), order and consistency (7.17.3).
-    6.2.6.2 Integer types
-1   For unsigned integer types other than unsigned char, the bits of the object
-    representation shall be divided into two groups: value bits and padding bits (there need
-    not be any of the latter). If there are N value bits, each bit shall represent a different
-    power of 2 between 1 and 2 N -1 , so that objects of that type shall be capable of
-    representing values from 0 to 2 N - 1 using a pure binary representation; this shall be
-    known as the value representation. The values of any padding bits are unspecified.53)
-2   For signed integer types, the bits of the object representation shall be divided into three
-    groups: value bits, padding bits, and the sign bit. There need not be any padding bits;
-    signed char shall not have any padding bits. There shall be exactly one sign bit.
-    Each bit that is a value bit shall have the same value as the same bit in the object
-    representation of the corresponding unsigned type (if there are M value bits in the signed
-    type and N in the unsigned type, then M <= N ). If the sign bit is zero, it shall not affect
-    the resulting value. If the sign bit is one, the value shall be modified in one of the
-    following ways:
-    -- the corresponding value with sign bit 0 is negated (sign and magnitude);
-    -- the sign bit has the value -(2 M ) (two's complement);
-
-
-    52) It is possible for objects x and y with the same effective type T to have the same value when they are
-        accessed as objects of type T, but to have different values in other contexts. In particular, if == is
-        defined for type T, then x == y does not imply that memcmp(&x, &y, sizeof (T)) == 0.
-        Furthermore, x == y does not necessarily imply that x and y have the same value; other operations
-        on values of type T may distinguish between them.
-    53) Some combinations of padding bits might generate trap representations, for example, if one padding
-        bit is a parity bit. Regardless, no arithmetic operation on valid values can generate a trap
-        representation other than as part of an exceptional condition such as an overflow, and this cannot occur
-        with unsigned types. All other combinations of padding bits are alternative object representations of
-        the value specified by the value bits.
-
-[page 45] (Contents)
-
-    -- the sign bit has the value -(2 M - 1) (ones' complement).
-    Which of these applies is implementation-defined, as is whether the value with sign bit 1
-    and all value bits zero (for the first two), or with sign bit and all value bits 1 (for ones'
-    complement), is a trap representation or a normal value. In the case of sign and
-    magnitude and ones' complement, if this representation is a normal value it is called a
-    negative zero.
-3   If the implementation supports negative zeros, they shall be generated only by:
-    -- the &, |, ^, ~, <<, and >> operators with operands that produce such a value;
-    -- the +, -, *, /, and % operators where one operand is a negative zero and the result is
-      zero;
-    -- compound assignment operators based on the above cases.
-    It is unspecified whether these cases actually generate a negative zero or a normal zero,
-    and whether a negative zero becomes a normal zero when stored in an object.
-4   If the implementation does not support negative zeros, the behavior of the &, |, ^, ~, <<,
-    and >> operators with operands that would produce such a value is undefined.
-5   The values of any padding bits are unspecified.54) A valid (non-trap) object representation
-    of a signed integer type where the sign bit is zero is a valid object representation of the
-    corresponding unsigned type, and shall represent the same value. For any integer type,
-    the object representation where all the bits are zero shall be a representation of the value
-    zero in that type.
-6   The precision of an integer type is the number of bits it uses to represent values,
-    excluding any sign and padding bits. The width of an integer type is the same but
-    including any sign bit; thus for unsigned integer types the two values are the same, while
-    for signed integer types the width is one greater than the precision.
-
-
-
-
-    54) Some combinations of padding bits might generate trap representations, for example, if one padding
-        bit is a parity bit. Regardless, no arithmetic operation on valid values can generate a trap
-        representation other than as part of an exceptional condition such as an overflow. All other
-        combinations of padding bits are alternative object representations of the value specified by the value
-        bits.
-
-[page 46] (Contents)
-
-    6.2.7 Compatible type and composite type
-1   Two types have compatible type if their types are the same. Additional rules for
-    determining whether two types are compatible are described in 6.7.2 for type specifiers,
-    in 6.7.3 for type qualifiers, and in 6.7.6 for declarators.55) Moreover, two structure,
-    union, or enumerated types declared in separate translation units are compatible if their
-    tags and members satisfy the following requirements: If one is declared with a tag, the
-    other shall be declared with the same tag. If both are completed anywhere within their
-    respective translation units, then the following additional requirements apply: there shall
-    be a one-to-one correspondence between their members such that each pair of
-    corresponding members are declared with compatible types, and such that if one member
-    of a corresponding pair is declared with a name, the other member is declared with the
-    same name. For two structures, corresponding members shall be declared in the same
-    order. For two structures or unions, corresponding bit-fields shall have the same widths.
-    For two enumerations, corresponding members shall have the same values.
-2   All declarations that refer to the same object or function shall have compatible type;
-    otherwise, the behavior is undefined.
-3   A composite type can be constructed from two types that are compatible; it is a type that
-    is compatible with both of the two types and satisfies the following conditions:
-    -- If both types are array types, the following rules are applied:
-          o If one type is an array of known constant size, the composite type is an array of
-             that size.
-          o Otherwise, if one type is a variable length array whose size is specified by an
-             expression that is not evaluated, the behavior is undefined.
-          o Otherwise, if one type is a variable length array whose size is specified, the
-             composite type is a variable length array of that size.
-          o Otherwise, if one type is a variable length array of unspecified size, the composite
-             type is a variable length array of unspecified size.
-          o Otherwise, both types are arrays of unknown size and the composite type is an
-             array of unknown size.
-        The element type of the composite type is the composite type of the two element
-        types.
-    -- If only one type is a function type with a parameter type list (a function prototype),
-      the composite type is a function prototype with the parameter type list.
-
-
-
-    55) Two types need not be identical to be compatible.
-
-[page 47] (Contents)
-
-    -- If both types are function types with parameter type lists, the type of each parameter
-      in the composite parameter type list is the composite type of the corresponding
-      parameters.
-    These rules apply recursively to the types from which the two types are derived.
-4   For an identifier with internal or external linkage declared in a scope in which a prior
-    declaration of that identifier is visible,56) if the prior declaration specifies internal or
-    external linkage, the type of the identifier at the later declaration becomes the composite
-    type.
-    Forward references: array declarators (6.7.6.2).
-5   EXAMPLE        Given the following two file scope declarations:
-             int f(int (*)(), double (*)[3]);
-             int f(int (*)(char *), double (*)[]);
-    The resulting composite type for the function is:
-             int f(int (*)(char *), double (*)[3]);
-
-    6.2.8 Alignment of objects
-1   Complete object types have alignment requirements which place restrictions on the
-    addresses at which objects of that type may be allocated. An alignment is an
-    implementation-defined integer value representing the number of bytes between
-    successive addresses at which a given object can be allocated. An object type imposes an
-    alignment requirement on every object of that type: stricter alignment can be requested
-    using the _Alignas keyword.
-2   A fundamental alignment is represented by an alignment less than or equal to the greatest
-    alignment supported by the implementation in all contexts, which is equal to
-    alignof(max_align_t).
-3   An extended alignment is represented by an alignment greater than
-    alignof(max_align_t). It is implementation-defined whether any extended
-    alignments are supported and the contexts in which they are supported. A type having an
-    extended alignment requirement is an over-aligned type.57)
-4   Alignments are represented as values of the type size_t. Valid alignments include only
-    those values returned by an alignof expression for fundamental types, plus an
-    additional implementation-defined set of values, which may be empty. Every valid
-    alignment value shall be an integral power of two.
-
-
-    56) As specified in 6.2.1, the later declaration might hide the prior declaration.
-    57) Every over-aligned type is, or contains, a structure or union type with a member to which an extended
-        alignment has been applied.
-
-[page 48] (Contents)
-
-5   Alignments have an order from weaker to stronger or stricter alignments. Stricter
-    alignments have larger alignment values. An address that satisfies an alignment
-    requirement also satisfies any weaker valid alignment requirement.
-6   The alignment requirement of a complete type can be queried using an alignof
-    expression. The types char, signed char, and unsigned char shall have the
-    weakest alignment requirement.
-7   Comparing alignments is meaningful and provides the obvious results:
-    -- Two alignments are equal when their numeric values are equal.
-    -- Two alignments are different when their numeric values are not equal.
-    -- When an alignment is larger than another it represents a stricter alignment.
-
-
-
-
-[page 49] (Contents)
-
-    6.3 Conversions
-1   Several operators convert operand values from one type to another automatically. This
-    subclause specifies the result required from such an implicit conversion, as well as those
-    that result from a cast operation (an explicit conversion). The list in 6.3.1.8 summarizes
-    the conversions performed by most ordinary operators; it is supplemented as required by
-    the discussion of each operator in 6.5.
-2   Conversion of an operand value to a compatible type causes no change to the value or the
-    representation.
-    Forward references: cast operators (6.5.4).
-    6.3.1 Arithmetic operands
-    6.3.1.1 Boolean, characters, and integers
-1   Every integer type has an integer conversion rank defined as follows:
-    -- No two signed integer types shall have the same rank, even if they have the same
-      representation.
-    -- The rank of a signed integer type shall be greater than the rank of any signed integer
-      type with less precision.
-    -- The rank of long long int shall be greater than the rank of long int, which
-      shall be greater than the rank of int, which shall be greater than the rank of short
-      int, which shall be greater than the rank of signed char.
-    -- The rank of any unsigned integer type shall equal the rank of the corresponding
-      signed integer type, if any.
-    -- The rank of any standard integer type shall be greater than the rank of any extended
-      integer type with the same width.
-    -- The rank of char shall equal the rank of signed char and unsigned char.
-    -- The rank of _Bool shall be less than the rank of all other standard integer types.
-    -- The rank of any enumerated type shall equal the rank of the compatible integer type
-      (see 6.7.2.2).
-    -- The rank of any extended signed integer type relative to another extended signed
-      integer type with the same precision is implementation-defined, but still subject to the
-      other rules for determining the integer conversion rank.
-    -- For all integer types T1, T2, and T3, if T1 has greater rank than T2 and T2 has
-      greater rank than T3, then T1 has greater rank than T3.
-2   The following may be used in an expression wherever an int or unsigned int may
-    be used:
-
-[page 50] (Contents)
-
-    -- An object or expression with an integer type (other than int or unsigned int)
-      whose integer conversion rank is less than or equal to the rank of int and
-      unsigned int.
-    -- A bit-field of type _Bool, int, signed int, or unsigned int.
-    If an int can represent all values of the original type (as restricted by the width, for a
-    bit-field), the value is converted to an int; otherwise, it is converted to an unsigned
-    int. These are called the integer promotions.58) All other types are unchanged by the
-    integer promotions.
-3   The integer promotions preserve value including sign. As discussed earlier, whether a
-    ''plain'' char is treated as signed is implementation-defined.
-    Forward references: enumeration specifiers (6.7.2.2), structure and union specifiers
-    (6.7.2.1).
-    6.3.1.2 Boolean type
-1   When any scalar value is converted to _Bool, the result is 0 if the value compares equal
-    to 0; otherwise, the result is 1.59)
-    6.3.1.3 Signed and unsigned integers
-1   When a value with integer type is converted to another integer type other than _Bool, if
-    the value can be represented by the new type, it is unchanged.
-2   Otherwise, if the new type is unsigned, the value is converted by repeatedly adding or
-    subtracting one more than the maximum value that can be represented in the new type
-    until the value is in the range of the new type.60)
-3   Otherwise, the new type is signed and the value cannot be represented in it; either the
-    result is implementation-defined or an implementation-defined signal is raised.
-    6.3.1.4 Real floating and integer
-1   When a finite value of real floating type is converted to an integer type other than _Bool,
-    the fractional part is discarded (i.e., the value is truncated toward zero). If the value of
-    the integral part cannot be represented by the integer type, the behavior is undefined.61)
-
-
-    58) The integer promotions are applied only: as part of the usual arithmetic conversions, to certain
-        argument expressions, to the operands of the unary +, -, and ~ operators, and to both operands of the
-        shift operators, as specified by their respective subclauses.
-    59) NaNs do not compare equal to 0 and thus convert to 1.
-    60) The rules describe arithmetic on the mathematical value, not the value of a given type of expression.
-    61) The remaindering operation performed when a value of integer type is converted to unsigned type
-        need not be performed when a value of real floating type is converted to unsigned type. Thus, the
-        range of portable real floating values is (-1, Utype_MAX+1).
-
-[page 51] (Contents)
-
-2   When a value of integer type is converted to a real floating type, if the value being
-    converted can be represented exactly in the new type, it is unchanged. If the value being
-    converted is in the range of values that can be represented but cannot be represented
-    exactly, the result is either the nearest higher or nearest lower representable value, chosen
-    in an implementation-defined manner. If the value being converted is outside the range of
-    values that can be represented, the behavior is undefined.
-    6.3.1.5 Real floating types
-1   When a float is promoted to double or long double, or a double is promoted
-    to long double, its value is unchanged (if the source value is represented in the
-    precision and range of its type).
-2   When a double is demoted to float, a long double is demoted to double or
-    float, or a value being represented in greater precision and range than required by its
-    semantic type (see 6.3.1.8) is explicitly converted (including to its own type), if the value
-    being converted can be represented exactly in the new type, it is unchanged. If the value
-    being converted is in the range of values that can be represented but cannot be
-    represented exactly, the result is either the nearest higher or nearest lower representable
-    value, chosen in an implementation-defined manner. If the value being converted is
-    outside the range of values that can be represented, the behavior is undefined.
-    6.3.1.6 Complex types
-1   When a value of complex type is converted to another complex type, both the real and
-    imaginary parts follow the conversion rules for the corresponding real types.
-    6.3.1.7 Real and complex
-1   When a value of real type is converted to a complex type, the real part of the complex
-    result value is determined by the rules of conversion to the corresponding real type and
-    the imaginary part of the complex result value is a positive zero or an unsigned zero.
-2   When a value of complex type is converted to a real type, the imaginary part of the
-    complex value is discarded and the value of the real part is converted according to the
-    conversion rules for the corresponding real type.
-    6.3.1.8 Usual arithmetic conversions
-1   Many operators that expect operands of arithmetic type cause conversions and yield result
-    types in a similar way. The purpose is to determine a common real type for the operands
-    and result. For the specified operands, each operand is converted, without change of type
-    domain, to a type whose corresponding real type is the common real type. Unless
-    explicitly stated otherwise, the common real type is also the corresponding real type of
-    the result, whose type domain is the type domain of the operands if they are the same,
-    and complex otherwise. This pattern is called the usual arithmetic conversions:
-
-
-[page 52] (Contents)
-
-          First, if the corresponding real type of either operand is long double, the other
-          operand is converted, without change of type domain, to a type whose
-          corresponding real type is long double.
-          Otherwise, if the corresponding real type of either operand is double, the other
-          operand is converted, without change of type domain, to a type whose
-          corresponding real type is double.
-          Otherwise, if the corresponding real type of either operand is float, the other
-          operand is converted, without change of type domain, to a type whose
-          corresponding real type is float.62)
-          Otherwise, the integer promotions are performed on both operands. Then the
-          following rules are applied to the promoted operands:
-                 If both operands have the same type, then no further conversion is needed.
-                 Otherwise, if both operands have signed integer types or both have unsigned
-                 integer types, the operand with the type of lesser integer conversion rank is
-                 converted to the type of the operand with greater rank.
-                 Otherwise, if the operand that has unsigned integer type has rank greater or
-                 equal to the rank of the type of the other operand, then the operand with
-                 signed integer type is converted to the type of the operand with unsigned
-                 integer type.
-                 Otherwise, if the type of the operand with signed integer type can represent
-                 all of the values of the type of the operand with unsigned integer type, then
-                 the operand with unsigned integer type is converted to the type of the
-                 operand with signed integer type.
-                 Otherwise, both operands are converted to the unsigned integer type
-                 corresponding to the type of the operand with signed integer type.
-2   The values of floating operands and of the results of floating expressions may be
-    represented in greater precision and range than that required by the type; the types are not
-    changed thereby.63)
-
-
-
-
-    62) For example, addition of a double _Complex and a float entails just the conversion of the
-        float operand to double (and yields a double _Complex result).
-    63) The cast and assignment operators are still required to perform their specified conversions as
-        described in 6.3.1.4 and 6.3.1.5.
-
-[page 53] (Contents)
-
-    6.3.2 Other operands
-    6.3.2.1 Lvalues, arrays, and function designators
-1   An lvalue is an expression (with an object type other than void) that potentially
-    designates an object;64) if an lvalue does not designate an object when it is evaluated, the
-    behavior is undefined. When an object is said to have a particular type, the type is
-    specified by the lvalue used to designate the object. A modifiable lvalue is an lvalue that
-    does not have array type, does not have an incomplete type, does not have a const-
-    qualified type, and if it is a structure or union, does not have any member (including,
-    recursively, any member or element of all contained aggregates or unions) with a const-
-    qualified type.
-2   Except when it is the operand of the sizeof operator, the unary & operator, the ++
-    operator, the -- operator, or the left operand of the . operator or an assignment operator,
-    an lvalue that does not have array type is converted to the value stored in the designated
-    object (and is no longer an lvalue). If the lvalue has qualified type, the value has the
-    unqualified version of the type of the lvalue; otherwise, the value has the type of the
-    lvalue. If the lvalue has an incomplete type and does not have array type, the behavior is
-    undefined. If the lvalue designates an object of automatic storage duration that could
-    have been declared with the register storage class (never had its address taken), and
-    that object is uninitialized (not declared with an initializer and no assignment to it has
-    been performed prior to use), the behavior is undefined.
-3   Except when it is the operand of the sizeof operator or the unary & operator, or is a
-    string literal used to initialize an array, an expression that has type ''array of type'' is
-    converted to an expression with type ''pointer to type'' that points to the initial element of
-    the array object and is not an lvalue. If the array object has register storage class, the
-    behavior is undefined.
-4   A function designator is an expression that has function type. Except when it is the
-    operand of the sizeof operator65) or the unary & operator, a function designator with
-    type ''function returning type'' is converted to an expression that has type ''pointer to
-    function returning type''.
-    Forward references: address and indirection operators (6.5.3.2), assignment operators
-
-    64) The name ''lvalue'' comes originally from the assignment expression E1 = E2, in which the left
-        operand E1 is required to be a (modifiable) lvalue. It is perhaps better considered as representing an
-        object ''locator value''. What is sometimes called ''rvalue'' is in this International Standard described
-        as the ''value of an expression''.
-         An obvious example of an lvalue is an identifier of an object. As a further example, if E is a unary
-         expression that is a pointer to an object, *E is an lvalue that designates the object to which E points.
-    65) Because this conversion does not occur, the operand of the sizeof operator remains a function
-        designator and violates the constraint in 6.5.3.4.
-
-[page 54] (Contents)
-
-    (6.5.16), common definitions <stddef.h> (7.19), initialization (6.7.9), postfix
-    increment and decrement operators (6.5.2.4), prefix increment and decrement operators
-    (6.5.3.1), the sizeof operator (6.5.3.4), structure and union members (6.5.2.3).
-    6.3.2.2 void
-1   The (nonexistent) value of a void expression (an expression that has type void) shall not
-    be used in any way, and implicit or explicit conversions (except to void) shall not be
-    applied to such an expression. If an expression of any other type is evaluated as a void
-    expression, its value or designator is discarded. (A void expression is evaluated for its
-    side effects.)
-    6.3.2.3 Pointers
-1   A pointer to void may be converted to or from a pointer to any object type. A pointer to
-    any object type may be converted to a pointer to void and back again; the result shall
-    compare equal to the original pointer.
-2   For any qualifier q, a pointer to a non-q-qualified type may be converted to a pointer to
-    the q-qualified version of the type; the values stored in the original and converted pointers
-    shall compare equal.
-3   An integer constant expression with the value 0, or such an expression cast to type
-    void *, is called a null pointer constant.66) If a null pointer constant is converted to a
-    pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal
-    to a pointer to any object or function.
-4   Conversion of a null pointer to another pointer type yields a null pointer of that type.
-    Any two null pointers shall compare equal.
-5   An integer may be converted to any pointer type. Except as previously specified, the
-    result is implementation-defined, might not be correctly aligned, might not point to an
-    entity of the referenced type, and might be a trap representation.67)
-6   Any pointer type may be converted to an integer type. Except as previously specified, the
-    result is implementation-defined. If the result cannot be represented in the integer type,
-    the behavior is undefined. The result need not be in the range of values of any integer
-    type.
-7   A pointer to an object type may be converted to a pointer to a different object type. If the
-    resulting pointer is not correctly aligned68) for the referenced type, the behavior is
-    undefined. Otherwise, when converted back again, the result shall compare equal to the
-
-
-    66) The macro NULL is defined in <stddef.h> (and other headers) as a null pointer constant; see 7.19.
-    67) The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to
-        be consistent with the addressing structure of the execution environment.
-
-[page 55] (Contents)
-
-    original pointer. When a pointer to an object is converted to a pointer to a character type,
-    the result points to the lowest addressed byte of the object. Successive increments of the
-    result, up to the size of the object, yield pointers to the remaining bytes of the object.
-8   A pointer to a function of one type may be converted to a pointer to a function of another
-    type and back again; the result shall compare equal to the original pointer. If a converted
-    pointer is used to call a function whose type is not compatible with the referenced type,
-    the behavior is undefined.
-    Forward references: cast operators (6.5.4), equality operators (6.5.9), integer types
-    capable of holding object pointers (7.20.1.4), simple assignment (6.5.16.1).
-
-
-
-
-    68) In general, the concept ''correctly aligned'' is transitive: if a pointer to type A is correctly aligned for a
-        pointer to type B, which in turn is correctly aligned for a pointer to type C, then a pointer to type A is
-        correctly aligned for a pointer to type C.
-
-[page 56] (Contents)
-
-    6.4 Lexical elements
-    Syntax
-1            token:
-                      keyword
-                      identifier
-                      constant
-                      string-literal
-                      punctuator
-             preprocessing-token:
-                    header-name
-                    identifier
-                    pp-number
-                    character-constant
-                    string-literal
-                    punctuator
-                    each non-white-space character that cannot be one of the above
-    Constraints
-2   Each preprocessing token that is converted to a token shall have the lexical form of a
-    keyword, an identifier, a constant, a string literal, or a punctuator.
-    Semantics
-3   A token is the minimal lexical element of the language in translation phases 7 and 8. The
-    categories of tokens are: keywords, identifiers, constants, string literals, and punctuators.
-    A preprocessing token is the minimal lexical element of the language in translation
-    phases 3 through 6. The categories of preprocessing tokens are: header names,
-    identifiers, preprocessing numbers, character constants, string literals, punctuators, and
-    single non-white-space characters that do not lexically match the other preprocessing
-    token categories.69) If a ' or a " character matches the last category, the behavior is
-    undefined. Preprocessing tokens can be separated by white space; this consists of
-    comments (described later), or white-space characters (space, horizontal tab, new-line,
-    vertical tab, and form-feed), or both. As described in 6.10, in certain circumstances
-    during translation phase 4, white space (or the absence thereof) serves as more than
-    preprocessing token separation. White space may appear within a preprocessing token
-    only as part of a header name or between the quotation characters in a character constant
-    or string literal.
-
-
-
-    69) An additional category, placemarkers, is used internally in translation phase 4 (see 6.10.3.3); it cannot
-        occur in source files.
-
-[page 57] (Contents)
-
-4   If the input stream has been parsed into preprocessing tokens up to a given character, the
-    next preprocessing token is the longest sequence of characters that could constitute a
-    preprocessing token. There is one exception to this rule: header name preprocessing
-    tokens are recognized only within #include preprocessing directives and in
-    implementation-defined locations within #pragma directives. In such contexts, a
-    sequence of characters that could be either a header name or a string literal is recognized
-    as the former.
-5   EXAMPLE 1 The program fragment 1Ex is parsed as a preprocessing number token (one that is not a
-    valid floating or integer constant token), even though a parse as the pair of preprocessing tokens 1 and Ex
-    might produce a valid expression (for example, if Ex were a macro defined as +1). Similarly, the program
-    fragment 1E1 is parsed as a preprocessing number (one that is a valid floating constant token), whether or
-    not E is a macro name.
-
-6   EXAMPLE 2 The program fragment x+++++y is parsed as x ++ ++ + y, which violates a constraint on
-    increment operators, even though the parse x ++ + ++ y might yield a correct expression.
-
-    Forward references: character constants (6.4.4.4), comments (6.4.9), expressions (6.5),
-    floating constants (6.4.4.2), header names (6.4.7), macro replacement (6.10.3), postfix
-    increment and decrement operators (6.5.2.4), prefix increment and decrement operators
-    (6.5.3.1), preprocessing directives (6.10), preprocessing numbers (6.4.8), string literals
-    (6.4.5).
-    6.4.1 Keywords
-    Syntax
-1            keyword: one of
-                   alignof                         goto                         union
-                   auto                            if                           unsigned
-                   break                           inline                       void
-                   case                            int                          volatile
-                   char                            long                         while
-                   const                           register                     _Alignas
-                   continue                        restrict                     _Atomic
-                   default                         return                       _Bool
-                   do                              short                        _Complex
-                   double                          signed                       _Generic
-                   else                            sizeof                       _Imaginary
-                   enum                            static                       _Noreturn
-                   extern                          struct                       _Static_assert
-                   float                           switch                       _Thread_local
-                   for                             typedef
-    Semantics
-2   The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as
-    keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for
-[page 58] (Contents)
-
-    specifying imaginary types.70)
-    6.4.2 Identifiers
-    6.4.2.1 General
-    Syntax
-1            identifier:
-                    identifier-nondigit
-                    identifier identifier-nondigit
-                    identifier digit
-             identifier-nondigit:
-                    nondigit
-                    universal-character-name
-                    other implementation-defined characters
-             nondigit: one of
-                    _ a b            c    d    e    f     g    h    i    j     k    l    m
-                        n o          p    q    r    s     t    u    v    w     x    y    z
-                        A B          C    D    E    F     G    H    I    J     K    L    M
-                        N O          P    Q    R    S     T    U    V    W     X    Y    Z
-             digit: one of
-                    0 1        2     3    4    5    6     7    8    9
-    Semantics
-2   An identifier is a sequence of nondigit characters (including the underscore _, the
-    lowercase and uppercase Latin letters, and other characters) and digits, which designates
-    one or more entities as described in 6.2.1. Lowercase and uppercase letters are distinct.
-    There is no specific limit on the maximum length of an identifier.
-3   Each universal character name in an identifier shall designate a character whose encoding
-    in ISO/IEC 10646 falls into one of the ranges specified in annex D.71) The initial
-    character shall not be a universal character name designating a digit. An implementation
-    may allow multibyte characters that are not part of the basic source character set to
-    appear in identifiers; which characters and their correspondence to universal character
-    names is implementation-defined.
-
-
-
-    70) One possible specification for imaginary types appears in annex G.
-    71) On systems in which linkers cannot accept extended characters, an encoding of the universal character
-        name may be used in forming valid external identifiers. For example, some otherwise unused
-        character or sequence of characters may be used to encode the \u in a universal character name.
-        Extended characters may produce a long external identifier.
-
-[page 59] (Contents)
-
-4   When preprocessing tokens are converted to tokens during translation phase 7, if a
-    preprocessing token could be converted to either a keyword or an identifier, it is converted
-    to a keyword.
-    Implementation limits
-5   As discussed in 5.2.4.1, an implementation may limit the number of significant initial
-    characters in an identifier; the limit for an external name (an identifier that has external
-    linkage) may be more restrictive than that for an internal name (a macro name or an
-    identifier that does not have external linkage). The number of significant characters in an
-    identifier is implementation-defined.
-6   Any identifiers that differ in a significant character are different identifiers. If two
-    identifiers differ only in nonsignificant characters, the behavior is undefined.
-    Forward references: universal character names (6.4.3), macro replacement (6.10.3).
-    6.4.2.2 Predefined identifiers
-    Semantics
-1   The identifier __func__ shall be implicitly declared by the translator as if,
-    immediately following the opening brace of each function definition, the declaration
-             static const char __func__[] = "function-name";
-    appeared, where function-name is the name of the lexically-enclosing function.72)
-2   This name is encoded as if the implicit declaration had been written in the source
-    character set and then translated into the execution character set as indicated in translation
-    phase 5.
-3   EXAMPLE        Consider the code fragment:
-             #include <stdio.h>
-             void myfunc(void)
-             {
-                   printf("%s\n", __func__);
-                   /* ... */
-             }
-    Each time the function is called, it will print to the standard output stream:
-             myfunc
-
-    Forward references: function definitions (6.9.1).
-
-
-
-
-    72) Since the name __func__ is reserved for any use by the implementation (7.1.3), if any other
-        identifier is explicitly declared using the name __func__, the behavior is undefined.
-
-[page 60] (Contents)
-
-    6.4.3 Universal character names
-    Syntax
-1            universal-character-name:
-                    \u hex-quad
-                    \U hex-quad hex-quad
-             hex-quad:
-                    hexadecimal-digit hexadecimal-digit
-                                 hexadecimal-digit hexadecimal-digit
-    Constraints
-2   A universal character name shall not specify a character whose short identifier is less than
-    00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through
-    DFFF inclusive.73)
-    Description
-3   Universal character names may be used in identifiers, character constants, and string
-    literals to designate characters that are not in the basic character set.
-    Semantics
-4   The universal character name \Unnnnnnnn designates the character whose eight-digit
-    short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.74) Similarly, the universal
-    character name \unnnn designates the character whose four-digit short identifier is nnnn
-    (and whose eight-digit short identifier is 0000nnnn).
-
-
-
-
-    73) The disallowed characters are the characters in the basic character set and the code positions reserved
-        by ISO/IEC 10646 for control characters, the character DELETE, and the S-zone (reserved for use by
-        UTF-16).
-
-    74) Short identifiers for characters were first specified in ISO/IEC 10646-1/AMD9:1997.
-
-[page 61] (Contents)
-
-    6.4.4 Constants
-    Syntax
-1            constant:
-                    integer-constant
-                    floating-constant
-                    enumeration-constant
-                    character-constant
-    Constraints
-2   Each constant shall have a type and the value of a constant shall be in the range of
-    representable values for its type.
-    Semantics
-3   Each constant has a type, determined by its form and value, as detailed later.
-    6.4.4.1 Integer constants
-    Syntax
-1            integer-constant:
-                     decimal-constant integer-suffixopt
-                     octal-constant integer-suffixopt
-                     hexadecimal-constant integer-suffixopt
-             decimal-constant:
-                   nonzero-digit
-                   decimal-constant digit
-             octal-constant:
-                    0
-                    octal-constant octal-digit
-             hexadecimal-constant:
-                   hexadecimal-prefix hexadecimal-digit
-                   hexadecimal-constant hexadecimal-digit
-             hexadecimal-prefix: one of
-                   0x 0X
-             nonzero-digit: one of
-                    1 2 3 4          5     6     7   8    9
-             octal-digit: one of
-                     0 1 2 3         4     5     6   7
-
-
-
-
-[page 62] (Contents)
-
-            hexadecimal-digit:    one of
-                  0 1 2            3 4     5    6   7     8   9
-                  a b c            d e     f
-                  A B C            D E     F
-            integer-suffix:
-                    unsigned-suffix long-suffixopt
-                    unsigned-suffix long-long-suffix
-                    long-suffix unsigned-suffixopt
-                    long-long-suffix unsigned-suffixopt
-            unsigned-suffix: one of
-                   u U
-            long-suffix: one of
-                   l L
-            long-long-suffix: one of
-                   ll LL
-    Description
-2   An integer constant begins with a digit, but has no period or exponent part. It may have a
-    prefix that specifies its base and a suffix that specifies its type.
-3   A decimal constant begins with a nonzero digit and consists of a sequence of decimal
-    digits. An octal constant consists of the prefix 0 optionally followed by a sequence of the
-    digits 0 through 7 only. A hexadecimal constant consists of the prefix 0x or 0X followed
-    by a sequence of the decimal digits and the letters a (or A) through f (or F) with values
-    10 through 15 respectively.
-    Semantics
-4   The value of a decimal constant is computed base 10; that of an octal constant, base 8;
-    that of a hexadecimal constant, base 16. The lexically first digit is the most significant.
-5   The type of an integer constant is the first of the corresponding list in which its value can
-    be represented.
-
-
-
-
-[page 63] (Contents)
-
-                                                                     Octal or Hexadecimal
-    Suffix                       Decimal Constant                           Constant
-
-    none                int                                    int
-                        long int                               unsigned int
-                        long long int                          long int
-                                                               unsigned long int
-                                                               long long int
-                                                               unsigned long long int
-
-    u or U              unsigned int                           unsigned int
-                        unsigned long int                      unsigned long int
-                        unsigned long long int                 unsigned long long int
-
-    l or L              long int                               long int
-                        long long int                          unsigned long int
-                                                               long long int
-                                                               unsigned long long int
-
-    Both u or U         unsigned long int                      unsigned long int
-    and l or L          unsigned long long int                 unsigned long long int
-
-    ll or LL            long long int                          long long int
-                                                               unsigned long long int
-
-    Both u or U         unsigned long long int                 unsigned long long int
-    and ll or LL
-6   If an integer constant cannot be represented by any type in its list, it may have an
-    extended integer type, if the extended integer type can represent its value. If all of the
-    types in the list for the constant are signed, the extended integer type shall be signed. If
-    all of the types in the list for the constant are unsigned, the extended integer type shall be
-    unsigned. If the list contains both signed and unsigned types, the extended integer type
-    may be signed or unsigned. If an integer constant cannot be represented by any type in
-    its list and has no extended integer type, then the integer constant has no type.
-
-
-
-
-[page 64] (Contents)
-
-    6.4.4.2 Floating constants
-    Syntax
-1            floating-constant:
-                    decimal-floating-constant
-                    hexadecimal-floating-constant
-             decimal-floating-constant:
-                   fractional-constant exponent-partopt floating-suffixopt
-                   digit-sequence exponent-part floating-suffixopt
-             hexadecimal-floating-constant:
-                   hexadecimal-prefix hexadecimal-fractional-constant
-                                  binary-exponent-part floating-suffixopt
-                   hexadecimal-prefix hexadecimal-digit-sequence
-                                  binary-exponent-part floating-suffixopt
-             fractional-constant:
-                     digit-sequenceopt . digit-sequence
-                     digit-sequence .
-             exponent-part:
-                   e signopt digit-sequence
-                   E signopt digit-sequence
-             sign: one of
-                    + -
-             digit-sequence:
-                     digit
-                     digit-sequence digit
-             hexadecimal-fractional-constant:
-                   hexadecimal-digit-sequenceopt .
-                                  hexadecimal-digit-sequence
-                   hexadecimal-digit-sequence .
-             binary-exponent-part:
-                    p signopt digit-sequence
-                    P signopt digit-sequence
-             hexadecimal-digit-sequence:
-                   hexadecimal-digit
-                   hexadecimal-digit-sequence hexadecimal-digit
-             floating-suffix: one of
-                    f l F L
-
-[page 65] (Contents)
-
-    Description
-2   A floating constant has a significand part that may be followed by an exponent part and a
-    suffix that specifies its type. The components of the significand part may include a digit
-    sequence representing the whole-number part, followed by a period (.), followed by a
-    digit sequence representing the fraction part. The components of the exponent part are an
-    e, E, p, or P followed by an exponent consisting of an optionally signed digit sequence.
-    Either the whole-number part or the fraction part has to be present; for decimal floating
-    constants, either the period or the exponent part has to be present.
-    Semantics
-3   The significand part is interpreted as a (decimal or hexadecimal) rational number; the
-    digit sequence in the exponent part is interpreted as a decimal integer. For decimal
-    floating constants, the exponent indicates the power of 10 by which the significand part is
-    to be scaled. For hexadecimal floating constants, the exponent indicates the power of 2
-    by which the significand part is to be scaled. For decimal floating constants, and also for
-    hexadecimal floating constants when FLT_RADIX is not a power of 2, the result is either
-    the nearest representable value, or the larger or smaller representable value immediately
-    adjacent to the nearest representable value, chosen in an implementation-defined manner.
-    For hexadecimal floating constants when FLT_RADIX is a power of 2, the result is
-    correctly rounded.
-4   An unsuffixed floating constant has type double. If suffixed by the letter f or F, it has
-    type float. If suffixed by the letter l or L, it has type long double.
-5   Floating constants are converted to internal format as if at translation-time. The
-    conversion of a floating constant shall not raise an exceptional condition or a floating-
-    point exception at execution time.
-    Recommended practice
-6   The implementation should produce a diagnostic message if a hexadecimal constant
-    cannot be represented exactly in its evaluation format; the implementation should then
-    proceed with the translation of the program.
-7   The translation-time conversion of floating constants should match the execution-time
-    conversion of character strings by library functions, such as strtod, given matching
-    inputs suitable for both conversions, the same result format, and default execution-time
-    rounding.75)
-
-
-
-
-    75) The specification for the library functions recommends more accurate conversion than required for
-        floating constants (see 7.22.1.3).
-
-[page 66] (Contents)
-
-    6.4.4.3 Enumeration constants
-    Syntax
-1            enumeration-constant:
-                   identifier
-    Semantics
-2   An identifier declared as an enumeration constant has type int.
-    Forward references: enumeration specifiers (6.7.2.2).
-    6.4.4.4 Character constants
-    Syntax
-1            character-constant:
-                    ' c-char-sequence '
-                    L' c-char-sequence '
-                    u' c-char-sequence '
-                    U' c-char-sequence '
-             c-char-sequence:
-                    c-char
-                    c-char-sequence c-char
-             c-char:
-                       any member of the source character set except
-                                    the single-quote ', backslash \, or new-line character
-                       escape-sequence
-             escape-sequence:
-                    simple-escape-sequence
-                    octal-escape-sequence
-                    hexadecimal-escape-sequence
-                    universal-character-name
-             simple-escape-sequence: one of
-                    \' \" \? \\
-                    \a \b \f \n \r                  \t    \v
-             octal-escape-sequence:
-                     \ octal-digit
-                     \ octal-digit octal-digit
-                     \ octal-digit octal-digit octal-digit
-
-
-
-
-[page 67] (Contents)
-
-           hexadecimal-escape-sequence:
-                 \x hexadecimal-digit
-                 hexadecimal-escape-sequence hexadecimal-digit
-    Description
-2   An integer character constant is a sequence of one or more multibyte characters enclosed
-    in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the
-    letter L, u, or U. With a few exceptions detailed later, the elements of the sequence are
-    any members of the source character set; they are mapped in an implementation-defined
-    manner to members of the execution character set.
-3   The single-quote ', the double-quote ", the question-mark ?, the backslash \, and
-    arbitrary integer values are representable according to the following table of escape
-    sequences:
-          single quote '            \'
-          double quote "            \"
-          question mark ?           \?
-          backslash \               \\
-          octal character           \octal digits
-          hexadecimal character     \x hexadecimal digits
-4   The double-quote " and question-mark ? are representable either by themselves or by the
-    escape sequences \" and \?, respectively, but the single-quote ' and the backslash \
-    shall be represented, respectively, by the escape sequences \' and \\.
-5   The octal digits that follow the backslash in an octal escape sequence are taken to be part
-    of the construction of a single character for an integer character constant or of a single
-    wide character for a wide character constant. The numerical value of the octal integer so
-    formed specifies the value of the desired character or wide character.
-6   The hexadecimal digits that follow the backslash and the letter x in a hexadecimal escape
-    sequence are taken to be part of the construction of a single character for an integer
-    character constant or of a single wide character for a wide character constant. The
-    numerical value of the hexadecimal integer so formed specifies the value of the desired
-    character or wide character.
-7   Each octal or hexadecimal escape sequence is the longest sequence of characters that can
-    constitute the escape sequence.
-8   In addition, characters not in the basic character set are representable by universal
-    character names and certain nongraphic characters are representable by escape sequences
-    consisting of the backslash \ followed by a lowercase letter: \a, \b, \f, \n, \r, \t,
-    and \v.76)
-
-
-
-[page 68] (Contents)
-
-     Constraints
-9    The value of an octal or hexadecimal escape sequence shall be in the range of
-     representable values for the corresponding type:
-            Prefix      Corresponding Type
-            none       unsigned char
-            L          the unsigned type corresponding to wchar_t
-            u          char16_t
-            U          char32_t
-     Semantics
-10   An integer character constant has type int. The value of an integer character constant
-     containing a single character that maps to a single-byte execution character is the
-     numerical value of the representation of the mapped character interpreted as an integer.
-     The value of an integer character constant containing more than one character (e.g.,
-     'ab'), or containing a character or escape sequence that does not map to a single-byte
-     execution character, is implementation-defined. If an integer character constant contains
-     a single character or escape sequence, its value is the one that results when an object with
-     type char whose value is that of the single character or escape sequence is converted to
-     type int.
-11   A wide character constant prefixed by the letter L has type wchar_t, an integer type
-     defined in the <stddef.h> header; a wide character constant prefixed by the letter u or
-     U has type char16_t or char32_t, respectively, unsigned integer types defined in the
-     <uchar.h> header. The value of a wide character constant containing a single
-     multibyte character that maps to a single member of the extended execution character set
-     is the wide character corresponding to that multibyte character, as defined by the
-     mbtowc, mbrtoc16, or mbrtoc32 function as appropriate for its type, with an
-     implementation-defined current locale. The value of a wide character constant containing
-     more than one multibyte character or a single multibyte character that maps to multiple
-     members of the extended execution character set, or containing a multibyte character or
-     escape sequence not represented in the extended execution character set, is
-     implementation-defined.
-12   EXAMPLE 1      The construction '\0' is commonly used to represent the null character.
-
-13   EXAMPLE 2 Consider implementations that use two's-complement representation for integers and eight
-     bits for objects that have type char. In an implementation in which type char has the same range of
-     values as signed char, the integer character constant '\xFF' has the value -1; if type char has the
-     same range of values as unsigned char, the character constant '\xFF' has the value +255.
-
-
-
-
-     76) The semantics of these characters were discussed in 5.2.2. If any other character follows a backslash,
-         the result is not a token and a diagnostic is required. See ''future language directions'' (6.11.4).
-
-[page 69] (Contents)
-
-14   EXAMPLE 3 Even if eight bits are used for objects that have type char, the construction '\x123'
-     specifies an integer character constant containing only one character, since a hexadecimal escape sequence
-     is terminated only by a non-hexadecimal character. To specify an integer character constant containing the
-     two characters whose values are '\x12' and '3', the construction '\0223' may be used, since an octal
-     escape sequence is terminated after three octal digits. (The value of this two-character integer character
-     constant is implementation-defined.)
-
-15   EXAMPLE 4 Even if 12 or more bits are used for objects that have type wchar_t, the construction
-     L'\1234' specifies the implementation-defined value that results from the combination of the values
-     0123 and '4'.
-
-     Forward references: common definitions <stddef.h> (7.19), the mbtowc function
-     (7.22.7.2), Unicode utilities <uchar.h> (7.27).
-     6.4.5 String literals
-     Syntax
-1             string-literal:
-                      encoding-prefixopt " s-char-sequenceopt "
-              encoding-prefix:
-                     u8
-                     u
-                     U
-                     L
-              s-char-sequence:
-                     s-char
-                     s-char-sequence s-char
-              s-char:
-                        any member of the source character set except
-                                     the double-quote ", backslash \, or new-line character
-                        escape-sequence
-     Constraints
-2    A sequence of adjacent string literal tokens shall not include both a wide string literal and
-     a UTF-8 string literal.
-     Description
-3    A character string literal is a sequence of zero or more multibyte characters enclosed in
-     double-quotes, as in "xyz". A UTF-8 string literal is the same, except prefixed by u8.
-     A wide string literal is the same, except prefixed by the letter L, u, or U.
-4    The same considerations apply to each element of the sequence in a string literal as if it
-     were in an integer character constant (for a character or UTF-8 string literal) or a wide
-     character constant (for a wide string literal), except that the single-quote ' is
-     representable either by itself or by the escape sequence \', but the double-quote " shall
-[page 70] (Contents)
-
-    be represented by the escape sequence \".
-    Semantics
-5   In translation phase 6, the multibyte character sequences specified by any sequence of
-    adjacent character and identically-prefixed string literal tokens are concatenated into a
-    single multibyte character sequence. If any of the tokens has an encoding prefix, the
-    resulting multibyte character sequence is treated as having the same prefix; otherwise, it
-    is treated as a character string literal. Whether differently-prefixed wide string literal
-    tokens can be concatenated and, if so, the treatment of the resulting multibyte character
-    sequence are implementation-defined.
-6   In translation phase 7, a byte or code of value zero is appended to each multibyte
-    character sequence that results from a string literal or literals.77) The multibyte character
-    sequence is then used to initialize an array of static storage duration and length just
-    sufficient to contain the sequence. For character string literals, the array elements have
-    type char, and are initialized with the individual bytes of the multibyte character
-    sequence. For UTF-8 string literals, the array elements have type char, and are
-    initialized with the characters of the multibyte character sequence, as encoded in UTF-8.
-    For wide string literals prefixed by the letter L, the array elements have type wchar_t
-    and are initialized with the sequence of wide characters corresponding to the multibyte
-    character sequence, as defined by the mbstowcs function with an implementation-
-    defined current locale. For wide string literals prefixed by the letter u or U, the array
-    elements have type char16_t or char32_t, respectively, and are initialized with the
-    sequence of wide characters corresponding to the multibyte character sequence, as
-    defined by successive calls to the mbrtoc16, or mbrtoc32 function as appropriate for
-    its type, with an implementation-defined current locale. The value of a string literal
-    containing a multibyte character or escape sequence not represented in the execution
-    character set is implementation-defined.
-7   It is unspecified whether these arrays are distinct provided their elements have the
-    appropriate values. If the program attempts to modify such an array, the behavior is
-    undefined.
-8   EXAMPLE 1      This pair of adjacent character string literals
-             "\x12" "3"
-    produces a single character string literal containing the two characters whose values are '\x12' and '3',
-    because escape sequences are converted into single members of the execution character set just prior to
-    adjacent string literal concatenation.
-
-9   EXAMPLE 2      Each of the sequences of adjacent string literal tokens
-
-
-
-    77) A string literal need not be a string (see 7.1.1), because a null character may be embedded in it by a
-        \0 escape sequence.
-
-[page 71] (Contents)
-
-             "a" "b" L"c"
-             "a" L"b" "c"
-             L"a" "b" L"c"
-             L"a" L"b" L"c"
-    is equivalent to the string literal
-             L"abc"
-    Likewise, each of the sequences
-             "a" "b" u"c"
-             "a" u"b" "c"
-             u"a" "b" u"c"
-             u"a" u"b" u"c"
-    is equivalent to
-             u"abc"
-
-    Forward references: common definitions <stddef.h> (7.19), the mbstowcs
-    function (7.22.8.1), Unicode utilities <uchar.h> (7.27).
-    6.4.6 Punctuators
-    Syntax
-1            punctuator: one of
-                    [ ] ( ) { } . ->
-                    ++ -- & * + - ~ !
-                    / % << >> < > <= >=                              ==    !=      ^    |   &&   ||
-                    ? : ; ...
-                    = *= /= %= += -= <<=                             >>=      &=       ^=   |=
-                    , # ##
-                    <: :> <% %> %: %:%:
-    Semantics
-2   A punctuator is a symbol that has independent syntactic and semantic significance.
-    Depending on context, it may specify an operation to be performed (which in turn may
-    yield a value or a function designator, produce a side effect, or some combination thereof)
-    in which case it is known as an operator (other forms of operator also exist in some
-    contexts). An operand is an entity on which an operator acts.
-
-
-
-
-[page 72] (Contents)
-
-3   In all aspects of the language, the six tokens78)
-             <:    :>      <%    %>     %:     %:%:
-    behave, respectively, the same as the six tokens
-             [     ]       {     }      #      ##
-    except for their spelling.79)
-    Forward references: expressions (6.5), declarations (6.7), preprocessing directives
-    (6.10), statements (6.8).
-    6.4.7 Header names
-    Syntax
-1            header-name:
-                    < h-char-sequence >
-                    " q-char-sequence "
-             h-char-sequence:
-                    h-char
-                    h-char-sequence h-char
-             h-char:
-                       any member of the source character set except
-                                    the new-line character and >
-             q-char-sequence:
-                    q-char
-                    q-char-sequence q-char
-             q-char:
-                       any member of the source character set except
-                                    the new-line character and "
-    Semantics
-2   The sequences in both forms of header names are mapped in an implementation-defined
-    manner to headers or external source file names as specified in 6.10.2.
-3   If the characters ', \, ", //, or /* occur in the sequence between the < and > delimiters,
-    the behavior is undefined. Similarly, if the characters ', \, //, or /* occur in the
-
-
-
-
-    78) These tokens are sometimes called ''digraphs''.
-    79) Thus [ and <: behave differently when ''stringized'' (see 6.10.3.2), but can otherwise be freely
-        interchanged.
-
-[page 73] (Contents)
-
-    sequence between the " delimiters, the behavior is undefined.80) Header name
-    preprocessing tokens are recognized only within #include preprocessing directives and
-    in implementation-defined locations within #pragma directives.81)
-4   EXAMPLE       The following sequence of characters:
-             0x3<1/a.h>1e2
-             #include <1/a.h>
-             #define const.member@$
-    forms the following sequence of preprocessing tokens (with each individual preprocessing token delimited
-    by a { on the left and a } on the right).
-             {0x3}{<}{1}{/}{a}{.}{h}{>}{1e2}
-             {#}{include} {<1/a.h>}
-             {#}{define} {const}{.}{member}{@}{$}
-
-    Forward references: source file inclusion (6.10.2).
-    6.4.8 Preprocessing numbers
-    Syntax
-1            pp-number:
-                   digit
-                   . digit
-                   pp-number       digit
-                   pp-number       identifier-nondigit
-                   pp-number       e sign
-                   pp-number       E sign
-                   pp-number       p sign
-                   pp-number       P sign
-                   pp-number       .
-    Description
-2   A preprocessing number begins with a digit optionally preceded by a period (.) and may
-    be followed by valid identifier characters and the character sequences e+, e-, E+, E-,
-    p+, p-, P+, or P-.
-3   Preprocessing number tokens lexically include all floating and integer constant tokens.
-    Semantics
-4   A preprocessing number does not have type or a value; it acquires both after a successful
-    conversion (as part of translation phase 7) to a floating constant token or an integer
-    constant token.
-
-
-    80) Thus, sequences of characters that resemble escape sequences cause undefined behavior.
-    81) For an example of a header name preprocessing token used in a #pragma directive, see 6.10.9.
-
-[page 74] (Contents)
-
-    6.4.9 Comments
-1   Except within a character constant, a string literal, or a comment, the characters /*
-    introduce a comment. The contents of such a comment are examined only to identify
-    multibyte characters and to find the characters */ that terminate it.82)
-2   Except within a character constant, a string literal, or a comment, the characters //
-    introduce a comment that includes all multibyte characters up to, but not including, the
-    next new-line character. The contents of such a comment are examined only to identify
-    multibyte characters and to find the terminating new-line character.
-3   EXAMPLE
-             "a//b"                             //   four-character string literal
-             #include "//e"                     //   undefined behavior
-             // */                              //   comment, not syntax error
-             f = g/**//h;                       //   equivalent to f = g / h;
-             //\
-             i();                               // part of a two-line comment
-             /\
-             / j();                             // part of a two-line comment
-             #define glue(x,y) x##y
-             glue(/,/) k();                     // syntax error, not comment
-             /*//*/ l();                        // equivalent to l();
-             m = n//**/o
-                + p;                            // equivalent to m = n + p;
-
-
-
-
-    82) Thus, /* ... */ comments do not nest.
-
-[page 75] (Contents)
-
-    6.5 Expressions
-1   An expression is a sequence of operators and operands that specifies computation of a
-    value, or that designates an object or a function, or that generates side effects, or that
-    performs a combination thereof. The value computations of the operands of an operator
-    are sequenced before the value computation of the result of the operator.
-2   If a side effect on a scalar object is unsequenced relative to either a different side effect
-    on the same scalar object or a value computation using the value of the same scalar
-    object, the behavior is undefined. If there are multiple allowable orderings of the
-    subexpressions of an expression, the behavior is undefined if such an unsequenced side
-    effect occurs in any of the orderings.83)
-3   The grouping of operators and operands is indicated by the syntax.84) Except as specified
-    later, side effects and value computations of subexpressions are unsequenced.85)
-4   Some operators (the unary operator ~, and the binary operators <<, >>, &, ^, and |,
-    collectively described as bitwise operators) are required to have operands that have
-    integer type. These operators yield values that depend on the internal representations of
-    integers, and have implementation-defined and undefined aspects for signed types.
-5   If an exceptional condition occurs during the evaluation of an expression (that is, if the
-    result is not mathematically defined or not in the range of representable values for its
-    type), the behavior is undefined.
-
-
-
-    83) This paragraph renders undefined statement expressions such as
-                  i = ++i + 1;
-                  a[i++] = i;
-         while allowing
-                  i = i + 1;
-                  a[i] = i;
-
-    84) The syntax specifies the precedence of operators in the evaluation of an expression, which is the same
-        as the order of the major subclauses of this subclause, highest precedence first. Thus, for example, the
-        expressions allowed as the operands of the binary + operator (6.5.6) are those expressions defined in
-        6.5.1 through 6.5.6. The exceptions are cast expressions (6.5.4) as operands of unary operators
-        (6.5.3), and an operand contained between any of the following pairs of operators: grouping
-        parentheses () (6.5.1), subscripting brackets [] (6.5.2.1), function-call parentheses () (6.5.2.2), and
-        the conditional operator ? : (6.5.15).
-         Within each major subclause, the operators have the same precedence. Left- or right-associativity is
-         indicated in each subclause by the syntax for the expressions discussed therein.
-    85) In an expression that is evaluated more than once during the execution of a program, unsequenced and
-        indeterminately sequenced evaluations of its subexpressions need not be performed consistently in
-        different evaluations.
-
-[page 76] (Contents)
-
-6   The effective type of an object for an access to its stored value is the declared type of the
-    object, if any.86) If a value is stored into an object having no declared type through an
-    lvalue having a type that is not a character type, then the type of the lvalue becomes the
-    effective type of the object for that access and for subsequent accesses that do not modify
-    the stored value. If a value is copied into an object having no declared type using
-    memcpy or memmove, or is copied as an array of character type, then the effective type
-    of the modified object for that access and for subsequent accesses that do not modify the
-    value is the effective type of the object from which the value is copied, if it has one. For
-    all other accesses to an object having no declared type, the effective type of the object is
-    simply the type of the lvalue used for the access.
-7   An object shall have its stored value accessed only by an lvalue expression that has one of
-    the following types:87)
-    -- a type compatible with the effective type of the object,
-    -- a qualified version of a type compatible with the effective type of the object,
-    -- a type that is the signed or unsigned type corresponding to the effective type of the
-      object,
-    -- a type that is the signed or unsigned type corresponding to a qualified version of the
-      effective type of the object,
-    -- an aggregate or union type that includes one of the aforementioned types among its
-      members (including, recursively, a member of a subaggregate or contained union), or
-    -- a character type.
-8   A floating expression may be contracted, that is, evaluated as though it were a single
-    operation, thereby omitting rounding errors implied by the source code and the
-    expression evaluation method.88) The FP_CONTRACT pragma in <math.h> provides a
-    way to disallow contracted expressions. Otherwise, whether and how expressions are
-    contracted is implementation-defined.89)
-    Forward references: the FP_CONTRACT pragma (7.12.2), copying functions (7.23.2).
-
-
-    86) Allocated objects have no declared type.
-    87) The intent of this list is to specify those circumstances in which an object may or may not be aliased.
-    88) The intermediate operations in the contracted expression are evaluated as if to infinite precision and
-        range, while the final operation is rounded to the format determined by the expression evaluation
-        method. A contracted expression might also omit the raising of floating-point exceptions.
-    89) This license is specifically intended to allow implementations to exploit fast machine instructions that
-        combine multiple C operators. As contractions potentially undermine predictability, and can even
-        decrease accuracy for containing expressions, their use needs to be well-defined and clearly
-        documented.
-
-[page 77] (Contents)
-
-    6.5.1 Primary expressions
-    Syntax
-1            primary-expression:
-                    identifier
-                    constant
-                    string-literal
-                    ( expression )
-                    generic-selection
-    Semantics
-2   An identifier is a primary expression, provided it has been declared as designating an
-    object (in which case it is an lvalue) or a function (in which case it is a function
-    designator).90)
-3   A constant is a primary expression. Its type depends on its form and value, as detailed in
-    6.4.4.
-4   A string literal is a primary expression. It is an lvalue with type as detailed in 6.4.5.
-5   A parenthesized expression is a primary expression. Its type and value are identical to
-    those of the unparenthesized expression. It is an lvalue, a function designator, or a void
-    expression if the unparenthesized expression is, respectively, an lvalue, a function
-    designator, or a void expression.
-    Forward references: declarations (6.7).
-    6.5.1.1 Generic selection
-    Syntax
-1            generic-selection:
-                    _Generic ( assignment-expression , generic-assoc-list )
-             generic-assoc-list:
-                    generic-association
-                    generic-assoc-list , generic-association
-             generic-association:
-                    type-name : assignment-expression
-                    default : assignment-expression
-    Constraints
-2   A generic selection shall have no more than one default generic association. The type
-    name in a generic association shall specify a complete object type other than a variably
-
-    90) Thus, an undeclared identifier is a violation of the syntax.
-
-[page 78] (Contents)
-
-    modified type. No two generic associations in the same generic selection shall specify
-    compatible types. The controlling expression of a generic selection shall have type
-    compatible with at most one of the types named in its generic association list. If a
-    generic selection has no default generic association, its controlling expression shall
-    have type compatible with exactly one of the types named in its generic association list.
-    Semantics
-3   The controlling expression of a generic selection is not evaluated. If a generic selection
-    has a generic association with a type name that is compatible with the type of the
-    controlling expression, then the result expression of the generic selection is the
-    expression in that generic association. Otherwise, the result expression of the generic
-    selection is the expression in the default generic association. None of the expressions
-    from any other generic association of the generic selection is evaluated.
-4   The type and value of a generic selection are identical to those of its result expression. It
-    is an lvalue, a function designator, or a void expression if its result expression is,
-    respectively, an lvalue, a function designator, or a void expression.
-5   EXAMPLE      The cbrt type-generic macro could be implemented as follows:
-             #define cbrt(X) _Generic((X),                                      \
-                                     long double: cbrtl,                        \
-                                     default: cbrt,                             \
-                                     float: cbrtf                               \
-                                     )(X)
-
-    6.5.2 Postfix operators
-    Syntax
-1            postfix-expression:
-                    primary-expression
-                    postfix-expression [ expression ]
-                    postfix-expression ( argument-expression-listopt )
-                    postfix-expression . identifier
-                    postfix-expression -> identifier
-                    postfix-expression ++
-                    postfix-expression --
-                    ( type-name ) { initializer-list }
-                    ( type-name ) { initializer-list , }
-             argument-expression-list:
-                   assignment-expression
-                   argument-expression-list , assignment-expression
-
-
-
-
-[page 79] (Contents)
-
-    6.5.2.1 Array subscripting
-    Constraints
-1   One of the expressions shall have type ''pointer to complete object type'', the other
-    expression shall have integer type, and the result has type ''type''.
-    Semantics
-2   A postfix expression followed by an expression in square brackets [] is a subscripted
-    designation of an element of an array object. The definition of the subscript operator []
-    is that E1[E2] is identical to (*((E1)+(E2))). Because of the conversion rules that
-    apply to the binary + operator, if E1 is an array object (equivalently, a pointer to the
-    initial element of an array object) and E2 is an integer, E1[E2] designates the E2-th
-    element of E1 (counting from zero).
-3   Successive subscript operators designate an element of a multidimensional array object.
-    If E is an n-dimensional array (n >= 2) with dimensions i x j x . . . x k, then E (used as
-    other than an lvalue) is converted to a pointer to an (n - 1)-dimensional array with
-    dimensions j x . . . x k. If the unary * operator is applied to this pointer explicitly, or
-    implicitly as a result of subscripting, the result is the referenced (n - 1)-dimensional
-    array, which itself is converted into a pointer if used as other than an lvalue. It follows
-    from this that arrays are stored in row-major order (last subscript varies fastest).
-4   EXAMPLE        Consider the array object defined by the declaration
-             int x[3][5];
-    Here x is a 3 x 5 array of ints; more precisely, x is an array of three element objects, each of which is an
-    array of five ints. In the expression x[i], which is equivalent to (*((x)+(i))), x is first converted to
-    a pointer to the initial array of five ints. Then i is adjusted according to the type of x, which conceptually
-    entails multiplying i by the size of the object to which the pointer points, namely an array of five int
-    objects. The results are added and indirection is applied to yield an array of five ints. When used in the
-    expression x[i][j], that array is in turn converted to a pointer to the first of the ints, so x[i][j]
-    yields an int.
-
-    Forward references: additive operators (6.5.6), address and indirection operators
-    (6.5.3.2), array declarators (6.7.6.2).
-    6.5.2.2 Function calls
-    Constraints
-1   The expression that denotes the called function91) shall have type pointer to function
-    returning void or returning a complete object type other than an array type.
-2   If the expression that denotes the called function has a type that includes a prototype, the
-    number of arguments shall agree with the number of parameters. Each argument shall
-
-
-    91) Most often, this is the result of converting an identifier that is a function designator.
-
-[page 80] (Contents)
-
-    have a type such that its value may be assigned to an object with the unqualified version
-    of the type of its corresponding parameter.
-    Semantics
-3   A postfix expression followed by parentheses () containing a possibly empty, comma-
-    separated list of expressions is a function call. The postfix expression denotes the called
-    function. The list of expressions specifies the arguments to the function.
-4   An argument may be an expression of any complete object type. In preparing for the call
-    to a function, the arguments are evaluated, and each parameter is assigned the value of the
-    corresponding argument.92)
-5   If the expression that denotes the called function has type pointer to function returning an
-    object type, the function call expression has the same type as that object type, and has the
-    value determined as specified in 6.8.6.4. Otherwise, the function call has type void.
-6   If the expression that denotes the called function has a type that does not include a
-    prototype, the integer promotions are performed on each argument, and arguments that
-    have type float are promoted to double. These are called the default argument
-    promotions. If the number of arguments does not equal the number of parameters, the
-    behavior is undefined. If the function is defined with a type that includes a prototype, and
-    either the prototype ends with an ellipsis (, ...) or the types of the arguments after
-    promotion are not compatible with the types of the parameters, the behavior is undefined.
-    If the function is defined with a type that does not include a prototype, and the types of
-    the arguments after promotion are not compatible with those of the parameters after
-    promotion, the behavior is undefined, except for the following cases:
-    -- one promoted type is a signed integer type, the other promoted type is the
-      corresponding unsigned integer type, and the value is representable in both types;
-    -- both types are pointers to qualified or unqualified versions of a character type or
-      void.
-7   If the expression that denotes the called function has a type that does include a prototype,
-    the arguments are implicitly converted, as if by assignment, to the types of the
-    corresponding parameters, taking the type of each parameter to be the unqualified version
-    of its declared type. The ellipsis notation in a function prototype declarator causes
-    argument type conversion to stop after the last declared parameter. The default argument
-    promotions are performed on trailing arguments.
-
-
-
-    92) A function may change the values of its parameters, but these changes cannot affect the values of the
-        arguments. On the other hand, it is possible to pass a pointer to an object, and the function may
-        change the value of the object pointed to. A parameter declared to have array or function type is
-        adjusted to have a pointer type as described in 6.9.1.
-
-[page 81] (Contents)
-
-8    No other conversions are performed implicitly; in particular, the number and types of
-     arguments are not compared with those of the parameters in a function definition that
-     does not include a function prototype declarator.
-9    If the function is defined with a type that is not compatible with the type (of the
-     expression) pointed to by the expression that denotes the called function, the behavior is
-     undefined.
-10   There is a sequence point after the evaluations of the function designator and the actual
-     arguments but before the actual call. Every evaluation in the calling function (including
-     other function calls) that is not otherwise specifically sequenced before or after the
-     execution of the body of the called function is indeterminately sequenced with respect to
-     the execution of the called function.93)
-11   Recursive function calls shall be permitted, both directly and indirectly through any chain
-     of other functions.
-12   EXAMPLE        In the function call
-              (*pf[f1()]) (f2(), f3() + f4())
-     the functions f1, f2, f3, and f4 may be called in any order. All side effects have to be completed before
-     the function pointed to by pf[f1()] is called.
-
-     Forward references: function declarators (including prototypes) (6.7.6.3), function
-     definitions (6.9.1), the return statement (6.8.6.4), simple assignment (6.5.16.1).
-     6.5.2.3 Structure and union members
-     Constraints
-1    The first operand of the . operator shall have a qualified or unqualified structure or union
-     type, and the second operand shall name a member of that type.
-2    The first operand of the -> operator shall have type ''pointer to qualified or unqualified
-     structure'' or ''pointer to qualified or unqualified union'', and the second operand shall
-     name a member of the type pointed to.
-     Semantics
-3    A postfix expression followed by the . operator and an identifier designates a member of
-     a structure or union object. The value is that of the named member,94) and is an lvalue if
-     the first expression is an lvalue. If the first expression has qualified type, the result has
-     the so-qualified version of the type of the designated member.
-
-     93) In other words, function executions do not ''interleave'' with each other.
-     94) If the member used to access the contents of a union object is not the same as the member last used to
-         store a value in the object, the appropriate part of the object representation of the value is reinterpreted
-         as an object representation in the new type as described in 6.2.6 (a process sometimes called ''type
-         punning''). This might be a trap representation.
-
-[page 82] (Contents)
-
-4   A postfix expression followed by the -> operator and an identifier designates a member
-    of a structure or union object. The value is that of the named member of the object to
-    which the first expression points, and is an lvalue.95) If the first expression is a pointer to
-    a qualified type, the result has the so-qualified version of the type of the designated
-    member.
-5   Accessing a member of an _Atomic-qualified structure or union object results in
-    undefined behavior.96)
-6   One special guarantee is made in order to simplify the use of unions: if a union contains
-    several structures that share a common initial sequence (see below), and if the union
-    object currently contains one of these structures, it is permitted to inspect the common
-    initial part of any of them anywhere that a declaration of the completed type of the union
-    is visible. Two structures share a common initial sequence if corresponding members
-    have compatible types (and, for bit-fields, the same widths) for a sequence of one or more
-    initial members.
-7   EXAMPLE 1 If f is a function returning a structure or union, and x is a member of that structure or
-    union, f().x is a valid postfix expression but is not an lvalue.
-
-8   EXAMPLE 2       In:
-             struct s { int i; const int ci; };
-             struct s s;
-             const struct s cs;
-             volatile struct s vs;
-    the various members have the types:
-             s.i          int
-             s.ci         const int
-             cs.i         const int
-             cs.ci        const int
-             vs.i         volatile int
-             vs.ci        volatile const int
-
-
-
-
-    95) If &E is a valid pointer expression (where & is the ''address-of '' operator, which generates a pointer to
-        its operand), the expression (&E)->MOS is the same as E.MOS.
-    96) A data race would occur if access to the entire structure or union in one thread conflicts with access to
-        a member from another thread, where at least one access is a modification. Such a data race results in
-        undefined behavior.
-
-[page 83] (Contents)
-
-9   EXAMPLE 3       The following is a valid fragment:
-             union {
-                     struct {
-                           int      alltypes;
-                     } n;
-                     struct {
-                           int      type;
-                           int      intnode;
-                     } ni;
-                     struct {
-                           int      type;
-                           double doublenode;
-                     } nf;
-             } u;
-             u.nf.type = 1;
-             u.nf.doublenode = 3.14;
-             /* ... */
-             if (u.n.alltypes == 1)
-                     if (sin(u.nf.doublenode) == 0.0)
-                           /* ... */
-    The following is not a valid fragment (because the union type is not visible within function f):
-             struct t1 { int m; };
-             struct t2 { int m; };
-             int f(struct t1 *p1, struct t2 *p2)
-             {
-                   if (p1->m < 0)
-                           p2->m = -p2->m;
-                   return p1->m;
-             }
-             int g()
-             {
-                   union {
-                           struct t1 s1;
-                           struct t2 s2;
-                   } u;
-                   /* ... */
-                   return f(&u.s1, &u.s2);
-             }
-
-    Forward references: address and indirection operators (6.5.3.2), structure and union
-    specifiers (6.7.2.1).
-
-
-
-
-[page 84] (Contents)
-
-    6.5.2.4 Postfix increment and decrement operators
-    Constraints
-1   The operand of the postfix increment or decrement operator shall have qualified or
-    unqualified real or pointer type and shall be a modifiable lvalue.
-    Semantics
-2   The result of the postfix ++ operator is the value of the operand. As a side effect, the
-    value of the operand object is incremented (that is, the value 1 of the appropriate type is
-    added to it). See the discussions of additive operators and compound assignment for
-    information on constraints, types, and conversions and the effects of operations on
-    pointers. The value computation of the result is sequenced before the side effect of
-    updating the stored value of the operand. With respect to an indeterminately-sequenced
-    function call, the operation of postfix ++ is a single evaluation. Postfix ++ on an object
-    with     _Atomic-qualified       type   is    a    read-modify-write      operation    with
-                                                             97)
-    memory_order_seq_cst memory order semantics.
-3   The postfix -- operator is analogous to the postfix ++ operator, except that the value of
-    the operand is decremented (that is, the value 1 of the appropriate type is subtracted from
-    it).
-    Forward references: additive operators (6.5.6), compound assignment (6.5.16.2).
-    6.5.2.5 Compound literals
-    Constraints
-1   The type name shall specify a complete object type or an array of unknown size, but not a
-    variable length array type.
-2   All the constraints for initializer lists in 6.7.9 also apply to compound literals.
-    Semantics
-3   A postfix expression that consists of a parenthesized type name followed by a brace-
-    enclosed list of initializers is a compound literal. It provides an unnamed object whose
-    value is given by the initializer list.98)
-
-
-    97) Where a pointer to an atomic object can be formed, this is equivalent to the following code sequence
-        where T is the type of E:
-                 T tmp;
-                 T result = E;
-                 do {
-                        tmp = result + 1;
-                 } while (!atomic_compare_exchange_strong(&E, &result, tmp));
-         with result being the result of the operation.
-
-[page 85] (Contents)
-
-4    If the type name specifies an array of unknown size, the size is determined by the
-     initializer list as specified in 6.7.9, and the type of the compound literal is that of the
-     completed array type. Otherwise (when the type name specifies an object type), the type
-     of the compound literal is that specified by the type name. In either case, the result is an
-     lvalue.
-5    The value of the compound literal is that of an unnamed object initialized by the
-     initializer list. If the compound literal occurs outside the body of a function, the object
-     has static storage duration; otherwise, it has automatic storage duration associated with
-     the enclosing block.
-6    All the semantic rules for initializer lists in 6.7.9 also apply to compound literals.99)
-7    String literals, and compound literals with const-qualified types, need not designate
-     distinct objects.100)
-8    EXAMPLE 1       The file scope definition
-              int *p = (int []){2, 4};
-     initializes p to point to the first element of an array of two ints, the first having the value two and the
-     second, four. The expressions in this compound literal are required to be constant. The unnamed object
-     has static storage duration.
-
-9    EXAMPLE 2       In contrast, in
-              void f(void)
-              {
-                    int *p;
-                    /*...*/
-                    p = (int [2]){*p};
-                    /*...*/
-              }
-     p is assigned the address of the first element of an array of two ints, the first having the value previously
-     pointed to by p and the second, zero. The expressions in this compound literal need not be constant. The
-     unnamed object has automatic storage duration.
-
-10   EXAMPLE 3 Initializers with designations can be combined with compound literals. Structure objects
-     created using compound literals can be passed to functions without depending on member order:
-              drawline((struct point){.x=1, .y=1},
-                    (struct point){.x=3, .y=4});
-     Or, if drawline instead expected pointers to struct point:
-
-
-
-     98) Note that this differs from a cast expression. For example, a cast specifies a conversion to scalar types
-         or void only, and the result of a cast expression is not an lvalue.
-     99) For example, subobjects without explicit initializers are initialized to zero.
-     100) This allows implementations to share storage for string literals and constant compound literals with
-          the same or overlapping representations.
-
-[page 86] (Contents)
-
-              drawline(&(struct point){.x=1, .y=1},
-                    &(struct point){.x=3, .y=4});
-
-11   EXAMPLE 4        A read-only compound literal can be specified through constructions like:
-              (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}
-
-12   EXAMPLE 5        The following three expressions have different meanings:
-              "/tmp/fileXXXXXX"
-              (char []){"/tmp/fileXXXXXX"}
-              (const char []){"/tmp/fileXXXXXX"}
-     The first always has static storage duration and has type array of char, but need not be modifiable; the last
-     two have automatic storage duration when they occur within the body of a function, and the first of these
-     two is modifiable.
-
-13   EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory
-     and can even be shared. For example,
-              (const char []){"abc"} == "abc"
-     might yield 1 if the literals' storage is shared.
-
-14   EXAMPLE 7 Since compound literals are unnamed, a single compound literal cannot specify a circularly
-     linked object. For example, there is no way to write a self-referential compound literal that could be used
-     as the function argument in place of the named object endless_zeros below:
-              struct int_list { int car; struct int_list *cdr; };
-              struct int_list endless_zeros = {0, &endless_zeros};
-              eval(endless_zeros);
-
-15   EXAMPLE 8        Each compound literal creates only a single object in a given scope:
-              struct s { int i; };
-              int f (void)
-              {
-                    struct s *p = 0, *q;
-                    int j = 0;
-              again:
-                        q = p, p = &((struct s){ j++ });
-                        if (j < 2) goto again;
-                        return p == q && q->i == 1;
-              }
-     The function f() always returns the value 1.
-16   Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the
-     lifetime of the unnamed object would be the body of the loop only, and on entry next time around p would
-     have an indeterminate value, which would result in undefined behavior.
-
-     Forward references: type names (6.7.7), initialization (6.7.9).
-
-
-
-
-[page 87] (Contents)
-
-    6.5.3 Unary operators
-    Syntax
-1            unary-expression:
-                    postfix-expression
-                    ++ unary-expression
-                    -- unary-expression
-                    unary-operator cast-expression
-                    sizeof unary-expression
-                    sizeof ( type-name )
-                    alignof ( type-name )
-             unary-operator: one of
-                    & * + - ~             !
-    6.5.3.1 Prefix increment and decrement operators
-    Constraints
-1   The operand of the prefix increment or decrement operator shall have qualified or
-    unqualified real or pointer type and shall be a modifiable lvalue.
-    Semantics
-2   The value of the operand of the prefix ++ operator is incremented. The result is the new
-    value of the operand after incrementation. The expression ++E is equivalent to (E+=1).
-    See the discussions of additive operators and compound assignment for information on
-    constraints, types, side effects, and conversions and the effects of operations on pointers.
-3   The prefix -- operator is analogous to the prefix ++ operator, except that the value of the
-    operand is decremented.
-    Forward references: additive operators (6.5.6), compound assignment (6.5.16.2).
-    6.5.3.2 Address and indirection operators
-    Constraints
-1   The operand of the unary & operator shall be either a function designator, the result of a
-    [] or unary * operator, or an lvalue that designates an object that is not a bit-field and is
-    not declared with the register storage-class specifier.
-2   The operand of the unary * operator shall have pointer type.
-    Semantics
-3   The unary & operator yields the address of its operand. If the operand has type ''type'',
-    the result has type ''pointer to type''. If the operand is the result of a unary * operator,
-    neither that operator nor the & operator is evaluated and the result is as if both were
-    omitted, except that the constraints on the operators still apply and the result is not an
-
-[page 88] (Contents)
-
-    lvalue. Similarly, if the operand is the result of a [] operator, neither the & operator nor
-    the unary * that is implied by the [] is evaluated and the result is as if the & operator
-    were removed and the [] operator were changed to a + operator. Otherwise, the result is
-    a pointer to the object or function designated by its operand.
-4   The unary * operator denotes indirection. If the operand points to a function, the result is
-    a function designator; if it points to an object, the result is an lvalue designating the
-    object. If the operand has type ''pointer to type'', the result has type ''type''. If an
-    invalid value has been assigned to the pointer, the behavior of the unary * operator is
-    undefined.101)
-    Forward references: storage-class specifiers (6.7.1), structure and union specifiers
-    (6.7.2.1).
-    6.5.3.3 Unary arithmetic operators
-    Constraints
-1   The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
-    integer type; of the ! operator, scalar type.
-    Semantics
-2   The result of the unary + operator is the value of its (promoted) operand. The integer
-    promotions are performed on the operand, and the result has the promoted type.
-3   The result of the unary - operator is the negative of its (promoted) operand. The integer
-    promotions are performed on the operand, and the result has the promoted type.
-4   The result of the ~ operator is the bitwise complement of its (promoted) operand (that is,
-    each bit in the result is set if and only if the corresponding bit in the converted operand is
-    not set). The integer promotions are performed on the operand, and the result has the
-    promoted type. If the promoted type is an unsigned type, the expression ~E is equivalent
-    to the maximum value representable in that type minus E.
-5   The result of the logical negation operator ! is 0 if the value of its operand compares
-    unequal to 0, 1 if the value of its operand compares equal to 0. The result has type int.
-    The expression !E is equivalent to (0==E).
-
-
-
-    101) Thus, &*E is equivalent to E (even if E is a null pointer), and &(E1[E2]) to ((E1)+(E2)). It is
-         always true that if E is a function designator or an lvalue that is a valid operand of the unary &
-         operator, *&E is a function designator or an lvalue equal to E. If *P is an lvalue and T is the name of
-         an object pointer type, *(T)P is an lvalue that has a type compatible with that to which T points.
-         Among the invalid values for dereferencing a pointer by the unary * operator are a null pointer, an
-         address inappropriately aligned for the type of object pointed to, and the address of an object after the
-         end of its lifetime.
-
-[page 89] (Contents)
-
-    6.5.3.4 The sizeof and alignof operators
-    Constraints
-1   The sizeof operator shall not be applied to an expression that has function type or an
-    incomplete type, to the parenthesized name of such a type, or to an expression that
-    designates a bit-field member. The alignof operator shall not be applied to a function
-    type or an incomplete type.
-    Semantics
-2   The sizeof operator yields the size (in bytes) of its operand, which may be an
-    expression or the parenthesized name of a type. The size is determined from the type of
-    the operand. The result is an integer. If the type of the operand is a variable length array
-    type, the operand is evaluated; otherwise, the operand is not evaluated and the result is an
-    integer constant.
-3   The alignof operator yields the alignment requirement of its operand type. The result
-    is an integer constant. When applied to an array type, the result is the alignment
-    requirement of the element type.
-4   When sizeof is applied to an operand that has type char, unsigned char, or
-    signed char, (or a qualified version thereof) the result is 1. When applied to an
-    operand that has array type, the result is the total number of bytes in the array.102) When
-    applied to an operand that has structure or union type, the result is the total number of
-    bytes in such an object, including internal and trailing padding.
-5   The value of the result of both operators is implementation-defined, and its type (an
-    unsigned integer type) is size_t, defined in <stddef.h> (and other headers).
-6   EXAMPLE 1 A principal use of the sizeof operator is in communication with routines such as storage
-    allocators and I/O systems. A storage-allocation function might accept a size (in bytes) of an object to
-    allocate and return a pointer to void. For example:
-            extern void *alloc(size_t);
-            double *dp = alloc(sizeof *dp);
-    The implementation of the alloc function should ensure that its return value is aligned suitably for
-    conversion to a pointer to double.
-
-7   EXAMPLE 2      Another use of the sizeof operator is to compute the number of elements in an array:
-            sizeof array / sizeof array[0]
-
-8   EXAMPLE 3      In this example, the size of a variable length array is computed and returned from a
-    function:
-            #include <stddef.h>
-
-
-
-    102) When applied to a parameter declared to have array or function type, the sizeof operator yields the
-         size of the adjusted (pointer) type (see 6.9.1).
-
-[page 90] (Contents)
-
-             size_t fsize3(int n)
-             {
-                   char b[n+3];                  // variable length array
-                   return sizeof b;              // execution time sizeof
-             }
-             int main()
-             {
-                   size_t size;
-                   size = fsize3(10); // fsize3 returns 13
-                   return 0;
-             }
-
-    Forward references: common definitions <stddef.h> (7.19), declarations (6.7),
-    structure and union specifiers (6.7.2.1), type names (6.7.7), array declarators (6.7.6.2).
-    6.5.4 Cast operators
-    Syntax
-1            cast-expression:
-                    unary-expression
-                    ( type-name ) cast-expression
-    Constraints
-2   Unless the type name specifies a void type, the type name shall specify qualified or
-    unqualified scalar type and the operand shall have scalar type.
-3   Conversions that involve pointers, other than where permitted by the constraints of
-    6.5.16.1, shall be specified by means of an explicit cast.
-4   A pointer type shall not be converted to any floating type. A floating type shall not be
-    converted to any pointer type.
-    Semantics
-5   Preceding an expression by a parenthesized type name converts the value of the
-    expression to the named type. This construction is called a cast.103) A cast that specifies
-    no conversion has no effect on the type or value of an expression.
-6   If the value of the expression is represented with greater precision or range than required
-    by the type named by the cast (6.3.1.8), then the cast specifies a conversion even if the
-    type of the expression is the same as the named type.
-    Forward references: equality operators (6.5.9), function declarators (including
-    prototypes) (6.7.6.3), simple assignment (6.5.16.1), type names (6.7.7).
-
-
-
-    103) A cast does not yield an lvalue. Thus, a cast to a qualified type has the same effect as a cast to the
-         unqualified version of the type.
-
-[page 91] (Contents)
-
-    6.5.5 Multiplicative operators
-    Syntax
-1            multiplicative-expression:
-                     cast-expression
-                     multiplicative-expression * cast-expression
-                     multiplicative-expression / cast-expression
-                     multiplicative-expression % cast-expression
-    Constraints
-2   Each of the operands shall have arithmetic type. The operands of the % operator shall
-    have integer type.
-    Semantics
-3   The usual arithmetic conversions are performed on the operands.
-4   The result of the binary * operator is the product of the operands.
-5   The result of the / operator is the quotient from the division of the first operand by the
-    second; the result of the % operator is the remainder. In both operations, if the value of
-    the second operand is zero, the behavior is undefined.
-6   When integers are divided, the result of the / operator is the algebraic quotient with any
-    fractional part discarded.104) If the quotient a/b is representable, the expression
-    (a/b)*b + a%b shall equal a; otherwise, the behavior of both a/b and a%b is
-    undefined.
-    6.5.6 Additive operators
-    Syntax
-1            additive-expression:
-                    multiplicative-expression
-                    additive-expression + multiplicative-expression
-                    additive-expression - multiplicative-expression
-    Constraints
-2   For addition, either both operands shall have arithmetic type, or one operand shall be a
-    pointer to a complete object type and the other shall have integer type. (Incrementing is
-    equivalent to adding 1.)
-3   For subtraction, one of the following shall hold:
-
-
-
-
-    104) This is often called ''truncation toward zero''.
-
-[page 92] (Contents)
-
-    -- both operands have arithmetic type;
-    -- both operands are pointers to qualified or unqualified versions of compatible complete
-      object types; or
-    -- the left operand is a pointer to a complete object type and the right operand has
-      integer type.
-    (Decrementing is equivalent to subtracting 1.)
-    Semantics
-4   If both operands have arithmetic type, the usual arithmetic conversions are performed on
-    them.
-5   The result of the binary + operator is the sum of the operands.
-6   The result of the binary - operator is the difference resulting from the subtraction of the
-    second operand from the first.
-7   For the purposes of these operators, a pointer to an object that is not an element of an
-    array behaves the same as a pointer to the first element of an array of length one with the
-    type of the object as its element type.
-8   When an expression that has integer type is added to or subtracted from a pointer, the
-    result has the type of the pointer operand. If the pointer operand points to an element of
-    an array object, and the array is large enough, the result points to an element offset from
-    the original element such that the difference of the subscripts of the resulting and original
-    array elements equals the integer expression. In other words, if the expression P points to
-    the i-th element of an array object, the expressions (P)+N (equivalently, N+(P)) and
-    (P)-N (where N has the value n) point to, respectively, the i+n-th and i-n-th elements of
-    the array object, provided they exist. Moreover, if the expression P points to the last
-    element of an array object, the expression (P)+1 points one past the last element of the
-    array object, and if the expression Q points one past the last element of an array object,
-    the expression (Q)-1 points to the last element of the array object. If both the pointer
-    operand and the result point to elements of the same array object, or one past the last
-    element of the array object, the evaluation shall not produce an overflow; otherwise, the
-    behavior is undefined. If the result points one past the last element of the array object, it
-    shall not be used as the operand of a unary * operator that is evaluated.
-9   When two pointers are subtracted, both shall point to elements of the same array object,
-    or one past the last element of the array object; the result is the difference of the
-    subscripts of the two array elements. The size of the result is implementation-defined,
-    and its type (a signed integer type) is ptrdiff_t defined in the <stddef.h> header.
-    If the result is not representable in an object of that type, the behavior is undefined. In
-    other words, if the expressions P and Q point to, respectively, the i-th and j-th elements of
-    an array object, the expression (P)-(Q) has the value i-j provided the value fits in an
-
-[page 93] (Contents)
-
-     object of type ptrdiff_t. Moreover, if the expression P points either to an element of
-     an array object or one past the last element of an array object, and the expression Q points
-     to the last element of the same array object, the expression ((Q)+1)-(P) has the same
-     value as ((Q)-(P))+1 and as -((P)-((Q)+1)), and has the value zero if the
-     expression P points one past the last element of the array object, even though the
-     expression (Q)+1 does not point to an element of the array object.105)
-10   EXAMPLE        Pointer arithmetic is well defined with pointers to variable length array types.
-              {
-                       int n = 4, m = 3;
-                       int a[n][m];
-                       int (*p)[m] = a;            //   p == &a[0]
-                       p += 1;                     //   p == &a[1]
-                       (*p)[2] = 99;               //   a[1][2] == 99
-                       n = p - a;                  //   n == 1
-              }
-11   If array a in the above example were declared to be an array of known constant size, and pointer p were
-     declared to be a pointer to an array of the same known constant size (pointing to a), the results would be
-     the same.
-
-     Forward references: array declarators (6.7.6.2), common definitions <stddef.h>
-     (7.19).
-     6.5.7 Bitwise shift operators
-     Syntax
-1             shift-expression:
-                      additive-expression
-                      shift-expression << additive-expression
-                      shift-expression >> additive-expression
-     Constraints
-2    Each of the operands shall have integer type.
-     Semantics
-3    The integer promotions are performed on each of the operands. The type of the result is
-     that of the promoted left operand. If the value of the right operand is negative or is
-
-     105) Another way to approach pointer arithmetic is first to convert the pointer(s) to character pointer(s): In
-          this scheme the integer expression added to or subtracted from the converted pointer is first multiplied
-          by the size of the object originally pointed to, and the resulting pointer is converted back to the
-          original type. For pointer subtraction, the result of the difference between the character pointers is
-          similarly divided by the size of the object originally pointed to.
-          When viewed in this way, an implementation need only provide one extra byte (which may overlap
-          another object in the program) just after the end of the object in order to satisfy the ''one past the last
-          element'' requirements.
-
-[page 94] (Contents)
-
-    greater than or equal to the width of the promoted left operand, the behavior is undefined.
-4   The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are filled with
-    zeros. If E1 has an unsigned type, the value of the result is E1 x 2E2 , reduced modulo
-    one more than the maximum value representable in the result type. If E1 has a signed
-    type and nonnegative value, and E1 x 2E2 is representable in the result type, then that is
-    the resulting value; otherwise, the behavior is undefined.
-5   The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an unsigned type
-    or if E1 has a signed type and a nonnegative value, the value of the result is the integral
-    part of the quotient of E1 / 2E2 . If E1 has a signed type and a negative value, the
-    resulting value is implementation-defined.
-    6.5.8 Relational operators
-    Syntax
-1            relational-expression:
-                     shift-expression
-                     relational-expression   <    shift-expression
-                     relational-expression   >    shift-expression
-                     relational-expression   <=   shift-expression
-                     relational-expression   >=   shift-expression
-    Constraints
-2   One of the following shall hold:
-    -- both operands have real type; or
-    -- both operands are pointers to qualified or unqualified versions of compatible object
-      types.
-    Semantics
-3   If both of the operands have arithmetic type, the usual arithmetic conversions are
-    performed.
-4   For the purposes of these operators, a pointer to an object that is not an element of an
-    array behaves the same as a pointer to the first element of an array of length one with the
-    type of the object as its element type.
-5   When two pointers are compared, the result depends on the relative locations in the
-    address space of the objects pointed to. If two pointers to object types both point to the
-    same object, or both point one past the last element of the same array object, they
-    compare equal. If the objects pointed to are members of the same aggregate object,
-    pointers to structure members declared later compare greater than pointers to members
-    declared earlier in the structure, and pointers to array elements with larger subscript
-    values compare greater than pointers to elements of the same array with lower subscript
-
-[page 95] (Contents)
-
-    values. All pointers to members of the same union object compare equal. If the
-    expression P points to an element of an array object and the expression Q points to the
-    last element of the same array object, the pointer expression Q+1 compares greater than
-    P. In all other cases, the behavior is undefined.
-6   Each of the operators < (less than), > (greater than), <= (less than or equal to), and >=
-    (greater than or equal to) shall yield 1 if the specified relation is true and 0 if it is
-    false.106) The result has type int.
-    6.5.9 Equality operators
-    Syntax
-1            equality-expression:
-                    relational-expression
-                    equality-expression == relational-expression
-                    equality-expression != relational-expression
-    Constraints
-2   One of the following shall hold:
-    -- both operands have arithmetic type;
-    -- both operands are pointers to qualified or unqualified versions of compatible types;
-    -- one operand is a pointer to an object type and the other is a pointer to a qualified or
-      unqualified version of void; or
-    -- one operand is a pointer and the other is a null pointer constant.
-    Semantics
-3   The == (equal to) and != (not equal to) operators are analogous to the relational
-    operators except for their lower precedence.107) Each of the operators yields 1 if the
-    specified relation is true and 0 if it is false. The result has type int. For any pair of
-    operands, exactly one of the relations is true.
-4   If both of the operands have arithmetic type, the usual arithmetic conversions are
-    performed. Values of complex types are equal if and only if both their real parts are equal
-    and also their imaginary parts are equal. Any two values of arithmetic types from
-    different type domains are equal if and only if the results of their conversions to the
-    (complex) result type determined by the usual arithmetic conversions are equal.
-
-
-
-    106) The expression a<b<c is not interpreted as in ordinary mathematics. As the syntax indicates, it
-         means (a<b)<c; in other words, ''if a is less than b, compare 1 to c; otherwise, compare 0 to c''.
-    107) Because of the precedences, a<b == c<d is 1 whenever a<b and c<d have the same truth-value.
-
-[page 96] (Contents)
-
-5   Otherwise, at least one operand is a pointer. If one operand is a pointer and the other is a
-    null pointer constant, the null pointer constant is converted to the type of the pointer. If
-    one operand is a pointer to an object type and the other is a pointer to a qualified or
-    unqualified version of void, the former is converted to the type of the latter.
-6   Two pointers compare equal if and only if both are null pointers, both are pointers to the
-    same object (including a pointer to an object and a subobject at its beginning) or function,
-    both are pointers to one past the last element of the same array object, or one is a pointer
-    to one past the end of one array object and the other is a pointer to the start of a different
-    array object that happens to immediately follow the first array object in the address
-    space.108)
-7   For the purposes of these operators, a pointer to an object that is not an element of an
-    array behaves the same as a pointer to the first element of an array of length one with the
-    type of the object as its element type.
-    6.5.10 Bitwise AND operator
-    Syntax
-1            AND-expression:
-                   equality-expression
-                   AND-expression & equality-expression
-    Constraints
-2   Each of the operands shall have integer type.
-    Semantics
-3   The usual arithmetic conversions are performed on the operands.
-4   The result of the binary & operator is the bitwise AND of the operands (that is, each bit in
-    the result is set if and only if each of the corresponding bits in the converted operands is
-    set).
-
-
-
-
-    108) Two objects may be adjacent in memory because they are adjacent elements of a larger array or
-         adjacent members of a structure with no padding between them, or because the implementation chose
-         to place them so, even though they are unrelated. If prior invalid pointer operations (such as accesses
-         outside array bounds) produced undefined behavior, subsequent comparisons also produce undefined
-         behavior.
-
-[page 97] (Contents)
-
-    6.5.11 Bitwise exclusive OR operator
-    Syntax
-1            exclusive-OR-expression:
-                     AND-expression
-                     exclusive-OR-expression ^ AND-expression
-    Constraints
-2   Each of the operands shall have integer type.
-    Semantics
-3   The usual arithmetic conversions are performed on the operands.
-4   The result of the ^ operator is the bitwise exclusive OR of the operands (that is, each bit
-    in the result is set if and only if exactly one of the corresponding bits in the converted
-    operands is set).
-    6.5.12 Bitwise inclusive OR operator
-    Syntax
-1            inclusive-OR-expression:
-                     exclusive-OR-expression
-                     inclusive-OR-expression | exclusive-OR-expression
-    Constraints
-2   Each of the operands shall have integer type.
-    Semantics
-3   The usual arithmetic conversions are performed on the operands.
-4   The result of the | operator is the bitwise inclusive OR of the operands (that is, each bit in
-    the result is set if and only if at least one of the corresponding bits in the converted
-    operands is set).
-
-
-
-
-[page 98] (Contents)
-
-    6.5.13 Logical AND operator
-    Syntax
-1             logical-AND-expression:
-                      inclusive-OR-expression
-                      logical-AND-expression && inclusive-OR-expression
-    Constraints
-2   Each of the operands shall have scalar type.
-    Semantics
-3   The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it
-    yields 0. The result has type int.
-4   Unlike the bitwise binary & operator, the && operator guarantees left-to-right evaluation;
-    if the second operand is evaluated, there is a sequence point between the evaluations of
-    the first and second operands. If the first operand compares equal to 0, the second
-    operand is not evaluated.
-    6.5.14 Logical OR operator
-    Syntax
-1             logical-OR-expression:
-                      logical-AND-expression
-                      logical-OR-expression || logical-AND-expression
-    Constraints
-2   Each of the operands shall have scalar type.
-    Semantics
-3   The || operator shall yield 1 if either of its operands compare unequal to 0; otherwise, it
-    yields 0. The result has type int.
-4   Unlike the bitwise | operator, the || operator guarantees left-to-right evaluation; if the
-    second operand is evaluated, there is a sequence point between the evaluations of the first
-    and second operands. If the first operand compares unequal to 0, the second operand is
-    not evaluated.
-
-
-
-
-[page 99] (Contents)
-
-    6.5.15 Conditional operator
-    Syntax
-1            conditional-expression:
-                    logical-OR-expression
-                    logical-OR-expression ? expression : conditional-expression
-    Constraints
-2   The first operand shall have scalar type.
-3   One of the following shall hold for the second and third operands:
-    -- both operands have arithmetic type;
-    -- both operands have the same structure or union type;
-    -- both operands have void type;
-    -- both operands are pointers to qualified or unqualified versions of compatible types;
-    -- one operand is a pointer and the other is a null pointer constant; or
-    -- one operand is a pointer to an object type and the other is a pointer to a qualified or
-      unqualified version of void.
-    Semantics
-4   The first operand is evaluated; there is a sequence point between its evaluation and the
-    evaluation of the second or third operand (whichever is evaluated). The second operand
-    is evaluated only if the first compares unequal to 0; the third operand is evaluated only if
-    the first compares equal to 0; the result is the value of the second or third operand
-    (whichever is evaluated), converted to the type described below.109)
-5   If both the second and third operands have arithmetic type, the result type that would be
-    determined by the usual arithmetic conversions, were they applied to those two operands,
-    is the type of the result. If both the operands have structure or union type, the result has
-    that type. If both operands have void type, the result has void type.
-6   If both the second and third operands are pointers or one is a null pointer constant and the
-    other is a pointer, the result type is a pointer to a type qualified with all the type qualifiers
-    of the types referenced by both operands. Furthermore, if both operands are pointers to
-    compatible types or to differently qualified versions of compatible types, the result type is
-    a pointer to an appropriately qualified version of the composite type; if one operand is a
-    null pointer constant, the result has the type of the other operand; otherwise, one operand
-    is a pointer to void or a qualified version of void, in which case the result type is a
-    pointer to an appropriately qualified version of void.
-
-    109) A conditional expression does not yield an lvalue.
-
-[page 100] (Contents)
-
-7   EXAMPLE The common type that results when the second and third operands are pointers is determined
-    in two independent stages. The appropriate qualifiers, for example, do not depend on whether the two
-    pointers have compatible types.
-8   Given the declarations
-              const void *c_vp;
-              void *vp;
-              const int *c_ip;
-              volatile int *v_ip;
-              int *ip;
-              const char *c_cp;
-    the third column in the following table is the common type that is the result of a conditional expression in
-    which the first two columns are the second and third operands (in either order):
-              c_vp    c_ip      const void *
-              v_ip    0         volatile int *
-              c_ip    v_ip      const volatile int *
-              vp      c_cp      const void *
-              ip      c_ip      const int *
-              vp      ip        void *
-
-    6.5.16 Assignment operators
-    Syntax
-1            assignment-expression:
-                    conditional-expression
-                    unary-expression assignment-operator assignment-expression
-             assignment-operator: one of
-                    = *= /= %= +=                       -=     <<=      >>=      &=     ^=     |=
-    Constraints
-2   An assignment operator shall have a modifiable lvalue as its left operand.
-    Semantics
-3   An assignment operator stores a value in the object designated by the left operand. An
-    assignment expression has the value of the left operand after the assignment,110) but is not
-    an lvalue. The type of an assignment expression is the type of the left operand unless the
-    left operand has qualified type, in which case it is the unqualified version of the type of
-    the left operand. The side effect of updating the stored value of the left operand is
-    sequenced after the value computations of the left and right operands. The evaluations of
-    the operands are unsequenced.
-
-
-
-
-    110) The implementation is permitted to read the object to determine the value but is not required to, even
-         when the object has volatile-qualified type.
-
-[page 101] (Contents)
-
-    6.5.16.1 Simple assignment
-    Constraints
-1   One of the following shall hold:111)
-    -- the left operand has qualified or unqualified arithmetic type and the right has
-      arithmetic type;
-    -- the left operand has a qualified or unqualified version of a structure or union type
-      compatible with the type of the right;
-    -- both operands are pointers to qualified or unqualified versions of compatible types,
-      and the type pointed to by the left has all the qualifiers of the type pointed to by the
-      right;
-    -- one operand is a pointer to an object type and the other is a pointer to a qualified or
-      unqualified version of void, and the type pointed to by the left has all the qualifiers
-      of the type pointed to by the right;
-    -- the left operand is a pointer and the right is a null pointer constant; or
-    -- the left operand has type _Bool and the right is a pointer.
-    Semantics
-2   In simple assignment (=), the value of the right operand is converted to the type of the
-    assignment expression and replaces the value stored in the object designated by the left
-    operand.
-3   If the value being stored in an object is read from another object that overlaps in any way
-    the storage of the first object, then the overlap shall be exact and the two objects shall
-    have qualified or unqualified versions of a compatible type; otherwise, the behavior is
-    undefined.
-4   EXAMPLE 1       In the program fragment
-            int f(void);
-            char c;
-            /* ... */
-            if ((c = f()) == -1)
-                    /* ... */
-    the int value returned by the function may be truncated when stored in the char, and then converted back
-    to int width prior to the comparison. In an implementation in which ''plain'' char has the same range of
-    values as unsigned char (and char is narrower than int), the result of the conversion cannot be
-
-
-
-    111) The asymmetric appearance of these constraints with respect to type qualifiers is due to the conversion
-         (specified in 6.3.2.1) that changes lvalues to ''the value of the expression'' and thus removes any type
-         qualifiers that were applied to the type category of the expression (for example, it removes const but
-         not volatile from the type int volatile * const).
-
-[page 102] (Contents)
-
-    negative, so the operands of the comparison can never compare equal. Therefore, for full portability, the
-    variable c should be declared as int.
-
-5   EXAMPLE 2       In the fragment:
-            char c;
-            int i;
-            long l;
-            l = (c = i);
-    the value of i is converted to the type of the assignment expression c = i, that is, char type. The value
-    of the expression enclosed in parentheses is then converted to the type of the outer assignment expression,
-    that is, long int type.
-
-6   EXAMPLE 3       Consider the fragment:
-            const char **cpp;
-            char *p;
-            const char c = 'A';
-            cpp = &p;                  // constraint violation
-            *cpp = &c;                 // valid
-            *p = 0;                    // valid
-    The first assignment is unsafe because it would allow the following valid code to attempt to change the
-    value of the const object c.
-
-    6.5.16.2 Compound assignment
-    Constraints
-1   For the operators += and -= only, either the left operand shall be a pointer to a complete
-    object type and the right shall have integer type, or the left operand shall have qualified or
-    unqualified arithmetic type and the right shall have arithmetic type.
-2   For the other operators, each operand shall have arithmetic type consistent with those
-    allowed by the corresponding binary operator.
-    Semantics
-3   A compound assignment of the form E1 op = E2 is equivalent to the simple assignment
-    expression E1 = E1 op (E2), except that the lvalue E1 is evaluated only once, and with
-    respect to an indeterminately-sequenced function call, the operation of a compound
-    assignment is a single evaluation. If E1 has an _Atomic-qualified type, compound
-    assignment is a read-modify-write operation with memory_order_seq_cst memory
-    order semantics.112)
-
-
-
-
-[page 103] (Contents)
-
-    6.5.17 Comma operator
-    Syntax
-1            expression:
-                    assignment-expression
-                    expression , assignment-expression
-    Semantics
-2   The left operand of a comma operator is evaluated as a void expression; there is a
-    sequence point between its evaluation and that of the right operand. Then the right
-    operand is evaluated; the result has its type and value.113)
-3   EXAMPLE As indicated by the syntax, the comma operator (as described in this subclause) cannot
-    appear in contexts where a comma is used to separate items in a list (such as arguments to functions or lists
-    of initializers). On the other hand, it can be used within a parenthesized expression or within the second
-    expression of a conditional operator in such contexts. In the function call
-             f(a, (t=3, t+2), c)
-    the function has three arguments, the second of which has the value 5.
-
-    Forward references: initialization (6.7.9).
-
-
-
-
-    112) Where a pointer to an atomic object can be formed, this is equivalent to the following code sequence
-         where T is the type of E1:
-                  T tmp = E1;
-                  T result;
-                  do {
-                        result = tmp op (E2);
-                  } while (!atomic_compare_exchange_strong(&E1, &tmp, result));
-          with result being the result of the operation.
-    113) A comma operator does not yield an lvalue.
-
-[page 104] (Contents)
-
-    6.6 Constant expressions
-    Syntax
-1            constant-expression:
-                    conditional-expression
-    Description
-2   A constant expression can be evaluated during translation rather than runtime, and
-    accordingly may be used in any place that a constant may be.
-    Constraints
-3   Constant expressions shall not contain assignment, increment, decrement, function-call,
-    or comma operators, except when they are contained within a subexpression that is not
-    evaluated.114)
-4   Each constant expression shall evaluate to a constant that is in the range of representable
-    values for its type.
-    Semantics
-5   An expression that evaluates to a constant is required in several contexts. If a floating
-    expression is evaluated in the translation environment, the arithmetic precision and range
-    shall be at least as great as if the expression were being evaluated in the execution
-    environment.115)
-6   An integer constant expression116) shall have integer type and shall only have operands
-    that are integer constants, enumeration constants, character constants, sizeof
-    expressions whose results are integer constants, and floating constants that are the
-    immediate operands of casts. Cast operators in an integer constant expression shall only
-    convert arithmetic types to integer types, except as part of an operand to the sizeof
-    operator.
-7   More latitude is permitted for constant expressions in initializers. Such a constant
-    expression shall be, or evaluate to, one of the following:
-    -- an arithmetic constant expression,
-
-
-
-    114) The operand of a sizeof operator is usually not evaluated (6.5.3.4).
-    115) The use of evaluation formats as characterized by FLT_EVAL_METHOD also applies to evaluation in
-         the translation environment.
-    116) An integer constant expression is required in a number of contexts such as the size of a bit-field
-         member of a structure, the value of an enumeration constant, and the size of a non-variable length
-         array. Further constraints that apply to the integer constant expressions used in conditional-inclusion
-         preprocessing directives are discussed in 6.10.1.
-
-[page 105] (Contents)
-
-     -- a null pointer constant,
-     -- an address constant, or
-     -- an address constant for a complete object type plus or minus an integer constant
-       expression.
-8    An arithmetic constant expression shall have arithmetic type and shall only have
-     operands that are integer constants, floating constants, enumeration constants, character
-     constants, and sizeof expressions. Cast operators in an arithmetic constant expression
-     shall only convert arithmetic types to arithmetic types, except as part of an operand to a
-     sizeof operator whose result is an integer constant.
-9    An address constant is a null pointer, a pointer to an lvalue designating an object of static
-     storage duration, or a pointer to a function designator; it shall be created explicitly using
-     the unary & operator or an integer constant cast to pointer type, or implicitly by the use of
-     an expression of array or function type. The array-subscript [] and member-access .
-     and -> operators, the address & and indirection * unary operators, and pointer casts may
-     be used in the creation of an address constant, but the value of an object shall not be
-     accessed by use of these operators.
-10   An implementation may accept other forms of constant expressions.
-11   The semantic rules for the evaluation of a constant expression are the same as for
-     nonconstant expressions.117)
-     Forward references: array declarators (6.7.6.2), initialization (6.7.9).
-
-
-
-
-     117) Thus, in the following initialization,
-                    static int i = 2 || 1 / 0;
-           the expression is a valid integer constant expression with value one.
-
-[page 106] (Contents)
-
-    6.7 Declarations
-    Syntax
-1            declaration:
-                    declaration-specifiers init-declarator-listopt ;
-                    static_assert-declaration                                                      *
-             declaration-specifiers:
-                    storage-class-specifier declaration-specifiersopt
-                    type-specifier declaration-specifiersopt
-                    type-qualifier declaration-specifiersopt
-                    function-specifier declaration-specifiersopt
-                    alignment-specifier declaration-specifiersopt
-             init-declarator-list:
-                     init-declarator
-                     init-declarator-list , init-declarator
-             init-declarator:
-                     declarator
-                     declarator = initializer
-    Constraints
-2   A declaration other than a static_assert declaration shall declare at least a declarator
-    (other than the parameters of a function or the members of a structure or union), a tag, or
-    the members of an enumeration.
-3   If an identifier has no linkage, there shall be no more than one declaration of the identifier
-    (in a declarator or type specifier) with the same scope and in the same name space, except
-    that a typedef name can be redefined to denote the same type as it currently does and tags
-    may be redeclared as specified in 6.7.2.3.
-4   All declarations in the same scope that refer to the same object or function shall specify
-    compatible types.
-    Semantics
-5   A declaration specifies the interpretation and attributes of a set of identifiers. A definition
-    of an identifier is a declaration for that identifier that:
-    -- for an object, causes storage to be reserved for that object;
-    -- for a function, includes the function body;118)
-
-
-
-    118) Function definitions have a different syntax, described in 6.9.1.
-
-[page 107] (Contents)
-
-    -- for an enumeration constant or typedef name, is the (only) declaration of the
-      identifier.
-6   The declaration specifiers consist of a sequence of specifiers that indicate the linkage,
-    storage duration, and part of the type of the entities that the declarators denote. The init-
-    declarator-list is a comma-separated sequence of declarators, each of which may have
-    additional type information, or an initializer, or both. The declarators contain the
-    identifiers (if any) being declared.
-7   If an identifier for an object is declared with no linkage, the type for the object shall be *
-    complete by the end of its declarator, or by the end of its init-declarator if it has an
-    initializer; in the case of function parameters (including in prototypes), it is the adjusted
-    type (see 6.7.6.3) that is required to be complete.
-    Forward references: declarators (6.7.6), enumeration specifiers (6.7.2.2), initialization
-    (6.7.9), type names (6.7.7), type qualifiers (6.7.3).
-    6.7.1 Storage-class specifiers
-    Syntax
-1            storage-class-specifier:
-                    typedef
-                    extern
-                    static
-                    _Thread_local
-                    auto
-                    register
-    Constraints
-2   At most, one storage-class specifier may be given in the declaration specifiers in a
-    declaration, except that _Thread_local may appear with static or extern.119)
-3   In the declaration of an object with block scope, if the declaration specifiers include
-    _Thread_local, they shall also include either static or extern. If
-    _Thread_local appears in any declaration of an object, it shall be present in every
-    declaration of that object.
-    Semantics
-4   The typedef specifier is called a ''storage-class specifier'' for syntactic convenience
-    only; it is discussed in 6.7.8. The meanings of the various linkages and storage durations
-    were discussed in 6.2.2 and 6.2.4.
-
-
-
-    119) See ''future language directions'' (6.11.5).
-
-[page 108] (Contents)
-
-5   A declaration of an identifier for an object with storage-class specifier register
-    suggests that access to the object be as fast as possible. The extent to which such
-    suggestions are effective is implementation-defined.120)
-6   The declaration of an identifier for a function that has block scope shall have no explicit
-    storage-class specifier other than extern.
-7   If an aggregate or union object is declared with a storage-class specifier other than
-    typedef, the properties resulting from the storage-class specifier, except with respect to
-    linkage, also apply to the members of the object, and so on recursively for any aggregate
-    or union member objects.
-    Forward references: type definitions (6.7.8).
-    6.7.2 Type specifiers
-    Syntax
-1            type-specifier:
-                    void
-                    char
-                    short
-                    int
-                    long
-                    float
-                    double
-                    signed
-                    unsigned
-                    _Bool
-                    _Complex
-                    _Atomic ( type-name )
-                    struct-or-union-specifier
-                    enum-specifier
-                    typedef-name
-    Constraints
-2   At least one type specifier shall be given in the declaration specifiers in each declaration,
-    and in the specifier-qualifier list in each struct declaration and type name. Each list of
-
-
-    120) The implementation may treat any register declaration simply as an auto declaration. However,
-         whether or not addressable storage is actually used, the address of any part of an object declared with
-         storage-class specifier register cannot be computed, either explicitly (by use of the unary &
-         operator as discussed in 6.5.3.2) or implicitly (by converting an array name to a pointer as discussed in
-         6.3.2.1). Thus, the only operator that can be applied to an array declared with storage-class specifier
-         register is sizeof.
-
-[page 109] (Contents)
-
-    type specifiers shall be one of the following multisets (delimited by commas, when there
-    is more than one multiset per item); the type specifiers may occur in any order, possibly
-    intermixed with the other declaration specifiers.
-    -- void
-    -- char
-    -- signed char
-    -- unsigned char
-    -- short, signed short, short int, or signed short int
-    -- unsigned short, or unsigned short int
-    -- int, signed, or signed int
-    -- unsigned, or unsigned int
-    -- long, signed long, long int, or signed long int
-    -- unsigned long, or unsigned long int
-    -- long long, signed long long, long long int, or
-      signed long long int
-    -- unsigned long long, or unsigned long long int
-    -- float
-    -- double
-    -- long double
-    -- _Bool
-    -- float _Complex
-    -- double _Complex
-    -- long double _Complex
-    -- _Atomic ( type-name )
-    -- struct or union specifier
-    -- enum specifier
-    -- typedef name
-3   The type specifier _Complex shall not be used if the implementation does not support
-    complex types; likewise, _Atomic shall not be used if the implementation does not
-    support atomic types (see 6.10.8.3).
-
-
-
-[page 110] (Contents)
-
-    Semantics
-4   The _Atomic form of type specifier designates the _Atomic-qualified version of the
-    named type.
-5   Specifiers for structures, unions, and enumerations are discussed in 6.7.2.1 through
-    6.7.2.3. Declarations of typedef names are discussed in 6.7.8. The characteristics of the
-    other types are discussed in 6.2.5.
-6   Each of the comma-separated multisets designates the same type, except that for bit-
-    fields, it is implementation-defined whether the specifier int designates the same type as
-    signed int or the same type as unsigned int.
-    Forward references: enumeration specifiers (6.7.2.2), structure and union specifiers
-    (6.7.2.1), tags (6.7.2.3), type definitions (6.7.8).
-    6.7.2.1 Structure and union specifiers
-    Syntax
-1            struct-or-union-specifier:
-                     struct-or-union identifieropt { struct-declaration-list }
-                     struct-or-union identifier
-             struct-or-union:
-                     struct
-                     union
-             struct-declaration-list:
-                     struct-declaration
-                     struct-declaration-list struct-declaration
-             struct-declaration:
-                     specifier-qualifier-list struct-declarator-listopt ;
-                     static_assert-declaration
-             specifier-qualifier-list:
-                    type-specifier specifier-qualifier-listopt
-                    type-qualifier specifier-qualifier-listopt
-             struct-declarator-list:
-                     struct-declarator
-                     struct-declarator-list , struct-declarator
-             struct-declarator:
-                     declarator
-                     declaratoropt : constant-expression
-
-
-
-[page 111] (Contents)
-
-    Constraints
-2   A struct-declaration that does not declare an anonymous structure or anonymous union
-    shall contain a struct-declarator-list.
-3   A structure or union shall not contain a member with incomplete or function type (hence,
-    a structure shall not contain an instance of itself, but may contain a pointer to an instance
-    of itself), except that the last member of a structure with more than one named member
-    may have incomplete array type; such a structure (and any union containing, possibly
-    recursively, a member that is such a structure) shall not be a member of a structure or an
-    element of an array.
-4   The expression that specifies the width of a bit-field shall be an integer constant
-    expression with a nonnegative value that does not exceed the width of an object of the
-    type that would be specified were the colon and expression omitted.121) If the value is
-    zero, the declaration shall have no declarator.
-5   A bit-field shall have a type that is a qualified or unqualified version of _Bool, signed
-    int, unsigned int, or some other implementation-defined type.
-    Semantics
-6   As discussed in 6.2.5, a structure is a type consisting of a sequence of members, whose
-    storage is allocated in an ordered sequence, and a union is a type consisting of a sequence
-    of members whose storage overlap.
-7   Structure and union specifiers have the same form. The keywords struct and union
-    indicate that the type being specified is, respectively, a structure type or a union type.
-8   The presence of a struct-declaration-list in a struct-or-union-specifier declares a new type,
-    within a translation unit. The struct-declaration-list is a sequence of declarations for the
-    members of the structure or union. If the struct-declaration-list contains no named
-    members, no anonymous structures, and no anonymous unions, the behavior is undefined.
-    The type is incomplete until immediately after the } that terminates the list, and complete
-    thereafter.
-9   A member of a structure or union may have any complete object type other than a
-    variably modified type.122) In addition, a member may be declared to consist of a
-    specified number of bits (including a sign bit, if any). Such a member is called a
-    bit-field;123) its width is preceded by a colon.
-
-
-
-    121) While the number of bits in a _Bool object is at least CHAR_BIT, the width (number of sign and
-         value bits) of a _Bool may be just 1 bit.
-    122) A structure or union cannot contain a member with a variably modified type because member names
-         are not ordinary identifiers as defined in 6.2.3.
-
-[page 112] (Contents)
-
-10   A bit-field is interpreted as a signed or unsigned integer type consisting of the specified
-     number of bits.124) If the value 0 or 1 is stored into a nonzero-width bit-field of type
-     _Bool, the value of the bit-field shall compare equal to the value stored; a _Bool bit-
-     field has the semantics of a _Bool.
-11   An implementation may allocate any addressable storage unit large enough to hold a bit-
-     field. If enough space remains, a bit-field that immediately follows another bit-field in a
-     structure shall be packed into adjacent bits of the same unit. If insufficient space remains,
-     whether a bit-field that does not fit is put into the next unit or overlaps adjacent units is
-     implementation-defined. The order of allocation of bit-fields within a unit (high-order to
-     low-order or low-order to high-order) is implementation-defined. The alignment of the
-     addressable storage unit is unspecified.
-12   A bit-field declaration with no declarator, but only a colon and a width, indicates an
-     unnamed bit-field.125) As a special case, a bit-field structure member with a width of 0
-     indicates that no further bit-field is to be packed into the unit in which the previous bit-
-     field, if any, was placed.
-13   An unnamed member of structure type with no tag is called an anonymous structure; an
-     unnamed member of union type with no tag is called an anonymous union. The members
-     of an anonymous structure or union are considered to be members of the containing
-     structure or union. This applies recursively if the containing structure or union is also
-     anonymous.
-14   Each non-bit-field member of a structure or union object is aligned in an implementation-
-     defined manner appropriate to its type.
-15   Within a structure object, the non-bit-field members and the units in which bit-fields
-     reside have addresses that increase in the order in which they are declared. A pointer to a
-     structure object, suitably converted, points to its initial member (or if that member is a
-     bit-field, then to the unit in which it resides), and vice versa. There may be unnamed
-     padding within a structure object, but not at its beginning.
-16   The size of a union is sufficient to contain the largest of its members. The value of at
-     most one of the members can be stored in a union object at any time. A pointer to a
-     union object, suitably converted, points to each of its members (or if a member is a bit-
-     field, then to the unit in which it resides), and vice versa.
-
-
-     123) The unary & (address-of) operator cannot be applied to a bit-field object; thus, there are no pointers to
-          or arrays of bit-field objects.
-     124) As specified in 6.7.2 above, if the actual type specifier used is int or a typedef-name defined as int,
-          then it is implementation-defined whether the bit-field is signed or unsigned.
-     125) An unnamed bit-field structure member is useful for padding to conform to externally imposed
-          layouts.
-
-[page 113] (Contents)
-
-17   There may be unnamed padding at the end of a structure or union.
-18   As a special case, the last element of a structure with more than one named member may
-     have an incomplete array type; this is called a flexible array member. In most situations,
-     the flexible array member is ignored. In particular, the size of the structure is as if the
-     flexible array member were omitted except that it may have more trailing padding than
-     the omission would imply. However, when a . (or ->) operator has a left operand that is
-     (a pointer to) a structure with a flexible array member and the right operand names that
-     member, it behaves as if that member were replaced with the longest array (with the same
-     element type) that would not make the structure larger than the object being accessed; the
-     offset of the array shall remain that of the flexible array member, even if this would differ
-     from that of the replacement array. If this array would have no elements, it behaves as if
-     it had one element but the behavior is undefined if any attempt is made to access that
-     element or to generate a pointer one past it.
-19   EXAMPLE 1       The following illustrates anonymous structures and unions:
-              struct v {
-                    union {      // anonymous union
-                           struct { int i, j; };    // anonymous structure
-                           struct { long k, l; } w;
-                    };
-                    int m;
-              } v1;
-              v1.i = 2;   // valid
-              v1.k = 3;   // invalid: inner structure is not anonymous
-              v1.w.k = 5; // valid
-
-20   EXAMPLE 2       After the declaration:
-              struct s { int n; double d[]; };
-     the structure struct s has a flexible array member d. A typical way to use this is:
-              int m = /* some value */;
-              struct s *p = malloc(sizeof (struct s) + sizeof (double [m]));
-     and assuming that the call to malloc succeeds, the object pointed to by p behaves, for most purposes, as if
-     p had been declared as:
-              struct { int n; double d[m]; } *p;
-     (there are circumstances in which this equivalence is broken; in particular, the offsets of member d might
-     not be the same).
-21   Following the above declaration:
-              struct s t1 = { 0 };                         //   valid
-              struct s t2 = { 1, { 4.2 }};                 //   invalid
-              t1.n = 4;                                    //   valid
-              t1.d[0] = 4.2;                               //   might be undefined behavior
-     The initialization of t2 is invalid (and violates a constraint) because struct s is treated as if it did not
-     contain member d. The assignment to t1.d[0] is probably undefined behavior, but it is possible that
-
-[page 114] (Contents)
-
-              sizeof (struct s) >= offsetof(struct s, d) + sizeof (double)
-     in which case the assignment would be legitimate. Nevertheless, it cannot appear in strictly conforming
-     code.
-22   After the further declaration:
-              struct ss { int n; };
-     the expressions:
-              sizeof (struct s) >= sizeof (struct ss)
-              sizeof (struct s) >= offsetof(struct s, d)
-     are always equal to 1.
-23   If sizeof (double) is 8, then after the following code is executed:
-              struct s *s1;
-              struct s *s2;
-              s1 = malloc(sizeof (struct s) + 64);
-              s2 = malloc(sizeof (struct s) + 46);
-     and assuming that the calls to malloc succeed, the objects pointed to by s1 and s2 behave, for most
-     purposes, as if the identifiers had been declared as:
-              struct { int n; double d[8]; } *s1;
-              struct { int n; double d[5]; } *s2;
-24   Following the further successful assignments:
-              s1 = malloc(sizeof (struct s) + 10);
-              s2 = malloc(sizeof (struct s) + 6);
-     they then behave as if the declarations were:
-              struct { int n; double d[1]; } *s1, *s2;
-     and:
-              double *dp;
-              dp = &(s1->d[0]);          //   valid
-              *dp = 42;                  //   valid
-              dp = &(s2->d[0]);          //   valid
-              *dp = 42;                  //   undefined behavior
-25   The assignment:
-              *s1 = *s2;
-     only copies the member n; if any of the array elements are within the first sizeof (struct s) bytes
-     of the structure, they might be copied or simply overwritten with indeterminate values.
-
-     Forward references: declarators (6.7.6), tags (6.7.2.3).
-
-
-
-
-[page 115] (Contents)
-
-    6.7.2.2 Enumeration specifiers
-    Syntax
-1            enum-specifier:
-                   enum identifieropt { enumerator-list }
-                   enum identifieropt { enumerator-list , }
-                   enum identifier
-             enumerator-list:
-                   enumerator
-                   enumerator-list , enumerator
-             enumerator:
-                   enumeration-constant
-                   enumeration-constant = constant-expression
-    Constraints
-2   The expression that defines the value of an enumeration constant shall be an integer
-    constant expression that has a value representable as an int.
-    Semantics
-3   The identifiers in an enumerator list are declared as constants that have type int and
-    may appear wherever such are permitted.126) An enumerator with = defines its
-    enumeration constant as the value of the constant expression. If the first enumerator has
-    no =, the value of its enumeration constant is 0. Each subsequent enumerator with no =
-    defines its enumeration constant as the value of the constant expression obtained by
-    adding 1 to the value of the previous enumeration constant. (The use of enumerators with
-    = may produce enumeration constants with values that duplicate other values in the same
-    enumeration.) The enumerators of an enumeration are also known as its members.
-4   Each enumerated type shall be compatible with char, a signed integer type, or an
-    unsigned integer type. The choice of type is implementation-defined,127) but shall be
-    capable of representing the values of all the members of the enumeration. The
-    enumerated type is incomplete until immediately after the } that terminates the list of
-    enumerator declarations, and complete thereafter.
-
-
-
-
-    126) Thus, the identifiers of enumeration constants declared in the same scope shall all be distinct from
-         each other and from other identifiers declared in ordinary declarators.
-    127) An implementation may delay the choice of which integer type until all enumeration constants have
-         been seen.
-
-[page 116] (Contents)
-
-5   EXAMPLE       The following fragment:
-             enum hue { chartreuse, burgundy, claret=20, winedark };
-             enum hue col, *cp;
-             col = claret;
-             cp = &col;
-             if (*cp != burgundy)
-                   /* ... */
-    makes hue the tag of an enumeration, and then declares col as an object that has that type and cp as a
-    pointer to an object that has that type. The enumerated values are in the set { 0, 1, 20, 21 }.
-
-    Forward references: tags (6.7.2.3).
-    6.7.2.3 Tags
-    Constraints
-1   A specific type shall have its content defined at most once.
-2   Where two declarations that use the same tag declare the same type, they shall both use
-    the same choice of struct, union, or enum.
-3   A type specifier of the form
-            enum identifier
-    without an enumerator list shall only appear after the type it specifies is complete.
-    Semantics
-4   All declarations of structure, union, or enumerated types that have the same scope and
-    use the same tag declare the same type. Irrespective of whether there is a tag or what
-    other declarations of the type are in the same translation unit, the type is incomplete128)
-    until immediately after the closing brace of the list defining the content, and complete
-    thereafter.
-5   Two declarations of structure, union, or enumerated types which are in different scopes or
-    use different tags declare distinct types. Each declaration of a structure, union, or
-    enumerated type which does not include a tag declares a distinct type.
-6   A type specifier of the form
-
-
-
-
-    128) An incomplete type may only by used when the size of an object of that type is not needed. It is not
-         needed, for example, when a typedef name is declared to be a specifier for a structure or union, or
-         when a pointer to or a function returning a structure or union is being declared. (See incomplete types
-         in 6.2.5.) The specification has to be complete before such a function is called or defined.
-
-[page 117] (Contents)
-
-              struct-or-union identifieropt { struct-declaration-list }
-     or
-              enum identifieropt { enumerator-list }
-     or
-              enum identifieropt { enumerator-list , }
-     declares a structure, union, or enumerated type. The list defines the structure content,
-     union content, or enumeration content. If an identifier is provided,129) the type specifier
-     also declares the identifier to be the tag of that type.
-7    A declaration of the form
-              struct-or-union identifier ;
-     specifies a structure or union type and declares the identifier as a tag of that type.130)
-8    If a type specifier of the form
-              struct-or-union identifier
-     occurs other than as part of one of the above forms, and no other declaration of the
-     identifier as a tag is visible, then it declares an incomplete structure or union type, and
-     declares the identifier as the tag of that type.130)
-9    If a type specifier of the form
-              struct-or-union identifier
-     or
-              enum identifier
-     occurs other than as part of one of the above forms, and a declaration of the identifier as a
-     tag is visible, then it specifies the same type as that other declaration, and does not
-     redeclare the tag.
-10   EXAMPLE 1       This mechanism allows declaration of a self-referential structure.
-              struct tnode {
-                    int count;
-                    struct tnode *left, *right;
-              };
-     specifies a structure that contains an integer and two pointers to objects of the same type. Once this
-     declaration has been given, the declaration
-
-
-
-
-     129) If there is no identifier, the type can, within the translation unit, only be referred to by the declaration
-          of which it is a part. Of course, when the declaration is of a typedef name, subsequent declarations
-          can make use of that typedef name to declare objects having the specified structure, union, or
-          enumerated type.
-     130) A similar construction with enum does not exist.
-
-[page 118] (Contents)
-
-              struct tnode s, *sp;
-     declares s to be an object of the given type and sp to be a pointer to an object of the given type. With
-     these declarations, the expression sp->left refers to the left struct tnode pointer of the object to
-     which sp points; the expression s.right->count designates the count member of the right struct
-     tnode pointed to from s.
-11   The following alternative formulation uses the typedef mechanism:
-              typedef struct tnode TNODE;
-              struct tnode {
-                    int count;
-                    TNODE *left, *right;
-              };
-              TNODE s, *sp;
-
-12   EXAMPLE 2 To illustrate the use of prior declaration of a tag to specify a pair of mutually referential
-     structures, the declarations
-              struct s1 { struct s2 *s2p; /* ... */ }; // D1
-              struct s2 { struct s1 *s1p; /* ... */ }; // D2
-     specify a pair of structures that contain pointers to each other. Note, however, that if s2 were already
-     declared as a tag in an enclosing scope, the declaration D1 would refer to it, not to the tag s2 declared in
-     D2. To eliminate this context sensitivity, the declaration
-              struct s2;
-     may be inserted ahead of D1. This declares a new tag s2 in the inner scope; the declaration D2 then
-     completes the specification of the new type.
-
-     Forward references: declarators (6.7.6), type definitions (6.7.8).
-     6.7.3 Type qualifiers
-     Syntax
-1             type-qualifier:
-                     const
-                     restrict
-                     volatile
-                     _Atomic
-     Constraints
-2    Types other than pointer types whose referenced type is an object type shall not be
-     restrict-qualified.
-     Semantics
-3    The properties associated with qualified types are meaningful only for expressions that
-     are lvalues.131)
-4    If the same qualifier appears more than once in the same specifier-qualifier-list, either
-     directly or via one or more typedefs, the behavior is the same as if it appeared only
-     once.
-[page 119] (Contents)
-
-5   If an attempt is made to modify an object defined with a const-qualified type through use
-    of an lvalue with non-const-qualified type, the behavior is undefined. If an attempt is
-    made to refer to an object defined with a volatile-qualified type through use of an lvalue
-    with non-volatile-qualified type, the behavior is undefined.132) If an attempt is made to
-    refer to an object defined with an _Atomic-qualified type through use of an lvalue with
-    non-_Atomic-qualified type, the behavior is undefined.
-6   An object that has volatile-qualified type may be modified in ways unknown to the
-    implementation or have other unknown side effects. Therefore any expression referring
-    to such an object shall be evaluated strictly according to the rules of the abstract machine,
-    as described in 5.1.2.3. Furthermore, at every sequence point the value last stored in the
-    object shall agree with that prescribed by the abstract machine, except as modified by the
-    unknown factors mentioned previously.133) What constitutes an access to an object that
-    has volatile-qualified type is implementation-defined.
-7   An object that is accessed through a restrict-qualified pointer has a special association
-    with that pointer. This association, defined in 6.7.3.1 below, requires that all accesses to
-    that object use, directly or indirectly, the value of that particular pointer.134) The intended
-    use of the restrict qualifier (like the register storage class) is to promote
-    optimization, and deleting all instances of the qualifier from all preprocessing translation
-    units composing a conforming program does not change its meaning (i.e., observable
-    behavior).
-8   If the specification of an array type includes any type qualifiers, the element type is so-
-    qualified, not the array type. If the specification of a function type includes any type
-    qualifiers, the behavior is undefined.135)
-9   For two qualified types to be compatible, both shall have the identically qualified version
-    of a compatible type; the order of type qualifiers within a list of specifiers or qualifiers
-    does not affect the specified type.
-
-    131) The implementation may place a const object that is not volatile in a read-only region of
-         storage. Moreover, the implementation need not allocate storage for such an object if its address is
-         never used.
-    132) This applies to those objects that behave as if they were defined with qualified types, even if they are
-         never actually defined as objects in the program (such as an object at a memory-mapped input/output
-         address).
-    133) A volatile declaration may be used to describe an object corresponding to a memory-mapped
-         input/output port or an object accessed by an asynchronously interrupting function. Actions on
-         objects so declared shall not be ''optimized out'' by an implementation or reordered except as
-         permitted by the rules for evaluating expressions.
-    134) For example, a statement that assigns a value returned by malloc to a single pointer establishes this
-         association between the allocated object and the pointer.
-    135) Both of these can occur through the use of typedefs.
-
-[page 120] (Contents)
-
-10   EXAMPLE 1      An object declared
-             extern const volatile int real_time_clock;
-     may be modifiable by hardware, but cannot be assigned to, incremented, or decremented.
-
-11   EXAMPLE 2 The following declarations and expressions illustrate the behavior when type qualifiers
-     modify an aggregate type:
-             const struct s { int mem; } cs = { 1 };
-             struct s ncs; // the object ncs is modifiable
-             typedef int A[2][3];
-             const A a = {{4, 5, 6}, {7, 8, 9}}; // array of array of const int
-             int *pi;
-             const int *pci;
-             ncs = cs;             //    valid
-             cs = ncs;             //    violates modifiable lvalue constraint for =
-             pi = &ncs.mem;        //    valid
-             pi = &cs.mem;         //    violates type constraints for =
-             pci = &cs.mem;        //    valid
-             pi = a[0];            //    invalid: a[0] has type ''const int *''
-
-     6.7.3.1 Formal definition of restrict
-1    Let D be a declaration of an ordinary identifier that provides a means of designating an
-     object P as a restrict-qualified pointer to type T.
-2    If D appears inside a block and does not have storage class extern, let B denote the
-     block. If D appears in the list of parameter declarations of a function definition, let B
-     denote the associated block. Otherwise, let B denote the block of main (or the block of
-     whatever function is called at program startup in a freestanding environment).
-3    In what follows, a pointer expression E is said to be based on object P if (at some
-     sequence point in the execution of B prior to the evaluation of E) modifying P to point to
-     a copy of the array object into which it formerly pointed would change the value of E.136)
-     Note that ''based'' is defined only for expressions with pointer types.
-4    During each execution of B, let L be any lvalue that has &L based on P. If L is used to
-     access the value of the object X that it designates, and X is also modified (by any means),
-     then the following requirements apply: T shall not be const-qualified. Every other lvalue
-     used to access the value of X shall also have its address based on P. Every access that
-     modifies X shall be considered also to modify P, for the purposes of this subclause. If P
-     is assigned the value of a pointer expression E that is based on another restricted pointer
-     object P2, associated with block B2, then either the execution of B2 shall begin before
-
-
-     136) In other words, E depends on the value of P itself rather than on the value of an object referenced
-          indirectly through P. For example, if identifier p has type (int **restrict), then the pointer
-          expressions p and p+1 are based on the restricted pointer object designated by p, but the pointer
-          expressions *p and p[1] are not.
-
-[page 121] (Contents)
-
-     the execution of B, or the execution of B2 shall end prior to the assignment. If these
-     requirements are not met, then the behavior is undefined.
-5    Here an execution of B means that portion of the execution of the program that would
-     correspond to the lifetime of an object with scalar type and automatic storage duration
-     associated with B.
-6    A translator is free to ignore any or all aliasing implications of uses of restrict.
-7    EXAMPLE 1       The file scope declarations
-             int * restrict a;
-             int * restrict b;
-             extern int c[];
-     assert that if an object is accessed using one of a, b, or c, and that object is modified anywhere in the
-     program, then it is never accessed using either of the other two.
-
-8    EXAMPLE 2       The function parameter declarations in the following example
-             void f(int n, int * restrict p, int * restrict q)
-             {
-                   while (n-- > 0)
-                         *p++ = *q++;
-             }
-     assert that, during each execution of the function, if an object is accessed through one of the pointer
-     parameters, then it is not also accessed through the other.
-9    The benefit of the restrict qualifiers is that they enable a translator to make an effective dependence
-     analysis of function f without examining any of the calls of f in the program. The cost is that the
-     programmer has to examine all of those calls to ensure that none give undefined behavior. For example, the
-     second call of f in g has undefined behavior because each of d[1] through d[49] is accessed through
-     both p and q.
-              void g(void)
-              {
-                    extern int d[100];
-                    f(50, d + 50, d); // valid
-                    f(50, d + 1, d); // undefined behavior
-              }
-
-10   EXAMPLE 3       The function parameter declarations
-             void h(int n, int * restrict p, int * restrict q, int * restrict r)
-             {
-                   int i;
-                   for (i = 0; i < n; i++)
-                          p[i] = q[i] + r[i];
-             }
-     illustrate how an unmodified object can be aliased through two restricted pointers. In particular, if a and b
-     are disjoint arrays, a call of the form h(100, a, b, b) has defined behavior, because array b is not
-     modified within function h.
-
-11   EXAMPLE 4 The rule limiting assignments between restricted pointers does not distinguish between a
-     function call and an equivalent nested block. With one exception, only ''outer-to-inner'' assignments
-
-[page 122] (Contents)
-
-     between restricted pointers declared in nested blocks have defined behavior.
-              {
-                       int * restrict p1;
-                       int * restrict q1;
-                       p1 = q1; // undefined behavior
-                       {
-                             int * restrict p2 = p1; // valid
-                             int * restrict q2 = q1; // valid
-                             p1 = q2;                // undefined behavior
-                             p2 = q2;                // undefined behavior
-                       }
-              }
-12   The one exception allows the value of a restricted pointer to be carried out of the block in which it (or, more
-     precisely, the ordinary identifier used to designate it) is declared when that block finishes execution. For
-     example, this permits new_vector to return a vector.
-              typedef struct { int n; float * restrict v; } vector;
-              vector new_vector(int n)
-              {
-                    vector t;
-                    t.n = n;
-                    t.v = malloc(n * sizeof (float));
-                    return t;
-              }
-
-     6.7.4 Function specifiers
-     Syntax
-1             function-specifier:
-                     inline
-                     _Noreturn
-     Constraints
-2    Function specifiers shall be used only in the declaration of an identifier for a function.
-3    An inline definition of a function with external linkage shall not contain a definition of a
-     modifiable object with static or thread storage duration, and shall not contain a reference
-     to an identifier with internal linkage.
-4    In a hosted environment, no function specifier(s) shall appear in a declaration of main.
-     Semantics
-5    A function specifier may appear more than once; the behavior is the same as if it
-     appeared only once.
-6    A function declared with an inline function specifier is an inline function. Making a
-     function an inline function suggests that calls to the function be as fast as possible.137)
-     The extent to which such suggestions are effective is implementation-defined.138)
-
-[page 123] (Contents)
-
-7    Any function with internal linkage can be an inline function. For a function with external
-     linkage, the following restrictions apply: If a function is declared with an inline
-     function specifier, then it shall also be defined in the same translation unit. If all of the
-     file scope declarations for a function in a translation unit include the inline function
-     specifier without extern, then the definition in that translation unit is an inline
-     definition. An inline definition does not provide an external definition for the function,
-     and does not forbid an external definition in another translation unit. An inline definition
-     provides an alternative to an external definition, which a translator may use to implement
-     any call to the function in the same translation unit. It is unspecified whether a call to the
-     function uses the inline definition or the external definition.139)
-8    A function declared with a _Noreturn function specifier shall not return to its caller.
-     Recommended practice
-9    The implementation should produce a diagnostic message for a function declared with a
-     _Noreturn function specifier that appears to be capable of returning to its caller.
-10   EXAMPLE 1 The declaration of an inline function with external linkage can result in either an external
-     definition, or a definition available for use only within the translation unit. A file scope declaration with
-     extern creates an external definition. The following example shows an entire translation unit.
-              inline double fahr(double t)
-              {
-                    return (9.0 * t) / 5.0 + 32.0;
-              }
-              inline double cels(double t)
-              {
-                    return (5.0 * (t - 32.0)) / 9.0;
-              }
-              extern double fahr(double);                  // creates an external definition
-
-
-
-
-     137) By using, for example, an alternative to the usual function call mechanism, such as ''inline
-          substitution''. Inline substitution is not textual substitution, nor does it create a new function.
-          Therefore, for example, the expansion of a macro used within the body of the function uses the
-          definition it had at the point the function body appears, and not where the function is called; and
-          identifiers refer to the declarations in scope where the body occurs. Likewise, the function has a
-          single address, regardless of the number of inline definitions that occur in addition to the external
-          definition.
-     138) For example, an implementation might never perform inline substitution, or might only perform inline
-          substitutions to calls in the scope of an inline declaration.
-     139) Since an inline definition is distinct from the corresponding external definition and from any other
-          corresponding inline definitions in other translation units, all corresponding objects with static storage
-          duration are also distinct in each of the definitions.
-
-[page 124] (Contents)
-
-              double convert(int is_fahr, double temp)
-              {
-                    /* A translator may perform inline substitutions */
-                    return is_fahr ? cels(temp) : fahr(temp);
-              }
-11   Note that the definition of fahr is an external definition because fahr is also declared with extern, but
-     the definition of cels is an inline definition. Because cels has external linkage and is referenced, an
-     external definition has to appear in another translation unit (see 6.9); the inline definition and the external
-     definition are distinct and either may be used for the call.
-
-12   EXAMPLE 2
-              _Noreturn void f () {
-                    abort(); // ok
-              }
-              _Noreturn void g (int i) { // causes undefined behavior if i <= 0
-                    if (i > 0) abort();
-              }
-
-     Forward references: function definitions (6.9.1).
-     6.7.5 Alignment specifier
-     Syntax
-1             alignment-specifier:
-                    _Alignas ( type-name )
-                    _Alignas ( constant-expression )
-     Constraints
-2    An alignment attribute shall not be specified in a declaration of a typedef, or a bit-field, or
-     a function, or a parameter, or an object declared with the register storage-class
-     specifier.
-3    The constant expression shall be an integer constant expression. It shall evaluate to a
-     valid fundamental alignment, or to a valid extended alignment supported by the
-     implementation in the context in which it appears, or to zero.
-4    The combined effect of all alignment attributes in a declaration shall not specify an
-     alignment that is less strict than the alignment that would otherwise be required for the
-     type of the object or field being declared.
-     Semantics
-5    The first form is equivalent to _Alignas(alignof(type-name)).
-6    The alignment requirement of the declared object or field is taken to be the specified
-     alignment. An alignment specification of zero has no effect.140) When multiple
-     alignment specifiers occur in a declaration, the effective alignment requirement is the
-     strictest specified alignment.
-
-[page 125] (Contents)
-
-7   If the definition of an object has an alignment specifier, any other declaration of that
-    object shall either specify equivalent alignment or have no alignment specifier. If the
-    definition of an object does not have an alignment specifier, any other declaration of that
-    object shall also have no alignment specifier. If declarations of an object in different
-    translation units have different alignment specifiers, the behavior is undefined.
-    6.7.6 Declarators
-    Syntax
-1            declarator:
-                    pointeropt direct-declarator
-             direct-declarator:
-                     identifier
-                     ( declarator )
-                     direct-declarator [ type-qualifier-listopt assignment-expressionopt ]
-                     direct-declarator [ static type-qualifier-listopt assignment-expression ]
-                     direct-declarator [ type-qualifier-list static assignment-expression ]
-                     direct-declarator [ type-qualifier-listopt * ]
-                     direct-declarator ( parameter-type-list )
-                     direct-declarator ( identifier-listopt )
-             pointer:
-                    * type-qualifier-listopt
-                    * type-qualifier-listopt pointer
-             type-qualifier-list:
-                    type-qualifier
-                    type-qualifier-list type-qualifier
-             parameter-type-list:
-                   parameter-list
-                   parameter-list , ...
-             parameter-list:
-                   parameter-declaration
-                   parameter-list , parameter-declaration
-             parameter-declaration:
-                   declaration-specifiers declarator
-                   declaration-specifiers abstract-declaratoropt
-
-
-
-    140) An alignment specification of zero also does not affect other alignment specifications in the same
-         declaration.
-
-[page 126] (Contents)
-
-             identifier-list:
-                    identifier
-                    identifier-list , identifier
-    Semantics
-2   Each declarator declares one identifier, and asserts that when an operand of the same
-    form as the declarator appears in an expression, it designates a function or object with the
-    scope, storage duration, and type indicated by the declaration specifiers.
-3   A full declarator is a declarator that is not part of another declarator. The end of a full
-    declarator is a sequence point. If, in the nested sequence of declarators in a full
-    declarator, there is a declarator specifying a variable length array type, the type specified
-    by the full declarator is said to be variably modified. Furthermore, any type derived by
-    declarator type derivation from a variably modified type is itself variably modified.
-4   In the following subclauses, consider a declaration
-             T D1
-    where T contains the declaration specifiers that specify a type T (such as int) and D1 is
-    a declarator that contains an identifier ident. The type specified for the identifier ident in
-    the various forms of declarator is described inductively using this notation.
-5   If, in the declaration ''T D1'', D1 has the form
-             identifier
-    then the type specified for ident is T .
-6   If, in the declaration ''T D1'', D1 has the form
-             ( D )
-    then ident has the type specified by the declaration ''T D''. Thus, a declarator in
-    parentheses is identical to the unparenthesized declarator, but the binding of complicated
-    declarators may be altered by parentheses.
-    Implementation limits
-7   As discussed in 5.2.4.1, an implementation may limit the number of pointer, array, and
-    function declarators that modify an arithmetic, structure, union, or void type, either
-    directly or via one or more typedefs.
-    Forward references: array declarators (6.7.6.2), type definitions (6.7.8).
-
-
-
-
-[page 127] (Contents)
-
-    6.7.6.1 Pointer declarators
-    Semantics
-1   If, in the declaration ''T D1'', D1 has the form
-            * type-qualifier-listopt D
-    and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
-    T '', then the type specified for ident is ''derived-declarator-type-list type-qualifier-list
-    pointer to T ''. For each type qualifier in the list, ident is a so-qualified pointer.
-2   For two pointer types to be compatible, both shall be identically qualified and both shall
-    be pointers to compatible types.
-3   EXAMPLE The following pair of declarations demonstrates the difference between a ''variable pointer
-    to a constant value'' and a ''constant pointer to a variable value''.
-            const int *ptr_to_constant;
-            int *const constant_ptr;
-    The contents of any object pointed to by ptr_to_constant shall not be modified through that pointer,
-    but ptr_to_constant itself may be changed to point to another object. Similarly, the contents of the
-    int pointed to by constant_ptr may be modified, but constant_ptr itself shall always point to the
-    same location.
-4   The declaration of the constant pointer constant_ptr may be clarified by including a definition for the
-    type ''pointer to int''.
-            typedef int *int_ptr;
-            const int_ptr constant_ptr;
-    declares constant_ptr as an object that has type ''const-qualified pointer to int''.
-
-    6.7.6.2 Array declarators
-    Constraints
-1   In addition to optional type qualifiers and the keyword static, the [ and ] may delimit
-    an expression or *. If they delimit an expression (which specifies the size of an array), the
-    expression shall have an integer type. If the expression is a constant expression, it shall
-    have a value greater than zero. The element type shall not be an incomplete or function
-    type. The optional type qualifiers and the keyword static shall appear only in a
-    declaration of a function parameter with an array type, and then only in the outermost
-    array type derivation.
-2   An ordinary identifier (as defined in 6.2.3) that has a variably modified type shall have
-    either block scope and no linkage or function prototype scope. If an identifier is declared
-    to be an object with static or thread storage duration, it shall not have a variable length
-    array type.
-
-
-
-
-[page 128] (Contents)
-
-    Semantics
-3   If, in the declaration ''T D1'', D1 has one of the forms:
-             D[ type-qualifier-listopt assignment-expressionopt ]
-             D[ static type-qualifier-listopt assignment-expression ]
-             D[ type-qualifier-list static assignment-expression ]
-             D[ type-qualifier-listopt * ]
-    and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
-    T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.141)
-    (See 6.7.6.3 for the meaning of the optional type qualifiers and the keyword static.)
-4   If the size is not present, the array type is an incomplete type. If the size is * instead of
-    being an expression, the array type is a variable length array type of unspecified size,
-    which can only be used in declarations or type names with function prototype scope;142)
-    such arrays are nonetheless complete types. If the size is an integer constant expression
-    and the element type has a known constant size, the array type is not a variable length
-    array type; otherwise, the array type is a variable length array type. (Variable length
-    arrays are a conditional feature that implementations need not support; see 6.10.8.3.)
-5   If the size is an expression that is not an integer constant expression: if it occurs in a
-    declaration at function prototype scope, it is treated as if it were replaced by *; otherwise,
-    each time it is evaluated it shall have a value greater than zero. The size of each instance
-    of a variable length array type does not change during its lifetime. Where a size
-    expression is part of the operand of a sizeof operator and changing the value of the
-    size expression would not affect the result of the operator, it is unspecified whether or not
-    the size expression is evaluated.
-6   For two array types to be compatible, both shall have compatible element types, and if
-    both size specifiers are present, and are integer constant expressions, then both size
-    specifiers shall have the same constant value. If the two array types are used in a context
-    which requires them to be compatible, it is undefined behavior if the two size specifiers
-    evaluate to unequal values.
-7   EXAMPLE 1
-             float fa[11], *afp[17];
-    declares an array of float numbers and an array of pointers to float numbers.
-
-8   EXAMPLE 2       Note the distinction between the declarations
-
-
-
-
-    141) When several ''array of'' specifications are adjacent, a multidimensional array is declared.
-    142) Thus, * can be used only in function declarations that are not definitions (see 6.7.6.3).
-
-[page 129] (Contents)
-
-             extern int *x;
-             extern int y[];
-     The first declares x to be a pointer to int; the second declares y to be an array of int of unspecified size
-     (an incomplete type), the storage for which is defined elsewhere.
-
-9    EXAMPLE 3      The following declarations demonstrate the compatibility rules for variably modified types.
-             extern int n;
-             extern int m;
-             void fcompat(void)
-             {
-                   int a[n][6][m];
-                   int (*p)[4][n+1];
-                   int c[n][n][6][m];
-                   int (*r)[n][n][n+1];
-                   p = a;       // invalid: not compatible because 4 != 6
-                   r = c;       // compatible, but defined behavior only if
-                                // n == 6 and m == n+1
-             }
-
-10   EXAMPLE 4 All declarations of variably modified (VM) types have to be at either block scope or
-     function prototype scope. Array objects declared with the _Thread_local, static, or extern
-     storage-class specifier cannot have a variable length array (VLA) type. However, an object declared with
-     the static storage-class specifier can have a VM type (that is, a pointer to a VLA type). Finally, all
-     identifiers declared with a VM type have to be ordinary identifiers and cannot, therefore, be members of
-     structures or unions.
-             extern int n;
-             int A[n];                                            // invalid: file scope VLA
-             extern int (*p2)[n];                                 // invalid: file scope VM
-             int B[100];                                          // valid: file scope but not VM
-             void fvla(int m, int C[m][m]);                       // valid: VLA with prototype scope
-             void fvla(int m, int C[m][m])                        // valid: adjusted to auto pointer to VLA
-             {
-                   typedef int VLA[m][m];                         // valid: block scope typedef VLA
-                      struct tag {
-                            int (*y)[n];                          // invalid: y not ordinary identifier
-                            int z[n];                             // invalid: z not ordinary identifier
-                      };
-                      int D[m];                                   //   valid: auto VLA
-                      static int E[m];                            //   invalid: static block scope VLA
-                      extern int F[m];                            //   invalid: F has linkage and is VLA
-                      int (*s)[m];                                //   valid: auto pointer to VLA
-                      extern int (*r)[m];                         //   invalid: r has linkage and points to VLA
-                      static int (*q)[m] = &B;                    //   valid: q is a static block pointer to VLA
-             }
-
-     Forward references:           function declarators (6.7.6.3), function definitions (6.9.1),
-     initialization (6.7.9).
-
-
-
-[page 130] (Contents)
-
-     6.7.6.3 Function declarators (including prototypes)
-     Constraints
-1    A function declarator shall not specify a return type that is a function type or an array
-     type.
-2    The only storage-class specifier that shall occur in a parameter declaration is register.
-3    An identifier list in a function declarator that is not part of a definition of that function
-     shall be empty.
-4    After adjustment, the parameters in a parameter type list in a function declarator that is
-     part of a definition of that function shall not have incomplete type.
-     Semantics
-5    If, in the declaration ''T D1'', D1 has the form
-             D( parameter-type-list )
-     or
-             D( identifier-listopt )
-     and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
-     T '', then the type specified for ident is ''derived-declarator-type-list function returning
-     T ''.
-6    A parameter type list specifies the types of, and may declare identifiers for, the
-     parameters of the function.
-7    A declaration of a parameter as ''array of type'' shall be adjusted to ''qualified pointer to
-     type'', where the type qualifiers (if any) are those specified within the [ and ] of the
-     array type derivation. If the keyword static also appears within the [ and ] of the
-     array type derivation, then for each call to the function, the value of the corresponding
-     actual argument shall provide access to the first element of an array with at least as many
-     elements as specified by the size expression.
-8    A declaration of a parameter as ''function returning type'' shall be adjusted to ''pointer to
-     function returning type'', as in 6.3.2.1.
-9    If the list terminates with an ellipsis (, ...), no information about the number or types
-     of the parameters after the comma is supplied.143)
-10   The special case of an unnamed parameter of type void as the only item in the list
-     specifies that the function has no parameters.
-
-
-
-     143) The macros defined in the <stdarg.h> header (7.16) may be used to access arguments that
-          correspond to the ellipsis.
-
-[page 131] (Contents)
-
-11   If, in a parameter declaration, an identifier can be treated either as a typedef name or as a
-     parameter name, it shall be taken as a typedef name.
-12   If the function declarator is not part of a definition of that function, parameters may have
-     incomplete type and may use the [*] notation in their sequences of declarator specifiers
-     to specify variable length array types.
-13   The storage-class specifier in the declaration specifiers for a parameter declaration, if
-     present, is ignored unless the declared parameter is one of the members of the parameter
-     type list for a function definition.
-14   An identifier list declares only the identifiers of the parameters of the function. An empty
-     list in a function declarator that is part of a definition of that function specifies that the
-     function has no parameters. The empty list in a function declarator that is not part of a
-     definition of that function specifies that no information about the number or types of the
-     parameters is supplied.144)
-15   For two function types to be compatible, both shall specify compatible return types.145)
-     Moreover, the parameter type lists, if both are present, shall agree in the number of
-     parameters and in use of the ellipsis terminator; corresponding parameters shall have
-     compatible types. If one type has a parameter type list and the other type is specified by a
-     function declarator that is not part of a function definition and that contains an empty
-     identifier list, the parameter list shall not have an ellipsis terminator and the type of each
-     parameter shall be compatible with the type that results from the application of the
-     default argument promotions. If one type has a parameter type list and the other type is
-     specified by a function definition that contains a (possibly empty) identifier list, both shall
-     agree in the number of parameters, and the type of each prototype parameter shall be
-     compatible with the type that results from the application of the default argument
-     promotions to the type of the corresponding identifier. (In the determination of type
-     compatibility and of a composite type, each parameter declared with function or array
-     type is taken as having the adjusted type and each parameter declared with qualified type
-     is taken as having the unqualified version of its declared type.)
-16   EXAMPLE 1       The declaration
-              int f(void), *fip(), (*pfi)();
-     declares a function f with no parameters returning an int, a function fip with no parameter specification
-     returning a pointer to an int, and a pointer pfi to a function with no parameter specification returning an
-     int. It is especially useful to compare the last two. The binding of *fip() is *(fip()), so that the
-     declaration suggests, and the same construction in an expression requires, the calling of a function fip,
-     and then using indirection through the pointer result to yield an int. In the declarator (*pfi)(), the
-     extra parentheses are necessary to indicate that indirection through a pointer to a function yields a function
-
-
-     144) See ''future language directions'' (6.11.6).
-     145) If both function types are ''old style'', parameter types are not compared.
-
-[page 132] (Contents)
-
-     designator, which is then used to call the function; it returns an int.
-17   If the declaration occurs outside of any function, the identifiers have file scope and external linkage. If the
-     declaration occurs inside a function, the identifiers of the functions f and fip have block scope and either
-     internal or external linkage (depending on what file scope declarations for these identifiers are visible), and
-     the identifier of the pointer pfi has block scope and no linkage.
-
-18   EXAMPLE 2        The declaration
-               int (*apfi[3])(int *x, int *y);
-     declares an array apfi of three pointers to functions returning int. Each of these functions has two
-     parameters that are pointers to int. The identifiers x and y are declared for descriptive purposes only and
-     go out of scope at the end of the declaration of apfi.
-
-19   EXAMPLE 3        The declaration
-               int (*fpfi(int (*)(long), int))(int, ...);
-     declares a function fpfi that returns a pointer to a function returning an int. The function fpfi has two
-     parameters: a pointer to a function returning an int (with one parameter of type long int), and an int.
-     The pointer returned by fpfi points to a function that has one int parameter and accepts zero or more
-     additional arguments of any type.
-
-20   EXAMPLE 4        The following prototype has a variably modified parameter.
-               void addscalar(int n, int m,
-                     double a[n][n*m+300], double x);
-               int main()
-               {
-                     double b[4][308];
-                     addscalar(4, 2, b, 2.17);
-                     return 0;
-               }
-               void addscalar(int n, int m,
-                     double a[n][n*m+300], double x)
-               {
-                     for (int i = 0; i < n; i++)
-                           for (int j = 0, k = n*m+300; j < k; j++)
-                                 // a is a pointer to a VLA with n*m+300 elements
-                                 a[i][j] += x;
-               }
-
-21   EXAMPLE 5        The following are all compatible function prototype declarators.
-               double    maximum(int        n,   int   m,   double    a[n][m]);
-               double    maximum(int        n,   int   m,   double    a[*][*]);
-               double    maximum(int        n,   int   m,   double    a[ ][*]);
-               double    maximum(int        n,   int   m,   double    a[ ][m]);
-     as are:
-               void   f(double      (* restrict a)[5]);
-               void   f(double      a[restrict][5]);
-               void   f(double      a[restrict 3][5]);
-               void   f(double      a[restrict static 3][5]);
-
-
-[page 133] (Contents)
-
-    (Note that the last declaration also specifies that the argument corresponding to a in any call to f must be a
-    non-null pointer to the first of at least three arrays of 5 doubles, which the others do not.)
-
-    Forward references: function definitions (6.9.1), type names (6.7.7).
-    6.7.7 Type names
-    Syntax
-1            type-name:
-                    specifier-qualifier-list abstract-declaratoropt
-             abstract-declarator:
-                    pointer
-                    pointeropt direct-abstract-declarator
-             direct-abstract-declarator:
-                     ( abstract-declarator )
-                     direct-abstract-declaratoropt [ type-qualifier-listopt
-                                    assignment-expressionopt ]
-                     direct-abstract-declaratoropt [ static type-qualifier-listopt
-                                    assignment-expression ]
-                     direct-abstract-declaratoropt [ type-qualifier-list static
-                                    assignment-expression ]
-                     direct-abstract-declaratoropt [ * ]
-                     direct-abstract-declaratoropt ( parameter-type-listopt )
-    Semantics
-2   In several contexts, it is necessary to specify a type. This is accomplished using a type
-    name, which is syntactically a declaration for a function or an object of that type that
-    omits the identifier.146)
-3   EXAMPLE        The constructions
-             (a)      int
-             (b)      int   *
-             (c)      int   *[3]
-             (d)      int   (*)[3]
-             (e)      int   (*)[*]
-             (f)      int   *()
-             (g)      int   (*)(void)
-             (h)      int   (*const [])(unsigned int, ...)
-    name respectively the types (a) int, (b) pointer to int, (c) array of three pointers to int, (d) pointer to an
-    array of three ints, (e) pointer to a variable length array of an unspecified number of ints, (f) function
-    with no parameter specification returning a pointer to int, (g) pointer to function with no parameters
-
-
-    146) As indicated by the syntax, empty parentheses in a type name are interpreted as ''function with no
-         parameter specification'', rather than redundant parentheses around the omitted identifier.
-
-[page 134] (Contents)
-
-    returning an int, and (h) array of an unspecified number of constant pointers to functions, each with one
-    parameter that has type unsigned int and an unspecified number of other parameters, returning an
-    int.
-
-    6.7.8 Type definitions
-    Syntax
-1            typedef-name:
-                    identifier
-    Constraints
-2   If a typedef name specifies a variably modified type then it shall have block scope.
-    Semantics
-3   In a declaration whose storage-class specifier is typedef, each declarator defines an
-    identifier to be a typedef name that denotes the type specified for the identifier in the way
-    described in 6.7.6. Any array size expressions associated with variable length array
-    declarators are evaluated each time the declaration of the typedef name is reached in the
-    order of execution. A typedef declaration does not introduce a new type, only a
-    synonym for the type so specified. That is, in the following declarations:
-             typedef T type_ident;
-             type_ident D;
-    type_ident is defined as a typedef name with the type specified by the declaration
-    specifiers in T (known as T ), and the identifier in D has the type ''derived-declarator-
-    type-list T '' where the derived-declarator-type-list is specified by the declarators of D. A
-    typedef name shares the same name space as other identifiers declared in ordinary
-    declarators.
-4   EXAMPLE 1       After
-             typedef int MILES, KLICKSP();
-             typedef struct { double hi, lo; } range;
-    the constructions
-             MILES distance;
-             extern KLICKSP *metricp;
-             range x;
-             range z, *zp;
-    are all valid declarations. The type of distance is int, that of metricp is ''pointer to function with no
-    parameter specification returning int'', and that of x and z is the specified structure; zp is a pointer to
-    such a structure. The object distance has a type compatible with any other int object.
-
-5   EXAMPLE 2       After the declarations
-             typedef struct s1 { int x; } t1, *tp1;
-             typedef struct s2 { int x; } t2, *tp2;
-    type t1 and the type pointed to by tp1 are compatible. Type t1 is also compatible with type struct
-
-[page 135] (Contents)
-
-    s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int.
-
-6   EXAMPLE 3       The following obscure constructions
-             typedef signed int t;
-             typedef int plain;
-             struct tag {
-                   unsigned t:4;
-                   const t:5;
-                   plain r:5;
-             };
-    declare a typedef name t with type signed int, a typedef name plain with type int, and a structure
-    with three bit-field members, one named t that contains values in the range [0, 15], an unnamed const-
-    qualified bit-field which (if it could be accessed) would contain values in either the range [-15, +15] or
-    [-16, +15], and one named r that contains values in one of the ranges [0, 31], [-15, +15], or [-16, +15].
-    (The choice of range is implementation-defined.) The first two bit-field declarations differ in that
-    unsigned is a type specifier (which forces t to be the name of a structure member), while const is a
-    type qualifier (which modifies t which is still visible as a typedef name). If these declarations are followed
-    in an inner scope by
-             t f(t (t));
-             long t;
-    then a function f is declared with type ''function returning signed int with one unnamed parameter
-    with type pointer to function returning signed int with one unnamed parameter with type signed
-    int'', and an identifier t with type long int.
-
-7   EXAMPLE 4 On the other hand, typedef names can be used to improve code readability. All three of the
-    following declarations of the signal function specify exactly the same type, the first without making use
-    of any typedef names.
-             typedef void fv(int), (*pfv)(int);
-             void (*signal(int, void (*)(int)))(int);
-             fv *signal(int, fv *);
-             pfv signal(int, pfv);
-
-8   EXAMPLE 5 If a typedef name denotes a variable length array type, the length of the array is fixed at the
-    time the typedef name is defined, not each time it is used:
-             void copyt(int n)
-             {
-                   typedef int B[n];   //               B is n ints, n evaluated now
-                   n += 1;
-                   B a;                //               a is n ints, n without += 1
-                   int b[n];           //               a and b are different sizes
-                   for (int i = 1; i < n;               i++)
-                         a[i-1] = b[i];
-             }
-
-
-
-
-[page 136] (Contents)
-
-    6.7.9 Initialization
-    Syntax
-1            initializer:
-                      assignment-expression
-                      { initializer-list }
-                      { initializer-list , }
-             initializer-list:
-                      designationopt initializer
-                      initializer-list , designationopt initializer
-             designation:
-                    designator-list =
-             designator-list:
-                    designator
-                    designator-list designator
-             designator:
-                    [ constant-expression ]
-                    . identifier
-    Constraints
-2   No initializer shall attempt to provide a value for an object not contained within the entity
-    being initialized.
-3   The type of the entity to be initialized shall be an array of unknown size or a complete
-    object type that is not a variable length array type.
-4   All the expressions in an initializer for an object that has static or thread storage duration
-    shall be constant expressions or string literals.
-5   If the declaration of an identifier has block scope, and the identifier has external or
-    internal linkage, the declaration shall have no initializer for the identifier.
-6   If a designator has the form
-             [ constant-expression ]
-    then the current object (defined below) shall have array type and the expression shall be
-    an integer constant expression. If the array is of unknown size, any nonnegative value is
-    valid.
-7   If a designator has the form
-             . identifier
-    then the current object (defined below) shall have structure or union type and the
-    identifier shall be the name of a member of that type.
-[page 137] (Contents)
-
-     Semantics
-8    An initializer specifies the initial value stored in an object.
-9    Except where explicitly stated otherwise, for the purposes of this subclause unnamed
-     members of objects of structure and union type do not participate in initialization.
-     Unnamed members of structure objects have indeterminate value even after initialization.
-10   If an object that has automatic storage duration is not initialized explicitly, its value is
-     indeterminate. If an object that has static or thread storage duration is not initialized
-     explicitly, then:
-     -- if it has pointer type, it is initialized to a null pointer;
-     -- if it has arithmetic type, it is initialized to (positive or unsigned) zero;
-     -- if it is an aggregate, every member is initialized (recursively) according to these rules,
-       and any padding is initialized to zero bits;
-     -- if it is a union, the first named member is initialized (recursively) according to these
-       rules, and any padding is initialized to zero bits;
-11   The initializer for a scalar shall be a single expression, optionally enclosed in braces. The
-     initial value of the object is that of the expression (after conversion); the same type
-     constraints and conversions as for simple assignment apply, taking the type of the scalar
-     to be the unqualified version of its declared type.
-12   The rest of this subclause deals with initializers for objects that have aggregate or union
-     type.
-13   The initializer for a structure or union object that has automatic storage duration shall be
-     either an initializer list as described below, or a single expression that has compatible
-     structure or union type. In the latter case, the initial value of the object, including
-     unnamed members, is that of the expression.
-14   An array of character type may be initialized by a character string literal or UTF-8 string
-     literal, optionally enclosed in braces. Successive bytes of the string literal (including the
-     terminating null character if there is room or if the array is of unknown size) initialize the
-     elements of the array.
-15   An array with element type compatible with a qualified or unqualified version of
-     wchar_t may be initialized by a wide string literal, optionally enclosed in braces.
-     Successive wide characters of the wide string literal (including the terminating null wide
-     character if there is room or if the array is of unknown size) initialize the elements of the
-     array.
-16   Otherwise, the initializer for an object that has aggregate or union type shall be a brace-
-     enclosed list of initializers for the elements or named members.
-
-
-[page 138] (Contents)
-
-17   Each brace-enclosed initializer list has an associated current object. When no
-     designations are present, subobjects of the current object are initialized in order according
-     to the type of the current object: array elements in increasing subscript order, structure
-     members in declaration order, and the first named member of a union.147) In contrast, a
-     designation causes the following initializer to begin initialization of the subobject
-     described by the designator. Initialization then continues forward in order, beginning
-     with the next subobject after that described by the designator.148)
-18   Each designator list begins its description with the current object associated with the
-     closest surrounding brace pair. Each item in the designator list (in order) specifies a
-     particular member of its current object and changes the current object for the next
-     designator (if any) to be that member.149) The current object that results at the end of the
-     designator list is the subobject to be initialized by the following initializer.
-19   The initialization shall occur in initializer list order, each initializer provided for a
-     particular subobject overriding any previously listed initializer for the same subobject;150)
-     all subobjects that are not initialized explicitly shall be initialized implicitly the same as
-     objects that have static storage duration.
-20   If the aggregate or union contains elements or members that are aggregates or unions,
-     these rules apply recursively to the subaggregates or contained unions. If the initializer of
-     a subaggregate or contained union begins with a left brace, the initializers enclosed by
-     that brace and its matching right brace initialize the elements or members of the
-     subaggregate or the contained union. Otherwise, only enough initializers from the list are
-     taken to account for the elements or members of the subaggregate or the first member of
-     the contained union; any remaining initializers are left to initialize the next element or
-     member of the aggregate of which the current subaggregate or contained union is a part.
-21   If there are fewer initializers in a brace-enclosed list than there are elements or members
-     of an aggregate, or fewer characters in a string literal used to initialize an array of known
-     size than there are elements in the array, the remainder of the aggregate shall be
-     initialized implicitly the same as objects that have static storage duration.
-
-
-
-     147) If the initializer list for a subaggregate or contained union does not begin with a left brace, its
-          subobjects are initialized as usual, but the subaggregate or contained union does not become the
-          current object: current objects are associated only with brace-enclosed initializer lists.
-     148) After a union member is initialized, the next object is not the next member of the union; instead, it is
-          the next subobject of an object containing the union.
-     149) Thus, a designator can only specify a strict subobject of the aggregate or union that is associated with
-          the surrounding brace pair. Note, too, that each separate designator list is independent.
-     150) Any initializer for the subobject which is overridden and so not used to initialize that subobject might
-          not be evaluated at all.
-
-[page 139] (Contents)
-
-22   If an array of unknown size is initialized, its size is determined by the largest indexed
-     element with an explicit initializer. The array type is completed at the end of its
-     initializer list.
-23   The order in which any side effects occur among the initialization list expressions is
-     unspecified.151)
-24   EXAMPLE 1       Provided that <complex.h> has been #included, the declarations
-              int i = 3.5;
-              double complex c = 5 + 3 * I;
-     define and initialize i with the value 3 and c with the value 5.0 + i3.0.
-
-25   EXAMPLE 2       The declaration
-              int x[] = { 1, 3, 5 };
-     defines and initializes x as a one-dimensional array object that has three elements, as no size was specified
-     and there are three initializers.
-
-26   EXAMPLE 3       The declaration
-              int y[4][3] =         {
-                    { 1, 3,         5 },
-                    { 2, 4,         6 },
-                    { 3, 5,         7 },
-              };
-     is a definition with a fully bracketed initialization: 1, 3, and 5 initialize the first row of y (the array object
-     y[0]), namely y[0][0], y[0][1], and y[0][2]. Likewise the next two lines initialize y[1] and
-     y[2]. The initializer ends early, so y[3] is initialized with zeros. Precisely the same effect could have
-     been achieved by
-              int y[4][3] = {
-                    1, 3, 5, 2, 4, 6, 3, 5, 7
-              };
-     The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the
-     next three are taken successively for y[1] and y[2].
-
-27   EXAMPLE 4       The declaration
-              int z[4][3] = {
-                    { 1 }, { 2 }, { 3 }, { 4 }
-              };
-     initializes the first column of z as specified and initializes the rest with zeros.
-
-28   EXAMPLE 5       The declaration
-              struct { int a[3], b; } w[] = { { 1 }, 2 };
-     is a definition with an inconsistently bracketed initialization. It defines an array with two element
-     structures: w[0].a[0] is 1 and w[1].a[0] is 2; all the other elements are zero.
-
-
-
-     151) In particular, the evaluation order need not be the same as the order of subobject initialization.
-
-[page 140] (Contents)
-
-29   EXAMPLE 6         The declaration
-               short q[4][3][2] = {
-                     { 1 },
-                     { 2, 3 },
-                     { 4, 5, 6 }
-               };
-     contains an incompletely but consistently bracketed initialization. It defines a three-dimensional array
-     object: q[0][0][0] is 1, q[1][0][0] is 2, q[1][0][1] is 3, and 4, 5, and 6 initialize
-     q[2][0][0], q[2][0][1], and q[2][1][0], respectively; all the rest are zero. The initializer for
-     q[0][0] does not begin with a left brace, so up to six items from the current list may be used. There is
-     only one, so the values for the remaining five elements are initialized with zero. Likewise, the initializers
-     for q[1][0] and q[2][0] do not begin with a left brace, so each uses up to six items, initializing their
-     respective two-dimensional subaggregates. If there had been more than six items in any of the lists, a
-     diagnostic message would have been issued. The same initialization result could have been achieved by:
-               short q[4][3][2] = {
-                     1, 0, 0, 0, 0, 0,
-                     2, 3, 0, 0, 0, 0,
-                     4, 5, 6
-               };
-     or by:
-               short q[4][3][2] = {
-                     {
-                           { 1 },
-                     },
-                     {
-                           { 2, 3 },
-                     },
-                     {
-                           { 4, 5 },
-                           { 6 },
-                     }
-               };
-     in a fully bracketed form.
-30   Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to
-     cause confusion.
-
-31   EXAMPLE 7         One form of initialization that completes array types involves typedef names. Given the
-     declaration
-               typedef int A[];             // OK - declared with block scope
-     the declaration
-               A a = { 1, 2 }, b = { 3, 4, 5 };
-     is identical to
-               int a[] = { 1, 2 }, b[] = { 3, 4, 5 };
-     due to the rules for incomplete types.
-
-
-
-[page 141] (Contents)
-
-32   EXAMPLE 8       The declaration
-              char s[] = "abc", t[3] = "abc";
-     defines ''plain'' char array objects s and t whose elements are initialized with character string literals.
-     This declaration is identical to
-              char s[] = { 'a', 'b', 'c', '\0' },
-                   t[] = { 'a', 'b', 'c' };
-     The contents of the arrays are modifiable. On the other hand, the declaration
-              char *p = "abc";
-     defines p with type ''pointer to char'' and initializes it to point to an object with type ''array of char''
-     with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to
-     modify the contents of the array, the behavior is undefined.
-
-33   EXAMPLE 9       Arrays can be initialized to correspond to the elements of an enumeration by using
-     designators:
-              enum { member_one,           member_two };
-              const char *nm[] =           {
-                    [member_two]           = "member two",
-                    [member_one]           = "member one",
-              };
-
-34   EXAMPLE 10       Structure members can be initialized to nonzero values without depending on their order:
-              div_t answer = { .quot = 2, .rem = -1 };
-
-35   EXAMPLE 11 Designators can be used to provide explicit initialization when unadorned initializer lists
-     might be misunderstood:
-              struct { int a[3], b; } w[] =
-                    { [0].a = {1}, [1].a[0] = 2 };
-
-36   EXAMPLE 12       Space can be ''allocated'' from both ends of an array by using a single designator:
-              int a[MAX] = {
-                    1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
-              };
-37   In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less
-     than ten, some of the values provided by the first five initializers will be overridden by the second five.
-
-38   EXAMPLE 13       Any member of a union can be initialized:
-              union { /* ... */ } u = { .any_member = 42 };
-
-     Forward references: common definitions <stddef.h> (7.19).
-
-
-
-
-[page 142] (Contents)
-
-    6.7.10 Static assertions
-    Syntax
-1            static_assert-declaration:
-                     _Static_assert ( constant-expression , string-literal ) ;
-    Constraints
-2   The constant expression shall compare unequal to 0.
-    Semantics
-3   The constant expression shall be an integer constant expression. If the value of the
-    constant expression compares unequal to 0, the declaration has no effect. Otherwise, the
-    constraint is violated and the implementation shall produce a diagnostic message that
-    includes the text of the string literal, except that characters not in the basic source
-    character set are not required to appear in the message.
-    Forward references: diagnostics (7.2).
-
-
-
-
-[page 143] (Contents)
-
-    6.8 Statements and blocks
-    Syntax
-1            statement:
-                    labeled-statement
-                    compound-statement
-                    expression-statement
-                    selection-statement
-                    iteration-statement
-                    jump-statement
-    Semantics
-2   A statement specifies an action to be performed. Except as indicated, statements are
-    executed in sequence.
-3   A block allows a set of declarations and statements to be grouped into one syntactic unit.
-    The initializers of objects that have automatic storage duration, and the variable length
-    array declarators of ordinary identifiers with block scope, are evaluated and the values are
-    stored in the objects (including storing an indeterminate value in objects without an
-    initializer) each time the declaration is reached in the order of execution, as if it were a
-    statement, and within each declaration in the order that declarators appear.
-4   A full expression is an expression that is not part of another expression or of a declarator.
-    Each of the following is a full expression: an initializer that is not part of a compound
-    literal; the expression in an expression statement; the controlling expression of a selection
-    statement (if or switch); the controlling expression of a while or do statement; each
-    of the (optional) expressions of a for statement; the (optional) expression in a return
-    statement. There is a sequence point between the evaluation of a full expression and the
-    evaluation of the next full expression to be evaluated.
-    Forward references: expression and null statements (6.8.3), selection statements
-    (6.8.4), iteration statements (6.8.5), the return statement (6.8.6.4).
-    6.8.1 Labeled statements
-    Syntax
-1            labeled-statement:
-                    identifier : statement
-                    case constant-expression : statement
-                    default : statement
-    Constraints
-2   A case or default label shall appear only in a switch statement. Further
-    constraints on such labels are discussed under the switch statement.
-
-[page 144] (Contents)
-
-3   Label names shall be unique within a function.
-    Semantics
-4   Any statement may be preceded by a prefix that declares an identifier as a label name.
-    Labels in themselves do not alter the flow of control, which continues unimpeded across
-    them.
-    Forward references: the goto statement (6.8.6.1), the switch statement (6.8.4.2).
-    6.8.2 Compound statement
-    Syntax
-1            compound-statement:
-                   { block-item-listopt }
-             block-item-list:
-                     block-item
-                     block-item-list block-item
-             block-item:
-                     declaration
-                     statement
-    Semantics
-2   A compound statement is a block.
-    6.8.3 Expression and null statements
-    Syntax
-1            expression-statement:
-                    expressionopt ;
-    Semantics
-2   The expression in an expression statement is evaluated as a void expression for its side
-    effects.152)
-3   A null statement (consisting of just a semicolon) performs no operations.
-4   EXAMPLE 1 If a function call is evaluated as an expression statement for its side effects only, the
-    discarding of its value may be made explicit by converting the expression to a void expression by means of
-    a cast:
-             int p(int);
-             /* ... */
-             (void)p(0);
-
-
-
-    152) Such as assignments, and function calls which have side effects.
-
-[page 145] (Contents)
-
-5   EXAMPLE 2       In the program fragment
-             char *s;
-             /* ... */
-             while (*s++ != '\0')
-                     ;
-    a null statement is used to supply an empty loop body to the iteration statement.
-
-6   EXAMPLE 3       A null statement may also be used to carry a label just before the closing } of a compound
-    statement.
-             while (loop1) {
-                   /* ... */
-                   while (loop2) {
-                           /* ... */
-                           if (want_out)
-                                   goto end_loop1;
-                           /* ... */
-                   }
-                   /* ... */
-             end_loop1: ;
-             }
-
-    Forward references: iteration statements (6.8.5).
-    6.8.4 Selection statements
-    Syntax
-1            selection-statement:
-                     if ( expression ) statement
-                     if ( expression ) statement else statement
-                     switch ( expression ) statement
-    Semantics
-2   A selection statement selects among a set of statements depending on the value of a
-    controlling expression.
-3   A selection statement is a block whose scope is a strict subset of the scope of its
-    enclosing block. Each associated substatement is also a block whose scope is a strict
-    subset of the scope of the selection statement.
-    6.8.4.1 The if statement
-    Constraints
-1   The controlling expression of an if statement shall have scalar type.
-    Semantics
-2   In both forms, the first substatement is executed if the expression compares unequal to 0.
-    In the else form, the second substatement is executed if the expression compares equal
-
-
-[page 146] (Contents)
-
-    to 0. If the first substatement is reached via a label, the second substatement is not
-    executed.
-3   An else is associated with the lexically nearest preceding if that is allowed by the
-    syntax.
-    6.8.4.2 The switch statement
-    Constraints
-1   The controlling expression of a switch statement shall have integer type.
-2   If a switch statement has an associated case or default label within the scope of an
-    identifier with a variably modified type, the entire switch statement shall be within the
-    scope of that identifier.153)
-3   The expression of each case label shall be an integer constant expression and no two of
-    the case constant expressions in the same switch statement shall have the same value
-    after conversion. There may be at most one default label in a switch statement.
-    (Any enclosed switch statement may have a default label or case constant
-    expressions with values that duplicate case constant expressions in the enclosing
-    switch statement.)
-    Semantics
-4   A switch statement causes control to jump to, into, or past the statement that is the
-    switch body, depending on the value of a controlling expression, and on the presence of a
-    default label and the values of any case labels on or in the switch body. A case or
-    default label is accessible only within the closest enclosing switch statement.
-5   The integer promotions are performed on the controlling expression. The constant
-    expression in each case label is converted to the promoted type of the controlling
-    expression. If a converted value matches that of the promoted controlling expression,
-    control jumps to the statement following the matched case label. Otherwise, if there is
-    a default label, control jumps to the labeled statement. If no converted case constant
-    expression matches and there is no default label, no part of the switch body is
-    executed.
-    Implementation limits
-6   As discussed in 5.2.4.1, the implementation may limit the number of case values in a
-    switch statement.
-
-
-
-
-    153) That is, the declaration either precedes the switch statement, or it follows the last case or
-         default label associated with the switch that is in the block containing the declaration.
-
-[page 147] (Contents)
-
-7   EXAMPLE        In the artificial program fragment
-             switch (expr)
-             {
-                   int i = 4;
-                   f(i);
-             case 0:
-                   i = 17;
-                   /* falls through into default code */
-             default:
-                   printf("%d\n", i);
-             }
-    the object whose identifier is i exists with automatic storage duration (within the block) but is never
-    initialized, and thus if the controlling expression has a nonzero value, the call to the printf function will
-    access an indeterminate value. Similarly, the call to the function f cannot be reached.
-
-    6.8.5 Iteration statements
-    Syntax
-1            iteration-statement:
-                     while ( expression ) statement
-                     do statement while ( expression ) ;
-                     for ( expressionopt ; expressionopt ; expressionopt ) statement
-                     for ( declaration expressionopt ; expressionopt ) statement
-    Constraints
-2   The controlling expression of an iteration statement shall have scalar type.
-3   The declaration part of a for statement shall only declare identifiers for objects having
-    storage class auto or register.
-    Semantics
-4   An iteration statement causes a statement called the loop body to be executed repeatedly
-    until the controlling expression compares equal to 0. The repetition occurs regardless of
-    whether the loop body is entered from the iteration statement or by a jump.154)
-5   An iteration statement is a block whose scope is a strict subset of the scope of its
-    enclosing block. The loop body is also a block whose scope is a strict subset of the scope
-    of the iteration statement.
-6   An iteration statement that performs no input/output operations, does not access volatile
-    objects, and performs no synchronization or atomic operations in its body, controlling
-    expression, or (in the case of a for statement) its expression-3, may be assumed by the
-    implementation to terminate.155)
-
-    154) Code jumped over is not executed. In particular, the controlling expression of a for or while
-         statement is not evaluated before entering the loop body, nor is clause-1 of a for statement.
-
-[page 148] (Contents)
-
-    6.8.5.1 The while statement
-1   The evaluation of the controlling expression takes place before each execution of the loop
-    body.
-    6.8.5.2 The do statement
-1   The evaluation of the controlling expression takes place after each execution of the loop
-    body.
-    6.8.5.3 The for statement
-1   The statement
-             for ( clause-1 ; expression-2 ; expression-3 ) statement
-    behaves as follows: The expression expression-2 is the controlling expression that is
-    evaluated before each execution of the loop body. The expression expression-3 is
-    evaluated as a void expression after each execution of the loop body. If clause-1 is a
-    declaration, the scope of any identifiers it declares is the remainder of the declaration and
-    the entire loop, including the other two expressions; it is reached in the order of execution
-    before the first evaluation of the controlling expression. If clause-1 is an expression, it is
-    evaluated as a void expression before the first evaluation of the controlling expression.156)
-2   Both clause-1 and expression-3 can be omitted. An omitted expression-2 is replaced by a
-    nonzero constant.
-    6.8.6 Jump statements
-    Syntax
-1            jump-statement:
-                    goto identifier ;
-                    continue ;
-                    break ;
-                    return expressionopt ;
-    Semantics
-2   A jump statement causes an unconditional jump to another place.
-
-
-
-
-    155) This is intended to allow compiler transformations such as removal of empty loops even when
-         termination cannot be proven.
-    156) Thus, clause-1 specifies initialization for the loop, possibly declaring one or more variables for use in
-         the loop; the controlling expression, expression-2, specifies an evaluation made before each iteration,
-         such that execution of the loop continues until the expression compares equal to 0; and expression-3
-         specifies an operation (such as incrementing) that is performed after each iteration.
-
-[page 149] (Contents)
-
-    6.8.6.1 The goto statement
-    Constraints
-1   The identifier in a goto statement shall name a label located somewhere in the enclosing
-    function. A goto statement shall not jump from outside the scope of an identifier having
-    a variably modified type to inside the scope of that identifier.
-    Semantics
-2   A goto statement causes an unconditional jump to the statement prefixed by the named
-    label in the enclosing function.
-3   EXAMPLE 1 It is sometimes convenient to jump into the middle of a complicated set of statements. The
-    following outline presents one possible approach to a problem based on these three assumptions:
-      1.   The general initialization code accesses objects only visible to the current function.
-      2.   The general initialization code is too large to warrant duplication.
-      3. The code to determine the next operation is at the head of the loop. (To allow it to be reached by
-         continue statements, for example.)
-            /* ... */
-            goto first_time;
-            for (;;) {
-                    // determine next operation
-                    /* ... */
-                    if (need to reinitialize) {
-                            // reinitialize-only code
-                            /* ... */
-                    first_time:
-                            // general initialization code
-                            /* ... */
-                            continue;
-                    }
-                    // handle other operations
-                    /* ... */
-            }
-
-
-
-
-[page 150] (Contents)
-
-4   EXAMPLE 2 A goto statement is not allowed to jump past any declarations of objects with variably
-    modified types. A jump within the scope, however, is permitted.
-            goto lab3;                         // invalid: going INTO scope of VLA.
-            {
-                  double a[n];
-                  a[j] = 4.4;
-            lab3:
-                  a[j] = 3.3;
-                  goto lab4;                   // valid: going WITHIN scope of VLA.
-                  a[j] = 5.5;
-            lab4:
-                  a[j] = 6.6;
-            }
-            goto lab4;                         // invalid: going INTO scope of VLA.
-
-    6.8.6.2 The continue statement
-    Constraints
-1   A continue statement shall appear only in or as a loop body.
-    Semantics
-2   A continue statement causes a jump to the loop-continuation portion of the smallest
-    enclosing iteration statement; that is, to the end of the loop body. More precisely, in each
-    of the statements
-    while (/* ... */) {                  do {                                 for (/* ... */) {
-       /* ... */                            /* ... */                            /* ... */
-       continue;                            continue;                            continue;
-       /* ... */                            /* ... */                            /* ... */
-    contin: ;                            contin: ;                            contin: ;
-    }                                    } while (/* ... */);                 }
-    unless the continue statement shown is in an enclosed iteration statement (in which
-    case it is interpreted within that statement), it is equivalent to goto contin;.157)
-    6.8.6.3 The break statement
-    Constraints
-1   A break statement shall appear only in or as a switch body or loop body.
-    Semantics
-2   A break statement terminates execution of the smallest enclosing switch or iteration
-    statement.
-
-
-
-    157) Following the contin: label is a null statement.
-
-[page 151] (Contents)
-
-    6.8.6.4 The return statement
-    Constraints
-1   A return statement with an expression shall not appear in a function whose return type
-    is void. A return statement without an expression shall only appear in a function
-    whose return type is void.
-    Semantics
-2   A return statement terminates execution of the current function and returns control to
-    its caller. A function may have any number of return statements.
-3   If a return statement with an expression is executed, the value of the expression is
-    returned to the caller as the value of the function call expression. If the expression has a
-    type different from the return type of the function in which it appears, the value is
-    converted as if by assignment to an object having the return type of the function.158)
-4   EXAMPLE       In:
-            struct s { double i; } f(void);
-            union {
-                  struct {
-                        int f1;
-                        struct s f2;
-                  } u1;
-                  struct {
-                        struct s f3;
-                        int f4;
-                  } u2;
-            } g;
-            struct s f(void)
-            {
-                  return g.u1.f2;
-            }
-            /* ... */
-            g.u2.f3 = f();
-    there is no undefined behavior, although there would be if the assignment were done directly (without using
-    a function call to fetch the value).
-
-
-
-
-    158) The return statement is not an assignment. The overlap restriction of subclause 6.5.16.1 does not
-         apply to the case of function return. The representation of floating-point values may have wider range
-         or precision than implied by the type; a cast may be used to remove this extra range and precision.
-
-[page 152] (Contents)
-
-    6.9 External definitions
-    Syntax
-1            translation-unit:
-                     external-declaration
-                     translation-unit external-declaration
-             external-declaration:
-                    function-definition
-                    declaration
-    Constraints
-2   The storage-class specifiers auto and register shall not appear in the declaration
-    specifiers in an external declaration.
-3   There shall be no more than one external definition for each identifier declared with
-    internal linkage in a translation unit. Moreover, if an identifier declared with internal
-    linkage is used in an expression (other than as a part of the operand of a sizeof
-    operator whose result is an integer constant), there shall be exactly one external definition
-    for the identifier in the translation unit.
-    Semantics
-4   As discussed in 5.1.1.1, the unit of program text after preprocessing is a translation unit,
-    which consists of a sequence of external declarations. These are described as ''external''
-    because they appear outside any function (and hence have file scope). As discussed in
-    6.7, a declaration that also causes storage to be reserved for an object or a function named
-    by the identifier is a definition.
-5   An external definition is an external declaration that is also a definition of a function
-    (other than an inline definition) or an object. If an identifier declared with external
-    linkage is used in an expression (other than as part of the operand of a sizeof operator
-    whose result is an integer constant), somewhere in the entire program there shall be
-    exactly one external definition for the identifier; otherwise, there shall be no more than
-    one.159)
-
-
-
-
-    159) Thus, if an identifier declared with external linkage is not used in an expression, there need be no
-         external definition for it.
-
-[page 153] (Contents)
-
-    6.9.1 Function definitions
-    Syntax
-1            function-definition:
-                    declaration-specifiers declarator declaration-listopt compound-statement
-             declaration-list:
-                    declaration
-                    declaration-list declaration
-    Constraints
-2   The identifier declared in a function definition (which is the name of the function) shall
-    have a function type, as specified by the declarator portion of the function definition.160)
-3   The return type of a function shall be void or a complete object type other than array
-    type.
-4   The storage-class specifier, if any, in the declaration specifiers shall be either extern or
-    static.
-5   If the declarator includes a parameter type list, the declaration of each parameter shall
-    include an identifier, except for the special case of a parameter list consisting of a single
-    parameter of type void, in which case there shall not be an identifier. No declaration list
-    shall follow.
-6   If the declarator includes an identifier list, each declaration in the declaration list shall
-    have at least one declarator, those declarators shall declare only identifiers from the
-    identifier list, and every identifier in the identifier list shall be declared. An identifier
-    declared as a typedef name shall not be redeclared as a parameter. The declarations in the
-    declaration list shall contain no storage-class specifier other than register and no
-    initializations.
-
-
-
-    160) The intent is that the type category in a function definition cannot be inherited from a typedef:
-                  typedef int F(void);                          //   type F is ''function with no parameters
-                                                                //                  returning int''
-                  F f, g;                                       //   f and g both have type compatible with F
-                  F f { /* ... */ }                             //   WRONG: syntax/constraint error
-                  F g() { /* ... */ }                           //   WRONG: declares that g returns a function
-                  int f(void) { /* ... */ }                     //   RIGHT: f has type compatible with F
-                  int g() { /* ... */ }                         //   RIGHT: g has type compatible with F
-                  F *e(void) { /* ... */ }                      //   e returns a pointer to a function
-                  F *((e))(void) { /* ... */ }                  //   same: parentheses irrelevant
-                  int (*fp)(void);                              //   fp points to a function that has type F
-                  F *Fp;                                        //   Fp points to a function that has type F
-
-
-[page 154] (Contents)
-
-     Semantics
-7    The declarator in a function definition specifies the name of the function being defined
-     and the identifiers of its parameters. If the declarator includes a parameter type list, the
-     list also specifies the types of all the parameters; such a declarator also serves as a
-     function prototype for later calls to the same function in the same translation unit. If the
-     declarator includes an identifier list,161) the types of the parameters shall be declared in a
-     following declaration list. In either case, the type of each parameter is adjusted as
-     described in 6.7.6.3 for a parameter type list; the resulting type shall be a complete object
-     type.
-8    If a function that accepts a variable number of arguments is defined without a parameter
-     type list that ends with the ellipsis notation, the behavior is undefined.
-9    Each parameter has automatic storage duration; its identifier is an lvalue.162) The layout
-     of the storage for parameters is unspecified.
-10   On entry to the function, the size expressions of each variably modified parameter are
-     evaluated and the value of each argument expression is converted to the type of the
-     corresponding parameter as if by assignment. (Array expressions and function
-     designators as arguments were converted to pointers before the call.)
-11   After all parameters have been assigned, the compound statement that constitutes the
-     body of the function definition is executed.
-12   If the } that terminates a function is reached, and the value of the function call is used by
-     the caller, the behavior is undefined.
-13   EXAMPLE 1       In the following:
-              extern int max(int a, int b)
-              {
-                    return a > b ? a : b;
-              }
-     extern is the storage-class specifier and int is the type specifier; max(int a, int b) is the
-     function declarator; and
-              { return a > b ? a : b; }
-     is the function body. The following similar definition uses the identifier-list form for the parameter
-     declarations:
-
-
-
-
-     161) See ''future language directions'' (6.11.7).
-     162) A parameter identifier cannot be redeclared in the function body except in an enclosed block.
-
-[page 155] (Contents)
-
-              extern int max(a, b)
-              int a, b;
-              {
-                    return a > b ? a : b;
-              }
-     Here int a, b; is the declaration list for the parameters. The difference between these two definitions is
-     that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls
-     to the function, whereas the second form does not.
-
-14   EXAMPLE 2           To pass one function to another, one might say
-                          int f(void);
-                          /* ... */
-                          g(f);
-     Then the definition of g might read
-              void g(int (*funcp)(void))
-              {
-                    /* ... */
-                    (*funcp)(); /* or funcp(); ...                    */
-              }
-     or, equivalently,
-              void g(int func(void))
-              {
-                    /* ... */
-                    func(); /* or (*func)(); ...                   */
-              }
-
-     6.9.2 External object definitions
-     Semantics
-1    If the declaration of an identifier for an object has file scope and an initializer, the
-     declaration is an external definition for the identifier.
-2    A declaration of an identifier for an object that has file scope without an initializer, and
-     without a storage-class specifier or with the storage-class specifier static, constitutes a
-     tentative definition. If a translation unit contains one or more tentative definitions for an
-     identifier, and the translation unit contains no external definition for that identifier, then
-     the behavior is exactly as if the translation unit contains a file scope declaration of that
-     identifier, with the composite type as of the end of the translation unit, with an initializer
-     equal to 0.
-3    If the declaration of an identifier for an object is a tentative definition and has internal
-     linkage, the declared type shall not be an incomplete type.
-
-
-
-
-[page 156] (Contents)
-
-4   EXAMPLE 1
-             int i1 = 1;                    // definition, external linkage
-             static int i2 = 2;             // definition, internal linkage
-             extern int i3 = 3;             // definition, external linkage
-             int i4;                        // tentative definition, external linkage
-             static int i5;                 // tentative definition, internal linkage
-             int   i1;                      // valid tentative definition, refers to previous
-             int   i2;                      // 6.2.2 renders undefined, linkage disagreement
-             int   i3;                      // valid tentative definition, refers to previous
-             int   i4;                      // valid tentative definition, refers to previous
-             int   i5;                      // 6.2.2 renders undefined, linkage disagreement
-             extern    int   i1;            // refers to previous, whose linkage is external
-             extern    int   i2;            // refers to previous, whose linkage is internal
-             extern    int   i3;            // refers to previous, whose linkage is external
-             extern    int   i4;            // refers to previous, whose linkage is external
-             extern    int   i5;            // refers to previous, whose linkage is internal
-
-5   EXAMPLE 2       If at the end of the translation unit containing
-             int i[];
-    the array i still has incomplete type, the implicit initializer causes it to have one element, which is set to
-    zero on program startup.
-
-
-
-
-[page 157] (Contents)
-
-    6.10 Preprocessing directives
-    Syntax
-1            preprocessing-file:
-                    groupopt
-             group:
-                      group-part
-                      group group-part
-             group-part:
-                    if-section
-                    control-line
-                    text-line
-                    # non-directive
-             if-section:
-                      if-group elif-groupsopt else-groupopt endif-line
-             if-group:
-                     # if     constant-expression new-line groupopt
-                     # ifdef identifier new-line groupopt
-                     # ifndef identifier new-line groupopt
-             elif-groups:
-                     elif-group
-                     elif-groups elif-group
-             elif-group:
-                     # elif        constant-expression new-line groupopt
-             else-group:
-                     # else        new-line groupopt
-             endif-line:
-                     # endif       new-line
-
-
-
-
-[page 158] (Contents)
-
-             control-line:
-                    # include pp-tokens new-line
-                    # define identifier replacement-list new-line
-                    # define identifier lparen identifier-listopt )
-                                                    replacement-list new-line
-                    # define identifier lparen ... ) replacement-list new-line
-                    # define identifier lparen identifier-list , ... )
-                                                    replacement-list new-line
-                    # undef   identifier new-line
-                    # line    pp-tokens new-line
-                    # error   pp-tokensopt new-line
-                    # pragma pp-tokensopt new-line
-                    #         new-line
-             text-line:
-                     pp-tokensopt new-line
-             non-directive:
-                    pp-tokens new-line
-             lparen:
-                       a ( character not immediately preceded by white-space
-             replacement-list:
-                    pp-tokensopt
-             pp-tokens:
-                    preprocessing-token
-                    pp-tokens preprocessing-token
-             new-line:
-                    the new-line character
-    Description
-2   A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the
-    following constraints: The first token in the sequence is a # preprocessing token that (at
-    the start of translation phase 4) is either the first character in the source file (optionally
-    after white space containing no new-line characters) or that follows white space
-    containing at least one new-line character. The last token in the sequence is the first new-
-    line character that follows the first token in the sequence.163) A new-line character ends
-    the preprocessing directive even if it occurs within what would otherwise be an
-
-    163) Thus, preprocessing directives are commonly called ''lines''. These ''lines'' have no other syntactic
-         significance, as all white space is equivalent except in certain situations during preprocessing (see the
-         # character string literal creation operator in 6.10.3.2, for example).
-
-[page 159] (Contents)
-
-    invocation of a function-like macro.
-3   A text line shall not begin with a # preprocessing token. A non-directive shall not begin
-    with any of the directive names appearing in the syntax.
-4   When in a group that is skipped (6.10.1), the directive syntax is relaxed to allow any
-    sequence of preprocessing tokens to occur between the directive name and the following
-    new-line character.
-    Constraints
-5   The only white-space characters that shall appear between preprocessing tokens within a
-    preprocessing directive (from just after the introducing # preprocessing token through
-    just before the terminating new-line character) are space and horizontal-tab (including
-    spaces that have replaced comments or possibly other white-space characters in
-    translation phase 3).
-    Semantics
-6   The implementation can process and skip sections of source files conditionally, include
-    other source files, and replace macros. These capabilities are called preprocessing,
-    because conceptually they occur before translation of the resulting translation unit.
-7   The preprocessing tokens within a preprocessing directive are not subject to macro
-    expansion unless otherwise stated.
-8   EXAMPLE        In:
-             #define EMPTY
-             EMPTY # include <file.h>
-    the sequence of preprocessing tokens on the second line is not a preprocessing directive, because it does not
-    begin with a # at the start of translation phase 4, even though it will do so after the macro EMPTY has been
-    replaced.
-
-    6.10.1 Conditional inclusion
-    Constraints
-1   The expression that controls conditional inclusion shall be an integer constant expression
-    except that: identifiers (including those lexically identical to keywords) are interpreted as
-    described below;164) and it may contain unary operator expressions of the form
-         defined identifier
-    or
-         defined ( identifier )
-    which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is
-
-
-    164) Because the controlling constant expression is evaluated during translation phase 4, all identifiers
-         either are or are not macro names -- there simply are no keywords, enumeration constants, etc.
-
-[page 160] (Contents)
-
-    predefined or if it has been the subject of a #define preprocessing directive without an
-    intervening #undef directive with the same subject identifier), 0 if it is not.
-2   Each preprocessing token that remains (in the list of preprocessing tokens that will
-    become the controlling expression) after all macro replacements have occurred shall be in
-    the lexical form of a token (6.4).
-    Semantics
-3   Preprocessing directives of the forms
-       # if   constant-expression new-line groupopt
-       # elif constant-expression new-line groupopt
-    check whether the controlling constant expression evaluates to nonzero.
-4   Prior to evaluation, macro invocations in the list of preprocessing tokens that will become
-    the controlling constant expression are replaced (except for those macro names modified
-    by the defined unary operator), just as in normal text. If the token defined is
-    generated as a result of this replacement process or use of the defined unary operator
-    does not match one of the two specified forms prior to macro replacement, the behavior is
-    undefined. After all replacements due to macro expansion and the defined unary
-    operator have been performed, all remaining identifiers (including those lexically
-    identical to keywords) are replaced with the pp-number 0, and then each preprocessing
-    token is converted into a token. The resulting tokens compose the controlling constant
-    expression which is evaluated according to the rules of 6.6. For the purposes of this
-    token conversion and evaluation, all signed integer types and all unsigned integer types
-    act as if they have the same representation as, respectively, the types intmax_t and
-    uintmax_t defined in the header <stdint.h>.165) This includes interpreting
-    character constants, which may involve converting escape sequences into execution
-    character set members. Whether the numeric value for these character constants matches
-    the value obtained when an identical character constant occurs in an expression (other
-    than within a #if or #elif directive) is implementation-defined.166) Also, whether a
-    single-character character constant may have a negative value is implementation-defined.
-
-
-
-
-    165) Thus, on an implementation where INT_MAX is 0x7FFF and UINT_MAX is 0xFFFF, the constant
-         0x8000 is signed and positive within a #if expression even though it would be unsigned in
-         translation phase 7.
-    166) Thus, the constant expression in the following #if directive and if statement is not guaranteed to
-         evaluate to the same value in these two contexts.
-            #if 'z' - 'a' == 25
-            if ('z' - 'a' == 25)
-
-
-[page 161] (Contents)
-
-5   Preprocessing directives of the forms
-       # ifdef identifier new-line groupopt
-       # ifndef identifier new-line groupopt
-    check whether the identifier is or is not currently defined as a macro name. Their
-    conditions are equivalent to #if defined identifier and #if !defined identifier
-    respectively.
-6   Each directive's condition is checked in order. If it evaluates to false (zero), the group
-    that it controls is skipped: directives are processed only through the name that determines
-    the directive in order to keep track of the level of nested conditionals; the rest of the
-    directives' preprocessing tokens are ignored, as are the other preprocessing tokens in the
-    group. Only the first group whose control condition evaluates to true (nonzero) is
-    processed. If none of the conditions evaluates to true, and there is a #else directive, the
-    group controlled by the #else is processed; lacking a #else directive, all the groups
-    until the #endif are skipped.167)
-    Forward references: macro replacement (6.10.3), source file inclusion (6.10.2), largest
-    integer types (7.20.1.5).
-    6.10.2 Source file inclusion
-    Constraints
-1   A #include directive shall identify a header or source file that can be processed by the
-    implementation.
-    Semantics
-2   A preprocessing directive of the form
-       # include <h-char-sequence> new-line
-    searches a sequence of implementation-defined places for a header identified uniquely by
-    the specified sequence between the < and > delimiters, and causes the replacement of that
-    directive by the entire contents of the header. How the places are specified or the header
-    identified is implementation-defined.
-3   A preprocessing directive of the form
-       # include "q-char-sequence" new-line
-    causes the replacement of that directive by the entire contents of the source file identified
-    by the specified sequence between the " delimiters. The named source file is searched
-
-
-    167) As indicated by the syntax, a preprocessing token shall not follow a #else or #endif directive
-         before the terminating new-line character. However, comments may appear anywhere in a source file,
-         including within a preprocessing directive.
-
-[page 162] (Contents)
-
-    for in an implementation-defined manner. If this search is not supported, or if the search
-    fails, the directive is reprocessed as if it read
-       # include <h-char-sequence> new-line
-    with the identical contained sequence (including > characters, if any) from the original
-    directive.
-4   A preprocessing directive of the form
-       # include pp-tokens new-line
-    (that does not match one of the two previous forms) is permitted. The preprocessing
-    tokens after include in the directive are processed just as in normal text. (Each
-    identifier currently defined as a macro name is replaced by its replacement list of
-    preprocessing tokens.) The directive resulting after all replacements shall match one of
-    the two previous forms.168) The method by which a sequence of preprocessing tokens
-    between a < and a > preprocessing token pair or a pair of " characters is combined into a
-    single header name preprocessing token is implementation-defined.
-5   The implementation shall provide unique mappings for sequences consisting of one or
-    more nondigits or digits (6.4.2.1) followed by a period (.) and a single nondigit. The
-    first character shall not be a digit. The implementation may ignore distinctions of
-    alphabetical case and restrict the mapping to eight significant characters before the
-    period.
-6   A #include preprocessing directive may appear in a source file that has been read
-    because of a #include directive in another file, up to an implementation-defined
-    nesting limit (see 5.2.4.1).
-7   EXAMPLE 1       The most common uses of #include preprocessing directives are as in the following:
-              #include <stdio.h>
-              #include "myprog.h"
-
-
-
-
-    168) Note that adjacent string literals are not concatenated into a single string literal (see the translation
-         phases in 5.1.1.2); thus, an expansion that results in two string literals is an invalid directive.
-
-[page 163] (Contents)
-
-8   EXAMPLE 2     This illustrates macro-replaced #include directives:
-           #if VERSION == 1
-                 #define INCFILE            "vers1.h"
-           #elif VERSION == 2
-                 #define INCFILE            "vers2.h"        // and so on
-           #else
-                  #define INCFILE           "versN.h"
-           #endif
-           #include INCFILE
-
-    Forward references: macro replacement (6.10.3).
-    6.10.3 Macro replacement
-    Constraints
-1   Two replacement lists are identical if and only if the preprocessing tokens in both have
-    the same number, ordering, spelling, and white-space separation, where all white-space
-    separations are considered identical.
-2   An identifier currently defined as an object-like macro shall not be redefined by another
-    #define preprocessing directive unless the second definition is an object-like macro
-    definition and the two replacement lists are identical. Likewise, an identifier currently
-    defined as a function-like macro shall not be redefined by another #define
-    preprocessing directive unless the second definition is a function-like macro definition
-    that has the same number and spelling of parameters, and the two replacement lists are
-    identical.
-3   There shall be white-space between the identifier and the replacement list in the definition
-    of an object-like macro.
-4   If the identifier-list in the macro definition does not end with an ellipsis, the number of
-    arguments (including those arguments consisting of no preprocessing tokens) in an
-    invocation of a function-like macro shall equal the number of parameters in the macro
-    definition. Otherwise, there shall be more arguments in the invocation than there are
-    parameters in the macro definition (excluding the ...). There shall exist a )
-    preprocessing token that terminates the invocation.
-5   The identifier __VA_ARGS__ shall occur only in the replacement-list of a function-like
-    macro that uses the ellipsis notation in the parameters.
-6   A parameter identifier in a function-like macro shall be uniquely declared within its
-    scope.
-    Semantics
-7   The identifier immediately following the define is called the macro name. There is one
-    name space for macro names. Any white-space characters preceding or following the
-    replacement list of preprocessing tokens are not considered part of the replacement list
-
-[page 164] (Contents)
-
-     for either form of macro.
-8    If a # preprocessing token, followed by an identifier, occurs lexically at the point at which
-     a preprocessing directive could begin, the identifier is not subject to macro replacement.
-9    A preprocessing directive of the form
-        # define identifier replacement-list new-line
-     defines an object-like macro that causes each subsequent instance of the macro name169)
-     to be replaced by the replacement list of preprocessing tokens that constitute the
-     remainder of the directive. The replacement list is then rescanned for more macro names
-     as specified below.
-10   A preprocessing directive of the form
-        # define identifier lparen identifier-listopt ) replacement-list new-line
-        # define identifier lparen ... ) replacement-list new-line
-        # define identifier lparen identifier-list , ... ) replacement-list new-line
-     defines a function-like macro with parameters, whose use is similar syntactically to a
-     function call. The parameters are specified by the optional list of identifiers, whose scope
-     extends from their declaration in the identifier list until the new-line character that
-     terminates the #define preprocessing directive. Each subsequent instance of the
-     function-like macro name followed by a ( as the next preprocessing token introduces the
-     sequence of preprocessing tokens that is replaced by the replacement list in the definition
-     (an invocation of the macro). The replaced sequence of preprocessing tokens is
-     terminated by the matching ) preprocessing token, skipping intervening matched pairs of
-     left and right parenthesis preprocessing tokens. Within the sequence of preprocessing
-     tokens making up an invocation of a function-like macro, new-line is considered a normal
-     white-space character.
-11   The sequence of preprocessing tokens bounded by the outside-most matching parentheses
-     forms the list of arguments for the function-like macro. The individual arguments within
-     the list are separated by comma preprocessing tokens, but comma preprocessing tokens
-     between matching inner parentheses do not separate arguments. If there are sequences of
-     preprocessing tokens within the list of arguments that would otherwise act as
-     preprocessing directives,170) the behavior is undefined.
-12   If there is a ... in the identifier-list in the macro definition, then the trailing arguments,
-     including any separating comma preprocessing tokens, are merged to form a single item:
-
-
-     169) Since, by macro-replacement time, all character constants and string literals are preprocessing tokens,
-          not sequences possibly containing identifier-like subsequences (see 5.1.1.2, translation phases), they
-          are never scanned for macro names or parameters.
-     170) Despite the name, a non-directive is a preprocessing directive.
-
-[page 165] (Contents)
-
-    the variable arguments. The number of arguments so combined is such that, following
-    merger, the number of arguments is one more than the number of parameters in the macro
-    definition (excluding the ...).
-    6.10.3.1 Argument substitution
-1   After the arguments for the invocation of a function-like macro have been identified,
-    argument substitution takes place. A parameter in the replacement list, unless preceded
-    by a # or ## preprocessing token or followed by a ## preprocessing token (see below), is
-    replaced by the corresponding argument after all macros contained therein have been
-    expanded. Before being substituted, each argument's preprocessing tokens are
-    completely macro replaced as if they formed the rest of the preprocessing file; no other
-    preprocessing tokens are available.
-2   An identifier __VA_ARGS__ that occurs in the replacement list shall be treated as if it
-    were a parameter, and the variable arguments shall form the preprocessing tokens used to
-    replace it.
-    6.10.3.2 The # operator
-    Constraints
-1   Each # preprocessing token in the replacement list for a function-like macro shall be
-    followed by a parameter as the next preprocessing token in the replacement list.
-    Semantics
-2   If, in the replacement list, a parameter is immediately preceded by a # preprocessing
-    token, both are replaced by a single character string literal preprocessing token that
-    contains the spelling of the preprocessing token sequence for the corresponding
-    argument. Each occurrence of white space between the argument's preprocessing tokens
-    becomes a single space character in the character string literal. White space before the
-    first preprocessing token and after the last preprocessing token composing the argument
-    is deleted. Otherwise, the original spelling of each preprocessing token in the argument
-    is retained in the character string literal, except for special handling for producing the
-    spelling of string literals and character constants: a \ character is inserted before each "
-    and \ character of a character constant or string literal (including the delimiting "
-    characters), except that it is implementation-defined whether a \ character is inserted
-    before the \ character beginning a universal character name. If the replacement that
-    results is not a valid character string literal, the behavior is undefined. The character
-    string literal corresponding to an empty argument is "". The order of evaluation of # and
-    ## operators is unspecified.
-
-
-
-
-[page 166] (Contents)
-
-    6.10.3.3 The ## operator
-    Constraints
-1   A ## preprocessing token shall not occur at the beginning or at the end of a replacement
-    list for either form of macro definition.
-    Semantics
-2   If, in the replacement list of a function-like macro, a parameter is immediately preceded
-    or followed by a ## preprocessing token, the parameter is replaced by the corresponding
-    argument's preprocessing token sequence; however, if an argument consists of no
-    preprocessing tokens, the parameter is replaced by a placemarker preprocessing token
-    instead.171)
-3   For both object-like and function-like macro invocations, before the replacement list is
-    reexamined for more macro names to replace, each instance of a ## preprocessing token
-    in the replacement list (not from an argument) is deleted and the preceding preprocessing
-    token is concatenated with the following preprocessing token. Placemarker
-    preprocessing tokens are handled specially: concatenation of two placemarkers results in
-    a single placemarker preprocessing token, and concatenation of a placemarker with a
-    non-placemarker preprocessing token results in the non-placemarker preprocessing token.
-    If the result is not a valid preprocessing token, the behavior is undefined. The resulting
-    token is available for further macro replacement. The order of evaluation of ## operators
-    is unspecified.
-4   EXAMPLE       In the following fragment:
-            #define     hash_hash # ## #
-            #define     mkstr(a) # a
-            #define     in_between(a) mkstr(a)
-            #define     join(c, d) in_between(c hash_hash d)
-            char p[] = join(x, y); // equivalent to
-                                   // char p[] = "x ## y";
-    The expansion produces, at various stages:
-            join(x, y)
-            in_between(x hash_hash y)
-            in_between(x ## y)
-            mkstr(x ## y)
-            "x ## y"
-    In other words, expanding hash_hash produces a new token, consisting of two adjacent sharp signs, but
-    this new token is not the ## operator.
-
-
-    171) Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
-         exist only within translation phase 4.
-
-[page 167] (Contents)
-
-    6.10.3.4 Rescanning and further replacement
-1   After all parameters in the replacement list have been substituted and # and ##
-    processing has taken place, all placemarker preprocessing tokens are removed. The
-    resulting preprocessing token sequence is then rescanned, along with all subsequent
-    preprocessing tokens of the source file, for more macro names to replace.
-2   If the name of the macro being replaced is found during this scan of the replacement list
-    (not including the rest of the source file's preprocessing tokens), it is not replaced.
-    Furthermore, if any nested replacements encounter the name of the macro being replaced,
-    it is not replaced. These nonreplaced macro name preprocessing tokens are no longer
-    available for further replacement even if they are later (re)examined in contexts in which
-    that macro name preprocessing token would otherwise have been replaced.
-3   The resulting completely macro-replaced preprocessing token sequence is not processed
-    as a preprocessing directive even if it resembles one, but all pragma unary operator
-    expressions within it are then processed as specified in 6.10.9 below.
-    6.10.3.5 Scope of macro definitions
-1   A macro definition lasts (independent of block structure) until a corresponding #undef
-    directive is encountered or (if none is encountered) until the end of the preprocessing
-    translation unit. Macro definitions have no significance after translation phase 4.
-2   A preprocessing directive of the form
-       # undef identifier new-line
-    causes the specified identifier no longer to be defined as a macro name. It is ignored if
-    the specified identifier is not currently defined as a macro name.
-3   EXAMPLE 1      The simplest use of this facility is to define a ''manifest constant'', as in
-            #define TABSIZE 100
-            int table[TABSIZE];
-
-4   EXAMPLE 2 The following defines a function-like macro whose value is the maximum of its arguments.
-    It has the advantages of working for any compatible types of the arguments and of generating in-line code
-    without the overhead of function calling. It has the disadvantages of evaluating one or the other of its
-    arguments a second time (including side effects) and generating more code than a function if invoked
-    several times. It also cannot have its address taken, as it has none.
-            #define max(a, b) ((a) > (b) ? (a) : (b))
-    The parentheses ensure that the arguments and the resulting expression are bound properly.
-
-
-
-
-[page 168] (Contents)
-
-5   EXAMPLE 3     To illustrate the rules for redefinition and reexamination, the sequence
-             #define   x         3
-             #define   f(a)      f(x * (a))
-             #undef    x
-             #define   x         2
-             #define   g         f
-             #define   z         z[0]
-             #define   h         g(~
-             #define   m(a)      a(w)
-             #define   w         0,1
-             #define   t(a)      a
-             #define   p()       int
-             #define   q(x)      x
-             #define   r(x,y)    x ## y
-             #define   str(x)    # x
-             f(y+1) + f(f(z)) % t(t(g)(0) + t)(1);
-             g(x+(3,4)-w) | h 5) & m
-                   (f)^m(m);
-             p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };
-             char c[2][6] = { str(hello), str() };
-    results in
-             f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1);
-             f(2 * (2+(3,4)-0,1)) | f(2 * (~ 5)) & f(2 * (0,1))^m(0,1);
-             int i[] = { 1, 23, 4, 5, };
-             char c[2][6] = { "hello", "" };
-
-6   EXAMPLE 4     To illustrate the rules for creating character string literals and concatenating tokens, the
-    sequence
-             #define str(s)      # s
-             #define xstr(s)     str(s)
-             #define debug(s, t) printf("x" # s "= %d, x" # t "= %s", \
-                                     x ## s, x ## t)
-             #define INCFILE(n) vers ## n
-             #define glue(a, b) a ## b
-             #define xglue(a, b) glue(a, b)
-             #define HIGHLOW     "hello"
-             #define LOW         LOW ", world"
-             debug(1, 2);
-             fputs(str(strncmp("abc\0d", "abc", '\4') // this goes away
-                   == 0) str(: @\n), s);
-             #include xstr(INCFILE(2).h)
-             glue(HIGH, LOW);
-             xglue(HIGH, LOW)
-    results in
-
-
-
-
-[page 169] (Contents)
-
-             printf("x" "1" "= %d, x" "2" "= %s", x1, x2);
-             fputs(
-               "strncmp(\"abc\\0d\", \"abc\", '\\4') == 0" ": @\n",
-               s);
-             #include "vers2.h"    (after macro replacement, before file access)
-             "hello";
-             "hello" ", world"
-    or, after concatenation of the character string literals,
-             printf("x1= %d, x2= %s", x1, x2);
-             fputs(
-               "strncmp(\"abc\\0d\", \"abc\", '\\4') == 0: @\n",
-               s);
-             #include "vers2.h"    (after macro replacement, before file access)
-             "hello";
-             "hello, world"
-    Space around the # and ## tokens in the macro definition is optional.
-
-7   EXAMPLE 5        To illustrate the rules for placemarker preprocessing tokens, the sequence
-             #define t(x,y,z) x ## y ## z
-             int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,),
-                        t(10,,), t(,11,), t(,,12), t(,,) };
-    results in
-             int j[] = { 123, 45, 67, 89,
-                         10, 11, 12, };
-
-8   EXAMPLE 6        To demonstrate the redefinition rules, the following sequence is valid.
-             #define      OBJ_LIKE      (1-1)
-             #define      OBJ_LIKE      /* white space */ (1-1) /* other */
-             #define      FUNC_LIKE(a)   ( a )
-             #define      FUNC_LIKE( a )( /* note the white space */ \
-                                          a /* other stuff on this line
-                                              */ )
-    But the following redefinitions are invalid:
-             #define      OBJ_LIKE    (0)     // different token sequence
-             #define      OBJ_LIKE    (1 - 1) // different white space
-             #define      FUNC_LIKE(b) ( a ) // different parameter usage
-             #define      FUNC_LIKE(b) ( b ) // different parameter spelling
-
-9   EXAMPLE 7        Finally, to show the variable argument list macro facilities:
-             #define debug(...)       fprintf(stderr, __VA_ARGS__)
-             #define showlist(...)    puts(#__VA_ARGS__)
-             #define report(test, ...) ((test)?puts(#test):\
-                         printf(__VA_ARGS__))
-             debug("Flag");
-             debug("X = %d\n", x);
-             showlist(The first, second, and third items.);
-             report(x>y, "x is %d but y is %d", x, y);
-
-
-[page 170] (Contents)
-
-    results in
-              fprintf(stderr, "Flag" );
-              fprintf(stderr, "X = %d\n", x );
-              puts( "The first, second, and third items." );
-              ((x>y)?puts("x>y"):
-                          printf("x is %d but y is %d", x, y));
-
-    6.10.4 Line control
-    Constraints
-1   The string literal of a #line directive, if present, shall be a character string literal.
-    Semantics
-2   The line number of the current source line is one greater than the number of new-line
-    characters read or introduced in translation phase 1 (5.1.1.2) while processing the source
-    file to the current token.
-3   A preprocessing directive of the form
-       # line digit-sequence new-line
-    causes the implementation to behave as if the following sequence of source lines begins
-    with a source line that has a line number as specified by the digit sequence (interpreted as
-    a decimal integer). The digit sequence shall not specify zero, nor a number greater than
-    2147483647.
-4   A preprocessing directive of the form
-       # line digit-sequence "s-char-sequenceopt" new-line
-    sets the presumed line number similarly and changes the presumed name of the source
-    file to be the contents of the character string literal.
-5   A preprocessing directive of the form
-       # line pp-tokens new-line
-    (that does not match one of the two previous forms) is permitted. The preprocessing
-    tokens after line on the directive are processed just as in normal text (each identifier
-    currently defined as a macro name is replaced by its replacement list of preprocessing
-    tokens). The directive resulting after all replacements shall match one of the two
-    previous forms and is then processed as appropriate.
-
-
-
-
-[page 171] (Contents)
-
-    6.10.5 Error directive
-    Semantics
-1   A preprocessing directive of the form
-       # error pp-tokensopt new-line
-    causes the implementation to produce a diagnostic message that includes the specified
-    sequence of preprocessing tokens.
-    6.10.6 Pragma directive
-    Semantics
-1   A preprocessing directive of the form
-       # pragma pp-tokensopt new-line
-    where the preprocessing token STDC does not immediately follow pragma in the
-    directive (prior to any macro replacement)172) causes the implementation to behave in an
-    implementation-defined manner. The behavior might cause translation to fail or cause the
-    translator or the resulting program to behave in a non-conforming manner. Any such
-    pragma that is not recognized by the implementation is ignored.
-2   If the preprocessing token STDC does immediately follow pragma in the directive (prior
-    to any macro replacement), then no macro replacement is performed on the directive, and
-    the directive shall have one of the following forms173) whose meanings are described
-    elsewhere:
-       #pragma STDC FP_CONTRACT on-off-switch
-       #pragma STDC FENV_ACCESS on-off-switch
-       #pragma STDC CX_LIMITED_RANGE on-off-switch
-       on-off-switch: one of
-                   ON     OFF           DEFAULT
-    Forward references: the FP_CONTRACT pragma (7.12.2), the FENV_ACCESS pragma
-    (7.6.1), the CX_LIMITED_RANGE pragma (7.3.4).
-
-
-
-
-    172) An implementation is not required to perform macro replacement in pragmas, but it is permitted
-         except for in standard pragmas (where STDC immediately follows pragma). If the result of macro
-         replacement in a non-standard pragma has the same form as a standard pragma, the behavior is still
-         implementation-defined; an implementation is permitted to behave as if it were the standard pragma,
-         but is not required to.
-    173) See ''future language directions'' (6.11.8).
-
-[page 172] (Contents)
-
-    6.10.7 Null directive
-    Semantics
-1   A preprocessing directive of the form
-       # new-line
-    has no effect.
-    6.10.8 Predefined macro names
-1   The values of the predefined macros listed in the following subclauses174) (except for
-    __FILE__ and __LINE__) remain constant throughout the translation unit.
-2   None of these macro names, nor the identifier defined, shall be the subject of a
-    #define or a #undef preprocessing directive. Any other predefined macro names
-    shall begin with a leading underscore followed by an uppercase letter or a second
-    underscore.
-3   The implementation shall not predefine the macro __cplusplus, nor shall it define it
-    in any standard header.
-    Forward references: standard headers (7.1.2).
-    6.10.8.1 Mandatory macros
-1   The following macro names shall be defined by the implementation:
-    __DATE__ The date of translation of the preprocessing translation unit: a character
-               string literal of the form "Mmm dd yyyy", where the names of the
-               months are the same as those generated by the asctime function, and the
-               first character of dd is a space character if the value is less than 10. If the
-               date of translation is not available, an implementation-defined valid date
-               shall be supplied.
-    __FILE__ The presumed name of the current source file (a character string literal).175)
-    __LINE__ The presumed line number (within the current source file) of the current
-               source line (an integer constant).175)
-    __STDC__ The integer constant 1, intended to indicate a conforming implementation.
-    __STDC_HOSTED__ The integer constant 1 if the implementation is a hosted
-              implementation or the integer constant 0 if it is not.
-
-
-
-
-    174) See ''future language directions'' (6.11.9).
-    175) The presumed source file name and line number can be changed by the #line directive.
-
-[page 173] (Contents)
-
-    __STDC_VERSION__ The integer constant 201ymmL.176)
-    __TIME__ The time of translation of the preprocessing translation unit: a character
-               string literal of the form "hh:mm:ss" as in the time generated by the
-               asctime function. If the time of translation is not available, an
-               implementation-defined valid time shall be supplied.
-    Forward references: the asctime function (7.26.3.1).
-    6.10.8.2 Environment macros
-1   The following macro names are conditionally defined by the implementation:
-    __STDC_ISO_10646__ An integer constant of the form yyyymmL (for example,
-              199712L). If this symbol is defined, then every character in the Unicode
-              required set, when stored in an object of type wchar_t, has the same
-              value as the short identifier of that character. The Unicode required set
-              consists of all the characters that are defined by ISO/IEC 10646, along with
-              all amendments and technical corrigenda, as of the specified year and
-              month. If some other encoding is used, the macro shall not be defined and
-              the actual encoding used is implementation-defined.
-    __STDC_MB_MIGHT_NEQ_WC__ The integer constant 1, intended to indicate that, in
-              the encoding for wchar_t, a member of the basic character set need not
-              have a code value equal to its value when used as the lone character in an
-              integer character constant.
-    __STDC_UTF_16__ The integer constant 1, intended to indicate that values of type
-              char16_t are UTF-16 encoded. If some other encoding is used, the
-              macro shall not be defined and the actual encoding used is implementation-
-              defined.
-    __STDC_UTF_32__ The integer constant 1, intended to indicate that values of type
-              char32_t are UTF-32 encoded. If some other encoding is used, the
-              macro shall not be defined and the actual encoding used is implementation-
-              defined.
-    Forward references: common definitions (7.19), unicode utilities (7.27).
-
-
-
-
-    176) This macro was not specified in ISO/IEC 9899:1990 and was specified as 199409L in
-         ISO/IEC 9899/AMD1:1995 and as 199901L in ISO/IEC 9899:1999. The intention is that this will
-         remain an integer constant of type long int that is increased with each revision of this International
-         Standard.
-
-[page 174] (Contents)
-
-    6.10.8.3 Conditional feature macros
-1   The following macro names are conditionally defined by the implementation:
-    __STDC_ANALYZABLE__ The integer constant 1, intended to indicate conformance to
-              the specifications in annex L (Analyzability).
-    __STDC_IEC_559__ The integer constant 1, intended to indicate conformance to the
-              specifications in annex F (IEC 60559 floating-point arithmetic).
-    __STDC_IEC_559_COMPLEX__ The integer constant 1, intended to indicate
-              adherence to the specifications in informative annex G (IEC 60559
-              compatible complex arithmetic).
-    __STDC_LIB_EXT1__ The integer constant 201ymmL, intended to indicate support
-              for the extensions defined in annex K (Bounds-checking interfaces).177)
-    __STDC_NO_COMPLEX__ The integer constant 1, intended to indicate that the
-              implementation does not support complex types or the <complex.h>
-              header.
-    __STDC_NO_THREADS__ The integer constant 1, intended to indicate that the
-              implementation does not support atomic types (including the _Atomic
-              type qualifier and the <stdatomic.h> header) or the <threads.h>
-              header.
-    __STDC_NO_VLA__ The integer constant 1, intended to indicate that the
-              implementation does not support variable length arrays or variably
-              modified types.
-    6.10.9 Pragma operator
-    Semantics
-1   A unary operator expression of the form:
-       _Pragma ( string-literal )
-    is processed as follows: The string literal is destringized by deleting the L prefix, if
-    present, deleting the leading and trailing double-quotes, replacing each escape sequence
-    \" by a double-quote, and replacing each escape sequence \\ by a single backslash. The
-    resulting sequence of characters is processed through translation phase 3 to produce
-    preprocessing tokens that are executed as if they were the pp-tokens in a pragma
-    directive. The original four preprocessing tokens in the unary operator expression are
-    removed.
-
-
-    177) The intention is that this will remain an integer constant of type long int that is increased with
-         each revision of this International Standard.
-
-[page 175] (Contents)
-
-2   EXAMPLE       A directive of the form:
-             #pragma listing on "..\listing.dir"
-    can also be expressed as:
-             _Pragma ( "listing on \"..\\listing.dir\"" )
-    The latter form is processed in the same way whether it appears literally as shown, or results from macro
-    replacement, as in:
-             #define LISTING(x) PRAGMA(listing on #x)
-             #define PRAGMA(x) _Pragma(#x)
-             LISTING ( ..\listing.dir )
-
-
-
-
-[page 176] (Contents)
-
-    6.11 Future language directions
-    6.11.1 Floating types
-1   Future standardization may include additional floating-point types, including those with
-    greater range, precision, or both than long double.
-    6.11.2 Linkages of identifiers
-1   Declaring an identifier with internal linkage at file scope without the static storage-
-    class specifier is an obsolescent feature.
-    6.11.3 External names
-1   Restriction of the significance of an external name to fewer than 255 characters
-    (considering each universal character name or extended source character as a single
-    character) is an obsolescent feature that is a concession to existing implementations.
-    6.11.4 Character escape sequences
-1   Lowercase letters as escape sequences are reserved for future standardization. Other
-    characters may be used in extensions.
-    6.11.5 Storage-class specifiers
-1   The placement of a storage-class specifier other than at the beginning of the declaration
-    specifiers in a declaration is an obsolescent feature.
-    6.11.6 Function declarators
-1   The use of function declarators with empty parentheses (not prototype-format parameter
-    type declarators) is an obsolescent feature.
-    6.11.7 Function definitions
-1   The use of function definitions with separate parameter identifier and declaration lists
-    (not prototype-format parameter type and identifier declarators) is an obsolescent feature.
-    6.11.8 Pragma directives
-1   Pragmas whose first preprocessing token is STDC are reserved for future standardization.
-    6.11.9 Predefined macro names
-1   Macro names beginning with __STDC_ are reserved for future standardization.
-
-
-
-
-[page 177] (Contents)
-
-
-    7. Library
-    7.1 Introduction
-    7.1.1 Definitions of terms
-1   A string is a contiguous sequence of characters terminated by and including the first null
-    character. The term multibyte string is sometimes used instead to emphasize special
-    processing given to multibyte characters contained in the string or to avoid confusion
-    with a wide string. A pointer to a string is a pointer to its initial (lowest addressed)
-    character. The length of a string is the number of bytes preceding the null character and
-    the value of a string is the sequence of the values of the contained characters, in order.
-2   The decimal-point character is the character used by functions that convert floating-point
-    numbers to or from character sequences to denote the beginning of the fractional part of
-    such character sequences.178) It is represented in the text and examples by a period, but
-    may be changed by the setlocale function.
-3   A null wide character is a wide character with code value zero.
-4   A wide string is a contiguous sequence of wide characters terminated by and including
-    the first null wide character. A pointer to a wide string is a pointer to its initial (lowest
-    addressed) wide character. The length of a wide string is the number of wide characters
-    preceding the null wide character and the value of a wide string is the sequence of code
-    values of the contained wide characters, in order.
-5   A shift sequence is a contiguous sequence of bytes within a multibyte string that
-    (potentially) causes a change in shift state (see 5.2.1.2). A shift sequence shall not have a
-    corresponding wide character; it is instead taken to be an adjunct to an adjacent multibyte
-    character.179)
-    Forward references: character handling (7.4), the setlocale function (7.11.1.1).
-
-
-
-
-    178) The functions that make use of the decimal-point character are the numeric conversion functions
-         (7.22.1, 7.28.4.1) and the formatted input/output functions (7.21.6, 7.28.2).
-    179) For state-dependent encodings, the values for MB_CUR_MAX and MB_LEN_MAX shall thus be large
-         enough to count all the bytes in any complete multibyte character plus at least one adjacent shift
-         sequence of maximum length. Whether these counts provide for more than one shift sequence is the
-         implementation's choice.
-
-[page 178] (Contents)
-
-    7.1.2 Standard headers
-1   Each library function is declared, with a type that includes a prototype, in a header,180)
-    whose contents are made available by the #include preprocessing directive. The
-    header declares a set of related functions, plus any necessary types and additional macros
-    needed to facilitate their use. Declarations of types described in this clause shall not
-    include type qualifiers, unless explicitly stated otherwise.
-2   The standard headers are181)
-           <assert.h>             <iso646.h>              <stdarg.h>              <string.h>
-           <complex.h>            <limits.h>              <stdatomic.h>           <tgmath.h>
-           <ctype.h>              <locale.h>              <stdbool.h>             <threads.h>
-           <errno.h>              <math.h>                <stddef.h>              <time.h>
-           <fenv.h>               <setjmp.h>              <stdint.h>              <uchar.h>
-           <float.h>              <signal.h>              <stdio.h>               <wchar.h>
-           <inttypes.h>           <stdalign.h>            <stdlib.h>              <wctype.h>
-3   If a file with the same name as one of the above < and > delimited sequences, not
-    provided as part of the implementation, is placed in any of the standard places that are
-    searched for included source files, the behavior is undefined.
-4   Standard headers may be included in any order; each may be included more than once in
-    a given scope, with no effect different from being included only once, except that the
-    effect of including <assert.h> depends on the definition of NDEBUG (see 7.2). If
-    used, a header shall be included outside of any external declaration or definition, and it
-    shall first be included before the first reference to any of the functions or objects it
-    declares, or to any of the types or macros it defines. However, if an identifier is declared
-    or defined in more than one header, the second and subsequent associated headers may be
-    included after the initial reference to the identifier. The program shall not have any
-    macros with names lexically identical to keywords currently defined prior to the
-    inclusion.
-5   Any definition of an object-like macro described in this clause shall expand to code that is
-    fully protected by parentheses where necessary, so that it groups in an arbitrary
-    expression as if it were a single identifier.
-6   Any declaration of a library function shall have external linkage.
-
-
-
-
-    180) A header is not necessarily a source file, nor are the < and > delimited sequences in header names
-         necessarily valid source file names.
-    181) The headers <complex.h>, <stdatomic.h>, and <threads.h> are conditional features that
-         implementations need not support; see 6.10.8.3.
-
-[page 179] (Contents)
-
-7   A summary of the contents of the standard headers is given in annex B.
-    Forward references: diagnostics (7.2).
-    7.1.3 Reserved identifiers
-1   Each header declares or defines all identifiers listed in its associated subclause, and
-    optionally declares or defines identifiers listed in its associated future library directions
-    subclause and identifiers which are always reserved either for any use or for use as file
-    scope identifiers.
-    -- All identifiers that begin with an underscore and either an uppercase letter or another
-      underscore are always reserved for any use.
-    -- All identifiers that begin with an underscore are always reserved for use as identifiers
-      with file scope in both the ordinary and tag name spaces.
-    -- Each macro name in any of the following subclauses (including the future library
-      directions) is reserved for use as specified if any of its associated headers is included;
-      unless explicitly stated otherwise (see 7.1.4).
-    -- All identifiers with external linkage in any of the following subclauses (including the
-      future library directions) and errno are always reserved for use as identifiers with
-      external linkage.182)
-    -- Each identifier with file scope listed in any of the following subclauses (including the
-      future library directions) is reserved for use as a macro name and as an identifier with
-      file scope in the same name space if any of its associated headers is included.
-2   No other identifiers are reserved. If the program declares or defines an identifier in a
-    context in which it is reserved (other than as allowed by 7.1.4), or defines a reserved
-    identifier as a macro name, the behavior is undefined.
-3   If the program removes (with #undef) any macro definition of an identifier in the first
-    group listed above, the behavior is undefined.
-
-
-
-
-    182) The list of reserved identifiers with external linkage includes math_errhandling, setjmp,
-         va_copy, and va_end.
-
-[page 180] (Contents)
-
-    7.1.4 Use of library functions
-1   Each of the following statements applies unless explicitly stated otherwise in the detailed
-    descriptions that follow: If an argument to a function has an invalid value (such as a value
-    outside the domain of the function, or a pointer outside the address space of the program,
-    or a null pointer, or a pointer to non-modifiable storage when the corresponding
-    parameter is not const-qualified) or a type (after promotion) not expected by a function
-    with variable number of arguments, the behavior is undefined. If a function argument is
-    described as being an array, the pointer actually passed to the function shall have a value
-    such that all address computations and accesses to objects (that would be valid if the
-    pointer did point to the first element of such an array) are in fact valid. Any function
-    declared in a header may be additionally implemented as a function-like macro defined in
-    the header, so if a library function is declared explicitly when its header is included, one
-    of the techniques shown below can be used to ensure the declaration is not affected by
-    such a macro. Any macro definition of a function can be suppressed locally by enclosing
-    the name of the function in parentheses, because the name is then not followed by the left
-    parenthesis that indicates expansion of a macro function name. For the same syntactic
-    reason, it is permitted to take the address of a library function even if it is also defined as
-    a macro.183) The use of #undef to remove any macro definition will also ensure that an
-    actual function is referred to. Any invocation of a library function that is implemented as
-    a macro shall expand to code that evaluates each of its arguments exactly once, fully
-    protected by parentheses where necessary, so it is generally safe to use arbitrary
-    expressions as arguments.184) Likewise, those function-like macros described in the
-    following subclauses may be invoked in an expression anywhere a function with a
-    compatible return type could be called.185) All object-like macros listed as expanding to
-
-
-    183) This means that an implementation shall provide an actual function for each library function, even if it
-         also provides a macro for that function.
-    184) Such macros might not contain the sequence points that the corresponding function calls do.
-    185) Because external identifiers and some macro names beginning with an underscore are reserved,
-         implementations may provide special semantics for such names. For example, the identifier
-         _BUILTIN_abs could be used to indicate generation of in-line code for the abs function. Thus, the
-         appropriate header could specify
-                  #define abs(x) _BUILTIN_abs(x)
-         for a compiler whose code generator will accept it.
-         In this manner, a user desiring to guarantee that a given library function such as abs will be a genuine
-         function may write
-                  #undef abs
-         whether the implementation's header provides a macro implementation of abs or a built-in
-         implementation. The prototype for the function, which precedes and is hidden by any macro
-         definition, is thereby revealed also.
-
-[page 181] (Contents)
-
-    integer constant expressions shall additionally be suitable for use in #if preprocessing
-    directives.
-2   Provided that a library function can be declared without reference to any type defined in a
-    header, it is also permissible to declare the function and use it without including its
-    associated header.
-3   There is a sequence point immediately before a library function returns.
-4   The functions in the standard library are not guaranteed to be reentrant and may modify
-    objects with static or thread storage duration.186)
-5   Unless explicitly stated otherwise in the detailed descriptions that follow, library
-    functions shall prevent data races as follows: A library function shall not directly or
-    indirectly access objects accessible by threads other than the current thread unless the
-    objects are accessed directly or indirectly via the function's arguments. A library
-    function shall not directly or indirectly modify objects accessible by threads other than
-    the current thread unless the objects are accessed directly or indirectly via the function's
-    non-const arguments.187) Implementations may share their own internal objects between
-    threads if the objects are not visible to users and are protected against data races.
-6   Unless otherwise specified, library functions shall perform all operations solely within the
-    current thread if those operations have effects that are visible to users.188)
-7   EXAMPLE        The function atoi may be used in any of several ways:
-    -- by use of its associated header (possibly generating a macro expansion)
-                 #include <stdlib.h>
-                 const char *str;
-                 /* ... */
-                 i = atoi(str);
-    -- by use of its associated header (assuredly generating a true function reference)
-
-
-
-
-    186) Thus, a signal handler cannot, in general, call standard library functions.
-    187) This means, for example, that an implementation is not permitted to use a static object for internal
-         purposes without synchronization because it could cause a data race even in programs that do not
-         explicitly share objects between threads.
-    188) This allows implementations to parallelize operations if there are no visible side effects.
-
-[page 182] (Contents)
-
-            #include <stdlib.h>
-            #undef atoi
-            const char *str;
-            /* ... */
-            i = atoi(str);
-   or
-            #include <stdlib.h>
-            const char *str;
-            /* ... */
-            i = (atoi)(str);
--- by explicit declaration
-            extern int atoi(const char *);
-            const char *str;
-            /* ... */
-            i = atoi(str);
-
-
-
-
-[page 183] (Contents)
-
-    7.2 Diagnostics <assert.h>
-1   The header <assert.h> defines the assert and static_assert macros and
-    refers to another macro,
-            NDEBUG
-    which is not defined by <assert.h>. If NDEBUG is defined as a macro name at the
-    point in the source file where <assert.h> is included, the assert macro is defined
-    simply as
-            #define assert(ignore) ((void)0)
-    The assert macro is redefined according to the current state of NDEBUG each time that
-    <assert.h> is included.
-2   The assert macro shall be implemented as a macro, not as an actual function. If the
-    macro definition is suppressed in order to access an actual function, the behavior is
-    undefined.
-3   The macro
-            static_assert
-    expands to _Static_assert.
-    7.2.1 Program diagnostics
-    7.2.1.1 The assert macro
-    Synopsis
-1           #include <assert.h>
-            void assert(scalar expression);
-    Description
-2   The assert macro puts diagnostic tests into programs; it expands to a void expression.
-    When it is executed, if expression (which shall have a scalar type) is false (that is,
-    compares equal to 0), the assert macro writes information about the particular call that
-    failed (including the text of the argument, the name of the source file, the source line
-    number, and the name of the enclosing function -- the latter are respectively the values of
-    the preprocessing macros __FILE__ and __LINE__ and of the identifier
-    __func__) on the standard error stream in an implementation-defined format.189) It
-    then calls the abort function.
-
-
-
-    189) The message written might be of the form:
-          Assertion failed: expression, function abc, file xyz, line nnn.
-
-
-[page 184] (Contents)
-
-    Returns
-3   The assert macro returns no value.
-    Forward references: the abort function (7.22.4.1).
-
-
-
-
-[page 185] (Contents)
-
-    7.3 Complex arithmetic <complex.h>
-    7.3.1 Introduction
-1   The header <complex.h> defines macros and declares functions that support complex
-    arithmetic.190)
-2   Implementations that define the macro __STDC_NO_COMPLEX__ need not provide
-    this header nor support any of its facilities.
-3   Each synopsis specifies a family of functions consisting of a principal function with one
-    or more double complex parameters and a double complex or double return
-    value; and other functions with the same name but with f and l suffixes which are
-    corresponding functions with float and long double parameters and return values.
-4   The macro
-             complex
-    expands to _Complex; the macro
-             _Complex_I
-    expands to a constant expression of type const float _Complex, with the value of
-    the imaginary unit.191)
-5   The macros
-             imaginary
-    and
-             _Imaginary_I
-    are defined if and only if the implementation supports imaginary types;192) if defined,
-    they expand to _Imaginary and a constant expression of type const float
-    _Imaginary with the value of the imaginary unit.
-6   The macro
-             I
-    expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not
-    defined, I shall expand to _Complex_I.
-7   Notwithstanding the provisions of 7.1.3, a program may undefine and perhaps then
-    redefine the macros complex, imaginary, and I.
-
-    190) See ''future library directions'' (7.30.1).
-    191) The imaginary unit is a number i such that i 2 = -1.
-    192) A specification for imaginary types is in informative annex G.
-
-[page 186] (Contents)
-
-    Forward references: IEC 60559-compatible complex arithmetic (annex G).
-    7.3.2 Conventions
-1   Values are interpreted as radians, not degrees. An implementation may set errno but is
-    not required to.
-    7.3.3 Branch cuts
-1   Some of the functions below have branch cuts, across which the function is
-    discontinuous. For implementations with a signed zero (including all IEC 60559
-    implementations) that follow the specifications of annex G, the sign of zero distinguishes
-    one side of a cut from another so the function is continuous (except for format
-    limitations) as the cut is approached from either side. For example, for the square root
-    function, which has a branch cut along the negative real axis, the top of the cut, with
-    imaginary part +0, maps to the positive imaginary axis, and the bottom of the cut, with
-    imaginary part -0, maps to the negative imaginary axis.
-2   Implementations that do not support a signed zero (see annex F) cannot distinguish the
-    sides of branch cuts. These implementations shall map a cut so the function is continuous
-    as the cut is approached coming around the finite endpoint of the cut in a counter
-    clockwise direction. (Branch cuts for the functions specified here have just one finite
-    endpoint.) For example, for the square root function, coming counter clockwise around
-    the finite endpoint of the cut along the negative real axis approaches the cut from above,
-    so the cut maps to the positive imaginary axis.
-    7.3.4 The CX_LIMITED_RANGE pragma
-    Synopsis
-1            #include <complex.h>
-             #pragma STDC CX_LIMITED_RANGE on-off-switch
-    Description
-2   The usual mathematical formulas for complex multiply, divide, and absolute value are
-    problematic because of their treatment of infinities and because of undue overflow and
-    underflow. The CX_LIMITED_RANGE pragma can be used to inform the
-    implementation that (where the state is ''on'') the usual mathematical formulas are
-    acceptable.193) The pragma can occur either outside external declarations or preceding all
-    explicit declarations and statements inside a compound statement. When outside external
-    declarations, the pragma takes effect from its occurrence until another
-    CX_LIMITED_RANGE pragma is encountered, or until the end of the translation unit.
-    When inside a compound statement, the pragma takes effect from its occurrence until
-    another CX_LIMITED_RANGE pragma is encountered (including within a nested
-    compound statement), or until the end of the compound statement; at the end of a
-    compound statement the state for the pragma is restored to its condition just before the
-
-[page 187] (Contents)
-
-    compound statement. If this pragma is used in any other context, the behavior is
-    undefined. The default state for the pragma is ''off''.
-    7.3.5 Trigonometric functions
-    7.3.5.1 The cacos functions
-    Synopsis
-1            #include <complex.h>
-             double complex cacos(double complex z);
-             float complex cacosf(float complex z);
-             long double complex cacosl(long double complex z);
-    Description
-2   The cacos functions compute the complex arc cosine of z, with branch cuts outside the
-    interval [-1, +1] along the real axis.
-    Returns
-3   The cacos functions return the complex arc cosine value, in the range of a strip
-    mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the
-    real axis.
-    7.3.5.2 The casin functions
-    Synopsis
-1            #include <complex.h>
-             double complex casin(double complex z);
-             float complex casinf(float complex z);
-             long double complex casinl(long double complex z);
-    Description
-2   The casin functions compute the complex arc sine of z, with branch cuts outside the
-    interval [-1, +1] along the real axis.
-    Returns
-3   The casin functions return the complex arc sine value, in the range of a strip
-    mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
-
-    193) The purpose of the pragma is to allow the implementation to use the formulas:
-             (x + iy) x (u + iv) = (xu - yv) + i(yu + xv)
-             (x + iy) / (u + iv) = [(xu + yv) + i(yu - xv)]/(u2 + v 2 )
-             | x + iy | = sqrt: x 2 + y 2
-                          -----
-          where the programmer can determine they are safe.
-
-[page 188] (Contents)
-
-    along the real axis.
-    7.3.5.3 The catan functions
-    Synopsis
-1           #include <complex.h>
-            double complex catan(double complex z);
-            float complex catanf(float complex z);
-            long double complex catanl(long double complex z);
-    Description
-2   The catan functions compute the complex arc tangent of z, with branch cuts outside the
-    interval [-i, +i] along the imaginary axis.
-    Returns
-3   The catan functions return the complex arc tangent value, in the range of a strip
-    mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
-    along the real axis.
-    7.3.5.4 The ccos functions
-    Synopsis
-1           #include <complex.h>
-            double complex ccos(double complex z);
-            float complex ccosf(float complex z);
-            long double complex ccosl(long double complex z);
-    Description
-2   The ccos functions compute the complex cosine of z.
-    Returns
-3   The ccos functions return the complex cosine value.
-    7.3.5.5 The csin functions
-    Synopsis
-1           #include <complex.h>
-            double complex csin(double complex z);
-            float complex csinf(float complex z);
-            long double complex csinl(long double complex z);
-    Description
-2   The csin functions compute the complex sine of z.
-
-
-
-[page 189] (Contents)
-
-    Returns
-3   The csin functions return the complex sine value.
-    7.3.5.6 The ctan functions
-    Synopsis
-1          #include <complex.h>
-           double complex ctan(double complex z);
-           float complex ctanf(float complex z);
-           long double complex ctanl(long double complex z);
-    Description
-2   The ctan functions compute the complex tangent of z.
-    Returns
-3   The ctan functions return the complex tangent value.
-    7.3.6 Hyperbolic functions
-    7.3.6.1 The cacosh functions
-    Synopsis
-1          #include <complex.h>
-           double complex cacosh(double complex z);
-           float complex cacoshf(float complex z);
-           long double complex cacoshl(long double complex z);
-    Description
-2   The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch
-    cut at values less than 1 along the real axis.
-    Returns
-3   The cacosh functions return the complex arc hyperbolic cosine value, in the range of a
-    half-strip of non-negative values along the real axis and in the interval [-ipi , +ipi ] along
-    the imaginary axis.
-    7.3.6.2 The casinh functions
-    Synopsis
-1          #include <complex.h>
-           double complex casinh(double complex z);
-           float complex casinhf(float complex z);
-           long double complex casinhl(long double complex z);
-
-
-
-[page 190] (Contents)
-
-    Description
-2   The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts
-    outside the interval [-i, +i] along the imaginary axis.
-    Returns
-3   The casinh functions return the complex arc hyperbolic sine value, in the range of a
-    strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
-    along the imaginary axis.
-    7.3.6.3 The catanh functions
-    Synopsis
-1           #include <complex.h>
-            double complex catanh(double complex z);
-            float complex catanhf(float complex z);
-            long double complex catanhl(long double complex z);
-    Description
-2   The catanh functions compute the complex arc hyperbolic tangent of z, with branch
-    cuts outside the interval [-1, +1] along the real axis.
-    Returns
-3   The catanh functions return the complex arc hyperbolic tangent value, in the range of a
-    strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
-    along the imaginary axis.
-    7.3.6.4 The ccosh functions
-    Synopsis
-1           #include <complex.h>
-            double complex ccosh(double complex z);
-            float complex ccoshf(float complex z);
-            long double complex ccoshl(long double complex z);
-    Description
-2   The ccosh functions compute the complex hyperbolic cosine of z.
-    Returns
-3   The ccosh functions return the complex hyperbolic cosine value.
-
-
-
-
-[page 191] (Contents)
-
-    7.3.6.5 The csinh functions
-    Synopsis
-1          #include <complex.h>
-           double complex csinh(double complex z);
-           float complex csinhf(float complex z);
-           long double complex csinhl(long double complex z);
-    Description
-2   The csinh functions compute the complex hyperbolic sine of z.
-    Returns
-3   The csinh functions return the complex hyperbolic sine value.
-    7.3.6.6 The ctanh functions
-    Synopsis
-1          #include <complex.h>
-           double complex ctanh(double complex z);
-           float complex ctanhf(float complex z);
-           long double complex ctanhl(long double complex z);
-    Description
-2   The ctanh functions compute the complex hyperbolic tangent of z.
-    Returns
-3   The ctanh functions return the complex hyperbolic tangent value.
-    7.3.7 Exponential and logarithmic functions
-    7.3.7.1 The cexp functions
-    Synopsis
-1          #include <complex.h>
-           double complex cexp(double complex z);
-           float complex cexpf(float complex z);
-           long double complex cexpl(long double complex z);
-    Description
-2   The cexp functions compute the complex base-e exponential of z.
-    Returns
-3   The cexp functions return the complex base-e exponential value.
-
-
-
-[page 192] (Contents)
-
-    7.3.7.2 The clog functions
-    Synopsis
-1           #include <complex.h>
-            double complex clog(double complex z);
-            float complex clogf(float complex z);
-            long double complex clogl(long double complex z);
-    Description
-2   The clog functions compute the complex natural (base-e) logarithm of z, with a branch
-    cut along the negative real axis.
-    Returns
-3   The clog functions return the complex natural logarithm value, in the range of a strip
-    mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the
-    imaginary axis.
-    7.3.8 Power and absolute-value functions
-    7.3.8.1 The cabs functions
-    Synopsis
-1           #include <complex.h>
-            double cabs(double complex z);
-            float cabsf(float complex z);
-            long double cabsl(long double complex z);
-    Description
-2   The cabs functions compute the complex absolute value (also called norm, modulus, or
-    magnitude) of z.
-    Returns
-3   The cabs functions return the complex absolute value.
-    7.3.8.2 The cpow functions
-    Synopsis
-1           #include <complex.h>
-            double complex cpow(double complex x, double complex y);
-            float complex cpowf(float complex x, float complex y);
-            long double complex cpowl(long double complex x,
-                 long double complex y);
-
-
-
-
-[page 193] (Contents)
-
-    Description
-2   The cpow functions compute the complex power function xy , with a branch cut for the
-    first parameter along the negative real axis.
-    Returns
-3   The cpow functions return the complex power function value.
-    7.3.8.3 The csqrt functions
-    Synopsis
-1          #include <complex.h>
-           double complex csqrt(double complex z);
-           float complex csqrtf(float complex z);
-           long double complex csqrtl(long double complex z);
-    Description
-2   The csqrt functions compute the complex square root of z, with a branch cut along the
-    negative real axis.
-    Returns
-3   The csqrt functions return the complex square root value, in the range of the right half-
-    plane (including the imaginary axis).
-    7.3.9 Manipulation functions
-    7.3.9.1 The carg functions
-    Synopsis
-1          #include <complex.h>
-           double carg(double complex z);
-           float cargf(float complex z);
-           long double cargl(long double complex z);
-    Description
-2   The carg functions compute the argument (also called phase angle) of z, with a branch
-    cut along the negative real axis.
-    Returns
-3   The carg functions return the value of the argument in the interval [-pi , +pi ].
-
-
-
-
-[page 194] (Contents)
-
-    7.3.9.2 The cimag functions
-    Synopsis
-1           #include <complex.h>
-            double cimag(double complex z);
-            float cimagf(float complex z);
-            long double cimagl(long double complex z);
-    Description
-2   The cimag functions compute the imaginary part of z.194)
-    Returns
-3   The cimag functions return the imaginary part value (as a real).
-    7.3.9.3 The CMPLX macros
-    Synopsis
-1           #include <complex.h>
-            double complex CMPLX(double x, double y);
-            float complex CMPLXF(float x, float y);
-            long double complex CMPLXL(long double x, long double y);
-    Description
-2   The CMPLX macros expand to an expression of the specified complex type, with the real
-    part having the (converted) value of x and the imaginary part having the (converted)
-    value of y.
-    Recommended practice
-3   The resulting expression should be suitable for use as an initializer for an object with
-    static or thread storage duration, provided both arguments are likewise suitable.
-    Returns
-4   The CMPLX macros return the complex value x + i y.
-5   NOTE    These macros act as if the implementation supported imaginary types and the definitions were:
-         #define CMPLX(x, y)  ((double complex)((double)(x) + \
-                                       _Imaginary_I * (double)(y)))
-         #define CMPLXF(x, y) ((float complex)((float)(x) + \
-                                       _Imaginary_I * (float)(y)))
-         #define CMPLXL(x, y) ((long double complex)((long double)(x) + \
-                                       _Imaginary_I * (long double)(y)))
-
-
-
-
-    194) For a variable z of complex type, z == creal(z) + cimag(z)*I.
-
-[page 195] (Contents)
-
-    7.3.9.4 The conj functions
-    Synopsis
-1          #include <complex.h>
-           double complex conj(double complex z);
-           float complex conjf(float complex z);
-           long double complex conjl(long double complex z);
-    Description
-2   The conj functions compute the complex conjugate of z, by reversing the sign of its
-    imaginary part.
-    Returns
-3   The conj functions return the complex conjugate value.
-    7.3.9.5 The cproj functions
-    Synopsis
-1          #include <complex.h>
-           double complex cproj(double complex z);
-           float complex cprojf(float complex z);
-           long double complex cprojl(long double complex z);
-    Description
-2   The cproj functions compute a projection of z onto the Riemann sphere: z projects to
-    z except that all complex infinities (even those with one infinite part and one NaN part)
-    project to positive infinity on the real axis. If z has an infinite part, then cproj(z) is
-    equivalent to
-           INFINITY + I * copysign(0.0, cimag(z))
-    Returns
-3   The cproj functions return the value of the projection onto the Riemann sphere.
-    7.3.9.6 The creal functions
-    Synopsis
-1          #include <complex.h>
-           double creal(double complex z);
-           float crealf(float complex z);
-           long double creall(long double complex z);
-    Description
-2   The creal functions compute the real part of z.195)
-
-
-[page 196] (Contents)
-
-    Returns
-3   The creal functions return the real part value.
-
-
-
-
-    195) For a variable z of complex type, z == creal(z) + cimag(z)*I.
-
-[page 197] (Contents)
-
-    7.4 Character handling <ctype.h>
-1   The header <ctype.h> declares several functions useful for classifying and mapping
-    characters.196) In all cases the argument is an int, the value of which shall be
-    representable as an unsigned char or shall equal the value of the macro EOF. If the
-    argument has any other value, the behavior is undefined.
-2   The behavior of these functions is affected by the current locale. Those functions that
-    have locale-specific aspects only when not in the "C" locale are noted below.
-3   The term printing character refers to a member of a locale-specific set of characters, each
-    of which occupies one printing position on a display device; the term control character
-    refers to a member of a locale-specific set of characters that are not printing
-    characters.197) All letters and digits are printing characters.
-    Forward references: EOF (7.21.1), localization (7.11).
-    7.4.1 Character classification functions
-1   The functions in this subclause return nonzero (true) if and only if the value of the
-    argument c conforms to that in the description of the function.
-    7.4.1.1 The isalnum function
-    Synopsis
-1            #include <ctype.h>
-             int isalnum(int c);
-    Description
-2   The isalnum function tests for any character for which isalpha or isdigit is true.
-    7.4.1.2 The isalpha function
-    Synopsis
-1            #include <ctype.h>
-             int isalpha(int c);
-    Description
-2   The isalpha function tests for any character for which isupper or islower is true,
-    or any character that is one of a locale-specific set of alphabetic characters for which
-
-
-
-    196) See ''future library directions'' (7.30.2).
-    197) In an implementation that uses the seven-bit US ASCII character set, the printing characters are those
-         whose values lie from 0x20 (space) through 0x7E (tilde); the control characters are those whose
-         values lie from 0 (NUL) through 0x1F (US), and the character 0x7F (DEL).
-
-[page 198] (Contents)
-
-    none of iscntrl, isdigit, ispunct, or isspace is true.198) In the "C" locale,
-    isalpha returns true only for the characters for which isupper or islower is true.
-    7.4.1.3 The isblank function
-    Synopsis
-1           #include <ctype.h>
-            int isblank(int c);
-    Description
-2   The isblank function tests for any character that is a standard blank character or is one
-    of a locale-specific set of characters for which isspace is true and that is used to
-    separate words within a line of text. The standard blank characters are the following:
-    space (' '), and horizontal tab ('\t'). In the "C" locale, isblank returns true only
-    for the standard blank characters.
-    7.4.1.4 The iscntrl function
-    Synopsis
-1           #include <ctype.h>
-            int iscntrl(int c);
-    Description
-2   The iscntrl function tests for any control character.
-    7.4.1.5 The isdigit function
-    Synopsis
-1           #include <ctype.h>
-            int isdigit(int c);
-    Description
-2   The isdigit function tests for any decimal-digit character (as defined in 5.2.1).
-    7.4.1.6 The isgraph function
-    Synopsis
-1           #include <ctype.h>
-            int isgraph(int c);
-
-
-
-
-    198) The functions islower and isupper test true or false separately for each of these additional
-         characters; all four combinations are possible.
-
-[page 199] (Contents)
-
-    Description
-2   The isgraph function tests for any printing character except space (' ').
-    7.4.1.7 The islower function
-    Synopsis
-1          #include <ctype.h>
-           int islower(int c);
-    Description
-2   The islower function tests for any character that is a lowercase letter or is one of a
-    locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
-    isspace is true. In the "C" locale, islower returns true only for the lowercase
-    letters (as defined in 5.2.1).
-    7.4.1.8 The isprint function
-    Synopsis
-1          #include <ctype.h>
-           int isprint(int c);
-    Description
-2   The isprint function tests for any printing character including space (' ').
-    7.4.1.9 The ispunct function
-    Synopsis
-1          #include <ctype.h>
-           int ispunct(int c);
-    Description
-2   The ispunct function tests for any printing character that is one of a locale-specific set
-    of punctuation characters for which neither isspace nor isalnum is true. In the "C"
-    locale, ispunct returns true for every printing character for which neither isspace
-    nor isalnum is true.
-    7.4.1.10 The isspace function
-    Synopsis
-1          #include <ctype.h>
-           int isspace(int c);
-    Description
-2   The isspace function tests for any character that is a standard white-space character or
-    is one of a locale-specific set of characters for which isalnum is false. The standard
-
-[page 200] (Contents)
-
-    white-space characters are the following: space (' '), form feed ('\f'), new-line
-    ('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v'). In the
-    "C" locale, isspace returns true only for the standard white-space characters.
-    7.4.1.11 The isupper function
-    Synopsis
-1           #include <ctype.h>
-            int isupper(int c);
-    Description
-2   The isupper function tests for any character that is an uppercase letter or is one of a
-    locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
-    isspace is true. In the "C" locale, isupper returns true only for the uppercase
-    letters (as defined in 5.2.1).
-    7.4.1.12 The isxdigit function
-    Synopsis
-1           #include <ctype.h>
-            int isxdigit(int c);
-    Description
-2   The isxdigit function tests for any hexadecimal-digit character (as defined in 6.4.4.1).
-    7.4.2 Character case mapping functions
-    7.4.2.1 The tolower function
-    Synopsis
-1           #include <ctype.h>
-            int tolower(int c);
-    Description
-2   The tolower function converts an uppercase letter to a corresponding lowercase letter.
-    Returns
-3   If the argument is a character for which isupper is true and there are one or more
-    corresponding characters, as specified by the current locale, for which islower is true,
-    the tolower function returns one of the corresponding characters (always the same one
-    for any given locale); otherwise, the argument is returned unchanged.
-
-
-
-
-[page 201] (Contents)
-
-    7.4.2.2 The toupper function
-    Synopsis
-1          #include <ctype.h>
-           int toupper(int c);
-    Description
-2   The toupper function converts a lowercase letter to a corresponding uppercase letter.
-    Returns
-3   If the argument is a character for which islower is true and there are one or more
-    corresponding characters, as specified by the current locale, for which isupper is true,
-    the toupper function returns one of the corresponding characters (always the same one
-    for any given locale); otherwise, the argument is returned unchanged.
-
-
-
-
-[page 202] (Contents)
-
-    7.5 Errors <errno.h>
-1   The header <errno.h> defines several macros, all relating to the reporting of error
-    conditions.
-2   The macros are
-             EDOM
-             EILSEQ
-             ERANGE
-    which expand to integer constant expressions with type int, distinct positive values, and
-    which are suitable for use in #if preprocessing directives; and
-             errno
-    which expands to a modifiable lvalue199) that has type int and thread local storage
-    duration, the value of which is set to a positive error number by several library functions.
-    If a macro definition is suppressed in order to access an actual object, or a program
-    defines an identifier with the name errno, the behavior is undefined.
-3   The value of errno in the initial thread is zero at program startup (the initial value of
-    errno in other threads is an indeterminate value), but is never set to zero by any library
-    function.200) The value of errno may be set to nonzero by a library function call
-    whether or not there is an error, provided the use of errno is not documented in the
-    description of the function in this International Standard.
-4   Additional macro definitions, beginning with E and a digit or E and an uppercase
-    letter,201) may also be specified by the implementation.
-
-
-
-
-    199) The macro errno need not be the identifier of an object. It might expand to a modifiable lvalue
-         resulting from a function call (for example, *errno()).
-    200) Thus, a program that uses errno for error checking should set it to zero before a library function call,
-         then inspect it before a subsequent library function call. Of course, a library function can save the
-         value of errno on entry and then set it to zero, as long as the original value is restored if errno's
-         value is still zero just before the return.
-    201) See ''future library directions'' (7.30.3).
-
-[page 203] (Contents)
-
-    7.6 Floating-point environment <fenv.h>
-1   The header <fenv.h> defines several macros, and declares types and functions that
-    provide access to the floating-point environment. The floating-point environment refers
-    collectively to any floating-point status flags and control modes supported by the
-    implementation.202) A floating-point status flag is a system variable whose value is set
-    (but never cleared) when a floating-point exception is raised, which occurs as a side effect
-    of exceptional floating-point arithmetic to provide auxiliary information.203) A floating-
-    point control mode is a system variable whose value may be set by the user to affect the
-    subsequent behavior of floating-point arithmetic.
-2   The floating-point environment has thread storage duration. The initial state for a
-    thread's floating-point environment is the current state of the floating-point environment
-    of the thread that creates it at the time of creation.
-3   Certain programming conventions support the intended model of use for the floating-
-    point environment:204)
-    -- a function call does not alter its caller's floating-point control modes, clear its caller's
-      floating-point status flags, nor depend on the state of its caller's floating-point status
-      flags unless the function is so documented;
-    -- a function call is assumed to require default floating-point control modes, unless its
-      documentation promises otherwise;
-    -- a function call is assumed to have the potential for raising floating-point exceptions,
-      unless its documentation promises otherwise.
-4   The type
-            fenv_t
-    represents the entire floating-point environment.
-5   The type
-            fexcept_t
-    represents the floating-point status flags collectively, including any status the
-    implementation associates with the flags.
-
-
-    202) This header is designed to support the floating-point exception status flags and directed-rounding
-         control modes required by IEC 60559, and other similar floating-point state information. Also it is
-         designed to facilitate code portability among all systems.
-    203) A floating-point status flag is not an object and can be set more than once within an expression.
-    204) With these conventions, a programmer can safely assume default floating-point control modes (or be
-         unaware of them). The responsibilities associated with accessing the floating-point environment fall
-         on the programmer or program that does so explicitly.
-
-[page 204] (Contents)
-
-6   Each of the macros
-             FE_DIVBYZERO
-             FE_INEXACT
-             FE_INVALID
-             FE_OVERFLOW
-             FE_UNDERFLOW
-    is defined if and only if the implementation supports the floating-point exception by
-    means of the functions in 7.6.2.205) Additional implementation-defined floating-point
-    exceptions, with macro definitions beginning with FE_ and an uppercase letter, may also
-    be specified by the implementation. The defined macros expand to integer constant
-    expressions with values such that bitwise ORs of all combinations of the macros result in
-    distinct values, and furthermore, bitwise ANDs of all combinations of the macros result in
-    zero.206)
-7   The macro
-             FE_ALL_EXCEPT
-    is simply the bitwise OR of all floating-point exception macros defined by the
-    implementation. If no such macros are defined, FE_ALL_EXCEPT shall be defined as 0.
-8   Each of the macros
-            FE_DOWNWARD
-            FE_TONEAREST
-            FE_TOWARDZERO
-            FE_UPWARD
-    is defined if and only if the implementation supports getting and setting the represented
-    rounding direction by means of the fegetround and fesetround functions.
-    Additional implementation-defined rounding directions, with macro definitions beginning
-    with FE_ and an uppercase letter, may also be specified by the implementation. The
-    defined macros expand to integer constant expressions whose values are distinct
-    nonnegative values.207)
-9   The macro
-
-
-
-    205) The implementation supports an exception if there are circumstances where a call to at least one of the
-         functions in 7.6.2, using the macro as the appropriate argument, will succeed. It is not necessary for
-         all the functions to succeed all the time.
-    206) The macros should be distinct powers of two.
-    207) Even though the rounding direction macros may expand to constants corresponding to the values of
-         FLT_ROUNDS, they are not required to do so.
-
-[page 205] (Contents)
-
-             FE_DFL_ENV
-     represents the default floating-point environment -- the one installed at program startup
-     -- and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to
-     <fenv.h> functions that manage the floating-point environment.
-10   Additional implementation-defined environments, with macro definitions beginning with
-     FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may
-     also be specified by the implementation.
-     7.6.1 The FENV_ACCESS pragma
-     Synopsis
-1            #include <fenv.h>
-             #pragma STDC FENV_ACCESS on-off-switch
-     Description
-2    The FENV_ACCESS pragma provides a means to inform the implementation when a
-     program might access the floating-point environment to test floating-point status flags or
-     run under non-default floating-point control modes.208) The pragma shall occur either
-     outside external declarations or preceding all explicit declarations and statements inside a
-     compound statement. When outside external declarations, the pragma takes effect from
-     its occurrence until another FENV_ACCESS pragma is encountered, or until the end of
-     the translation unit. When inside a compound statement, the pragma takes effect from its
-     occurrence until another FENV_ACCESS pragma is encountered (including within a
-     nested compound statement), or until the end of the compound statement; at the end of a
-     compound statement the state for the pragma is restored to its condition just before the
-     compound statement. If this pragma is used in any other context, the behavior is
-     undefined. If part of a program tests floating-point status flags, sets floating-point control
-     modes, or runs under non-default mode settings, but was translated with the state for the
-     FENV_ACCESS pragma ''off'', the behavior is undefined. The default state (''on'' or
-     ''off'') for the pragma is implementation-defined. (When execution passes from a part of
-     the program translated with FENV_ACCESS ''off'' to a part translated with
-     FENV_ACCESS ''on'', the state of the floating-point status flags is unspecified and the
-     floating-point control modes have their default settings.)
-
-
-
-
-     208) The purpose of the FENV_ACCESS pragma is to allow certain optimizations that could subvert flag
-          tests and mode changes (e.g., global common subexpression elimination, code motion, and constant
-          folding). In general, if the state of FENV_ACCESS is ''off'', the translator can assume that default
-          modes are in effect and the flags are not tested.
-
-[page 206] (Contents)
-
-3   EXAMPLE
-            #include <fenv.h>
-            void f(double x)
-            {
-                  #pragma STDC FENV_ACCESS ON
-                  void g(double);
-                  void h(double);
-                  /* ... */
-                  g(x + 1);
-                  h(x + 1);
-                  /* ... */
-            }
-4   If the function g might depend on status flags set as a side effect of the first x + 1, or if the second
-    x + 1 might depend on control modes set as a side effect of the call to function g, then the program shall
-    contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.209)
-
-    7.6.2 Floating-point exceptions
-1   The following functions provide access to the floating-point status flags.210) The int
-    input argument for the functions represents a subset of floating-point exceptions, and can
-    be zero or the bitwise OR of one or more floating-point exception macros, for example
-    FE_OVERFLOW | FE_INEXACT. For other argument values the behavior of these
-    functions is undefined.
-    7.6.2.1 The feclearexcept function
-    Synopsis
-1           #include <fenv.h>
-            int feclearexcept(int excepts);
-    Description
-2   The feclearexcept function attempts to clear the supported floating-point exceptions
-    represented by its argument.
-    Returns
-3   The feclearexcept function returns zero if the excepts argument is zero or if all
-    the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value.
-
-
-    209) The side effects impose a temporal ordering that requires two evaluations of x + 1. On the other
-         hand, without the #pragma STDC FENV_ACCESS ON pragma, and assuming the default state is
-         ''off'', just one evaluation of x + 1 would suffice.
-    210) The functions fetestexcept, feraiseexcept, and feclearexcept support the basic
-         abstraction of flags that are either set or clear. An implementation may endow floating-point status
-         flags with more information -- for example, the address of the code which first raised the floating-
-         point exception; the functions fegetexceptflag and fesetexceptflag deal with the full
-         content of flags.
-
-[page 207] (Contents)
-
-    7.6.2.2 The fegetexceptflag function
-    Synopsis
-1            #include <fenv.h>
-             int fegetexceptflag(fexcept_t *flagp,
-                  int excepts);
-    Description
-2   The fegetexceptflag function attempts to store an implementation-defined
-    representation of the states of the floating-point status flags indicated by the argument
-    excepts in the object pointed to by the argument flagp.
-    Returns
-3   The fegetexceptflag function returns zero if the representation was successfully
-    stored. Otherwise, it returns a nonzero value.
-    7.6.2.3 The feraiseexcept function
-    Synopsis
-1            #include <fenv.h>
-             int feraiseexcept(int excepts);
-    Description
-2   The feraiseexcept function attempts to raise the supported floating-point exceptions
-    represented by its argument.211) The order in which these floating-point exceptions are
-    raised is unspecified, except as stated in F.8.6. Whether the feraiseexcept function
-    additionally raises the ''inexact'' floating-point exception whenever it raises the
-    ''overflow'' or ''underflow'' floating-point exception is implementation-defined.
-    Returns
-3   The feraiseexcept function returns zero if the excepts argument is zero or if all
-    the specified exceptions were successfully raised. Otherwise, it returns a nonzero value.
-
-
-
-
-    211) The effect is intended to be similar to that of floating-point exceptions raised by arithmetic operations.
-         Hence, enabled traps for floating-point exceptions raised by this function are taken. The specification
-         in F.8.6 is in the same spirit.
-
-[page 208] (Contents)
-
-    7.6.2.4 The fesetexceptflag function
-    Synopsis
-1           #include <fenv.h>
-            int fesetexceptflag(const fexcept_t *flagp,
-                 int excepts);
-    Description
-2   The fesetexceptflag function attempts to set the floating-point status flags
-    indicated by the argument excepts to the states stored in the object pointed to by
-    flagp. The value of *flagp shall have been set by a previous call to
-    fegetexceptflag whose second argument represented at least those floating-point
-    exceptions represented by the argument excepts. This function does not raise floating-
-    point exceptions, but only sets the state of the flags.
-    Returns
-3   The fesetexceptflag function returns zero if the excepts argument is zero or if
-    all the specified flags were successfully set to the appropriate state. Otherwise, it returns
-    a nonzero value.
-    7.6.2.5 The fetestexcept function
-    Synopsis
-1           #include <fenv.h>
-            int fetestexcept(int excepts);
-    Description
-2   The fetestexcept function determines which of a specified subset of the floating-
-    point exception flags are currently set. The excepts argument specifies the floating-
-    point status flags to be queried.212)
-    Returns
-3   The fetestexcept function returns the value of the bitwise OR of the floating-point
-    exception macros corresponding to the currently set floating-point exceptions included in
-    excepts.
-4   EXAMPLE       Call f if ''invalid'' is set, then g if ''overflow'' is set:
-
-
-
-
-    212) This mechanism allows testing several floating-point exceptions with just one function call.
-
-[page 209] (Contents)
-
-           #include <fenv.h>
-           /* ... */
-           {
-                   #pragma STDC FENV_ACCESS ON
-                   int set_excepts;
-                   feclearexcept(FE_INVALID | FE_OVERFLOW);
-                   // maybe raise exceptions
-                   set_excepts = fetestexcept(FE_INVALID | FE_OVERFLOW);
-                   if (set_excepts & FE_INVALID) f();
-                   if (set_excepts & FE_OVERFLOW) g();
-                   /* ... */
-           }
-
-    7.6.3 Rounding
-1   The fegetround and fesetround functions provide control of rounding direction
-    modes.
-    7.6.3.1 The fegetround function
-    Synopsis
-1          #include <fenv.h>
-           int fegetround(void);
-    Description
-2   The fegetround function gets the current rounding direction.
-    Returns
-3   The fegetround function returns the value of the rounding direction macro
-    representing the current rounding direction or a negative value if there is no such
-    rounding direction macro or the current rounding direction is not determinable.
-    7.6.3.2 The fesetround function
-    Synopsis
-1          #include <fenv.h>
-           int fesetround(int round);
-    Description
-2   The fesetround function establishes the rounding direction represented by its
-    argument round. If the argument is not equal to the value of a rounding direction macro,
-    the rounding direction is not changed.
-    Returns
-3   The fesetround function returns zero if and only if the requested rounding direction
-    was established.
-
-
-[page 210] (Contents)
-
-4   EXAMPLE Save, set, and restore the rounding direction. Report an error and abort if setting the
-    rounding direction fails.
-            #include <fenv.h>
-            #include <assert.h>
-            void f(int round_dir)
-            {
-                  #pragma STDC FENV_ACCESS ON
-                  int save_round;
-                  int setround_ok;
-                  save_round = fegetround();
-                  setround_ok = fesetround(round_dir);
-                  assert(setround_ok == 0);
-                  /* ... */
-                  fesetround(save_round);
-                  /* ... */
-            }
-
-    7.6.4 Environment
-1   The functions in this section manage the floating-point environment -- status flags and
-    control modes -- as one entity.
-    7.6.4.1 The fegetenv function
-    Synopsis
-1           #include <fenv.h>
-            int fegetenv(fenv_t *envp);
-    Description
-2   The fegetenv function attempts to store the current floating-point environment in the
-    object pointed to by envp.
-    Returns
-3   The fegetenv function returns zero if the environment was successfully stored.
-    Otherwise, it returns a nonzero value.
-    7.6.4.2 The feholdexcept function
-    Synopsis
-1           #include <fenv.h>
-            int feholdexcept(fenv_t *envp);
-    Description
-2   The feholdexcept function saves the current floating-point environment in the object
-    pointed to by envp, clears the floating-point status flags, and then installs a non-stop
-    (continue on floating-point exceptions) mode, if available, for all floating-point
-    exceptions.213)
-
-[page 211] (Contents)
-
-    Returns
-3   The feholdexcept function returns zero if and only if non-stop floating-point
-    exception handling was successfully installed.
-    7.6.4.3 The fesetenv function
-    Synopsis
-1           #include <fenv.h>
-            int fesetenv(const fenv_t *envp);
-    Description
-2   The fesetenv function attempts to establish the floating-point environment represented
-    by the object pointed to by envp. The argument envp shall point to an object set by a
-    call to fegetenv or feholdexcept, or equal a floating-point environment macro.
-    Note that fesetenv merely installs the state of the floating-point status flags
-    represented through its argument, and does not raise these floating-point exceptions.
-    Returns
-3   The fesetenv function returns zero if the environment was successfully established.
-    Otherwise, it returns a nonzero value.
-    7.6.4.4 The feupdateenv function
-    Synopsis
-1           #include <fenv.h>
-            int feupdateenv(const fenv_t *envp);
-    Description
-2   The feupdateenv function attempts to save the currently raised floating-point
-    exceptions in its automatic storage, install the floating-point environment represented by
-    the object pointed to by envp, and then raise the saved floating-point exceptions. The
-    argument envp shall point to an object set by a call to feholdexcept or fegetenv,
-    or equal a floating-point environment macro.
-    Returns
-3   The feupdateenv function returns zero if all the actions were successfully carried out.
-    Otherwise, it returns a nonzero value.
-
-
-
-
-    213) IEC 60559 systems have a default non-stop mode, and typically at least one other mode for trap
-         handling or aborting; if the system provides only the non-stop mode then installing it is trivial. For
-         such systems, the feholdexcept function can be used in conjunction with the feupdateenv
-         function to write routines that hide spurious floating-point exceptions from their callers.
-
-[page 212] (Contents)
-
-4   EXAMPLE     Hide spurious underflow floating-point exceptions:
-            #include <fenv.h>
-            double f(double x)
-            {
-                  #pragma STDC FENV_ACCESS ON
-                  double result;
-                  fenv_t save_env;
-                  if (feholdexcept(&save_env))
-                        return /* indication of an environmental problem */;
-                  // compute result
-                  if (/* test spurious underflow */)
-                        if (feclearexcept(FE_UNDERFLOW))
-                                 return /* indication of an environmental problem */;
-                  if (feupdateenv(&save_env))
-                        return /* indication of an environmental problem */;
-                  return result;
-            }
-
-
-
-
-[page 213] (Contents)
-
-    7.7 Characteristics of floating types <float.h>
-1   The header <float.h> defines several macros that expand to various limits and
-    parameters of the standard floating-point types.
-2   The macros, their meanings, and the constraints (or restrictions) on their values are listed
-    in 5.2.4.2.2.
-
-
-
-
-[page 214] (Contents)
-
-    7.8 Format conversion of integer types <inttypes.h>
-1   The header <inttypes.h> includes the header <stdint.h> and extends it with
-    additional facilities provided by hosted implementations.
-2   It declares functions for manipulating greatest-width integers and converting numeric
-    character strings to greatest-width integers, and it declares the type
-             imaxdiv_t
-    which is a structure type that is the type of the value returned by the imaxdiv function.
-    For each type declared in <stdint.h>, it defines corresponding macros for conversion
-    specifiers for use with the formatted input/output functions.214)
-    Forward references: integer types <stdint.h> (7.20), formatted input/output
-    functions (7.21.6), formatted wide character input/output functions (7.28.2).
-    7.8.1 Macros for format specifiers
-1   Each of the following object-like macros expands to a character string literal containing a
-    conversion specifier, possibly modified by a length modifier, suitable for use within the
-    format argument of a formatted input/output function when converting the corresponding
-    integer type. These macro names have the general form of PRI (character string literals
-    for the fprintf and fwprintf family) or SCN (character string literals for the
-    fscanf and fwscanf family),215) followed by the conversion specifier, followed by a
-    name corresponding to a similar type name in 7.20.1. In these names, N represents the
-    width of the type as described in 7.20.1. For example, PRIdFAST32 can be used in a
-    format string to print the value of an integer of type int_fast32_t.
-2   The fprintf macros for signed integers are:
-           PRIdN             PRIdLEASTN                PRIdFASTN          PRIdMAX             PRIdPTR
-           PRIiN             PRIiLEASTN                PRIiFASTN          PRIiMAX             PRIiPTR
-3   The fprintf macros for unsigned integers are:
-           PRIoN             PRIoLEASTN                PRIoFASTN          PRIoMAX             PRIoPTR
-           PRIuN             PRIuLEASTN                PRIuFASTN          PRIuMAX             PRIuPTR
-           PRIxN             PRIxLEASTN                PRIxFASTN          PRIxMAX             PRIxPTR
-           PRIXN             PRIXLEASTN                PRIXFASTN          PRIXMAX             PRIXPTR
-4   The fscanf macros for signed integers are:
-
-
-
-    214) See ''future library directions'' (7.30.4).
-    215) Separate macros are given for use with fprintf and fscanf functions because, in the general case,
-         different format specifiers may be required for fprintf and fscanf, even when the type is the
-         same.
-
-[page 215] (Contents)
-
-           SCNdN           SCNdLEASTN               SCNdFASTN              SCNdMAX             SCNdPTR
-           SCNiN           SCNiLEASTN               SCNiFASTN              SCNiMAX             SCNiPTR
-5   The fscanf macros for unsigned integers are:
-           SCNoN           SCNoLEASTN               SCNoFASTN              SCNoMAX             SCNoPTR
-           SCNuN           SCNuLEASTN               SCNuFASTN              SCNuMAX             SCNuPTR
-           SCNxN           SCNxLEASTN               SCNxFASTN              SCNxMAX             SCNxPTR
-6   For each type that the implementation provides in <stdint.h>, the corresponding
-    fprintf macros shall be defined and the corresponding fscanf macros shall be
-    defined unless the implementation does not have a suitable fscanf length modifier for
-    the type.
-7   EXAMPLE
-            #include <inttypes.h>
-            #include <wchar.h>
-            int main(void)
-            {
-                  uintmax_t i = UINTMAX_MAX;    // this type always exists
-                  wprintf(L"The largest integer value is %020"
-                        PRIxMAX "\n", i);
-                  return 0;
-            }
-
-    7.8.2 Functions for greatest-width integer types
-    7.8.2.1 The imaxabs function
-    Synopsis
-1           #include <inttypes.h>
-            intmax_t imaxabs(intmax_t j);
-    Description
-2   The imaxabs function computes the absolute value of an integer j. If the result cannot
-    be represented, the behavior is undefined.216)
-    Returns
-3   The imaxabs function returns the absolute value.
-
-
-
-
-    216) The absolute value of the most negative number cannot be represented in two's complement.
-
-[page 216] (Contents)
-
-    7.8.2.2 The imaxdiv function
-    Synopsis
-1           #include <inttypes.h>
-            imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
-    Description
-2   The imaxdiv function computes numer / denom and numer % denom in a single
-    operation.
-    Returns
-3   The imaxdiv function returns a structure of type imaxdiv_t comprising both the
-    quotient and the remainder. The structure shall contain (in either order) the members
-    quot (the quotient) and rem (the remainder), each of which has type intmax_t. If
-    either part of the result cannot be represented, the behavior is undefined.
-    7.8.2.3 The strtoimax and strtoumax functions
-    Synopsis
-1           #include <inttypes.h>
-            intmax_t strtoimax(const char * restrict nptr,
-                 char ** restrict endptr, int base);
-            uintmax_t strtoumax(const char * restrict nptr,
-                 char ** restrict endptr, int base);
-    Description
-2   The strtoimax and strtoumax functions are equivalent to the strtol, strtoll,
-    strtoul, and strtoull functions, except that the initial portion of the string is
-    converted to intmax_t and uintmax_t representation, respectively.
-    Returns
-3   The strtoimax and strtoumax functions return the converted value, if any. If no
-    conversion could be performed, zero is returned. If the correct value is outside the range
-    of representable values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned
-    (according to the return type and sign of the value, if any), and the value of the macro
-    ERANGE is stored in errno.
-    Forward references: the strtol, strtoll, strtoul, and strtoull functions
-    (7.22.1.4).
-
-
-
-
-[page 217] (Contents)
-
-    7.8.2.4 The wcstoimax and wcstoumax functions
-    Synopsis
-1          #include <stddef.h>           // for wchar_t
-           #include <inttypes.h>
-           intmax_t wcstoimax(const wchar_t * restrict nptr,
-                wchar_t ** restrict endptr, int base);
-           uintmax_t wcstoumax(const wchar_t * restrict nptr,
-                wchar_t ** restrict endptr, int base);
-    Description
-2   The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll,
-    wcstoul, and wcstoull functions except that the initial portion of the wide string is
-    converted to intmax_t and uintmax_t representation, respectively.
-    Returns
-3   The wcstoimax function returns the converted value, if any. If no conversion could be
-    performed, zero is returned. If the correct value is outside the range of representable
-    values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned (according to the
-    return type and sign of the value, if any), and the value of the macro ERANGE is stored in
-    errno.
-    Forward references: the wcstol, wcstoll, wcstoul, and wcstoull functions
-    (7.28.4.1.2).
-
-
-
-
-[page 218] (Contents)
-
-    7.9 Alternative spellings <iso646.h>
-1   The header <iso646.h> defines the following eleven macros (on the left) that expand
-    to the corresponding tokens (on the right):
-            and        &&
-            and_eq     &=
-            bitand     &
-            bitor      |
-            compl      ~
-            not        !
-            not_eq     !=
-            or         ||
-            or_eq      |=
-            xor        ^
-            xor_eq     ^=
-
-
-
-
-[page 219] (Contents)
-
-    7.10 Sizes of integer types <limits.h>
-1   The header <limits.h> defines several macros that expand to various limits and
-    parameters of the standard integer types.
-2   The macros, their meanings, and the constraints (or restrictions) on their values are listed
-    in 5.2.4.2.1.
-
-
-
-
-[page 220] (Contents)
-
-    7.11 Localization <locale.h>
-1   The header <locale.h> declares two functions, one type, and defines several macros.
-2   The type is
-            struct lconv
-    which contains members related to the formatting of numeric values. The structure shall
-    contain at least the following members, in any order. The semantics of the members and
-    their normal ranges are explained in 7.11.2.1. In the "C" locale, the members shall have
-    the values specified in the comments.
-            char   *decimal_point;                //   "."
-            char   *thousands_sep;                //   ""
-            char   *grouping;                     //   ""
-            char   *mon_decimal_point;            //   ""
-            char   *mon_thousands_sep;            //   ""
-            char   *mon_grouping;                 //   ""
-            char   *positive_sign;                //   ""
-            char   *negative_sign;                //   ""
-            char   *currency_symbol;              //   ""
-            char   frac_digits;                   //   CHAR_MAX
-            char   p_cs_precedes;                 //   CHAR_MAX
-            char   n_cs_precedes;                 //   CHAR_MAX
-            char   p_sep_by_space;                //   CHAR_MAX
-            char   n_sep_by_space;                //   CHAR_MAX
-            char   p_sign_posn;                   //   CHAR_MAX
-            char   n_sign_posn;                   //   CHAR_MAX
-            char   *int_curr_symbol;              //   ""
-            char   int_frac_digits;               //   CHAR_MAX
-            char   int_p_cs_precedes;             //   CHAR_MAX
-            char   int_n_cs_precedes;             //   CHAR_MAX
-            char   int_p_sep_by_space;            //   CHAR_MAX
-            char   int_n_sep_by_space;            //   CHAR_MAX
-            char   int_p_sign_posn;               //   CHAR_MAX
-            char   int_n_sign_posn;               //   CHAR_MAX
-
-
-
-
-[page 221] (Contents)
-
-3   The macros defined are NULL (described in 7.19); and
-             LC_ALL
-             LC_COLLATE
-             LC_CTYPE
-             LC_MONETARY
-             LC_NUMERIC
-             LC_TIME
-    which expand to integer constant expressions with distinct values, suitable for use as the
-    first argument to the setlocale function.217) Additional macro definitions, beginning
-    with the characters LC_ and an uppercase letter,218) may also be specified by the
-    implementation.
-    7.11.1 Locale control
-    7.11.1.1 The setlocale function
-    Synopsis
-1            #include <locale.h>
-             char *setlocale(int category, const char *locale);
-    Description
-2   The setlocale function selects the appropriate portion of the program's locale as
-    specified by the category and locale arguments. The setlocale function may be
-    used to change or query the program's entire current locale or portions thereof. The value
-    LC_ALL for category names the program's entire locale; the other values for
-    category name only a portion of the program's locale. LC_COLLATE affects the
-    behavior of the strcoll and strxfrm functions. LC_CTYPE affects the behavior of
-    the character handling functions219) and the multibyte and wide character functions.
-    LC_MONETARY affects the monetary formatting information returned by the
-    localeconv function. LC_NUMERIC affects the decimal-point character for the
-    formatted input/output functions and the string conversion functions, as well as the
-    nonmonetary formatting information returned by the localeconv function. LC_TIME
-    affects the behavior of the strftime and wcsftime functions.
-3   A value of "C" for locale specifies the minimal environment for C translation; a value
-    of "" for locale specifies the locale-specific native environment. Other
-    implementation-defined strings may be passed as the second argument to setlocale.
-
-    217) ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C.
-    218) See ''future library directions'' (7.30.5).
-    219) The only functions in 7.4 whose behavior is not affected by the current locale are isdigit and
-         isxdigit.
-
-[page 222] (Contents)
-
-4   At program startup, the equivalent of
-            setlocale(LC_ALL, "C");
-    is executed.
-5   A call to the setlocale function may introduce a data race with other calls to the
-    setlocale function or with calls to functions that are affected by the current locale.
-    The implementation shall behave as if no library function calls the setlocale function.
-    Returns
-6   If a pointer to a string is given for locale and the selection can be honored, the
-    setlocale function returns a pointer to the string associated with the specified
-    category for the new locale. If the selection cannot be honored, the setlocale
-    function returns a null pointer and the program's locale is not changed.
-7   A null pointer for locale causes the setlocale function to return a pointer to the
-    string associated with the category for the program's current locale; the program's
-    locale is not changed.220)
-8   The pointer to string returned by the setlocale function is such that a subsequent call
-    with that string value and its associated category will restore that part of the program's
-    locale. The string pointed to shall not be modified by the program, but may be
-    overwritten by a subsequent call to the setlocale function.
-    Forward references: formatted input/output functions (7.21.6), multibyte/wide
-    character conversion functions (7.22.7), multibyte/wide string conversion functions
-    (7.22.8), numeric conversion functions (7.22.1), the strcoll function (7.23.4.3), the
-    strftime function (7.26.3.5), the strxfrm function (7.23.4.5).
-    7.11.2 Numeric formatting convention inquiry
-    7.11.2.1 The localeconv function
-    Synopsis
-1           #include <locale.h>
-            struct lconv *localeconv(void);
-    Description
-2   The localeconv function sets the components of an object with type struct lconv
-    with values appropriate for the formatting of numeric quantities (monetary and otherwise)
-    according to the rules of the current locale.
-
-
-
-    220) The implementation shall arrange to encode in a string the various categories due to a heterogeneous
-         locale when category has the value LC_ALL.
-
-[page 223] (Contents)
-
-3   The members of the structure with type char * are pointers to strings, any of which
-    (except decimal_point) can point to "", to indicate that the value is not available in
-    the current locale or is of zero length. Apart from grouping and mon_grouping, the
-    strings shall start and end in the initial shift state. The members with type char are
-    nonnegative numbers, any of which can be CHAR_MAX to indicate that the value is not
-    available in the current locale. The members include the following:
-    char *decimal_point
-              The decimal-point character used to format nonmonetary quantities.
-    char *thousands_sep
-              The character used to separate groups of digits before the decimal-point
-              character in formatted nonmonetary quantities.
-    char *grouping
-              A string whose elements indicate the size of each group of digits in
-              formatted nonmonetary quantities.
-    char *mon_decimal_point
-              The decimal-point used to format monetary quantities.
-    char *mon_thousands_sep
-              The separator for groups of digits before the decimal-point in formatted
-              monetary quantities.
-    char *mon_grouping
-              A string whose elements indicate the size of each group of digits in
-              formatted monetary quantities.
-    char *positive_sign
-              The string used to indicate a nonnegative-valued formatted monetary
-              quantity.
-    char *negative_sign
-              The string used to indicate a negative-valued formatted monetary quantity.
-    char *currency_symbol
-              The local currency symbol applicable to the current locale.
-    char frac_digits
-              The number of fractional digits (those after the decimal-point) to be
-              displayed in a locally formatted monetary quantity.
-    char p_cs_precedes
-              Set to 1 or 0 if the currency_symbol respectively precedes or
-              succeeds the value for a nonnegative locally formatted monetary quantity.
-
-
-
-[page 224] (Contents)
-
-char n_cs_precedes
-          Set to 1 or 0 if the currency_symbol respectively precedes or
-          succeeds the value for a negative locally formatted monetary quantity.
-char p_sep_by_space
-          Set to a value indicating the separation of the currency_symbol, the
-          sign string, and the value for a nonnegative locally formatted monetary
-          quantity.
-char n_sep_by_space
-          Set to a value indicating the separation of the currency_symbol, the
-          sign string, and the value for a negative locally formatted monetary
-          quantity.
-char p_sign_posn
-          Set to a value indicating the positioning of the positive_sign for a
-          nonnegative locally formatted monetary quantity.
-char n_sign_posn
-          Set to a value indicating the positioning of the negative_sign for a
-          negative locally formatted monetary quantity.
-char *int_curr_symbol
-          The international currency symbol applicable to the current locale. The
-          first three characters contain the alphabetic international currency symbol
-          in accordance with those specified in ISO 4217. The fourth character
-          (immediately preceding the null character) is the character used to separate
-          the international currency symbol from the monetary quantity.
-char int_frac_digits
-          The number of fractional digits (those after the decimal-point) to be
-          displayed in an internationally formatted monetary quantity.
-char int_p_cs_precedes
-          Set to 1 or 0 if the int_curr_symbol respectively precedes or
-          succeeds the value for a nonnegative internationally formatted monetary
-          quantity.
-char int_n_cs_precedes
-          Set to 1 or 0 if the int_curr_symbol respectively precedes or
-          succeeds the value for a negative internationally formatted monetary
-          quantity.
-char int_p_sep_by_space
-          Set to a value indicating the separation of the int_curr_symbol, the
-          sign string, and the value for a nonnegative internationally formatted
-          monetary quantity.
-[page 225] (Contents)
-
-    char int_n_sep_by_space
-              Set to a value indicating the separation of the int_curr_symbol, the
-              sign string, and the value for a negative internationally formatted monetary
-              quantity.
-    char int_p_sign_posn
-              Set to a value indicating the positioning of the positive_sign for a
-              nonnegative internationally formatted monetary quantity.
-    char int_n_sign_posn
-              Set to a value indicating the positioning of the negative_sign for a
-              negative internationally formatted monetary quantity.
-4   The elements of grouping and mon_grouping are interpreted according to the
-    following:
-    CHAR_MAX        No further grouping is to be performed.
-    0               The previous element is to be repeatedly used for the remainder of the
-                    digits.
-    other           The integer value is the number of digits that compose the current group.
-                    The next element is examined to determine the size of the next group of
-                    digits before the current group.
-5   The values of p_sep_by_space, n_sep_by_space, int_p_sep_by_space,
-    and int_n_sep_by_space are interpreted according to the following:
-    0     No space separates the currency symbol and value.
-    1     If the currency symbol and sign string are adjacent, a space separates them from the
-          value; otherwise, a space separates the currency symbol from the value.
-    2   If the currency symbol and sign string are adjacent, a space separates them;
-        otherwise, a space separates the sign string from the value.
-    For int_p_sep_by_space and int_n_sep_by_space, the fourth character of
-    int_curr_symbol is used instead of a space.
-6   The values of p_sign_posn, n_sign_posn, int_p_sign_posn,                              and
-    int_n_sign_posn are interpreted according to the following:
-    0     Parentheses surround the quantity and currency symbol.
-    1     The sign string precedes the quantity and currency symbol.
-    2     The sign string succeeds the quantity and currency symbol.
-    3     The sign string immediately precedes the currency symbol.
-    4     The sign string immediately succeeds the currency symbol.
-
-
-[page 226] (Contents)
-
-7    The implementation shall behave as if no library function calls the localeconv
-     function.
-     Returns
-8    The localeconv function returns a pointer to the filled-in object. The structure
-     pointed to by the return value shall not be modified by the program, but may be
-     overwritten by a subsequent call to the localeconv function. In addition, calls to the
-     setlocale function with categories LC_ALL, LC_MONETARY, or LC_NUMERIC may
-     overwrite the contents of the structure.
-9    EXAMPLE 1 The following table illustrates rules which may well be used by four countries to format
-     monetary quantities.
-                                   Local format                                     International format
-
-     Country            Positive                  Negative                    Positive               Negative
-
-     Country1     1.234,56 mk             -1.234,56 mk                  FIM   1.234,56         FIM -1.234,56
-     Country2     L.1.234                 -L.1.234                      ITL   1.234            -ITL 1.234
-     Country3     fl. 1.234,56              fl. -1.234,56                   NLG   1.234,56         NLG -1.234,56
-     Country4     SFrs.1,234.56           SFrs.1,234.56C                CHF   1,234.56         CHF 1,234.56C
-10   For these four countries, the respective values for the monetary members of the structure returned by
-     localeconv could be:
-                                       Country1              Country2              Country3            Country4
-
-     mon_decimal_point                 ","                   ""                   ","                 "."
-     mon_thousands_sep                 "."                   "."                  "."                 ","
-     mon_grouping                      "\3"                  "\3"                 "\3"                "\3"
-     positive_sign                     ""                    ""                   ""                  ""
-     negative_sign                     "-"                   "-"                  "-"                 "C"
-     currency_symbol                   "mk"                  "L."                 "\u0192"            "SFrs."
-     frac_digits                       2                     0                    2                   2
-     p_cs_precedes                     0                     1                    1                   1
-     n_cs_precedes                     0                     1                    1                   1
-     p_sep_by_space                    1                     0                    1                   0
-     n_sep_by_space                    1                     0                    2                   0
-     p_sign_posn                       1                     1                    1                   1
-     n_sign_posn                       1                     1                    4                   2
-     int_curr_symbol                   "FIM "                "ITL "               "NLG "              "CHF "
-     int_frac_digits                   2                     0                    2                   2
-     int_p_cs_precedes                 1                     1                    1                   1
-     int_n_cs_precedes                 1                     1                    1                   1
-     int_p_sep_by_space                1                     1                    1                   1
-     int_n_sep_by_space                2                     1                    2                   1
-     int_p_sign_posn                   1                     1                    1                   1
-     int_n_sign_posn                   4                     1                    4                   2
-
-
-
-
-[page 227] (Contents)
-
-11   EXAMPLE 2 The following table illustrates how the cs_precedes, sep_by_space, and sign_posn members
-     affect the formatted value.
-                                                                   p_sep_by_space
-
-     p_cs_precedes           p_sign_posn                0                   1                  2
-
-                     0                    0         (1.25$)            (1.25 $)            (1.25$)
-                                          1         +1.25$             +1.25 $             + 1.25$
-                                          2         1.25$+             1.25 $+             1.25$ +
-                                          3         1.25+$             1.25 +$             1.25+ $
-                                          4         1.25$+             1.25 $+             1.25$ +
-
-                     1                    0         ($1.25)            ($ 1.25)            ($1.25)
-                                          1         +$1.25             +$ 1.25             + $1.25
-                                          2         $1.25+             $ 1.25+             $1.25 +
-                                          3         +$1.25             +$ 1.25             + $1.25
-                                          4         $+1.25             $+ 1.25             $ +1.25
-
-
-
-
-[page 228] (Contents)
-
-    7.12 Mathematics <math.h>
-1   The header <math.h> declares two types and many mathematical functions and defines
-    several macros. Most synopses specify a family of functions consisting of a principal
-    function with one or more double parameters, a double return value, or both; and
-    other functions with the same name but with f and l suffixes, which are corresponding
-    functions with float and long double parameters, return values, or both.221)
-    Integer arithmetic functions and conversion functions are discussed later.
-2   The types
-            float_t
-            double_t
-    are floating types at least as wide as float and double, respectively, and such that
-    double_t is at least as wide as float_t. If FLT_EVAL_METHOD equals 0,
-    float_t and double_t are float and double, respectively; if
-    FLT_EVAL_METHOD equals 1, they are both double; if FLT_EVAL_METHOD equals
-    2, they are both long double; and for other values of FLT_EVAL_METHOD, they are
-    otherwise implementation-defined.222)
-3   The macro
-            HUGE_VAL
-    expands to a positive double constant expression, not necessarily representable as a
-    float. The macros
-            HUGE_VALF
-            HUGE_VALL
-    are respectively float and long double analogs of HUGE_VAL.223)
-4   The macro
-            INFINITY
-    expands to a constant expression of type float representing positive or unsigned
-    infinity, if available; else to a positive constant of type float that overflows at
-
-
-
-    221) Particularly on systems with wide expression evaluation, a <math.h> function might pass arguments
-         and return values in wider format than the synopsis prototype indicates.
-    222) The types float_t and double_t are intended to be the implementation's most efficient types at
-         least as wide as float and double, respectively. For FLT_EVAL_METHOD equal 0, 1, or 2, the
-         type float_t is the narrowest type used by the implementation to evaluate floating expressions.
-    223) HUGE_VAL, HUGE_VALF, and HUGE_VALL can be positive infinities in an implementation that
-         supports infinities.
-
-[page 229] (Contents)
-
-    translation time.224)
-5   The macro
-             NAN
-    is defined if and only if the implementation supports quiet NaNs for the float type. It
-    expands to a constant expression of type float representing a quiet NaN.
-6   The number classification macros
-             FP_INFINITE
-             FP_NAN
-             FP_NORMAL
-             FP_SUBNORMAL
-             FP_ZERO
-    represent the mutually exclusive kinds of floating-point values. They expand to integer
-    constant expressions with distinct values. Additional implementation-defined floating-
-    point classifications, with macro definitions beginning with FP_ and an uppercase letter,
-    may also be specified by the implementation.
-7   The macro
-             FP_FAST_FMA
-    is optionally defined. If defined, it indicates that the fma function generally executes
-    about as fast as, or faster than, a multiply and an add of double operands.225) The
-    macros
-             FP_FAST_FMAF
-             FP_FAST_FMAL
-    are, respectively, float and long double analogs of FP_FAST_FMA. If defined,
-    these macros expand to the integer constant 1.
-8   The macros
-             FP_ILOGB0
-             FP_ILOGBNAN
-    expand to integer constant expressions whose values are returned by ilogb(x) if x is
-    zero or NaN, respectively. The value of FP_ILOGB0 shall be either INT_MIN or
-    -INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN.
-
-
-    224) In this case, using INFINITY will violate the constraint in 6.4.4 and thus require a diagnostic.
-    225) Typically, the FP_FAST_FMA macro is defined if and only if the fma function is implemented
-         directly with a hardware multiply-add instruction. Software implementations are expected to be
-         substantially slower.
-
-[page 230] (Contents)
-
-9   The macros
-              MATH_ERRNO
-              MATH_ERREXCEPT
-    expand to the integer constants 1 and 2, respectively; the macro
-            math_errhandling
-    expands to an expression that has type int and the value MATH_ERRNO,
-    MATH_ERREXCEPT, or the bitwise OR of both. The value of math_errhandling is
-    constant for the duration of the program. It is unspecified whether
-    math_errhandling is a macro or an identifier with external linkage. If a macro
-    definition is suppressed or a program defines an identifier with the name
-    math_errhandling, the behavior is undefined.               If the expression
-    math_errhandling & MATH_ERREXCEPT can be nonzero, the implementation
-    shall define the macros FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in
-    <fenv.h>.
-    7.12.1 Treatment of error conditions
-1   The behavior of each of the functions in <math.h> is specified for all representable
-    values of its input arguments, except where stated otherwise. Each function shall execute
-    as if it were a single operation without raising SIGFPE and without generating any of the
-    exceptions ''invalid'', ''divide-by-zero'', or ''overflow'' except to reflect the result of the
-    function.
-2   For all functions, a domain error occurs if an input argument is outside the domain over
-    which the mathematical function is defined. The description of each function lists any
-    required domain errors; an implementation may define additional domain errors, provided
-    that such errors are consistent with the mathematical definition of the function.226) On a
-    domain error, the function returns an implementation-defined value; if the integer
-    expression math_errhandling & MATH_ERRNO is nonzero, the integer expression
-    errno acquires the value EDOM; if the integer expression math_errhandling &
-    MATH_ERREXCEPT is nonzero, the ''invalid'' floating-point exception is raised.
-3   Similarly, a pole error (also known as a singularity or infinitary) occurs if the
-    mathematical function has an exact infinite result as the finite input argument(s) are
-    approached in the limit (for example, log(0.0)). The description of each function lists
-    any required pole errors; an implementation may define additional pole errors, provided
-    that such errors are consistent with the mathematical definition of the function. On a pole
-    error, the function returns an implementation-defined value; if the integer expression
-
-
-    226) In an implementation that supports infinities, this allows an infinity as an argument to be a domain
-         error if the mathematical domain of the function does not include the infinity.
-
-[page 231] (Contents)
-
-    math_errhandling & MATH_ERRNO is nonzero, the integer expression errno
-    acquires the value ERANGE; if the integer expression math_errhandling &
-    MATH_ERREXCEPT is nonzero, the ''divide-by-zero'' floating-point exception is raised.
-4   Likewise, a range error occurs if the mathematical result of the function cannot be
-    represented in an object of the specified type, due to extreme magnitude.
-5   A floating result overflows if the magnitude of the mathematical result is finite but so
-    large that the mathematical result cannot be represented without extraordinary roundoff
-    error in an object of the specified type. If a floating result overflows and default rounding
-    is in effect, then the function returns the value of the macro HUGE_VAL, HUGE_VALF, or
-    HUGE_VALL according to the return type, with the same sign as the correct value of the
-    function; if the integer expression math_errhandling & MATH_ERRNO is nonzero,
-    the integer expression errno acquires the value ERANGE; if the integer expression
-    math_errhandling & MATH_ERREXCEPT is nonzero, the ''overflow'' floating-
-    point exception is raised.
-6   The result underflows if the magnitude of the mathematical result is so small that the
-    mathematical result cannot be represented, without extraordinary roundoff error, in an
-    object of the specified type.227) If the result underflows, the function returns an
-    implementation-defined value whose magnitude is no greater than the smallest
-    normalized positive number in the specified type; if the integer expression
-    math_errhandling & MATH_ERRNO is nonzero, whether errno acquires the
-    value    ERANGE       is    implementation-defined;     if   the  integer   expression
-    math_errhandling & MATH_ERREXCEPT is nonzero, whether the ''underflow''
-    floating-point exception is raised is implementation-defined.
-7   If a domain, pole, or range error occurs and the integer expression
-    math_errhandling & MATH_ERRNO is zero,228) then errno shall either be set to
-    the value corresponding to the error or left unmodified. If no such error occurs, errno
-    shall be left unmodified regardless of the setting of math_errhandling.
-
-
-
-
-    227) The term underflow here is intended to encompass both ''gradual underflow'' as in IEC 60559 and
-         also ''flush-to-zero'' underflow.
-    228) Math errors are being indicated by the floating-point exception flags rather than by errno.
-
-[page 232] (Contents)
-
-    7.12.2 The FP_CONTRACT pragma
-    Synopsis
-1            #include <math.h>
-             #pragma STDC FP_CONTRACT on-off-switch
-    Description
-2   The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the
-    state is ''off'') the implementation to contract expressions (6.5). Each pragma can occur
-    either outside external declarations or preceding all explicit declarations and statements
-    inside a compound statement. When outside external declarations, the pragma takes
-    effect from its occurrence until another FP_CONTRACT pragma is encountered, or until
-    the end of the translation unit. When inside a compound statement, the pragma takes
-    effect from its occurrence until another FP_CONTRACT pragma is encountered
-    (including within a nested compound statement), or until the end of the compound
-    statement; at the end of a compound statement the state for the pragma is restored to its
-    condition just before the compound statement. If this pragma is used in any other
-    context, the behavior is undefined. The default state (''on'' or ''off'') for the pragma is
-    implementation-defined.
-    7.12.3 Classification macros
-1   In the synopses in this subclause, real-floating indicates that the argument shall be an
-    expression of real floating type.
-    7.12.3.1 The fpclassify macro
-    Synopsis
-1            #include <math.h>
-             int fpclassify(real-floating x);
-    Description
-2   The fpclassify macro classifies its argument value as NaN, infinite, normal,
-    subnormal, zero, or into another implementation-defined category. First, an argument
-    represented in a format wider than its semantic type is converted to its semantic type.
-    Then classification is based on the type of the argument.229)
-    Returns
-3   The fpclassify macro returns the value of the number classification macro
-    appropriate to the value of its argument.
-
-
-    229) Since an expression can be evaluated with more range and precision than its type has, it is important to
-         know the type that classification is based on. For example, a normal long double value might
-         become subnormal when converted to double, and zero when converted to float.
-
-[page 233] (Contents)
-
-    7.12.3.2 The isfinite macro
-    Synopsis
-1           #include <math.h>
-            int isfinite(real-floating x);
-    Description
-2   The isfinite macro determines whether its argument has a finite value (zero,
-    subnormal, or normal, and not infinite or NaN). First, an argument represented in a
-    format wider than its semantic type is converted to its semantic type. Then determination
-    is based on the type of the argument.
-    Returns
-3   The isfinite macro returns a nonzero value if and only if its argument has a finite
-    value.
-    7.12.3.3 The isinf macro
-    Synopsis
-1           #include <math.h>
-            int isinf(real-floating x);
-    Description
-2   The isinf macro determines whether its argument value is an infinity (positive or
-    negative). First, an argument represented in a format wider than its semantic type is
-    converted to its semantic type. Then determination is based on the type of the argument.
-    Returns
-3   The isinf macro returns a nonzero value if and only if its argument has an infinite
-    value.
-    7.12.3.4 The isnan macro
-    Synopsis
-1           #include <math.h>
-            int isnan(real-floating x);
-    Description
-2   The isnan macro determines whether its argument value is a NaN. First, an argument
-    represented in a format wider than its semantic type is converted to its semantic type.
-    Then determination is based on the type of the argument.230)
-
-
-    230) For the isnan macro, the type for determination does not matter unless the implementation supports
-         NaNs in the evaluation type but not in the semantic type.
-
-[page 234] (Contents)
-
-    Returns
-3   The isnan macro returns a nonzero value if and only if its argument has a NaN value.
-    7.12.3.5 The isnormal macro
-    Synopsis
-1           #include <math.h>
-            int isnormal(real-floating x);
-    Description
-2   The isnormal macro determines whether its argument value is normal (neither zero,
-    subnormal, infinite, nor NaN). First, an argument represented in a format wider than its
-    semantic type is converted to its semantic type. Then determination is based on the type
-    of the argument.
-    Returns
-3   The isnormal macro returns a nonzero value if and only if its argument has a normal
-    value.
-    7.12.3.6 The signbit macro
-    Synopsis
-1           #include <math.h>
-            int signbit(real-floating x);
-    Description
-2   The signbit macro determines whether the sign of its argument value is negative.231)
-    Returns
-3   The signbit macro returns a nonzero value if and only if the sign of its argument value
-    is negative.
-
-
-
-
-    231) The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
-         unsigned, it is treated as positive.
-
-[page 235] (Contents)
-
-    7.12.4 Trigonometric functions
-    7.12.4.1 The acos functions
-    Synopsis
-1          #include <math.h>
-           double acos(double x);
-           float acosf(float x);
-           long double acosl(long double x);
-    Description
-2   The acos functions compute the principal value of the arc cosine of x. A domain error
-    occurs for arguments not in the interval [-1, +1].
-    Returns
-3   The acos functions return arccos x in the interval [0, pi ] radians.
-    7.12.4.2 The asin functions
-    Synopsis
-1          #include <math.h>
-           double asin(double x);
-           float asinf(float x);
-           long double asinl(long double x);
-    Description
-2   The asin functions compute the principal value of the arc sine of x. A domain error
-    occurs for arguments not in the interval [-1, +1].
-    Returns
-3   The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
-    7.12.4.3 The atan functions
-    Synopsis
-1          #include <math.h>
-           double atan(double x);
-           float atanf(float x);
-           long double atanl(long double x);
-    Description
-2   The atan functions compute the principal value of the arc tangent of x.
-
-
-
-
-[page 236] (Contents)
-
-    Returns
-3   The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
-    7.12.4.4 The atan2 functions
-    Synopsis
-1           #include <math.h>
-            double atan2(double y, double x);
-            float atan2f(float y, float x);
-            long double atan2l(long double y, long double x);
-    Description
-2   The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
-    arguments to determine the quadrant of the return value. A domain error may occur if
-    both arguments are zero.
-    Returns
-3   The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
-    7.12.4.5 The cos functions
-    Synopsis
-1           #include <math.h>
-            double cos(double x);
-            float cosf(float x);
-            long double cosl(long double x);
-    Description
-2   The cos functions compute the cosine of x (measured in radians).
-    Returns
-3   The cos functions return cos x.
-    7.12.4.6 The sin functions
-    Synopsis
-1           #include <math.h>
-            double sin(double x);
-            float sinf(float x);
-            long double sinl(long double x);
-    Description
-2   The sin functions compute the sine of x (measured in radians).
-
-
-
-[page 237] (Contents)
-
-    Returns
-3   The sin functions return sin x.
-    7.12.4.7 The tan functions
-    Synopsis
-1          #include <math.h>
-           double tan(double x);
-           float tanf(float x);
-           long double tanl(long double x);
-    Description
-2   The tan functions return the tangent of x (measured in radians).
-    Returns
-3   The tan functions return tan x.
-    7.12.5 Hyperbolic functions
-    7.12.5.1 The acosh functions
-    Synopsis
-1          #include <math.h>
-           double acosh(double x);
-           float acoshf(float x);
-           long double acoshl(long double x);
-    Description
-2   The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
-    error occurs for arguments less than 1.
-    Returns
-3   The acosh functions return arcosh x in the interval [0, +(inf)].
-    7.12.5.2 The asinh functions
-    Synopsis
-1          #include <math.h>
-           double asinh(double x);
-           float asinhf(float x);
-           long double asinhl(long double x);
-    Description
-2   The asinh functions compute the arc hyperbolic sine of x.
-
-
-[page 238] (Contents)
-
-    Returns
-3   The asinh functions return arsinh x.
-    7.12.5.3 The atanh functions
-    Synopsis
-1           #include <math.h>
-            double atanh(double x);
-            float atanhf(float x);
-            long double atanhl(long double x);
-    Description
-2   The atanh functions compute the arc hyperbolic tangent of x. A domain error occurs
-    for arguments not in the interval [-1, +1]. A pole error may occur if the argument equals
-    -1 or +1.
-    Returns
-3   The atanh functions return artanh x.
-    7.12.5.4 The cosh functions
-    Synopsis
-1           #include <math.h>
-            double cosh(double x);
-            float coshf(float x);
-            long double coshl(long double x);
-    Description
-2   The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
-    magnitude of x is too large.
-    Returns
-3   The cosh functions return cosh x.
-    7.12.5.5 The sinh functions
-    Synopsis
-1           #include <math.h>
-            double sinh(double x);
-            float sinhf(float x);
-            long double sinhl(long double x);
-    Description
-2   The sinh functions compute the hyperbolic sine of x. A range error occurs if the
-    magnitude of x is too large.
-[page 239] (Contents)
-
-    Returns
-3   The sinh functions return sinh x.
-    7.12.5.6 The tanh functions
-    Synopsis
-1          #include <math.h>
-           double tanh(double x);
-           float tanhf(float x);
-           long double tanhl(long double x);
-    Description
-2   The tanh functions compute the hyperbolic tangent of x.
-    Returns
-3   The tanh functions return tanh x.
-    7.12.6 Exponential and logarithmic functions
-    7.12.6.1 The exp functions
-    Synopsis
-1          #include <math.h>
-           double exp(double x);
-           float expf(float x);
-           long double expl(long double x);
-    Description
-2   The exp functions compute the base-e exponential of x. A range error occurs if the
-    magnitude of x is too large.
-    Returns
-3   The exp functions return ex .
-    7.12.6.2 The exp2 functions
-    Synopsis
-1          #include <math.h>
-           double exp2(double x);
-           float exp2f(float x);
-           long double exp2l(long double x);
-    Description
-2   The exp2 functions compute the base-2 exponential of x. A range error occurs if the
-    magnitude of x is too large.
-
-[page 240] (Contents)
-
-    Returns
-3   The exp2 functions return 2x .
-    7.12.6.3 The expm1 functions
-    Synopsis
-1           #include <math.h>
-            double expm1(double x);
-            float expm1f(float x);
-            long double expm1l(long double x);
-    Description
-2   The expm1 functions compute the base-e exponential of the argument, minus 1. A range
-    error occurs if x is too large.232)
-    Returns
-3   The expm1 functions return ex - 1.
-    7.12.6.4 The frexp functions
-    Synopsis
-1           #include <math.h>
-            double frexp(double value, int *exp);
-            float frexpf(float value, int *exp);
-            long double frexpl(long double value, int *exp);
-    Description
-2   The frexp functions break a floating-point number into a normalized fraction and an
-    integral power of 2. They store the integer in the int object pointed to by exp.
-    Returns
-3   If value is not a floating-point number or if the integral power of 2 is outside the range
-    of int, the results are unspecified. Otherwise, the frexp functions return the value x,
-    such that x has a magnitude in the interval [1/2, 1) or zero, and value equals x x 2*exp .
-    If value is zero, both parts of the result are zero.
-
-
-
-
-    232) For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
-
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-
-    7.12.6.5 The ilogb functions
-    Synopsis
-1          #include <math.h>
-           int ilogb(double x);
-           int ilogbf(float x);
-           int ilogbl(long double x);
-    Description
-2   The ilogb functions extract the exponent of x as a signed int value. If x is zero they
-    compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is
-    a NaN they compute the value FP_ILOGBNAN; otherwise, they are equivalent to calling
-    the corresponding logb function and casting the returned value to type int. A domain
-    error or range error may occur if x is zero, infinite, or NaN. If the correct value is outside
-    the range of the return type, the numeric result is unspecified.
-    Returns
-3   The ilogb functions return the exponent of x as a signed int value.
-    Forward references: the logb functions (7.12.6.11).
-    7.12.6.6 The ldexp functions
-    Synopsis
-1          #include <math.h>
-           double ldexp(double x, int exp);
-           float ldexpf(float x, int exp);
-           long double ldexpl(long double x, int exp);
-    Description
-2   The ldexp functions multiply a floating-point number by an integral power of 2. A
-    range error may occur.
-    Returns
-3   The ldexp functions return x x 2exp .
-    7.12.6.7 The log functions
-    Synopsis
-1          #include <math.h>
-           double log(double x);
-           float logf(float x);
-           long double logl(long double x);
-
-
-
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-
-    Description
-2   The log functions compute the base-e (natural) logarithm of x. A domain error occurs if
-    the argument is negative. A pole error may occur if the argument is zero.
-    Returns
-3   The log functions return loge x.
-    7.12.6.8 The log10 functions
-    Synopsis
-1           #include <math.h>
-            double log10(double x);
-            float log10f(float x);
-            long double log10l(long double x);
-    Description
-2   The log10 functions compute the base-10 (common) logarithm of x. A domain error
-    occurs if the argument is negative. A pole error may occur if the argument is zero.
-    Returns
-3   The log10 functions return log10 x.
-    7.12.6.9 The log1p functions
-    Synopsis
-1           #include <math.h>
-            double log1p(double x);
-            float log1pf(float x);
-            long double log1pl(long double x);
-    Description
-2   The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.233)
-    A domain error occurs if the argument is less than -1. A pole error may occur if the
-    argument equals -1.
-    Returns
-3   The log1p functions return loge (1 + x).
-
-
-
-
-    233) For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
-
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-
-    7.12.6.10 The log2 functions
-    Synopsis
-1          #include <math.h>
-           double log2(double x);
-           float log2f(float x);
-           long double log2l(long double x);
-    Description
-2   The log2 functions compute the base-2 logarithm of x. A domain error occurs if the
-    argument is less than zero. A pole error may occur if the argument is zero.
-    Returns
-3   The log2 functions return log2 x.
-    7.12.6.11 The logb functions
-    Synopsis
-1          #include <math.h>
-           double logb(double x);
-           float logbf(float x);
-           long double logbl(long double x);
-    Description
-2   The logb functions extract the exponent of x, as a signed integer value in floating-point
-    format. If x is subnormal it is treated as though it were normalized; thus, for positive
-    finite x,
-          1 <= x x FLT_RADIX-logb(x) < FLT_RADIX
-    A domain error or pole error may occur if the argument is zero.
-    Returns
-3   The logb functions return the signed exponent of x.
-    7.12.6.12 The modf functions
-    Synopsis
-1          #include <math.h>
-           double modf(double value, double *iptr);
-           float modff(float value, float *iptr);
-           long double modfl(long double value, long double *iptr);
-    Description
-2   The modf functions break the argument value into integral and fractional parts, each of
-    which has the same type and sign as the argument. They store the integral part (in
-[page 244] (Contents)
-
-    floating-point format) in the object pointed to by iptr.
-    Returns
-3   The modf functions return the signed fractional part of value.
-    7.12.6.13 The scalbn and scalbln functions
-    Synopsis
-1           #include <math.h>
-            double scalbn(double x, int n);
-            float scalbnf(float x, int n);
-            long double scalbnl(long double x, int n);
-            double scalbln(double x, long int n);
-            float scalblnf(float x, long int n);
-            long double scalblnl(long double x, long int n);
-    Description
-2   The scalbn and scalbln functions compute x x FLT_RADIXn efficiently, not
-    normally by computing FLT_RADIXn explicitly. A range error may occur.
-    Returns
-3   The scalbn and scalbln functions return x x FLT_RADIXn .
-    7.12.7 Power and absolute-value functions
-    7.12.7.1 The cbrt functions
-    Synopsis
-1           #include <math.h>
-            double cbrt(double x);
-            float cbrtf(float x);
-            long double cbrtl(long double x);
-    Description
-2   The cbrt functions compute the real cube root of x.
-    Returns
-3   The cbrt functions return x1/3 .
-
-
-
-
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-
-    7.12.7.2 The fabs functions
-    Synopsis
-1          #include <math.h>
-           double fabs(double x);
-           float fabsf(float x);
-           long double fabsl(long double x);
-    Description
-2   The fabs functions compute the absolute value of a floating-point number x.
-    Returns
-3   The fabs functions return | x |.
-    7.12.7.3 The hypot functions
-    Synopsis
-1          #include <math.h>
-           double hypot(double x, double y);
-           float hypotf(float x, float y);
-           long double hypotl(long double x, long double y);
-    Description
-2   The hypot functions compute the square root of the sum of the squares of x and y,
-    without undue overflow or underflow. A range error may occur.
-3   Returns
-4   The hypot functions return sqrt:x2 + y2 .
-                               -
-                               -----
-    7.12.7.4 The pow functions
-    Synopsis
-1          #include <math.h>
-           double pow(double x, double y);
-           float powf(float x, float y);
-           long double powl(long double x, long double y);
-    Description
-2   The pow functions compute x raised to the power y. A domain error occurs if x is finite
-    and negative and y is finite and not an integer value. A range error may occur. A domain
-    error may occur if x is zero and y is zero. A domain error or pole error may occur if x is
-    zero and y is less than zero.
-
-
-
-
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-
-    Returns
-3   The pow functions return xy .
-    7.12.7.5 The sqrt functions
-    Synopsis
-1           #include <math.h>
-            double sqrt(double x);
-            float sqrtf(float x);
-            long double sqrtl(long double x);
-    Description
-2   The sqrt functions compute the nonnegative square root of x. A domain error occurs if
-    the argument is less than zero.
-    Returns
-3   The sqrt functions return sqrt:x.
-                              -
-                              -
-    7.12.8 Error and gamma functions
-    7.12.8.1 The erf functions
-    Synopsis
-1           #include <math.h>
-            double erf(double x);
-            float erff(float x);
-            long double erfl(long double x);
-    Description
-2   The erf functions compute the error function of x.
-    Returns
-3                                      2        x
-                                            (integral)       e-t dt.
-                                                      2
-    The erf functions return erf x =
-                                       sqrt:pi
-                                       -
-                                       -    0
-
-    7.12.8.2 The erfc functions
-    Synopsis
-1           #include <math.h>
-            double erfc(double x);
-            float erfcf(float x);
-            long double erfcl(long double x);
-    Description
-2   The erfc functions compute the complementary error function of x. A range error
-    occurs if x is too large.
-[page 247] (Contents)
-
-    Returns
-3                                                       2       (inf)
-                                                            (integral)       e-t dt.
-                                                                      2
-    The erfc functions return erfc x = 1 - erf x =
-                                                     sqrt:pi
-                                                     -
-                                                     -      x
-
-    7.12.8.3 The lgamma functions
-    Synopsis
-1          #include <math.h>
-           double lgamma(double x);
-           float lgammaf(float x);
-           long double lgammal(long double x);
-    Description
-2   The lgamma functions compute the natural logarithm of the absolute value of gamma of
-    x. A range error occurs if x is too large. A pole error may occur if x is a negative integer
-    or zero.
-    Returns
-3   The lgamma functions return loge | (Gamma)(x) |.
-    7.12.8.4 The tgamma functions
-    Synopsis
-1          #include <math.h>
-           double tgamma(double x);
-           float tgammaf(float x);
-           long double tgammal(long double x);
-    Description
-2   The tgamma functions compute the gamma function of x. A domain error or pole error
-    may occur if x is a negative integer or zero. A range error occurs if the magnitude of x is
-    too large and may occur if the magnitude of x is too small.
-    Returns
-3   The tgamma functions return (Gamma)(x).
-
-
-
-
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-
-    7.12.9 Nearest integer functions
-    7.12.9.1 The ceil functions
-    Synopsis
-1           #include <math.h>
-            double ceil(double x);
-            float ceilf(float x);
-            long double ceill(long double x);
-    Description
-2   The ceil functions compute the smallest integer value not less than x.
-    Returns
-3   The ceil functions return [^x^], expressed as a floating-point number.
-    7.12.9.2 The floor functions
-    Synopsis
-1           #include <math.h>
-            double floor(double x);
-            float floorf(float x);
-            long double floorl(long double x);
-    Description
-2   The floor functions compute the largest integer value not greater than x.
-    Returns
-3   The floor functions return [_x_], expressed as a floating-point number.
-    7.12.9.3 The nearbyint functions
-    Synopsis
-1           #include <math.h>
-            double nearbyint(double x);
-            float nearbyintf(float x);
-            long double nearbyintl(long double x);
-    Description
-2   The nearbyint functions round their argument to an integer value in floating-point
-    format, using the current rounding direction and without raising the ''inexact'' floating-
-    point exception.
-
-
-
-
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-
-    Returns
-3   The nearbyint functions return the rounded integer value.
-    7.12.9.4 The rint functions
-    Synopsis
-1          #include <math.h>
-           double rint(double x);
-           float rintf(float x);
-           long double rintl(long double x);
-    Description
-2   The rint functions differ from the nearbyint functions (7.12.9.3) only in that the
-    rint functions may raise the ''inexact'' floating-point exception if the result differs in
-    value from the argument.
-    Returns
-3   The rint functions return the rounded integer value.
-    7.12.9.5 The lrint and llrint functions
-    Synopsis
-1          #include <math.h>
-           long int lrint(double x);
-           long int lrintf(float x);
-           long int lrintl(long double x);
-           long long int llrint(double x);
-           long long int llrintf(float x);
-           long long int llrintl(long double x);
-    Description
-2   The lrint and llrint functions round their argument to the nearest integer value,
-    rounding according to the current rounding direction. If the rounded value is outside the
-    range of the return type, the numeric result is unspecified and a domain error or range
-    error may occur.
-    Returns
-3   The lrint and llrint functions return the rounded integer value.
-
-
-
-
-[page 250] (Contents)
-
-    7.12.9.6 The round functions
-    Synopsis
-1           #include <math.h>
-            double round(double x);
-            float roundf(float x);
-            long double roundl(long double x);
-    Description
-2   The round functions round their argument to the nearest integer value in floating-point
-    format, rounding halfway cases away from zero, regardless of the current rounding
-    direction.
-    Returns
-3   The round functions return the rounded integer value.
-    7.12.9.7 The lround and llround functions
-    Synopsis
-1           #include <math.h>
-            long int lround(double x);
-            long int lroundf(float x);
-            long int lroundl(long double x);
-            long long int llround(double x);
-            long long int llroundf(float x);
-            long long int llroundl(long double x);
-    Description
-2   The lround and llround functions round their argument to the nearest integer value,
-    rounding halfway cases away from zero, regardless of the current rounding direction. If
-    the rounded value is outside the range of the return type, the numeric result is unspecified
-    and a domain error or range error may occur.
-    Returns
-3   The lround and llround functions return the rounded integer value.
-    7.12.9.8 The trunc functions
-    Synopsis
-1           #include <math.h>
-            double trunc(double x);
-            float truncf(float x);
-            long double truncl(long double x);
-
-
-[page 251] (Contents)
-
-    Description
-2   The trunc functions round their argument to the integer value, in floating format,
-    nearest to but no larger in magnitude than the argument.
-    Returns
-3   The trunc functions return the truncated integer value.
-    7.12.10 Remainder functions
-    7.12.10.1 The fmod functions
-    Synopsis
-1            #include <math.h>
-             double fmod(double x, double y);
-             float fmodf(float x, float y);
-             long double fmodl(long double x, long double y);
-    Description
-2   The fmod functions compute the floating-point remainder of x/y.
-    Returns
-3   The fmod functions return the value x - ny, for some integer n such that, if y is nonzero,
-    the result has the same sign as x and magnitude less than the magnitude of y. If y is zero,
-    whether a domain error occurs or the fmod functions return zero is implementation-
-    defined.
-    7.12.10.2 The remainder functions
-    Synopsis
-1            #include <math.h>
-             double remainder(double x, double y);
-             float remainderf(float x, float y);
-             long double remainderl(long double x, long double y);
-    Description
-2   The remainder functions compute the remainder x REM y required by IEC 60559.234)
-
-
-
-
-    234) ''When y != 0, the remainder r = x REM y is defined regardless of the rounding mode by the
-         mathematical relation r = x - ny, where n is the integer nearest the exact value of x/y; whenever
-         | n - x/y | = 1/2, then n is even. If r = 0, its sign shall be that of x.'' This definition is applicable for
-         all implementations.
-
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-
-    Returns
-3   The remainder functions return x REM y. If y is zero, whether a domain error occurs
-    or the functions return zero is implementation defined.
-    7.12.10.3 The remquo functions
-    Synopsis
-1           #include <math.h>
-            double remquo(double x, double y, int *quo);
-            float remquof(float x, float y, int *quo);
-            long double remquol(long double x, long double y,
-                 int *quo);
-    Description
-2   The remquo functions compute the same remainder as the remainder functions. In
-    the object pointed to by quo they store a value whose sign is the sign of x/y and whose
-    magnitude is congruent modulo 2n to the magnitude of the integral quotient of x/y, where
-    n is an implementation-defined integer greater than or equal to 3.
-    Returns
-3   The remquo functions return x REM y. If y is zero, the value stored in the object
-    pointed to by quo is unspecified and whether a domain error occurs or the functions
-    return zero is implementation defined.
-    7.12.11 Manipulation functions
-    7.12.11.1 The copysign functions
-    Synopsis
-1           #include <math.h>
-            double copysign(double x, double y);
-            float copysignf(float x, float y);
-            long double copysignl(long double x, long double y);
-    Description
-2   The copysign functions produce a value with the magnitude of x and the sign of y.
-    They produce a NaN (with the sign of y) if x is a NaN. On implementations that
-    represent a signed zero but do not treat negative zero consistently in arithmetic
-    operations, the copysign functions regard the sign of zero as positive.
-    Returns
-3   The copysign functions return a value with the magnitude of x and the sign of y.
-
-
-
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-
-    7.12.11.2 The nan functions
-    Synopsis
-1           #include <math.h>
-            double nan(const char *tagp);
-            float nanf(const char *tagp);
-            long double nanl(const char *tagp);
-    Description
-2   The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char-
-    sequence)",     (char**)       NULL); the call nan("") is equivalent to
-    strtod("NAN()", (char**) NULL). If tagp does not point to an n-char
-    sequence or an empty string, the call is equivalent to strtod("NAN", (char**)
-    NULL). Calls to nanf and nanl are equivalent to the corresponding calls to strtof
-    and strtold.
-    Returns
-3   The nan functions return a quiet NaN, if available, with content indicated through tagp.
-    If the implementation does not support quiet NaNs, the functions return zero.
-    Forward references: the strtod, strtof, and strtold functions (7.22.1.3).
-    7.12.11.3 The nextafter functions
-    Synopsis
-1           #include <math.h>
-            double nextafter(double x, double y);
-            float nextafterf(float x, float y);
-            long double nextafterl(long double x, long double y);
-    Description
-2   The nextafter functions determine the next representable value, in the type of the
-    function, after x in the direction of y, where x and y are first converted to the type of the
-    function.235) The nextafter functions return y if x equals y. A range error may occur
-    if the magnitude of x is the largest finite value representable in the type and the result is
-    infinite or not representable in the type.
-    Returns
-3   The nextafter functions return the next representable value in the specified format
-    after x in the direction of y.
-
-
-    235) The argument values are converted to the type of the function, even by a macro implementation of the
-         function.
-
-[page 254] (Contents)
-
-    7.12.11.4 The nexttoward functions
-    Synopsis
-1           #include <math.h>
-            double nexttoward(double x, long double y);
-            float nexttowardf(float x, long double y);
-            long double nexttowardl(long double x, long double y);
-    Description
-2   The nexttoward functions are equivalent to the nextafter functions except that the
-    second parameter has type long double and the functions return y converted to the
-    type of the function if x equals y.236)
-    7.12.12 Maximum, minimum, and positive difference functions
-    7.12.12.1 The fdim functions
-    Synopsis
-1           #include <math.h>
-            double fdim(double x, double y);
-            float fdimf(float x, float y);
-            long double fdiml(long double x, long double y);
-    Description
-2   The fdim functions determine the positive difference between their arguments:
-          {x - y if x > y
-          {
-          {+0     if x <= y
-    A range error may occur.
-    Returns
-3   The fdim functions return the positive difference value.
-    7.12.12.2 The fmax functions
-    Synopsis
-1           #include <math.h>
-            double fmax(double x, double y);
-            float fmaxf(float x, float y);
-            long double fmaxl(long double x, long double y);
-
-
-
-    236) The result of the nexttoward functions is determined in the type of the function, without loss of
-         range or precision in a floating second argument.
-
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-
-    Description
-2   The fmax functions determine the maximum numeric value of their arguments.237)
-    Returns
-3   The fmax functions return the maximum numeric value of their arguments.
-    7.12.12.3 The fmin functions
-    Synopsis
-1           #include <math.h>
-            double fmin(double x, double y);
-            float fminf(float x, float y);
-            long double fminl(long double x, long double y);
-    Description
-2   The fmin functions determine the minimum numeric value of their arguments.238)
-    Returns
-3   The fmin functions return the minimum numeric value of their arguments.
-    7.12.13 Floating multiply-add
-    7.12.13.1 The fma functions
-    Synopsis
-1           #include <math.h>
-            double fma(double x, double y, double z);
-            float fmaf(float x, float y, float z);
-            long double fmal(long double x, long double y,
-                 long double z);
-    Description
-2   The fma functions compute (x x y) + z, rounded as one ternary operation: they compute
-    the value (as if) to infinite precision and round once to the result format, according to the
-    current rounding mode. A range error may occur.
-    Returns
-3   The fma functions return (x x y) + z, rounded as one ternary operation.
-
-
-
-
-    237) NaN arguments are treated as missing data: if one argument is a NaN and the other numeric, then the
-         fmax functions choose the numeric value. See F.10.9.2.
-    238) The fmin functions are analogous to the fmax functions in their treatment of NaNs.
-
-[page 256] (Contents)
-
-    7.12.14 Comparison macros
-1   The relational and equality operators support the usual mathematical relationships
-    between numeric values. For any ordered pair of numeric values exactly one of the
-    relationships -- less, greater, and equal -- is true. Relational operators may raise the
-    ''invalid'' floating-point exception when argument values are NaNs. For a NaN and a
-    numeric value, or for two NaNs, just the unordered relationship is true.239) The following
-    subclauses provide macros that are quiet (non floating-point exception raising) versions
-    of the relational operators, and other comparison macros that facilitate writing efficient
-    code that accounts for NaNs without suffering the ''invalid'' floating-point exception. In
-    the synopses in this subclause, real-floating indicates that the argument shall be an
-    expression of real floating type (both arguments need not have the same type).240)
-    7.12.14.1 The isgreater macro
-    Synopsis
-1            #include <math.h>
-             int isgreater(real-floating x, real-floating y);
-    Description
-2   The isgreater macro determines whether its first argument is greater than its second
-    argument. The value of isgreater(x, y) is always equal to (x) > (y); however,
-    unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point
-    exception when x and y are unordered.
-    Returns
-3   The isgreater macro returns the value of (x) > (y).
-    7.12.14.2 The isgreaterequal macro
-    Synopsis
-1            #include <math.h>
-             int isgreaterequal(real-floating x, real-floating y);
-    Description
-2   The isgreaterequal macro determines whether its first argument is greater than or
-    equal to its second argument. The value of isgreaterequal(x, y) is always equal
-    to (x) >= (y); however, unlike (x) >= (y), isgreaterequal(x, y) does
-
-
-    239) IEC 60559 requires that the built-in relational operators raise the ''invalid'' floating-point exception if
-         the operands compare unordered, as an error indicator for programs written without consideration of
-         NaNs; the result in these cases is false.
-    240) Whether an argument represented in a format wider than its semantic type is converted to the semantic
-         type is unspecified.
-
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-
-    not raise the ''invalid'' floating-point exception when x and y are unordered.
-    Returns
-3   The isgreaterequal macro returns the value of (x) >= (y).
-    7.12.14.3 The isless macro
-    Synopsis
-1          #include <math.h>
-           int isless(real-floating x, real-floating y);
-    Description
-2   The isless macro determines whether its first argument is less than its second
-    argument. The value of isless(x, y) is always equal to (x) < (y); however,
-    unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point
-    exception when x and y are unordered.
-    Returns
-3   The isless macro returns the value of (x) < (y).
-    7.12.14.4 The islessequal macro
-    Synopsis
-1          #include <math.h>
-           int islessequal(real-floating x, real-floating y);
-    Description
-2   The islessequal macro determines whether its first argument is less than or equal to
-    its second argument. The value of islessequal(x, y) is always equal to
-    (x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise
-    the ''invalid'' floating-point exception when x and y are unordered.
-    Returns
-3   The islessequal macro returns the value of (x) <= (y).
-    7.12.14.5 The islessgreater macro
-    Synopsis
-1          #include <math.h>
-           int islessgreater(real-floating x, real-floating y);
-    Description
-2   The islessgreater macro determines whether its first argument is less than or
-    greater than its second argument. The islessgreater(x, y) macro is similar to
-    (x) < (y) || (x) > (y); however, islessgreater(x, y) does not raise
-
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-
-    the ''invalid'' floating-point exception when x and y are unordered (nor does it evaluate x
-    and y twice).
-    Returns
-3   The islessgreater macro returns the value of (x) < (y) || (x) > (y).
-    7.12.14.6 The isunordered macro
-    Synopsis
-1           #include <math.h>
-            int isunordered(real-floating x, real-floating y);
-    Description
-2   The isunordered macro determines whether its arguments are unordered.
-    Returns
-3   The isunordered macro returns 1 if its arguments are unordered and 0 otherwise.
-
-
-
-
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-
-    7.13 Nonlocal jumps <setjmp.h>
-1   The header <setjmp.h> defines the macro setjmp, and declares one function and
-    one type, for bypassing the normal function call and return discipline.241)
-2   The type declared is
-            jmp_buf
-    which is an array type suitable for holding the information needed to restore a calling
-    environment. The environment of a call to the setjmp macro consists of information
-    sufficient for a call to the longjmp function to return execution to the correct block and
-    invocation of that block, were it called recursively. It does not include the state of the
-    floating-point status flags, of open files, or of any other component of the abstract
-    machine.
-3   It is unspecified whether setjmp is a macro or an identifier declared with external
-    linkage. If a macro definition is suppressed in order to access an actual function, or a
-    program defines an external identifier with the name setjmp, the behavior is undefined.
-    7.13.1 Save calling environment
-    7.13.1.1 The setjmp macro
-    Synopsis
-1           #include <setjmp.h>
-            int setjmp(jmp_buf env);
-    Description
-2   The setjmp macro saves its calling environment in its jmp_buf argument for later use
-    by the longjmp function.
-    Returns
-3   If the return is from a direct invocation, the setjmp macro returns the value zero. If the
-    return is from a call to the longjmp function, the setjmp macro returns a nonzero
-    value.
-    Environmental limits
-4   An invocation of the setjmp macro shall appear only in one of the following contexts:
-    -- the entire controlling expression of a selection or iteration statement;
-    -- one operand of a relational or equality operator with the other operand an integer
-      constant expression, with the resulting expression being the entire controlling
-
-
-    241) These functions are useful for dealing with unusual conditions encountered in a low-level function of
-         a program.
-
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-
-        expression of a selection or iteration statement;
-    -- the operand of a unary ! operator with the resulting expression being the entire
-      controlling expression of a selection or iteration statement; or
-    -- the entire expression of an expression statement (possibly cast to void).
-5   If the invocation appears in any other context, the behavior is undefined.
-    7.13.2 Restore calling environment
-    7.13.2.1 The longjmp function
-    Synopsis
-1            #include <setjmp.h>
-             _Noreturn void longjmp(jmp_buf env, int val);
-    Description
-2   The longjmp function restores the environment saved by the most recent invocation of
-    the setjmp macro in the same invocation of the program with the corresponding
-    jmp_buf argument. If there has been no such invocation, or if the function containing
-    the invocation of the setjmp macro has terminated execution242) in the interim, or if the
-    invocation of the setjmp macro was within the scope of an identifier with variably
-    modified type and execution has left that scope in the interim, the behavior is undefined.
-3   All accessible objects have values, and all other components of the abstract machine243)
-    have state, as of the time the longjmp function was called, except that the values of
-    objects of automatic storage duration that are local to the function containing the
-    invocation of the corresponding setjmp macro that do not have volatile-qualified type
-    and have been changed between the setjmp invocation and longjmp call are
-    indeterminate.
-    Returns
-4   After longjmp is completed, program execution continues as if the corresponding
-    invocation of the setjmp macro had just returned the value specified by val. The
-    longjmp function cannot cause the setjmp macro to return the value 0; if val is 0,
-    the setjmp macro returns the value 1.
-5   EXAMPLE The longjmp function that returns control back to the point of the setjmp invocation
-    might cause memory associated with a variable length array object to be squandered.
-
-
-
-
-    242) For example, by executing a return statement or because another longjmp call has caused a
-         transfer to a setjmp invocation in a function earlier in the set of nested calls.
-    243) This includes, but is not limited to, the floating-point status flags and the state of open files.
-
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-
-      #include <setjmp.h>
-      jmp_buf buf;
-      void g(int n);
-      void h(int n);
-      int n = 6;
-      void f(void)
-      {
-            int x[n];             // valid: f is not terminated
-            setjmp(buf);
-            g(n);
-      }
-      void g(int n)
-      {
-            int a[n];             // a may remain allocated
-            h(n);
-      }
-      void h(int n)
-      {
-            int b[n];             // b may remain allocated
-            longjmp(buf, 2);      // might cause memory loss
-      }
-
-
-
-
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-
-    7.14 Signal handling <signal.h>
-1   The header <signal.h> declares a type and two functions and defines several macros,
-    for handling various signals (conditions that may be reported during program execution).
-2   The type defined is
-             sig_atomic_t
-    which is the (possibly volatile-qualified) integer type of an object that can be accessed as
-    an atomic entity, even in the presence of asynchronous interrupts.
-3   The macros defined are
-             SIG_DFL
-             SIG_ERR
-             SIG_IGN
-    which expand to constant expressions with distinct values that have type compatible with
-    the second argument to, and the return value of, the signal function, and whose values
-    compare unequal to the address of any declarable function; and the following, which
-    expand to positive integer constant expressions with type int and distinct values that are
-    the signal numbers, each corresponding to the specified condition:
-             SIGABRT abnormal termination, such as is initiated by the abort function
-             SIGFPE        an erroneous arithmetic operation, such as zero divide or an operation
-                           resulting in overflow
-             SIGILL        detection of an invalid function image, such as an invalid instruction
-             SIGINT        receipt of an interactive attention signal
-             SIGSEGV an invalid access to storage
-             SIGTERM a termination request sent to the program
-4   An implementation need not generate any of these signals, except as a result of explicit
-    calls to the raise function. Additional signals and pointers to undeclarable functions,
-    with macro definitions beginning, respectively, with the letters SIG and an uppercase
-    letter or with SIG_ and an uppercase letter,244) may also be specified by the
-    implementation. The complete set of signals, their semantics, and their default handling
-    is implementation-defined; all signal numbers shall be positive.
-
-
-
-
-    244) See ''future library directions'' (7.30.6). The names of the signal numbers reflect the following terms
-         (respectively): abort, floating-point exception, illegal instruction, interrupt, segmentation violation,
-         and termination.
-
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-
-    7.14.1 Specify signal handling
-    7.14.1.1 The signal function
-    Synopsis
-1           #include <signal.h>
-            void (*signal(int sig, void (*func)(int)))(int);
-    Description
-2   The signal function chooses one of three ways in which receipt of the signal number
-    sig is to be subsequently handled. If the value of func is SIG_DFL, default handling
-    for that signal will occur. If the value of func is SIG_IGN, the signal will be ignored.
-    Otherwise, func shall point to a function to be called when that signal occurs. An
-    invocation of such a function because of a signal, or (recursively) of any further functions
-    called by that invocation (other than functions in the standard library), is called a signal
-    handler.
-3   When a signal occurs and func points to a function, it is implementation-defined
-    whether the equivalent of signal(sig, SIG_DFL); is executed or the
-    implementation prevents some implementation-defined set of signals (at least including
-    sig) from occurring until the current signal handling has completed; in the case of
-    SIGILL, the implementation may alternatively define that no action is taken. Then the
-    equivalent of (*func)(sig); is executed. If and when the function returns, if the
-    value of sig is SIGFPE, SIGILL, SIGSEGV, or any other implementation-defined
-    value corresponding to a computational exception, the behavior is undefined; otherwise
-    the program will resume execution at the point it was interrupted.
-4   If the signal occurs as the result of calling the abort or raise function, the signal
-    handler shall not call the raise function.
-5   If the signal occurs other than as the result of calling the abort or raise function, the
-    behavior is undefined if the signal handler refers to any object with static or thread
-    storage duration other than by assigning a value to an object declared as volatile
-    sig_atomic_t, or the signal handler calls any function in the standard library other
-    than the abort function, the _Exit function, the quick_exit function, or the
-    signal function with the first argument equal to the signal number corresponding to the
-    signal that caused the invocation of the handler. Furthermore, if such a call to the
-    signal function results in a SIG_ERR return, the value of errno is indeterminate.245)
-6   At program startup, the equivalent of
-            signal(sig, SIG_IGN);
-
-
-    245) If any signal is generated by an asynchronous signal handler, the behavior is undefined.
-
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-
-    may be executed for some signals selected in an implementation-defined manner; the
-    equivalent of
-            signal(sig, SIG_DFL);
-    is executed for all other signals defined by the implementation.
-7   The implementation shall behave as if no library function calls the signal function.
-    Returns
-8   If the request can be honored, the signal function returns the value of func for the
-    most recent successful call to signal for the specified signal sig. Otherwise, a value of
-    SIG_ERR is returned and a positive value is stored in errno.
-    Forward references: the abort function (7.22.4.1), the exit function (7.22.4.4), the
-    _Exit function (7.22.4.5), the quick_exit function (7.22.4.7).
-    7.14.2 Send signal
-    7.14.2.1 The raise function
-    Synopsis
-1           #include <signal.h>
-            int raise(int sig);
-    Description
-2   The raise function carries out the actions described in 7.14.1.1 for the signal sig. If a
-    signal handler is called, the raise function shall not return until after the signal handler
-    does.
-    Returns
-3   The raise function returns zero if successful, nonzero if unsuccessful.
-
-
-
-
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-
-    7.15 Alignment <stdalign.h>
-1   The header <stdalign.h> defines two macros.
-2   The macro
-           alignas
-    expands to _Alignas.
-3   The remaining macro is suitable for use in #if preprocessing directives. It is
-           __alignas_is_defined
-    which expands to the integer constant 1.
-
-
-
-
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-
-    7.16 Variable arguments <stdarg.h>
-1   The header <stdarg.h> declares a type and defines four macros, for advancing
-    through a list of arguments whose number and types are not known to the called function
-    when it is translated.
-2   A function may be called with a variable number of arguments of varying types. As
-    described in 6.9.1, its parameter list contains one or more parameters. The rightmost
-    parameter plays a special role in the access mechanism, and will be designated parmN in
-    this description.
-3   The type declared is
-            va_list
-    which is a complete object type suitable for holding information needed by the macros
-    va_start, va_arg, va_end, and va_copy. If access to the varying arguments is
-    desired, the called function shall declare an object (generally referred to as ap in this
-    subclause) having type va_list. The object ap may be passed as an argument to
-    another function; if that function invokes the va_arg macro with parameter ap, the
-    value of ap in the calling function is indeterminate and shall be passed to the va_end
-    macro prior to any further reference to ap.246)
-    7.16.1 Variable argument list access macros
-1   The va_start and va_arg macros described in this subclause shall be implemented
-    as macros, not functions. It is unspecified whether va_copy and va_end are macros or
-    identifiers declared with external linkage. If a macro definition is suppressed in order to
-    access an actual function, or a program defines an external identifier with the same name,
-    the behavior is undefined. Each invocation of the va_start and va_copy macros
-    shall be matched by a corresponding invocation of the va_end macro in the same
-    function.
-    7.16.1.1 The va_arg macro
-    Synopsis
-1           #include <stdarg.h>
-            type va_arg(va_list ap, type);
-    Description
-2   The va_arg macro expands to an expression that has the specified type and the value of
-    the next argument in the call. The parameter ap shall have been initialized by the
-    va_start or va_copy macro (without an intervening invocation of the va_end
-
-    246) It is permitted to create a pointer to a va_list and pass that pointer to another function, in which
-         case the original function may make further use of the original list after the other function returns.
-
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-
-    macro for the same ap). Each invocation of the va_arg macro modifies ap so that the
-    values of successive arguments are returned in turn. The parameter type shall be a type
-    name specified such that the type of a pointer to an object that has the specified type can
-    be obtained simply by postfixing a * to type. If there is no actual next argument, or if
-    type is not compatible with the type of the actual next argument (as promoted according
-    to the default argument promotions), the behavior is undefined, except for the following
-    cases:
-    -- one type is a signed integer type, the other type is the corresponding unsigned integer
-      type, and the value is representable in both types;
-    -- one type is pointer to void and the other is a pointer to a character type.
-    Returns
-3   The first invocation of the va_arg macro after that of the va_start macro returns the
-    value of the argument after that specified by parmN . Successive invocations return the
-    values of the remaining arguments in succession.
-    7.16.1.2 The va_copy macro
-    Synopsis
-1          #include <stdarg.h>
-           void va_copy(va_list dest, va_list src);
-    Description
-2   The va_copy macro initializes dest as a copy of src, as if the va_start macro had
-    been applied to dest followed by the same sequence of uses of the va_arg macro as
-    had previously been used to reach the present state of src. Neither the va_copy nor
-    va_start macro shall be invoked to reinitialize dest without an intervening
-    invocation of the va_end macro for the same dest.
-    Returns
-3   The va_copy macro returns no value.
-    7.16.1.3 The va_end macro
-    Synopsis
-1          #include <stdarg.h>
-           void va_end(va_list ap);
-    Description
-2   The va_end macro facilitates a normal return from the function whose variable
-    argument list was referred to by the expansion of the va_start macro, or the function
-    containing the expansion of the va_copy macro, that initialized the va_list ap. The
-    va_end macro may modify ap so that it is no longer usable (without being reinitialized
-
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-
-    by the va_start or va_copy macro). If there is no corresponding invocation of the
-    va_start or va_copy macro, or if the va_end macro is not invoked before the
-    return, the behavior is undefined.
-    Returns
-3   The va_end macro returns no value.
-    7.16.1.4 The va_start macro
-    Synopsis
-1           #include <stdarg.h>
-            void va_start(va_list ap, parmN);
-    Description
-2   The va_start macro shall be invoked before any access to the unnamed arguments.
-3   The va_start macro initializes ap for subsequent use by the va_arg and va_end
-    macros. Neither the va_start nor va_copy macro shall be invoked to reinitialize ap
-    without an intervening invocation of the va_end macro for the same ap.
-4   The parameter parmN is the identifier of the rightmost parameter in the variable
-    parameter list in the function definition (the one just before the , ...). If the parameter
-    parmN is declared with the register storage class, with a function or array type, or
-    with a type that is not compatible with the type that results after application of the default
-    argument promotions, the behavior is undefined.
-    Returns
-5   The va_start macro returns no value.
-6   EXAMPLE 1 The function f1 gathers into an array a list of arguments that are pointers to strings (but not
-    more than MAXARGS arguments), then passes the array as a single argument to function f2. The number of
-    pointers is specified by the first argument to f1.
-            #include <stdarg.h>
-            #define MAXARGS   31
-            void f1(int n_ptrs, ...)
-            {
-                  va_list ap;
-                  char *array[MAXARGS];
-                  int ptr_no = 0;
-
-
-
-
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-
-                      if (n_ptrs > MAXARGS)
-                            n_ptrs = MAXARGS;
-                      va_start(ap, n_ptrs);
-                      while (ptr_no < n_ptrs)
-                            array[ptr_no++] = va_arg(ap, char *);
-                      va_end(ap);
-                      f2(n_ptrs, array);
-             }
-    Each call to f1 is required to have visible the definition of the function or a declaration such as
-             void f1(int, ...);
-
-7   EXAMPLE 2 The function f3 is similar, but saves the status of the variable argument list after the
-    indicated number of arguments; after f2 has been called once with the whole list, the trailing part of the list
-    is gathered again and passed to function f4.
-             #include <stdarg.h>
-             #define MAXARGS 31
-             void f3(int n_ptrs, int f4_after, ...)
-             {
-                   va_list ap, ap_save;
-                   char *array[MAXARGS];
-                   int ptr_no = 0;
-                   if (n_ptrs > MAXARGS)
-                         n_ptrs = MAXARGS;
-                   va_start(ap, f4_after);
-                   while (ptr_no < n_ptrs) {
-                         array[ptr_no++] = va_arg(ap, char *);
-                         if (ptr_no == f4_after)
-                               va_copy(ap_save, ap);
-                   }
-                   va_end(ap);
-                   f2(n_ptrs, array);
-                      // Now process the saved copy.
-                      n_ptrs -= f4_after;
-                      ptr_no = 0;
-                      while (ptr_no < n_ptrs)
-                            array[ptr_no++] = va_arg(ap_save, char *);
-                      va_end(ap_save);
-                      f4(n_ptrs, array);
-             }
-
-
-
-
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-
-    7.17 Atomics <stdatomic.h>
-    7.17.1 Introduction
-1   The header <stdatomic.h> defines several macros and declares several types and
-    functions for performing atomic operations on data shared between threads.
-2   Implementations that define the macro __STDC_NO_THREADS__ need not provide
-    this header nor support any of its facilities.
-3   The macros defined are the atomic lock-free macros
-            ATOMIC_CHAR_LOCK_FREE
-            ATOMIC_CHAR16_T_LOCK_FREE
-            ATOMIC_CHAR32_T_LOCK_FREE
-            ATOMIC_WCHAR_T_LOCK_FREE
-            ATOMIC_SHORT_LOCK_FREE
-            ATOMIC_INT_LOCK_FREE
-            ATOMIC_LONG_LOCK_FREE
-            ATOMIC_LLONG_LOCK_FREE
-            ATOMIC_ADDRESS_LOCK_FREE
-    which indicate the lock-free property of the corresponding atomic types (both signed and
-    unsigned); and
-            ATOMIC_FLAG_INIT
-    which expands to an initializer for an object of type atomic_flag.
-4   The types include
-              memory_order
-    which is an enumerated type whose enumerators identify memory ordering constraints;
-              atomic_flag
-    which is a structure type representing a lock-free, primitive atomic flag;
-              atomic_bool
-    which is a structure type representing the atomic analog of the type _Bool;
-              atomic_address
-    which is a structure type representing the atomic analog of a pointer type; and several
-    atomic analogs of integer types.
-5   In the following operation definitions:
-    -- An A refers to one of the atomic types.
-
-
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-
-        -- A C refers to its corresponding non-atomic type. The atomic_address atomic
-          type corresponds to the void * non-atomic type.
-        -- An M refers to the type of the other argument for arithmetic operations. For atomic
-          integer types, M is C. For atomic address types, M is ptrdiff_t.
-        -- The functions not ending in _explicit have the same semantics as the
-          corresponding _explicit function with memory_order_seq_cst for the
-          memory_order argument.
-    6         NOTE Many operations are volatile-qualified. The ''volatile as device register'' semantics have not
-              changed in the standard. This qualification means that volatility is preserved when applying these
-              operations to volatile objects.
-
-        7.17.2 Initialization
-        7.17.2.1 The ATOMIC_VAR_INIT macro
-        Synopsis
-1                 #include <stdatomic.h>
-                  #define ATOMIC_VAR_INIT(C value)
-        Description
-2       The ATOMIC_VAR_INIT macro expands to a token sequence suitable for initializing an
-        atomic object of a type that is initialization-compatible with value. An atomic object
-        with automatic storage duration that is not explicitly initialized using
-        ATOMIC_VAR_INIT is initially in an indeterminate state; however, the default (zero)
-        initialization for objects with static or thread-local storage duration is guaranteed to
-        produce a valid state.
-3       Concurrent access to the variable being initialized, even via an atomic operation,
-        constitutes a data race.
-4       EXAMPLE
-                  atomic_int guide = ATOMIC_VAR_INIT(42);
-
-        7.17.2.2 The atomic_init generic function
-        Synopsis
-1                 #include <stdatomic.h>
-                  void atomic_init(volatile A *obj, C value);
-        Description
-2       The atomic_init generic function initializes the atomic object pointed to by obj to
-        the value value, while also initializing any additional state that the implementation
-        might need to carry for the atomic object.
-
-
-
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-
-3   Although this function initializes an atomic object, it does not avoid data races;
-    concurrent access to the variable being initialized, even via an atomic operation,
-    constitutes a data race.
-    Returns
-4   The atomic_init generic function returns no value.
-5   EXAMPLE
-              atomic_int guide;
-              atomic_init(&guide, 42);
-
-    7.17.3 Order and consistency
-1   The enumerated type memory_order specifies the detailed regular (non-atomic)
-    memory synchronization operations as defined in 5.1.2.4 and may provide for operation
-    ordering. Its enumeration constants are as follows:
-              memory_order_relaxed
-              memory_order_consume
-              memory_order_acquire
-              memory_order_release
-              memory_order_acq_rel
-              memory_order_seq_cst
-2   For memory_order_relaxed, no operation orders memory.
-3   For       memory_order_release,       memory_order_acq_rel,             and
-    memory_order_seq_cst, a store operation performs a release operation on the
-    affected memory location.
-4   For       memory_order_acquire,       memory_order_acq_rel,             and
-    memory_order_seq_cst, a load operation performs an acquire operation on the
-    affected memory location.
-5   For memory_order_consume, a load operation performs a consume operation on the
-    affected memory location.
-6   For memory_order_seq_cst, there shall be a single total order S on all operations,
-    consistent with the ''happens before'' order and modification orders for all affected
-    locations, such that each memory_order_seq_cst operation that loads a value
-    observes either the last preceding modification according to this order S, or the result of
-    an operation that is not memory_order_seq_cst.
-7   NOTE 1 Although it is not explicitly required that S include lock operations, it can always be extended to
-    an order that does include lock and unlock operations, since the ordering between those is already included
-    in the ''happens before'' ordering.
-
-8   NOTE 2 Atomic operations specifying memory_order_relaxed are relaxed only with respect to
-    memory ordering. Implementations must still guarantee that any given atomic access to a particular atomic
-
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-
-     object be indivisible with respect to all other atomic accesses to that object.
-
-9    For an atomic operation B that reads the value of an atomic object M, if there is a
-     memory_order_seq_cst fence X sequenced before B, then B observes either the
-     last memory_order_seq_cst modification of M preceding X in the total order S or
-     a later modification of M in its modification order.
-10   For atomic operations A and B on an atomic object M, where A modifies M and B takes
-     its value, if there is a memory_order_seq_cst fence X such that A is sequenced
-     before X and B follows X in S, then B observes either the effects of A or a later
-     modification of M in its modification order.
-11   For atomic operations A and B on an atomic object M, where A modifies M and B takes
-     its value, if there are memory_order_seq_cst fences X and Y such that A is
-     sequenced before X, Y is sequenced before B, and X precedes Y in S, then B observes
-     either the effects of A or a later modification of M in its modification order.
-12   Atomic read-modify-write operations shall always read the last value (in the modification
-     order) stored before the write associated with the read-modify-write operation.
-13   An atomic store shall only store a value that has been computed from constants and
-     program input values by a finite sequence of program evaluations, such that each
-     evaluation observes the values of variables as computed by the last prior assignment in
-     the sequence.247) The ordering of evaluations in this sequence shall be such that
-     -- If an evaluation B observes a value computed by A in a different thread, then B does
-       not happen before A.
-     -- If an evaluation A is included in the sequence, then all evaluations that assign to the
-       same variable and happen before A are also included.
-14   NOTE 3 The second requirement disallows ''out-of-thin-air'', or ''speculative'' stores of atomics when
-     relaxed atomics are used. Since unordered operations are involved, evaluations may appear in this
-     sequence out of thread order. For example, with x and y initially zero,
-              // Thread 1:
-              r1 = atomic_load_explicit(&y, memory_order_relaxed);
-              atomic_store_explicit(&x, r1, memory_order_relaxed);
-
-              // Thread 2:
-              r2 = atomic_load_explicit(&x, memory_order_relaxed);
-              atomic_store_explicit(&y, 42, memory_order_relaxed);
-     is allowed to produce r1 == 42 && r2 == 42. The sequence of evaluations justifying this consists of:
-
-
-
-
-     247) Among other implications, atomic variables shall not decay.
-
-[page 274] (Contents)
-
-             atomic_store_explicit(&y, 42,               memory_order_relaxed);
-             r1 = atomic_load_explicit(&y,               memory_order_relaxed);
-             atomic_store_explicit(&x, r1,               memory_order_relaxed);
-             r2 = atomic_load_explicit(&x,               memory_order_relaxed);
-     On the other hand,
-             // Thread 1:
-             r1 = atomic_load_explicit(&y, memory_order_relaxed);
-             atomic_store_explicit(&x, r1, memory_order_relaxed);
-
-             // Thread 2:
-             r2 = atomic_load_explicit(&x, memory_order_relaxed);
-             atomic_store_explicit(&y, r2, memory_order_relaxed);
-     is not allowed to produce r1 == 42 && r2 = 42, since there is no sequence of evaluations that results
-     in the computation of 42. In the absence of ''relaxed'' operations and read-modify-write operations with
-     weaker than memory_order_acq_rel ordering, the second requirement has no impact.
-
-     Recommended practice
-15   The requirements do not forbid r1 == 42 && r2 == 42 in the following example,
-     with x and y initially zero:
-             // Thread 1:
-             r1 = atomic_load_explicit(&x, memory_order_relaxed);
-             if (r1 == 42)
-                  atomic_store_explicit(&y, r1, memory_order_relaxed);
-
-             // Thread 2:
-             r2 = atomic_load_explicit(&y, memory_order_relaxed);
-             if (r2 == 42)
-                  atomic_store_explicit(&x, 42, memory_order_relaxed);
-     However, this is not useful behavior, and implementations should not allow it.
-16   Implementations should make atomic stores visible to atomic loads within a reasonable
-     amount of time.
-     7.17.3.1 The kill_dependency macro
-     Synopsis
-1            #include <stdatomic.h>
-             type kill_dependency(type y);
-     Description
-2    The kill_dependency macro terminates a dependency chain; the argument does not
-     carry a dependency to the return value.
-
-
-
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-
-    Returns
-3   The kill_dependency macro returns the value of y.
-    7.17.4 Fences
-1   This subclause introduces synchronization primitives called fences. Fences can have
-    acquire semantics, release semantics, or both. A fence with acquire semantics is called
-    an acquire fence; a fence with release semantics is called a release fence.
-2   A release fence A synchronizes with an acquire fence B if there exist atomic operations
-    X and Y , both operating on some atomic object M, such that A is sequenced before X, X
-    modifies M, Y is sequenced before B, and Y reads the value written by X or a value
-    written by any side effect in the hypothetical release sequence X would head if it were a
-    release operation.
-3   A release fence A synchronizes with an atomic operation B that performs an acquire
-    operation on an atomic object M if there exists an atomic operation X such that A is
-    sequenced before X, X modifies M, and B reads the value written by X or a value written
-    by any side effect in the hypothetical release sequence X would head if it were a release
-    operation.
-4   An atomic operation A that is a release operation on an atomic object M synchronizes
-    with an acquire fence B if there exists some atomic operation X on M such that X is
-    sequenced before B and reads the value written by A or a value written by any side effect
-    in the release sequence headed by A.
-    7.17.4.1 The atomic_thread_fence function
-    Synopsis
-1          #include <stdatomic.h>
-           void atomic_thread_fence(memory_order order);
-    Description
-2   Depending on the value of order, this operation:
-    -- has no effects, if order == memory_order_relaxed;
-    -- is an acquire fence, if order == memory_order_acquire or order ==
-      memory_order_consume;
-    -- is a release fence, if order == memory_order_release;
-    -- is both an acquire fence              and   a    release   fence,   if   order      ==
-      memory_order_acq_rel;
-    -- is a sequentially consistent acquire and release fence, if order                    ==
-      memory_order_seq_cst.
-
-
-[page 276] (Contents)
-
-    Returns
-3   The atomic_thread_fence function returns no value.
-    7.17.4.2 The atomic_signal_fence function
-    Synopsis
-1           #include <stdatomic.h>
-            void atomic_signal_fence(memory_order order);
-    Description
-2   Equivalent to atomic_thread_fence(order), except that ''synchronizes with''
-    relationships are established only between a thread and a signal handler executed in the
-    same thread.
-3   NOTE 1 The atomic_signal_fence function can be used to specify the order in which actions
-    performed by the thread become visible to the signal handler.
-
-4   NOTE 2 Compiler optimizations and reorderings of loads and stores are inhibited in the same way as with
-    atomic_thread_fence, but the hardware fence instructions that atomic_thread_fence would
-    have inserted are not emitted.
-
-    Returns
-5   The atomic_signal_fence function returns no value.
-    7.17.5 Lock-free property
-1   The atomic lock-free macros indicate the lock-free property of integer and address atomic
-    types. A value of 0 indicates that the type is never lock-free; a value of 1 indicates that
-    the type is sometimes lock-free; a value of 2 indicates that the type is always lock-free.
-2   NOTE Operations that are lock-free should also be address-free. That is, atomic operations on the same
-    memory location via two different addresses will communicate atomically. The implementation should not
-    depend on any per-process state. This restriction enables communication via memory mapped into a
-    process more than once and memory shared between two processes.
-
-    7.17.5.1 The atomic_is_lock_free generic function
-    Synopsis
-1           #include <stdatomic.h>
-            _Bool atomic_is_lock_free(atomic_type const volatile *obj);
-    Description
-2   The atomic_is_lock_free generic function indicates whether or not the object
-    pointed to by obj is lock-free. atomic_type can be any atomic type.
-    Returns
-3   The atomic_is_lock_free generic function returns nonzero (true) if and only if the
-    object's operations are lock-free. The result of a lock-free query on one object cannot be
-
-[page 277] (Contents)
-
-    inferred from the result of a lock-free query on another object.
-    7.17.6 Atomic integer and address types
-1   For each line in the following table, the atomic type name is declared as the
-    corresponding direct type.
-
-
-
-
-[page 278] (Contents)
-
-
-
-                Atomic type name                             Direct type
-            atomic_char                          _Atomic    char
-            atomic_schar                         _Atomic    signed char
-            atomic_uchar                         _Atomic    unsigned char
-            atomic_short                         _Atomic    short
-            atomic_ushort                        _Atomic    unsigned short
-            atomic_int                           _Atomic    int
-            atomic_uint                          _Atomic    unsigned int
-            atomic_long                          _Atomic    long
-            atomic_ulong                         _Atomic    unsigned long
-            atomic_llong                         _Atomic    long long
-            atomic_ullong                        _Atomic    unsigned long long
-            atomic_char16_t                      _Atomic    char16_t
-            atomic_char32_t                      _Atomic    char32_t
-            atomic_wchar_t                       _Atomic    wchar_t
-            atomic_int_least8_t                  _Atomic    int_least8_t
-            atomic_uint_least8_t                 _Atomic    uint_least8_t
-            atomic_int_least16_t                 _Atomic    int_least16_t
-            atomic_uint_least16_t                _Atomic    uint_least16_t
-            atomic_int_least32_t                 _Atomic    int_least32_t
-            atomic_uint_least32_t                _Atomic    uint_least32_t
-            atomic_int_least64_t                 _Atomic    int_least64_t
-            atomic_uint_least64_t                _Atomic    uint_least64_t
-            atomic_int_fast8_t                   _Atomic    int_fast8_t
-            atomic_uint_fast8_t                  _Atomic    uint_fast8_t
-            atomic_int_fast16_t                  _Atomic    int_fast16_t
-            atomic_uint_fast16_t                 _Atomic    uint_fast16_t
-            atomic_int_fast32_t                  _Atomic    int_fast32_t
-            atomic_uint_fast32_t                 _Atomic    uint_fast32_t
-            atomic_int_fast64_t                  _Atomic    int_fast64_t
-            atomic_uint_fast64_t                 _Atomic    uint_fast64_t
-            atomic_intptr_t                      _Atomic    intptr_t
-            atomic_uintptr_t                     _Atomic    uintptr_t
-            atomic_size_t                        _Atomic    size_t
-            atomic_ptrdiff_t                     _Atomic    ptrdiff_t
-            atomic_intmax_t                      _Atomic    intmax_t
-            atomic_uintmax_t                     _Atomic    uintmax_t
-2   The semantics of the operations on these types are defined in 7.17.7.
-
-
-
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-
-3   The atomic_bool type provides an atomic boolean.
-4   The atomic_address type provides atomic void * operations. The unit of
-    addition/subtraction shall be one byte.
-5   NOTE The representation of atomic integer and address types need not have the same size as their
-    corresponding regular types. They should have the same size whenever possible, as it eases effort required
-    to port existing code.
-
-    7.17.7 Operations on atomic types
-1   There are only a few kinds of operations on atomic types, though there are many
-    instances of those kinds. This subclause specifies each general kind.
-    7.17.7.1 The atomic_store generic functions
-    Synopsis
-1           #include <stdatomic.h>
-            void atomic_store(volatile A *object, C desired);
-            void atomic_store_explicit(volatile A *object,
-                 C desired, memory_order order);
-    Description
-2   The      order      argument    shall    not    be    memory_order_acquire,
-    memory_order_consume, nor memory_order_acq_rel. Atomically replace the
-    value pointed to by object with the value of desired. Memory is affected according
-    to the value of order.
-    Returns
-3   The atomic_store generic functions return no value.
-    7.17.7.2 The atomic_load generic functions
-    Synopsis
-1           #include <stdatomic.h>
-            C atomic_load(volatile A *object);
-            C atomic_load_explicit(volatile A *object,
-                 memory_order order);
-    Description
-2   The order argument shall not be memory_order_release nor
-    memory_order_acq_rel. Memory is affected according to the value of order.
-    Returns
-    Atomically returns the value pointed to by object.
-
-
-
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-
-    7.17.7.3 The atomic_exchange generic functions
-    Synopsis
-1            #include <stdatomic.h>
-             C atomic_exchange(volatile A *object, C desired);
-             C atomic_exchange_explicit(volatile A *object,
-                  C desired, memory_order order);
-    Description
-2   Atomically replace the value pointed to by object with desired. Memory is affected
-    according to the value of order. These operations are read-modify-write operations
-    (5.1.2.4).
-    Returns
-3   Atomically returns the value pointed to by object immediately before the effects.
-    7.17.7.4 The atomic_compare_exchange generic functions
-    Synopsis
-1            #include <stdatomic.h>
-             _Bool atomic_compare_exchange_strong(volatile A *object,
-                  C *expected, C desired);
-             _Bool atomic_compare_exchange_strong_explicit(
-                  volatile A *object, C *expected, C desired,
-                  memory_order success, memory_order failure);
-             _Bool atomic_compare_exchange_weak(volatile A *object,
-                  C *expected, C desired);
-             _Bool atomic_compare_exchange_weak_explicit(
-                  volatile A *object, C *expected, C desired,
-                  memory_order success, memory_order failure);
-    Description
-2   The failure argument shall not be memory_order_release nor
-    memory_order_acq_rel. The failure argument shall be no stronger than the
-    success argument. Atomically, compares the value pointed to by object for equality
-    with that in expected, and if true, replaces the value pointed to by object with
-    desired, and if false, updates the value in expected with the value pointed to by
-    object. Further, if the comparison is true, memory is affected according to the value of
-    success, and if the comparison is false, memory is affected according to the value of
-    failure. These operations are atomic read-modify-write operations (5.1.2.4).
-3   NOTE 1    The effect of the compare-and-exchange operations is
-
-
-
-
-[page 281] (Contents)
-
-             if (*object == *expected)
-                   *object = desired;
-             else
-                   *expected = *object;
-
-4   The weak compare-and-exchange operations may fail spuriously, that is, return zero
-    while leaving the value pointed to by expected unchanged.
-5   NOTE 2 This spurious failure enables implementation of compare-and-exchange on a broader class of
-    machines, e.g. load-locked store-conditional machines.
-
-6   EXAMPLE         A consequence of spurious failure is that nearly all uses of weak compare-and-exchange will
-    be in a loop.
-             exp = atomic_load(&cur);
-             do {
-                   des = function(exp);
-             } while (!atomic_compare_exchange_weak(&cur, &exp, des));
-    When a compare-and-exchange is in a loop, the weak version will yield better performance on some
-    platforms. When a weak compare-and-exchange would require a loop and a strong one would not, the
-    strong one is preferable.
-
-    Returns
-7   The result of the comparison.
-    7.17.7.5 The atomic_fetch and modify generic functions
-1   The following operations perform arithmetic and bitwise computations. All of these
-    operations are applicable to an object of any atomic integer type. Only addition and
-    subtraction are applicable to atomic_address. None of these operations is applicable
-    to atomic_bool. The key, operator, and computation correspondence is:
-
-
-     key            op          computation
-     add            +       addition
-     sub            -       subtraction
-     or             |       bitwise inclusive or
-     xor            ^       bitwise exclusive or
-     and            &       bitwise and
-    Synopsis
-2            #include <stdatomic.h>
-             C atomic_fetch_key(volatile A *object, M operand);
-             C atomic_fetch_key_explicit(volatile A *object,
-                  M operand, memory_order order);
-    Description
-3   Atomically replaces the value pointed to by object with the result of the computation
-    applied to the value pointed to by object and the given operand. Memory is affected
-[page 282] (Contents)
-
-    according to the value of order. These operations are atomic read-modify-write
-    operations (5.1.2.4). For signed integer types, arithmetic is defined to use two's-
-    complement representation. There are no undefined results. For address types, the result
-    may be an undefined address, but the operations otherwise have no undefined behavior.
-    Returns
-4   Atomically, the value pointed to by object immediately before the effects.
-5   NOTE The operation of the atomic_fetch and modify generic functions are nearly equivalent to the
-    operation of the corresponding op= compound assignment operators. The only differences are that the
-    compound assignment operators are not guaranteed to operate atomically, and the value yielded by a
-    compound assignment operator is the updated value of the object, whereas the value returned by the
-    atomic_fetch and modify generic functions is the previous value of the atomic object.
-
-    7.17.8 Atomic flag type and operations
-1   The atomic_flag type provides the classic test-and-set functionality. It has two
-    states, set and clear.
-2   Operations on an object of type atomic_flag shall be lock free.
-3   NOTE Hence the operations should also be address-free. No other type requires lock-free operations, so
-    the atomic_flag type is the minimum hardware-implemented type needed to conform to this
-    International standard. The remaining types can be emulated with atomic_flag, though with less than
-    ideal properties.
-
-4   The macro ATOMIC_FLAG_INIT may be used to initialize an atomic_flag to the
-    clear state. An atomic_flag that is not explicitly initialized with
-    ATOMIC_FLAG_INIT is initially in an indeterminate state.
-5   EXAMPLE
-            atomic_flag guard = ATOMIC_FLAG_INIT;
-
-    7.17.8.1 The atomic_flag_test_and_set functions
-    Synopsis
-1           #include <stdatomic.h>
-            bool atomic_flag_test_and_set(
-                 volatile atomic_flag *object);
-            bool atomic_flag_test_and_set_explicit(
-                 volatile atomic_flag *object, memory_order order);
-    Description
-2   Atomically sets the value pointed to by object to true. Memory is affected according
-    to the value of order. These operations are atomic read-modify-write operations
-    (5.1.2.4).
-
-
-
-
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-
-    Returns
-3   Atomically, the value of the object immediately before the effects.
-    7.17.8.2 The atomic_flag_clear functions
-    Synopsis
-1          #include <stdatomic.h>
-           void atomic_flag_clear(volatile atomic_flag *object);
-           void atomic_flag_clear_explicit(
-                volatile atomic_flag *object, memory_order order);
-    Description
-2   The order argument shall not be memory_order_acquire nor
-    memory_order_acq_rel. Atomically sets the value pointed to by object to false.
-    Memory is affected according to the value of order.
-    Returns
-3   The atomic_flag_clear functions return no value.
-
-
-
-
-[page 284] (Contents)
-
-    7.18 Boolean type and values <stdbool.h>
-1   The header <stdbool.h> defines four macros.
-2   The macro
-             bool
-    expands to _Bool.
-3   The remaining three macros are suitable for use in #if preprocessing directives. They
-    are
-             true
-    which expands to the integer constant 1,
-             false
-    which expands to the integer constant 0, and
-             __bool_true_false_are_defined
-    which expands to the integer constant 1.
-4   Notwithstanding the provisions of 7.1.3, a program may undefine and perhaps then
-    redefine the macros bool, true, and false.248)
-
-
-
-
-    248) See ''future library directions'' (7.30.7).
-
-[page 285] (Contents)
-
-    7.19 Common definitions <stddef.h>
-1   The header <stddef.h> defines the following macros and declares the following types.
-    Some are also defined in other headers, as noted in their respective subclauses.
-2   The types are
-           ptrdiff_t
-    which is the signed integer type of the result of subtracting two pointers;
-           size_t
-    which is the unsigned integer type of the result of the sizeof operator;
-           max_align_t
-    which is an object type whose alignment is as great as is supported by the implementation
-    in all contexts; and
-           wchar_t
-    which is an integer type whose range of values can represent distinct codes for all
-    members of the largest extended character set specified among the supported locales; the
-    null character shall have the code value zero. Each member of the basic character set
-    shall have a code value equal to its value when used as the lone character in an integer
-    character      constant     if     an      implementation      does      not      define
-    __STDC_MB_MIGHT_NEQ_WC__.
-3   The macros are
-           NULL
-    which expands to an implementation-defined null pointer constant; and
-           offsetof(type, member-designator)
-    which expands to an integer constant expression that has type size_t, the value of
-    which is the offset in bytes, to the structure member (designated by member-designator),
-    from the beginning of its structure (designated by type). The type and member designator
-    shall be such that given
-           static type t;
-    then the expression &(t.member-designator) evaluates to an address constant. (If the
-    specified member is a bit-field, the behavior is undefined.)
-    Recommended practice
-4   The types used for size_t and ptrdiff_t should not have an integer conversion rank
-    greater than that of signed long int unless the implementation supports objects
-    large enough to make this necessary.
-
-[page 286] (Contents)
-
-Forward references: localization (7.11).
-
-
-
-
-[page 287] (Contents)
-
-    7.20 Integer types <stdint.h>
-1   The header <stdint.h> declares sets of integer types having specified widths, and
-    defines corresponding sets of macros.249) It also defines macros that specify limits of
-    integer types corresponding to types defined in other standard headers.
-2   Types are defined in the following categories:
-    -- integer types having certain exact widths;
-    -- integer types having at least certain specified widths;
-    -- fastest integer types having at least certain specified widths;
-    -- integer types wide enough to hold pointers to objects;
-    -- integer types having greatest width.
-    (Some of these types may denote the same type.)
-3   Corresponding macros specify limits of the declared types and construct suitable
-    constants.
-4   For each type described herein that the implementation provides,250) <stdint.h> shall
-    declare that typedef name and define the associated macros. Conversely, for each type
-    described herein that the implementation does not provide, <stdint.h> shall not
-    declare that typedef name nor shall it define the associated macros. An implementation
-    shall provide those types described as ''required'', but need not provide any of the others
-    (described as ''optional'').
-    7.20.1 Integer types
-1   When typedef names differing only in the absence or presence of the initial u are defined,
-    they shall denote corresponding signed and unsigned types as described in 6.2.5; an
-    implementation providing one of these corresponding types shall also provide the other.
-2   In the following descriptions, the symbol N represents an unsigned decimal integer with
-    no leading zeros (e.g., 8 or 24, but not 04 or 048).
-
-
-
-
-    249) See ''future library directions'' (7.30.8).
-    250) Some of these types may denote implementation-defined extended integer types.
-
-[page 288] (Contents)
-
-    7.20.1.1 Exact-width integer types
-1   The typedef name intN_t designates a signed integer type with width N , no padding
-    bits, and a two's complement representation. Thus, int8_t denotes such a signed
-    integer type with a width of exactly 8 bits.
-2   The typedef name uintN_t designates an unsigned integer type with width N and no
-    padding bits. Thus, uint24_t denotes such an unsigned integer type with a width of
-    exactly 24 bits.
-3   These types are optional. However, if an implementation provides integer types with
-    widths of 8, 16, 32, or 64 bits, no padding bits, and (for the signed types) that have a
-    two's complement representation, it shall define the corresponding typedef names.
-    7.20.1.2 Minimum-width integer types
-1   The typedef name int_leastN_t designates a signed integer type with a width of at
-    least N , such that no signed integer type with lesser size has at least the specified width.
-    Thus, int_least32_t denotes a signed integer type with a width of at least 32 bits.
-2   The typedef name uint_leastN_t designates an unsigned integer type with a width
-    of at least N , such that no unsigned integer type with lesser size has at least the specified
-    width. Thus, uint_least16_t denotes an unsigned integer type with a width of at
-    least 16 bits.
-3   The following types are required:
-             int_least8_t                                      uint_least8_t
-             int_least16_t                                     uint_least16_t
-             int_least32_t                                     uint_least32_t
-             int_least64_t                                     uint_least64_t
-    All other types of this form are optional.
-    7.20.1.3 Fastest minimum-width integer types
-1   Each of the following types designates an integer type that is usually fastest251) to operate
-    with among all integer types that have at least the specified width.
-2   The typedef name int_fastN_t designates the fastest signed integer type with a width
-    of at least N . The typedef name uint_fastN_t designates the fastest unsigned integer
-    type with a width of at least N .
-
-
-
-
-    251) The designated type is not guaranteed to be fastest for all purposes; if the implementation has no clear
-         grounds for choosing one type over another, it will simply pick some integer type satisfying the
-         signedness and width requirements.
-
-[page 289] (Contents)
-
-3   The following types are required:
-           int_fast8_t                                     uint_fast8_t
-           int_fast16_t                                    uint_fast16_t
-           int_fast32_t                                    uint_fast32_t
-           int_fast64_t                                    uint_fast64_t
-    All other types of this form are optional.
-    7.20.1.4 Integer types capable of holding object pointers
-1   The following type designates a signed integer type with the property that any valid
-    pointer to void can be converted to this type, then converted back to pointer to void,
-    and the result will compare equal to the original pointer:
-           intptr_t
-    The following type designates an unsigned integer type with the property that any valid
-    pointer to void can be converted to this type, then converted back to pointer to void,
-    and the result will compare equal to the original pointer:
-           uintptr_t
-    These types are optional.
-    7.20.1.5 Greatest-width integer types
-1   The following type designates a signed integer type capable of representing any value of
-    any signed integer type:
-           intmax_t
-    The following type designates an unsigned integer type capable of representing any value
-    of any unsigned integer type:
-           uintmax_t
-    These types are required.
-    7.20.2 Limits of specified-width integer types
-1   The following object-like macros specify the minimum and maximum limits of the types
-    declared in <stdint.h>. Each macro name corresponds to a similar type name in
-    7.20.1.
-2   Each instance of any defined macro shall be replaced by a constant expression suitable
-    for use in #if preprocessing directives, and this expression shall have the same type as
-    would an expression that is an object of the corresponding type converted according to
-    the integer promotions. Its implementation-defined value shall be equal to or greater in
-    magnitude (absolute value) than the corresponding value given below, with the same sign,
-    except where stated to be exactly the given value.
-
-[page 290] (Contents)
-
-    7.20.2.1 Limits of exact-width integer types
-1   -- minimum values of exact-width signed integer types
-       INTN_MIN                                     exactly -(2 N -1 )
-    -- maximum values of exact-width signed integer types
-       INTN_MAX                                     exactly 2 N -1 - 1
-    -- maximum values of exact-width unsigned integer types
-       UINTN_MAX                                    exactly 2 N - 1
-    7.20.2.2 Limits of minimum-width integer types
-1   -- minimum values of minimum-width signed integer types
-       INT_LEASTN_MIN                                       -(2 N -1 - 1)
-    -- maximum values of minimum-width signed integer types
-       INT_LEASTN_MAX                                       2 N -1 - 1
-    -- maximum values of minimum-width unsigned integer types
-       UINT_LEASTN_MAX                                      2N - 1
-    7.20.2.3 Limits of fastest minimum-width integer types
-1   -- minimum values of fastest minimum-width signed integer types
-       INT_FASTN_MIN                                        -(2 N -1 - 1)
-    -- maximum values of fastest minimum-width signed integer types
-       INT_FASTN_MAX                                        2 N -1 - 1
-    -- maximum values of fastest minimum-width unsigned integer types
-       UINT_FASTN_MAX                                       2N - 1
-    7.20.2.4 Limits of integer types capable of holding object pointers
-1   -- minimum value of pointer-holding signed integer type
-       INTPTR_MIN                                           -(215 - 1)
-    -- maximum value of pointer-holding signed integer type
-       INTPTR_MAX                                           215 - 1
-    -- maximum value of pointer-holding unsigned integer type
-       UINTPTR_MAX                                          216 - 1
-
-
-
-[page 291] (Contents)
-
-    7.20.2.5 Limits of greatest-width integer types
-1   -- minimum value of greatest-width signed integer type
-          INTMAX_MIN                                                  -(263 - 1)
-    -- maximum value of greatest-width signed integer type
-        INTMAX_MAX                                                    263 - 1
-    -- maximum value of greatest-width unsigned integer type
-        UINTMAX_MAX                                                   264 - 1
-    7.20.3 Limits of other integer types
-1   The following object-like macros specify the minimum and maximum limits of integer
-    types corresponding to types defined in other standard headers.
-2   Each instance of these macros shall be replaced by a constant expression suitable for use
-    in #if preprocessing directives, and this expression shall have the same type as would an
-    expression that is an object of the corresponding type converted according to the integer
-    promotions. Its implementation-defined value shall be equal to or greater in magnitude
-    (absolute value) than the corresponding value given below, with the same sign. An
-    implementation shall define only the macros corresponding to those typedef names it
-    actually provides.252)
-    -- limits of ptrdiff_t
-        PTRDIFF_MIN                                                 -65535
-        PTRDIFF_MAX                                                 +65535
-    -- limits of sig_atomic_t
-        SIG_ATOMIC_MIN                                              see below
-        SIG_ATOMIC_MAX                                              see below
-    -- limit of size_t
-        SIZE_MAX                                                      65535
-    -- limits of wchar_t
-        WCHAR_MIN                                                   see below
-        WCHAR_MAX                                                   see below
-    -- limits of wint_t
-
-
-
-
-    252) A freestanding implementation need not provide all of these types.
-
-[page 292] (Contents)
-
-        WINT_MIN                                              see below
-        WINT_MAX                                              see below
-3   If sig_atomic_t (see 7.14) is defined as a signed integer type, the value of
-    SIG_ATOMIC_MIN shall be no greater than -127 and the value of SIG_ATOMIC_MAX
-    shall be no less than 127; otherwise, sig_atomic_t is defined as an unsigned integer
-    type, and the value of SIG_ATOMIC_MIN shall be 0 and the value of
-    SIG_ATOMIC_MAX shall be no less than 255.
-4   If wchar_t (see 7.19) is defined as a signed integer type, the value of WCHAR_MIN
-    shall be no greater than -127 and the value of WCHAR_MAX shall be no less than 127;
-    otherwise, wchar_t is defined as an unsigned integer type, and the value of
-    WCHAR_MIN shall be 0 and the value of WCHAR_MAX shall be no less than 255.253)
-5   If wint_t (see 7.28) is defined as a signed integer type, the value of WINT_MIN shall
-    be no greater than -32767 and the value of WINT_MAX shall be no less than 32767;
-    otherwise, wint_t is defined as an unsigned integer type, and the value of WINT_MIN
-    shall be 0 and the value of WINT_MAX shall be no less than 65535.
-    7.20.4 Macros for integer constants
-1   The following function-like macros expand to integer constants suitable for initializing
-    objects that have integer types corresponding to types defined in <stdint.h>. Each
-    macro name corresponds to a similar type name in 7.20.1.2 or 7.20.1.5.
-2   The argument in any instance of these macros shall be an unsuffixed integer constant (as
-    defined in 6.4.4.1) with a value that does not exceed the limits for the corresponding type.
-3   Each invocation of one of these macros shall expand to an integer constant expression
-    suitable for use in #if preprocessing directives. The type of the expression shall have
-    the same type as would an expression of the corresponding type converted according to
-    the integer promotions. The value of the expression shall be that of the argument.
-    7.20.4.1 Macros for minimum-width integer constants
-1   The macro INTN_C(value) shall expand to an integer constant expression
-    corresponding to the type int_leastN_t. The macro UINTN_C(value) shall expand
-    to an integer constant expression corresponding to the type uint_leastN_t. For
-    example, if uint_least64_t is a name for the type unsigned long long int,
-    then UINT64_C(0x123) might expand to the integer constant 0x123ULL.
-
-
-
-
-    253) The values WCHAR_MIN and WCHAR_MAX do not necessarily correspond to members of the extended
-         character set.
-
-[page 293] (Contents)
-
-    7.20.4.2 Macros for greatest-width integer constants
-1   The following macro expands to an integer constant expression having the value specified
-    by its argument and the type intmax_t:
-           INTMAX_C(value)
-    The following macro expands to an integer constant expression having the value specified
-    by its argument and the type uintmax_t:
-           UINTMAX_C(value)
-
-
-
-
-[page 294] (Contents)
-
-    7.21 Input/output <stdio.h>
-    7.21.1 Introduction
-1   The header <stdio.h> defines several macros, and declares three types and many
-    functions for performing input and output.
-2   The types declared are size_t (described in 7.19);
-            FILE
-    which is an object type capable of recording all the information needed to control a
-    stream, including its file position indicator, a pointer to its associated buffer (if any), an
-    error indicator that records whether a read/write error has occurred, and an end-of-file
-    indicator that records whether the end of the file has been reached; and
-            fpos_t
-    which is a complete object type other than an array type capable of recording all the
-    information needed to specify uniquely every position within a file.
-3   The macros are NULL (described in 7.19);
-            _IOFBF
-            _IOLBF
-            _IONBF
-    which expand to integer constant expressions with distinct values, suitable for use as the
-    third argument to the setvbuf function;
-            BUFSIZ
-    which expands to an integer constant expression that is the size of the buffer used by the
-    setbuf function;
-            EOF
-    which expands to an integer constant expression, with type int and a negative value, that
-    is returned by several functions to indicate end-of-file, that is, no more input from a
-    stream;
-              FOPEN_MAX
-    which expands to an integer constant expression that is the minimum number of files that
-    the implementation guarantees can be open simultaneously;
-              FILENAME_MAX
-    which expands to an integer constant expression that is the size needed for an array of
-    char large enough to hold the longest file name string that the implementation
-
-
-
-[page 295] (Contents)
-
-    guarantees can be opened;254)
-            L_tmpnam
-    which expands to an integer constant expression that is the size needed for an array of
-    char large enough to hold a temporary file name string generated by the tmpnam
-    function;
-            SEEK_CUR
-            SEEK_END
-            SEEK_SET
-    which expand to integer constant expressions with distinct values, suitable for use as the
-    third argument to the fseek function;
-            TMP_MAX
-    which expands to an integer constant expression that is the minimum number of unique
-    file names that can be generated by the tmpnam function;
-            stderr
-            stdin
-            stdout
-    which are expressions of type ''pointer to FILE'' that point to the FILE objects
-    associated, respectively, with the standard error, input, and output streams.
-4   The header <wchar.h> declares a number of functions useful for wide character input
-    and output. The wide character input/output functions described in that subclause
-    provide operations analogous to most of those described here, except that the
-    fundamental units internal to the program are wide characters. The external
-    representation (in the file) is a sequence of ''generalized'' multibyte characters, as
-    described further in 7.21.3.
-5   The input/output functions are given the following collective terms:
-    -- The wide character input functions -- those functions described in 7.28 that perform
-      input into wide characters and wide strings: fgetwc, fgetws, getwc, getwchar,
-      fwscanf, wscanf, vfwscanf, and vwscanf.
-    -- The wide character output functions -- those functions described in 7.28 that perform
-      output from wide characters and wide strings: fputwc, fputws, putwc,
-      putwchar, fwprintf, wprintf, vfwprintf, and vwprintf.
-
-
-    254) If the implementation imposes no practical limit on the length of file name strings, the value of
-         FILENAME_MAX should instead be the recommended size of an array intended to hold a file name
-         string. Of course, file name string contents are subject to other system-specific constraints; therefore
-         all possible strings of length FILENAME_MAX cannot be expected to be opened successfully.
-
-[page 296] (Contents)
-
-    -- The wide character input/output functions -- the union of the ungetwc function, the
-      wide character input functions, and the wide character output functions.
-    -- The byte input/output functions -- those functions described in this subclause that
-      perform input/output: fgetc, fgets, fprintf, fputc, fputs, fread,
-      fscanf, fwrite, getc, getchar, printf, putc, putchar, puts, scanf,
-      ungetc, vfprintf, vfscanf, vprintf, and vscanf.
-    Forward references: files (7.21.3), the fseek function (7.21.9.2), streams (7.21.2), the
-    tmpnam function (7.21.4.4), <wchar.h> (7.28).
-    7.21.2 Streams
-1   Input and output, whether to or from physical devices such as terminals and tape drives,
-    or whether to or from files supported on structured storage devices, are mapped into
-    logical data streams, whose properties are more uniform than their various inputs and
-    outputs. Two forms of mapping are supported, for text streams and for binary
-    streams.255)
-2   A text stream is an ordered sequence of characters composed into lines, each line
-    consisting of zero or more characters plus a terminating new-line character. Whether the
-    last line requires a terminating new-line character is implementation-defined. Characters
-    may have to be added, altered, or deleted on input and output to conform to differing
-    conventions for representing text in the host environment. Thus, there need not be a one-
-    to-one correspondence between the characters in a stream and those in the external
-    representation. Data read in from a text stream will necessarily compare equal to the data
-    that were earlier written out to that stream only if: the data consist only of printing
-    characters and the control characters horizontal tab and new-line; no new-line character is
-    immediately preceded by space characters; and the last character is a new-line character.
-    Whether space characters that are written out immediately before a new-line character
-    appear when read in is implementation-defined.
-3   A binary stream is an ordered sequence of characters that can transparently record
-    internal data. Data read in from a binary stream shall compare equal to the data that were
-    earlier written out to that stream, under the same implementation. Such a stream may,
-    however, have an implementation-defined number of null characters appended to the end
-    of the stream.
-4   Each stream has an orientation. After a stream is associated with an external file, but
-    before any operations are performed on it, the stream is without orientation. Once a wide
-    character input/output function has been applied to a stream without orientation, the
-
-
-    255) An implementation need not distinguish between text streams and binary streams. In such an
-         implementation, there need be no new-line characters in a text stream nor any limit to the length of a
-         line.
-
-[page 297] (Contents)
-
-    stream becomes a wide-oriented stream. Similarly, once a byte input/output function has
-    been applied to a stream without orientation, the stream becomes a byte-oriented stream.
-    Only a call to the freopen function or the fwide function can otherwise alter the
-    orientation of a stream. (A successful call to freopen removes any orientation.)256)
-5   Byte input/output functions shall not be applied to a wide-oriented stream and wide
-    character input/output functions shall not be applied to a byte-oriented stream. The
-    remaining stream operations do not affect, and are not affected by, a stream's orientation,
-    except for the following additional restrictions:
-    -- Binary wide-oriented streams have the file-positioning restrictions ascribed to both
-      text and binary streams.
-    -- For wide-oriented streams, after a successful call to a file-positioning function that
-      leaves the file position indicator prior to the end-of-file, a wide character output
-      function can overwrite a partial multibyte character; any file contents beyond the
-      byte(s) written are henceforth indeterminate.
-6   Each wide-oriented stream has an associated mbstate_t object that stores the current
-    parse state of the stream. A successful call to fgetpos stores a representation of the
-    value of this mbstate_t object as part of the value of the fpos_t object. A later
-    successful call to fsetpos using the same stored fpos_t value restores the value of
-    the associated mbstate_t object as well as the position within the controlled stream.
-    Environmental limits
-7   An implementation shall support text files with lines containing at least 254 characters,
-    including the terminating new-line character. The value of the macro BUFSIZ shall be at
-    least 256.
-    Forward references: the freopen function (7.21.5.4), the fwide function (7.28.3.5),
-    mbstate_t (7.29.1), the fgetpos function (7.21.9.1), the fsetpos function
-    (7.21.9.3).
-
-
-
-
-    256) The three predefined streams stdin, stdout, and stderr are unoriented at program startup.
-
-[page 298] (Contents)
-
-    7.21.3 Files
-1   A stream is associated with an external file (which may be a physical device) by opening
-    a file, which may involve creating a new file. Creating an existing file causes its former
-    contents to be discarded, if necessary. If a file can support positioning requests (such as a
-    disk file, as opposed to a terminal), then a file position indicator associated with the
-    stream is positioned at the start (character number zero) of the file, unless the file is
-    opened with append mode in which case it is implementation-defined whether the file
-    position indicator is initially positioned at the beginning or the end of the file. The file
-    position indicator is maintained by subsequent reads, writes, and positioning requests, to
-    facilitate an orderly progression through the file.
-2   Binary files are not truncated, except as defined in 7.21.5.3. Whether a write on a text
-    stream causes the associated file to be truncated beyond that point is implementation-
-    defined.
-3   When a stream is unbuffered, characters are intended to appear from the source or at the
-    destination as soon as possible. Otherwise characters may be accumulated and
-    transmitted to or from the host environment as a block. When a stream is fully buffered,
-    characters are intended to be transmitted to or from the host environment as a block when
-    a buffer is filled. When a stream is line buffered, characters are intended to be
-    transmitted to or from the host environment as a block when a new-line character is
-    encountered. Furthermore, characters are intended to be transmitted as a block to the host
-    environment when a buffer is filled, when input is requested on an unbuffered stream, or
-    when input is requested on a line buffered stream that requires the transmission of
-    characters from the host environment. Support for these characteristics is
-    implementation-defined, and may be affected via the setbuf and setvbuf functions.
-4   A file may be disassociated from a controlling stream by closing the file. Output streams
-    are flushed (any unwritten buffer contents are transmitted to the host environment) before
-    the stream is disassociated from the file. The value of a pointer to a FILE object is
-    indeterminate after the associated file is closed (including the standard text streams).
-    Whether a file of zero length (on which no characters have been written by an output
-    stream) actually exists is implementation-defined.
-5   The file may be subsequently reopened, by the same or another program execution, and
-    its contents reclaimed or modified (if it can be repositioned at its start). If the main
-    function returns to its original caller, or if the exit function is called, all open files are
-    closed (hence all output streams are flushed) before program termination. Other paths to
-    program termination, such as calling the abort function, need not close all files
-    properly.
-6   The address of the FILE object used to control a stream may be significant; a copy of a
-    FILE object need not serve in place of the original.
-
-[page 299] (Contents)
-
-7    At program startup, three text streams are predefined and need not be opened explicitly
-     -- standard input (for reading conventional input), standard output (for writing
-     conventional output), and standard error (for writing diagnostic output). As initially
-     opened, the standard error stream is not fully buffered; the standard input and standard
-     output streams are fully buffered if and only if the stream can be determined not to refer
-     to an interactive device.
-8    Functions that open additional (nontemporary) files require a file name, which is a string.
-     The rules for composing valid file names are implementation-defined. Whether the same
-     file can be simultaneously open multiple times is also implementation-defined.
-9    Although both text and binary wide-oriented streams are conceptually sequences of wide
-     characters, the external file associated with a wide-oriented stream is a sequence of
-     multibyte characters, generalized as follows:
-     -- Multibyte encodings within files may contain embedded null bytes (unlike multibyte
-       encodings valid for use internal to the program).
-     -- A file need not begin nor end in the initial shift state.257)
-10   Moreover, the encodings used for multibyte characters may differ among files. Both the
-     nature and choice of such encodings are implementation-defined.
-11   The wide character input functions read multibyte characters from the stream and convert
-     them to wide characters as if they were read by successive calls to the fgetwc function.
-     Each conversion occurs as if by a call to the mbrtowc function, with the conversion state
-     described by the stream's own mbstate_t object. The byte input functions read
-     characters from the stream as if by successive calls to the fgetc function.
-12   The wide character output functions convert wide characters to multibyte characters and
-     write them to the stream as if they were written by successive calls to the fputwc
-     function. Each conversion occurs as if by a call to the wcrtomb function, with the
-     conversion state described by the stream's own mbstate_t object. The byte output
-     functions write characters to the stream as if by successive calls to the fputc function.
-13   In some cases, some of the byte input/output functions also perform conversions between
-     multibyte characters and wide characters. These conversions also occur as if by calls to
-     the mbrtowc and wcrtomb functions.
-14   An encoding error occurs if the character sequence presented to the underlying
-     mbrtowc function does not form a valid (generalized) multibyte character, or if the code
-     value passed to the underlying wcrtomb does not correspond to a valid (generalized)
-
-
-     257) Setting the file position indicator to end-of-file, as with fseek(file, 0, SEEK_END), has
-          undefined behavior for a binary stream (because of possible trailing null characters) or for any stream
-          with state-dependent encoding that does not assuredly end in the initial shift state.
-
-[page 300] (Contents)
-
-     multibyte character. The wide character input/output functions and the byte input/output
-     functions store the value of the macro EILSEQ in errno if and only if an encoding error
-     occurs.
-     Environmental limits
-15   The value of FOPEN_MAX shall be at least eight, including the three standard text
-     streams.
-     Forward references: the exit function (7.22.4.4), the fgetc function (7.21.7.1), the
-     fopen function (7.21.5.3), the fputc function (7.21.7.3), the setbuf function
-     (7.21.5.5), the setvbuf function (7.21.5.6), the fgetwc function (7.28.3.1), the
-     fputwc function (7.28.3.3), conversion state (7.28.6), the mbrtowc function
-     (7.28.6.3.2), the wcrtomb function (7.28.6.3.3).
-     7.21.4 Operations on files
-     7.21.4.1 The remove function
-     Synopsis
-1            #include <stdio.h>
-             int remove(const char *filename);
-     Description
-2    The remove function causes the file whose name is the string pointed to by filename
-     to be no longer accessible by that name. A subsequent attempt to open that file using that
-     name will fail, unless it is created anew. If the file is open, the behavior of the remove
-     function is implementation-defined.
-     Returns
-3    The remove function returns zero if the operation succeeds, nonzero if it fails.
-     7.21.4.2 The rename function
-     Synopsis
-1            #include <stdio.h>
-             int rename(const char *old, const char *new);
-     Description
-2    The rename function causes the file whose name is the string pointed to by old to be
-     henceforth known by the name given by the string pointed to by new. The file named
-     old is no longer accessible by that name. If a file named by the string pointed to by new
-     exists prior to the call to the rename function, the behavior is implementation-defined.
-
-
-
-
-[page 301] (Contents)
-
-    Returns
-3   The rename function returns zero if the operation succeeds, nonzero if it fails,258) in
-    which case if the file existed previously it is still known by its original name.
-    7.21.4.3 The tmpfile function
-    Synopsis
-1           #include <stdio.h>
-            FILE *tmpfile(void);
-    Description
-2   The tmpfile function creates a temporary binary file that is different from any other
-    existing file and that will automatically be removed when it is closed or at program
-    termination. If the program terminates abnormally, whether an open temporary file is
-    removed is implementation-defined. The file is opened for update with "wb+" mode.
-    Recommended practice
-3   It should be possible to open at least TMP_MAX temporary files during the lifetime of the
-    program (this limit may be shared with tmpnam) and there should be no limit on the
-    number simultaneously open other than this limit and any limit on the number of open
-    files (FOPEN_MAX).
-    Returns
-4   The tmpfile function returns a pointer to the stream of the file that it created. If the file
-    cannot be created, the tmpfile function returns a null pointer.
-    Forward references: the fopen function (7.21.5.3).
-    7.21.4.4 The tmpnam function
-    Synopsis
-1           #include <stdio.h>
-            char *tmpnam(char *s);
-    Description
-2   The tmpnam function generates a string that is a valid file name and that is not the same
-    as the name of an existing file.259) The function is potentially capable of generating at
-
-
-    258) Among the reasons the implementation may cause the rename function to fail are that the file is open
-         or that it is necessary to copy its contents to effectuate its renaming.
-    259) Files created using strings generated by the tmpnam function are temporary only in the sense that
-         their names should not collide with those generated by conventional naming rules for the
-         implementation. It is still necessary to use the remove function to remove such files when their use
-         is ended, and before program termination.
-
-[page 302] (Contents)
-
-    least TMP_MAX different strings, but any or all of them may already be in use by existing
-    files and thus not be suitable return values.
-3   The tmpnam function generates a different string each time it is called.
-4   Calls to the tmpnam function with a null pointer argument may introduce data races with
-    each other. The implementation shall behave as if no library function calls the tmpnam
-    function.
-    Returns
-5   If no suitable string can be generated, the tmpnam function returns a null pointer.
-    Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an
-    internal static object and returns a pointer to that object (subsequent calls to the tmpnam
-    function may modify the same object). If the argument is not a null pointer, it is assumed
-    to point to an array of at least L_tmpnam chars; the tmpnam function writes its result
-    in that array and returns the argument as its value.
-    Environmental limits
-6   The value of the macro TMP_MAX shall be at least 25.
-    7.21.5 File access functions
-    7.21.5.1 The fclose function
-    Synopsis
-1           #include <stdio.h>
-            int fclose(FILE *stream);
-    Description
-2   A successful call to the fclose function causes the stream pointed to by stream to be
-    flushed and the associated file to be closed. Any unwritten buffered data for the stream
-    are delivered to the host environment to be written to the file; any unread buffered data
-    are discarded. Whether or not the call succeeds, the stream is disassociated from the file
-    and any buffer set by the setbuf or setvbuf function is disassociated from the stream
-    (and deallocated if it was automatically allocated).
-    Returns
-3   The fclose function returns zero if the stream was successfully closed, or EOF if any
-    errors were detected.
-
-
-
-
-[page 303] (Contents)
-
-    7.21.5.2 The fflush function
-    Synopsis
-1           #include <stdio.h>
-            int fflush(FILE *stream);
-    Description
-2   If stream points to an output stream or an update stream in which the most recent
-    operation was not input, the fflush function causes any unwritten data for that stream
-    to be delivered to the host environment to be written to the file; otherwise, the behavior is
-    undefined.
-3   If stream is a null pointer, the fflush function performs this flushing action on all
-    streams for which the behavior is defined above.
-    Returns
-4   The fflush function sets the error indicator for the stream and returns EOF if a write
-    error occurs, otherwise it returns zero.
-    Forward references: the fopen function (7.21.5.3).
-    7.21.5.3 The fopen function
-    Synopsis
-1           #include <stdio.h>
-            FILE *fopen(const char * restrict filename,
-                 const char * restrict mode);
-    Description
-2   The fopen function opens the file whose name is the string pointed to by filename,
-    and associates a stream with it.
-3   The argument mode points to a string. If the string is one of the following, the file is
-    open in the indicated mode. Otherwise, the behavior is undefined.260)
-    r                     open text file for reading
-    w                     truncate to zero length or create text file for writing
-    wx                    create text file for writing
-    a                     append; open or create text file for writing at end-of-file
-    rb                    open binary file for reading
-    wb                    truncate to zero length or create binary file for writing
-
-
-    260) If the string begins with one of the above sequences, the implementation might choose to ignore the
-         remaining characters, or it might use them to select different kinds of a file (some of which might not
-         conform to the properties in 7.21.2).
-
-[page 304] (Contents)
-
-    wbx               create binary file for writing
-    ab                append; open or create binary file for writing at end-of-file
-    r+                open text file for update (reading and writing)
-    w+                truncate to zero length or create text file for update
-    w+x               create text file for update
-    a+                append; open or create text file for update, writing at end-of-file
-    r+b or rb+        open binary file for update (reading and writing)
-    w+b or wb+        truncate to zero length or create binary file for update
-    w+bx or wb+x      create binary file for update
-    a+b or ab+        append; open or create binary file for update, writing at end-of-file
-4   Opening a file with read mode ('r' as the first character in the mode argument) fails if
-    the file does not exist or cannot be read.
-5   Opening a file with exclusive mode ('x' as the last character in the mode argument)
-    fails if the file already exists or cannot be created. Otherwise, the file is created with
-    exclusive (also known as non-shared) access to the extent that the underlying system
-    supports exclusive access.
-6   Opening a file with append mode ('a' as the first character in the mode argument)
-    causes all subsequent writes to the file to be forced to the then current end-of-file,
-    regardless of intervening calls to the fseek function. In some implementations, opening
-    a binary file with append mode ('b' as the second or third character in the above list of
-    mode argument values) may initially position the file position indicator for the stream
-    beyond the last data written, because of null character padding.
-7   When a file is opened with update mode ('+' as the second or third character in the
-    above list of mode argument values), both input and output may be performed on the
-    associated stream. However, output shall not be directly followed by input without an
-    intervening call to the fflush function or to a file positioning function (fseek,
-    fsetpos, or rewind), and input shall not be directly followed by output without an
-    intervening call to a file positioning function, unless the input operation encounters end-
-    of-file. Opening (or creating) a text file with update mode may instead open (or create) a
-    binary stream in some implementations.
-8   When opened, a stream is fully buffered if and only if it can be determined not to refer to
-    an interactive device. The error and end-of-file indicators for the stream are cleared.
-    Returns
-9   The fopen function returns a pointer to the object controlling the stream. If the open
-    operation fails, fopen returns a null pointer.
-    Forward references: file positioning functions (7.21.9).
-
-
-
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-
-    7.21.5.4 The freopen function
-    Synopsis
-1           #include <stdio.h>
-            FILE *freopen(const char * restrict filename,
-                 const char * restrict mode,
-                 FILE * restrict stream);
-    Description
-2   The freopen function opens the file whose name is the string pointed to by filename
-    and associates the stream pointed to by stream with it. The mode argument is used just
-    as in the fopen function.261)
-3   If filename is a null pointer, the freopen function attempts to change the mode of
-    the stream to that specified by mode, as if the name of the file currently associated with
-    the stream had been used. It is implementation-defined which changes of mode are
-    permitted (if any), and under what circumstances.
-4   The freopen function first attempts to close any file that is associated with the specified
-    stream. Failure to close the file is ignored. The error and end-of-file indicators for the
-    stream are cleared.
-    Returns
-5   The freopen function returns a null pointer if the open operation fails. Otherwise,
-    freopen returns the value of stream.
-    7.21.5.5 The setbuf function
-    Synopsis
-1           #include <stdio.h>
-            void setbuf(FILE * restrict stream,
-                 char * restrict buf);
-    Description
-2   Except that it returns no value, the setbuf function is equivalent to the setvbuf
-    function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf
-    is a null pointer), with the value _IONBF for mode.
-
-
-
-
-    261) The primary use of the freopen function is to change the file associated with a standard text stream
-         (stderr, stdin, or stdout), as those identifiers need not be modifiable lvalues to which the value
-         returned by the fopen function may be assigned.
-
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-
-    Returns
-3   The setbuf function returns no value.
-    Forward references: the setvbuf function (7.21.5.6).
-    7.21.5.6 The setvbuf function
-    Synopsis
-1           #include <stdio.h>
-            int setvbuf(FILE * restrict stream,
-                 char * restrict buf,
-                 int mode, size_t size);
-    Description
-2   The setvbuf function may be used only after the stream pointed to by stream has
-    been associated with an open file and before any other operation (other than an
-    unsuccessful call to setvbuf) is performed on the stream. The argument mode
-    determines how stream will be buffered, as follows: _IOFBF causes input/output to be
-    fully buffered; _IOLBF causes input/output to be line buffered; _IONBF causes
-    input/output to be unbuffered. If buf is not a null pointer, the array it points to may be
-    used instead of a buffer allocated by the setvbuf function262) and the argument size
-    specifies the size of the array; otherwise, size may determine the size of a buffer
-    allocated by the setvbuf function. The contents of the array at any time are
-    indeterminate.
-    Returns
-3   The setvbuf function returns zero on success, or nonzero if an invalid value is given
-    for mode or if the request cannot be honored.
-
-
-
-
-    262) The buffer has to have a lifetime at least as great as the open stream, so the stream should be closed
-         before a buffer that has automatic storage duration is deallocated upon block exit.
-
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-
-    7.21.6 Formatted input/output functions
-1   The formatted input/output functions shall behave as if there is a sequence point after the
-    actions associated with each specifier.263)
-    7.21.6.1 The fprintf function
-    Synopsis
-1            #include <stdio.h>
-             int fprintf(FILE * restrict stream,
-                  const char * restrict format, ...);
-    Description
-2   The fprintf function writes output to the stream pointed to by stream, under control
-    of the string pointed to by format that specifies how subsequent arguments are
-    converted for output. If there are insufficient arguments for the format, the behavior is
-    undefined. If the format is exhausted while arguments remain, the excess arguments are
-    evaluated (as always) but are otherwise ignored. The fprintf function returns when
-    the end of the format string is encountered.
-3   The format shall be a multibyte character sequence, beginning and ending in its initial
-    shift state. The format is composed of zero or more directives: ordinary multibyte
-    characters (not %), which are copied unchanged to the output stream; and conversion
-    specifications, each of which results in fetching zero or more subsequent arguments,
-    converting them, if applicable, according to the corresponding conversion specifier, and
-    then writing the result to the output stream.
-4   Each conversion specification is introduced by the character %. After the %, the following
-    appear in sequence:
-    -- Zero or more flags (in any order) that modify the meaning of the conversion
-      specification.
-    -- An optional minimum field width. If the converted value has fewer characters than the
-      field width, it is padded with spaces (by default) on the left (or right, if the left
-      adjustment flag, described later, has been given) to the field width. The field width
-      takes the form of an asterisk * (described later) or a nonnegative decimal integer.264)
-    -- An optional precision that gives the minimum number of digits to appear for the d, i,
-      o, u, x, and X conversions, the number of digits to appear after the decimal-point
-      character for a, A, e, E, f, and F conversions, the maximum number of significant
-      digits for the g and G conversions, or the maximum number of bytes to be written for
-
-
-    263) The fprintf functions perform writes to memory for the %n specifier.
-    264) Note that 0 is taken as a flag, not as the beginning of a field width.
-
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-
-        s conversions. The precision takes the form of a period (.) followed either by an
-        asterisk * (described later) or by an optional decimal integer; if only the period is
-        specified, the precision is taken as zero. If a precision appears with any other
-        conversion specifier, the behavior is undefined.
-    -- An optional length modifier that specifies the size of the argument.
-    -- A conversion specifier character that specifies the type of conversion to be applied.
-5   As noted above, a field width, or precision, or both, may be indicated by an asterisk. In
-    this case, an int argument supplies the field width or precision. The arguments
-    specifying field width, or precision, or both, shall appear (in that order) before the
-    argument (if any) to be converted. A negative field width argument is taken as a - flag
-    followed by a positive field width. A negative precision argument is taken as if the
-    precision were omitted.
-6   The flag characters and their meanings are:
-    -       The result of the conversion is left-justified within the field. (It is right-justified if
-            this flag is not specified.)
-    +       The result of a signed conversion always begins with a plus or minus sign. (It
-            begins with a sign only when a negative value is converted if this flag is not
-            specified.)265)
-    space If the first character of a signed conversion is not a sign, or if a signed conversion
-          results in no characters, a space is prefixed to the result. If the space and + flags
-          both appear, the space flag is ignored.
-    #       The result is converted to an ''alternative form''. For o conversion, it increases
-            the precision, if and only if necessary, to force the first digit of the result to be a
-            zero (if the value and precision are both 0, a single 0 is printed). For x (or X)
-            conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,
-            and G conversions, the result of converting a floating-point number always
-            contains a decimal-point character, even if no digits follow it. (Normally, a
-            decimal-point character appears in the result of these conversions only if a digit
-            follows it.) For g and G conversions, trailing zeros are not removed from the
-            result. For other conversions, the behavior is undefined.
-    0       For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-            (following any indication of sign or base) are used to pad to the field width rather
-            than performing space padding, except when converting an infinity or NaN. If the
-            0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X
-
-
-    265) The results of all floating conversions of a negative zero, and of negative values that round to zero,
-         include a minus sign.
-
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-
-              conversions, if a precision is specified, the 0 flag is ignored. For other
-              conversions, the behavior is undefined.
-7   The length modifiers and their meanings are:
-    hh            Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                  signed char or unsigned char argument (the argument will have
-                  been promoted according to the integer promotions, but its value shall be
-                  converted to signed char or unsigned char before printing); or that
-                  a following n conversion specifier applies to a pointer to a signed char
-                  argument.
-    h             Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                  short int or unsigned short int argument (the argument will
-                  have been promoted according to the integer promotions, but its value shall
-                  be converted to short int or unsigned short int before printing);
-                  or that a following n conversion specifier applies to a pointer to a short
-                  int argument.
-    l (ell)       Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                  long int or unsigned long int argument; that a following n
-                  conversion specifier applies to a pointer to a long int argument; that a
-                  following c conversion specifier applies to a wint_t argument; that a
-                  following s conversion specifier applies to a pointer to a wchar_t
-                  argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion
-                  specifier.
-    ll (ell-ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                 long long int or unsigned long long int argument; or that a
-                 following n conversion specifier applies to a pointer to a long long int
-                 argument.
-    j             Specifies that a following d, i, o, u, x, or X conversion specifier applies to
-                  an intmax_t or uintmax_t argument; or that a following n conversion
-                  specifier applies to a pointer to an intmax_t argument.
-    z             Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                  size_t or the corresponding signed integer type argument; or that a
-                  following n conversion specifier applies to a pointer to a signed integer type
-                  corresponding to size_t argument.
-    t             Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                  ptrdiff_t or the corresponding unsigned integer type argument; or that a
-                  following n conversion specifier applies to a pointer to a ptrdiff_t
-                  argument.
-
-
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-
-    L              Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-                   applies to a long double argument.
-    If a length modifier appears with any conversion specifier other than as specified above,
-    the behavior is undefined.
-8   The conversion specifiers and their meanings are:
-    d,i          The int argument is converted to signed decimal in the style [-]dddd. The
-                 precision specifies the minimum number of digits to appear; if the value
-                 being converted can be represented in fewer digits, it is expanded with
-                 leading zeros. The default precision is 1. The result of converting a zero
-                 value with a precision of zero is no characters.
-    o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned
-            decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the
-            letters abcdef are used for x conversion and the letters ABCDEF for X
-            conversion. The precision specifies the minimum number of digits to appear;
-            if the value being converted can be represented in fewer digits, it is expanded
-            with leading zeros. The default precision is 1. The result of converting a
-            zero value with a precision of zero is no characters.
-    f,F          A double argument representing a floating-point number is converted to
-                 decimal notation in the style [-]ddd.ddd, where the number of digits after
-                 the decimal-point character is equal to the precision specification. If the
-                 precision is missing, it is taken as 6; if the precision is zero and the # flag is
-                 not specified, no decimal-point character appears. If a decimal-point
-                 character appears, at least one digit appears before it. The value is rounded to
-                 the appropriate number of digits.
-                 A double argument representing an infinity is converted in one of the styles
-                 [-]inf or [-]infinity -- which style is implementation-defined. A
-                 double argument representing a NaN is converted in one of the styles
-                 [-]nan or [-]nan(n-char-sequence) -- which style, and the meaning of
-                 any n-char-sequence, is implementation-defined. The F conversion specifier
-                 produces INF, INFINITY, or NAN instead of inf, infinity, or nan,
-                 respectively.266)
-    e,E          A double argument representing a floating-point number is converted in the
-                 style [-]d.ddd e(+-)dd, where there is one digit (which is nonzero if the
-                 argument is nonzero) before the decimal-point character and the number of
-                 digits after it is equal to the precision; if the precision is missing, it is taken as
-
-
-    266) When applied to infinite and NaN values, the -, +, and space flag characters have their usual meaning;
-         the # and 0 flag characters have no effect.
-
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-
-              6; if the precision is zero and the # flag is not specified, no decimal-point
-              character appears. The value is rounded to the appropriate number of digits.
-              The E conversion specifier produces a number with E instead of e
-              introducing the exponent. The exponent always contains at least two digits,
-              and only as many more digits as necessary to represent the exponent. If the
-              value is zero, the exponent is zero.
-              A double argument representing an infinity or NaN is converted in the style
-              of an f or F conversion specifier.
-g,G           A double argument representing a floating-point number is converted in
-              style f or e (or in style F or E in the case of a G conversion specifier),
-              depending on the value converted and the precision. Let P equal the
-              precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero.
-              Then, if a conversion with style E would have an exponent of X:
-              -- if P > X >= -4, the conversion is with style f (or F) and precision
-                P - (X + 1).
-              -- otherwise, the conversion is with style e (or E) and precision P - 1.
-              Finally, unless the # flag is used, any trailing zeros are removed from the
-              fractional portion of the result and the decimal-point character is removed if
-              there is no fractional portion remaining.
-              A double argument representing an infinity or NaN is converted in the style
-              of an f or F conversion specifier.
-a,A           A double argument representing a floating-point number is converted in the
-              style [-]0xh.hhhh p(+-)d, where there is one hexadecimal digit (which is
-              nonzero if the argument is a normalized floating-point number and is
-              otherwise unspecified) before the decimal-point character267) and the number
-              of hexadecimal digits after it is equal to the precision; if the precision is
-              missing and FLT_RADIX is a power of 2, then the precision is sufficient for
-              an exact representation of the value; if the precision is missing and
-              FLT_RADIX is not a power of 2, then the precision is sufficient to
-
-
-
-
-267) Binary implementations can choose the hexadecimal digit to the left of the decimal-point character so
-     that subsequent digits align to nibble (4-bit) boundaries.
-
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-
-              distinguish268) values of type double, except that trailing zeros may be
-              omitted; if the precision is zero and the # flag is not specified, no decimal-
-              point character appears. The letters abcdef are used for a conversion and
-              the letters ABCDEF for A conversion. The A conversion specifier produces a
-              number with X and P instead of x and p. The exponent always contains at
-              least one digit, and only as many more digits as necessary to represent the
-              decimal exponent of 2. If the value is zero, the exponent is zero.
-              A double argument representing an infinity or NaN is converted in the style
-              of an f or F conversion specifier.
-c             If no l length modifier is present, the int argument is converted to an
-              unsigned char, and the resulting character is written.
-              If an l length modifier is present, the wint_t argument is converted as if by
-              an ls conversion specification with no precision and an argument that points
-              to the initial element of a two-element array of wchar_t, the first element
-              containing the wint_t argument to the lc conversion specification and the
-              second a null wide character.
-s             If no l length modifier is present, the argument shall be a pointer to the initial
-              element of an array of character type.269) Characters from the array are
-              written up to (but not including) the terminating null character. If the
-              precision is specified, no more than that many bytes are written. If the
-              precision is not specified or is greater than the size of the array, the array shall
-              contain a null character.
-              If an l length modifier is present, the argument shall be a pointer to the initial
-              element of an array of wchar_t type. Wide characters from the array are
-              converted to multibyte characters (each as if by a call to the wcrtomb
-              function, with the conversion state described by an mbstate_t object
-              initialized to zero before the first wide character is converted) up to and
-              including a terminating null wide character. The resulting multibyte
-              characters are written up to (but not including) the terminating null character
-              (byte). If no precision is specified, the array shall contain a null wide
-              character. If a precision is specified, no more than that many bytes are
-              written (including shift sequences, if any), and the array shall contain a null
-              wide character if, to equal the multibyte character sequence length given by
-
-268) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
-     FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p
-     might suffice depending on the implementation's scheme for determining the digit to the left of the
-     decimal-point character.
-269) No special provisions are made for multibyte characters.
-
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-
-                    the precision, the function would need to access a wide character one past the
-                    end of the array. In no case is a partial multibyte character written.270)
-     p              The argument shall be a pointer to void. The value of the pointer is
-                    converted to a sequence of printing characters, in an implementation-defined
-                    manner.
-     n              The argument shall be a pointer to signed integer into which is written the
-                    number of characters written to the output stream so far by this call to
-                    fprintf. No argument is converted, but one is consumed. If the conversion
-                    specification includes any flags, a field width, or a precision, the behavior is
-                    undefined.
-     %              A % character is written. No argument is converted. The complete
-                    conversion specification shall be %%.
-9    If a conversion specification is invalid, the behavior is undefined.271) If any argument is
-     not the correct type for the corresponding conversion specification, the behavior is
-     undefined.
-10   In no case does a nonexistent or small field width cause truncation of a field; if the result
-     of a conversion is wider than the field width, the field is expanded to contain the
-     conversion result.
-11   For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
-     to a hexadecimal floating number with the given precision.
-     Recommended practice
-12   For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
-     representable in the given precision, the result should be one of the two adjacent numbers
-     in hexadecimal floating style with the given precision, with the extra stipulation that the
-     error should have a correct sign for the current rounding direction.
-13   For e, E, f, F, g, and G conversions, if the number of significant decimal digits is at most
-     DECIMAL_DIG, then the result should be correctly rounded.272) If the number of
-     significant decimal digits is more than DECIMAL_DIG but the source value is exactly
-     representable with DECIMAL_DIG digits, then the result should be an exact
-     representation with trailing zeros. Otherwise, the source value is bounded by two
-     adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value
-
-
-     270) Redundant shift sequences may result if multibyte characters have a state-dependent encoding.
-     271) See ''future library directions'' (7.30.9).
-     272) For binary-to-decimal conversion, the result format's values are the numbers representable with the
-          given format specifier. The number of significant digits is determined by the format specifier, and in
-          the case of fixed-point conversion by the source value as well.
-
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-
-     of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
-     the error should have a correct sign for the current rounding direction.
-     Returns
-14   The fprintf function returns the number of characters transmitted, or a negative value
-     if an output or encoding error occurred.
-     Environmental limits
-15   The number of characters that can be produced by any single conversion shall be at least
-     4095.
-16   EXAMPLE 1         To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal
-     places:
-              #include <math.h>
-              #include <stdio.h>
-              /* ... */
-              char *weekday, *month;      // pointers to strings
-              int day, hour, min;
-              fprintf(stdout, "%s, %s %d, %.2d:%.2d\n",
-                      weekday, month, day, hour, min);
-              fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));
-
-17   EXAMPLE 2 In this example, multibyte characters do not have a state-dependent encoding, and the
-     members of the extended character set that consist of more than one byte each consist of exactly two bytes,
-     the first of which is denoted here by a and the second by an uppercase letter.
-18   Given the following wide string with length seven,
-              static wchar_t wstr[] = L" X Yabc Z W";
-     the seven calls
-              fprintf(stdout,          "|1234567890123|\n");
-              fprintf(stdout,          "|%13ls|\n", wstr);
-              fprintf(stdout,          "|%-13.9ls|\n", wstr);
-              fprintf(stdout,          "|%13.10ls|\n", wstr);
-              fprintf(stdout,          "|%13.11ls|\n", wstr);
-              fprintf(stdout,          "|%13.15ls|\n", &wstr[2]);
-              fprintf(stdout,          "|%13lc|\n", (wint_t) wstr[5]);
-     will print the following seven lines:
-              |1234567890123|
-              |   X Yabc Z W|
-              | X Yabc Z    |
-              |     X Yabc Z|
-              |   X Yabc Z W|
-              |      abc Z W|
-              |            Z|
-
-     Forward references: conversion state (7.28.6), the wcrtomb function (7.28.6.3.3).
-
-
-
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-
-    7.21.6.2 The fscanf function
-    Synopsis
-1          #include <stdio.h>
-           int fscanf(FILE * restrict stream,
-                const char * restrict format, ...);
-    Description
-2   The fscanf function reads input from the stream pointed to by stream, under control
-    of the string pointed to by format that specifies the admissible input sequences and how
-    they are to be converted for assignment, using subsequent arguments as pointers to the
-    objects to receive the converted input. If there are insufficient arguments for the format,
-    the behavior is undefined. If the format is exhausted while arguments remain, the excess
-    arguments are evaluated (as always) but are otherwise ignored.
-3   The format shall be a multibyte character sequence, beginning and ending in its initial
-    shift state. The format is composed of zero or more directives: one or more white-space
-    characters, an ordinary multibyte character (neither % nor a white-space character), or a
-    conversion specification. Each conversion specification is introduced by the character %.
-    After the %, the following appear in sequence:
-    -- An optional assignment-suppressing character *.
-    -- An optional decimal integer greater than zero that specifies the maximum field width
-      (in characters).
-    -- An optional length modifier that specifies the size of the receiving object.
-    -- A conversion specifier character that specifies the type of conversion to be applied.
-4   The fscanf function executes each directive of the format in turn. When all directives
-    have been executed, or if a directive fails (as detailed below), the function returns.
-    Failures are described as input failures (due to the occurrence of an encoding error or the
-    unavailability of input characters), or matching failures (due to inappropriate input).
-5   A directive composed of white-space character(s) is executed by reading input up to the
-    first non-white-space character (which remains unread), or until no more characters can
-    be read.
-6   A directive that is an ordinary multibyte character is executed by reading the next
-    characters of the stream. If any of those characters differ from the ones composing the
-    directive, the directive fails and the differing and subsequent characters remain unread.
-    Similarly, if end-of-file, an encoding error, or a read error prevents a character from being
-    read, the directive fails.
-7   A directive that is a conversion specification defines a set of matching input sequences, as
-    described below for each specifier. A conversion specification is executed in the
-
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-
-     following steps:
-8    Input white-space characters (as specified by the isspace function) are skipped, unless
-     the specification includes a [, c, or n specifier.273)
-9    An input item is read from the stream, unless the specification includes an n specifier. An
-     input item is defined as the longest sequence of input characters which does not exceed
-     any specified field width and which is, or is a prefix of, a matching input sequence.274)
-     The first character, if any, after the input item remains unread. If the length of the input
-     item is zero, the execution of the directive fails; this condition is a matching failure unless
-     end-of-file, an encoding error, or a read error prevented input from the stream, in which
-     case it is an input failure.
-10   Except in the case of a % specifier, the input item (or, in the case of a %n directive, the
-     count of input characters) is converted to a type appropriate to the conversion specifier. If
-     the input item is not a matching sequence, the execution of the directive fails: this
-     condition is a matching failure. Unless assignment suppression was indicated by a *, the
-     result of the conversion is placed in the object pointed to by the first argument following
-     the format argument that has not already received a conversion result. If this object
-     does not have an appropriate type, or if the result of the conversion cannot be represented
-     in the object, the behavior is undefined.
-11   The length modifiers and their meanings are:
-     hh             Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                    to an argument with type pointer to signed char or unsigned char.
-     h              Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                    to an argument with type pointer to short int or unsigned short
-                    int.
-     l (ell)        Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                    to an argument with type pointer to long int or unsigned long
-                    int; that a following a, A, e, E, f, F, g, or G conversion specifier applies to
-                    an argument with type pointer to double; or that a following c, s, or [
-                    conversion specifier applies to an argument with type pointer to wchar_t.
-     ll (ell-ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                  to an argument with type pointer to long long int or unsigned
-                  long long int.
-
-
-
-     273) These white-space characters are not counted against a specified field width.
-     274) fscanf pushes back at most one input character onto the input stream. Therefore, some sequences
-          that are acceptable to strtod, strtol, etc., are unacceptable to fscanf.
-
-[page 317] (Contents)
-
-     j           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to intmax_t or uintmax_t.
-     z           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to size_t or the corresponding signed
-                 integer type.
-     t           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to ptrdiff_t or the corresponding
-                 unsigned integer type.
-     L           Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-                 applies to an argument with type pointer to long double.
-     If a length modifier appears with any conversion specifier other than as specified above,
-     the behavior is undefined.
-12   The conversion specifiers and their meanings are:
-     d          Matches an optionally signed decimal integer, whose format is the same as
-                expected for the subject sequence of the strtol function with the value 10
-                for the base argument. The corresponding argument shall be a pointer to
-                signed integer.
-     i          Matches an optionally signed integer, whose format is the same as expected
-                for the subject sequence of the strtol function with the value 0 for the
-                base argument. The corresponding argument shall be a pointer to signed
-                integer.
-     o          Matches an optionally signed octal integer, whose format is the same as
-                expected for the subject sequence of the strtoul function with the value 8
-                for the base argument. The corresponding argument shall be a pointer to
-                unsigned integer.
-     u          Matches an optionally signed decimal integer, whose format is the same as
-                expected for the subject sequence of the strtoul function with the value 10
-                for the base argument. The corresponding argument shall be a pointer to
-                unsigned integer.
-     x          Matches an optionally signed hexadecimal integer, whose format is the same
-                as expected for the subject sequence of the strtoul function with the value
-                16 for the base argument. The corresponding argument shall be a pointer to
-                unsigned integer.
-     a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose
-             format is the same as expected for the subject sequence of the strtod
-             function. The corresponding argument shall be a pointer to floating.
-
-
-[page 318] (Contents)
-
-c             Matches a sequence of characters of exactly the number specified by the field
-              width (1 if no field width is present in the directive).275)
-              If no l length modifier is present, the corresponding argument shall be a
-              pointer to the initial element of a character array large enough to accept the
-              sequence. No null character is added.
-              If an l length modifier is present, the input shall be a sequence of multibyte
-              characters that begins in the initial shift state. Each multibyte character in the
-              sequence is converted to a wide character as if by a call to the mbrtowc
-              function, with the conversion state described by an mbstate_t object
-              initialized to zero before the first multibyte character is converted. The
-              corresponding argument shall be a pointer to the initial element of an array of
-              wchar_t large enough to accept the resulting sequence of wide characters.
-              No null wide character is added.
-s             Matches a sequence of non-white-space characters.275)
-              If no l length modifier is present, the corresponding argument shall be a
-              pointer to the initial element of a character array large enough to accept the
-              sequence and a terminating null character, which will be added automatically.
-              If an l length modifier is present, the input shall be a sequence of multibyte
-              characters that begins in the initial shift state. Each multibyte character is
-              converted to a wide character as if by a call to the mbrtowc function, with
-              the conversion state described by an mbstate_t object initialized to zero
-              before the first multibyte character is converted. The corresponding argument
-              shall be a pointer to the initial element of an array of wchar_t large enough
-              to accept the sequence and the terminating null wide character, which will be
-              added automatically.
-[             Matches a nonempty sequence of characters from a set of expected characters
-              (the scanset).275)
-              If no l length modifier is present, the corresponding argument shall be a
-              pointer to the initial element of a character array large enough to accept the
-              sequence and a terminating null character, which will be added automatically.
-              If an l length modifier is present, the input shall be a sequence of multibyte
-              characters that begins in the initial shift state. Each multibyte character is
-              converted to a wide character as if by a call to the mbrtowc function, with
-              the conversion state described by an mbstate_t object initialized to zero
-
-275) No special provisions are made for multibyte characters in the matching rules used by the c, s, and [
-     conversion specifiers -- the extent of the input field is determined on a byte-by-byte basis. The
-     resulting field is nevertheless a sequence of multibyte characters that begins in the initial shift state.
-
-[page 319] (Contents)
-
-                    before the first multibyte character is converted. The corresponding argument
-                    shall be a pointer to the initial element of an array of wchar_t large enough
-                    to accept the sequence and the terminating null wide character, which will be
-                    added automatically.
-                    The conversion specifier includes all subsequent characters in the format
-                    string, up to and including the matching right bracket (]). The characters
-                    between the brackets (the scanlist) compose the scanset, unless the character
-                    after the left bracket is a circumflex (^), in which case the scanset contains all
-                    characters that do not appear in the scanlist between the circumflex and the
-                    right bracket. If the conversion specifier begins with [] or [^], the right
-                    bracket character is in the scanlist and the next following right bracket
-                    character is the matching right bracket that ends the specification; otherwise
-                    the first following right bracket character is the one that ends the
-                    specification. If a - character is in the scanlist and is not the first, nor the
-                    second where the first character is a ^, nor the last character, the behavior is
-                    implementation-defined.
-     p              Matches an implementation-defined set of sequences, which should be the
-                    same as the set of sequences that may be produced by the %p conversion of
-                    the fprintf function. The corresponding argument shall be a pointer to a
-                    pointer to void. The input item is converted to a pointer value in an
-                    implementation-defined manner. If the input item is a value converted earlier
-                    during the same program execution, the pointer that results shall compare
-                    equal to that value; otherwise the behavior of the %p conversion is undefined.
-     n              No input is consumed. The corresponding argument shall be a pointer to
-                    signed integer into which is to be written the number of characters read from
-                    the input stream so far by this call to the fscanf function. Execution of a
-                    %n directive does not increment the assignment count returned at the
-                    completion of execution of the fscanf function. No argument is converted,
-                    but one is consumed. If the conversion specification includes an assignment-
-                    suppressing character or a field width, the behavior is undefined.
-     %              Matches a single % character; no conversion or assignment occurs. The
-                    complete conversion specification shall be %%.
-13   If a conversion specification is invalid, the behavior is undefined.276)
-14   The conversion specifiers A, E, F, G, and X are also valid and behave the same as,
-     respectively, a, e, f, g, and x.
-
-
-
-     276) See ''future library directions'' (7.30.9).
-
-[page 320] (Contents)
-
-15   Trailing white space (including new-line characters) is left unread unless matched by a
-     directive. The success of literal matches and suppressed assignments is not directly
-     determinable other than via the %n directive.
-     Returns
-16   The fscanf function returns the value of the macro EOF if an input failure occurs
-     before the first conversion (if any) has completed. Otherwise, the function returns the
-     number of input items assigned, which can be fewer than provided for, or even zero, in
-     the event of an early matching failure.
-17   EXAMPLE 1        The call:
-              #include <stdio.h>
-              /* ... */
-              int n, i; float x; char name[50];
-              n = fscanf(stdin, "%d%f%s", &i, &x, name);
-     with the input line:
-              25 54.32E-1 thompson
-     will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
-     thompson\0.
-
-18   EXAMPLE 2        The call:
-              #include <stdio.h>
-              /* ... */
-              int i; float x; char name[50];
-              fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name);
-     with input:
-              56789 0123 56a72
-     will assign to i the value 56 and to x the value 789.0, will skip 0123, and will assign to name the
-     sequence 56\0. The next character read from the input stream will be a.
-
-19   EXAMPLE 3        To accept repeatedly from stdin a quantity, a unit of measure, and an item name:
-              #include <stdio.h>
-              /* ... */
-              int count; float quant; char units[21], item[21];
-              do {
-                      count = fscanf(stdin, "%f%20s of %20s", &quant, units, item);
-                      fscanf(stdin,"%*[^\n]");
-              } while (!feof(stdin) && !ferror(stdin));
-20   If the stdin stream contains the following lines:
-              2 quarts of oil
-              -12.8degrees Celsius
-              lots of luck
-              10.0LBS     of
-              dirt
-              100ergs of energy
-
-[page 321] (Contents)
-
-     the execution of the above example will be analogous to the following assignments:
-               quant     =   2; strcpy(units, "quarts"); strcpy(item, "oil");
-               count     =   3;
-               quant     =   -12.8; strcpy(units, "degrees");
-               count     =   2; // "C" fails to match "o"
-               count     =   0; // "l" fails to match "%f"
-               quant     =   10.0; strcpy(units, "LBS"); strcpy(item, "dirt");
-               count     =   3;
-               count     =   0; // "100e" fails to match "%f"
-               count     =   EOF;
-
-21   EXAMPLE 4         In:
-               #include <stdio.h>
-               /* ... */
-               int d1, d2, n1, n2, i;
-               i = sscanf("123", "%d%n%n%d", &d1, &n1, &n2, &d2);
-     the value 123 is assigned to d1 and the value 3 to n1. Because %n can never get an input failure the value
-     of 3 is also assigned to n2. The value of d2 is not affected. The value 1 is assigned to i.
-
-22   EXAMPLE 5 In these examples, multibyte characters do have a state-dependent encoding, and the
-     members of the extended character set that consist of more than one byte each consist of exactly two bytes,
-     the first of which is denoted here by a and the second by an uppercase letter, but are only recognized as
-     such when in the alternate shift state. The shift sequences are denoted by (uparrow) and (downarrow), in which the first causes
-     entry into the alternate shift state.
-23   After the call:
-               #include <stdio.h>
-               /* ... */
-               char str[50];
-               fscanf(stdin, "a%s", str);
-     with the input line:
-               a(uparrow) X Y(downarrow) bc
-     str will contain (uparrow) X Y(downarrow)\0 assuming that none of the bytes of the shift sequences (or of the multibyte
-     characters, in the more general case) appears to be a single-byte white-space character.
-24   In contrast, after the call:
-               #include <stdio.h>
-               #include <stddef.h>
-               /* ... */
-               wchar_t wstr[50];
-               fscanf(stdin, "a%ls", wstr);
-     with the same input line, wstr will contain the two wide characters that correspond to X and Y and a
-     terminating null wide character.
-25   However, the call:
-
-
-
-
-[page 322] (Contents)
-
-             #include <stdio.h>
-             #include <stddef.h>
-             /* ... */
-             wchar_t wstr[50];
-             fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr);
-     with the same input line will return zero due to a matching failure against the (downarrow) sequence in the format
-     string.
-26   Assuming that the first byte of the multibyte character X is the same as the first byte of the multibyte
-     character Y, after the call:
-             #include <stdio.h>
-             #include <stddef.h>
-             /* ... */
-             wchar_t wstr[50];
-             fscanf(stdin, "a(uparrow) Y(downarrow)%ls", wstr);
-     with the same input line, zero will again be returned, but stdin will be left with a partially consumed
-     multibyte character.
-
-     Forward references: the strtod, strtof, and strtold functions (7.22.1.3), the
-     strtol, strtoll, strtoul, and strtoull functions (7.22.1.4), conversion state
-     (7.28.6), the wcrtomb function (7.28.6.3.3).
-     7.21.6.3 The printf function
-     Synopsis
-1            #include <stdio.h>
-             int printf(const char * restrict format, ...);
-     Description
-2    The printf function is equivalent to fprintf with the argument stdout interposed
-     before the arguments to printf.
-     Returns
-3    The printf function returns the number of characters transmitted, or a negative value if
-     an output or encoding error occurred.
-     7.21.6.4 The scanf function
-     Synopsis
-1            #include <stdio.h>
-             int scanf(const char * restrict format, ...);
-     Description
-2    The scanf function is equivalent to fscanf with the argument stdin interposed
-     before the arguments to scanf.
-
-
-
-[page 323] (Contents)
-
-    Returns
-3   The scanf function returns the value of the macro EOF if an input failure occurs before
-    the first conversion (if any) has completed. Otherwise, the scanf function returns the
-    number of input items assigned, which can be fewer than provided for, or even zero, in
-    the event of an early matching failure.
-    7.21.6.5 The snprintf function
-    Synopsis
-1          #include <stdio.h>
-           int snprintf(char * restrict s, size_t n,
-                const char * restrict format, ...);
-    Description
-2   The snprintf function is equivalent to fprintf, except that the output is written into
-    an array (specified by argument s) rather than to a stream. If n is zero, nothing is written,
-    and s may be a null pointer. Otherwise, output characters beyond the n-1st are
-    discarded rather than being written to the array, and a null character is written at the end
-    of the characters actually written into the array. If copying takes place between objects
-    that overlap, the behavior is undefined.
-    Returns
-3   The snprintf function returns the number of characters that would have been written
-    had n been sufficiently large, not counting the terminating null character, or a negative
-    value if an encoding error occurred. Thus, the null-terminated output has been
-    completely written if and only if the returned value is nonnegative and less than n.
-    7.21.6.6 The sprintf function
-    Synopsis
-1          #include <stdio.h>
-           int sprintf(char * restrict s,
-                const char * restrict format, ...);
-    Description
-2   The sprintf function is equivalent to fprintf, except that the output is written into
-    an array (specified by the argument s) rather than to a stream. A null character is written
-    at the end of the characters written; it is not counted as part of the returned value. If
-    copying takes place between objects that overlap, the behavior is undefined.
-    Returns
-3   The sprintf function returns the number of characters written in the array, not
-    counting the terminating null character, or a negative value if an encoding error occurred.
-
-[page 324] (Contents)
-
-    7.21.6.7 The sscanf function
-    Synopsis
-1           #include <stdio.h>
-            int sscanf(const char * restrict s,
-                 const char * restrict format, ...);
-    Description
-2   The sscanf function is equivalent to fscanf, except that input is obtained from a
-    string (specified by the argument s) rather than from a stream. Reaching the end of the
-    string is equivalent to encountering end-of-file for the fscanf function. If copying
-    takes place between objects that overlap, the behavior is undefined.
-    Returns
-3   The sscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the sscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.21.6.8 The vfprintf function
-    Synopsis
-1           #include <stdarg.h>
-            #include <stdio.h>
-            int vfprintf(FILE * restrict stream,
-                 const char * restrict format,
-                 va_list arg);
-    Description
-2   The vfprintf function is equivalent to fprintf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vfprintf function does not invoke the
-    va_end macro.277)
-    Returns
-3   The vfprintf function returns the number of characters transmitted, or a negative
-    value if an output or encoding error occurred.
-4   EXAMPLE       The following shows the use of the vfprintf function in a general error-reporting routine.
-
-
-
-
-    277) As the functions vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf, and
-         vsscanf invoke the va_arg macro, the value of arg after the return is indeterminate.
-
-[page 325] (Contents)
-
-           #include <stdarg.h>
-           #include <stdio.h>
-           void error(char *function_name, char *format, ...)
-           {
-                 va_list args;
-                  va_start(args, format);
-                  // print out name of function causing error
-                  fprintf(stderr, "ERROR in %s: ", function_name);
-                  // print out remainder of message
-                  vfprintf(stderr, format, args);
-                  va_end(args);
-           }
-
-    7.21.6.9 The vfscanf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <stdio.h>
-           int vfscanf(FILE * restrict stream,
-                const char * restrict format,
-                va_list arg);
-    Description
-2   The vfscanf function is equivalent to fscanf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vfscanf function does not invoke the
-    va_end macro.277)
-    Returns
-3   The vfscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the vfscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.21.6.10 The vprintf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <stdio.h>
-           int vprintf(const char * restrict format,
-                va_list arg);
-    Description
-2   The vprintf function is equivalent to printf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-
-[page 326] (Contents)
-
-    possibly subsequent va_arg calls). The vprintf function does not invoke the
-    va_end macro.277)
-    Returns
-3   The vprintf function returns the number of characters transmitted, or a negative value
-    if an output or encoding error occurred.
-    7.21.6.11 The vscanf function
-    Synopsis
-1           #include <stdarg.h>
-            #include <stdio.h>
-            int vscanf(const char * restrict format,
-                 va_list arg);
-    Description
-2   The vscanf function is equivalent to scanf, with the variable argument list replaced
-    by arg, which shall have been initialized by the va_start macro (and possibly
-    subsequent va_arg calls). The vscanf function does not invoke the va_end
-    macro.277)
-    Returns
-3   The vscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the vscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.21.6.12 The vsnprintf function
-    Synopsis
-1           #include <stdarg.h>
-            #include <stdio.h>
-            int vsnprintf(char * restrict s, size_t n,
-                 const char * restrict format,
-                 va_list arg);
-    Description
-2   The vsnprintf function is equivalent to snprintf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vsnprintf function does not invoke the
-    va_end macro.277) If copying takes place between objects that overlap, the behavior is
-    undefined.
-
-
-
-[page 327] (Contents)
-
-    Returns
-3   The vsnprintf function returns the number of characters that would have been written
-    had n been sufficiently large, not counting the terminating null character, or a negative
-    value if an encoding error occurred. Thus, the null-terminated output has been
-    completely written if and only if the returned value is nonnegative and less than n.
-    7.21.6.13 The vsprintf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <stdio.h>
-           int vsprintf(char * restrict s,
-                const char * restrict format,
-                va_list arg);
-    Description
-2   The vsprintf function is equivalent to sprintf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vsprintf function does not invoke the
-    va_end macro.277) If copying takes place between objects that overlap, the behavior is
-    undefined.
-    Returns
-3   The vsprintf function returns the number of characters written in the array, not
-    counting the terminating null character, or a negative value if an encoding error occurred.
-    7.21.6.14 The vsscanf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <stdio.h>
-           int vsscanf(const char * restrict s,
-                const char * restrict format,
-                va_list arg);
-    Description
-2   The vsscanf function is equivalent to sscanf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vsscanf function does not invoke the
-    va_end macro.277)
-    Returns
-3   The vsscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the vsscanf function
-[page 328] (Contents)
-
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.21.7 Character input/output functions
-    7.21.7.1 The fgetc function
-    Synopsis
-1           #include <stdio.h>
-            int fgetc(FILE *stream);
-    Description
-2   If the end-of-file indicator for the input stream pointed to by stream is not set and a
-    next character is present, the fgetc function obtains that character as an unsigned
-    char converted to an int and advances the associated file position indicator for the
-    stream (if defined).
-    Returns
-3   If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
-    of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
-    fgetc function returns the next character from the input stream pointed to by stream.
-    If a read error occurs, the error indicator for the stream is set and the fgetc function
-    returns EOF.278)
-    7.21.7.2 The fgets function
-    Synopsis
-1           #include <stdio.h>
-            char *fgets(char * restrict s, int n,
-                 FILE * restrict stream);
-    Description
-2   The fgets function reads at most one less than the number of characters specified by n
-    from the stream pointed to by stream into the array pointed to by s. No additional
-    characters are read after a new-line character (which is retained) or after end-of-file. A
-    null character is written immediately after the last character read into the array.
-    Returns
-3   The fgets function returns s if successful. If end-of-file is encountered and no
-    characters have been read into the array, the contents of the array remain unchanged and a
-    null pointer is returned. If a read error occurs during the operation, the array contents are
-    indeterminate and a null pointer is returned.
-
-    278) An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
-
-[page 329] (Contents)
-
-    7.21.7.3 The fputc function
-    Synopsis
-1          #include <stdio.h>
-           int fputc(int c, FILE *stream);
-    Description
-2   The fputc function writes the character specified by c (converted to an unsigned
-    char) to the output stream pointed to by stream, at the position indicated by the
-    associated file position indicator for the stream (if defined), and advances the indicator
-    appropriately. If the file cannot support positioning requests, or if the stream was opened
-    with append mode, the character is appended to the output stream.
-    Returns
-3   The fputc function returns the character written. If a write error occurs, the error
-    indicator for the stream is set and fputc returns EOF.
-    7.21.7.4 The fputs function
-    Synopsis
-1          #include <stdio.h>
-           int fputs(const char * restrict s,
-                FILE * restrict stream);
-    Description
-2   The fputs function writes the string pointed to by s to the stream pointed to by
-    stream. The terminating null character is not written.
-    Returns
-3   The fputs function returns EOF if a write error occurs; otherwise it returns a
-    nonnegative value.
-    7.21.7.5 The getc function
-    Synopsis
-1          #include <stdio.h>
-           int getc(FILE *stream);
-    Description
-2   The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
-    may evaluate stream more than once, so the argument should never be an expression
-    with side effects.
-
-
-
-
-[page 330] (Contents)
-
-    Returns
-3   The getc function returns the next character from the input stream pointed to by
-    stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
-    getc returns EOF. If a read error occurs, the error indicator for the stream is set and
-    getc returns EOF.
-    7.21.7.6 The getchar function
-    Synopsis
-1           #include <stdio.h>
-            int getchar(void);
-    Description
-2   The getchar function is equivalent to getc with the argument stdin.
-    Returns
-3   The getchar function returns the next character from the input stream pointed to by
-    stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
-    getchar returns EOF. If a read error occurs, the error indicator for the stream is set and
-    getchar returns EOF.
-    7.21.7.7 The putc function
-    Synopsis
-1           #include <stdio.h>
-            int putc(int c, FILE *stream);
-    Description
-2   The putc function is equivalent to fputc, except that if it is implemented as a macro, it
-    may evaluate stream more than once, so that argument should never be an expression
-    with side effects.
-    Returns
-3   The putc function returns the character written. If a write error occurs, the error
-    indicator for the stream is set and putc returns EOF.
-    7.21.7.8 The putchar function
-    Synopsis
-1           #include <stdio.h>
-            int putchar(int c);
-    Description
-2   The putchar function is equivalent to putc with the second argument stdout.
-
-
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-
-    Returns
-3   The putchar function returns the character written. If a write error occurs, the error
-    indicator for the stream is set and putchar returns EOF.
-    7.21.7.9 The puts function
-    Synopsis
-1          #include <stdio.h>
-           int puts(const char *s);
-    Description
-2   The puts function writes the string pointed to by s to the stream pointed to by stdout,
-    and appends a new-line character to the output. The terminating null character is not
-    written.
-    Returns
-3   The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative
-    value.
-    7.21.7.10 The ungetc function
-    Synopsis
-1          #include <stdio.h>
-           int ungetc(int c, FILE *stream);
-    Description
-2   The ungetc function pushes the character specified by c (converted to an unsigned
-    char) back onto the input stream pointed to by stream. Pushed-back characters will be
-    returned by subsequent reads on that stream in the reverse order of their pushing. A
-    successful intervening call (with the stream pointed to by stream) to a file positioning
-    function (fseek, fsetpos, or rewind) discards any pushed-back characters for the
-    stream. The external storage corresponding to the stream is unchanged.
-3   One character of pushback is guaranteed. If the ungetc function is called too many
-    times on the same stream without an intervening read or file positioning operation on that
-    stream, the operation may fail.
-4   If the value of c equals that of the macro EOF, the operation fails and the input stream is
-    unchanged.
-5   A successful call to the ungetc function clears the end-of-file indicator for the stream.
-    The value of the file position indicator for the stream after reading or discarding all
-    pushed-back characters shall be the same as it was before the characters were pushed
-    back. For a text stream, the value of its file position indicator after a successful call to the
-    ungetc function is unspecified until all pushed-back characters are read or discarded.
-
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-
-    For a binary stream, its file position indicator is decremented by each successful call to
-    the ungetc function; if its value was zero before a call, it is indeterminate after the
-    call.279)
-    Returns
-6   The ungetc function returns the character pushed back after conversion, or EOF if the
-    operation fails.
-    Forward references: file positioning functions (7.21.9).
-    7.21.8 Direct input/output functions
-    7.21.8.1 The fread function
-    Synopsis
-1            #include <stdio.h>
-             size_t fread(void * restrict ptr,
-                  size_t size, size_t nmemb,
-                  FILE * restrict stream);
-    Description
-2   The fread function reads, into the array pointed to by ptr, up to nmemb elements
-    whose size is specified by size, from the stream pointed to by stream. For each
-    object, size calls are made to the fgetc function and the results stored, in the order
-    read, in an array of unsigned char exactly overlaying the object. The file position
-    indicator for the stream (if defined) is advanced by the number of characters successfully
-    read. If an error occurs, the resulting value of the file position indicator for the stream is
-    indeterminate. If a partial element is read, its value is indeterminate.
-    Returns
-3   The fread function returns the number of elements successfully read, which may be
-    less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero,
-    fread returns zero and the contents of the array and the state of the stream remain
-    unchanged.
-
-
-
-
-    279) See ''future library directions'' (7.30.9).
-
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-
-    7.21.8.2 The fwrite function
-    Synopsis
-1          #include <stdio.h>
-           size_t fwrite(const void * restrict ptr,
-                size_t size, size_t nmemb,
-                FILE * restrict stream);
-    Description
-2   The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
-    whose size is specified by size, to the stream pointed to by stream. For each object,
-    size calls are made to the fputc function, taking the values (in order) from an array of
-    unsigned char exactly overlaying the object. The file position indicator for the
-    stream (if defined) is advanced by the number of characters successfully written. If an
-    error occurs, the resulting value of the file position indicator for the stream is
-    indeterminate.
-    Returns
-3   The fwrite function returns the number of elements successfully written, which will be
-    less than nmemb only if a write error is encountered. If size or nmemb is zero,
-    fwrite returns zero and the state of the stream remains unchanged.
-    7.21.9 File positioning functions
-    7.21.9.1 The fgetpos function
-    Synopsis
-1          #include <stdio.h>
-           int fgetpos(FILE * restrict stream,
-                fpos_t * restrict pos);
-    Description
-2   The fgetpos function stores the current values of the parse state (if any) and file
-    position indicator for the stream pointed to by stream in the object pointed to by pos.
-    The values stored contain unspecified information usable by the fsetpos function for
-    repositioning the stream to its position at the time of the call to the fgetpos function.
-    Returns
-3   If successful, the fgetpos function returns zero; on failure, the fgetpos function
-    returns nonzero and stores an implementation-defined positive value in errno.
-    Forward references: the fsetpos function (7.21.9.3).
-
-
-
-
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-
-    7.21.9.2 The fseek function
-    Synopsis
-1           #include <stdio.h>
-            int fseek(FILE *stream, long int offset, int whence);
-    Description
-2   The fseek function sets the file position indicator for the stream pointed to by stream.
-    If a read or write error occurs, the error indicator for the stream is set and fseek fails.
-3   For a binary stream, the new position, measured in characters from the beginning of the
-    file, is obtained by adding offset to the position specified by whence. The specified
-    position is the beginning of the file if whence is SEEK_SET, the current value of the file
-    position indicator if SEEK_CUR, or end-of-file if SEEK_END. A binary stream need not
-    meaningfully support fseek calls with a whence value of SEEK_END.
-4   For a text stream, either offset shall be zero, or offset shall be a value returned by
-    an earlier successful call to the ftell function on a stream associated with the same file
-    and whence shall be SEEK_SET.
-5   After determining the new position, a successful call to the fseek function undoes any
-    effects of the ungetc function on the stream, clears the end-of-file indicator for the
-    stream, and then establishes the new position. After a successful fseek call, the next
-    operation on an update stream may be either input or output.
-    Returns
-6   The fseek function returns nonzero only for a request that cannot be satisfied.
-    Forward references: the ftell function (7.21.9.4).
-    7.21.9.3 The fsetpos function
-    Synopsis
-1           #include <stdio.h>
-            int fsetpos(FILE *stream, const fpos_t *pos);
-    Description
-2   The fsetpos function sets the mbstate_t object (if any) and file position indicator
-    for the stream pointed to by stream according to the value of the object pointed to by
-    pos, which shall be a value obtained from an earlier successful call to the fgetpos
-    function on a stream associated with the same file. If a read or write error occurs, the
-    error indicator for the stream is set and fsetpos fails.
-3   A successful call to the fsetpos function undoes any effects of the ungetc function
-    on the stream, clears the end-of-file indicator for the stream, and then establishes the new
-    parse state and position. After a successful fsetpos call, the next operation on an
-
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-
-    update stream may be either input or output.
-    Returns
-4   If successful, the fsetpos function returns zero; on failure, the fsetpos function
-    returns nonzero and stores an implementation-defined positive value in errno.
-    7.21.9.4 The ftell function
-    Synopsis
-1          #include <stdio.h>
-           long int ftell(FILE *stream);
-    Description
-2   The ftell function obtains the current value of the file position indicator for the stream
-    pointed to by stream. For a binary stream, the value is the number of characters from
-    the beginning of the file. For a text stream, its file position indicator contains unspecified
-    information, usable by the fseek function for returning the file position indicator for the
-    stream to its position at the time of the ftell call; the difference between two such
-    return values is not necessarily a meaningful measure of the number of characters written
-    or read.
-    Returns
-3   If successful, the ftell function returns the current value of the file position indicator
-    for the stream. On failure, the ftell function returns -1L and stores an
-    implementation-defined positive value in errno.
-    7.21.9.5 The rewind function
-    Synopsis
-1          #include <stdio.h>
-           void rewind(FILE *stream);
-    Description
-2   The rewind function sets the file position indicator for the stream pointed to by
-    stream to the beginning of the file. It is equivalent to
-           (void)fseek(stream, 0L, SEEK_SET)
-    except that the error indicator for the stream is also cleared.
-    Returns
-3   The rewind function returns no value.
-
-
-
-
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-
-    7.21.10 Error-handling functions
-    7.21.10.1 The clearerr function
-    Synopsis
-1           #include <stdio.h>
-            void clearerr(FILE *stream);
-    Description
-2   The clearerr function clears the end-of-file and error indicators for the stream pointed
-    to by stream.
-    Returns
-3   The clearerr function returns no value.
-    7.21.10.2 The feof function
-    Synopsis
-1           #include <stdio.h>
-            int feof(FILE *stream);
-    Description
-2   The feof function tests the end-of-file indicator for the stream pointed to by stream.
-    Returns
-3   The feof function returns nonzero if and only if the end-of-file indicator is set for
-    stream.
-    7.21.10.3 The ferror function
-    Synopsis
-1           #include <stdio.h>
-            int ferror(FILE *stream);
-    Description
-2   The ferror function tests the error indicator for the stream pointed to by stream.
-    Returns
-3   The ferror function returns nonzero if and only if the error indicator is set for
-    stream.
-
-
-
-
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-
-    7.21.10.4 The perror function
-    Synopsis
-1          #include <stdio.h>
-           void perror(const char *s);
-    Description
-2   The perror function maps the error number in the integer expression errno to an
-    error message. It writes a sequence of characters to the standard error stream thus: first
-    (if s is not a null pointer and the character pointed to by s is not the null character), the
-    string pointed to by s followed by a colon (:) and a space; then an appropriate error
-    message string followed by a new-line character. The contents of the error message
-    strings are the same as those returned by the strerror function with argument errno.
-    Returns
-3   The perror function returns no value.
-    Forward references: the strerror function (7.23.6.2).
-
-
-
-
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-
-    7.22 General utilities <stdlib.h>
-1   The header <stdlib.h> declares five types and several functions of general utility, and
-    defines several macros.280)
-2   The types declared are size_t and wchar_t (both described in 7.19),
-             div_t
-    which is a structure type that is the type of the value returned by the div function,
-             ldiv_t
-    which is a structure type that is the type of the value returned by the ldiv function, and
-             lldiv_t
-    which is a structure type that is the type of the value returned by the lldiv function.
-3   The macros defined are NULL (described in 7.19);
-             EXIT_FAILURE
-    and
-             EXIT_SUCCESS
-    which expand to integer constant expressions that can be used as the argument to the
-    exit function to return unsuccessful or successful termination status, respectively, to the
-    host environment;
-             RAND_MAX
-    which expands to an integer constant expression that is the maximum value returned by
-    the rand function; and
-             MB_CUR_MAX
-    which expands to a positive integer expression with type size_t that is the maximum
-    number of bytes in a multibyte character for the extended character set specified by the
-    current locale (category LC_CTYPE), which is never greater than MB_LEN_MAX.
-
-
-
-
-    280) See ''future library directions'' (7.30.10).
-
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-
-    7.22.1 Numeric conversion functions
-1   The functions atof, atoi, atol, and atoll need not affect the value of the integer
-    expression errno on an error. If the value of the result cannot be represented, the
-    behavior is undefined.
-    7.22.1.1 The atof function
-    Synopsis
-1          #include <stdlib.h>
-           double atof(const char *nptr);
-    Description
-2   The atof function converts the initial portion of the string pointed to by nptr to
-    double representation. Except for the behavior on error, it is equivalent to
-           strtod(nptr, (char **)NULL)
-    Returns
-3   The atof function returns the converted value.
-    Forward references: the strtod, strtof, and strtold functions (7.22.1.3).
-    7.22.1.2 The atoi, atol, and atoll functions
-    Synopsis
-1          #include <stdlib.h>
-           int atoi(const char *nptr);
-           long int atol(const char *nptr);
-           long long int atoll(const char *nptr);
-    Description
-2   The atoi, atol, and atoll functions convert the initial portion of the string pointed
-    to by nptr to int, long int, and long long int representation, respectively.
-    Except for the behavior on error, they are equivalent to
-           atoi: (int)strtol(nptr, (char **)NULL, 10)
-           atol: strtol(nptr, (char **)NULL, 10)
-           atoll: strtoll(nptr, (char **)NULL, 10)
-    Returns
-3   The atoi, atol, and atoll functions return the converted value.
-    Forward references: the strtol, strtoll, strtoul, and strtoull functions
-    (7.22.1.4).
-
-
-
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-
-    7.22.1.3 The strtod, strtof, and strtold functions
-    Synopsis
-1           #include <stdlib.h>
-            double strtod(const char * restrict nptr,
-                 char ** restrict endptr);
-            float strtof(const char * restrict nptr,
-                 char ** restrict endptr);
-            long double strtold(const char * restrict nptr,
-                 char ** restrict endptr);
-    Description
-2   The strtod, strtof, and strtold functions convert the initial portion of the string
-    pointed to by nptr to double, float, and long double representation,
-    respectively. First, they decompose the input string into three parts: an initial, possibly
-    empty, sequence of white-space characters (as specified by the isspace function), a
-    subject sequence resembling a floating-point constant or representing an infinity or NaN;
-    and a final string of one or more unrecognized characters, including the terminating null
-    character of the input string. Then, they attempt to convert the subject sequence to a
-    floating-point number, and return the result.
-3   The expected form of the subject sequence is an optional plus or minus sign, then one of
-    the following:
-    -- a nonempty sequence of decimal digits optionally containing a decimal-point
-      character, then an optional exponent part as defined in 6.4.4.2;
-    -- a 0x or 0X, then a nonempty sequence of hexadecimal digits optionally containing a
-      decimal-point character, then an optional binary exponent part as defined in 6.4.4.2;
-    -- INF or INFINITY, ignoring case
-    -- NAN or NAN(n-char-sequenceopt), ignoring case in the NAN part, where:
-               n-char-sequence:
-                      digit
-                      nondigit
-                      n-char-sequence digit
-                      n-char-sequence nondigit
-    The subject sequence is defined as the longest initial subsequence of the input string,
-    starting with the first non-white-space character, that is of the expected form. The subject
-    sequence contains no characters if the input string is not of the expected form.
-4   If the subject sequence has the expected form for a floating-point number, the sequence of
-    characters starting with the first digit or the decimal-point character (whichever occurs
-    first) is interpreted as a floating constant according to the rules of 6.4.4.2, except that the
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-
-    decimal-point character is used in place of a period, and that if neither an exponent part
-    nor a decimal-point character appears in a decimal floating point number, or if a binary
-    exponent part does not appear in a hexadecimal floating point number, an exponent part
-    of the appropriate type with value zero is assumed to follow the last digit in the string. If
-    the subject sequence begins with a minus sign, the sequence is interpreted as negated.281)
-    A character sequence INF or INFINITY is interpreted as an infinity, if representable in
-    the return type, else like a floating constant that is too large for the range of the return
-    type. A character sequence NAN or NAN(n-char-sequenceopt), is interpreted as a quiet
-    NaN, if supported in the return type, else like a subject sequence part that does not have
-    the expected form; the meaning of the n-char sequences is implementation-defined.282) A
-    pointer to the final string is stored in the object pointed to by endptr, provided that
-    endptr is not a null pointer.
-5   If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
-    value resulting from the conversion is correctly rounded.
-6   In other than the "C" locale, additional locale-specific subject sequence forms may be
-    accepted.
-7   If the subject sequence is empty or does not have the expected form, no conversion is
-    performed; the value of nptr is stored in the object pointed to by endptr, provided
-    that endptr is not a null pointer.
-    Recommended practice
-8   If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
-    the result is not exactly representable, the result should be one of the two numbers in the
-    appropriate internal format that are adjacent to the hexadecimal floating source value,
-    with the extra stipulation that the error should have a correct sign for the current rounding
-    direction.
-9   If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in
-    <float.h>) significant digits, the result should be correctly rounded. If the subject
-    sequence D has the decimal form and more than DECIMAL_DIG significant digits,
-    consider the two bounding, adjacent decimal strings L and U, both having
-    DECIMAL_DIG significant digits, such that the values of L, D, and U satisfy L <= D <= U.
-    The result should be one of the (equal or adjacent) values that would be obtained by
-    correctly rounding L and U according to the current rounding direction, with the extra
-
-    281) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
-         negating the value resulting from converting the corresponding unsigned sequence (see F.5); the two
-         methods may yield different results if rounding is toward positive or negative infinity. In either case,
-         the functions honor the sign of zero if floating-point arithmetic supports signed zeros.
-    282) An implementation may use the n-char sequence to determine extra information to be represented in
-         the NaN's significand.
-
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-
-     stipulation that the error with respect to D should have a correct sign for the current
-     rounding direction.283)
-     Returns
-10   The functions return the converted value, if any. If no conversion could be performed,
-     zero is returned. If the correct value overflows and default rounding is in effect (7.12.1),
-     plus or minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the
-     return type and sign of the value), and the value of the macro ERANGE is stored in
-     errno. If the result underflows (7.12.1), the functions return a value whose magnitude is
-     no greater than the smallest normalized positive number in the return type; whether
-     errno acquires the value ERANGE is implementation-defined.
-     7.22.1.4 The strtol, strtoll, strtoul, and strtoull functions
-     Synopsis
-1            #include <stdlib.h>
-             long int strtol(
-                  const char * restrict nptr,
-                  char ** restrict endptr,
-                  int base);
-             long long int strtoll(
-                  const char * restrict nptr,
-                  char ** restrict endptr,
-                  int base);
-             unsigned long int strtoul(
-                  const char * restrict nptr,
-                  char ** restrict endptr,
-                  int base);
-             unsigned long long int strtoull(
-                  const char * restrict nptr,
-                  char ** restrict endptr,
-                  int base);
-     Description
-2    The strtol, strtoll, strtoul, and strtoull functions convert the initial
-     portion of the string pointed to by nptr to long int, long long int, unsigned
-     long int, and unsigned long long int representation, respectively. First,
-     they decompose the input string into three parts: an initial, possibly empty, sequence of
-     white-space characters (as specified by the isspace function), a subject sequence
-
-
-     283) DECIMAL_DIG, defined in <float.h>, should be sufficiently large that L and U will usually round
-          to the same internal floating value, but if not will round to adjacent values.
-
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-
-    resembling an integer represented in some radix determined by the value of base, and a
-    final string of one or more unrecognized characters, including the terminating null
-    character of the input string. Then, they attempt to convert the subject sequence to an
-    integer, and return the result.
-3   If the value of base is zero, the expected form of the subject sequence is that of an
-    integer constant as described in 6.4.4.1, optionally preceded by a plus or minus sign, but
-    not including an integer suffix. If the value of base is between 2 and 36 (inclusive), the
-    expected form of the subject sequence is a sequence of letters and digits representing an
-    integer with the radix specified by base, optionally preceded by a plus or minus sign,
-    but not including an integer suffix. The letters from a (or A) through z (or Z) are
-    ascribed the values 10 through 35; only letters and digits whose ascribed values are less
-    than that of base are permitted. If the value of base is 16, the characters 0x or 0X may
-    optionally precede the sequence of letters and digits, following the sign if present.
-4   The subject sequence is defined as the longest initial subsequence of the input string,
-    starting with the first non-white-space character, that is of the expected form. The subject
-    sequence contains no characters if the input string is empty or consists entirely of white
-    space, or if the first non-white-space character is other than a sign or a permissible letter
-    or digit.
-5   If the subject sequence has the expected form and the value of base is zero, the sequence
-    of characters starting with the first digit is interpreted as an integer constant according to
-    the rules of 6.4.4.1. If the subject sequence has the expected form and the value of base
-    is between 2 and 36, it is used as the base for conversion, ascribing to each letter its value
-    as given above. If the subject sequence begins with a minus sign, the value resulting from
-    the conversion is negated (in the return type). A pointer to the final string is stored in the
-    object pointed to by endptr, provided that endptr is not a null pointer.
-6   In other than the "C" locale, additional locale-specific subject sequence forms may be
-    accepted.
-7   If the subject sequence is empty or does not have the expected form, no conversion is
-    performed; the value of nptr is stored in the object pointed to by endptr, provided
-    that endptr is not a null pointer.
-    Returns
-8   The strtol, strtoll, strtoul, and strtoull functions return the converted
-    value, if any. If no conversion could be performed, zero is returned. If the correct value
-    is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN,
-    LLONG_MAX, ULONG_MAX, or ULLONG_MAX is returned (according to the return type
-    and sign of the value, if any), and the value of the macro ERANGE is stored in errno.
-
-
-
-
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-
-    7.22.2 Pseudo-random sequence generation functions
-    7.22.2.1 The rand function
-    Synopsis
-1           #include <stdlib.h>
-            int rand(void);
-    Description
-2   The rand function computes a sequence of pseudo-random integers in the range 0 to
-    RAND_MAX.284)
-3   The rand function is not required to avoid data races. The implementation shall behave
-    as if no library function calls the rand function.
-    Returns
-4   The rand function returns a pseudo-random integer.
-    Environmental limits
-5   The value of the RAND_MAX macro shall be at least 32767.
-    7.22.2.2 The srand function
-    Synopsis
-1           #include <stdlib.h>
-            void srand(unsigned int seed);
-    Description
-2   The srand function uses the argument as a seed for a new sequence of pseudo-random
-    numbers to be returned by subsequent calls to rand. If srand is then called with the
-    same seed value, the sequence of pseudo-random numbers shall be repeated. If rand is
-    called before any calls to srand have been made, the same sequence shall be generated
-    as when srand is first called with a seed value of 1.
-3   The implementation shall behave as if no library function calls the srand function.
-    Returns
-4   The srand function returns no value.
-
-
-
-
-    284) There are no guarantees as to the quality of the random sequence produced and some implementations
-         are known to produce sequences with distressingly non-random low-order bits. Applications with
-         particular requirements should use a generator that is known to be sufficient for their needs.
-
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-
-5   EXAMPLE       The following functions define a portable implementation of rand and srand.
-           static unsigned long int next = 1;
-           int rand(void)   // RAND_MAX assumed to be 32767
-           {
-                 next = next * 1103515245 + 12345;
-                 return (unsigned int)(next/65536) % 32768;
-           }
-           void srand(unsigned int seed)
-           {
-                 next = seed;
-           }
-
-    7.22.3 Memory management functions
-1   The order and contiguity of storage allocated by successive calls to the
-    aligned_alloc, calloc, malloc, and realloc functions is unspecified. The
-    pointer returned if the allocation succeeds is suitably aligned so that it may be assigned to
-    a pointer to any type of object with a fundamental alignment requirement and then used
-    to access such an object or an array of such objects in the space allocated (until the space
-    is explicitly deallocated). The lifetime of an allocated object extends from the allocation
-    until the deallocation. Each such allocation shall yield a pointer to an object disjoint from
-    any other object. The pointer returned points to the start (lowest byte address) of the
-    allocated space. If the space cannot be allocated, a null pointer is returned. If the size of
-    the space requested is zero, the behavior is implementation-defined: either a null pointer
-    is returned, or the behavior is as if the size were some nonzero value, except that the
-    returned pointer shall not be used to access an object.
-    7.22.3.1 The aligned_alloc function
-    Synopsis
-1          #include <stdlib.h>
-           void *aligned_alloc(size_t alignment, size_t size);
-    Description
-2   The aligned_alloc function allocates space for an object whose alignment is
-    specified by alignment, whose size is specified by size, and whose value is
-    indeterminate. The value of alignment shall be a valid alignment supported by the
-    implementation and the value of size shall be an integral multiple of alignment.
-    Returns
-3   The aligned_alloc function returns either a null pointer or a pointer to the allocated
-    space.
-
-
-
-
-[page 346] (Contents)
-
-    7.22.3.2 The calloc function
-    Synopsis
-1           #include <stdlib.h>
-            void *calloc(size_t nmemb, size_t size);
-    Description
-2   The calloc function allocates space for an array of nmemb objects, each of whose size
-    is size. The space is initialized to all bits zero.285)
-    Returns
-3   The calloc function returns either a null pointer or a pointer to the allocated space.
-    7.22.3.3 The free function
-    Synopsis
-1           #include <stdlib.h>
-            void free(void *ptr);
-    Description
-2   The free function causes the space pointed to by ptr to be deallocated, that is, made
-    available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if
-    the argument does not match a pointer earlier returned by a memory management
-    function, or if the space has been deallocated by a call to free or realloc, the
-    behavior is undefined.
-    Returns
-3   The free function returns no value.
-    7.22.3.4 The malloc function
-    Synopsis
-1           #include <stdlib.h>
-            void *malloc(size_t size);
-    Description
-2   The malloc function allocates space for an object whose size is specified by size and
-    whose value is indeterminate.
-
-
-
-
-    285) Note that this need not be the same as the representation of floating-point zero or a null pointer
-         constant.
-
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-
-    Returns
-3   The malloc function returns either a null pointer or a pointer to the allocated space.
-    7.22.3.5 The realloc function
-    Synopsis
-1          #include <stdlib.h>
-           void *realloc(void *ptr, size_t size);
-    Description
-2   The realloc function deallocates the old object pointed to by ptr and returns a
-    pointer to a new object that has the size specified by size. The contents of the new
-    object shall be the same as that of the old object prior to deallocation, up to the lesser of
-    the new and old sizes. Any bytes in the new object beyond the size of the old object have
-    indeterminate values.
-3   If ptr is a null pointer, the realloc function behaves like the malloc function for the
-    specified size. Otherwise, if ptr does not match a pointer earlier returned by a memory
-    management function, or if the space has been deallocated by a call to the free or
-    realloc function, the behavior is undefined. If memory for the new object cannot be
-    allocated, the old object is not deallocated and its value is unchanged.
-    Returns
-4   The realloc function returns a pointer to the new object (which may have the same
-    value as a pointer to the old object), or a null pointer if the new object could not be
-    allocated.
-    7.22.4 Communication with the environment
-    7.22.4.1 The abort function
-    Synopsis
-1          #include <stdlib.h>
-           _Noreturn void abort(void);
-    Description
-2   The abort function causes abnormal program termination to occur, unless the signal
-    SIGABRT is being caught and the signal handler does not return. Whether open streams
-    with unwritten buffered data are flushed, open streams are closed, or temporary files are
-    removed is implementation-defined. An implementation-defined form of the status
-    unsuccessful termination is returned to the host environment by means of the function
-    call raise(SIGABRT).
-
-
-
-
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-
-    Returns
-3   The abort function does not return to its caller.
-    7.22.4.2 The atexit function
-    Synopsis
-1           #include <stdlib.h>
-            int atexit(void (*func)(void));
-    Description
-2   The atexit function registers the function pointed to by func, to be called without
-    arguments at normal program termination.286)
-    Environmental limits
-3   The implementation shall support the registration of at least 32 functions.
-    Returns
-4   The atexit function returns zero if the registration succeeds, nonzero if it fails.
-    Forward references: the at_quick_exit function (7.22.4.3), the exit function
-    (7.22.4.4).
-    7.22.4.3 The at_quick_exit function
-    Synopsis
-1           #include <stdlib.h>
-            int at_quick_exit(void (*func)(void));
-    Description
-2   The at_quick_exit function registers the function pointed to by func, to be called
-    without arguments should quick_exit be called.287)
-    Environmental limits
-3   The implementation shall support the registration of at least 32 functions.
-    Returns
-4   The at_quick_exit function returns zero if the registration succeeds, nonzero if it
-    fails.
-    Forward references: the quick_exit function (7.22.4.7).
-
-    286) The atexit function registrations are distinct from the at_quick_exit registrations, so
-         applications may need to call both registration functions with the same argument.
-    287) The at_quick_exit function registrations are distinct from the atexit registrations, so
-         applications may need to call both registration functions with the same argument.
-
-[page 349] (Contents)
-
-    7.22.4.4 The exit function
-    Synopsis
-1           #include <stdlib.h>
-            _Noreturn void exit(int status);
-    Description
-2   The exit function causes normal program termination to occur. No functions registered
-    by the at_quick_exit function are called. If a program calls the exit function
-    more than once, or calls the quick_exit function in addition to the exit function, the
-    behavior is undefined.
-3   First, all functions registered by the atexit function are called, in the reverse order of
-    their registration,288) except that a function is called after any previously registered
-    functions that had already been called at the time it was registered. If, during the call to
-    any such function, a call to the longjmp function is made that would terminate the call
-    to the registered function, the behavior is undefined.
-4   Next, all open streams with unwritten buffered data are flushed, all open streams are
-    closed, and all files created by the tmpfile function are removed.
-5   Finally, control is returned to the host environment. If the value of status is zero or
-    EXIT_SUCCESS, an implementation-defined form of the status successful termination is
-    returned. If the value of status is EXIT_FAILURE, an implementation-defined form
-    of the status unsuccessful termination is returned. Otherwise the status returned is
-    implementation-defined.
-    Returns
-6   The exit function cannot return to its caller.
-    7.22.4.5 The _Exit function
-    Synopsis
-1           #include <stdlib.h>
-            _Noreturn void _Exit(int status);
-    Description
-2   The _Exit function causes normal program termination to occur and control to be
-    returned to the host environment. No functions registered by the atexit function, the
-    at_quick_exit function, or signal handlers registered by the signal function are
-    called. The status returned to the host environment is determined in the same way as for
-
-
-    288) Each function is called as many times as it was registered, and in the correct order with respect to
-         other registered functions.
-
-[page 350] (Contents)
-
-    the exit function (7.22.4.4). Whether open streams with unwritten buffered data are
-    flushed, open streams are closed, or temporary files are removed is implementation-
-    defined.
-    Returns
-3   The _Exit function cannot return to its caller.
-    7.22.4.6 The getenv function
-    Synopsis
-1           #include <stdlib.h>
-            char *getenv(const char *name);
-    Description
-2   The getenv function searches an environment list, provided by the host environment,
-    for a string that matches the string pointed to by name. The set of environment names
-    and the method for altering the environment list are implementation-defined. The
-    getenv function need not avoid data races with other threads of execution that modify
-    the environment list.289)
-3   The implementation shall behave as if no library function calls the getenv function.
-    Returns
-4   The getenv function returns a pointer to a string associated with the matched list
-    member. The string pointed to shall not be modified by the program, but may be
-    overwritten by a subsequent call to the getenv function. If the specified name cannot
-    be found, a null pointer is returned.
-    7.22.4.7 The quick_exit function
-    Synopsis
-1           #include <stdlib.h>
-            _Noreturn void quick_exit(int status);
-    Description
-2   The quick_exit function causes normal program termination to occur. No functions
-    registered by the atexit function or signal handlers registered by the signal function
-    are called. If a program calls the quick_exit function more than once, or calls the
-    exit function in addition to the quick_exit function, the behavior is undefined.
-3   The quick_exit function first calls all functions registered by the at_quick_exit
-    function, in the reverse order of their registration,290) except that a function is called after
-
-
-    289) Many implementations provide non-standard functions that modify the environment list.
-
-[page 351] (Contents)
-
-    any previously registered functions that had already been called at the time it was
-    registered. If, during the call to any such function, a call to the longjmp function is
-    made that would terminate the call to the registered function, the behavior is undefined.
-4   Then control is returned to the host environment by means of the function call
-    _Exit(status).
-    Returns
-5   The quick_exit function cannot return to its caller.
-    7.22.4.8 The system function
-    Synopsis
-1           #include <stdlib.h>
-            int system(const char *string);
-    Description
-2   If string is a null pointer, the system function determines whether the host
-    environment has a command processor. If string is not a null pointer, the system
-    function passes the string pointed to by string to that command processor to be
-    executed in a manner which the implementation shall document; this might then cause the
-    program calling system to behave in a non-conforming manner or to terminate.
-    Returns
-3   If the argument is a null pointer, the system function returns nonzero only if a
-    command processor is available. If the argument is not a null pointer, and the system
-    function does return, it returns an implementation-defined value.
-    7.22.5 Searching and sorting utilities
-1   These utilities make use of a comparison function to search or sort arrays of unspecified
-    type. Where an argument declared as size_t nmemb specifies the length of the array
-    for a function, nmemb can have the value zero on a call to that function; the comparison
-    function is not called, a search finds no matching element, and sorting performs no
-    rearrangement. Pointer arguments on such a call shall still have valid values, as described
-    in 7.1.4.
-2   The implementation shall ensure that the second argument of the comparison function
-    (when called from bsearch), or both arguments (when called from qsort), are
-    pointers to elements of the array.291) The first argument when called from bsearch
-    shall equal key.
-
-
-
-    290) Each function is called as many times as it was registered, and in the correct order with respect to
-         other registered functions.
-
-[page 352] (Contents)
-
-3   The comparison function shall not alter the contents of the array. The implementation
-    may reorder elements of the array between calls to the comparison function, but shall not
-    alter the contents of any individual element.
-4   When the same objects (consisting of size bytes, irrespective of their current positions
-    in the array) are passed more than once to the comparison function, the results shall be
-    consistent with one another. That is, for qsort they shall define a total ordering on the
-    array, and for bsearch the same object shall always compare the same way with the
-    key.
-5   A sequence point occurs immediately before and immediately after each call to the
-    comparison function, and also between any call to the comparison function and any
-    movement of the objects passed as arguments to that call.
-    7.22.5.1 The bsearch function
-    Synopsis
-1            #include <stdlib.h>
-             void *bsearch(const void *key, const void *base,
-                  size_t nmemb, size_t size,
-                  int (*compar)(const void *, const void *));
-    Description
-2   The bsearch function searches an array of nmemb objects, the initial element of which
-    is pointed to by base, for an element that matches the object pointed to by key. The
-    size of each element of the array is specified by size.
-3   The comparison function pointed to by compar is called with two arguments that point
-    to the key object and to an array element, in that order. The function shall return an
-    integer less than, equal to, or greater than zero if the key object is considered,
-    respectively, to be less than, to match, or to be greater than the array element. The array
-    shall consist of: all the elements that compare less than, all the elements that compare
-    equal to, and all the elements that compare greater than the key object, in that order.292)
-    Returns
-4   The bsearch function returns a pointer to a matching element of the array, or a null
-    pointer if no match is found. If two elements compare as equal, which element is
-
-
-    291) That is, if the value passed is p, then the following expressions are always nonzero:
-                  ((char *)p - (char *)base) % size == 0
-                  (char *)p >= (char *)base
-                  (char *)p < (char *)base + nmemb * size
-
-    292) In practice, the entire array is sorted according to the comparison function.
-
-[page 353] (Contents)
-
-    matched is unspecified.
-    7.22.5.2 The qsort function
-    Synopsis
-1           #include <stdlib.h>
-            void qsort(void *base, size_t nmemb, size_t size,
-                 int (*compar)(const void *, const void *));
-    Description
-2   The qsort function sorts an array of nmemb objects, the initial element of which is
-    pointed to by base. The size of each object is specified by size.
-3   The contents of the array are sorted into ascending order according to a comparison
-    function pointed to by compar, which is called with two arguments that point to the
-    objects being compared. The function shall return an integer less than, equal to, or
-    greater than zero if the first argument is considered to be respectively less than, equal to,
-    or greater than the second.
-4   If two elements compare as equal, their order in the resulting sorted array is unspecified.
-    Returns
-5   The qsort function returns no value.
-    7.22.6 Integer arithmetic functions
-    7.22.6.1 The abs, labs and llabs functions
-    Synopsis
-1           #include <stdlib.h>
-            int abs(int j);
-            long int labs(long int j);
-            long long int llabs(long long int j);
-    Description
-2   The abs, labs, and llabs functions compute the absolute value of an integer j. If the
-    result cannot be represented, the behavior is undefined.293)
-    Returns
-3   The abs, labs, and llabs, functions return the absolute value.
-
-
-
-
-    293) The absolute value of the most negative number cannot be represented in two's complement.
-
-[page 354] (Contents)
-
-    7.22.6.2 The div, ldiv, and lldiv functions
-    Synopsis
-1           #include <stdlib.h>
-            div_t div(int numer, int denom);
-            ldiv_t ldiv(long int numer, long int denom);
-            lldiv_t lldiv(long long int numer, long long int denom);
-    Description
-2   The div, ldiv, and lldiv, functions compute numer / denom and numer %
-    denom in a single operation.
-    Returns
-3   The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and
-    lldiv_t, respectively, comprising both the quotient and the remainder. The structures
-    shall contain (in either order) the members quot (the quotient) and rem (the remainder),
-    each of which has the same type as the arguments numer and denom. If either part of
-    the result cannot be represented, the behavior is undefined.
-    7.22.7 Multibyte/wide character conversion functions
-1   The behavior of the multibyte character functions is affected by the LC_CTYPE category
-    of the current locale. For a state-dependent encoding, each function is placed into its
-    initial conversion state at program startup and can be returned to that state by a call for
-    which its character pointer argument, s, is a null pointer. Subsequent calls with s as
-    other than a null pointer cause the internal conversion state of the function to be altered as
-    necessary. A call with s as a null pointer causes these functions to return a nonzero value
-    if encodings have state dependency, and zero otherwise.294) Changing the LC_CTYPE
-    category causes the conversion state of these functions to be indeterminate.
-    7.22.7.1 The mblen function
-    Synopsis
-1           #include <stdlib.h>
-            int mblen(const char *s, size_t n);
-    Description
-2   If s is not a null pointer, the mblen function determines the number of bytes contained
-    in the multibyte character pointed to by s. Except that the conversion state of the
-    mbtowc function is not affected, it is equivalent to
-
-
-
-    294) If the locale employs special bytes to change the shift state, these bytes do not produce separate wide
-         character codes, but are grouped with an adjacent multibyte character.
-
-[page 355] (Contents)
-
-           mbtowc((wchar_t *)0, (const char *)0, 0);
-           mbtowc((wchar_t *)0, s, n);
-3   The implementation shall behave as if no library function calls the mblen function.
-    Returns
-4   If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte
-    character encodings, respectively, do or do not have state-dependent encodings. If s is
-    not a null pointer, the mblen function either returns 0 (if s points to the null character),
-    or returns the number of bytes that are contained in the multibyte character (if the next n
-    or fewer bytes form a valid multibyte character), or returns -1 (if they do not form a valid
-    multibyte character).
-    Forward references: the mbtowc function (7.22.7.2).
-    7.22.7.2 The mbtowc function
-    Synopsis
-1          #include <stdlib.h>
-           int mbtowc(wchar_t * restrict pwc,
-                const char * restrict s,
-                size_t n);
-    Description
-2   If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with
-    the byte pointed to by s to determine the number of bytes needed to complete the next
-    multibyte character (including any shift sequences). If the function determines that the
-    next multibyte character is complete and valid, it determines the value of the
-    corresponding wide character and then, if pwc is not a null pointer, stores that value in
-    the object pointed to by pwc. If the corresponding wide character is the null wide
-    character, the function is left in the initial conversion state.
-3   The implementation shall behave as if no library function calls the mbtowc function.
-    Returns
-4   If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte
-    character encodings, respectively, do or do not have state-dependent encodings. If s is
-    not a null pointer, the mbtowc function either returns 0 (if s points to the null character),
-    or returns the number of bytes that are contained in the converted multibyte character (if
-    the next n or fewer bytes form a valid multibyte character), or returns -1 (if they do not
-    form a valid multibyte character).
-5   In no case will the value returned be greater than n or the value of the MB_CUR_MAX
-    macro.
-
-
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-
-    7.22.7.3 The wctomb function
-    Synopsis
-1           #include <stdlib.h>
-            int wctomb(char *s, wchar_t wc);
-    Description
-2   The wctomb function determines the number of bytes needed to represent the multibyte
-    character corresponding to the wide character given by wc (including any shift
-    sequences), and stores the multibyte character representation in the array whose first
-    element is pointed to by s (if s is not a null pointer). At most MB_CUR_MAX characters
-    are stored. If wc is a null wide character, a null byte is stored, preceded by any shift
-    sequence needed to restore the initial shift state, and the function is left in the initial
-    conversion state.
-3   The implementation shall behave as if no library function calls the wctomb function.
-    Returns
-4   If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte
-    character encodings, respectively, do or do not have state-dependent encodings. If s is
-    not a null pointer, the wctomb function returns -1 if the value of wc does not correspond
-    to a valid multibyte character, or returns the number of bytes that are contained in the
-    multibyte character corresponding to the value of wc.
-5   In no case will the value returned be greater than the value of the MB_CUR_MAX macro.
-    7.22.8 Multibyte/wide string conversion functions
-1   The behavior of the multibyte string functions is affected by the LC_CTYPE category of
-    the current locale.
-    7.22.8.1 The mbstowcs function
-    Synopsis
-1           #include <stdlib.h>
-            size_t mbstowcs(wchar_t * restrict pwcs,
-                 const char * restrict s,
-                 size_t n);
-    Description
-2   The mbstowcs function converts a sequence of multibyte characters that begins in the
-    initial shift state from the array pointed to by s into a sequence of corresponding wide
-    characters and stores not more than n wide characters into the array pointed to by pwcs.
-    No multibyte characters that follow a null character (which is converted into a null wide
-    character) will be examined or converted. Each multibyte character is converted as if by
-    a call to the mbtowc function, except that the conversion state of the mbtowc function is
-[page 357] (Contents)
-
-    not affected.
-3   No more than n elements will be modified in the array pointed to by pwcs. If copying
-    takes place between objects that overlap, the behavior is undefined.
-    Returns
-4   If an invalid multibyte character is encountered, the mbstowcs function returns
-    (size_t)(-1). Otherwise, the mbstowcs function returns the number of array
-    elements modified, not including a terminating null wide character, if any.295)
-    7.22.8.2 The wcstombs function
-    Synopsis
-1            #include <stdlib.h>
-             size_t wcstombs(char * restrict s,
-                  const wchar_t * restrict pwcs,
-                  size_t n);
-    Description
-2   The wcstombs function converts a sequence of wide characters from the array pointed
-    to by pwcs into a sequence of corresponding multibyte characters that begins in the
-    initial shift state, and stores these multibyte characters into the array pointed to by s,
-    stopping if a multibyte character would exceed the limit of n total bytes or if a null
-    character is stored. Each wide character is converted as if by a call to the wctomb
-    function, except that the conversion state of the wctomb function is not affected.
-3   No more than n bytes will be modified in the array pointed to by s. If copying takes place
-    between objects that overlap, the behavior is undefined.
-    Returns
-4   If a wide character is encountered that does not correspond to a valid multibyte character,
-    the wcstombs function returns (size_t)(-1). Otherwise, the wcstombs function
-    returns the number of bytes modified, not including a terminating null character, if
-    any.295)
-
-
-
-
-    295) The array will not be null-terminated if the value returned is n.
-
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-
-    7.23 String handling <string.h>
-    7.23.1 String function conventions
-1   The header <string.h> declares one type and several functions, and defines one
-    macro useful for manipulating arrays of character type and other objects treated as arrays
-    of character type.296) The type is size_t and the macro is NULL (both described in
-    7.19). Various methods are used for determining the lengths of the arrays, but in all cases
-    a char * or void * argument points to the initial (lowest addressed) character of the
-    array. If an array is accessed beyond the end of an object, the behavior is undefined.
-2   Where an argument declared as size_t n specifies the length of the array for a
-    function, n can have the value zero on a call to that function. Unless explicitly stated
-    otherwise in the description of a particular function in this subclause, pointer arguments
-    on such a call shall still have valid values, as described in 7.1.4. On such a call, a
-    function that locates a character finds no occurrence, a function that compares two
-    character sequences returns zero, and a function that copies characters copies zero
-    characters.
-3   For all functions in this subclause, each character shall be interpreted as if it had the type
-    unsigned char (and therefore every possible object representation is valid and has a
-    different value).
-    7.23.2 Copying functions
-    7.23.2.1 The memcpy function
-    Synopsis
-1            #include <string.h>
-             void *memcpy(void * restrict s1,
-                  const void * restrict s2,
-                  size_t n);
-    Description
-2   The memcpy function copies n characters from the object pointed to by s2 into the
-    object pointed to by s1. If copying takes place between objects that overlap, the behavior
-    is undefined.
-    Returns
-3   The memcpy function returns the value of s1.
-
-
-
-
-    296) See ''future library directions'' (7.30.11).
-
-[page 359] (Contents)
-
-    7.23.2.2 The memmove function
-    Synopsis
-1          #include <string.h>
-           void *memmove(void *s1, const void *s2, size_t n);
-    Description
-2   The memmove function copies n characters from the object pointed to by s2 into the
-    object pointed to by s1. Copying takes place as if the n characters from the object
-    pointed to by s2 are first copied into a temporary array of n characters that does not
-    overlap the objects pointed to by s1 and s2, and then the n characters from the
-    temporary array are copied into the object pointed to by s1.
-    Returns
-3   The memmove function returns the value of s1.
-    7.23.2.3 The strcpy function
-    Synopsis
-1          #include <string.h>
-           char *strcpy(char * restrict s1,
-                const char * restrict s2);
-    Description
-2   The strcpy function copies the string pointed to by s2 (including the terminating null
-    character) into the array pointed to by s1. If copying takes place between objects that
-    overlap, the behavior is undefined.
-    Returns
-3   The strcpy function returns the value of s1.
-    7.23.2.4 The strncpy function
-    Synopsis
-1          #include <string.h>
-           char *strncpy(char * restrict s1,
-                const char * restrict s2,
-                size_t n);
-    Description
-2   The strncpy function copies not more than n characters (characters that follow a null
-    character are not copied) from the array pointed to by s2 to the array pointed to by
-
-
-
-
-[page 360] (Contents)
-
-    s1.297) If copying takes place between objects that overlap, the behavior is undefined.
-3   If the array pointed to by s2 is a string that is shorter than n characters, null characters
-    are appended to the copy in the array pointed to by s1, until n characters in all have been
-    written.
-    Returns
-4   The strncpy function returns the value of s1.
-    7.23.3 Concatenation functions
-    7.23.3.1 The strcat function
-    Synopsis
-1            #include <string.h>
-             char *strcat(char * restrict s1,
-                  const char * restrict s2);
-    Description
-2   The strcat function appends a copy of the string pointed to by s2 (including the
-    terminating null character) to the end of the string pointed to by s1. The initial character
-    of s2 overwrites the null character at the end of s1. If copying takes place between
-    objects that overlap, the behavior is undefined.
-    Returns
-3   The strcat function returns the value of s1.
-    7.23.3.2 The strncat function
-    Synopsis
-1            #include <string.h>
-             char *strncat(char * restrict s1,
-                  const char * restrict s2,
-                  size_t n);
-    Description
-2   The strncat function appends not more than n characters (a null character and
-    characters that follow it are not appended) from the array pointed to by s2 to the end of
-    the string pointed to by s1. The initial character of s2 overwrites the null character at the
-    end of s1. A terminating null character is always appended to the result.298) If copying
-
-    297) Thus, if there is no null character in the first n characters of the array pointed to by s2, the result will
-         not be null-terminated.
-    298) Thus, the maximum number of characters that can end up in the array pointed to by s1 is
-         strlen(s1)+n+1.
-
-[page 361] (Contents)
-
-    takes place between objects that overlap, the behavior is undefined.
-    Returns
-3   The strncat function returns the value of s1.
-    Forward references: the strlen function (7.23.6.3).
-    7.23.4 Comparison functions
-1   The sign of a nonzero value returned by the comparison functions memcmp, strcmp,
-    and strncmp is determined by the sign of the difference between the values of the first
-    pair of characters (both interpreted as unsigned char) that differ in the objects being
-    compared.
-    7.23.4.1 The memcmp function
-    Synopsis
-1           #include <string.h>
-            int memcmp(const void *s1, const void *s2, size_t n);
-    Description
-2   The memcmp function compares the first n characters of the object pointed to by s1 to
-    the first n characters of the object pointed to by s2.299)
-    Returns
-3   The memcmp function returns an integer greater than, equal to, or less than zero,
-    accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
-    pointed to by s2.
-    7.23.4.2 The strcmp function
-    Synopsis
-1           #include <string.h>
-            int strcmp(const char *s1, const char *s2);
-    Description
-2   The strcmp function compares the string pointed to by s1 to the string pointed to by
-    s2.
-    Returns
-3   The strcmp function returns an integer greater than, equal to, or less than zero,
-    accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
-
-    299) The contents of ''holes'' used as padding for purposes of alignment within structure objects are
-         indeterminate. Strings shorter than their allocated space and unions may also cause problems in
-         comparison.
-
-[page 362] (Contents)
-
-    pointed to by s2.
-    7.23.4.3 The strcoll function
-    Synopsis
-1           #include <string.h>
-            int strcoll(const char *s1, const char *s2);
-    Description
-2   The strcoll function compares the string pointed to by s1 to the string pointed to by
-    s2, both interpreted as appropriate to the LC_COLLATE category of the current locale.
-    Returns
-3   The strcoll function returns an integer greater than, equal to, or less than zero,
-    accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
-    pointed to by s2 when both are interpreted as appropriate to the current locale.
-    7.23.4.4 The strncmp function
-    Synopsis
-1           #include <string.h>
-            int strncmp(const char *s1, const char *s2, size_t n);
-    Description
-2   The strncmp function compares not more than n characters (characters that follow a
-    null character are not compared) from the array pointed to by s1 to the array pointed to
-    by s2.
-    Returns
-3   The strncmp function returns an integer greater than, equal to, or less than zero,
-    accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
-    to, or less than the possibly null-terminated array pointed to by s2.
-    7.23.4.5 The strxfrm function
-    Synopsis
-1           #include <string.h>
-            size_t strxfrm(char * restrict s1,
-                 const char * restrict s2,
-                 size_t n);
-    Description
-2   The strxfrm function transforms the string pointed to by s2 and places the resulting
-    string into the array pointed to by s1. The transformation is such that if the strcmp
-    function is applied to two transformed strings, it returns a value greater than, equal to, or
-
-[page 363] (Contents)
-
-    less than zero, corresponding to the result of the strcoll function applied to the same
-    two original strings. No more than n characters are placed into the resulting array
-    pointed to by s1, including the terminating null character. If n is zero, s1 is permitted to
-    be a null pointer. If copying takes place between objects that overlap, the behavior is
-    undefined.
-    Returns
-3   The strxfrm function returns the length of the transformed string (not including the
-    terminating null character). If the value returned is n or more, the contents of the array
-    pointed to by s1 are indeterminate.
-4   EXAMPLE The value of the following expression is the size of the array needed to hold the
-    transformation of the string pointed to by s.
-           1 + strxfrm(NULL, s, 0)
-
-    7.23.5 Search functions
-    7.23.5.1 The memchr function
-    Synopsis
-1          #include <string.h>
-           void *memchr(const void *s, int c, size_t n);
-    Description
-2   The memchr function locates the first occurrence of c (converted to an unsigned
-    char) in the initial n characters (each interpreted as unsigned char) of the object
-    pointed to by s.
-    Returns
-3   The memchr function returns a pointer to the located character, or a null pointer if the
-    character does not occur in the object.
-    7.23.5.2 The strchr function
-    Synopsis
-1          #include <string.h>
-           char *strchr(const char *s, int c);
-    Description
-2   The strchr function locates the first occurrence of c (converted to a char) in the
-    string pointed to by s. The terminating null character is considered to be part of the
-    string.
-    Returns
-3   The strchr function returns a pointer to the located character, or a null pointer if the
-    character does not occur in the string.
-[page 364] (Contents)
-
-    7.23.5.3 The strcspn function
-    Synopsis
-1           #include <string.h>
-            size_t strcspn(const char *s1, const char *s2);
-    Description
-2   The strcspn function computes the length of the maximum initial segment of the string
-    pointed to by s1 which consists entirely of characters not from the string pointed to by
-    s2.
-    Returns
-3   The strcspn function returns the length of the segment.
-    7.23.5.4 The strpbrk function
-    Synopsis
-1           #include <string.h>
-            char *strpbrk(const char *s1, const char *s2);
-    Description
-2   The strpbrk function locates the first occurrence in the string pointed to by s1 of any
-    character from the string pointed to by s2.
-    Returns
-3   The strpbrk function returns a pointer to the character, or a null pointer if no character
-    from s2 occurs in s1.
-    7.23.5.5 The strrchr function
-    Synopsis
-1           #include <string.h>
-            char *strrchr(const char *s, int c);
-    Description
-2   The strrchr function locates the last occurrence of c (converted to a char) in the
-    string pointed to by s. The terminating null character is considered to be part of the
-    string.
-    Returns
-3   The strrchr function returns a pointer to the character, or a null pointer if c does not
-    occur in the string.
-
-
-
-
-[page 365] (Contents)
-
-    7.23.5.6 The strspn function
-    Synopsis
-1          #include <string.h>
-           size_t strspn(const char *s1, const char *s2);
-    Description
-2   The strspn function computes the length of the maximum initial segment of the string
-    pointed to by s1 which consists entirely of characters from the string pointed to by s2.
-    Returns
-3   The strspn function returns the length of the segment.
-    7.23.5.7 The strstr function
-    Synopsis
-1          #include <string.h>
-           char *strstr(const char *s1, const char *s2);
-    Description
-2   The strstr function locates the first occurrence in the string pointed to by s1 of the
-    sequence of characters (excluding the terminating null character) in the string pointed to
-    by s2.
-    Returns
-3   The strstr function returns a pointer to the located string, or a null pointer if the string
-    is not found. If s2 points to a string with zero length, the function returns s1.
-    7.23.5.8 The strtok function
-    Synopsis
-1          #include <string.h>
-           char *strtok(char * restrict s1,
-                const char * restrict s2);
-    Description
-2   A sequence of calls to the strtok function breaks the string pointed to by s1 into a
-    sequence of tokens, each of which is delimited by a character from the string pointed to
-    by s2. The first call in the sequence has a non-null first argument; subsequent calls in the
-    sequence have a null first argument. The separator string pointed to by s2 may be
-    different from call to call.
-3   The first call in the sequence searches the string pointed to by s1 for the first character
-    that is not contained in the current separator string pointed to by s2. If no such character
-    is found, then there are no tokens in the string pointed to by s1 and the strtok function
-
-[page 366] (Contents)
-
-    returns a null pointer. If such a character is found, it is the start of the first token.
-4   The strtok function then searches from there for a character that is contained in the
-    current separator string. If no such character is found, the current token extends to the
-    end of the string pointed to by s1, and subsequent searches for a token will return a null
-    pointer. If such a character is found, it is overwritten by a null character, which
-    terminates the current token. The strtok function saves a pointer to the following
-    character, from which the next search for a token will start.
-5   Each subsequent call, with a null pointer as the value of the first argument, starts
-    searching from the saved pointer and behaves as described above.
-6   The strtok function is not required to avoid data races. The implementation shall
-    behave as if no library function calls the strtok function.
-    Returns
-7   The strtok function returns a pointer to the first character of a token, or a null pointer
-    if there is no token.
-8   EXAMPLE
-            #include <string.h>
-            static char str[] = "?a???b,,,#c";
-            char *t;
-            t   =   strtok(str, "?");       //   t   points to the token "a"
-            t   =   strtok(NULL, ",");      //   t   points to the token "??b"
-            t   =   strtok(NULL, "#,");     //   t   points to the token "c"
-            t   =   strtok(NULL, "?");      //   t   is a null pointer
-
-    7.23.6 Miscellaneous functions
-    7.23.6.1 The memset function
-    Synopsis
-1           #include <string.h>
-            void *memset(void *s, int c, size_t n);
-    Description
-2   The memset function copies the value of c (converted to an unsigned char) into
-    each of the first n characters of the object pointed to by s.
-    Returns
-3   The memset function returns the value of s.
-
-
-
-
-[page 367] (Contents)
-
-    7.23.6.2 The strerror function
-    Synopsis
-1          #include <string.h>
-           char *strerror(int errnum);
-    Description
-2   The strerror function maps the number in errnum to a message string. Typically,
-    the values for errnum come from errno, but strerror shall map any value of type
-    int to a message.
-3   The strerror function is not required to avoid data races. The implementation shall
-    behave as if no library function calls the strerror function.
-    Returns
-4   The strerror function returns a pointer to the string, the contents of which are locale-
-    specific. The array pointed to shall not be modified by the program, but may be
-    overwritten by a subsequent call to the strerror function.
-    7.23.6.3 The strlen function
-    Synopsis
-1          #include <string.h>
-           size_t strlen(const char *s);
-    Description
-2   The strlen function computes the length of the string pointed to by s.
-    Returns
-3   The strlen function returns the number of characters that precede the terminating null
-    character.
-
-
-
-
-[page 368] (Contents)
-
-    7.24 Type-generic math <tgmath.h>
-1   The header <tgmath.h> includes the headers <math.h> and <complex.h> and
-    defines several type-generic macros.
-2   Of the <math.h> and <complex.h> functions without an f (float) or l (long
-    double) suffix, several have one or more parameters whose corresponding real type is
-    double. For each such function, except modf, there is a corresponding type-generic
-    macro.300) The parameters whose corresponding real type is double in the function
-    synopsis are generic parameters. Use of the macro invokes a function whose
-    corresponding real type and type domain are determined by the arguments for the generic
-    parameters.301)
-3   Use of the macro invokes a function whose generic parameters have the corresponding
-    real type determined as follows:
-    -- First, if any argument for generic parameters has type long double, the type
-      determined is long double.
-    -- Otherwise, if any argument for generic parameters has type double or is of integer
-      type, the type determined is double.
-    -- Otherwise, the type determined is float.
-4   For each unsuffixed function in <math.h> for which there is a function in
-    <complex.h> with the same name except for a c prefix, the corresponding type-
-    generic macro (for both functions) has the same name as the function in <math.h>. The
-    corresponding type-generic macro for fabs and cabs is fabs.
-
-
-
-
-    300) Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to
-         make available the corresponding ordinary function.
-    301) If the type of the argument is not compatible with the type of the parameter for the selected function,
-         the behavior is undefined.
-
-[page 369] (Contents)
-
-            <math.h>          <complex.h>              type-generic
-             function            function                 macro
-              acos               cacos                   acos
-              asin               casin                   asin
-              atan               catan                   atan
-              acosh              cacosh                  acosh
-              asinh              casinh                  asinh
-              atanh              catanh                  atanh
-              cos                ccos                    cos
-              sin                csin                    sin
-              tan                ctan                    tan
-              cosh               ccosh                   cosh
-              sinh               csinh                   sinh
-              tanh               ctanh                   tanh
-              exp                cexp                    exp
-              log                clog                    log
-              pow                cpow                    pow
-              sqrt               csqrt                   sqrt
-              fabs               cabs                    fabs
-    If at least one argument for a generic parameter is complex, then use of the macro invokes
-    a complex function; otherwise, use of the macro invokes a real function.
-5   For each unsuffixed function in <math.h> without a c-prefixed counterpart in
-    <complex.h> (except modf), the corresponding type-generic macro has the same
-    name as the function. These type-generic macros are:
-          atan2                fma                  llround              remainder
-          cbrt                 fmax                 log10                remquo
-          ceil                 fmin                 log1p                rint
-          copysign             fmod                 log2                 round
-          erf                  frexp                logb                 scalbn
-          erfc                 hypot                lrint                scalbln
-          exp2                 ilogb                lround               tgamma
-          expm1                ldexp                nearbyint            trunc
-          fdim                 lgamma               nextafter
-          floor                llrint               nexttoward
-    If all arguments for generic parameters are real, then use of the macro invokes a real
-    function; otherwise, use of the macro results in undefined behavior.
-
-
-
-
-[page 370] (Contents)
-
-6   For each unsuffixed function in <complex.h> that is not a c-prefixed counterpart to a
-    function in <math.h>, the corresponding type-generic macro has the same name as the
-    function. These type-generic macros are:
-            carg                    conj                     creal
-            cimag                   cproj
-    Use of the macro with any real or complex argument invokes a complex function.
-7   EXAMPLE       With the declarations
-            #include <tgmath.h>
-            int n;
-            float f;
-            double d;
-            long double ld;
-            float complex fc;
-            double complex dc;
-            long double complex ldc;
-    functions invoked by use of type-generic macros are shown in the following table:
-                     macro use                                  invokes
-                exp(n)                              exp(n), the function
-                acosh(f)                            acoshf(f)
-                sin(d)                              sin(d), the function
-                atan(ld)                            atanl(ld)
-                log(fc)                             clogf(fc)
-                sqrt(dc)                            csqrt(dc)
-                pow(ldc, f)                         cpowl(ldc, f)
-                remainder(n, n)                     remainder(n, n), the function
-                nextafter(d, f)                     nextafter(d, f), the function
-                nexttoward(f, ld)                   nexttowardf(f, ld)
-                copysign(n, ld)                     copysignl(n, ld)
-                ceil(fc)                            undefined behavior
-                rint(dc)                            undefined behavior
-                fmax(ldc, ld)                       undefined behavior
-                carg(n)                             carg(n), the function
-                cproj(f)                            cprojf(f)
-                creal(d)                            creal(d), the function
-                cimag(ld)                           cimagl(ld)
-                fabs(fc)                            cabsf(fc)
-                carg(dc)                            carg(dc), the function
-                cproj(ldc)                          cprojl(ldc)
-
-
-
-
-[page 371] (Contents)
-
-    7.25 Threads <threads.h>
-    7.25.1 Introduction
-1   The header <threads.h> defines macros, and declares types, enumeration constants,
-    and functions that support multiple threads of execution.
-2   Implementations that define the macro __STDC_NO_THREADS__ need not provide
-    this header nor support any of its facilities.
-3   The macros are
-           ONCE_FLAG_INIT
-    which expands to a value that can be used to initialize an object of type once_flag;
-    and
-           TSS_DTOR_ITERATIONS
-    which expands to an integer constant expression representing the maximum number of
-    times that destructors will be called when a thread terminates.
-4   The types are
-           cnd_t
-    which is a complete object type that holds an identifier for a condition variable;
-           thrd_t
-    which is a complete object type that holds an identifier for a thread;
-           tss_t
-    which is a complete object type that holds an identifier for a thread-specific storage
-    pointer;
-           mtx_t
-    which is a complete object type that holds an identifier for a mutex;
-           tss_dtor_t
-    which is the function pointer type void (*)(void*), used for a destructor for a
-    thread-specific storage pointer;
-           thrd_start_t
-    which is the function pointer type int (*)(void*) that is passed to thrd_create
-    to create a new thread;
-           once_flag
-    which is a complete object type that holds a flag for use by call_once; and
-
-
-[page 372] (Contents)
-
-            xtime
-    which is a structure type that holds a time specified in seconds and nanoseconds. The
-    structure shall contain at least the following members, in any order.
-            time_t sec;
-            long nsec;
-5   The enumeration constants are
-            mtx_plain
-    which is passed to mtx_init to create a mutex object that supports neither timeout nor
-    test and return;
-            mtx_recursive
-    which is passed to mtx_init to create a mutex object that supports recursive locking;
-            mtx_timed
-    which is passed to mtx_init to create a mutex object that supports timeout;
-            mtx_try
-    which is passed to mtx_init to create a mutex object that supports test and return;
-            thrd_timeout
-    which is returned by a timed wait function to indicate that the time specified in the call
-    was reached without acquiring the requested resource;
-            thrd_success
-    which is returned by a function to indicate that the requested operation succeeded;
-            thrd_busy
-    which is returned by a function to indicate that the requested operation failed because a
-    resource requested by a test and return function is already in use;
-            thrd_error
-    which is returned by a function to indicate that the requested operation failed; and
-            thrd_nomem
-    which is returned by a function to indicate that the requested operation failed because it
-    was unable to allocate memory.
-
-
-
-
-[page 373] (Contents)
-
-    7.25.2 Initialization functions
-    7.25.2.1 The call_once function
-    Synopsis
-1          #include <threads.h>
-           void call_once(once_flag *flag, void (*func)(void));
-    Description
-2   The call_once function uses the once_flag pointed to by flag to ensure that
-    func is called exactly once, the first time the call_once function is called with that
-    value of flag. Completion of an effective call to the call_once function synchronizes
-    with all subsequent calls to the call_once function with the same value of flag.
-    Returns
-3   The call_once function returns no value.
-    7.25.3 Condition variable functions
-    7.25.3.1 The cnd_broadcast function
-    Synopsis
-1          #include <threads.h>
-           int cnd_broadcast(cnd_t *cond);
-    Description
-2   The cnd_broadcast function unblocks all of the threads that are blocked on the
-    condition variable pointed to by cond at the time of the call. If no threads are blocked
-    on the condition variable pointed to by cond at the time of the call, the function does
-    nothing.
-    Returns
-3   The cnd_broadcast function returns thrd_success on success, or thrd_error
-    if the request could not be honored.
-    7.25.3.2 The cnd_destroy function
-    Synopsis
-1          #include <threads.h>
-           void cnd_destroy(cnd_t *cond);
-    Description
-2   The cnd_destroy function releases all resources used by the condition variable
-    pointed to by cond. The cnd_destroy function requires that no threads be blocked
-    waiting for the condition variable pointed to by cond.
-
-[page 374] (Contents)
-
-    Returns
-3   The cnd_destroy function returns no value.
-    7.25.3.3 The cnd_init function
-    Synopsis
-1           #include <threads.h>
-            int cnd_init(cnd_t *cond);
-    Description
-2   The cnd_init function creates a condition variable. If it succeeds it sets the variable
-    pointed to by cond to a value that uniquely identifies the newly created condition
-    variable. A thread that calls cnd_wait on a newly created condition variable will
-    block.
-    Returns
-3   The cnd_init function returns thrd_success on success, or thrd_nomem if no
-    memory could be allocated for the newly created condition, or thrd_error if the
-    request could not be honored.
-    7.25.3.4 The cnd_signal function
-    Synopsis
-1           #include <threads.h>
-            int cnd_signal(cnd_t *cond);
-    Description
-2   The cnd_signal function unblocks one of the threads that are blocked on the
-    condition variable pointed to by cond at the time of the call. If no threads are blocked
-    on the condition variable at the time of the call, the function does nothing and return
-    success.
-    Returns
-3   The cnd_signal function returns thrd_success on success or thrd_error if
-    the request could not be honored.
-    7.25.3.5 The cnd_timedwait function
-    Synopsis
-1           #include <threads.h>
-            int cnd_timedwait(cnd_t *cond, mtx_t *mtx,
-                 const xtime *xt);
-
-
-
-
-[page 375] (Contents)
-
-    Description
-2   The cnd_timedwait function atomically unlocks the mutex pointed to by mtx and
-    endeavors to block until the condition variable pointed to by cond is signaled by a call to
-    cnd_signal or to cnd_broadcast, or until after the time specified by the xtime
-    object pointed to by xt. When the calling thread becomes unblocked it locks the variable
-    pointed to by mtx before it returns. The cnd_timedwait function requires that the
-    mutex pointed to by mtx be locked by the calling thread.
-    Returns
-3   The cnd_timedwait function returns thrd_success upon success, or
-    thrd_timeout if the time specified in the call was reached without acquiring the
-    requested resource, or thrd_error if the request could not be honored.
-    7.25.3.6 The cnd_wait function
-    Synopsis
-1          #include <threads.h>
-           int cnd_wait(cnd_t *cond, mtx_t *mtx);
-    Description
-2   The cnd_wait function atomically unlocks the mutex pointed to by mtx and endeavors
-    to block until the condition variable pointed to by cond is signaled by a call to
-    cnd_signal or to cnd_broadcast. When the calling thread becomes unblocked it
-    locks the mutex pointed to by mtx before it returns. If the mutex pointed to by mtx is
-    not locked by the calling thread, the cnd_wait function will act as if the abort
-    function is called.
-    Returns
-3   The cnd_wait function returns thrd_success on success or thrd_error if the
-    request could not be honored.
-    7.25.4 Mutex functions
-    7.25.4.1 The mtx_destroy function
-    Synopsis
-1          #include <threads.h>
-           void mtx_destroy(mtx_t *mtx);
-    Description
-2   The mtx_destroy function releases any resources used by the mutex pointed to by
-    mtx. No threads can be blocked waiting for the mutex pointed to by mtx.
-
-
-
-[page 376] (Contents)
-
-    Returns
-3   The mtx_destroy function returns no value.
-    7.25.4.2 The mtx_init function
-    Synopsis
-1           #include <threads.h>
-            int mtx_init(mtx_t *mtx, int type);
-    Description
-2   The mtx_init function creates a mutex object with properties indicated by type,
-    which must have one of the six values:
-    mtx_plain for a simple non-recursive mutex,
-    mtx_timed for a non-recursive mutex that supports timeout,
-    mtx_try      for a non-recursive mutex that supports test and return,
-    mtx_plain | mtx_recursive for a simple recursive mutex,
-    mtx_timed | mtx_recursive for a recursive mutex that supports timeout, or
-    mtx_try | mtx_recursive for a recursive mutex that supports test and return.
-3   If the mtx_init function succeeds, it sets the mutex pointed to by mtx to a value that
-    uniquely identifies the newly created mutex.
-    Returns
-4   The mtx_init function returns thrd_success on success, or thrd_error if the
-    request could not be honored.
-    7.25.4.3 The mtx_lock function
-    Synopsis
-1           #include <threads.h>
-            int mtx_lock(mtx_t *mtx);
-    Description
-2   The mtx_lock function blocks until it locks the mutex pointed to by mtx. If the mutex
-    is non-recursive, it shall not be locked by the calling thread. Prior calls to mtx_unlock
-    on the same mutex shall synchronize with this operation.
-    Returns
-3   The mtx_lock function returns thrd_success on success, or thrd_busy if the
-    resource requested is already in use, or thrd_error if the request could not be
-    honored.
-
-
-
-
-[page 377] (Contents)
-
-    7.25.4.4 The mtx_timedlock function
-    Synopsis
-1          #include <threads.h>
-           int mtx_timedlock(mtx_t *mtx, const xtime *xt);
-    Description
-2   The mtx_timedlock function endeavors to block until it locks the mutex pointed to by
-    mtx or until the time specified by the xtime object xt has passed. The specified mutex
-    shall support timeout. Prior calls to mtx_unlock on the same mutex shall synchronize
-    with this operation.                                                                 *
-    Returns
-3   The mtx_timedlock function returns thrd_success on success, or thrd_busy
-    if the resource requested is already in use, or thrd_timeout if the time specified was
-    reached without acquiring the requested resource, or thrd_error if the request could
-    not be honored.
-    7.25.4.5 The mtx_trylock function
-    Synopsis
-1          #include <threads.h>
-           int mtx_trylock(mtx_t *mtx);
-    Description
-2   The mtx_trylock function endeavors to lock the mutex pointed to by mtx. The
-    specified mutex shall support either test and return or timeout. If the mutex is already
-    locked, the function returns without blocking. Prior calls to mtx_unlock on the same
-    mutex shall synchronize with this operation.                                            *
-    Returns
-3   The mtx_trylock function returns thrd_success on success, or thrd_busy if
-    the resource requested is already in use, or thrd_error if the request could not be
-    honored.
-    7.25.4.6 The mtx_unlock function
-    Synopsis
-1          #include <threads.h>
-           int mtx_unlock(mtx_t *mtx);
-    Description
-2   The mtx_unlock function unlocks the mutex pointed to by mtx. The mutex pointed to
-    by mtx shall be locked by the calling thread.
-
-[page 378] (Contents)
-
-    Returns
-3   The mtx_unlock function returns thrd_success on success or thrd_error if
-    the request could not be honored.
-    7.25.5 Thread functions
-    7.25.5.1 The thrd_create function
-    Synopsis
-1           #include <threads.h>
-            int thrd_create(thrd_t *thr, thrd_start_t func,
-                 void *arg);
-    Description
-2   The thrd_create function creates a new thread executing func(arg). If the
-    thrd_create function succeeds, it sets the thread thr to a value that uniquely
-    identifies the newly created thread.
-    Returns
-3   The thrd_create function returns thrd_success on success, or thrd_nomem if
-    no memory could be allocated for the thread requested, or thrd_error if the request
-    could not be honored.
-    7.25.5.2 The thrd_current function
-    Synopsis
-1           #include <threads.h>
-            thrd_t thrd_current(void);
-    Description
-2   The thrd_current function identifies the thread that called it.
-    Returns
-3   The thrd_current function returns a value that uniquely identifies the thread that
-    called it.
-    7.25.5.3 The thrd_detach function
-    Synopsis
-1           #include <threads.h>
-            int thrd_detach(thrd_t thr);
-    Description
-2   The thrd_detach function tells the operating system to dispose of any resources
-    allocated to the thread identified by thr when that thread terminates. The value of the
-
-[page 379] (Contents)
-
-    thread identified by thr value shall not have been set by a call to thrd_join or
-    thrd_detach.
-    Returns
-3   The thrd_detach function returns thrd_success on success or thrd_error if
-    the request could not be honored.
-    7.25.5.4 The thrd_equal function
-    Synopsis
-1          #include <threads.h>
-           int thrd_equal(thrd_t thr0, thrd_t thr1);
-    Description
-2   The thrd_equal function will determine whether the thread identified by thr0 refers
-    to the thread identified by thr1.
-    Returns
-3   The thrd_equal function returns zero if the thread thr0 and the thread thr1 refer to
-    different threads. Otherwise the thrd_equal function returns a nonzero value.
-    7.25.5.5 The thrd_exit function
-    Synopsis
-1          #include <threads.h>
-           void thrd_exit(int res);
-    Description
-2   The thrd_exit function terminates execution of the calling thread and sets its result
-    code to res.
-    Returns
-3   The thrd_exit function returns no value.
-    7.25.5.6 The thrd_join function
-    Synopsis
-1          #include <threads.h>
-           int thrd_join(thrd_t thr, int *res);
-    Description
-2   The thrd_join function blocks until the thread identified by thr has terminated. If
-    the parameter res is not a null pointer, it stores the thread's result code in the integer
-    pointed to by res. The value of the thread identified by thr shall not have been set by a
-    call to thrd_join or thrd_detach.
-
-[page 380] (Contents)
-
-    Returns
-3   The thrd_join function returns thrd_success on success or thrd_error if the
-    request could not be honored.
-    7.25.5.7 The thrd_sleep function
-    Synopsis
-1           #include <threads.h>
-            void thrd_sleep(const xtime *xt);
-    Description
-2   The thrd_sleep function suspends execution of the calling thread until after the time
-    specified by the xtime object pointed to by xt.
-    Returns
-3   The thrd_sleep function returns no value.
-    7.25.5.8 The thrd_yield function
-    Synopsis
-1           #include <threads.h>
-            void thrd_yield(void);
-    Description
-2   The thrd_yield function endeavors to permit other threads to run, even if the current
-    thread would ordinarily continue to run.
-    Returns
-3   The thrd_yield function returns no value.
-    7.25.6 Thread-specific storage functions
-    7.25.6.1 The tss_create function
-    Synopsis
-1           #include <threads.h>
-            int tss_create(tss_t *key, tss_dtor_t dtor);
-    Description
-2   The tss_create function creates a thread-specific storage pointer with destructor
-    dtor, which may be null.
-    Returns
-3   If the tss_create function is successful, it sets the thread-specific storage pointed to
-    by key to a value that uniquely identifies the newly created pointer and returns
-    thrd_success; otherwise, thrd_error is returned and the thread-specific storage
-[page 381] (Contents)
-
-    pointed to by key is set to an undefined value.
-    7.25.6.2 The tss_delete function
-    Synopsis
-1          #include <threads.h>
-           void tss_delete(tss_t key);
-    Description
-2   The tss_delete function releases any resources used by the thread-specific storage
-    identified by key.
-    Returns
-3   The tss_delete function returns no value.
-    7.25.6.3 The tss_get function
-    Synopsis
-1          #include <threads.h>
-           void *tss_get(tss_t key);
-    Description
-2   The tss_get function returns the value for the current thread held in the thread-specific
-    storage identified by key.
-    Returns
-3   The tss_get function returns the value for the current thread if successful, or zero if
-    unsuccessful.
-    7.25.6.4 The tss_set function
-    Synopsis
-1          #include <threads.h>
-           int tss_set(tss_t key, void *val);
-    Description
-2   The tss_set function sets the value for the current thread held in the thread-specific
-    storage identified by key to val.
-    Returns
-3   The tss_set function returns thrd_success on success or thrd_error if the
-    request could not be honored.
-
-
-
-
-[page 382] (Contents)
-
-    7.25.7 Time functions
-    7.25.7.1 The xtime_get function
-    Synopsis
-1           #include <threads.h>
-            int xtime_get(xtime *xt, int base);
-    Description
-2   The xtime_get function sets the xtime object pointed to by xt to hold the current
-    time based on the time base base.
-    Returns
-3   If the xtime_get function is successful it returns the nonzero value base, which must
-    be TIME_UTC; otherwise, it returns zero.302)
-
-
-
-
-    302) Although an xtime object describes times with nanosecond resolution, the actual resolution in an
-         xtime object is system dependent.
-
-[page 383] (Contents)
-
-    7.26 Date and time <time.h>
-    7.26.1 Components of time
-1   The header <time.h> defines two macros, and declares several types and functions for
-    manipulating time. Many functions deal with a calendar time that represents the current
-    date (according to the Gregorian calendar) and time. Some functions deal with local
-    time, which is the calendar time expressed for some specific time zone, and with Daylight
-    Saving Time, which is a temporary change in the algorithm for determining local time.
-    The local time zone and Daylight Saving Time are implementation-defined.
-2   The macros defined are NULL (described in 7.19); and
-            CLOCKS_PER_SEC
-    which expands to an expression with type clock_t (described below) that is the
-    number per second of the value returned by the clock function.
-3   The types declared are size_t (described in 7.19);
-            clock_t
-    and
-            time_t
-    which are arithmetic types capable of representing times; and
-            struct tm
-    which holds the components of a calendar time, called the broken-down time.
-4   The range and precision of times representable in clock_t and time_t are
-    implementation-defined. The tm structure shall contain at least the following members,
-    in any order. The semantics of the members and their normal ranges are expressed in the
-    comments.303)
-            int    tm_sec;           //   seconds after the minute -- [0, 60]
-            int    tm_min;           //   minutes after the hour -- [0, 59]
-            int    tm_hour;          //   hours since midnight -- [0, 23]
-            int    tm_mday;          //   day of the month -- [1, 31]
-            int    tm_mon;           //   months since January -- [0, 11]
-            int    tm_year;          //   years since 1900
-            int    tm_wday;          //   days since Sunday -- [0, 6]
-            int    tm_yday;          //   days since January 1 -- [0, 365]
-            int    tm_isdst;         //   Daylight Saving Time flag
-
-
-
-    303) The range [0, 60] for tm_sec allows for a positive leap second.
-
-[page 384] (Contents)
-
-    The value of tm_isdst is positive if Daylight Saving Time is in effect, zero if Daylight
-    Saving Time is not in effect, and negative if the information is not available.
-    7.26.2 Time manipulation functions
-    7.26.2.1 The clock function
-    Synopsis
-1           #include <time.h>
-            clock_t clock(void);
-    Description
-2   The clock function determines the processor time used.
-    Returns
-3   The clock function returns the implementation's best approximation to the processor
-    time used by the program since the beginning of an implementation-defined era related
-    only to the program invocation. To determine the time in seconds, the value returned by
-    the clock function should be divided by the value of the macro CLOCKS_PER_SEC. If
-    the processor time used is not available or its value cannot be represented, the function
-    returns the value (clock_t)(-1).304)
-    7.26.2.2 The difftime function
-    Synopsis
-1           #include <time.h>
-            double difftime(time_t time1, time_t time0);
-    Description
-2   The difftime function computes the difference between two calendar times: time1 -
-    time0.
-    Returns
-3   The difftime function returns the difference expressed in seconds as a double.
-
-
-
-
-    304) In order to measure the time spent in a program, the clock function should be called at the start of
-         the program and its return value subtracted from the value returned by subsequent calls.
-
-[page 385] (Contents)
-
-    7.26.2.3 The mktime function
-    Synopsis
-1           #include <time.h>
-            time_t mktime(struct tm *timeptr);
-    Description
-2   The mktime function converts the broken-down time, expressed as local time, in the
-    structure pointed to by timeptr into a calendar time value with the same encoding as
-    that of the values returned by the time function. The original values of the tm_wday
-    and tm_yday components of the structure are ignored, and the original values of the
-    other components are not restricted to the ranges indicated above.305) On successful
-    completion, the values of the tm_wday and tm_yday components of the structure are
-    set appropriately, and the other components are set to represent the specified calendar
-    time, but with their values forced to the ranges indicated above; the final value of
-    tm_mday is not set until tm_mon and tm_year are determined.
-    Returns
-3   The mktime function returns the specified calendar time encoded as a value of type
-    time_t. If the calendar time cannot be represented, the function returns the value
-    (time_t)(-1).
-4   EXAMPLE       What day of the week is July 4, 2001?
-            #include <stdio.h>
-            #include <time.h>
-            static const char *const wday[] = {
-                    "Sunday", "Monday", "Tuesday", "Wednesday",
-                    "Thursday", "Friday", "Saturday", "-unknown-"
-            };
-            struct tm time_str;
-            /* ... */
-
-
-
-
-    305) Thus, a positive or zero value for tm_isdst causes the mktime function to presume initially that
-         Daylight Saving Time, respectively, is or is not in effect for the specified time. A negative value
-         causes it to attempt to determine whether Daylight Saving Time is in effect for the specified time.
-
-[page 386] (Contents)
-
-            time_str.tm_year   = 2001 - 1900;
-            time_str.tm_mon    = 7 - 1;
-            time_str.tm_mday   = 4;
-            time_str.tm_hour   = 0;
-            time_str.tm_min    = 0;
-            time_str.tm_sec    = 1;
-            time_str.tm_isdst = -1;
-            if (mktime(&time_str) == (time_t)(-1))
-                  time_str.tm_wday = 7;
-            printf("%s\n", wday[time_str.tm_wday]);
-
-    7.26.2.4 The time function
-    Synopsis
-1           #include <time.h>
-            time_t time(time_t *timer);
-    Description
-2   The time function determines the current calendar time. The encoding of the value is
-    unspecified.
-    Returns
-3   The time function returns the implementation's best approximation to the current
-    calendar time. The value (time_t)(-1) is returned if the calendar time is not
-    available. If timer is not a null pointer, the return value is also assigned to the object it
-    points to.
-    7.26.3 Time conversion functions
-1   Except for the strftime function, these functions each return a pointer to one of two
-    types of static objects: a broken-down time structure or an array of char. Execution of
-    any of the functions that return a pointer to one of these object types may overwrite the
-    information in any object of the same type pointed to by the value returned from any
-    previous call to any of them and the functions are not required to avoid data races. The
-    implementation shall behave as if no other library functions call these functions.
-    7.26.3.1 The asctime function
-    Synopsis
-1           #include <time.h>
-            char *asctime(const struct tm *timeptr);
-    Description
-2   The asctime function converts the broken-down time in the structure pointed to by
-    timeptr into a string in the form
-            Sun Sep 16 01:03:52 1973\n\0
-
-[page 387] (Contents)
-
-    using the equivalent of the following algorithm.
-    char *asctime(const struct tm *timeptr)
-    {
-         static const char wday_name[7][3] = {
-              "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
-         };
-         static const char mon_name[12][3] = {
-              "Jan", "Feb", "Mar", "Apr", "May", "Jun",
-              "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
-         };
-         static char result[26];
-            sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n",
-                 wday_name[timeptr->tm_wday],
-                 mon_name[timeptr->tm_mon],
-                 timeptr->tm_mday, timeptr->tm_hour,
-                 timeptr->tm_min, timeptr->tm_sec,
-                 1900 + timeptr->tm_year);
-            return result;
-    }
-3   If any of the fields of the broken-down time contain values that are outside their normal
-    ranges,306) the behavior of the asctime function is undefined. Likewise, if the
-    calculated year exceeds four digits or is less than the year 1000, the behavior is
-    undefined.
-    Returns
-4   The asctime function returns a pointer to the string.
-    7.26.3.2 The ctime function
-    Synopsis
-1           #include <time.h>
-            char *ctime(const time_t *timer);
-    Description
-2   The ctime function converts the calendar time pointed to by timer to local time in the
-    form of a string. It is equivalent to
-            asctime(localtime(timer))
-
-
-
-    306) See 7.26.1.
-
-[page 388] (Contents)
-
-    Returns
-3   The ctime function returns the pointer returned by the asctime function with that
-    broken-down time as argument.
-    Forward references: the localtime function (7.26.3.4).
-    7.26.3.3 The gmtime function
-    Synopsis
-1           #include <time.h>
-            struct tm *gmtime(const time_t *timer);
-    Description
-2   The gmtime function converts the calendar time pointed to by timer into a broken-
-    down time, expressed as UTC.
-    Returns
-3   The gmtime function returns a pointer to the broken-down time, or a null pointer if the
-    specified time cannot be converted to UTC.
-    7.26.3.4 The localtime function
-    Synopsis
-1           #include <time.h>
-            struct tm *localtime(const time_t *timer);
-    Description
-2   The localtime function converts the calendar time pointed to by timer into a
-    broken-down time, expressed as local time.
-    Returns
-3   The localtime function returns a pointer to the broken-down time, or a null pointer if
-    the specified time cannot be converted to local time.
-    7.26.3.5 The strftime function
-    Synopsis
-1           #include <time.h>
-            size_t strftime(char * restrict s,
-                 size_t maxsize,
-                 const char * restrict format,
-                 const struct tm * restrict timeptr);
-
-
-
-
-[page 389] (Contents)
-
-    Description
-2   The strftime function places characters into the array pointed to by s as controlled by
-    the string pointed to by format. The format shall be a multibyte character sequence,
-    beginning and ending in its initial shift state. The format string consists of zero or
-    more conversion specifiers and ordinary multibyte characters. A conversion specifier
-    consists of a % character, possibly followed by an E or O modifier character (described
-    below), followed by a character that determines the behavior of the conversion specifier.
-    All ordinary multibyte characters (including the terminating null character) are copied
-    unchanged into the array. If copying takes place between objects that overlap, the
-    behavior is undefined. No more than maxsize characters are placed into the array.
-3   Each conversion specifier is replaced by appropriate characters as described in the
-    following list. The appropriate characters are determined using the LC_TIME category
-    of the current locale and by the values of zero or more members of the broken-down time
-    structure pointed to by timeptr, as specified in brackets in the description. If any of
-    the specified values is outside the normal range, the characters stored are unspecified.
-    %a    is replaced by the locale's abbreviated weekday name. [tm_wday]
-    %A    is replaced by the locale's full weekday name. [tm_wday]
-    %b    is replaced by the locale's abbreviated month name. [tm_mon]
-    %B    is replaced by the locale's full month name. [tm_mon]
-    %c    is replaced by the locale's appropriate date and time representation. [all specified
-          in 7.26.1]
-    %C    is replaced by the year divided by 100 and truncated to an integer, as a decimal
-          number (00-99). [tm_year]
-    %d    is replaced by the day of the month as a decimal number (01-31). [tm_mday]
-    %D    is equivalent to ''%m/%d/%y''. [tm_mon, tm_mday, tm_year]
-    %e    is replaced by the day of the month as a decimal number (1-31); a single digit is
-          preceded by a space. [tm_mday]
-    %F    is equivalent to ''%Y-%m-%d'' (the ISO 8601 date format). [tm_year, tm_mon,
-          tm_mday]
-    %g    is replaced by the last 2 digits of the week-based year (see below) as a decimal
-          number (00-99). [tm_year, tm_wday, tm_yday]
-    %G    is replaced by the week-based year (see below) as a decimal number (e.g., 1997).
-          [tm_year, tm_wday, tm_yday]
-    %h    is equivalent to ''%b''. [tm_mon]
-    %H    is replaced by the hour (24-hour clock) as a decimal number (00-23). [tm_hour]
-    %I    is replaced by the hour (12-hour clock) as a decimal number (01-12). [tm_hour]
-    %j    is replaced by the day of the year as a decimal number (001-366). [tm_yday]
-    %m    is replaced by the month as a decimal number (01-12). [tm_mon]
-    %M    is replaced by the minute as a decimal number (00-59). [tm_min]
-    %n    is replaced by a new-line character.
-
-[page 390] (Contents)
-
-    %p   is replaced by the locale's equivalent of the AM/PM designations associated with a
-         12-hour clock. [tm_hour]
-    %r   is replaced by the locale's 12-hour clock time. [tm_hour, tm_min, tm_sec]
-    %R   is equivalent to ''%H:%M''. [tm_hour, tm_min]
-    %S   is replaced by the second as a decimal number (00-60). [tm_sec]
-    %t   is replaced by a horizontal-tab character.
-    %T   is equivalent to ''%H:%M:%S'' (the ISO 8601 time format). [tm_hour, tm_min,
-         tm_sec]
-    %u   is replaced by the ISO 8601 weekday as a decimal number (1-7), where Monday
-         is 1. [tm_wday]
-    %U   is replaced by the week number of the year (the first Sunday as the first day of week
-         1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]
-    %V   is replaced by the ISO 8601 week number (see below) as a decimal number
-         (01-53). [tm_year, tm_wday, tm_yday]
-    %w   is replaced by the weekday as a decimal number (0-6), where Sunday is 0.
-         [tm_wday]
-    %W   is replaced by the week number of the year (the first Monday as the first day of
-         week 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]
-    %x   is replaced by the locale's appropriate date representation. [all specified in 7.26.1]
-    %X   is replaced by the locale's appropriate time representation. [all specified in 7.26.1]
-    %y   is replaced by the last 2 digits of the year as a decimal number (00-99).
-         [tm_year]
-    %Y   is replaced by the year as a decimal number (e.g., 1997). [tm_year]
-    %z   is replaced by the offset from UTC in the ISO 8601 format ''-0430'' (meaning 4
-         hours 30 minutes behind UTC, west of Greenwich), or by no characters if no time
-         zone is determinable. [tm_isdst]
-    %Z   is replaced by the locale's time zone name or abbreviation, or by no characters if no
-         time zone is determinable. [tm_isdst]
-    %%   is replaced by %.
-4   Some conversion specifiers can be modified by the inclusion of an E or O modifier
-    character to indicate an alternative format or specification. If the alternative format or
-    specification does not exist for the current locale, the modifier is ignored.
-    %Ec is replaced by the locale's alternative date and time representation.
-    %EC is replaced by the name of the base year (period) in the locale's alternative
-        representation.
-    %Ex is replaced by the locale's alternative date representation.
-    %EX is replaced by the locale's alternative time representation.
-    %Ey is replaced by the offset from %EC (year only) in the locale's alternative
-        representation.
-    %EY is replaced by the locale's full alternative year representation.
-
-[page 391] (Contents)
-
-    %Od is replaced by the day of the month, using the locale's alternative numeric symbols
-        (filled as needed with leading zeros, or with leading spaces if there is no alternative
-        symbol for zero).
-    %Oe is replaced by the day of the month, using the locale's alternative numeric symbols
-        (filled as needed with leading spaces).
-    %OH is replaced by the hour (24-hour clock), using the locale's alternative numeric
-        symbols.
-    %OI is replaced by the hour (12-hour clock), using the locale's alternative numeric
-        symbols.
-    %Om is replaced by the month, using the locale's alternative numeric symbols.
-    %OM is replaced by the minutes, using the locale's alternative numeric symbols.
-    %OS is replaced by the seconds, using the locale's alternative numeric symbols.
-    %Ou is replaced by the ISO 8601 weekday as a number in the locale's alternative
-        representation, where Monday is 1.
-    %OU is replaced by the week number, using the locale's alternative numeric symbols.
-    %OV is replaced by the ISO 8601 week number, using the locale's alternative numeric
-        symbols.
-    %Ow is replaced by the weekday as a number, using the locale's alternative numeric
-        symbols.
-    %OW is replaced by the week number of the year, using the locale's alternative numeric
-        symbols.
-    %Oy is replaced by the last 2 digits of the year, using the locale's alternative numeric
-        symbols.
-5   %g, %G, and %V give values according to the ISO 8601 week-based year. In this system,
-    weeks begin on a Monday and week 1 of the year is the week that includes January 4th,
-    which is also the week that includes the first Thursday of the year, and is also the first
-    week that contains at least four days in the year. If the first Monday of January is the
-    2nd, 3rd, or 4th, the preceding days are part of the last week of the preceding year; thus,
-    for Saturday 2nd January 1999, %G is replaced by 1998 and %V is replaced by 53. If
-    December 29th, 30th, or 31st is a Monday, it and any following days are part of week 1 of
-    the following year. Thus, for Tuesday 30th December 1997, %G is replaced by 1998 and
-    %V is replaced by 01.
-6   If a conversion specifier is not one of the above, the behavior is undefined.
-7   In the "C" locale, the E and O modifiers are ignored and the replacement strings for the
-    following specifiers are:
-    %a    the first three characters of %A.
-    %A    one of ''Sunday'', ''Monday'', ... , ''Saturday''.
-    %b    the first three characters of %B.
-    %B    one of ''January'', ''February'', ... , ''December''.
-    %c    equivalent to ''%a %b %e %T %Y''.
-[page 392] (Contents)
-
-    %p    one of ''AM'' or ''PM''.
-    %r    equivalent to ''%I:%M:%S %p''.
-    %x    equivalent to ''%m/%d/%y''.
-    %X    equivalent to %T.
-    %Z    implementation-defined.
-    Returns
-8   If the total number of resulting characters including the terminating null character is not
-    more than maxsize, the strftime function returns the number of characters placed
-    into the array pointed to by s not including the terminating null character. Otherwise,
-    zero is returned and the contents of the array are indeterminate.
-
-
-
-
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-
-    7.27 Unicode utilities <uchar.h>
-1   The header <uchar.h> declares types and functions for manipulating Unicode
-    characters.
-2   The types declared are mbstate_t (described in 7.29.1) and size_t (described in
-    7.19);
-           char16_t
-    which is an unsigned integer type used for 16-bit characters and is the same type as
-    uint_least16_t (described in 7.20.1.2); and
-           char32_t
-    which is an unsigned integer type used for 32-bit characters and is the same type as
-    uint_least32_t (also described in 7.20.1.2).
-    7.27.1 Restartable multibyte/wide character conversion functions
-1   These functions have a parameter, ps, of type pointer to mbstate_t that points to an
-    object that can completely describe the current conversion state of the associated
-    multibyte character sequence, which the functions alter as necessary. If ps is a null
-    pointer, each function uses its own internal mbstate_t object instead, which is
-    initialized at program startup to the initial conversion state; the functions are not required
-    to avoid data races in this case. The implementation behaves as if no library function
-    calls these functions with a null pointer for ps.
-    7.27.1.1 The mbrtoc16 function
-    Synopsis
-1          #include <uchar.h>
-           size_t mbrtoc16(char16_t * restrict pc16,
-                const char * restrict s, size_t n,
-                mbstate_t * restrict ps);
-    Description
-2   If s is a null pointer, the mbrtoc16 function is equivalent to the call:
-                   mbrtoc16(NULL, "", 1, ps)
-    In this case, the values of the parameters pc16 and n are ignored.
-3   If s is not a null pointer, the mbrtoc16 function inspects at most n bytes beginning with
-    the byte pointed to by s to determine the number of bytes needed to complete the next
-    multibyte character (including any shift sequences). If the function determines that the
-    next multibyte character is complete and valid, it determines the values of the
-    corresponding wide characters and then, if pc16 is not a null pointer, stores the value of
-    the first (or only) such character in the object pointed to by pc16. Subsequent calls will
-[page 394] (Contents)
-
-    store successive wide characters without consuming any additional input until all the
-    characters have been stored. If the corresponding wide character is the null wide
-    character, the resulting state described is the initial conversion state.
-    Returns
-4   The mbrtoc16 function returns the first of the following that applies (given the current
-    conversion state):
-    0                     if the next n or fewer bytes complete the multibyte character that
-                          corresponds to the null wide character (which is the value stored).
-    between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte
-                       character (which is the value stored); the value returned is the number
-                       of bytes that complete the multibyte character.
-    (size_t)(-3) if the next character resulting from a previous call has been stored (no
-                 bytes from the input have been consumed by this call).
-    (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid)
-                 multibyte character, and all n bytes have been processed (no value is
-                 stored).307)
-    (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes
-                 do not contribute to a complete and valid multibyte character (no
-                 value is stored); the value of the macro EILSEQ is stored in errno,
-                 and the conversion state is unspecified.
-    7.27.1.2 The c16rtomb function
-    Synopsis
-1           #include <uchar.h>
-            size_t c16rtomb(char * restrict s, char16_t c16,
-                 mbstate_t * restrict ps);
-    Description
-2   If s is a null pointer, the c16rtomb function is equivalent to the call
-                    c16rtomb(buf, L'\0', ps)
-    where buf is an internal buffer.
-3   If s is not a null pointer, the c16rtomb function determines the number of bytes needed
-    to represent the multibyte character that corresponds to the wide character given by c16
-    (including any shift sequences), and stores the multibyte character representation in the
-
-    307) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a
-         sequence of redundant shift sequences (for implementations with state-dependent encodings).
-
-[page 395] (Contents)
-
-    array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If
-    c16 is a null wide character, a null byte is stored, preceded by any shift sequence needed
-    to restore the initial shift state; the resulting state described is the initial conversion state.
-    Returns
-4   The c16rtomb function returns the number of bytes stored in the array object (including
-    any shift sequences). When c16 is not a valid wide character, an encoding error occurs:
-    the function stores the value of the macro EILSEQ in errno and returns
-    (size_t)(-1); the conversion state is unspecified.
-    7.27.1.3 The mbrtoc32 function
-    Synopsis
-1           #include <uchar.h>
-            size_t mbrtoc32(char32_t * restrict pc32,
-                 const char * restrict s, size_t n,
-                 mbstate_t * restrict ps);
-    Description
-2   If s is a null pointer, the mbrtoc32 function is equivalent to the call:
-                    mbrtoc32(NULL, "", 1, ps)
-    In this case, the values of the parameters pc32 and n are ignored.
-3   If s is not a null pointer, the mbrtoc32 function inspects at most n bytes beginning with
-    the byte pointed to by s to determine the number of bytes needed to complete the next
-    multibyte character (including any shift sequences). If the function determines that the
-    next multibyte character is complete and valid, it determines the values of the
-    corresponding wide characters and then, if pc32 is not a null pointer, stores the value of
-    the first (or only) such character in the object pointed to by pc32. Subsequent calls will
-    store successive wide characters without consuming any additional input until all the
-    characters have been stored. If the corresponding wide character is the null wide
-    character, the resulting state described is the initial conversion state.
-    Returns
-4   The mbrtoc32 function returns the first of the following that applies (given the current
-    conversion state):
-    0                    if the next n or fewer bytes complete the multibyte character that
-                         corresponds to the null wide character (which is the value stored).
-    between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte
-                       character (which is the value stored); the value returned is the number
-                       of bytes that complete the multibyte character.
-
-
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-
-    (size_t)(-3) if the next character resulting from a previous call has been stored (no
-                 bytes from the input have been consumed by this call).
-    (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid)
-                 multibyte character, and all n bytes have been processed (no value is
-                 stored).308)
-    (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes
-                 do not contribute to a complete and valid multibyte character (no
-                 value is stored); the value of the macro EILSEQ is stored in errno,
-                 and the conversion state is unspecified.
-    7.27.1.4 The c32rtomb function
-    Synopsis
-1           #include <uchar.h>
-            size_t c32rtomb(char * restrict s, char32_t c32,
-                 mbstate_t * restrict ps);
-    Description
-2   If s is a null pointer, the c32rtomb function is equivalent to the call
-                    c32rtomb(buf, L'\0', ps)
-    where buf is an internal buffer.
-3   If s is not a null pointer, the c32rtomb function determines the number of bytes needed
-    to represent the multibyte character that corresponds to the wide character given by c32
-    (including any shift sequences), and stores the multibyte character representation in the
-    array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If
-    c32 is a null wide character, a null byte is stored, preceded by any shift sequence needed
-    to restore the initial shift state; the resulting state described is the initial conversion state.
-    Returns
-4   The c32rtomb function returns the number of bytes stored in the array object (including
-    any shift sequences). When c32 is not a valid wide character, an encoding error occurs:
-    the function stores the value of the macro EILSEQ in errno and returns
-    (size_t)(-1); the conversion state is unspecified.
-
-
-
-
-    308) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a
-         sequence of redundant shift sequences (for implementations with state-dependent encodings).
-
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-
-    7.28 Extended multibyte and wide character utilities <wchar.h>
-    7.28.1 Introduction
-1   The header <wchar.h> defines four macros, and declares four data types, one tag, and
-    many functions.309)
-2   The types declared are wchar_t and size_t (both described in 7.19);
-             mbstate_t
-    which is a complete object type other than an array type that can hold the conversion state
-    information necessary to convert between sequences of multibyte characters and wide
-    characters;
-             wint_t
-    which is an integer type unchanged by default argument promotions that can hold any
-    value corresponding to members of the extended character set, as well as at least one
-    value that does not correspond to any member of the extended character set (see WEOF
-    below);310) and
-             struct tm
-    which is declared as an incomplete structure type (the contents are described in 7.26.1).
-3   The macros defined are NULL (described in 7.19); WCHAR_MIN and WCHAR_MAX
-    (described in 7.20.3); and
-             WEOF
-    which expands to a constant expression of type wint_t whose value does not
-    correspond to any member of the extended character set.311) It is accepted (and returned)
-    by several functions in this subclause to indicate end-of-file, that is, no more input from a
-    stream. It is also used as a wide character value that does not correspond to any member
-    of the extended character set.
-4   The functions declared are grouped as follows:
-    -- Functions that perform input and output of wide characters, or multibyte characters,
-      or both;
-    -- Functions that provide wide string numeric conversion;
-    -- Functions that perform general wide string manipulation;
-
-
-    309) See ''future library directions'' (7.30.12).
-    310) wchar_t and wint_t can be the same integer type.
-    311) The value of the macro WEOF may differ from that of EOF and need not be negative.
-
-[page 398] (Contents)
-
-    -- Functions for wide string date and time conversion; and
-    -- Functions that provide extended capabilities for conversion between multibyte and
-      wide character sequences.
-5   Unless explicitly stated otherwise, if the execution of a function described in this
-    subclause causes copying to take place between objects that overlap, the behavior is
-    undefined.
-    7.28.2 Formatted wide character input/output functions
-1   The formatted wide character input/output functions shall behave as if there is a sequence
-    point after the actions associated with each specifier.312)
-    7.28.2.1 The fwprintf function
-    Synopsis
-1           #include <stdio.h>
-            #include <wchar.h>
-            int fwprintf(FILE * restrict stream,
-                 const wchar_t * restrict format, ...);
-    Description
-2   The fwprintf function writes output to the stream pointed to by stream, under
-    control of the wide string pointed to by format that specifies how subsequent arguments
-    are converted for output. If there are insufficient arguments for the format, the behavior
-    is undefined. If the format is exhausted while arguments remain, the excess arguments
-    are evaluated (as always) but are otherwise ignored. The fwprintf function returns
-    when the end of the format string is encountered.
-3   The format is composed of zero or more directives: ordinary wide characters (not %),
-    which are copied unchanged to the output stream; and conversion specifications, each of
-    which results in fetching zero or more subsequent arguments, converting them, if
-    applicable, according to the corresponding conversion specifier, and then writing the
-    result to the output stream.
-4   Each conversion specification is introduced by the wide character %. After the %, the
-    following appear in sequence:
-    -- Zero or more flags (in any order) that modify the meaning of the conversion
-      specification.
-    -- An optional minimum field width. If the converted value has fewer wide characters
-      than the field width, it is padded with spaces (by default) on the left (or right, if the
-
-
-    312) The fwprintf functions perform writes to memory for the %n specifier.
-
-[page 399] (Contents)
-
-        left adjustment flag, described later, has been given) to the field width. The field
-        width takes the form of an asterisk * (described later) or a nonnegative decimal
-        integer.313)
-    -- An optional precision that gives the minimum number of digits to appear for the d, i,
-      o, u, x, and X conversions, the number of digits to appear after the decimal-point
-      wide character for a, A, e, E, f, and F conversions, the maximum number of
-      significant digits for the g and G conversions, or the maximum number of wide
-      characters to be written for s conversions. The precision takes the form of a period
-      (.) followed either by an asterisk * (described later) or by an optional decimal
-      integer; if only the period is specified, the precision is taken as zero. If a precision
-      appears with any other conversion specifier, the behavior is undefined.
-    -- An optional length modifier that specifies the size of the argument.
-    -- A conversion specifier wide character that specifies the type of conversion to be
-      applied.
-5   As noted above, a field width, or precision, or both, may be indicated by an asterisk. In
-    this case, an int argument supplies the field width or precision. The arguments
-    specifying field width, or precision, or both, shall appear (in that order) before the
-    argument (if any) to be converted. A negative field width argument is taken as a - flag
-    followed by a positive field width. A negative precision argument is taken as if the
-    precision were omitted.
-6   The flag wide characters and their meanings are:
-    -        The result of the conversion is left-justified within the field. (It is right-justified if
-             this flag is not specified.)
-    +        The result of a signed conversion always begins with a plus or minus sign. (It
-             begins with a sign only when a negative value is converted if this flag is not
-             specified.)314)
-    space If the first wide character of a signed conversion is not a sign, or if a signed
-          conversion results in no wide characters, a space is prefixed to the result. If the
-          space and + flags both appear, the space flag is ignored.
-    #        The result is converted to an ''alternative form''. For o conversion, it increases
-             the precision, if and only if necessary, to force the first digit of the result to be a
-             zero (if the value and precision are both 0, a single 0 is printed). For x (or X)
-             conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,
-
-
-    313) Note that 0 is taken as a flag, not as the beginning of a field width.
-    314) The results of all floating conversions of a negative zero, and of negative values that round to zero,
-         include a minus sign.
-
-[page 400] (Contents)
-
-              and G conversions, the result of converting a floating-point number always
-              contains a decimal-point wide character, even if no digits follow it. (Normally, a
-              decimal-point wide character appears in the result of these conversions only if a
-              digit follows it.) For g and G conversions, trailing zeros are not removed from the
-              result. For other conversions, the behavior is undefined.
-    0         For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-              (following any indication of sign or base) are used to pad to the field width rather
-              than performing space padding, except when converting an infinity or NaN. If the
-              0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X
-              conversions, if a precision is specified, the 0 flag is ignored. For other
-              conversions, the behavior is undefined.
-7   The length modifiers and their meanings are:
-    hh             Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                   signed char or unsigned char argument (the argument will have
-                   been promoted according to the integer promotions, but its value shall be
-                   converted to signed char or unsigned char before printing); or that
-                   a following n conversion specifier applies to a pointer to a signed char
-                   argument.
-    h              Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                   short int or unsigned short int argument (the argument will
-                   have been promoted according to the integer promotions, but its value shall
-                   be converted to short int or unsigned short int before printing);
-                   or that a following n conversion specifier applies to a pointer to a short
-                   int argument.
-    l (ell)        Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                   long int or unsigned long int argument; that a following n
-                   conversion specifier applies to a pointer to a long int argument; that a
-                   following c conversion specifier applies to a wint_t argument; that a
-                   following s conversion specifier applies to a pointer to a wchar_t
-                   argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion
-                   specifier.
-    ll (ell-ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                 long long int or unsigned long long int argument; or that a
-                 following n conversion specifier applies to a pointer to a long long int
-                 argument.
-    j              Specifies that a following d, i, o, u, x, or X conversion specifier applies to
-                   an intmax_t or uintmax_t argument; or that a following n conversion
-                   specifier applies to a pointer to an intmax_t argument.
-
-[page 401] (Contents)
-
-    z           Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                size_t or the corresponding signed integer type argument; or that a
-                following n conversion specifier applies to a pointer to a signed integer type
-                corresponding to size_t argument.
-    t           Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-                ptrdiff_t or the corresponding unsigned integer type argument; or that a
-                following n conversion specifier applies to a pointer to a ptrdiff_t
-                argument.
-    L           Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-                applies to a long double argument.
-    If a length modifier appears with any conversion specifier other than as specified above,
-    the behavior is undefined.
-8   The conversion specifiers and their meanings are:
-    d,i        The int argument is converted to signed decimal in the style [-]dddd. The
-               precision specifies the minimum number of digits to appear; if the value
-               being converted can be represented in fewer digits, it is expanded with
-               leading zeros. The default precision is 1. The result of converting a zero
-               value with a precision of zero is no wide characters.
-    o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned
-            decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the
-            letters abcdef are used for x conversion and the letters ABCDEF for X
-            conversion. The precision specifies the minimum number of digits to appear;
-            if the value being converted can be represented in fewer digits, it is expanded
-            with leading zeros. The default precision is 1. The result of converting a
-            zero value with a precision of zero is no wide characters.
-    f,F        A double argument representing a floating-point number is converted to
-               decimal notation in the style [-]ddd.ddd, where the number of digits after
-               the decimal-point wide character is equal to the precision specification. If the
-               precision is missing, it is taken as 6; if the precision is zero and the # flag is
-               not specified, no decimal-point wide character appears. If a decimal-point
-               wide character appears, at least one digit appears before it. The value is
-               rounded to the appropriate number of digits.
-               A double argument representing an infinity is converted in one of the styles
-               [-]inf or [-]infinity -- which style is implementation-defined. A
-               double argument representing a NaN is converted in one of the styles
-               [-]nan or [-]nan(n-wchar-sequence) -- which style, and the meaning of
-               any n-wchar-sequence, is implementation-defined. The F conversion
-               specifier produces INF, INFINITY, or NAN instead of inf, infinity, or
-
-[page 402] (Contents)
-
-             nan, respectively.315)
-e,E          A double argument representing a floating-point number is converted in the
-             style [-]d.ddd e(+-)dd, where there is one digit (which is nonzero if the
-             argument is nonzero) before the decimal-point wide character and the number
-             of digits after it is equal to the precision; if the precision is missing, it is taken
-             as 6; if the precision is zero and the # flag is not specified, no decimal-point
-             wide character appears. The value is rounded to the appropriate number of
-             digits. The E conversion specifier produces a number with E instead of e
-             introducing the exponent. The exponent always contains at least two digits,
-             and only as many more digits as necessary to represent the exponent. If the
-             value is zero, the exponent is zero.
-             A double argument representing an infinity or NaN is converted in the style
-             of an f or F conversion specifier.
-g,G          A double argument representing a floating-point number is converted in
-             style f or e (or in style F or E in the case of a G conversion specifier),
-             depending on the value converted and the precision. Let P equal the
-             precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero.
-             Then, if a conversion with style E would have an exponent of X:
-             -- if P > X >= -4, the conversion is with style f (or F) and precision
-               P - (X + 1).
-             -- otherwise, the conversion is with style e (or E) and precision P - 1.
-             Finally, unless the # flag is used, any trailing zeros are removed from the
-             fractional portion of the result and the decimal-point wide character is
-             removed if there is no fractional portion remaining.
-             A double argument representing an infinity or NaN is converted in the style
-             of an f or F conversion specifier.
-a,A          A double argument representing a floating-point number is converted in the
-             style [-]0xh.hhhh p(+-)d, where there is one hexadecimal digit (which is
-             nonzero if the argument is a normalized floating-point number and is
-             otherwise unspecified) before the decimal-point wide character316) and the
-             number of hexadecimal digits after it is equal to the precision; if the precision
-             is missing and FLT_RADIX is a power of 2, then the precision is sufficient
-
-
-315) When applied to infinite and NaN values, the -, +, and space flag wide characters have their usual
-     meaning; the # and 0 flag wide characters have no effect.
-316) Binary implementations can choose the hexadecimal digit to the left of the decimal-point wide
-     character so that subsequent digits align to nibble (4-bit) boundaries.
-
-[page 403] (Contents)
-
-             for an exact representation of the value; if the precision is missing and
-             FLT_RADIX is not a power of 2, then the precision is sufficient to
-             distinguish317) values of type double, except that trailing zeros may be
-             omitted; if the precision is zero and the # flag is not specified, no decimal-
-             point wide character appears. The letters abcdef are used for a conversion
-             and the letters ABCDEF for A conversion. The A conversion specifier
-             produces a number with X and P instead of x and p. The exponent always
-             contains at least one digit, and only as many more digits as necessary to
-             represent the decimal exponent of 2. If the value is zero, the exponent is
-             zero.
-             A double argument representing an infinity or NaN is converted in the style
-             of an f or F conversion specifier.
-c            If no l length modifier is present, the int argument is converted to a wide
-             character as if by calling btowc and the resulting wide character is written.
-             If an l length modifier is present, the wint_t argument is converted to
-             wchar_t and written.
-s            If no l length modifier is present, the argument shall be a pointer to the initial
-             element of a character array containing a multibyte character sequence
-             beginning in the initial shift state. Characters from the array are converted as
-             if by repeated calls to the mbrtowc function, with the conversion state
-             described by an mbstate_t object initialized to zero before the first
-             multibyte character is converted, and written up to (but not including) the
-             terminating null wide character. If the precision is specified, no more than
-             that many wide characters are written. If the precision is not specified or is
-             greater than the size of the converted array, the converted array shall contain a
-             null wide character.
-             If an l length modifier is present, the argument shall be a pointer to the initial
-             element of an array of wchar_t type. Wide characters from the array are
-             written up to (but not including) a terminating null wide character. If the
-             precision is specified, no more than that many wide characters are written. If
-             the precision is not specified or is greater than the size of the array, the array
-             shall contain a null wide character.
-p            The argument shall be a pointer to void. The value of the pointer is
-             converted to a sequence of printing wide characters, in an implementation-
-
-317) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
-     FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p
-     might suffice depending on the implementation's scheme for determining the digit to the left of the
-     decimal-point wide character.
-
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-
-                    defined manner.
-     n              The argument shall be a pointer to signed integer into which is written the
-                    number of wide characters written to the output stream so far by this call to
-                    fwprintf. No argument is converted, but one is consumed. If the
-                    conversion specification includes any flags, a field width, or a precision, the
-                    behavior is undefined.
-     %              A % wide character is written. No argument is converted. The complete
-                    conversion specification shall be %%.
-9    If a conversion specification is invalid, the behavior is undefined.318) If any argument is
-     not the correct type for the corresponding conversion specification, the behavior is
-     undefined.
-10   In no case does a nonexistent or small field width cause truncation of a field; if the result
-     of a conversion is wider than the field width, the field is expanded to contain the
-     conversion result.
-11   For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
-     to a hexadecimal floating number with the given precision.
-     Recommended practice
-12   For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
-     representable in the given precision, the result should be one of the two adjacent numbers
-     in hexadecimal floating style with the given precision, with the extra stipulation that the
-     error should have a correct sign for the current rounding direction.
-13   For e, E, f, F, g, and G conversions, if the number of significant decimal digits is at most
-     DECIMAL_DIG, then the result should be correctly rounded.319) If the number of
-     significant decimal digits is more than DECIMAL_DIG but the source value is exactly
-     representable with DECIMAL_DIG digits, then the result should be an exact
-     representation with trailing zeros. Otherwise, the source value is bounded by two
-     adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value
-     of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
-     the error should have a correct sign for the current rounding direction.
-     Returns
-14   The fwprintf function returns the number of wide characters transmitted, or a negative
-     value if an output or encoding error occurred.
-
-     318) See ''future library directions'' (7.30.12).
-     319) For binary-to-decimal conversion, the result format's values are the numbers representable with the
-          given format specifier. The number of significant digits is determined by the format specifier, and in
-          the case of fixed-point conversion by the source value as well.
-
-[page 405] (Contents)
-
-     Environmental limits
-15   The number of wide characters that can be produced by any single conversion shall be at
-     least 4095.
-16   EXAMPLE       To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal
-     places:
-            #include <math.h>
-            #include <stdio.h>
-            #include <wchar.h>
-            /* ... */
-            wchar_t *weekday, *month; // pointers to wide strings
-            int day, hour, min;
-            fwprintf(stdout, L"%ls, %ls %d, %.2d:%.2d\n",
-                    weekday, month, day, hour, min);
-            fwprintf(stdout, L"pi = %.5f\n", 4 * atan(1.0));
-
-     Forward references:          the btowc function (7.28.6.1.1), the mbrtowc function
-     (7.28.6.3.2).
-     7.28.2.2 The fwscanf function
-     Synopsis
-1           #include <stdio.h>
-            #include <wchar.h>
-            int fwscanf(FILE * restrict stream,
-                 const wchar_t * restrict format, ...);
-     Description
-2    The fwscanf function reads input from the stream pointed to by stream, under
-     control of the wide string pointed to by format that specifies the admissible input
-     sequences and how they are to be converted for assignment, using subsequent arguments
-     as pointers to the objects to receive the converted input. If there are insufficient
-     arguments for the format, the behavior is undefined. If the format is exhausted while
-     arguments remain, the excess arguments are evaluated (as always) but are otherwise
-     ignored.
-3    The format is composed of zero or more directives: one or more white-space wide
-     characters, an ordinary wide character (neither % nor a white-space wide character), or a
-     conversion specification. Each conversion specification is introduced by the wide
-     character %. After the %, the following appear in sequence:
-     -- An optional assignment-suppressing wide character *.
-     -- An optional decimal integer greater than zero that specifies the maximum field width
-       (in wide characters).
-
-
-
-[page 406] (Contents)
-
-     -- An optional length modifier that specifies the size of the receiving object.
-     -- A conversion specifier wide character that specifies the type of conversion to be
-       applied.
-4    The fwscanf function executes each directive of the format in turn. When all directives
-     have been executed, or if a directive fails (as detailed below), the function returns.
-     Failures are described as input failures (due to the occurrence of an encoding error or the
-     unavailability of input characters), or matching failures (due to inappropriate input).
-5    A directive composed of white-space wide character(s) is executed by reading input up to
-     the first non-white-space wide character (which remains unread), or until no more wide
-     characters can be read.
-6    A directive that is an ordinary wide character is executed by reading the next wide
-     character of the stream. If that wide character differs from the directive, the directive
-     fails and the differing and subsequent wide characters remain unread. Similarly, if end-
-     of-file, an encoding error, or a read error prevents a wide character from being read, the
-     directive fails.
-7    A directive that is a conversion specification defines a set of matching input sequences, as
-     described below for each specifier. A conversion specification is executed in the
-     following steps:
-8    Input white-space wide characters (as specified by the iswspace function) are skipped,
-     unless the specification includes a [, c, or n specifier.320)
-9    An input item is read from the stream, unless the specification includes an n specifier. An
-     input item is defined as the longest sequence of input wide characters which does not
-     exceed any specified field width and which is, or is a prefix of, a matching input
-     sequence.321) The first wide character, if any, after the input item remains unread. If the
-     length of the input item is zero, the execution of the directive fails; this condition is a
-     matching failure unless end-of-file, an encoding error, or a read error prevented input
-     from the stream, in which case it is an input failure.
-10   Except in the case of a % specifier, the input item (or, in the case of a %n directive, the
-     count of input wide characters) is converted to a type appropriate to the conversion
-     specifier. If the input item is not a matching sequence, the execution of the directive fails:
-     this condition is a matching failure. Unless assignment suppression was indicated by a *,
-     the result of the conversion is placed in the object pointed to by the first argument
-     following the format argument that has not already received a conversion result. If this
-
-
-     320) These white-space wide characters are not counted against a specified field width.
-     321) fwscanf pushes back at most one input wide character onto the input stream. Therefore, some
-          sequences that are acceptable to wcstod, wcstol, etc., are unacceptable to fwscanf.
-
-[page 407] (Contents)
-
-     object does not have an appropriate type, or if the result of the conversion cannot be
-     represented in the object, the behavior is undefined.
-11   The length modifiers and their meanings are:
-     hh          Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to signed char or unsigned char.
-     h           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to short int or unsigned short
-                 int.
-     l (ell)     Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to long int or unsigned long
-                 int; that a following a, A, e, E, f, F, g, or G conversion specifier applies to
-                 an argument with type pointer to double; or that a following c, s, or [
-                 conversion specifier applies to an argument with type pointer to wchar_t.
-     ll (ell-ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                  to an argument with type pointer to long long int or unsigned
-                  long long int.
-     j           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to intmax_t or uintmax_t.
-     z           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to size_t or the corresponding signed
-                 integer type.
-     t           Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-                 to an argument with type pointer to ptrdiff_t or the corresponding
-                 unsigned integer type.
-     L           Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-                 applies to an argument with type pointer to long double.
-     If a length modifier appears with any conversion specifier other than as specified above,
-     the behavior is undefined.
-12   The conversion specifiers and their meanings are:
-     d          Matches an optionally signed decimal integer, whose format is the same as
-                expected for the subject sequence of the wcstol function with the value 10
-                for the base argument. The corresponding argument shall be a pointer to
-                signed integer.
-     i          Matches an optionally signed integer, whose format is the same as expected
-                for the subject sequence of the wcstol function with the value 0 for the
-                base argument. The corresponding argument shall be a pointer to signed
-
-[page 408] (Contents)
-
-            integer.
-o           Matches an optionally signed octal integer, whose format is the same as
-            expected for the subject sequence of the wcstoul function with the value 8
-            for the base argument. The corresponding argument shall be a pointer to
-            unsigned integer.
-u           Matches an optionally signed decimal integer, whose format is the same as
-            expected for the subject sequence of the wcstoul function with the value 10
-            for the base argument. The corresponding argument shall be a pointer to
-            unsigned integer.
-x           Matches an optionally signed hexadecimal integer, whose format is the same
-            as expected for the subject sequence of the wcstoul function with the value
-            16 for the base argument. The corresponding argument shall be a pointer to
-            unsigned integer.
-a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose
-        format is the same as expected for the subject sequence of the wcstod
-        function. The corresponding argument shall be a pointer to floating.
-c           Matches a sequence of wide characters of exactly the number specified by the
-            field width (1 if no field width is present in the directive).
-            If no l length modifier is present, characters from the input field are
-            converted as if by repeated calls to the wcrtomb function, with the
-            conversion state described by an mbstate_t object initialized to zero
-            before the first wide character is converted. The corresponding argument
-            shall be a pointer to the initial element of a character array large enough to
-            accept the sequence. No null character is added.
-            If an l length modifier is present, the corresponding argument shall be a
-            pointer to the initial element of an array of wchar_t large enough to accept
-            the sequence. No null wide character is added.
-s           Matches a sequence of non-white-space wide characters.
-            If no l length modifier is present, characters from the input field are
-            converted as if by repeated calls to the wcrtomb function, with the
-            conversion state described by an mbstate_t object initialized to zero
-            before the first wide character is converted. The corresponding argument
-            shall be a pointer to the initial element of a character array large enough to
-            accept the sequence and a terminating null character, which will be added
-            automatically.
-            If an l length modifier is present, the corresponding argument shall be a
-            pointer to the initial element of an array of wchar_t large enough to accept
-
-[page 409] (Contents)
-
-         the sequence and the terminating null wide character, which will be added
-         automatically.
-[        Matches a nonempty sequence of wide characters from a set of expected
-         characters (the scanset).
-         If no l length modifier is present, characters from the input field are
-         converted as if by repeated calls to the wcrtomb function, with the
-         conversion state described by an mbstate_t object initialized to zero
-         before the first wide character is converted. The corresponding argument
-         shall be a pointer to the initial element of a character array large enough to
-         accept the sequence and a terminating null character, which will be added
-         automatically.
-         If an l length modifier is present, the corresponding argument shall be a
-         pointer to the initial element of an array of wchar_t large enough to accept
-         the sequence and the terminating null wide character, which will be added
-         automatically.
-         The conversion specifier includes all subsequent wide characters in the
-         format string, up to and including the matching right bracket (]). The wide
-         characters between the brackets (the scanlist) compose the scanset, unless the
-         wide character after the left bracket is a circumflex (^), in which case the
-         scanset contains all wide characters that do not appear in the scanlist between
-         the circumflex and the right bracket. If the conversion specifier begins with
-         [] or [^], the right bracket wide character is in the scanlist and the next
-         following right bracket wide character is the matching right bracket that ends
-         the specification; otherwise the first following right bracket wide character is
-         the one that ends the specification. If a - wide character is in the scanlist and
-         is not the first, nor the second where the first wide character is a ^, nor the
-         last character, the behavior is implementation-defined.
-p        Matches an implementation-defined set of sequences, which should be the
-         same as the set of sequences that may be produced by the %p conversion of
-         the fwprintf function. The corresponding argument shall be a pointer to a
-         pointer to void. The input item is converted to a pointer value in an
-         implementation-defined manner. If the input item is a value converted earlier
-         during the same program execution, the pointer that results shall compare
-         equal to that value; otherwise the behavior of the %p conversion is undefined.
-n        No input is consumed. The corresponding argument shall be a pointer to
-         signed integer into which is to be written the number of wide characters read
-         from the input stream so far by this call to the fwscanf function. Execution
-         of a %n directive does not increment the assignment count returned at the
-         completion of execution of the fwscanf function. No argument is
-[page 410] (Contents)
-
-                    converted, but one is consumed. If the conversion specification includes an
-                    assignment-suppressing wide character or a field width, the behavior is
-                    undefined.
-     %              Matches a single % wide character; no conversion or assignment occurs. The
-                    complete conversion specification shall be %%.
-13   If a conversion specification is invalid, the behavior is undefined.322)
-14   The conversion specifiers A, E, F, G, and X are also valid and behave the same as,
-     respectively, a, e, f, g, and x.
-15   Trailing white space (including new-line wide characters) is left unread unless matched
-     by a directive. The success of literal matches and suppressed assignments is not directly
-     determinable other than via the %n directive.
-     Returns
-16   The fwscanf function returns the value of the macro EOF if an input failure occurs
-     before the first conversion (if any) has completed. Otherwise, the function returns the
-     number of input items assigned, which can be fewer than provided for, or even zero, in
-     the event of an early matching failure.
-17   EXAMPLE 1        The call:
-              #include <stdio.h>
-              #include <wchar.h>
-              /* ... */
-              int n, i; float x; wchar_t name[50];
-              n = fwscanf(stdin, L"%d%f%ls", &i, &x, name);
-     with the input line:
-              25 54.32E-1 thompson
-     will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
-     thompson\0.
-
-18   EXAMPLE 2        The call:
-              #include <stdio.h>
-              #include <wchar.h>
-              /* ... */
-              int i; float x; double y;
-              fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y);
-     with input:
-              56789 0123 56a72
-     will assign to i the value 56 and to x the value 789.0, will skip past 0123, and will assign to y the value
-     56.0. The next wide character read from the input stream will be a.
-
-
-     322) See ''future library directions'' (7.30.12).
-
-[page 411] (Contents)
-
-    Forward references: the wcstod, wcstof, and wcstold functions (7.28.4.1.1), the
-    wcstol, wcstoll, wcstoul, and wcstoull functions (7.28.4.1.2), the wcrtomb
-    function (7.28.6.3.3).
-    7.28.2.3 The swprintf function
-    Synopsis
-1          #include <wchar.h>
-           int swprintf(wchar_t * restrict s,
-                size_t n,
-                const wchar_t * restrict format, ...);
-    Description
-2   The swprintf function is equivalent to fwprintf, except that the argument s
-    specifies an array of wide characters into which the generated output is to be written,
-    rather than written to a stream. No more than n wide characters are written, including a
-    terminating null wide character, which is always added (unless n is zero).
-    Returns
-3   The swprintf function returns the number of wide characters written in the array, not
-    counting the terminating null wide character, or a negative value if an encoding error
-    occurred or if n or more wide characters were requested to be written.
-    7.28.2.4 The swscanf function
-    Synopsis
-1          #include <wchar.h>
-           int swscanf(const wchar_t * restrict s,
-                const wchar_t * restrict format, ...);
-    Description
-2   The swscanf function is equivalent to fwscanf, except that the argument s specifies a
-    wide string from which the input is to be obtained, rather than from a stream. Reaching
-    the end of the wide string is equivalent to encountering end-of-file for the fwscanf
-    function.
-    Returns
-3   The swscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the swscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-
-
-
-
-[page 412] (Contents)
-
-    7.28.2.5 The vfwprintf function
-    Synopsis
-1           #include <stdarg.h>
-            #include <stdio.h>
-            #include <wchar.h>
-            int vfwprintf(FILE * restrict stream,
-                 const wchar_t * restrict format,
-                 va_list arg);
-    Description
-2   The vfwprintf function is equivalent to fwprintf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vfwprintf function does not invoke the
-    va_end macro.323)
-    Returns
-3   The vfwprintf function returns the number of wide characters transmitted, or a
-    negative value if an output or encoding error occurred.
-4   EXAMPLE       The following shows the use of the vfwprintf function in a general error-reporting
-    routine.
-            #include <stdarg.h>
-            #include <stdio.h>
-            #include <wchar.h>
-            void error(char *function_name, wchar_t *format, ...)
-            {
-                  va_list args;
-                    va_start(args, format);
-                    // print out name of function causing error
-                    fwprintf(stderr, L"ERROR in %s: ", function_name);
-                    // print out remainder of message
-                    vfwprintf(stderr, format, args);
-                    va_end(args);
-            }
-
-
-
-
-    323) As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
-         invoke the va_arg macro, the value of arg after the return is indeterminate.
-
-[page 413] (Contents)
-
-    7.28.2.6 The vfwscanf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <stdio.h>
-           #include <wchar.h>
-           int vfwscanf(FILE * restrict stream,
-                const wchar_t * restrict format,
-                va_list arg);
-    Description
-2   The vfwscanf function is equivalent to fwscanf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vfwscanf function does not invoke the
-    va_end macro.323)
-    Returns
-3   The vfwscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the vfwscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.28.2.7 The vswprintf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <wchar.h>
-           int vswprintf(wchar_t * restrict s,
-                size_t n,
-                const wchar_t * restrict format,
-                va_list arg);
-    Description
-2   The vswprintf function is equivalent to swprintf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vswprintf function does not invoke the
-    va_end macro.323)
-    Returns
-3   The vswprintf function returns the number of wide characters written in the array, not
-    counting the terminating null wide character, or a negative value if an encoding error
-    occurred or if n or more wide characters were requested to be generated.
-
-
-[page 414] (Contents)
-
-    7.28.2.8 The vswscanf function
-    Synopsis
-1           #include <stdarg.h>
-            #include <wchar.h>
-            int vswscanf(const wchar_t * restrict s,
-                 const wchar_t * restrict format,
-                 va_list arg);
-    Description
-2   The vswscanf function is equivalent to swscanf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vswscanf function does not invoke the
-    va_end macro.323)
-    Returns
-3   The vswscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the vswscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.28.2.9 The vwprintf function
-    Synopsis
-1           #include <stdarg.h>
-            #include <wchar.h>
-            int vwprintf(const wchar_t * restrict format,
-                 va_list arg);
-    Description
-2   The vwprintf function is equivalent to wprintf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vwprintf function does not invoke the
-    va_end macro.323)
-    Returns
-3   The vwprintf function returns the number of wide characters transmitted, or a negative
-    value if an output or encoding error occurred.
-
-
-
-
-[page 415] (Contents)
-
-    7.28.2.10 The vwscanf function
-    Synopsis
-1          #include <stdarg.h>
-           #include <wchar.h>
-           int vwscanf(const wchar_t * restrict format,
-                va_list arg);
-    Description
-2   The vwscanf function is equivalent to wscanf, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vwscanf function does not invoke the
-    va_end macro.323)
-    Returns
-3   The vwscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the vwscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.28.2.11 The wprintf function
-    Synopsis
-1          #include <wchar.h>
-           int wprintf(const wchar_t * restrict format, ...);
-    Description
-2   The wprintf function is equivalent to fwprintf with the argument stdout
-    interposed before the arguments to wprintf.
-    Returns
-3   The wprintf function returns the number of wide characters transmitted, or a negative
-    value if an output or encoding error occurred.
-    7.28.2.12 The wscanf function
-    Synopsis
-1          #include <wchar.h>
-           int wscanf(const wchar_t * restrict format, ...);
-    Description
-2   The wscanf function is equivalent to fwscanf with the argument stdin interposed
-    before the arguments to wscanf.
-
-
-[page 416] (Contents)
-
-    Returns
-3   The wscanf function returns the value of the macro EOF if an input failure occurs
-    before the first conversion (if any) has completed. Otherwise, the wscanf function
-    returns the number of input items assigned, which can be fewer than provided for, or even
-    zero, in the event of an early matching failure.
-    7.28.3 Wide character input/output functions
-    7.28.3.1 The fgetwc function
-    Synopsis
-1           #include <stdio.h>
-            #include <wchar.h>
-            wint_t fgetwc(FILE *stream);
-    Description
-2   If the end-of-file indicator for the input stream pointed to by stream is not set and a
-    next wide character is present, the fgetwc function obtains that wide character as a
-    wchar_t converted to a wint_t and advances the associated file position indicator for
-    the stream (if defined).
-    Returns
-3   If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
-    of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise,
-    the fgetwc function returns the next wide character from the input stream pointed to by
-    stream. If a read error occurs, the error indicator for the stream is set and the fgetwc
-    function returns WEOF. If an encoding error occurs (including too few bytes), the value of
-    the macro EILSEQ is stored in errno and the fgetwc function returns WEOF.324)
-    7.28.3.2 The fgetws function
-    Synopsis
-1           #include <stdio.h>
-            #include <wchar.h>
-            wchar_t *fgetws(wchar_t * restrict s,
-                 int n, FILE * restrict stream);
-    Description
-2   The fgetws function reads at most one less than the number of wide characters
-    specified by n from the stream pointed to by stream into the array pointed to by s. No
-
-
-    324) An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
-         Also, errno will be set to EILSEQ by input/output functions only if an encoding error occurs.
-
-[page 417] (Contents)
-
-    additional wide characters are read after a new-line wide character (which is retained) or
-    after end-of-file. A null wide character is written immediately after the last wide
-    character read into the array.
-    Returns
-3   The fgetws function returns s if successful. If end-of-file is encountered and no
-    characters have been read into the array, the contents of the array remain unchanged and a
-    null pointer is returned. If a read or encoding error occurs during the operation, the array
-    contents are indeterminate and a null pointer is returned.
-    7.28.3.3 The fputwc function
-    Synopsis
-1          #include <stdio.h>
-           #include <wchar.h>
-           wint_t fputwc(wchar_t c, FILE *stream);
-    Description
-2   The fputwc function writes the wide character specified by c to the output stream
-    pointed to by stream, at the position indicated by the associated file position indicator
-    for the stream (if defined), and advances the indicator appropriately. If the file cannot
-    support positioning requests, or if the stream was opened with append mode, the
-    character is appended to the output stream.
-    Returns
-3   The fputwc function returns the wide character written. If a write error occurs, the
-    error indicator for the stream is set and fputwc returns WEOF. If an encoding error
-    occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF.
-    7.28.3.4 The fputws function
-    Synopsis
-1          #include <stdio.h>
-           #include <wchar.h>
-           int fputws(const wchar_t * restrict s,
-                FILE * restrict stream);
-    Description
-2   The fputws function writes the wide string pointed to by s to the stream pointed to by
-    stream. The terminating null wide character is not written.
-    Returns
-3   The fputws function returns EOF if a write or encoding error occurs; otherwise, it
-    returns a nonnegative value.
-
-[page 418] (Contents)
-
-    7.28.3.5 The fwide function
-    Synopsis
-1           #include <stdio.h>
-            #include <wchar.h>
-            int fwide(FILE *stream, int mode);
-    Description
-2   The fwide function determines the orientation of the stream pointed to by stream. If
-    mode is greater than zero, the function first attempts to make the stream wide oriented. If
-    mode is less than zero, the function first attempts to make the stream byte oriented.325)
-    Otherwise, mode is zero and the function does not alter the orientation of the stream.
-    Returns
-3   The fwide function returns a value greater than zero if, after the call, the stream has
-    wide orientation, a value less than zero if the stream has byte orientation, or zero if the
-    stream has no orientation.
-    7.28.3.6 The getwc function
-    Synopsis
-1           #include <stdio.h>
-            #include <wchar.h>
-            wint_t getwc(FILE *stream);
-    Description
-2   The getwc function is equivalent to fgetwc, except that if it is implemented as a
-    macro, it may evaluate stream more than once, so the argument should never be an
-    expression with side effects.
-    Returns
-3   The getwc function returns the next wide character from the input stream pointed to by
-    stream, or WEOF.
-    7.28.3.7 The getwchar function
-    Synopsis
-1           #include <wchar.h>
-            wint_t getwchar(void);
-
-
-
-
-    325) If the orientation of the stream has already been determined, fwide does not change it.
-
-[page 419] (Contents)
-
-    Description
-2   The getwchar function is equivalent to getwc with the argument stdin.
-    Returns
-3   The getwchar function returns the next wide character from the input stream pointed to
-    by stdin, or WEOF.
-    7.28.3.8 The putwc function
-    Synopsis
-1          #include <stdio.h>
-           #include <wchar.h>
-           wint_t putwc(wchar_t c, FILE *stream);
-    Description
-2   The putwc function is equivalent to fputwc, except that if it is implemented as a
-    macro, it may evaluate stream more than once, so that argument should never be an
-    expression with side effects.
-    Returns
-3   The putwc function returns the wide character written, or WEOF.
-    7.28.3.9 The putwchar function
-    Synopsis
-1          #include <wchar.h>
-           wint_t putwchar(wchar_t c);
-    Description
-2   The putwchar function is equivalent to putwc with the second argument stdout.
-    Returns
-3   The putwchar function returns the character written, or WEOF.
-    7.28.3.10 The ungetwc function
-    Synopsis
-1          #include <stdio.h>
-           #include <wchar.h>
-           wint_t ungetwc(wint_t c, FILE *stream);
-    Description
-2   The ungetwc function pushes the wide character specified by c back onto the input
-    stream pointed to by stream. Pushed-back wide characters will be returned by
-    subsequent reads on that stream in the reverse order of their pushing. A successful
-
-[page 420] (Contents)
-
-    intervening call (with the stream pointed to by stream) to a file positioning function
-    (fseek, fsetpos, or rewind) discards any pushed-back wide characters for the
-    stream. The external storage corresponding to the stream is unchanged.
-3   One wide character of pushback is guaranteed, even if the call to the ungetwc function
-    follows just after a call to a formatted wide character input function fwscanf,
-    vfwscanf, vwscanf, or wscanf. If the ungetwc function is called too many times
-    on the same stream without an intervening read or file positioning operation on that
-    stream, the operation may fail.
-4   If the value of c equals that of the macro WEOF, the operation fails and the input stream is
-    unchanged.
-5   A successful call to the ungetwc function clears the end-of-file indicator for the stream.
-    The value of the file position indicator for the stream after reading or discarding all
-    pushed-back wide characters is the same as it was before the wide characters were pushed
-    back. For a text or binary stream, the value of its file position indicator after a successful
-    call to the ungetwc function is unspecified until all pushed-back wide characters are
-    read or discarded.
-    Returns
-6   The ungetwc function returns the wide character pushed back, or WEOF if the operation
-    fails.
-    7.28.4 General wide string utilities
-1   The header <wchar.h> declares a number of functions useful for wide string
-    manipulation. Various methods are used for determining the lengths of the arrays, but in
-    all cases a wchar_t * argument points to the initial (lowest addressed) element of the
-    array. If an array is accessed beyond the end of an object, the behavior is undefined.
-2   Where an argument declared as size_t n determines the length of the array for a
-    function, n can have the value zero on a call to that function. Unless explicitly stated
-    otherwise in the description of a particular function in this subclause, pointer arguments
-    on such a call shall still have valid values, as described in 7.1.4. On such a call, a
-    function that locates a wide character finds no occurrence, a function that compares two
-    wide character sequences returns zero, and a function that copies wide characters copies
-    zero wide characters.
-
-
-
-
-[page 421] (Contents)
-
-    7.28.4.1 Wide string numeric conversion functions
-    7.28.4.1.1 The wcstod, wcstof, and wcstold functions
-    Synopsis
-1          #include <wchar.h>
-           double wcstod(const wchar_t * restrict nptr,
-                wchar_t ** restrict endptr);
-           float wcstof(const wchar_t * restrict nptr,
-                wchar_t ** restrict endptr);
-           long double wcstold(const wchar_t * restrict nptr,
-                wchar_t ** restrict endptr);
-    Description
-2   The wcstod, wcstof, and wcstold functions convert the initial portion of the wide
-    string pointed to by nptr to double, float, and long double representation,
-    respectively. First, they decompose the input string into three parts: an initial, possibly
-    empty, sequence of white-space wide characters (as specified by the iswspace
-    function), a subject sequence resembling a floating-point constant or representing an
-    infinity or NaN; and a final wide string of one or more unrecognized wide characters,
-    including the terminating null wide character of the input wide string. Then, they attempt
-    to convert the subject sequence to a floating-point number, and return the result.
-3   The expected form of the subject sequence is an optional plus or minus sign, then one of
-    the following:
-    -- a nonempty sequence of decimal digits optionally containing a decimal-point wide
-      character, then an optional exponent part as defined for the corresponding single-byte
-      characters in 6.4.4.2;
-    -- a 0x or 0X, then a nonempty sequence of hexadecimal digits optionally containing a
-      decimal-point wide character, then an optional binary exponent part as defined in
-      6.4.4.2;
-    -- INF or INFINITY, or any other wide string equivalent except for case
-    -- NAN or NAN(n-wchar-sequenceopt), or any other wide string equivalent except for
-      case in the NAN part, where:
-               n-wchar-sequence:
-                     digit
-                     nondigit
-                     n-wchar-sequence digit
-                     n-wchar-sequence nondigit
-    The subject sequence is defined as the longest initial subsequence of the input wide
-    string, starting with the first non-white-space wide character, that is of the expected form.
-[page 422] (Contents)
-
-    The subject sequence contains no wide characters if the input wide string is not of the
-    expected form.
-4   If the subject sequence has the expected form for a floating-point number, the sequence of
-    wide characters starting with the first digit or the decimal-point wide character
-    (whichever occurs first) is interpreted as a floating constant according to the rules of
-    6.4.4.2, except that the decimal-point wide character is used in place of a period, and that
-    if neither an exponent part nor a decimal-point wide character appears in a decimal
-    floating point number, or if a binary exponent part does not appear in a hexadecimal
-    floating point number, an exponent part of the appropriate type with value zero is
-    assumed to follow the last digit in the string. If the subject sequence begins with a minus
-    sign, the sequence is interpreted as negated.326) A wide character sequence INF or
-    INFINITY is interpreted as an infinity, if representable in the return type, else like a
-    floating constant that is too large for the range of the return type. A wide character
-    sequence NAN or NAN(n-wchar-sequenceopt) is interpreted as a quiet NaN, if supported
-    in the return type, else like a subject sequence part that does not have the expected form;
-    the meaning of the n-wchar sequences is implementation-defined.327) A pointer to the
-    final wide string is stored in the object pointed to by endptr, provided that endptr is
-    not a null pointer.
-5   If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
-    value resulting from the conversion is correctly rounded.
-6   In other than the "C" locale, additional locale-specific subject sequence forms may be
-    accepted.
-7   If the subject sequence is empty or does not have the expected form, no conversion is
-    performed; the value of nptr is stored in the object pointed to by endptr, provided
-    that endptr is not a null pointer.
-    Recommended practice
-8   If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
-    the result is not exactly representable, the result should be one of the two numbers in the
-    appropriate internal format that are adjacent to the hexadecimal floating source value,
-    with the extra stipulation that the error should have a correct sign for the current rounding
-    direction.
-
-
-
-    326) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
-         negating the value resulting from converting the corresponding unsigned sequence (see F.5); the two
-         methods may yield different results if rounding is toward positive or negative infinity. In either case,
-         the functions honor the sign of zero if floating-point arithmetic supports signed zeros.
-    327) An implementation may use the n-wchar sequence to determine extra information to be represented in
-         the NaN's significand.
-
-[page 423] (Contents)
-
-9    If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in
-     <float.h>) significant digits, the result should be correctly rounded. If the subject
-     sequence D has the decimal form and more than DECIMAL_DIG significant digits,
-     consider the two bounding, adjacent decimal strings L and U, both having
-     DECIMAL_DIG significant digits, such that the values of L, D, and U satisfy L <= D <= U.
-     The result should be one of the (equal or adjacent) values that would be obtained by
-     correctly rounding L and U according to the current rounding direction, with the extra
-     stipulation that the error with respect to D should have a correct sign for the current
-     rounding direction.328)
-     Returns
-10   The functions return the converted value, if any. If no conversion could be performed,
-     zero is returned. If the correct value overflows and default rounding is in effect (7.12.1),
-     plus or minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the
-     return type and sign of the value), and the value of the macro ERANGE is stored in
-     errno. If the result underflows (7.12.1), the functions return a value whose magnitude is
-     no greater than the smallest normalized positive number in the return type; whether
-     errno acquires the value ERANGE is implementation-defined.
-
-
-
-
-     328) DECIMAL_DIG, defined in <float.h>, should be sufficiently large that L and U will usually round
-          to the same internal floating value, but if not will round to adjacent values.
-
-[page 424] (Contents)
-
-    7.28.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions
-    Synopsis
-1           #include <wchar.h>
-            long int wcstol(
-                 const wchar_t * restrict nptr,
-                 wchar_t ** restrict endptr,
-                 int base);
-            long long int wcstoll(
-                 const wchar_t * restrict nptr,
-                 wchar_t ** restrict endptr,
-                 int base);
-            unsigned long int wcstoul(
-                 const wchar_t * restrict nptr,
-                 wchar_t ** restrict endptr,
-                 int base);
-            unsigned long long int wcstoull(
-                 const wchar_t * restrict nptr,
-                 wchar_t ** restrict endptr,
-                 int base);
-    Description
-2   The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
-    portion of the wide string pointed to by nptr to long int, long long int,
-    unsigned long int, and unsigned long long int representation,
-    respectively. First, they decompose the input string into three parts: an initial, possibly
-    empty, sequence of white-space wide characters (as specified by the iswspace
-    function), a subject sequence resembling an integer represented in some radix determined
-    by the value of base, and a final wide string of one or more unrecognized wide
-    characters, including the terminating null wide character of the input wide string. Then,
-    they attempt to convert the subject sequence to an integer, and return the result.
-3   If the value of base is zero, the expected form of the subject sequence is that of an
-    integer constant as described for the corresponding single-byte characters in 6.4.4.1,
-    optionally preceded by a plus or minus sign, but not including an integer suffix. If the
-    value of base is between 2 and 36 (inclusive), the expected form of the subject sequence
-    is a sequence of letters and digits representing an integer with the radix specified by
-    base, optionally preceded by a plus or minus sign, but not including an integer suffix.
-    The letters from a (or A) through z (or Z) are ascribed the values 10 through 35; only
-    letters and digits whose ascribed values are less than that of base are permitted. If the
-    value of base is 16, the wide characters 0x or 0X may optionally precede the sequence
-    of letters and digits, following the sign if present.
-
-[page 425] (Contents)
-
-4   The subject sequence is defined as the longest initial subsequence of the input wide
-    string, starting with the first non-white-space wide character, that is of the expected form.
-    The subject sequence contains no wide characters if the input wide string is empty or
-    consists entirely of white space, or if the first non-white-space wide character is other
-    than a sign or a permissible letter or digit.
-5   If the subject sequence has the expected form and the value of base is zero, the sequence
-    of wide characters starting with the first digit is interpreted as an integer constant
-    according to the rules of 6.4.4.1. If the subject sequence has the expected form and the
-    value of base is between 2 and 36, it is used as the base for conversion, ascribing to each
-    letter its value as given above. If the subject sequence begins with a minus sign, the value
-    resulting from the conversion is negated (in the return type). A pointer to the final wide
-    string is stored in the object pointed to by endptr, provided that endptr is not a null
-    pointer.
-6   In other than the "C" locale, additional locale-specific subject sequence forms may be
-    accepted.
-7   If the subject sequence is empty or does not have the expected form, no conversion is
-    performed; the value of nptr is stored in the object pointed to by endptr, provided
-    that endptr is not a null pointer.
-    Returns
-8   The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted
-    value, if any. If no conversion could be performed, zero is returned. If the correct value
-    is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN,
-    LLONG_MAX, ULONG_MAX, or ULLONG_MAX is returned (according to the return type
-    sign of the value, if any), and the value of the macro ERANGE is stored in errno.
-    7.28.4.2 Wide string copying functions
-    7.28.4.2.1 The wcscpy function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wcscpy(wchar_t * restrict s1,
-                const wchar_t * restrict s2);
-    Description
-2   The wcscpy function copies the wide string pointed to by s2 (including the terminating
-    null wide character) into the array pointed to by s1.
-    Returns
-3   The wcscpy function returns the value of s1.
-
-
-[page 426] (Contents)
-
-    7.28.4.2.2 The wcsncpy function
-    Synopsis
-1            #include <wchar.h>
-             wchar_t *wcsncpy(wchar_t * restrict s1,
-                  const wchar_t * restrict s2,
-                  size_t n);
-    Description
-2   The wcsncpy function copies not more than n wide characters (those that follow a null
-    wide character are not copied) from the array pointed to by s2 to the array pointed to by
-    s1.329)
-3   If the array pointed to by s2 is a wide string that is shorter than n wide characters, null
-    wide characters are appended to the copy in the array pointed to by s1, until n wide
-    characters in all have been written.
-    Returns
-4   The wcsncpy function returns the value of s1.
-    7.28.4.2.3 The wmemcpy function
-    Synopsis
-1            #include <wchar.h>
-             wchar_t *wmemcpy(wchar_t * restrict s1,
-                  const wchar_t * restrict s2,
-                  size_t n);
-    Description
-2   The wmemcpy function copies n wide characters from the object pointed to by s2 to the
-    object pointed to by s1.
-    Returns
-3   The wmemcpy function returns the value of s1.
-
-
-
-
-    329) Thus, if there is no null wide character in the first n wide characters of the array pointed to by s2, the
-         result will not be null-terminated.
-
-[page 427] (Contents)
-
-    7.28.4.2.4 The wmemmove function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
-                size_t n);
-    Description
-2   The wmemmove function copies n wide characters from the object pointed to by s2 to
-    the object pointed to by s1. Copying takes place as if the n wide characters from the
-    object pointed to by s2 are first copied into a temporary array of n wide characters that
-    does not overlap the objects pointed to by s1 or s2, and then the n wide characters from
-    the temporary array are copied into the object pointed to by s1.
-    Returns
-3   The wmemmove function returns the value of s1.
-    7.28.4.3 Wide string concatenation functions
-    7.28.4.3.1 The wcscat function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wcscat(wchar_t * restrict s1,
-                const wchar_t * restrict s2);
-    Description
-2   The wcscat function appends a copy of the wide string pointed to by s2 (including the
-    terminating null wide character) to the end of the wide string pointed to by s1. The initial
-    wide character of s2 overwrites the null wide character at the end of s1.
-    Returns
-3   The wcscat function returns the value of s1.
-    7.28.4.3.2 The wcsncat function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wcsncat(wchar_t * restrict s1,
-                const wchar_t * restrict s2,
-                size_t n);
-    Description
-2   The wcsncat function appends not more than n wide characters (a null wide character
-    and those that follow it are not appended) from the array pointed to by s2 to the end of
-
-[page 428] (Contents)
-
-    the wide string pointed to by s1. The initial wide character of s2 overwrites the null
-    wide character at the end of s1. A terminating null wide character is always appended to
-    the result.330)
-    Returns
-3   The wcsncat function returns the value of s1.
-    7.28.4.4 Wide string comparison functions
-1   Unless explicitly stated otherwise, the functions described in this subclause order two
-    wide characters the same way as two integers of the underlying integer type designated
-    by wchar_t.
-    7.28.4.4.1 The wcscmp function
-    Synopsis
-1           #include <wchar.h>
-            int wcscmp(const wchar_t *s1, const wchar_t *s2);
-    Description
-2   The wcscmp function compares the wide string pointed to by s1 to the wide string
-    pointed to by s2.
-    Returns
-3   The wcscmp function returns an integer greater than, equal to, or less than zero,
-    accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
-    wide string pointed to by s2.
-    7.28.4.4.2 The wcscoll function
-    Synopsis
-1           #include <wchar.h>
-            int wcscoll(const wchar_t *s1, const wchar_t *s2);
-    Description
-2   The wcscoll function compares the wide string pointed to by s1 to the wide string
-    pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the
-    current locale.
-    Returns
-3   The wcscoll function returns an integer greater than, equal to, or less than zero,
-    accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
-
-
-    330) Thus, the maximum number of wide characters that can end up in the array pointed to by s1 is
-         wcslen(s1)+n+1.
-
-[page 429] (Contents)
-
-    wide string pointed to by s2 when both are interpreted as appropriate to the current
-    locale.
-    7.28.4.4.3 The wcsncmp function
-    Synopsis
-1          #include <wchar.h>
-           int wcsncmp(const wchar_t *s1, const wchar_t *s2,
-                size_t n);
-    Description
-2   The wcsncmp function compares not more than n wide characters (those that follow a
-    null wide character are not compared) from the array pointed to by s1 to the array
-    pointed to by s2.
-    Returns
-3   The wcsncmp function returns an integer greater than, equal to, or less than zero,
-    accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
-    to, or less than the possibly null-terminated array pointed to by s2.
-    7.28.4.4.4 The wcsxfrm function
-    Synopsis
-1          #include <wchar.h>
-           size_t wcsxfrm(wchar_t * restrict s1,
-                const wchar_t * restrict s2,
-                size_t n);
-    Description
-2   The wcsxfrm function transforms the wide string pointed to by s2 and places the
-    resulting wide string into the array pointed to by s1. The transformation is such that if
-    the wcscmp function is applied to two transformed wide strings, it returns a value greater
-    than, equal to, or less than zero, corresponding to the result of the wcscoll function
-    applied to the same two original wide strings. No more than n wide characters are placed
-    into the resulting array pointed to by s1, including the terminating null wide character. If
-    n is zero, s1 is permitted to be a null pointer.
-    Returns
-3   The wcsxfrm function returns the length of the transformed wide string (not including
-    the terminating null wide character). If the value returned is n or greater, the contents of
-    the array pointed to by s1 are indeterminate.
-4   EXAMPLE The value of the following expression is the length of the array needed to hold the
-    transformation of the wide string pointed to by s:
-
-
-[page 430] (Contents)
-
-            1 + wcsxfrm(NULL, s, 0)
-
-    7.28.4.4.5 The wmemcmp function
-    Synopsis
-1           #include <wchar.h>
-            int wmemcmp(const wchar_t *s1, const wchar_t *s2,
-                 size_t n);
-    Description
-2   The wmemcmp function compares the first n wide characters of the object pointed to by
-    s1 to the first n wide characters of the object pointed to by s2.
-    Returns
-3   The wmemcmp function returns an integer greater than, equal to, or less than zero,
-    accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
-    pointed to by s2.
-    7.28.4.5 Wide string search functions
-    7.28.4.5.1 The wcschr function
-    Synopsis
-1           #include <wchar.h>
-            wchar_t *wcschr(const wchar_t *s, wchar_t c);
-    Description
-2   The wcschr function locates the first occurrence of c in the wide string pointed to by s.
-    The terminating null wide character is considered to be part of the wide string.
-    Returns
-3   The wcschr function returns a pointer to the located wide character, or a null pointer if
-    the wide character does not occur in the wide string.
-    7.28.4.5.2 The wcscspn function
-    Synopsis
-1           #include <wchar.h>
-            size_t wcscspn(const wchar_t *s1, const wchar_t *s2);
-    Description
-2   The wcscspn function computes the length of the maximum initial segment of the wide
-    string pointed to by s1 which consists entirely of wide characters not from the wide
-    string pointed to by s2.
-
-
-
-[page 431] (Contents)
-
-    Returns
-3   The wcscspn function returns the length of the segment.
-    7.28.4.5.3 The wcspbrk function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);
-    Description
-2   The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of
-    any wide character from the wide string pointed to by s2.
-    Returns
-3   The wcspbrk function returns a pointer to the wide character in s1, or a null pointer if
-    no wide character from s2 occurs in s1.
-    7.28.4.5.4 The wcsrchr function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
-    Description
-2   The wcsrchr function locates the last occurrence of c in the wide string pointed to by
-    s. The terminating null wide character is considered to be part of the wide string.
-    Returns
-3   The wcsrchr function returns a pointer to the wide character, or a null pointer if c does
-    not occur in the wide string.
-    7.28.4.5.5 The wcsspn function
-    Synopsis
-1          #include <wchar.h>
-           size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
-    Description
-2   The wcsspn function computes the length of the maximum initial segment of the wide
-    string pointed to by s1 which consists entirely of wide characters from the wide string
-    pointed to by s2.
-    Returns
-3   The wcsspn function returns the length of the segment.
-
-
-[page 432] (Contents)
-
-    7.28.4.5.6 The wcsstr function
-    Synopsis
-1           #include <wchar.h>
-            wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);
-    Description
-2   The wcsstr function locates the first occurrence in the wide string pointed to by s1 of
-    the sequence of wide characters (excluding the terminating null wide character) in the
-    wide string pointed to by s2.
-    Returns
-3   The wcsstr function returns a pointer to the located wide string, or a null pointer if the
-    wide string is not found. If s2 points to a wide string with zero length, the function
-    returns s1.
-    7.28.4.5.7 The wcstok function
-    Synopsis
-1           #include <wchar.h>
-            wchar_t *wcstok(wchar_t * restrict s1,
-                 const wchar_t * restrict s2,
-                 wchar_t ** restrict ptr);
-    Description
-2   A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into
-    a sequence of tokens, each of which is delimited by a wide character from the wide string
-    pointed to by s2. The third argument points to a caller-provided wchar_t pointer into
-    which the wcstok function stores information necessary for it to continue scanning the
-    same wide string.
-3   The first call in a sequence has a non-null first argument and stores an initial value in the
-    object pointed to by ptr. Subsequent calls in the sequence have a null first argument and
-    the object pointed to by ptr is required to have the value stored by the previous call in
-    the sequence, which is then updated. The separator wide string pointed to by s2 may be
-    different from call to call.
-4   The first call in the sequence searches the wide string pointed to by s1 for the first wide
-    character that is not contained in the current separator wide string pointed to by s2. If no
-    such wide character is found, then there are no tokens in the wide string pointed to by s1
-    and the wcstok function returns a null pointer. If such a wide character is found, it is
-    the start of the first token.
-5   The wcstok function then searches from there for a wide character that is contained in
-    the current separator wide string. If no such wide character is found, the current token
-[page 433] (Contents)
-
-    extends to the end of the wide string pointed to by s1, and subsequent searches in the
-    same wide string for a token return a null pointer. If such a wide character is found, it is
-    overwritten by a null wide character, which terminates the current token.
-6   In all cases, the wcstok function stores sufficient information in the pointer pointed to
-    by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
-    value for ptr, shall start searching just past the element overwritten by a null wide
-    character (if any).
-    Returns
-7   The wcstok function returns a pointer to the first wide character of a token, or a null
-    pointer if there is no token.
-8   EXAMPLE
-           #include <wchar.h>
-           static wchar_t str1[] = L"?a???b,,,#c";
-           static wchar_t str2[] = L"\t \t";
-           wchar_t *t, *ptr1, *ptr2;
-           t   =   wcstok(str1,   L"?", &ptr1);          //   t   points to the token L"a"
-           t   =   wcstok(NULL,   L",", &ptr1);          //   t   points to the token L"??b"
-           t   =   wcstok(str2,   L" \t", &ptr2);        //   t   is a null pointer
-           t   =   wcstok(NULL,   L"#,", &ptr1);         //   t   points to the token L"c"
-           t   =   wcstok(NULL,   L"?", &ptr1);          //   t   is a null pointer
-
-    7.28.4.5.8 The wmemchr function
-    Synopsis
-1          #include <wchar.h>
-           wchar_t *wmemchr(const wchar_t *s, wchar_t c,
-                size_t n);
-    Description
-2   The wmemchr function locates the first occurrence of c in the initial n wide characters of
-    the object pointed to by s.
-    Returns
-3   The wmemchr function returns a pointer to the located wide character, or a null pointer if
-    the wide character does not occur in the object.
-
-
-
-
-[page 434] (Contents)
-
-    7.28.4.6 Miscellaneous functions
-    7.28.4.6.1 The wcslen function
-    Synopsis
-1           #include <wchar.h>
-            size_t wcslen(const wchar_t *s);
-    Description
-2   The wcslen function computes the length of the wide string pointed to by s.
-    Returns
-3   The wcslen function returns the number of wide characters that precede the terminating
-    null wide character.
-    7.28.4.6.2 The wmemset function
-    Synopsis
-1           #include <wchar.h>
-            wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
-    Description
-2   The wmemset function copies the value of c into each of the first n wide characters of
-    the object pointed to by s.
-    Returns
-3   The wmemset function returns the value of s.
-    7.28.5 Wide character time conversion functions
-    7.28.5.1 The wcsftime function
-    Synopsis
-1           #include <time.h>
-            #include <wchar.h>
-            size_t wcsftime(wchar_t * restrict s,
-                 size_t maxsize,
-                 const wchar_t * restrict format,
-                 const struct tm * restrict timeptr);
-    Description
-2   The wcsftime function is equivalent to the strftime function, except that:
-    -- The argument s points to the initial element of an array of wide characters into which
-      the generated output is to be placed.
-
-
-[page 435] (Contents)
-
-    -- The argument maxsize indicates the limiting number of wide characters.
-    -- The argument format is a wide string and the conversion specifiers are replaced by
-      corresponding sequences of wide characters.
-    -- The return value indicates the number of wide characters.
-    Returns
-3   If the total number of resulting wide characters including the terminating null wide
-    character is not more than maxsize, the wcsftime function returns the number of
-    wide characters placed into the array pointed to by s not including the terminating null
-    wide character. Otherwise, zero is returned and the contents of the array are
-    indeterminate.
-    7.28.6 Extended multibyte/wide character conversion utilities
-1   The header <wchar.h> declares an extended set of functions useful for conversion
-    between multibyte characters and wide characters.
-2   Most of the following functions -- those that are listed as ''restartable'', 7.28.6.3 and
-    7.28.6.4 -- take as a last argument a pointer to an object of type mbstate_t that is used
-    to describe the current conversion state from a particular multibyte character sequence to
-    a wide character sequence (or the reverse) under the rules of a particular setting for the
-    LC_CTYPE category of the current locale.
-3   The initial conversion state corresponds, for a conversion in either direction, to the
-    beginning of a new multibyte character in the initial shift state. A zero-valued
-    mbstate_t object is (at least) one way to describe an initial conversion state. A zero-
-    valued mbstate_t object can be used to initiate conversion involving any multibyte
-    character sequence, in any LC_CTYPE category setting. If an mbstate_t object has
-    been altered by any of the functions described in this subclause, and is then used with a
-    different multibyte character sequence, or in the other conversion direction, or with a
-    different LC_CTYPE category setting than on earlier function calls, the behavior is
-    undefined.331)
-4   On entry, each function takes the described conversion state (either internal or pointed to
-    by an argument) as current. The conversion state described by the referenced object is
-    altered as needed to track the shift state, and the position within a multibyte character, for
-    the associated multibyte character sequence.
-
-
-
-
-    331) Thus, a particular mbstate_t object can be used, for example, with both the mbrtowc and
-         mbsrtowcs functions as long as they are used to step sequentially through the same multibyte
-         character string.
-
-[page 436] (Contents)
-
-    7.28.6.1 Single-byte/wide character conversion functions
-    7.28.6.1.1 The btowc function
-    Synopsis
-1           #include <wchar.h>                                                                       *
-            wint_t btowc(int c);
-    Description
-2   The btowc function determines whether c constitutes a valid single-byte character in the
-    initial shift state.
-    Returns
-3   The btowc function returns WEOF if c has the value EOF or if (unsigned char)c
-    does not constitute a valid single-byte character in the initial shift state. Otherwise, it
-    returns the wide character representation of that character.
-    7.28.6.1.2 The wctob function
-    Synopsis
-1           #include <wchar.h>                                                                       *
-            int wctob(wint_t c);
-    Description
-2   The wctob function determines whether c corresponds to a member of the extended
-    character set whose multibyte character representation is a single byte when in the initial
-    shift state.
-    Returns
-3   The wctob function returns EOF if c does not correspond to a multibyte character with
-    length one in the initial shift state. Otherwise, it returns the single-byte representation of
-    that character as an unsigned char converted to an int.
-    7.28.6.2 Conversion state functions
-    7.28.6.2.1 The mbsinit function
-    Synopsis
-1           #include <wchar.h>
-            int mbsinit(const mbstate_t *ps);
-    Description
-2   If ps is not a null pointer, the mbsinit function determines whether the referenced
-    mbstate_t object describes an initial conversion state.
-
-
-
-[page 437] (Contents)
-
-    Returns
-3   The mbsinit function returns nonzero if ps is a null pointer or if the referenced object
-    describes an initial conversion state; otherwise, it returns zero.
-    7.28.6.3 Restartable multibyte/wide character conversion functions
-1   These functions differ from the corresponding multibyte character functions of 7.22.7
-    (mblen, mbtowc, and wctomb) in that they have an extra parameter, ps, of type
-    pointer to mbstate_t that points to an object that can completely describe the current
-    conversion state of the associated multibyte character sequence. If ps is a null pointer,
-    each function uses its own internal mbstate_t object instead, which is initialized at
-    program startup to the initial conversion state; the functions are not required to avoid data
-    races in this case. The implementation behaves as if no library function calls these
-    functions with a null pointer for ps.
-2   Also unlike their corresponding functions, the return value does not represent whether the
-    encoding is state-dependent.
-    7.28.6.3.1 The mbrlen function
-    Synopsis
-1          #include <wchar.h>
-           size_t mbrlen(const char * restrict s,
-                size_t n,
-                mbstate_t * restrict ps);
-    Description
-2   The mbrlen function is equivalent to the call:
-           mbrtowc(NULL, s, n, ps != NULL ? ps : &internal)
-    where internal is the mbstate_t object for the mbrlen function, except that the
-    expression designated by ps is evaluated only once.
-    Returns
-3   The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2),
-    or (size_t)(-1).
-    Forward references: the mbrtowc function (7.28.6.3.2).
-
-
-
-
-[page 438] (Contents)
-
-    7.28.6.3.2 The mbrtowc function
-    Synopsis
-1           #include <wchar.h>
-            size_t mbrtowc(wchar_t * restrict pwc,
-                 const char * restrict s,
-                 size_t n,
-                 mbstate_t * restrict ps);
-    Description
-2   If s is a null pointer, the mbrtowc function is equivalent to the call:
-                    mbrtowc(NULL, "", 1, ps)
-    In this case, the values of the parameters pwc and n are ignored.
-3   If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with
-    the byte pointed to by s to determine the number of bytes needed to complete the next
-    multibyte character (including any shift sequences). If the function determines that the
-    next multibyte character is complete and valid, it determines the value of the
-    corresponding wide character and then, if pwc is not a null pointer, stores that value in
-    the object pointed to by pwc. If the corresponding wide character is the null wide
-    character, the resulting state described is the initial conversion state.
-    Returns
-4   The mbrtowc function returns the first of the following that applies (given the current
-    conversion state):
-    0                     if the next n or fewer bytes complete the multibyte character that
-                          corresponds to the null wide character (which is the value stored).
-    between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte
-                       character (which is the value stored); the value returned is the number
-                       of bytes that complete the multibyte character.
-    (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid)
-                 multibyte character, and all n bytes have been processed (no value is
-                 stored).332)
-    (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes
-                 do not contribute to a complete and valid multibyte character (no
-                 value is stored); the value of the macro EILSEQ is stored in errno,
-                 and the conversion state is unspecified.
-
-    332) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a
-         sequence of redundant shift sequences (for implementations with state-dependent encodings).
-
-[page 439] (Contents)
-
-    7.28.6.3.3 The wcrtomb function
-    Synopsis
-1           #include <wchar.h>
-            size_t wcrtomb(char * restrict s,
-                 wchar_t wc,
-                 mbstate_t * restrict ps);
-    Description
-2   If s is a null pointer, the wcrtomb function is equivalent to the call
-                    wcrtomb(buf, L'\0', ps)
-    where buf is an internal buffer.
-3   If s is not a null pointer, the wcrtomb function determines the number of bytes needed
-    to represent the multibyte character that corresponds to the wide character given by wc
-    (including any shift sequences), and stores the multibyte character representation in the
-    array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If
-    wc is a null wide character, a null byte is stored, preceded by any shift sequence needed
-    to restore the initial shift state; the resulting state described is the initial conversion state.
-    Returns
-4   The wcrtomb function returns the number of bytes stored in the array object (including
-    any shift sequences). When wc is not a valid wide character, an encoding error occurs:
-    the function stores the value of the macro EILSEQ in errno and returns
-    (size_t)(-1); the conversion state is unspecified.
-    7.28.6.4 Restartable multibyte/wide string conversion functions
-1   These functions differ from the corresponding multibyte string functions of 7.22.8
-    (mbstowcs and wcstombs) in that they have an extra parameter, ps, of type pointer to
-    mbstate_t that points to an object that can completely describe the current conversion
-    state of the associated multibyte character sequence. If ps is a null pointer, each function
-    uses its own internal mbstate_t object instead, which is initialized at program startup
-    to the initial conversion state; the functions are not required to avoid data races in this
-    case. The implementation behaves as if no library function calls these functions with a
-    null pointer for ps.
-2   Also unlike their corresponding functions, the conversion source parameter, src, has a
-    pointer-to-pointer type. When the function is storing the results of conversions (that is,
-    when dst is not a null pointer), the pointer object pointed to by this parameter is updated
-    to reflect the amount of the source processed by that invocation.
-
-
-
-
-[page 440] (Contents)
-
-    7.28.6.4.1 The mbsrtowcs function
-    Synopsis
-1            #include <wchar.h>
-             size_t mbsrtowcs(wchar_t * restrict dst,
-                  const char ** restrict src,
-                  size_t len,
-                  mbstate_t * restrict ps);
-    Description
-2   The mbsrtowcs function converts a sequence of multibyte characters that begins in the
-    conversion state described by the object pointed to by ps, from the array indirectly
-    pointed to by src into a sequence of corresponding wide characters. If dst is not a null
-    pointer, the converted characters are stored into the array pointed to by dst. Conversion
-    continues up to and including a terminating null character, which is also stored.
-    Conversion stops earlier in two cases: when a sequence of bytes is encountered that does
-    not form a valid multibyte character, or (if dst is not a null pointer) when len wide
-    characters have been stored into the array pointed to by dst.333) Each conversion takes
-    place as if by a call to the mbrtowc function.
-3   If dst is not a null pointer, the pointer object pointed to by src is assigned either a null
-    pointer (if conversion stopped due to reaching a terminating null character) or the address
-    just past the last multibyte character converted (if any). If conversion stopped due to
-    reaching a terminating null character and if dst is not a null pointer, the resulting state
-    described is the initial conversion state.
-    Returns
-4   If the input conversion encounters a sequence of bytes that do not form a valid multibyte
-    character, an encoding error occurs: the mbsrtowcs function stores the value of the
-    macro EILSEQ in errno and returns (size_t)(-1); the conversion state is
-    unspecified. Otherwise, it returns the number of multibyte characters successfully
-    converted, not including the terminating null character (if any).
-
-
-
-
-    333) Thus, the value of len is ignored if dst is a null pointer.
-
-[page 441] (Contents)
-
-    7.28.6.4.2 The wcsrtombs function
-    Synopsis
-1           #include <wchar.h>
-            size_t wcsrtombs(char * restrict dst,
-                 const wchar_t ** restrict src,
-                 size_t len,
-                 mbstate_t * restrict ps);
-    Description
-2   The wcsrtombs function converts a sequence of wide characters from the array
-    indirectly pointed to by src into a sequence of corresponding multibyte characters that
-    begins in the conversion state described by the object pointed to by ps. If dst is not a
-    null pointer, the converted characters are then stored into the array pointed to by dst.
-    Conversion continues up to and including a terminating null wide character, which is also
-    stored. Conversion stops earlier in two cases: when a wide character is reached that does
-    not correspond to a valid multibyte character, or (if dst is not a null pointer) when the
-    next multibyte character would exceed the limit of len total bytes to be stored into the
-    array pointed to by dst. Each conversion takes place as if by a call to the wcrtomb
-    function.334)
-3   If dst is not a null pointer, the pointer object pointed to by src is assigned either a null
-    pointer (if conversion stopped due to reaching a terminating null wide character) or the
-    address just past the last wide character converted (if any). If conversion stopped due to
-    reaching a terminating null wide character, the resulting state described is the initial
-    conversion state.
-    Returns
-4   If conversion stops because a wide character is reached that does not correspond to a
-    valid multibyte character, an encoding error occurs: the wcsrtombs function stores the
-    value of the macro EILSEQ in errno and returns (size_t)(-1); the conversion
-    state is unspecified. Otherwise, it returns the number of bytes in the resulting multibyte
-    character sequence, not including the terminating null character (if any).
-
-
-
-
-    334) If conversion stops because a terminating null wide character has been reached, the bytes stored
-         include those necessary to reach the initial shift state immediately before the null byte.
-
-[page 442] (Contents)
-
-    7.29 Wide character classification and mapping utilities <wctype.h>
-    7.29.1 Introduction
-1   The header <wctype.h> defines one macro, and declares three data types and many
-    functions.335)
-2   The types declared are
-              wint_t
-    described in 7.28.1;
-              wctrans_t
-    which is a scalar type that can hold values which represent locale-specific character
-    mappings; and
-              wctype_t
-    which is a scalar type that can hold values which represent locale-specific character
-    classifications.
-3   The macro defined is WEOF (described in 7.28.1).
-4   The functions declared are grouped as follows:
-    -- Functions that provide wide character classification;
-    -- Extensible functions that provide wide character classification;
-    -- Functions that provide wide character case mapping;
-    -- Extensible functions that provide wide character mapping.
-5   For all functions described in this subclause that accept an argument of type wint_t, the
-    value shall be representable as a wchar_t or shall equal the value of the macro WEOF. If
-    this argument has any other value, the behavior is undefined.
-6   The behavior of these functions is affected by the LC_CTYPE category of the current
-    locale.
-
-
-
-
-    335) See ''future library directions'' (7.30.13).
-
-[page 443] (Contents)
-
-    7.29.2 Wide character classification utilities
-1   The header <wctype.h> declares several functions useful for classifying wide
-    characters.
-2   The term printing wide character refers to a member of a locale-specific set of wide
-    characters, each of which occupies at least one printing position on a display device. The
-    term control wide character refers to a member of a locale-specific set of wide characters
-    that are not printing wide characters.
-    7.29.2.1 Wide character classification functions
-1   The functions in this subclause return nonzero (true) if and only if the value of the
-    argument wc conforms to that in the description of the function.
-2   Each of the following functions returns true for each wide character that corresponds (as
-    if by a call to the wctob function) to a single-byte character for which the corresponding
-    character classification function from 7.4.1 returns true, except that the iswgraph and
-    iswpunct functions may differ with respect to wide characters other than L' ' that are
-    both printing and white-space wide characters.336)
-    Forward references: the wctob function (7.28.6.1.2).
-    7.29.2.1.1 The iswalnum function
-    Synopsis
-1           #include <wctype.h>
-            int iswalnum(wint_t wc);
-    Description
-2   The iswalnum function tests for any wide character for which iswalpha or
-    iswdigit is true.
-    7.29.2.1.2 The iswalpha function
-    Synopsis
-1           #include <wctype.h>
-            int iswalpha(wint_t wc);
-    Description
-2   The iswalpha function tests for any wide character for which iswupper or
-    iswlower is true, or any wide character that is one of a locale-specific set of alphabetic
-
-    336) For example, if the expression isalpha(wctob(wc)) evaluates to true, then the call
-         iswalpha(wc) also returns true. But, if the expression isgraph(wctob(wc)) evaluates to true
-         (which cannot occur for wc == L' ' of course), then either iswgraph(wc) or iswprint(wc)
-         && iswspace(wc) is true, but not both.
-
-[page 444] (Contents)
-
-    wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace
-    is true.337)
-    7.29.2.1.3 The iswblank function
-    Synopsis
-1           #include <wctype.h>
-            int iswblank(wint_t wc);
-    Description
-2   The iswblank function tests for any wide character that is a standard blank wide
-    character or is one of a locale-specific set of wide characters for which iswspace is true
-    and that is used to separate words within a line of text. The standard blank wide
-    characters are the following: space (L' '), and horizontal tab (L'\t'). In the "C"
-    locale, iswblank returns true only for the standard blank characters.
-    7.29.2.1.4 The iswcntrl function
-    Synopsis
-1           #include <wctype.h>
-            int iswcntrl(wint_t wc);
-    Description
-2   The iswcntrl function tests for any control wide character.
-    7.29.2.1.5 The iswdigit function
-    Synopsis
-1           #include <wctype.h>
-            int iswdigit(wint_t wc);
-    Description
-2   The iswdigit function tests for any wide character that corresponds to a decimal-digit
-    character (as defined in 5.2.1).
-    7.29.2.1.6 The iswgraph function
-    Synopsis
-1           #include <wctype.h>
-            int iswgraph(wint_t wc);
-
-
-
-
-    337) The functions iswlower and iswupper test true or false separately for each of these additional
-         wide characters; all four combinations are possible.
-
-[page 445] (Contents)
-
-    Description
-2   The iswgraph function tests for any wide character for which iswprint is true and
-    iswspace is false.338)
-    7.29.2.1.7 The iswlower function
-    Synopsis
-1           #include <wctype.h>
-            int iswlower(wint_t wc);
-    Description
-2   The iswlower function tests for any wide character that corresponds to a lowercase
-    letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
-    iswdigit, iswpunct, or iswspace is true.
-    7.29.2.1.8 The iswprint function
-    Synopsis
-1           #include <wctype.h>
-            int iswprint(wint_t wc);
-    Description
-2   The iswprint function tests for any printing wide character.
-    7.29.2.1.9 The iswpunct function
-    Synopsis
-1           #include <wctype.h>
-            int iswpunct(wint_t wc);
-    Description
-2   The iswpunct function tests for any printing wide character that is one of a locale-
-    specific set of punctuation wide characters for which neither iswspace nor iswalnum
-    is true.338)
-    7.29.2.1.10 The iswspace function
-    Synopsis
-1           #include <wctype.h>
-            int iswspace(wint_t wc);
-
-
-
-    338) Note that the behavior of the iswgraph and iswpunct functions may differ from their
-         corresponding functions in 7.4.1 with respect to printing, white-space, single-byte execution
-         characters other than ' '.
-
-[page 446] (Contents)
-
-    Description
-2   The iswspace function tests for any wide character that corresponds to a locale-specific
-    set of white-space wide characters for which none of iswalnum, iswgraph, or
-    iswpunct is true.
-    7.29.2.1.11 The iswupper function
-    Synopsis
-1           #include <wctype.h>
-            int iswupper(wint_t wc);
-    Description
-2   The iswupper function tests for any wide character that corresponds to an uppercase
-    letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
-    iswdigit, iswpunct, or iswspace is true.
-    7.29.2.1.12 The iswxdigit function
-    Synopsis
-1           #include <wctype.h>
-            int iswxdigit(wint_t wc);
-    Description
-2   The iswxdigit function tests for any wide character that corresponds to a
-    hexadecimal-digit character (as defined in 6.4.4.1).
-    7.29.2.2 Extensible wide character classification functions
-1   The functions wctype and iswctype provide extensible wide character classification
-    as well as testing equivalent to that performed by the functions described in the previous
-    subclause (7.29.2.1).
-    7.29.2.2.1 The iswctype function
-    Synopsis
-1           #include <wctype.h>
-            int iswctype(wint_t wc, wctype_t desc);
-    Description
-2   The iswctype function determines whether the wide character wc has the property
-    described by desc. The current setting of the LC_CTYPE category shall be the same as
-    during the call to wctype that returned the value desc.
-3   Each of the following expressions has a truth-value equivalent to the call to the wide
-    character classification function (7.29.2.1) in the comment that follows the expression:
-
-
-[page 447] (Contents)
-
-           iswctype(wc,       wctype("alnum"))              //   iswalnum(wc)
-           iswctype(wc,       wctype("alpha"))              //   iswalpha(wc)
-           iswctype(wc,       wctype("blank"))              //   iswblank(wc)
-           iswctype(wc,       wctype("cntrl"))              //   iswcntrl(wc)
-           iswctype(wc,       wctype("digit"))              //   iswdigit(wc)
-           iswctype(wc,       wctype("graph"))              //   iswgraph(wc)
-           iswctype(wc,       wctype("lower"))              //   iswlower(wc)
-           iswctype(wc,       wctype("print"))              //   iswprint(wc)
-           iswctype(wc,       wctype("punct"))              //   iswpunct(wc)
-           iswctype(wc,       wctype("space"))              //   iswspace(wc)
-           iswctype(wc,       wctype("upper"))              //   iswupper(wc)
-           iswctype(wc,       wctype("xdigit"))             //   iswxdigit(wc)
-    Returns
-4   The iswctype function returns nonzero (true) if and only if the value of the wide
-    character wc has the property described by desc.
-    Forward references: the wctype function (7.29.2.2.2).
-    7.29.2.2.2 The wctype function
-    Synopsis
-1          #include <wctype.h>
-           wctype_t wctype(const char *property);
-    Description
-2   The wctype function constructs a value with type wctype_t that describes a class of
-    wide characters identified by the string argument property.
-3   The strings listed in the description of the iswctype function shall be valid in all
-    locales as property arguments to the wctype function.
-    Returns
-4   If property identifies a valid class of wide characters according to the LC_CTYPE
-    category of the current locale, the wctype function returns a nonzero value that is valid
-    as the second argument to the iswctype function; otherwise, it returns zero.
-
-
-
-
-[page 448] (Contents)
-
-    7.29.3 Wide character case mapping utilities
-1   The header <wctype.h> declares several functions useful for mapping wide characters.
-    7.29.3.1 Wide character case mapping functions
-    7.29.3.1.1 The towlower function
-    Synopsis
-1           #include <wctype.h>
-            wint_t towlower(wint_t wc);
-    Description
-2   The towlower function converts an uppercase letter to a corresponding lowercase letter.
-    Returns
-3   If the argument is a wide character for which iswupper is true and there are one or
-    more corresponding wide characters, as specified by the current locale, for which
-    iswlower is true, the towlower function returns one of the corresponding wide
-    characters (always the same one for any given locale); otherwise, the argument is
-    returned unchanged.
-    7.29.3.1.2 The towupper function
-    Synopsis
-1           #include <wctype.h>
-            wint_t towupper(wint_t wc);
-    Description
-2   The towupper function converts a lowercase letter to a corresponding uppercase letter.
-    Returns
-3   If the argument is a wide character for which iswlower is true and there are one or
-    more corresponding wide characters, as specified by the current locale, for which
-    iswupper is true, the towupper function returns one of the corresponding wide
-    characters (always the same one for any given locale); otherwise, the argument is
-    returned unchanged.
-    7.29.3.2 Extensible wide character case mapping functions
-1   The functions wctrans and towctrans provide extensible wide character mapping as
-    well as case mapping equivalent to that performed by the functions described in the
-    previous subclause (7.29.3.1).
-
-
-
-
-[page 449] (Contents)
-
-    7.29.3.2.1 The towctrans function
-    Synopsis
-1          #include <wctype.h>
-           wint_t towctrans(wint_t wc, wctrans_t desc);
-    Description
-2   The towctrans function maps the wide character wc using the mapping described by
-    desc. The current setting of the LC_CTYPE category shall be the same as during the call
-    to wctrans that returned the value desc.
-3   Each of the following expressions behaves the same as the call to the wide character case
-    mapping function (7.29.3.1) in the comment that follows the expression:
-           towctrans(wc, wctrans("tolower"))                      // towlower(wc)
-           towctrans(wc, wctrans("toupper"))                      // towupper(wc)
-    Returns
-4   The towctrans function returns the mapped value of wc using the mapping described
-    by desc.
-    7.29.3.2.2 The wctrans function
-    Synopsis
-1          #include <wctype.h>
-           wctrans_t wctrans(const char *property);
-    Description
-2   The wctrans function constructs a value with type wctrans_t that describes a
-    mapping between wide characters identified by the string argument property.
-3   The strings listed in the description of the towctrans function shall be valid in all
-    locales as property arguments to the wctrans function.
-    Returns
-4   If property identifies a valid mapping of wide characters according to the LC_CTYPE
-    category of the current locale, the wctrans function returns a nonzero value that is valid
-    as the second argument to the towctrans function; otherwise, it returns zero.
-
-
-
-
-[page 450] (Contents)
-
-    7.30 Future library directions
-1   The following names are grouped under individual headers for convenience. All external
-    names described below are reserved no matter what headers are included by the program.
-    7.30.1 Complex arithmetic <complex.h>
-1   The function names
-         cerf                cexpm1              clog2
-         cerfc               clog10              clgamma
-         cexp2               clog1p              ctgamma
-    and the same names suffixed with f or l may be added to the declarations in the
-    <complex.h> header.
-    7.30.2 Character handling <ctype.h>
-1   Function names that begin with either is or to, and a lowercase letter may be added to
-    the declarations in the <ctype.h> header.
-    7.30.3 Errors <errno.h>
-1   Macros that begin with E and a digit or E and an uppercase letter may be added to the
-    declarations in the <errno.h> header.
-    7.30.4 Format conversion of integer types <inttypes.h>
-1   Macro names beginning with PRI or SCN followed by any lowercase letter or X may be
-    added to the macros defined in the <inttypes.h> header.
-    7.30.5 Localization <locale.h>
-1   Macros that begin with LC_ and an uppercase letter may be added to the definitions in
-    the <locale.h> header.
-    7.30.6 Signal handling <signal.h>
-1   Macros that begin with either SIG and an uppercase letter or SIG_ and an uppercase
-    letter may be added to the definitions in the <signal.h> header.
-    7.30.7 Boolean type and values <stdbool.h>
-1   The ability to undefine and perhaps then redefine the macros bool, true, and false is
-    an obsolescent feature.
-    7.30.8 Integer types <stdint.h>
-1   Typedef names beginning with int or uint and ending with _t may be added to the
-    types defined in the <stdint.h> header. Macro names beginning with INT or UINT
-    and ending with _MAX, _MIN, or _C may be added to the macros defined in the
-    <stdint.h> header.
-
-[page 451] (Contents)
-
-    7.30.9 Input/output <stdio.h>
-1   Lowercase letters may be added to the conversion specifiers and length modifiers in
-    fprintf and fscanf. Other characters may be used in extensions.
-2   The use of ungetc on a binary stream where the file position indicator is zero prior to
-    the call is an obsolescent feature.
-    7.30.10 General utilities <stdlib.h>
-1   Function names that begin with str and a lowercase letter may be added to the
-    declarations in the <stdlib.h> header.
-    7.30.11 String handling <string.h>
-1   Function names that begin with str, mem, or wcs and a lowercase letter may be added
-    to the declarations in the <string.h> header.
-    7.30.12 Extended multibyte and wide character utilities <wchar.h>
-1   Function names that begin with wcs and a lowercase letter may be added to the
-    declarations in the <wchar.h> header.
-2   Lowercase letters may be added to the conversion specifiers and length modifiers in
-    fwprintf and fwscanf. Other characters may be used in extensions.
-    7.30.13 Wide character classification and mapping utilities
-    <wctype.h>
-1   Function names that begin with is or to and a lowercase letter may be added to the
-    declarations in the <wctype.h> header.
-
-
-
-
-[page 452] (Contents)
-
-                                                   Annex A
-                                                 (informative)
-                                  Language syntax summary
-1   NOTE     The notation is described in 6.1.
-
-    A.1 Lexical grammar
-    A.1.1 Lexical elements
-    (6.4) token:
-                     keyword
-                     identifier
-                     constant
-                     string-literal
-                     punctuator
-    (6.4) preprocessing-token:
-                  header-name
-                  identifier
-                  pp-number
-                  character-constant
-                  string-literal
-                  punctuator
-                  each non-white-space character that cannot be one of the above
-
-
-
-
-[page 453] (Contents)
-
-A.1.2 Keywords
-(6.4.1) keyword: one of
-              alignof                     goto                  union
-              auto                        if                    unsigned
-              break                       inline                void
-              case                        int                   volatile
-              char                        long                  while
-              const                       register              _Alignas
-              continue                    restrict              _Atomic
-              default                     return                _Bool
-              do                          short                 _Complex
-              double                      signed                _Generic
-              else                        sizeof                _Imaginary
-              enum                        static                _Noreturn
-              extern                      struct                _Static_assert
-              float                       switch                _Thread_local
-              for                         typedef
-A.1.3 Identifiers
-(6.4.2.1) identifier:
-               identifier-nondigit
-               identifier identifier-nondigit
-               identifier digit
-(6.4.2.1) identifier-nondigit:
-               nondigit
-               universal-character-name
-               other implementation-defined characters
-(6.4.2.1) nondigit: one of
-              _ a b          c    d   e    f   g   h    i   j   k   l   m
-                   n o       p    q   r    s   t   u    v   w   x   y   z
-                   A B       C    D   E    F   G   H    I   J   K   L   M
-                   N O       P    Q   R    S   T   U    V   W   X   Y   Z
-(6.4.2.1) digit: one of
-               0 1 2         3    4   5    6   7   8    9
-
-
-
-
-[page 454] (Contents)
-
-A.1.4 Universal character names
-(6.4.3) universal-character-name:
-              \u hex-quad
-              \U hex-quad hex-quad
-(6.4.3) hex-quad:
-              hexadecimal-digit hexadecimal-digit
-                           hexadecimal-digit hexadecimal-digit
-A.1.5 Constants
-(6.4.4) constant:
-              integer-constant
-              floating-constant
-              enumeration-constant
-              character-constant
-(6.4.4.1) integer-constant:
-               decimal-constant integer-suffixopt
-               octal-constant integer-suffixopt
-               hexadecimal-constant integer-suffixopt
-(6.4.4.1) decimal-constant:
-              nonzero-digit
-              decimal-constant digit
-(6.4.4.1) octal-constant:
-               0
-               octal-constant octal-digit
-(6.4.4.1) hexadecimal-constant:
-              hexadecimal-prefix hexadecimal-digit
-              hexadecimal-constant hexadecimal-digit
-(6.4.4.1) hexadecimal-prefix: one of
-              0x 0X
-(6.4.4.1) nonzero-digit: one of
-              1 2 3 4 5              6      7   8   9
-(6.4.4.1) octal-digit: one of
-               0 1 2 3           4   5      6   7
-
-
-
-
-[page 455] (Contents)
-
-(6.4.4.1) hexadecimal-digit: one of
-              0 1 2 3 4 5                6    7    8   9
-              a b c d e f
-              A B C D E F
-(6.4.4.1) integer-suffix:
-               unsigned-suffix long-suffixopt
-               unsigned-suffix long-long-suffix
-               long-suffix unsigned-suffixopt
-               long-long-suffix unsigned-suffixopt
-(6.4.4.1) unsigned-suffix: one of
-               u U
-(6.4.4.1) long-suffix: one of
-               l L
-(6.4.4.1) long-long-suffix: one of
-               ll LL
-(6.4.4.2) floating-constant:
-               decimal-floating-constant
-               hexadecimal-floating-constant
-(6.4.4.2) decimal-floating-constant:
-              fractional-constant exponent-partopt floating-suffixopt
-              digit-sequence exponent-part floating-suffixopt
-(6.4.4.2) hexadecimal-floating-constant:
-              hexadecimal-prefix hexadecimal-fractional-constant
-                            binary-exponent-part floating-suffixopt
-              hexadecimal-prefix hexadecimal-digit-sequence
-                            binary-exponent-part floating-suffixopt
-(6.4.4.2) fractional-constant:
-               digit-sequenceopt . digit-sequence
-               digit-sequence .
-(6.4.4.2) exponent-part:
-              e signopt digit-sequence
-              E signopt digit-sequence
-(6.4.4.2) sign: one of
-               + -
-
-
-
-[page 456] (Contents)
-
-(6.4.4.2) digit-sequence:
-               digit
-               digit-sequence digit
-(6.4.4.2) hexadecimal-fractional-constant:
-              hexadecimal-digit-sequenceopt .
-                             hexadecimal-digit-sequence
-              hexadecimal-digit-sequence .
-(6.4.4.2) binary-exponent-part:
-               p signopt digit-sequence
-               P signopt digit-sequence
-(6.4.4.2) hexadecimal-digit-sequence:
-              hexadecimal-digit
-              hexadecimal-digit-sequence hexadecimal-digit
-(6.4.4.2) floating-suffix: one of
-               f l F L
-(6.4.4.3) enumeration-constant:
-              identifier
-(6.4.4.4) character-constant:
-              ' c-char-sequence '
-              L' c-char-sequence '
-              u' c-char-sequence '
-              U' c-char-sequence '
-(6.4.4.4) c-char-sequence:
-               c-char
-               c-char-sequence c-char
-(6.4.4.4) c-char:
-               any member of the source character set except
-                            the single-quote ', backslash \, or new-line character
-               escape-sequence
-(6.4.4.4) escape-sequence:
-              simple-escape-sequence
-              octal-escape-sequence
-              hexadecimal-escape-sequence
-              universal-character-name
-
-
-
-
-[page 457] (Contents)
-
-(6.4.4.4) simple-escape-sequence: one of
-              \' \" \? \\
-              \a \b \f \n \r \t                   \v
-(6.4.4.4) octal-escape-sequence:
-               \ octal-digit
-               \ octal-digit octal-digit
-               \ octal-digit octal-digit octal-digit
-(6.4.4.4) hexadecimal-escape-sequence:
-              \x hexadecimal-digit
-              hexadecimal-escape-sequence hexadecimal-digit
-A.1.6 String literals
-(6.4.5) string-literal:
-               encoding-prefixopt " s-char-sequenceopt "
-(6.4.5) encoding-prefix:
-              u8
-              u
-              U
-              L
-(6.4.5) s-char-sequence:
-               s-char
-               s-char-sequence s-char
-(6.4.5) s-char:
-               any member of the source character set except
-                            the double-quote ", backslash \, or new-line character
-               escape-sequence
-A.1.7 Punctuators
-(6.4.6) punctuator: one of
-              [ ] ( ) { } . ->
-              ++ -- & * + - ~ !
-              / % << >> < > <= >=                      ==    !=    ^    |   &&   ||
-              ? : ; ...
-              = *= /= %= += -= <<=                     >>=    &=       ^=   |=
-              , # ##
-              <: :> <% %> %: %:%:
-
-
-
-
-[page 458] (Contents)
-
-A.1.8 Header names
-(6.4.7) header-name:
-              < h-char-sequence >
-              " q-char-sequence "
-(6.4.7) h-char-sequence:
-              h-char
-              h-char-sequence h-char
-(6.4.7) h-char:
-              any member of the source character set except
-                           the new-line character and >
-(6.4.7) q-char-sequence:
-              q-char
-              q-char-sequence q-char
-(6.4.7) q-char:
-              any member of the source character set except
-                           the new-line character and "
-A.1.9 Preprocessing numbers
-(6.4.8) pp-number:
-              digit
-              . digit
-              pp-number   digit
-              pp-number   identifier-nondigit
-              pp-number   e sign
-              pp-number   E sign
-              pp-number   p sign
-              pp-number   P sign
-              pp-number   .
-
-
-
-
-[page 459] (Contents)
-
-A.2 Phrase structure grammar
-A.2.1 Expressions
-(6.5.1) primary-expression:
-              identifier
-              constant
-              string-literal
-              ( expression )
-              generic-selection
-(6.5.1.1) generic-selection:
-              _Generic ( assignment-expression , generic-assoc-list )
-(6.5.1.1) generic-assoc-list:
-              generic-association
-              generic-assoc-list , generic-association
-(6.5.1.1) generic-association:
-              type-name : assignment-expression
-              default : assignment-expression
-(6.5.2) postfix-expression:
-              primary-expression
-              postfix-expression [ expression ]
-              postfix-expression ( argument-expression-listopt )
-              postfix-expression . identifier
-              postfix-expression -> identifier
-              postfix-expression ++
-              postfix-expression --
-              ( type-name ) { initializer-list }
-              ( type-name ) { initializer-list , }
-(6.5.2) argument-expression-list:
-             assignment-expression
-             argument-expression-list , assignment-expression
-(6.5.3) unary-expression:
-              postfix-expression
-              ++ unary-expression
-              -- unary-expression
-              unary-operator cast-expression
-              sizeof unary-expression
-              sizeof ( type-name )
-              alignof ( type-name )
-
-[page 460] (Contents)
-
-(6.5.3) unary-operator: one of
-              & * + - ~                !
-(6.5.4) cast-expression:
-               unary-expression
-               ( type-name ) cast-expression
-(6.5.5) multiplicative-expression:
-               cast-expression
-               multiplicative-expression * cast-expression
-               multiplicative-expression / cast-expression
-               multiplicative-expression % cast-expression
-(6.5.6) additive-expression:
-               multiplicative-expression
-               additive-expression + multiplicative-expression
-               additive-expression - multiplicative-expression
-(6.5.7) shift-expression:
-                additive-expression
-                shift-expression << additive-expression
-                shift-expression >> additive-expression
-(6.5.8) relational-expression:
-               shift-expression
-               relational-expression   <    shift-expression
-               relational-expression   >    shift-expression
-               relational-expression   <=   shift-expression
-               relational-expression   >=   shift-expression
-(6.5.9) equality-expression:
-               relational-expression
-               equality-expression == relational-expression
-               equality-expression != relational-expression
-(6.5.10) AND-expression:
-             equality-expression
-             AND-expression & equality-expression
-(6.5.11) exclusive-OR-expression:
-              AND-expression
-              exclusive-OR-expression ^ AND-expression
-
-
-
-
-[page 461] (Contents)
-
-(6.5.12) inclusive-OR-expression:
-               exclusive-OR-expression
-               inclusive-OR-expression | exclusive-OR-expression
-(6.5.13) logical-AND-expression:
-              inclusive-OR-expression
-              logical-AND-expression && inclusive-OR-expression
-(6.5.14) logical-OR-expression:
-              logical-AND-expression
-              logical-OR-expression || logical-AND-expression
-(6.5.15) conditional-expression:
-              logical-OR-expression
-              logical-OR-expression ? expression : conditional-expression
-(6.5.16) assignment-expression:
-              conditional-expression
-              unary-expression assignment-operator assignment-expression
-(6.5.16) assignment-operator: one of
-              = *= /= %= +=                -=    <<=    >>=      &=   ^=   |=
-(6.5.17) expression:
-              assignment-expression
-              expression , assignment-expression
-(6.6) constant-expression:
-              conditional-expression
-A.2.2 Declarations
-(6.7) declaration:
-               declaration-specifiers init-declarator-listopt ;
-               static_assert-declaration                                                 *
-(6.7) declaration-specifiers:
-               storage-class-specifier declaration-specifiersopt
-               type-specifier declaration-specifiersopt
-               type-qualifier declaration-specifiersopt
-               function-specifier declaration-specifiersopt
-               alignment-specifier declaration-specifiersopt
-(6.7) init-declarator-list:
-               init-declarator
-               init-declarator-list , init-declarator
-
-
-[page 462] (Contents)
-
-(6.7) init-declarator:
-               declarator
-               declarator = initializer
-(6.7.1) storage-class-specifier:
-              typedef
-              extern
-              static
-              _Thread_local
-              auto
-              register
-(6.7.2) type-specifier:
-               void
-               char
-               short
-               int
-               long
-               float
-               double
-               signed
-               unsigned
-               _Bool
-               _Complex
-               _Atomic ( type-name )
-               struct-or-union-specifier
-               enum-specifier
-               typedef-name
-(6.7.2.1) struct-or-union-specifier:
-               struct-or-union identifieropt { struct-declaration-list }
-               struct-or-union identifier
-(6.7.2.1) struct-or-union:
-               struct
-               union
-(6.7.2.1) struct-declaration-list:
-               struct-declaration
-               struct-declaration-list struct-declaration
-(6.7.2.1) struct-declaration:
-               specifier-qualifier-list struct-declarator-listopt ;
-               static_assert-declaration
-
-[page 463] (Contents)
-
-(6.7.2.1) specifier-qualifier-list:
-               type-specifier specifier-qualifier-listopt
-               type-qualifier specifier-qualifier-listopt
-(6.7.2.1) struct-declarator-list:
-               struct-declarator
-               struct-declarator-list , struct-declarator
-(6.7.2.1) struct-declarator:
-               declarator
-               declaratoropt : constant-expression
-(6.7.2.2) enum-specifier:
-              enum identifieropt { enumerator-list }
-              enum identifieropt { enumerator-list , }
-              enum identifier
-(6.7.2.2) enumerator-list:
-              enumerator
-              enumerator-list , enumerator
-(6.7.2.2) enumerator:
-              enumeration-constant
-              enumeration-constant = constant-expression
-(6.7.3) type-qualifier:
-              const
-              restrict
-              volatile
-              _Atomic
-(6.7.4) function-specifier:
-               inline
-               _Noreturn
-(6.7.5) alignment-specifier:
-              _Alignas ( type-name )
-              _Alignas ( constant-expression )
-(6.7.6) declarator:
-              pointeropt direct-declarator
-
-
-
-
-[page 464] (Contents)
-
-(6.7.6) direct-declarator:
-               identifier
-               ( declarator )
-               direct-declarator [ type-qualifier-listopt assignment-expressionopt ]
-               direct-declarator [ static type-qualifier-listopt assignment-expression ]
-               direct-declarator [ type-qualifier-list static assignment-expression ]
-               direct-declarator [ type-qualifier-listopt * ]
-               direct-declarator ( parameter-type-list )
-               direct-declarator ( identifier-listopt )
-(6.7.6) pointer:
-               * type-qualifier-listopt
-               * type-qualifier-listopt pointer
-(6.7.6) type-qualifier-list:
-              type-qualifier
-              type-qualifier-list type-qualifier
-(6.7.6) parameter-type-list:
-             parameter-list
-             parameter-list , ...
-(6.7.6) parameter-list:
-             parameter-declaration
-             parameter-list , parameter-declaration
-(6.7.6) parameter-declaration:
-             declaration-specifiers declarator
-             declaration-specifiers abstract-declaratoropt
-(6.7.6) identifier-list:
-               identifier
-               identifier-list , identifier
-(6.7.7) type-name:
-              specifier-qualifier-list abstract-declaratoropt
-(6.7.7) abstract-declarator:
-              pointer
-              pointeropt direct-abstract-declarator
-
-
-
-
-[page 465] (Contents)
-
-(6.7.7) direct-abstract-declarator:
-               ( abstract-declarator )
-               direct-abstract-declaratoropt [ type-qualifier-listopt
-                              assignment-expressionopt ]
-               direct-abstract-declaratoropt [ static type-qualifier-listopt
-                              assignment-expression ]
-               direct-abstract-declaratoropt [ type-qualifier-list static
-                              assignment-expression ]
-               direct-abstract-declaratoropt [ * ]
-               direct-abstract-declaratoropt ( parameter-type-listopt )
-(6.7.8) typedef-name:
-              identifier
-(6.7.9) initializer:
-                assignment-expression
-                { initializer-list }
-                { initializer-list , }
-(6.7.9) initializer-list:
-                designationopt initializer
-                initializer-list , designationopt initializer
-(6.7.9) designation:
-              designator-list =
-(6.7.9) designator-list:
-              designator
-              designator-list designator
-(6.7.9) designator:
-              [ constant-expression ]
-              . identifier
-(6.7.10) static_assert-declaration:
-               _Static_assert ( constant-expression , string-literal ) ;
-
-
-
-
-[page 466] (Contents)
-
-A.2.3 Statements
-(6.8) statement:
-              labeled-statement
-              compound-statement
-              expression-statement
-              selection-statement
-              iteration-statement
-              jump-statement
-(6.8.1) labeled-statement:
-               identifier : statement
-               case constant-expression : statement
-               default : statement
-(6.8.2) compound-statement:
-             { block-item-listopt }
-(6.8.2) block-item-list:
-               block-item
-               block-item-list block-item
-(6.8.2) block-item:
-               declaration
-               statement
-(6.8.3) expression-statement:
-              expressionopt ;
-(6.8.4) selection-statement:
-               if ( expression ) statement
-               if ( expression ) statement else statement
-               switch ( expression ) statement
-(6.8.5) iteration-statement:
-                while ( expression ) statement
-                do statement while ( expression ) ;
-                for ( expressionopt ; expressionopt ; expressionopt ) statement
-                for ( declaration expressionopt ; expressionopt ) statement
-(6.8.6) jump-statement:
-              goto identifier ;
-              continue ;
-              break ;
-              return expressionopt ;
-
-[page 467] (Contents)
-
-A.2.4 External definitions
-(6.9) translation-unit:
-               external-declaration
-               translation-unit external-declaration
-(6.9) external-declaration:
-               function-definition
-               declaration
-(6.9.1) function-definition:
-               declaration-specifiers declarator declaration-listopt compound-statement
-(6.9.1) declaration-list:
-              declaration
-              declaration-list declaration
-A.3 Preprocessing directives
-(6.10) preprocessing-file:
-              groupopt
-(6.10) group:
-                group-part
-                group group-part
-(6.10) group-part:
-              if-section
-              control-line
-              text-line
-              # non-directive
-(6.10) if-section:
-                if-group elif-groupsopt else-groupopt endif-line
-(6.10) if-group:
-               # if     constant-expression new-line groupopt
-               # ifdef identifier new-line groupopt
-               # ifndef identifier new-line groupopt
-(6.10) elif-groups:
-               elif-group
-               elif-groups elif-group
-(6.10) elif-group:
-               # elif        constant-expression new-line groupopt
-
-
-[page 468] (Contents)
-
-(6.10) else-group:
-               # else        new-line groupopt
-(6.10) endif-line:
-               # endif       new-line
-(6.10) control-line:
-              # include pp-tokens new-line
-              # define identifier replacement-list new-line
-              # define identifier lparen identifier-listopt )
-                                              replacement-list new-line
-              # define identifier lparen ... ) replacement-list new-line
-              # define identifier lparen identifier-list , ... )
-                                              replacement-list new-line
-              # undef   identifier new-line
-              # line    pp-tokens new-line
-              # error   pp-tokensopt new-line
-              # pragma pp-tokensopt new-line
-              #         new-line
-(6.10) text-line:
-               pp-tokensopt new-line
-(6.10) non-directive:
-              pp-tokens new-line
-(6.10) lparen:
-                 a ( character not immediately preceded by white-space
-(6.10) replacement-list:
-              pp-tokensopt
-(6.10) pp-tokens:
-              preprocessing-token
-              pp-tokens preprocessing-token
-(6.10) new-line:
-              the new-line character
-
-
-
-
-[page 469] (Contents)
-
-                              Annex B
-                            (informative)
-                         Library summary
-B.1 Diagnostics <assert.h>
-      NDEBUG
-      static_assert
-      void assert(scalar expression);
-B.2 Complex <complex.h>
-      __STDC_NO_COMPLEX__            imaginary
-      complex                          _Imaginary_I
-      _Complex_I                       I
-      #pragma STDC CX_LIMITED_RANGE on-off-switch
-      double complex cacos(double complex z);
-      float complex cacosf(float complex z);
-      long double complex cacosl(long double complex z);
-      double complex casin(double complex z);
-      float complex casinf(float complex z);
-      long double complex casinl(long double complex z);
-      double complex catan(double complex z);
-      float complex catanf(float complex z);
-      long double complex catanl(long double complex z);
-      double complex ccos(double complex z);
-      float complex ccosf(float complex z);
-      long double complex ccosl(long double complex z);
-      double complex csin(double complex z);
-      float complex csinf(float complex z);
-      long double complex csinl(long double complex z);
-      double complex ctan(double complex z);
-      float complex ctanf(float complex z);
-      long double complex ctanl(long double complex z);
-      double complex cacosh(double complex z);
-      float complex cacoshf(float complex z);
-      long double complex cacoshl(long double complex z);
-      double complex casinh(double complex z);
-      float complex casinhf(float complex z);
-      long double complex casinhl(long double complex z);
-
-[page 470] (Contents)
-
-        double complex catanh(double complex z);
-        float complex catanhf(float complex z);
-        long double complex catanhl(long double complex z);
-        double complex ccosh(double complex z);
-        float complex ccoshf(float complex z);
-        long double complex ccoshl(long double complex z);
-        double complex csinh(double complex z);
-        float complex csinhf(float complex z);
-        long double complex csinhl(long double complex z);
-        double complex ctanh(double complex z);
-        float complex ctanhf(float complex z);
-        long double complex ctanhl(long double complex z);
-        double complex cexp(double complex z);
-        float complex cexpf(float complex z);
-        long double complex cexpl(long double complex z);
-        double complex clog(double complex z);
-        float complex clogf(float complex z);
-        long double complex clogl(long double complex z);
-        double cabs(double complex z);
-        float cabsf(float complex z);
-        long double cabsl(long double complex z);
-        double complex cpow(double complex x, double complex y);
-        float complex cpowf(float complex x, float complex y);
-        long double complex cpowl(long double complex x,
-             long double complex y);
-        double complex csqrt(double complex z);
-        float complex csqrtf(float complex z);
-        long double complex csqrtl(long double complex z);
-        double carg(double complex z);
-        float cargf(float complex z);
-        long double cargl(long double complex z);
-        double cimag(double complex z);
-        float cimagf(float complex z);
-        long double cimagl(long double complex z);
-        double complex CMPLX(double x, double y);
-        float complex CMPLXF(float x, float y);
-        long double complex CMPLXL(long double x, long double y);
-        double complex conj(double complex z);
-        float complex conjf(float complex z);
-        long double complex conjl(long double complex z);
-        double complex cproj(double complex z);
-
-[page 471] (Contents)
-
-      float complex cprojf(float complex z);
-      long double complex cprojl(long double complex z);
-      double creal(double complex z);
-      float crealf(float complex z);
-      long double creall(long double complex z);
-B.3 Character handling <ctype.h>
-      int   isalnum(int c);
-      int   isalpha(int c);
-      int   isblank(int c);
-      int   iscntrl(int c);
-      int   isdigit(int c);
-      int   isgraph(int c);
-      int   islower(int c);
-      int   isprint(int c);
-      int   ispunct(int c);
-      int   isspace(int c);
-      int   isupper(int c);
-      int   isxdigit(int c);
-      int   tolower(int c);
-      int   toupper(int c);
-B.4 Errors <errno.h>
-      EDOM            EILSEQ            ERANGE           errno
-      __STDC_WANT_LIB_EXT1__
-      errno_t
-B.5 Floating-point environment <fenv.h>
-      fenv_t                FE_OVERFLOW              FE_TOWARDZERO
-      fexcept_t             FE_UNDERFLOW             FE_UPWARD
-      FE_DIVBYZERO          FE_ALL_EXCEPT            FE_DFL_ENV
-      FE_INEXACT            FE_DOWNWARD
-      FE_INVALID            FE_TONEAREST
-      #pragma STDC FENV_ACCESS on-off-switch
-      int feclearexcept(int excepts);
-      int fegetexceptflag(fexcept_t *flagp, int excepts);
-      int feraiseexcept(int excepts);
-      int fesetexceptflag(const fexcept_t *flagp,
-           int excepts);
-      int fetestexcept(int excepts);
-
-[page 472] (Contents)
-
-        int   fegetround(void);
-        int   fesetround(int round);
-        int   fegetenv(fenv_t *envp);
-        int   feholdexcept(fenv_t *envp);
-        int   fesetenv(const fenv_t *envp);
-        int   feupdateenv(const fenv_t *envp);
-B.6 Characteristics of floating types <float.h>
-        FLT_ROUNDS            DBL_DIG                  FLT_MAX
-        FLT_EVAL_METHOD       LDBL_DIG                 DBL_MAX
-        FLT_HAS_SUBNORM       FLT_MIN_EXP              LDBL_MAX
-        DBL_HAS_SUBNORM       DBL_MIN_EXP              FLT_EPSILON
-        LDBL_HAS_SUBNORM      LDBL_MIN_EXP             DBL_EPSILON
-        FLT_RADIX             FLT_MIN_10_EXP           LDBL_EPSILON
-        FLT_MANT_DIG          DBL_MIN_10_EXP           FLT_MIN
-        DBL_MANT_DIG          LDBL_MIN_10_EXP          DBL_MIN
-        LDBL_MANT_DIG         FLT_MAX_EXP              LDBL_MIN
-        FLT_DECIMAL_DIG       DBL_MAX_EXP              FLT_TRUE_MIN
-        DBL_DECIMAL_DIG       LDBL_MAX_EXP             DBL_TRUE_MIN
-        LDBL_DECIMAL_DIG      FLT_MAX_10_EXP           LDBL_TRUE_MIN
-        DECIMAL_DIG           DBL_MAX_10_EXP
-        FLT_DIG               LDBL_MAX_10_EXP
-B.7 Format conversion of integer types <inttypes.h>
-        imaxdiv_t
-        PRIdN       PRIdLEASTN       PRIdFASTN         PRIdMAX     PRIdPTR
-        PRIiN       PRIiLEASTN       PRIiFASTN         PRIiMAX     PRIiPTR
-        PRIoN       PRIoLEASTN       PRIoFASTN         PRIoMAX     PRIoPTR
-        PRIuN       PRIuLEASTN       PRIuFASTN         PRIuMAX     PRIuPTR
-        PRIxN       PRIxLEASTN       PRIxFASTN         PRIxMAX     PRIxPTR
-        PRIXN       PRIXLEASTN       PRIXFASTN         PRIXMAX     PRIXPTR
-        SCNdN       SCNdLEASTN       SCNdFASTN         SCNdMAX     SCNdPTR
-        SCNiN       SCNiLEASTN       SCNiFASTN         SCNiMAX     SCNiPTR
-        SCNoN       SCNoLEASTN       SCNoFASTN         SCNoMAX     SCNoPTR
-        SCNuN       SCNuLEASTN       SCNuFASTN         SCNuMAX     SCNuPTR
-        SCNxN       SCNxLEASTN       SCNxFASTN         SCNxMAX     SCNxPTR
-        intmax_t imaxabs(intmax_t j);
-        imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
-        intmax_t strtoimax(const char * restrict nptr,
-                char ** restrict endptr, int base);
-
-[page 473] (Contents)
-
-      uintmax_t strtoumax(const char * restrict nptr,
-              char ** restrict endptr, int base);
-      intmax_t wcstoimax(const wchar_t * restrict nptr,
-              wchar_t ** restrict endptr, int base);
-      uintmax_t wcstoumax(const wchar_t * restrict nptr,
-              wchar_t ** restrict endptr, int base);
-B.8 Alternative spellings <iso646.h>
-      and             bitor             not_eq           xor
-      and_eq          compl             or               xor_eq
-      bitand          not               or_eq
-B.9 Sizes of integer types <limits.h>
-      CHAR_BIT        CHAR_MAX          INT_MIN          ULONG_MAX
-      SCHAR_MIN       MB_LEN_MAX        INT_MAX          LLONG_MIN
-      SCHAR_MAX       SHRT_MIN          UINT_MAX         LLONG_MAX
-      UCHAR_MAX       SHRT_MAX          LONG_MIN         ULLONG_MAX
-      CHAR_MIN        USHRT_MAX         LONG_MAX
-B.10 Localization <locale.h>
-      struct lconv    LC_ALL            LC_CTYPE         LC_NUMERIC
-      NULL            LC_COLLATE        LC_MONETARY      LC_TIME
-      char *setlocale(int category, const char *locale);
-      struct lconv *localeconv(void);
-B.11 Mathematics <math.h>
-      float_t               FP_INFINITE              FP_FAST_FMAL
-      double_t              FP_NAN                   FP_ILOGB0
-      HUGE_VAL              FP_NORMAL                FP_ILOGBNAN
-      HUGE_VALF             FP_SUBNORMAL             MATH_ERRNO
-      HUGE_VALL             FP_ZERO                  MATH_ERREXCEPT
-      INFINITY              FP_FAST_FMA              math_errhandling
-      NAN                   FP_FAST_FMAF
-      #pragma STDC FP_CONTRACT on-off-switch
-      int fpclassify(real-floating x);
-      int isfinite(real-floating x);
-      int isinf(real-floating x);
-      int isnan(real-floating x);
-      int isnormal(real-floating x);
-      int signbit(real-floating x);
-[page 474] (Contents)
-
-        double acos(double x);
-        float acosf(float x);
-        long double acosl(long double x);
-        double asin(double x);
-        float asinf(float x);
-        long double asinl(long double x);
-        double atan(double x);
-        float atanf(float x);
-        long double atanl(long double x);
-        double atan2(double y, double x);
-        float atan2f(float y, float x);
-        long double atan2l(long double y, long double x);
-        double cos(double x);
-        float cosf(float x);
-        long double cosl(long double x);
-        double sin(double x);
-        float sinf(float x);
-        long double sinl(long double x);
-        double tan(double x);
-        float tanf(float x);
-        long double tanl(long double x);
-        double acosh(double x);
-        float acoshf(float x);
-        long double acoshl(long double x);
-        double asinh(double x);
-        float asinhf(float x);
-        long double asinhl(long double x);
-        double atanh(double x);
-        float atanhf(float x);
-        long double atanhl(long double x);
-        double cosh(double x);
-        float coshf(float x);
-        long double coshl(long double x);
-        double sinh(double x);
-        float sinhf(float x);
-        long double sinhl(long double x);
-        double tanh(double x);
-        float tanhf(float x);
-        long double tanhl(long double x);
-        double exp(double x);
-        float expf(float x);
-
-[page 475] (Contents)
-
-      long double expl(long double x);
-      double exp2(double x);
-      float exp2f(float x);
-      long double exp2l(long double x);
-      double expm1(double x);
-      float expm1f(float x);
-      long double expm1l(long double x);
-      double frexp(double value, int *exp);
-      float frexpf(float value, int *exp);
-      long double frexpl(long double value, int *exp);
-      int ilogb(double x);
-      int ilogbf(float x);
-      int ilogbl(long double x);
-      double ldexp(double x, int exp);
-      float ldexpf(float x, int exp);
-      long double ldexpl(long double x, int exp);
-      double log(double x);
-      float logf(float x);
-      long double logl(long double x);
-      double log10(double x);
-      float log10f(float x);
-      long double log10l(long double x);
-      double log1p(double x);
-      float log1pf(float x);
-      long double log1pl(long double x);
-      double log2(double x);
-      float log2f(float x);
-      long double log2l(long double x);
-      double logb(double x);
-      float logbf(float x);
-      long double logbl(long double x);
-      double modf(double value, double *iptr);
-      float modff(float value, float *iptr);
-      long double modfl(long double value, long double *iptr);
-      double scalbn(double x, int n);
-      float scalbnf(float x, int n);
-      long double scalbnl(long double x, int n);
-      double scalbln(double x, long int n);
-      float scalblnf(float x, long int n);
-      long double scalblnl(long double x, long int n);
-      double cbrt(double x);
-
-[page 476] (Contents)
-
-        float cbrtf(float x);
-        long double cbrtl(long double x);
-        double fabs(double x);
-        float fabsf(float x);
-        long double fabsl(long double x);
-        double hypot(double x, double y);
-        float hypotf(float x, float y);
-        long double hypotl(long double x, long double y);
-        double pow(double x, double y);
-        float powf(float x, float y);
-        long double powl(long double x, long double y);
-        double sqrt(double x);
-        float sqrtf(float x);
-        long double sqrtl(long double x);
-        double erf(double x);
-        float erff(float x);
-        long double erfl(long double x);
-        double erfc(double x);
-        float erfcf(float x);
-        long double erfcl(long double x);
-        double lgamma(double x);
-        float lgammaf(float x);
-        long double lgammal(long double x);
-        double tgamma(double x);
-        float tgammaf(float x);
-        long double tgammal(long double x);
-        double ceil(double x);
-        float ceilf(float x);
-        long double ceill(long double x);
-        double floor(double x);
-        float floorf(float x);
-        long double floorl(long double x);
-        double nearbyint(double x);
-        float nearbyintf(float x);
-        long double nearbyintl(long double x);
-        double rint(double x);
-        float rintf(float x);
-        long double rintl(long double x);
-        long int lrint(double x);
-        long int lrintf(float x);
-        long int lrintl(long double x);
-
-[page 477] (Contents)
-
-      long long int llrint(double x);
-      long long int llrintf(float x);
-      long long int llrintl(long double x);
-      double round(double x);
-      float roundf(float x);
-      long double roundl(long double x);
-      long int lround(double x);
-      long int lroundf(float x);
-      long int lroundl(long double x);
-      long long int llround(double x);
-      long long int llroundf(float x);
-      long long int llroundl(long double x);
-      double trunc(double x);
-      float truncf(float x);
-      long double truncl(long double x);
-      double fmod(double x, double y);
-      float fmodf(float x, float y);
-      long double fmodl(long double x, long double y);
-      double remainder(double x, double y);
-      float remainderf(float x, float y);
-      long double remainderl(long double x, long double y);
-      double remquo(double x, double y, int *quo);
-      float remquof(float x, float y, int *quo);
-      long double remquol(long double x, long double y,
-           int *quo);
-      double copysign(double x, double y);
-      float copysignf(float x, float y);
-      long double copysignl(long double x, long double y);
-      double nan(const char *tagp);
-      float nanf(const char *tagp);
-      long double nanl(const char *tagp);
-      double nextafter(double x, double y);
-      float nextafterf(float x, float y);
-      long double nextafterl(long double x, long double y);
-      double nexttoward(double x, long double y);
-      float nexttowardf(float x, long double y);
-      long double nexttowardl(long double x, long double y);
-      double fdim(double x, double y);
-      float fdimf(float x, float y);
-      long double fdiml(long double x, long double y);
-      double fmax(double x, double y);
-
-[page 478] (Contents)
-
-        float fmaxf(float x, float y);
-        long double fmaxl(long double x, long double y);
-        double fmin(double x, double y);
-        float fminf(float x, float y);
-        long double fminl(long double x, long double y);
-        double fma(double x, double y, double z);
-        float fmaf(float x, float y, float z);
-        long double fmal(long double x, long double y,
-             long double z);
-        int isgreater(real-floating x, real-floating y);
-        int isgreaterequal(real-floating x, real-floating y);
-        int isless(real-floating x, real-floating y);
-        int islessequal(real-floating x, real-floating y);
-        int islessgreater(real-floating x, real-floating y);
-        int isunordered(real-floating x, real-floating y);
-B.12 Nonlocal jumps <setjmp.h>
-        jmp_buf
-        int setjmp(jmp_buf env);
-        _Noreturn void longjmp(jmp_buf env, int val);
-B.13 Signal handling <signal.h>
-        sig_atomic_t    SIG_IGN           SIGILL           SIGTERM
-        SIG_DFL         SIGABRT           SIGINT
-        SIG_ERR         SIGFPE            SIGSEGV
-        void (*signal(int sig, void (*func)(int)))(int);
-        int raise(int sig);
-
-
-
-
-[page 479] (Contents)
-
-B.14 Alignment <stdalign.h>
-      alignas
-      __alignas_is_defined
-B.15 Variable arguments <stdarg.h>
-      va_list
-      type va_arg(va_list ap, type);
-      void va_copy(va_list dest, va_list src);
-      void va_end(va_list ap);
-      void va_start(va_list ap, parmN);
-B.16 Atomics <stdatomic.h>
-      ATOMIC_CHAR_LOCK_FREE            atomic_uint
-      ATOMIC_CHAR16_T_LOCK_FREE        atomic_long
-      ATOMIC_CHAR32_T_LOCK_FREE        atomic_ulong
-      ATOMIC_WCHAR_T_LOCK_FREE         atomic_llong
-      ATOMIC_SHORT_LOCK_FREE           atomic_ullong
-      ATOMIC_INT_LOCK_FREE             atomic_char16_t
-      ATOMIC_LONG_LOCK_FREE            atomic_char32_t
-      ATOMIC_LLONG_LOCK_FREE           atomic_wchar_t
-      ATOMIC_ADDRESS_LOCK_FREE         atomic_int_least8_t
-      ATOMIC_FLAG_INIT                 atomic_uint_least8_t
-      memory_order                     atomic_int_least16_t
-      atomic_flag                      atomic_uint_least16_t
-      atomic_bool                      atomic_int_least32_t
-      atomic_address                   atomic_uint_least32_t
-      memory_order_relaxed             atomic_int_least64_t
-      memory_order_consume             atomic_uint_least64_t
-      memory_order_acquire             atomic_int_fast8_t
-      memory_order_release             atomic_uint_fast8_t
-      memory_order_acq_rel             atomic_int_fast16_t
-      memory_order_seq_cst             atomic_uint_fast16_t
-      atomic_char                      atomic_int_fast32_t
-      atomic_schar                     atomic_uint_fast32_t
-      atomic_uchar                     atomic_int_fast64_t
-      atomic_short                     atomic_uint_fast64_t
-      atomic_ushort                    atomic_intptr_t
-      atomic_int                       atomic_uintptr_t
-
-
-
-[page 480] (Contents)
-
-        atomic_size_t                   atomic_intmax_t
-        atomic_ptrdiff_t                atomic_uintmax_t
-        #define ATOMIC_VAR_INIT(C value)
-        void atomic_init(volatile A *obj, C value);
-        type kill_dependency(type y);
-        void atomic_thread_fence(memory_order order);
-        void atomic_signal_fence(memory_order order);
-        _Bool atomic_is_lock_free(atomic_type const volatile *obj);
-        void atomic_store(volatile A *object, C desired);
-        void atomic_store_explicit(volatile A *object,
-              C desired, memory_order order);
-        C atomic_load(volatile A *object);
-        C atomic_load_explicit(volatile A *object,
-              memory_order order);
-        C atomic_exchange(volatile A *object, C desired);
-        C atomic_exchange_explicit(volatile A *object,
-              C desired, memory_order order);
-        _Bool atomic_compare_exchange_strong(volatile A *object,
-              C *expected, C desired);
-        _Bool atomic_compare_exchange_strong_explicit(
-              volatile A *object, C *expected, C desired,
-              memory_order success, memory_order failure);
-        _Bool atomic_compare_exchange_weak(volatile A *object,
-              C *expected, C desired);
-        _Bool atomic_compare_exchange_weak_explicit(
-              volatile A *object, C *expected, C desired,
-              memory_order success, memory_order failure);
-        C atomic_fetch_key(volatile A *object, M operand);
-        C atomic_fetch_key_explicit(volatile A *object,
-              M operand, memory_order order);
-        bool atomic_flag_test_and_set(
-              volatile atomic_flag *object);
-        bool atomic_flag_test_and_set_explicit(
-              volatile atomic_flag *object, memory_order order);
-        void atomic_flag_clear(volatile atomic_flag *object);
-        void atomic_flag_clear_explicit(
-              volatile atomic_flag *object, memory_order order);
-
-
-
-
-[page 481] (Contents)
-
-B.17 Boolean type and values <stdbool.h>
-      bool
-      true
-      false
-      __bool_true_false_are_defined
-B.18 Common definitions <stddef.h>
-      ptrdiff_t       max_align_t       NULL
-      size_t          wchar_t
-      offsetof(type, member-designator)
-      __STDC_WANT_LIB_EXT1__
-      rsize_t
-B.19 Integer types <stdint.h>
-      intN_t                INT_LEASTN_MIN           PTRDIFF_MAX
-      uintN_t               INT_LEASTN_MAX           SIG_ATOMIC_MIN
-      int_leastN_t          UINT_LEASTN_MAX          SIG_ATOMIC_MAX
-      uint_leastN_t         INT_FASTN_MIN            SIZE_MAX
-      int_fastN_t           INT_FASTN_MAX            WCHAR_MIN
-      uint_fastN_t          UINT_FASTN_MAX           WCHAR_MAX
-      intptr_t              INTPTR_MIN               WINT_MIN
-      uintptr_t             INTPTR_MAX               WINT_MAX
-      intmax_t              UINTPTR_MAX              INTN_C(value)
-      uintmax_t             INTMAX_MIN               UINTN_C(value)
-      INTN_MIN              INTMAX_MAX               INTMAX_C(value)
-      INTN_MAX              UINTMAX_MAX              UINTMAX_C(value)
-      UINTN_MAX             PTRDIFF_MIN
-      __STDC_WANT_LIB_EXT1__
-      RSIZE_MAX
-
-
-
-
-[page 482] (Contents)
-
-B.20 Input/output <stdio.h>
-        size_t       _IOLBF            FILENAME_MAX     TMP_MAX
-        FILE         _IONBF            L_tmpnam         stderr
-        fpos_t       BUFSIZ            SEEK_CUR         stdin
-        NULL         EOF               SEEK_END         stdout
-        _IOFBF       FOPEN_MAX         SEEK_SET
-        int remove(const char *filename);
-        int rename(const char *old, const char *new);
-        FILE *tmpfile(void);
-        char *tmpnam(char *s);
-        int fclose(FILE *stream);
-        int fflush(FILE *stream);
-        FILE *fopen(const char * restrict filename,
-             const char * restrict mode);
-        FILE *freopen(const char * restrict filename,
-             const char * restrict mode,
-             FILE * restrict stream);
-        void setbuf(FILE * restrict stream,
-             char * restrict buf);
-        int setvbuf(FILE * restrict stream,
-             char * restrict buf,
-             int mode, size_t size);
-        int fprintf(FILE * restrict stream,
-             const char * restrict format, ...);
-        int fscanf(FILE * restrict stream,
-             const char * restrict format, ...);
-        int printf(const char * restrict format, ...);
-        int scanf(const char * restrict format, ...);
-        int snprintf(char * restrict s, size_t n,
-             const char * restrict format, ...);
-        int sprintf(char * restrict s,
-             const char * restrict format, ...);
-        int sscanf(const char * restrict s,
-             const char * restrict format, ...);
-        int vfprintf(FILE * restrict stream,
-             const char * restrict format, va_list arg);
-        int vfscanf(FILE * restrict stream,
-             const char * restrict format, va_list arg);
-        int vprintf(const char * restrict format, va_list arg);
-        int vscanf(const char * restrict format, va_list arg);
-
-[page 483] (Contents)
-
-      int vsnprintf(char * restrict s, size_t n,
-           const char * restrict format, va_list arg);
-      int vsprintf(char * restrict s,
-           const char * restrict format, va_list arg);
-      int vsscanf(const char * restrict s,
-           const char * restrict format, va_list arg);
-      int fgetc(FILE *stream);
-      char *fgets(char * restrict s, int n,
-           FILE * restrict stream);
-      int fputc(int c, FILE *stream);
-      int fputs(const char * restrict s,
-           FILE * restrict stream);
-      int getc(FILE *stream);
-      int getchar(void);
-      int putc(int c, FILE *stream);
-      int putchar(int c);
-      int puts(const char *s);
-      int ungetc(int c, FILE *stream);
-      size_t fread(void * restrict ptr,
-           size_t size, size_t nmemb,
-           FILE * restrict stream);
-      size_t fwrite(const void * restrict ptr,
-           size_t size, size_t nmemb,
-           FILE * restrict stream);
-      int fgetpos(FILE * restrict stream,
-           fpos_t * restrict pos);
-      int fseek(FILE *stream, long int offset, int whence);
-      int fsetpos(FILE *stream, const fpos_t *pos);
-      long int ftell(FILE *stream);
-      void rewind(FILE *stream);
-      void clearerr(FILE *stream);
-      int feof(FILE *stream);
-      int ferror(FILE *stream);
-      void perror(const char *s);
-      __STDC_WANT_LIB_EXT1__
-      L_tmpnam_s    TMP_MAX_S          errno_t          rsize_t
-      errno_t tmpfile_s(FILE * restrict * restrict streamptr);
-      errno_t tmpnam_s(char *s, rsize_t maxsize);
-
-
-
-[page 484] (Contents)
-
-        errno_t fopen_s(FILE * restrict * restrict streamptr,
-             const char * restrict filename,
-             const char * restrict mode);
-        errno_t freopen_s(FILE * restrict * restrict newstreamptr,
-             const char * restrict filename,
-             const char * restrict mode,
-             FILE * restrict stream);
-        int fprintf_s(FILE * restrict stream,
-             const char * restrict format, ...);
-        int fscanf_s(FILE * restrict stream,
-             const char * restrict format, ...);
-        int printf_s(const char * restrict format, ...);
-        int scanf_s(const char * restrict format, ...);
-        int snprintf_s(char * restrict s, rsize_t n,
-             const char * restrict format, ...);
-        int sprintf_s(char * restrict s, rsize_t n,
-             const char * restrict format, ...);
-        int sscanf_s(const char * restrict s,
-             const char * restrict format, ...);
-        int vfprintf_s(FILE * restrict stream,
-             const char * restrict format,
-             va_list arg);
-        int vfscanf_s(FILE * restrict stream,
-             const char * restrict format,
-             va_list arg);
-        int vprintf_s(const char * restrict format,
-             va_list arg);
-        int vscanf_s(const char * restrict format,
-             va_list arg);
-        int vsnprintf_s(char * restrict s, rsize_t n,
-             const char * restrict format,
-             va_list arg);
-        int vsprintf_s(char * restrict s, rsize_t n,
-             const char * restrict format,
-             va_list arg);
-        int vsscanf_s(const char * restrict s,
-             const char * restrict format,
-             va_list arg);
-        char *gets_s(char *s, rsize_t n);
-
-
-
-[page 485] (Contents)
-
-B.21 General utilities <stdlib.h>
-      size_t         ldiv_t            EXIT_FAILURE     MB_CUR_MAX
-      wchar_t        lldiv_t           EXIT_SUCCESS
-      div_t          NULL              RAND_MAX
-      double atof(const char *nptr);
-      int atoi(const char *nptr);
-      long int atol(const char *nptr);
-      long long int atoll(const char *nptr);
-      double strtod(const char * restrict nptr,
-           char ** restrict endptr);
-      float strtof(const char * restrict nptr,
-           char ** restrict endptr);
-      long double strtold(const char * restrict nptr,
-           char ** restrict endptr);
-      long int strtol(const char * restrict nptr,
-           char ** restrict endptr, int base);
-      long long int strtoll(const char * restrict nptr,
-           char ** restrict endptr, int base);
-      unsigned long int strtoul(
-           const char * restrict nptr,
-           char ** restrict endptr, int base);
-      unsigned long long int strtoull(
-           const char * restrict nptr,
-           char ** restrict endptr, int base);
-      int rand(void);
-      void srand(unsigned int seed);
-      void *aligned_alloc(size_t alignment, size_t size);
-      void *calloc(size_t nmemb, size_t size);
-      void free(void *ptr);
-      void *malloc(size_t size);
-      void *realloc(void *ptr, size_t size);
-      _Noreturn void abort(void);
-      int atexit(void (*func)(void));
-      int at_quick_exit(void (*func)(void));
-      _Noreturn void exit(int status);
-      _Noreturn void _Exit(int status);
-      char *getenv(const char *name);
-      _Noreturn void quick_exit(int status);
-      int system(const char *string);
-
-
-[page 486] (Contents)
-
-        void *bsearch(const void *key, const void *base,
-             size_t nmemb, size_t size,
-             int (*compar)(const void *, const void *));
-        void qsort(void *base, size_t nmemb, size_t size,
-             int (*compar)(const void *, const void *));
-        int abs(int j);
-        long int labs(long int j);
-        long long int llabs(long long int j);
-        div_t div(int numer, int denom);
-        ldiv_t ldiv(long int numer, long int denom);
-        lldiv_t lldiv(long long int numer,
-             long long int denom);
-        int mblen(const char *s, size_t n);
-        int mbtowc(wchar_t * restrict pwc,
-             const char * restrict s, size_t n);
-        int wctomb(char *s, wchar_t wchar);
-        size_t mbstowcs(wchar_t * restrict pwcs,
-             const char * restrict s, size_t n);
-        size_t wcstombs(char * restrict s,
-             const wchar_t * restrict pwcs, size_t n);
-        __STDC_WANT_LIB_EXT1__
-        errno_t
-        rsize_t
-        constraint_handler_t
-        constraint_handler_t set_constraint_handler_s(
-             constraint_handler_t handler);
-        void abort_handler_s(
-             const char * restrict msg,
-             void * restrict ptr,
-             errno_t error);
-        void ignore_handler_s(
-             const char * restrict msg,
-             void * restrict ptr,
-             errno_t error);
-        errno_t getenv_s(size_t * restrict len,
-                  char * restrict value, rsize_t maxsize,
-                  const char * restrict name);
-
-
-
-
-[page 487] (Contents)
-
-      void *bsearch_s(const void *key, const void *base,
-           rsize_t nmemb, rsize_t size,
-           int (*compar)(const void *k, const void *y,
-                           void *context),
-           void *context);
-      errno_t qsort_s(void *base, rsize_t nmemb, rsize_t size,
-           int (*compar)(const void *x, const void *y,
-                           void *context),
-           void *context);
-      errno_t wctomb_s(int * restrict status,
-           char * restrict s,
-           rsize_t smax,
-           wchar_t wc);
-      errno_t mbstowcs_s(size_t * restrict retval,
-           wchar_t * restrict dst, rsize_t dstmax,
-           const char * restrict src, rsize_t len);
-      errno_t wcstombs_s(size_t * restrict retval,
-           char * restrict dst, rsize_t dstmax,
-           const wchar_t * restrict src, rsize_t len);
-B.22 String handling <string.h>
-      size_t
-      NULL
-      void *memcpy(void * restrict s1,
-           const void * restrict s2, size_t n);
-      void *memmove(void *s1, const void *s2, size_t n);
-      char *strcpy(char * restrict s1,
-           const char * restrict s2);
-      char *strncpy(char * restrict s1,
-           const char * restrict s2, size_t n);
-      char *strcat(char * restrict s1,
-           const char * restrict s2);
-      char *strncat(char * restrict s1,
-           const char * restrict s2, size_t n);
-      int memcmp(const void *s1, const void *s2, size_t n);
-      int strcmp(const char *s1, const char *s2);
-      int strcoll(const char *s1, const char *s2);
-      int strncmp(const char *s1, const char *s2, size_t n);
-      size_t strxfrm(char * restrict s1,
-           const char * restrict s2, size_t n);
-      void *memchr(const void *s, int c, size_t n);
-[page 488] (Contents)
-
-        char *strchr(const char *s, int c);
-        size_t strcspn(const char *s1, const char *s2);
-        char *strpbrk(const char *s1, const char *s2);
-        char *strrchr(const char *s, int c);
-        size_t strspn(const char *s1, const char *s2);
-        char *strstr(const char *s1, const char *s2);
-        char *strtok(char * restrict s1,
-             const char * restrict s2);
-        void *memset(void *s, int c, size_t n);
-        char *strerror(int errnum);
-        size_t strlen(const char *s);
-        __STDC_WANT_LIB_EXT1__
-        errno_t
-        rsize_t
-        errno_t memcpy_s(void * restrict s1, rsize_t s1max,
-             const void * restrict s2, rsize_t n);
-        errno_t memmove_s(void *s1, rsize_t s1max,
-             const void *s2, rsize_t n);
-        errno_t strcpy_s(char * restrict s1,
-             rsize_t s1max,
-             const char * restrict s2);
-        errno_t strncpy_s(char * restrict s1,
-             rsize_t s1max,
-             const char * restrict s2,
-             rsize_t n);
-        errno_t strcat_s(char * restrict s1,
-             rsize_t s1max,
-             const char * restrict s2);
-        errno_t strncat_s(char * restrict s1,
-             rsize_t s1max,
-             const char * restrict s2,
-             rsize_t n);
-        char *strtok_s(char * restrict s1,
-             rsize_t * restrict s1max,
-             const char * restrict s2,
-             char ** restrict ptr);
-        errno_t memset_s(void *s, rsize_t smax, int c, rsize_t n)
-        errno_t strerror_s(char *s, rsize_t maxsize,
-             errno_t errnum);
-        size_t strerrorlen_s(errno_t errnum);
-
-[page 489] (Contents)
-
-      size_t strnlen_s(const char *s, size_t maxsize);
-B.23 Type-generic math <tgmath.h>
-      acos           sqrt              fmod             nextafter
-      asin           fabs              frexp            nexttoward
-      atan           atan2             hypot            remainder
-      acosh          cbrt              ilogb            remquo
-      asinh          ceil              ldexp            rint
-      atanh          copysign          lgamma           round
-      cos            erf               llrint           scalbn
-      sin            erfc              llround          scalbln
-      tan            exp2              log10            tgamma
-      cosh           expm1             log1p            trunc
-      sinh           fdim              log2             carg
-      tanh           floor             logb             cimag
-      exp            fma               lrint            conj
-      log            fmax              lround           cproj
-      pow            fmin              nearbyint        creal
-B.24 Threads <threads.h>
-      ONCE_FLAG_INIT                   mtx_plain
-      TSS_DTOR_ITERATIONS              mtx_recursive
-      cnd_t                            mtx_timed
-      thrd_t                           mtx_try
-      tss_t                            thrd_timeout
-      mtx_t                            thrd_success
-      tss_dtor_t                       thrd_busy
-      thrd_start_t                     thrd_error
-      once_flag                        thrd_nomem
-      xtime
-      void call_once(once_flag *flag, void (*func)(void));
-      int cnd_broadcast(cnd_t *cond);
-      void cnd_destroy(cnd_t *cond);
-      int cnd_init(cnd_t *cond);
-      int cnd_signal(cnd_t *cond);
-      int cnd_timedwait(cnd_t *cond, mtx_t *mtx,
-           const xtime *xt);
-      int cnd_wait(cnd_t *cond, mtx_t *mtx);
-      void mtx_destroy(mtx_t *mtx);
-      int mtx_init(mtx_t *mtx, int type);
-      int mtx_lock(mtx_t *mtx);
-[page 490] (Contents)
-
-        int mtx_timedlock(mtx_t *mtx, const xtime *xt);
-        int mtx_trylock(mtx_t *mtx);
-        int mtx_unlock(mtx_t *mtx);
-        int thrd_create(thrd_t *thr, thrd_start_t func,
-             void *arg);
-        thrd_t thrd_current(void);
-        int thrd_detach(thrd_t thr);
-        int thrd_equal(thrd_t thr0, thrd_t thr1);
-        void thrd_exit(int res);
-        int thrd_join(thrd_t thr, int *res);
-        void thrd_sleep(const xtime *xt);
-        void thrd_yield(void);
-        int tss_create(tss_t *key, tss_dtor_t dtor);
-        void tss_delete(tss_t key);
-        void *tss_get(tss_t key);
-        int tss_set(tss_t key, void *val);
-        int xtime_get(xtime *xt, int base);
-B.25 Date and time <time.h>
-        NULL                size_t                   time_t
-        CLOCKS_PER_SEC      clock_t                  struct tm
-        clock_t clock(void);
-        double difftime(time_t time1, time_t time0);
-        time_t mktime(struct tm *timeptr);
-        time_t time(time_t *timer);
-        char *asctime(const struct tm *timeptr);
-        char *ctime(const time_t *timer);
-        struct tm *gmtime(const time_t *timer);
-        struct tm *localtime(const time_t *timer);
-        size_t strftime(char * restrict s,
-             size_t maxsize,
-             const char * restrict format,
-             const struct tm * restrict timeptr);
-        __STDC_WANT_LIB_EXT1__
-        errno_t
-        rsize_t
-        errno_t asctime_s(char *s, rsize_t maxsize,
-             const struct tm *timeptr);
-
-
-
-[page 491] (Contents)
-
-      errno_t ctime_s(char *s, rsize_t maxsize,
-           const time_t *timer);
-      struct tm *gmtime_s(const time_t * restrict timer,
-           struct tm * restrict result);
-      struct tm *localtime_s(const time_t * restrict timer,
-           struct tm * restrict result);
-B.26 Unicode utilities <uchar.h>
-      mbstate_t      size_t            char16_t         char32_t
-      size_t mbrtoc16(char16_t * restrict pc16,
-           const char * restrict s, size_t n,
-           mbstate_t * restrict ps);
-      size_t c16rtomb(char * restrict s, char16_t c16,
-           mbstate_t * restrict ps);
-      size_t mbrtoc32(char32_t * restrict pc32,
-           const char * restrict s, size_t n,
-           mbstate_t * restrict ps);
-      size_t c32rtomb(char * restrict s, char32_t c32,
-           mbstate_t * restrict ps);
-B.27 Extended multibyte/wide character utilities <wchar.h>
-      wchar_t              wint_t                   WCHAR_MAX
-      size_t               struct tm                WCHAR_MIN
-      mbstate_t            NULL                     WEOF
-      int fwprintf(FILE * restrict stream,
-           const wchar_t * restrict format, ...);
-      int fwscanf(FILE * restrict stream,
-           const wchar_t * restrict format, ...);
-      int swprintf(wchar_t * restrict s, size_t n,
-           const wchar_t * restrict format, ...);
-      int swscanf(const wchar_t * restrict s,
-           const wchar_t * restrict format, ...);
-      int vfwprintf(FILE * restrict stream,
-           const wchar_t * restrict format, va_list arg);
-      int vfwscanf(FILE * restrict stream,
-           const wchar_t * restrict format, va_list arg);
-      int vswprintf(wchar_t * restrict s, size_t n,
-           const wchar_t * restrict format, va_list arg);
-
-
-
-[page 492] (Contents)
-
-        int vswscanf(const wchar_t * restrict s,
-             const wchar_t * restrict format, va_list arg);
-        int vwprintf(const wchar_t * restrict format,
-             va_list arg);
-        int vwscanf(const wchar_t * restrict format,
-             va_list arg);
-        int wprintf(const wchar_t * restrict format, ...);
-        int wscanf(const wchar_t * restrict format, ...);
-        wint_t fgetwc(FILE *stream);
-        wchar_t *fgetws(wchar_t * restrict s, int n,
-             FILE * restrict stream);
-        wint_t fputwc(wchar_t c, FILE *stream);
-        int fputws(const wchar_t * restrict s,
-             FILE * restrict stream);
-        int fwide(FILE *stream, int mode);
-        wint_t getwc(FILE *stream);
-        wint_t getwchar(void);
-        wint_t putwc(wchar_t c, FILE *stream);
-        wint_t putwchar(wchar_t c);
-        wint_t ungetwc(wint_t c, FILE *stream);
-        double wcstod(const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr);
-        float wcstof(const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr);
-        long double wcstold(const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr);
-        long int wcstol(const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr, int base);
-        long long int wcstoll(const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr, int base);
-        unsigned long int wcstoul(const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr, int base);
-        unsigned long long int wcstoull(
-             const wchar_t * restrict nptr,
-             wchar_t ** restrict endptr, int base);
-        wchar_t *wcscpy(wchar_t * restrict s1,
-             const wchar_t * restrict s2);
-        wchar_t *wcsncpy(wchar_t * restrict s1,
-             const wchar_t * restrict s2, size_t n);
-
-
-
-[page 493] (Contents)
-
-      wchar_t *wmemcpy(wchar_t * restrict s1,
-           const wchar_t * restrict s2, size_t n);
-      wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
-           size_t n);
-      wchar_t *wcscat(wchar_t * restrict s1,
-           const wchar_t * restrict s2);
-      wchar_t *wcsncat(wchar_t * restrict s1,
-           const wchar_t * restrict s2, size_t n);
-      int wcscmp(const wchar_t *s1, const wchar_t *s2);
-      int wcscoll(const wchar_t *s1, const wchar_t *s2);
-      int wcsncmp(const wchar_t *s1, const wchar_t *s2,
-           size_t n);
-      size_t wcsxfrm(wchar_t * restrict s1,
-           const wchar_t * restrict s2, size_t n);
-      int wmemcmp(const wchar_t *s1, const wchar_t *s2,
-           size_t n);
-      wchar_t *wcschr(const wchar_t *s, wchar_t c);
-      size_t wcscspn(const wchar_t *s1, const wchar_t *s2);
-      wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);
-      wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
-      size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
-      wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);
-      wchar_t *wcstok(wchar_t * restrict s1,
-           const wchar_t * restrict s2,
-           wchar_t ** restrict ptr);
-      wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);
-      size_t wcslen(const wchar_t *s);
-      wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
-      size_t wcsftime(wchar_t * restrict s, size_t maxsize,
-           const wchar_t * restrict format,
-           const struct tm * restrict timeptr);
-      wint_t btowc(int c);
-      int wctob(wint_t c);
-      int mbsinit(const mbstate_t *ps);
-      size_t mbrlen(const char * restrict s, size_t n,
-           mbstate_t * restrict ps);
-      size_t mbrtowc(wchar_t * restrict pwc,
-           const char * restrict s, size_t n,
-           mbstate_t * restrict ps);
-
-
-
-[page 494] (Contents)
-
-        size_t wcrtomb(char * restrict s, wchar_t wc,
-             mbstate_t * restrict ps);
-        size_t mbsrtowcs(wchar_t * restrict dst,
-             const char ** restrict src, size_t len,
-             mbstate_t * restrict ps);
-        size_t wcsrtombs(char * restrict dst,
-             const wchar_t ** restrict src, size_t len,
-             mbstate_t * restrict ps);
-        __STDC_WANT_LIB_EXT1__
-        errno_t
-        rsize_t
-        int fwprintf_s(FILE * restrict stream,
-             const wchar_t * restrict format, ...);
-        int fwscanf_s(FILE * restrict stream,
-             const wchar_t * restrict format, ...);
-        int snwprintf_s(wchar_t * restrict s,
-             rsize_t n,
-             const wchar_t * restrict format, ...);
-        int swprintf_s(wchar_t * restrict s, rsize_t n,
-             const wchar_t * restrict format, ...);
-        int swscanf_s(const wchar_t * restrict s,
-             const wchar_t * restrict format, ...);
-        int vfwprintf_s(FILE * restrict stream,
-             const wchar_t * restrict format,
-             va_list arg);
-        int vfwscanf_s(FILE * restrict stream,
-             const wchar_t * restrict format, va_list arg);
-        int vsnwprintf_s(wchar_t * restrict s,
-             rsize_t n,
-             const wchar_t * restrict format,
-             va_list arg);
-        int vswprintf_s(wchar_t * restrict s,
-             rsize_t n,
-             const wchar_t * restrict format,
-             va_list arg);
-        int vswscanf_s(const wchar_t * restrict s,
-             const wchar_t * restrict format,
-             va_list arg);
-
-
-
-[page 495] (Contents)
-
-      int vwprintf_s(const wchar_t * restrict format,
-           va_list arg);
-      int vwscanf_s(const wchar_t * restrict format,
-           va_list arg);
-      int wprintf_s(const wchar_t * restrict format, ...);
-      int wscanf_s(const wchar_t * restrict format, ...);
-      errno_t wcscpy_s(wchar_t * restrict s1,
-           rsize_t s1max,
-           const wchar_t * restrict s2);
-      errno_t wcsncpy_s(wchar_t * restrict s1,
-           rsize_t s1max,
-           const wchar_t * restrict s2,
-           rsize_t n);
-      errno_t wmemcpy_s(wchar_t * restrict s1,
-           rsize_t s1max,
-           const wchar_t * restrict s2,
-           rsize_t n);
-      errno_t wmemmove_s(wchar_t *s1, rsize_t s1max,
-           const wchar_t *s2, rsize_t n);
-      errno_t wcscat_s(wchar_t * restrict s1,
-           rsize_t s1max,
-           const wchar_t * restrict s2);
-      errno_t wcsncat_s(wchar_t * restrict s1,
-           rsize_t s1max,
-           const wchar_t * restrict s2,
-           rsize_t n);
-      wchar_t *wcstok_s(wchar_t * restrict s1,
-           rsize_t * restrict s1max,
-           const wchar_t * restrict s2,
-           wchar_t ** restrict ptr);
-      size_t wcsnlen_s(const wchar_t *s, size_t maxsize);
-      errno_t wcrtomb_s(size_t * restrict retval,
-           char * restrict s, rsize_t smax,
-           wchar_t wc, mbstate_t * restrict ps);
-      errno_t mbsrtowcs_s(size_t * restrict retval,
-           wchar_t * restrict dst, rsize_t dstmax,
-           const char ** restrict src, rsize_t len,
-           mbstate_t * restrict ps);
-
-
-
-
-[page 496] (Contents)
-
-        errno_t wcsrtombs_s(size_t * restrict retval,
-             char * restrict dst, rsize_t dstmax,
-             const wchar_t ** restrict src, rsize_t len,
-             mbstate_t * restrict ps);
-B.28 Wide character classification and mapping utilities <wctype.h>
-        wint_t       wctrans_t         wctype_t         WEOF
-        int iswalnum(wint_t wc);
-        int iswalpha(wint_t wc);
-        int iswblank(wint_t wc);
-        int iswcntrl(wint_t wc);
-        int iswdigit(wint_t wc);
-        int iswgraph(wint_t wc);
-        int iswlower(wint_t wc);
-        int iswprint(wint_t wc);
-        int iswpunct(wint_t wc);
-        int iswspace(wint_t wc);
-        int iswupper(wint_t wc);
-        int iswxdigit(wint_t wc);
-        int iswctype(wint_t wc, wctype_t desc);
-        wctype_t wctype(const char *property);
-        wint_t towlower(wint_t wc);
-        wint_t towupper(wint_t wc);
-        wint_t towctrans(wint_t wc, wctrans_t desc);
-        wctrans_t wctrans(const char *property);
-
-
-
-
-[page 497] (Contents)
-
-                                          Annex C
-                                        (informative)
-                                      Sequence points
-1   The following are the sequence points described in 5.1.2.3:
-    -- Between the evaluations of the function designator and actual arguments in a function
-      call and the actual call. (6.5.2.2).
-    -- Between the evaluations of the first and second operands of the following operators:
-      logical AND && (6.5.13); logical OR || (6.5.14); comma , (6.5.17).
-    -- Between the evaluations of the first operand of the conditional ? : operator and
-      whichever of the second and third operands is evaluated (6.5.15).
-    -- The end of a full declarator: declarators (6.7.6);
-    -- Between the evaluation of a full expression and the next full expression to be
-      evaluated. The following are full expressions: an initializer that is not part of a
-      compound literal (6.7.9); the expression in an expression statement (6.8.3); the
-      controlling expression of a selection statement (if or switch) (6.8.4); the
-      controlling expression of a while or do statement (6.8.5); each of the (optional)
-      expressions of a for statement (6.8.5.3); the (optional) expression in a return
-      statement (6.8.6.4).
-    -- Immediately before a library function returns (7.1.4).
-    -- After the actions associated with each formatted input/output function conversion
-      specifier (7.21.6, 7.28.2).
-    -- Immediately before and immediately after each call to a comparison function, and
-      also between any call to a comparison function and any movement of the objects
-      passed as arguments to that call (7.22.5).
-
-
-
-
-[page 498] (Contents)
-
-                                         Annex D
-                                        (normative)
-                   Universal character names for identifiers
-1   This clause lists the hexadecimal code values that are valid in universal character names
-    in identifiers.
-2   This table is reproduced unchanged from ISO/IEC TR 10176:1998, produced by ISO/IEC
-    JTC 1/SC 22/WG 20, except for the omission of ranges that are part of the basic character
-    sets.
-    Latin:            00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217,
-                      0250-02A8, 1E00-1E9B, 1EA0-1EF9, 207F
-    Greek:            0386, 0388-038A, 038C, 038E-03A1, 03A3-03CE, 03D0-03D6,
-                      03DA, 03DC, 03DE, 03E0, 03E2-03F3, 1F00-1F15, 1F18-1F1D,
-                      1F20-1F45, 1F48-1F4D, 1F50-1F57, 1F59, 1F5B, 1F5D,
-                      1F5F-1F7D, 1F80-1FB4, 1FB6-1FBC, 1FC2-1FC4, 1FC6-1FCC,
-                      1FD0-1FD3, 1FD6-1FDB, 1FE0-1FEC, 1FF2-1FF4, 1FF6-1FFC
-    Cyrillic:         0401-040C, 040E-044F, 0451-045C, 045E-0481, 0490-04C4,
-                      04C7-04C8, 04CB-04CC, 04D0-04EB, 04EE-04F5, 04F8-04F9
-    Armenian:         0531-0556, 0561-0587
-    Hebrew:           05B0-05B9,      05BB-05BD,       05BF,   05C1-05C2,      05D0-05EA,
-                      05F0-05F2
-    Arabic:           0621-063A, 0640-0652, 0670-06B7, 06BA-06BE, 06C0-06CE,
-                      06D0-06DC, 06E5-06E8, 06EA-06ED
-    Devanagari:       0901-0903, 0905-0939, 093E-094D, 0950-0952, 0958-0963
-    Bengali:          0981-0983, 0985-098C, 098F-0990, 0993-09A8, 09AA-09B0,
-                      09B2, 09B6-09B9, 09BE-09C4, 09C7-09C8, 09CB-09CD,
-                      09DC-09DD, 09DF-09E3, 09F0-09F1
-    Gurmukhi:         0A02, 0A05-0A0A, 0A0F-0A10, 0A13-0A28, 0A2A-0A30,
-                      0A32-0A33, 0A35-0A36, 0A38-0A39, 0A3E-0A42, 0A47-0A48,
-                      0A4B-0A4D, 0A59-0A5C, 0A5E, 0A74
-    Gujarati:         0A81-0A83, 0A85-0A8B, 0A8D, 0A8F-0A91, 0A93-0AA8,
-                      0AAA-0AB0,    0AB2-0AB3,     0AB5-0AB9, 0ABD-0AC5,
-                      0AC7-0AC9, 0ACB-0ACD, 0AD0, 0AE0
-    Oriya:            0B01-0B03, 0B05-0B0C, 0B0F-0B10, 0B13-0B28, 0B2A-0B30,
-                      0B32-0B33, 0B36-0B39, 0B3E-0B43, 0B47-0B48, 0B4B-0B4D,
-[page 499] (Contents)
-
-                0B5C-0B5D, 0B5F-0B61
-Tamil:          0B82-0B83, 0B85-0B8A, 0B8E-0B90, 0B92-0B95, 0B99-0B9A,
-                0B9C, 0B9E-0B9F, 0BA3-0BA4, 0BA8-0BAA, 0BAE-0BB5,
-                0BB7-0BB9, 0BBE-0BC2, 0BC6-0BC8, 0BCA-0BCD
-Telugu:         0C01-0C03, 0C05-0C0C, 0C0E-0C10, 0C12-0C28, 0C2A-0C33,
-                0C35-0C39, 0C3E-0C44, 0C46-0C48, 0C4A-0C4D, 0C60-0C61
-Kannada:        0C82-0C83, 0C85-0C8C, 0C8E-0C90, 0C92-0CA8, 0CAA-0CB3,
-                0CB5-0CB9, 0CBE-0CC4, 0CC6-0CC8, 0CCA-0CCD, 0CDE,
-                0CE0-0CE1
-Malayalam:      0D02-0D03, 0D05-0D0C, 0D0E-0D10, 0D12-0D28, 0D2A-0D39,
-                0D3E-0D43, 0D46-0D48, 0D4A-0D4D, 0D60-0D61
-Thai:           0E01-0E3A, 0E40-0E5B
-Lao:            0E81-0E82, 0E84, 0E87-0E88, 0E8A, 0E8D, 0E94-0E97,
-                0E99-0E9F,   0EA1-0EA3,  0EA5,  0EA7,  0EAA-0EAB,
-                0EAD-0EAE, 0EB0-0EB9, 0EBB-0EBD, 0EC0-0EC4, 0EC6,
-                0EC8-0ECD, 0EDC-0EDD
-Tibetan:        0F00, 0F18-0F19, 0F35, 0F37, 0F39, 0F3E-0F47, 0F49-0F69,
-                0F71-0F84, 0F86-0F8B, 0F90-0F95, 0F97, 0F99-0FAD,
-                0FB1-0FB7, 0FB9
-Georgian:       10A0-10C5, 10D0-10F6
-Hiragana:       3041-3093, 309B-309C
-Katakana:       30A1-30F6, 30FB-30FC
-Bopomofo:       3105-312C
-CJK Unified Ideographs: 4E00-9FA5
-Hangul:         AC00-D7A3
-Digits:         0660-0669, 06F0-06F9, 0966-096F, 09E6-09EF, 0A66-0A6F,
-                0AE6-0AEF, 0B66-0B6F, 0BE7-0BEF, 0C66-0C6F, 0CE6-0CEF,
-                0D66-0D6F, 0E50-0E59, 0ED0-0ED9, 0F20-0F33
-Special characters: 00B5, 00B7, 02B0-02B8, 02BB, 02BD-02C1, 02D0-02D1,
-                   02E0-02E4, 037A, 0559, 093D, 0B3D, 1FBE, 203F-2040, 2102,
-                   2107, 210A-2113, 2115, 2118-211D, 2124, 2126, 2128, 212A-2131,
-                   2133-2138, 2160-2182, 3005-3007, 3021-3029
-
-
-
-
-[page 500] (Contents)
-
-                                         Annex E
-                                       (informative)
-                                Implementation limits
-1   The contents of the header <limits.h> are given below, in alphabetical order. The
-    minimum magnitudes shown shall be replaced by implementation-defined magnitudes
-    with the same sign. The values shall all be constant expressions suitable for use in #if
-    preprocessing directives. The components are described further in 5.2.4.2.1.
-            #define    CHAR_BIT                               8
-            #define    CHAR_MAX          UCHAR_MAX or SCHAR_MAX
-            #define    CHAR_MIN                  0 or SCHAR_MIN
-            #define    INT_MAX                           +32767
-            #define    INT_MIN                           -32767
-            #define    LONG_MAX                     +2147483647
-            #define    LONG_MIN                     -2147483647
-            #define    LLONG_MAX           +9223372036854775807
-            #define    LLONG_MIN           -9223372036854775807
-            #define    MB_LEN_MAX                             1
-            #define    SCHAR_MAX                           +127
-            #define    SCHAR_MIN                           -127
-            #define    SHRT_MAX                          +32767
-            #define    SHRT_MIN                          -32767
-            #define    UCHAR_MAX                            255
-            #define    USHRT_MAX                          65535
-            #define    UINT_MAX                           65535
-            #define    ULONG_MAX                     4294967295
-            #define    ULLONG_MAX          18446744073709551615
-2   The contents of the header <float.h> are given below. All integer values, except
-    FLT_ROUNDS, shall be constant expressions suitable for use in #if preprocessing
-    directives; all floating values shall be constant expressions. The components are
-    described further in 5.2.4.2.2.
-3   The values given in the following list shall be replaced by implementation-defined
-    expressions:
-            #define FLT_EVAL_METHOD
-            #define FLT_ROUNDS
-4   The values given in the following list shall be replaced by implementation-defined
-    constant expressions that are greater or equal in magnitude (absolute value) to those
-    shown, with the same sign:
-[page 501] (Contents)
-
-           #define    DLB_DECIMAL_DIG                                10
-           #define    DBL_DIG                                        10
-           #define    DBL_MANT_DIG
-           #define    DBL_MAX_10_EXP                               +37
-           #define    DBL_MAX_EXP
-           #define    DBL_MIN_10_EXP                               -37
-           #define    DBL_MIN_EXP
-           #define    DECIMAL_DIG                                    10
-           #define    FLT_DECIMAL_DIG                                 6
-           #define    FLT_DIG                                         6
-           #define    FLT_MANT_DIG
-           #define    FLT_MAX_10_EXP                               +37
-           #define    FLT_MAX_EXP
-           #define    FLT_MIN_10_EXP                               -37
-           #define    FLT_MIN_EXP
-           #define    FLT_RADIX                                       2
-           #define    LDLB_DECIMAL_DIG                               10
-           #define    LDBL_DIG                                       10
-           #define    LDBL_MANT_DIG
-           #define    LDBL_MAX_10_EXP                              +37
-           #define    LDBL_MAX_EXP
-           #define    LDBL_MIN_10_EXP                              -37
-           #define    LDBL_MIN_EXP
-5   The values given in the following list shall be replaced by implementation-defined
-    constant expressions with values that are greater than or equal to those shown:
-           #define DBL_MAX                                      1E+37
-           #define FLT_MAX                                      1E+37
-           #define LDBL_MAX                                     1E+37
-6   The values given in the following list shall be replaced by implementation-defined
-    constant expressions with (positive) values that are less than or equal to those shown:
-           #define    DBL_EPSILON                                1E-9
-           #define    DBL_MIN                                   1E-37
-           #define    FLT_EPSILON                                1E-5
-           #define    FLT_MIN                                   1E-37
-           #define    LDBL_EPSILON                               1E-9
-           #define    LDBL_MIN                                  1E-37
-
-
-
-
-[page 502] (Contents)
-
-                                               Annex F
-                                              (normative)
-                          IEC 60559 floating-point arithmetic
-    F.1 Introduction
-1   This annex specifies C language support for the IEC 60559 floating-point standard. The
-    IEC 60559 floating-point standard is specifically Binary floating-point arithmetic for
-    microprocessor systems, second edition (IEC 60559:1989), previously designated
-    IEC 559:1989 and as IEEE Standard for Binary Floating-Point Arithmetic
-    (ANSI/IEEE 754-1985). IEEE Standard for Radix-Independent Floating-Point
-    Arithmetic (ANSI/IEEE 854-1987) generalizes the binary standard to remove
-    dependencies on radix and word length. IEC 60559 generally refers to the floating-point
-    standard, as in IEC 60559 operation, IEC 60559 format, etc. An implementation that
-    defines __STDC_IEC_559__ shall conform to the specifications in this annex.339)
-    Where a binding between the C language and IEC 60559 is indicated, the
-    IEC 60559-specified behavior is adopted by reference, unless stated otherwise. Since
-    negative and positive infinity are representable in IEC 60559 formats, all real numbers lie
-    within the range of representable values.
-    F.2 Types
-1   The C floating types match the IEC 60559 formats as follows:
-    -- The float type matches the IEC 60559 single format.
-    -- The double type matches the IEC 60559 double format.
-    -- The long double type matches an IEC 60559 extended format,340) else a
-      non-IEC 60559 extended format, else the IEC 60559 double format.
-    Any non-IEC 60559 extended format used for the long double type shall have more
-    precision than IEC 60559 double and at least the range of IEC 60559 double.341)
-
-
-
-
-    339) Implementations that do not define __STDC_IEC_559__ are not required to conform to these
-         specifications.
-    340) ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit
-         and quadruple 128-bit IEC 60559 formats.
-    341) A non-IEC 60559 long double type is required to provide infinity and NaNs, as its values include
-         all double values.
-
-[page 503] (Contents)
-
-    Recommended practice
-2   The long double type should match an IEC 60559 extended format.
-    F.2.1 Infinities, signed zeros, and NaNs
-1   This specification does not define the behavior of signaling NaNs.342) It generally uses
-    the term NaN to denote quiet NaNs. The NAN and INFINITY macros and the nan
-    functions in <math.h> provide designations for IEC 60559 NaNs and infinities.
-    F.3 Operators and functions
-1   C operators and functions provide IEC 60559 required and recommended facilities as
-    listed below.
-    -- The +, -, *, and / operators provide the IEC 60559 add, subtract, multiply, and
-      divide operations.
-    -- The sqrt functions in <math.h> provide the IEC 60559 square root operation.
-    -- The remainder functions in <math.h> provide the IEC 60559 remainder
-      operation. The remquo functions in <math.h> provide the same operation but
-      with additional information.
-    -- The rint functions in <math.h> provide the IEC 60559 operation that rounds a
-      floating-point number to an integer value (in the same precision). The nearbyint
-      functions in <math.h> provide the nearbyinteger function recommended in the
-      Appendix to ANSI/IEEE 854.
-    -- The conversions for floating types provide the IEC 60559 conversions between
-      floating-point precisions.
-    -- The conversions from integer to floating types provide the IEC 60559 conversions
-      from integer to floating point.
-    -- The conversions from floating to integer types provide IEC 60559-like conversions
-      but always round toward zero.
-    -- The lrint and llrint functions in <math.h> provide the IEC 60559
-      conversions, which honor the directed rounding mode, from floating point to the
-      long int and long long int integer formats. The lrint and llrint
-      functions can be used to implement IEC 60559 conversions from floating to other
-      integer formats.
-    -- The translation time conversion of floating constants and the strtod, strtof,
-      strtold, fprintf, fscanf, and related library functions in <stdlib.h>,
-
-
-    342) Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are
-         sufficient for closure of the arithmetic.
-
-[page 504] (Contents)
-
-   <stdio.h>, and <wchar.h> provide IEC 60559 binary-decimal conversions. The
-   strtold function in <stdlib.h> provides the conv function recommended in the
-   Appendix to ANSI/IEEE 854.
--- The relational and equality operators provide IEC 60559 comparisons. IEC 60559
-  identifies a need for additional comparison predicates to facilitate writing code that
-  accounts for NaNs. The comparison macros (isgreater, isgreaterequal,
-  isless, islessequal, islessgreater, and isunordered) in <math.h>
-  supplement the language operators to address this need. The islessgreater and
-  isunordered macros provide respectively a quiet version of the <> predicate and
-  the unordered predicate recommended in the Appendix to IEC 60559.
--- The feclearexcept, feraiseexcept, and fetestexcept functions in
-  <fenv.h> provide the facility to test and alter the IEC 60559 floating-point
-  exception status flags. The fegetexceptflag and fesetexceptflag
-  functions in <fenv.h> provide the facility to save and restore all five status flags at
-  one time. These functions are used in conjunction with the type fexcept_t and the
-  floating-point     exception      macros      (FE_INEXACT,         FE_DIVBYZERO,
-  FE_UNDERFLOW, FE_OVERFLOW, FE_INVALID) also in <fenv.h>.
--- The fegetround and fesetround functions in <fenv.h> provide the facility
-  to select among the IEC 60559 directed rounding modes represented by the rounding
-  direction macros in <fenv.h> (FE_TONEAREST, FE_UPWARD, FE_DOWNWARD,
-  FE_TOWARDZERO) and the values 0, 1, 2, and 3 of FLT_ROUNDS are the
-  IEC 60559 directed rounding modes.
--- The fegetenv, feholdexcept, fesetenv, and feupdateenv functions in
-  <fenv.h> provide a facility to manage the floating-point environment, comprising
-  the IEC 60559 status flags and control modes.
--- The copysign functions in <math.h> provide the copysign function
-  recommended in the Appendix to IEC 60559.
--- The fabs functions in <math.h> provide the abs function recommended in the
-  Appendix to IEC 60559.
--- The unary minus (-) operator provides the unary minus (-) operation recommended
-  in the Appendix to IEC 60559.
--- The scalbn and scalbln functions in <math.h> provide the scalb function
-  recommended in the Appendix to IEC 60559.
--- The logb functions in <math.h> provide the logb function recommended in the
-  Appendix to IEC 60559, but following the newer specifications in ANSI/IEEE 854.
--- The nextafter and nexttoward functions in <math.h> provide the nextafter
-  function recommended in the Appendix to IEC 60559 (but with a minor change to
-
-[page 505] (Contents)
-
-        better handle signed zeros).
-    -- The isfinite macro in <math.h> provides the finite function recommended in
-      the Appendix to IEC 60559.
-    -- The isnan macro in <math.h> provides the isnan function recommended in the
-      Appendix to IEC 60559.
-    -- The signbit macro and the fpclassify macro in <math.h>, used in
-      conjunction with the number classification macros (FP_NAN, FP_INFINITE,
-      FP_NORMAL, FP_SUBNORMAL, FP_ZERO), provide the facility of the class
-      function recommended in the Appendix to IEC 60559 (except that the classification
-      macros defined in 7.12.3 do not distinguish signaling from quiet NaNs).
-    F.4 Floating to integer conversion
-1   If the integer type is _Bool, 6.3.1.2 applies and no floating-point exceptions are raised
-    (even for NaN). Otherwise, if the floating value is infinite or NaN or if the integral part
-    of the floating value exceeds the range of the integer type, then the ''invalid'' floating-
-    point exception is raised and the resulting value is unspecified. Otherwise, the resulting
-    value is determined by 6.3.1.4. Conversion of an integral floating value that does not
-    exceed the range of the integer type raises no floating-point exceptions; whether
-    conversion of a non-integral floating value raises the ''inexact'' floating-point exception is
-    unspecified.343)
-    F.5 Binary-decimal conversion
-1   Conversion from the widest supported IEC 60559 format to decimal with
-    DECIMAL_DIG digits and back is the identity function.344)
-2   Conversions involving IEC 60559 formats follow all pertinent recommended practice. In
-    particular, conversion between any supported IEC 60559 format and decimal with
-    DECIMAL_DIG or fewer significant digits is correctly rounded (honoring the current
-    rounding mode), which assures that conversion from the widest supported IEC 60559
-    format to decimal with DECIMAL_DIG digits and back is the identity function.
-
-
-
-    343) ANSI/IEEE 854, but not IEC 60559 (ANSI/IEEE 754), directly specifies that floating-to-integer
-         conversions raise the ''inexact'' floating-point exception for non-integer in-range values. In those
-         cases where it matters, library functions can be used to effect such conversions with or without raising
-         the ''inexact'' floating-point exception. See rint, lrint, llrint, and nearbyint in
-         <math.h>.
-    344) If the minimum-width IEC 60559 extended format (64 bits of precision) is supported,
-         DECIMAL_DIG shall be at least 21. If IEC 60559 double (53 bits of precision) is the widest
-         IEC 60559 format supported, then DECIMAL_DIG shall be at least 17. (By contrast, LDBL_DIG and
-         DBL_DIG are 18 and 15, respectively, for these formats.)
-
-[page 506] (Contents)
-
-3   Functions such as strtod that convert character sequences to floating types honor the
-    rounding direction. Hence, if the rounding direction might be upward or downward, the
-    implementation cannot convert a minus-signed sequence by negating the converted
-    unsigned sequence.
-    F.6 The return statement
-    If the return expression is evaluated in a floating-point format different from the return
-    type, the expression is converted to the return type of the function and the resulting value
-    is returned to the caller.
-    F.7 Contracted expressions
-1   A contracted expression is correctly rounded (once) and treats infinities, NaNs, signed
-    zeros, subnormals, and the rounding directions in a manner consistent with the basic
-    arithmetic operations covered by IEC 60559.
-    Recommended practice
-2   A contracted expression should raise floating-point exceptions in a manner generally
-    consistent with the basic arithmetic operations.
-    F.8 Floating-point environment
-1   The floating-point environment defined in <fenv.h> includes the IEC 60559 floating-
-    point exception status flags and directed-rounding control modes. It includes also
-    IEC 60559 dynamic rounding precision and trap enablement modes, if the
-    implementation supports them.345)
-    F.8.1 Environment management
-1   IEC 60559 requires that floating-point operations implicitly raise floating-point exception
-    status flags, and that rounding control modes can be set explicitly to affect result values of
-    floating-point operations. When the state for the FENV_ACCESS pragma (defined in
-    <fenv.h>) is ''on'', these changes to the floating-point state are treated as side effects
-    which respect sequence points.346)
-
-
-
-
-    345) This specification does not require dynamic rounding precision nor trap enablement modes.
-    346) If the state for the FENV_ACCESS pragma is ''off'', the implementation is free to assume the floating-
-         point control modes will be the default ones and the floating-point status flags will not be tested,
-         which allows certain optimizations (see F.9).
-
-[page 507] (Contents)
-
-    F.8.2 Translation
-1   During translation the IEC 60559 default modes are in effect:
-    -- The rounding direction mode is rounding to nearest.
-    -- The rounding precision mode (if supported) is set so that results are not shortened.
-    -- Trapping or stopping (if supported) is disabled on all floating-point exceptions.
-    Recommended practice
-2   The implementation should produce a diagnostic message for each translation-time
-    floating-point exception, other than ''inexact'';347) the implementation should then
-    proceed with the translation of the program.
-    F.8.3 Execution
-1   At program startup the floating-point environment is initialized as prescribed by
-    IEC 60559:
-    -- All floating-point exception status flags are cleared.
-    -- The rounding direction mode is rounding to nearest.
-    -- The dynamic rounding precision mode (if supported) is set so that results are not
-      shortened.
-    -- Trapping or stopping (if supported) is disabled on all floating-point exceptions.
-    F.8.4 Constant expressions
-1   An arithmetic constant expression of floating type, other than one in an initializer for an
-    object that has static or thread storage duration, is evaluated (as if) during execution; thus,
-    it is affected by any operative floating-point control modes and raises floating-point
-    exceptions as required by IEC 60559 (provided the state for the FENV_ACCESS pragma
-    is ''on'').348)
-2   EXAMPLE
-
-
-
-    347) As floating constants are converted to appropriate internal representations at translation time, their
-         conversion is subject to default rounding modes and raises no execution-time floating-point exceptions
-         (even where the state of the FENV_ACCESS pragma is ''on''). Library functions, for example
-         strtod, provide execution-time conversion of numeric strings.
-    348) Where the state for the FENV_ACCESS pragma is ''on'', results of inexact expressions like 1.0/3.0
-         are affected by rounding modes set at execution time, and expressions such as 0.0/0.0 and
-         1.0/0.0 generate execution-time floating-point exceptions. The programmer can achieve the
-         efficiency of translation-time evaluation through static initialization, such as
-                  const static double one_third = 1.0/3.0;
-
-
-[page 508] (Contents)
-
-             #include <fenv.h>
-             #pragma STDC FENV_ACCESS ON
-             void f(void)
-             {
-                   float w[] = { 0.0/0.0 };                  //   raises an exception
-                   static float x = 0.0/0.0;                 //   does not raise an exception
-                   float y = 0.0/0.0;                        //   raises an exception
-                   double z = 0.0/0.0;                       //   raises an exception
-                   /* ... */
-             }
-3   For the static initialization, the division is done at translation time, raising no (execution-time) floating-
-    point exceptions. On the other hand, for the three automatic initializations the invalid division occurs at
-    execution time.
-
-    F.8.5 Initialization
-1   All computation for automatic initialization is done (as if) at execution time; thus, it is
-    affected by any operative modes and raises floating-point exceptions as required by
-    IEC 60559 (provided the state for the FENV_ACCESS pragma is ''on''). All computation
-    for initialization of objects that have static or thread storage duration is done (as if) at
-    translation time.
-2   EXAMPLE
-             #include <fenv.h>
-             #pragma STDC FENV_ACCESS ON
-             void f(void)
-             {
-                   float u[] = { 1.1e75 };                  //   raises exceptions
-                   static float v = 1.1e75;                 //   does not raise exceptions
-                   float w = 1.1e75;                        //   raises exceptions
-                   double x = 1.1e75;                       //   may raise exceptions
-                   float y = 1.1e75f;                       //   may raise exceptions
-                   long double z = 1.1e75;                  //   does not raise exceptions
-                   /* ... */
-             }
-3   The static initialization of v raises no (execution-time) floating-point exceptions because its computation is
-    done at translation time. The automatic initialization of u and w require an execution-time conversion to
-    float of the wider value 1.1e75, which raises floating-point exceptions. The automatic initializations
-    of x and y entail execution-time conversion; however, in some expression evaluation methods, the
-    conversions is not to a narrower format, in which case no floating-point exception is raised.349) The
-    automatic initialization of z entails execution-time conversion, but not to a narrower format, so no floating-
-    point exception is raised. Note that the conversions of the floating constants 1.1e75 and 1.1e75f to
-
-
-
-    349) Use of float_t and double_t variables increases the likelihood of translation-time computation.
-         For example, the automatic initialization
-                  double_t x = 1.1e75;
-         could be done at translation time, regardless of the expression evaluation method.
-
-[page 509] (Contents)
-
-    their internal representations occur at translation time in all cases.
-
-    F.8.6 Changing the environment
-1   Operations defined in 6.5 and functions and macros defined for the standard libraries
-    change floating-point status flags and control modes just as indicated by their
-    specifications (including conformance to IEC 60559). They do not change flags or modes
-    (so as to be detectable by the user) in any other cases.
-2   If the argument to the feraiseexcept function in <fenv.h> represents IEC 60559
-    valid coincident floating-point exceptions for atomic operations (namely ''overflow'' and
-    ''inexact'', or ''underflow'' and ''inexact''), then ''overflow'' or ''underflow'' is raised
-    before ''inexact''.
-    F.9 Optimization
-1   This section identifies code transformations that might subvert IEC 60559-specified
-    behavior, and others that do not.
-    F.9.1 Global transformations
-1   Floating-point arithmetic operations and external function calls may entail side effects
-    which optimization shall honor, at least where the state of the FENV_ACCESS pragma is
-    ''on''. The flags and modes in the floating-point environment may be regarded as global
-    variables; floating-point operations (+, *, etc.) implicitly read the modes and write the
-    flags.
-2   Concern about side effects may inhibit code motion and removal of seemingly useless
-    code. For example, in
-             #include <fenv.h>
-             #pragma STDC FENV_ACCESS ON
-             void f(double x)
-             {
-                  /* ... */
-                  for (i = 0; i < n; i++) x + 1;
-                  /* ... */
-             }
-    x + 1 might raise floating-point exceptions, so cannot be removed. And since the loop
-    body might not execute (maybe 0 >= n), x + 1 cannot be moved out of the loop. (Of
-    course these optimizations are valid if the implementation can rule out the nettlesome
-    cases.)
-3   This specification does not require support for trap handlers that maintain information
-    about the order or count of floating-point exceptions. Therefore, between function calls,
-    floating-point exceptions need not be precise: the actual order and number of occurrences
-    of floating-point exceptions (> 1) may vary from what the source code expresses. Thus,
-[page 510] (Contents)
-
-    the preceding loop could be treated as
-             if (0 < n) x + 1;
-    F.9.2 Expression transformations
-1   x/2 (<->) x x 0.5          Although similar transformations involving inexact constants
-                           generally do not yield numerically equivalent expressions, if the
-                           constants are exact then such transformations can be made on
-                           IEC 60559 machines and others that round perfectly.
-    1 x x and x/1 (->) x The expressions 1 x x, x/1, and x are equivalent (on IEC 60559
-                      machines, among others).350)
-    x/x (->) 1.0             The expressions x/x and 1.0 are not equivalent if x can be zero,
-                           infinite, or NaN.
-    x - y (<->) x + (-y)       The expressions x - y, x + (-y), and (-y) + x are equivalent (on
-                           IEC 60559 machines, among others).
-    x - y (<->) -(y - x)       The expressions x - y and -(y - x) are not equivalent because 1 - 1
-                           is +0 but -(1 - 1) is -0 (in the default rounding direction).351)
-    x - x (->) 0.0           The expressions x - x and 0.0 are not equivalent if x is a NaN or
-                           infinite.
-    0 x x (->) 0.0           The expressions 0 x x and 0.0 are not equivalent if x is a NaN,
-                           infinite, or -0.
-    x+0(->) x                 The expressions x + 0 and x are not equivalent if x is -0, because
-                           (-0) + (+0) yields +0 (in the default rounding direction), not -0.
-    x-0(->) x                 (+0) - (+0) yields -0 when rounding is downward (toward -(inf)), but
-                           +0 otherwise, and (-0) - (+0) always yields -0; so, if the state of the
-                           FENV_ACCESS pragma is ''off'', promising default rounding, then
-                           the implementation can replace x - 0 by x, even if x might be zero.
-    -x (<->) 0 - x             The expressions -x and 0 - x are not equivalent if x is +0, because
-                           -(+0) yields -0, but 0 - (+0) yields +0 (unless rounding is
-                           downward).
-
-    350) Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
-         other transformations that remove arithmetic operators.
-    351) IEC 60559 prescribes a signed zero to preserve mathematical identities across certain discontinuities.
-         Examples include:
-            1/(1/ (+-) (inf)) is (+-) (inf)
-         and
-            conj(csqrt(z)) is csqrt(conj(z)),
-         for complex z.
-
-[page 511] (Contents)
-
-    F.9.3 Relational operators
-1   x != x (->) false           The expression x != x is true if x is a NaN.
-    x = x (->) true            The expression x = x is false if x is a NaN.
-    x < y (->) isless(x,y) (and similarly for <=, >, >=) Though numerically equal, these
-                   expressions are not equivalent because of side effects when x or y is a
-                   NaN and the state of the FENV_ACCESS pragma is ''on''. This
-                   transformation, which would be desirable if extra code were required
-                   to cause the ''invalid'' floating-point exception for unordered cases,
-                   could be performed provided the state of the FENV_ACCESS pragma
-                   is ''off''.
-    The sense of relational operators shall be maintained. This includes handling unordered
-    cases as expressed by the source code.
-2   EXAMPLE
-             // calls g and raises ''invalid'' if a and b are unordered
-             if (a < b)
-                     f();
-             else
-                     g();
-    is not equivalent to
-             // calls f and raises ''invalid'' if a and b are unordered
-             if (a >= b)
-                     g();
-             else
-                     f();
-    nor to
-             // calls f without raising ''invalid'' if a and b are unordered
-             if (isgreaterequal(a,b))
-                     g();
-             else
-                     f();
-    nor, unless the state of the FENV_ACCESS pragma is ''off'', to
-             // calls g without raising ''invalid'' if a and b are unordered
-             if (isless(a,b))
-                     f();
-             else
-                     g();
-    but is equivalent to
-
-
-
-
-[page 512] (Contents)
-
-            if (!(a < b))
-                  g();
-            else
-                  f();
-
-    F.9.4 Constant arithmetic
-1   The implementation shall honor floating-point exceptions raised by execution-time
-    constant arithmetic wherever the state of the FENV_ACCESS pragma is ''on''. (See F.8.4
-    and F.8.5.) An operation on constants that raises no floating-point exception can be
-    folded during translation, except, if the state of the FENV_ACCESS pragma is ''on'', a
-    further check is required to assure that changing the rounding direction to downward does
-    not alter the sign of the result,352) and implementations that support dynamic rounding
-    precision modes shall assure further that the result of the operation raises no floating-
-    point exception when converted to the semantic type of the operation.
-    F.10 Mathematics <math.h>
-1   This subclause contains specifications of <math.h> facilities that are particularly suited
-    for IEC 60559 implementations.
-2   The Standard C macro HUGE_VAL and its float and long double analogs,
-    HUGE_VALF and HUGE_VALL, expand to expressions whose values are positive
-    infinities.
-3   Special cases for functions in <math.h> are covered directly or indirectly by
-    IEC 60559. The functions that IEC 60559 specifies directly are identified in F.3. The
-    other functions in <math.h> treat infinities, NaNs, signed zeros, subnormals, and
-    (provided the state of the FENV_ACCESS pragma is ''on'') the floating-point status flags
-    in a manner consistent with the basic arithmetic operations covered by IEC 60559.
-4   The expression math_errhandling & MATH_ERREXCEPT shall evaluate to a
-    nonzero value.
-5   The ''invalid'' and ''divide-by-zero'' floating-point exceptions are raised as specified in
-    subsequent subclauses of this annex.
-6   The ''overflow'' floating-point exception is raised whenever an infinity -- or, because of
-    rounding direction, a maximal-magnitude finite number -- is returned in lieu of a value
-    whose magnitude is too large.
-7   The ''underflow'' floating-point exception is raised whenever a result is tiny (essentially
-    subnormal or zero) and suffers loss of accuracy.353)
-
-
-    352) 0 - 0 yields -0 instead of +0 just when the rounding direction is downward.
-    353) IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on
-         when the floating-point exception is raised.
-
-[page 513] (Contents)
-
-8    Whether or when library functions raise the ''inexact'' floating-point exception is
-     unspecified, unless explicitly specified otherwise.
-9    Whether or when library functions raise an undeserved ''underflow'' floating-point
-     exception is unspecified.354) Otherwise, as implied by F.8.6, the <math.h> functions do
-     not raise spurious floating-point exceptions (detectable by the user), other than the
-     ''inexact'' floating-point exception.
-10   Whether the functions honor the rounding direction mode is implementation-defined,
-     unless explicitly specified otherwise.
-11   Functions with a NaN argument return a NaN result and raise no floating-point exception,
-     except where stated otherwise.
-12   The specifications in the following subclauses append to the definitions in <math.h>.
-     For families of functions, the specifications apply to all of the functions even though only
-     the principal function is shown. Unless otherwise specified, where the symbol ''(+-)''
-     occurs in both an argument and the result, the result has the same sign as the argument.
-     Recommended practice
-13   If a function with one or more NaN arguments returns a NaN result, the result should be
-     the same as one of the NaN arguments (after possible type conversion), except perhaps
-     for the sign.
-     F.10.1 Trigonometric functions
-     F.10.1.1 The acos functions
-1    -- acos(1) returns +0.
-     -- acos(x) returns a NaN and raises the ''invalid'' floating-point exception for
-       | x | > 1.
-     F.10.1.2 The asin functions
-1    -- asin((+-)0) returns (+-)0.
-     -- asin(x) returns a NaN and raises the ''invalid'' floating-point exception for
-       | x | > 1.
-
-
-
-
-     354) It is intended that undeserved ''underflow'' and ''inexact'' floating-point exceptions are raised only if
-          avoiding them would be too costly.
-
-[page 514] (Contents)
-
-    F.10.1.3 The atan functions
-1   -- atan((+-)0) returns (+-)0.
-    -- atan((+-)(inf)) returns (+-)pi /2.
-    F.10.1.4 The atan2 functions
-1   -- atan2((+-)0, -0) returns (+-)pi .355)
-    -- atan2((+-)0, +0) returns (+-)0.
-    -- atan2((+-)0, x) returns (+-)pi for x < 0.
-    -- atan2((+-)0, x) returns (+-)0 for x > 0.
-    -- atan2(y, (+-)0) returns -pi /2 for y < 0.
-    -- atan2(y, (+-)0) returns pi /2 for y > 0.
-    -- atan2((+-)y, -(inf)) returns (+-)pi for finite y > 0.
-    -- atan2((+-)y, +(inf)) returns (+-)0 for finite y > 0.
-    -- atan2((+-)(inf), x) returns (+-)pi /2 for finite x.
-    -- atan2((+-)(inf), -(inf)) returns (+-)3pi /4.
-    -- atan2((+-)(inf), +(inf)) returns (+-)pi /4.
-    F.10.1.5 The cos functions
-1   -- cos((+-)0) returns 1.
-    -- cos((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
-    F.10.1.6 The sin functions
-1   -- sin((+-)0) returns (+-)0.
-    -- sin((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
-    F.10.1.7 The tan functions
-1   -- tan((+-)0) returns (+-)0.
-    -- tan((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
-
-
-
-
-    355) atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise
-         the ''divide-by-zero'' floating-point exception.
-
-[page 515] (Contents)
-
-    F.10.2 Hyperbolic functions
-    F.10.2.1 The acosh functions
-1   -- acosh(1) returns +0.
-    -- acosh(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 1.
-    -- acosh(+(inf)) returns +(inf).
-    F.10.2.2 The asinh functions
-1   -- asinh((+-)0) returns (+-)0.
-    -- asinh((+-)(inf)) returns (+-)(inf).
-    F.10.2.3 The atanh functions
-1   -- atanh((+-)0) returns (+-)0.
-    -- atanh((+-)1) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- atanh(x) returns a NaN and raises the ''invalid'' floating-point exception for
-      | x | > 1.
-    F.10.2.4 The cosh functions
-1   -- cosh((+-)0) returns 1.
-    -- cosh((+-)(inf)) returns +(inf).
-    F.10.2.5 The sinh functions
-1   -- sinh((+-)0) returns (+-)0.
-    -- sinh((+-)(inf)) returns (+-)(inf).
-    F.10.2.6 The tanh functions
-1   -- tanh((+-)0) returns (+-)0.
-    -- tanh((+-)(inf)) returns (+-)1.
-    F.10.3 Exponential and logarithmic functions
-    F.10.3.1 The exp functions
-1   -- exp((+-)0) returns 1.
-    -- exp(-(inf)) returns +0.
-    -- exp(+(inf)) returns +(inf).
-
-
-
-
-[page 516] (Contents)
-
-    F.10.3.2 The exp2 functions
-1   -- exp2((+-)0) returns 1.
-    -- exp2(-(inf)) returns +0.
-    -- exp2(+(inf)) returns +(inf).
-    F.10.3.3 The expm1 functions
-1   -- expm1((+-)0) returns (+-)0.
-    -- expm1(-(inf)) returns -1.
-    -- expm1(+(inf)) returns +(inf).
-    F.10.3.4 The frexp functions
-1   -- frexp((+-)0, exp) returns (+-)0, and stores 0 in the object pointed to by exp.
-    -- frexp((+-)(inf), exp) returns (+-)(inf), and stores an unspecified value in the object
-      pointed to by exp.
-    -- frexp(NaN, exp) stores an unspecified value in the object pointed to by exp
-      (and returns a NaN).
-2   frexp raises no floating-point exceptions.
-3   When the radix of the argument is a power of 2, the returned value is exact and is
-    independent of the current rounding direction mode.
-4   On a binary system, the body of the frexp function might be
-            {
-                   *exp = (value == 0) ? 0 : (int)(1 + logb(value));
-                   return scalbn(value, -(*exp));
-            }
-    F.10.3.5 The ilogb functions
-1   When the correct result is representable in the range of the return type, the returned value
-    is exact and is independent of the current rounding direction mode.
-2   If the correct result is outside the range of the return type, the numeric result is
-    unspecified and the ''invalid'' floating-point exception is raised.
-
-
-
-
-[page 517] (Contents)
-
-    F.10.3.6 The ldexp functions
-1   On a binary system, ldexp(x, exp) is equivalent to scalbn(x, exp).
-    F.10.3.7 The log functions
-1   -- log((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- log(1) returns +0.
-    -- log(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 0.
-    -- log(+(inf)) returns +(inf).
-    F.10.3.8 The log10 functions
-1   -- log10((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- log10(1) returns +0.
-    -- log10(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 0.
-    -- log10(+(inf)) returns +(inf).
-    F.10.3.9 The log1p functions
-1   -- log1p((+-)0) returns (+-)0.
-    -- log1p(-1) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- log1p(x) returns a NaN and raises the ''invalid'' floating-point exception for
-      x < -1.
-    -- log1p(+(inf)) returns +(inf).
-    F.10.3.10 The log2 functions
-1   -- log2((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- log2(1) returns +0.
-    -- log2(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 0.
-    -- log2(+(inf)) returns +(inf).
-    F.10.3.11 The logb functions
-1   -- logb((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- logb((+-)(inf)) returns +(inf).
-2   The returned value is exact and is independent of the current rounding direction mode.
-
-
-
-
-[page 518] (Contents)
-
-    F.10.3.12 The modf functions
-1   -- modf((+-)x, iptr) returns a result with the same sign as x.
-    -- modf((+-)(inf), iptr) returns (+-)0 and stores (+-)(inf) in the object pointed to by iptr.
-    -- modf(NaN, iptr) stores a NaN in the object pointed to by iptr (and returns a
-      NaN).
-2   The returned values are exact and are independent of the current rounding direction
-    mode.
-3   modf behaves as though implemented by
-            #include <math.h>
-            #include <fenv.h>
-            #pragma STDC FENV_ACCESS ON
-            double modf(double value, double *iptr)
-            {
-                 int save_round = fegetround();
-                 fesetround(FE_TOWARDZERO);
-                 *iptr = nearbyint(value);
-                 fesetround(save_round);
-                 return copysign(
-                      isinf(value) ? 0.0 :
-                           value - (*iptr), value);
-            }
-    F.10.3.13 The scalbn and scalbln functions
-1   -- scalbn((+-)0, n) returns (+-)0.
-    -- scalbn(x, 0) returns x.
-    -- scalbn((+-)(inf), n) returns (+-)(inf).
-    F.10.4 Power and absolute value functions
-    F.10.4.1 The cbrt functions
-1   -- cbrt((+-)0) returns (+-)0.
-    -- cbrt((+-)(inf)) returns (+-)(inf).
-
-
-
-
-[page 519] (Contents)
-
-    F.10.4.2 The fabs functions
-1   -- fabs((+-)0) returns +0.
-    -- fabs((+-)(inf)) returns +(inf).
-2   The returned value is exact and is independent of the current rounding direction mode.
-    F.10.4.3 The hypot functions
-1   -- hypot(x, y), hypot(y, x), and hypot(x, -y) are equivalent.
-    -- hypot(x, (+-)0) is equivalent to fabs(x).
-    -- hypot((+-)(inf), y) returns +(inf), even if y is a NaN.
-    F.10.4.4 The pow functions
-1   -- pow((+-)0, y) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception
-      for y an odd integer < 0.
-    -- pow((+-)0, y) returns +(inf) and raises the ''divide-by-zero'' floating-point exception
-      for y < 0 and not an odd integer.
-    -- pow((+-)0, y) returns (+-)0 for y an odd integer > 0.
-    -- pow((+-)0, y) returns +0 for y > 0 and not an odd integer.
-    -- pow(-1, (+-)(inf)) returns 1.
-    -- pow(+1, y) returns 1 for any y, even a NaN.
-    -- pow(x, (+-)0) returns 1 for any x, even a NaN.
-    -- pow(x, y) returns a NaN and raises the ''invalid'' floating-point exception for
-      finite x < 0 and finite non-integer y.
-    -- pow(x, -(inf)) returns +(inf) for | x | < 1.
-    -- pow(x, -(inf)) returns +0 for | x | > 1.
-    -- pow(x, +(inf)) returns +0 for | x | < 1.
-    -- pow(x, +(inf)) returns +(inf) for | x | > 1.
-    -- pow(-(inf), y) returns -0 for y an odd integer < 0.
-    -- pow(-(inf), y) returns +0 for y < 0 and not an odd integer.
-    -- pow(-(inf), y) returns -(inf) for y an odd integer > 0.
-    -- pow(-(inf), y) returns +(inf) for y > 0 and not an odd integer.
-    -- pow(+(inf), y) returns +0 for y < 0.
-    -- pow(+(inf), y) returns +(inf) for y > 0.
-
-
-[page 520] (Contents)
-
-    F.10.4.5 The sqrt functions
-1   sqrt is fully specified as a basic arithmetic operation in IEC 60559. The returned value
-    is dependent on the current rounding direction mode.
-    F.10.5 Error and gamma functions
-    F.10.5.1 The erf functions
-1   -- erf((+-)0) returns (+-)0.
-    -- erf((+-)(inf)) returns (+-)1.
-    F.10.5.2 The erfc functions
-1   -- erfc(-(inf)) returns 2.
-    -- erfc(+(inf)) returns +0.
-    F.10.5.3 The lgamma functions
-1   -- lgamma(1) returns +0.
-    -- lgamma(2) returns +0.
-    -- lgamma(x) returns +(inf) and raises the ''divide-by-zero'' floating-point exception for
-      x a negative integer or zero.
-    -- lgamma(-(inf)) returns +(inf).
-    -- lgamma(+(inf)) returns +(inf).
-    F.10.5.4 The tgamma functions
-1   -- tgamma((+-)0) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception.
-    -- tgamma(x) returns a NaN and raises the ''invalid'' floating-point exception for x a
-      negative integer.
-    -- tgamma(-(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
-    -- tgamma(+(inf)) returns +(inf).
-    F.10.6 Nearest integer functions
-    F.10.6.1 The ceil functions
-1   -- ceil((+-)0) returns (+-)0.
-    -- ceil((+-)(inf)) returns (+-)(inf).
-2   The returned value is exact and is independent of the current rounding direction mode.
-3   The double version of ceil behaves as though implemented by
-
-
-
-[page 521] (Contents)
-
-           #include <math.h>
-           #include <fenv.h>
-           #pragma STDC FENV_ACCESS ON
-           double ceil(double x)
-           {
-                double result;
-                int save_round = fegetround();
-                fesetround(FE_UPWARD);
-                result = rint(x); // or nearbyint instead of rint
-                fesetround(save_round);
-                return result;
-           }
-    F.10.6.2 The floor functions
-1   -- floor((+-)0) returns (+-)0.
-    -- floor((+-)(inf)) returns (+-)(inf).
-2   The returned value is exact and is independent of the current rounding direction mode.
-3   See the sample implementation for ceil in F.10.6.1.
-    F.10.6.3 The nearbyint functions
-1   The nearbyint functions use IEC 60559 rounding according to the current rounding
-    direction. They do not raise the ''inexact'' floating-point exception if the result differs in
-    value from the argument.
-    -- nearbyint((+-)0) returns (+-)0 (for all rounding directions).
-    -- nearbyint((+-)(inf)) returns (+-)(inf) (for all rounding directions).
-    F.10.6.4 The rint functions
-1   The rint functions differ from the nearbyint functions only in that they do raise the
-    ''inexact'' floating-point exception if the result differs in value from the argument.
-    F.10.6.5 The lrint and llrint functions
-1   The lrint and llrint functions provide floating-to-integer conversion as prescribed
-    by IEC 60559. They round according to the current rounding direction. If the rounded
-    value is outside the range of the return type, the numeric result is unspecified and the
-    ''invalid'' floating-point exception is raised. When they raise no other floating-point
-    exception and the result differs from the argument, they raise the ''inexact'' floating-point
-    exception.
-
-
-
-
-[page 522] (Contents)
-
-    F.10.6.6 The round functions
-1   -- round((+-)0) returns (+-)0.
-    -- round((+-)(inf)) returns (+-)(inf).
-2   The double version of round behaves as though implemented by
-            #include <math.h>
-            #include <fenv.h>
-            #pragma STDC FENV_ACCESS ON
-            double round(double x)
-            {
-                 double result;
-                 fenv_t save_env;
-                 feholdexcept(&save_env);
-                 result = rint(x);
-                 if (fetestexcept(FE_INEXACT)) {
-                      fesetround(FE_TOWARDZERO);
-                      result = rint(copysign(0.5 + fabs(x), x));
-                 }
-                 feupdateenv(&save_env);
-                 return result;
-            }
-    The round functions may, but are not required to, raise the ''inexact'' floating-point
-    exception for non-integer numeric arguments, as this implementation does.
-    F.10.6.7 The lround and llround functions
-1   The lround and llround functions differ from the lrint and llrint functions
-    with the default rounding direction just in that the lround and llround functions
-    round halfway cases away from zero and need not raise the ''inexact'' floating-point
-    exception for non-integer arguments that round to within the range of the return type.
-    F.10.6.8 The trunc functions
-1   The trunc functions use IEC 60559 rounding toward zero (regardless of the current
-    rounding direction). The returned value is exact.
-    -- trunc((+-)0) returns (+-)0.
-    -- trunc((+-)(inf)) returns (+-)(inf).
-
-
-
-
-[page 523] (Contents)
-
-    F.10.7 Remainder functions
-    F.10.7.1 The fmod functions
-1   -- fmod((+-)0, y) returns (+-)0 for y not zero.
-    -- fmod(x, y) returns a NaN and raises the ''invalid'' floating-point exception for x
-      infinite or y zero.
-    -- fmod(x, (+-)(inf)) returns x for x not infinite.
-2   When subnormal results are supported, the returned value is exact and is independent of
-    the current rounding direction mode.
-3   The double version of fmod behaves as though implemented by
-           #include <math.h>
-           #include <fenv.h>
-           #pragma STDC FENV_ACCESS ON
-           double fmod(double x, double y)
-           {
-                double result;
-                result = remainder(fabs(x), (y = fabs(y)));
-                if (signbit(result)) result += y;
-                return copysign(result, x);
-           }
-    F.10.7.2 The remainder functions
-1   The remainder functions are fully specified as a basic arithmetic operation in
-    IEC 60559.
-2   When subnormal results are supported, the returned value is exact and is independent of
-    the current rounding direction mode.
-    F.10.7.3 The remquo functions
-1   The remquo functions follow the specifications for the remainder functions. They
-    have no further specifications special to IEC 60559 implementations.
-2   When subnormal results are supported, the returned value is exact and is independent of
-    the current rounding direction mode.
-
-
-
-
-[page 524] (Contents)
-
-    F.10.8 Manipulation functions
-    F.10.8.1 The copysign functions
-1   copysign is specified in the Appendix to IEC 60559.
-2   The returned value is exact and is independent of the current rounding direction mode.
-    F.10.8.2 The nan functions
-1   All IEC 60559 implementations support quiet NaNs, in all floating formats.
-2   The returned value is exact and is independent of the current rounding direction mode.
-    F.10.8.3 The nextafter functions
-1   -- nextafter(x, y) raises the ''overflow'' and ''inexact'' floating-point exceptions
-      for x finite and the function value infinite.
-    -- nextafter(x, y) raises the ''underflow'' and ''inexact'' floating-point
-      exceptions for the function value subnormal or zero and x != y.
-2   Even though underflow or overflow can occur, the returned value is independent of the
-    current rounding direction mode.
-    F.10.8.4 The nexttoward functions
-1   No additional requirements beyond those on nextafter.
-2   Even though underflow or overflow can occur, the returned value is independent of the
-    current rounding direction mode.
-    F.10.9 Maximum, minimum, and positive difference functions
-    F.10.9.1 The fdim functions
-1   No additional requirements.
-    F.10.9.2 The fmax functions
-1   If just one argument is a NaN, the fmax functions return the other argument (if both
-    arguments are NaNs, the functions return a NaN).
-2   The returned value is exact and is independent of the current rounding direction mode.
-3   The body of the fmax function might be356)
-            { return (isgreaterequal(x, y) ||
-                 isnan(y)) ? x : y; }
-
-
-
-    356) Ideally, fmax would be sensitive to the sign of zero, for example fmax(-0.0, +0.0) would
-         return +0; however, implementation in software might be impractical.
-
-[page 525] (Contents)
-
-    F.10.9.3 The fmin functions
-1   The fmin functions are analogous to the fmax functions (see F.10.9.2).
-2   The returned value is exact and is independent of the current rounding direction mode.
-    F.10.10 Floating multiply-add
-    F.10.10.1 The fma functions
-1   -- fma(x, y, z) computes xy + z, correctly rounded once.
-    -- fma(x, y, z) returns a NaN and optionally raises the ''invalid'' floating-point
-      exception if one of x and y is infinite, the other is zero, and z is a NaN.
-    -- fma(x, y, z) returns a NaN and raises the ''invalid'' floating-point exception if
-      one of x and y is infinite, the other is zero, and z is not a NaN.
-    -- fma(x, y, z) returns a NaN and raises the ''invalid'' floating-point exception if x
-      times y is an exact infinity and z is also an infinity but with the opposite sign.
-    F.10.11 Comparison macros
-1   Relational operators and their corresponding comparison macros (7.12.14) produce
-    equivalent result values, even if argument values are represented in wider formats. Thus,
-    comparison macro arguments represented in formats wider than their semantic types are
-    not converted to the semantic types, unless the wide evaluation method converts operands
-    of relational operators to their semantic types. The standard wide evaluation methods
-    characterized by FLT_EVAL_METHOD equal to 1 or 2 (5.2.4.2.2), do not convert
-    operands of relational operators to their semantic types.
-
-
-
-
-[page 526] (Contents)
-
-                                          Annex G
-                                        (informative)
-                  IEC 60559-compatible complex arithmetic
-    G.1 Introduction
-1   This annex supplements annex F to specify complex arithmetic for compatibility with
-    IEC 60559 real floating-point arithmetic. Although these specifications have been
-    carefully designed, there is little existing practice to validate the design decisions.
-    Therefore, these specifications are not normative, but should be viewed more as
-    recommended          practice.       An         implementation        that     defines
-    __STDC_IEC_559_COMPLEX__ should conform to the specifications in this annex.
-    G.2 Types
-1   There is a new keyword _Imaginary, which is used to specify imaginary types. It is
-    used as a type specifier within declaration specifiers in the same way as _Complex is
-    (thus, _Imaginary float is a valid type name).
-2   There are three imaginary types, designated as float _Imaginary, double
-    _Imaginary, and long double _Imaginary. The imaginary types (along with
-    the real floating and complex types) are floating types.
-3   For imaginary types, the corresponding real type is given by deleting the keyword
-    _Imaginary from the type name.
-4   Each imaginary type has the same representation and alignment requirements as the
-    corresponding real type. The value of an object of imaginary type is the value of the real
-    representation times the imaginary unit.
-5   The imaginary type domain comprises the imaginary types.
-    G.3 Conventions
-1   A complex or imaginary value with at least one infinite part is regarded as an infinity
-    (even if its other part is a NaN). A complex or imaginary value is a finite number if each
-    of its parts is a finite number (neither infinite nor NaN). A complex or imaginary value is
-    a zero if each of its parts is a zero.
-
-
-
-
-[page 527] (Contents)
-
-    G.4 Conversions
-    G.4.1 Imaginary types
-1   Conversions among imaginary types follow rules analogous to those for real floating
-    types.
-    G.4.2 Real and imaginary
-1   When a value of imaginary type is converted to a real type other than _Bool,357) the
-    result is a positive zero.
-2   When a value of real type is converted to an imaginary type, the result is a positive
-    imaginary zero.
-    G.4.3 Imaginary and complex
-1   When a value of imaginary type is converted to a complex type, the real part of the
-    complex result value is a positive zero and the imaginary part of the complex result value
-    is determined by the conversion rules for the corresponding real types.
-2   When a value of complex type is converted to an imaginary type, the real part of the
-    complex value is discarded and the value of the imaginary part is converted according to
-    the conversion rules for the corresponding real types.
-    G.5 Binary operators
-1   The following subclauses supplement 6.5 in order to specify the type of the result for an
-    operation with an imaginary operand.
-2   For most operand types, the value of the result of a binary operator with an imaginary or
-    complex operand is completely determined, with reference to real arithmetic, by the usual
-    mathematical formula. For some operand types, the usual mathematical formula is
-    problematic because of its treatment of infinities and because of undue overflow or
-    underflow; in these cases the result satisfies certain properties (specified in G.5.1), but is
-    not completely determined.
-
-
-
-
-    357) See 6.3.1.2.
-
-[page 528] (Contents)
-
-    G.5.1 Multiplicative operators
-    Semantics
-1   If one operand has real type and the other operand has imaginary type, then the result has
-    imaginary type. If both operands have imaginary type, then the result has real type. (If
-    either operand has complex type, then the result has complex type.)
-2   If the operands are not both complex, then the result and floating-point exception
-    behavior of the * operator is defined by the usual mathematical formula:
-           *                  u                   iv                 u + iv
-
-           x                  xu                i(xv)            (xu) + i(xv)
-
-           iy               i(yu)                -yv            (-yv) + i(yu)
-
-           x + iy       (xu) + i(yu)        (-yv) + i(xv)
-3   If the second operand is not complex, then the result and floating-point exception
-    behavior of the / operator is defined by the usual mathematical formula:
-           /                   u                       iv
-
-           x                  x/u                 i(-x/v)
-
-           iy               i(y/u)                     y/v
-
-           x + iy       (x/u) + i(y/u)        (y/v) + i(-x/v)
-4   The * and / operators satisfy the following infinity properties for all real, imaginary, and
-    complex operands:358)
-    -- if one operand is an infinity and the other operand is a nonzero finite number or an
-      infinity, then the result of the * operator is an infinity;
-    -- if the first operand is an infinity and the second operand is a finite number, then the
-      result of the / operator is an infinity;
-    -- if the first operand is a finite number and the second operand is an infinity, then the
-      result of the / operator is a zero;
-
-
-
-
-    358) These properties are already implied for those cases covered in the tables, but are required for all cases
-         (at least where the state for CX_LIMITED_RANGE is ''off'').
-
-[page 529] (Contents)
-
-    -- if the first operand is a nonzero finite number or an infinity and the second operand is
-      a zero, then the result of the / operator is an infinity.
-5   If both operands of the * operator are complex or if the second operand of the / operator
-    is complex, the operator raises floating-point exceptions if appropriate for the calculation
-    of the parts of the result, and may raise spurious floating-point exceptions.
-6   EXAMPLE 1 Multiplication of double _Complex operands could be implemented as follows. Note
-    that the imaginary unit I has imaginary type (see G.6).
-           #include <math.h>
-           #include <complex.h>
-           /* Multiply z * w ... */
-           double complex _Cmultd(double complex z, double complex w)
-           {
-                  #pragma STDC FP_CONTRACT OFF
-                  double a, b, c, d, ac, bd, ad, bc, x, y;
-                  a = creal(z); b = cimag(z);
-                  c = creal(w); d = cimag(w);
-                  ac = a * c;       bd = b * d;
-                  ad = a * d;       bc = b * c;
-                  x = ac - bd; y = ad + bc;
-                  if (isnan(x) && isnan(y)) {
-                          /* Recover infinities that computed as NaN+iNaN ... */
-                          int recalc = 0;
-                          if ( isinf(a) || isinf(b) ) { // z is infinite
-                                  /* "Box" the infinity and change NaNs in the other factor to 0 */
-                                  a = copysign(isinf(a) ? 1.0 : 0.0, a);
-                                  b = copysign(isinf(b) ? 1.0 : 0.0, b);
-                                  if (isnan(c)) c = copysign(0.0, c);
-                                  if (isnan(d)) d = copysign(0.0, d);
-                                  recalc = 1;
-                          }
-                          if ( isinf(c) || isinf(d) ) { // w is infinite
-                                  /* "Box" the infinity and change NaNs in the other factor to 0 */
-                                  c = copysign(isinf(c) ? 1.0 : 0.0, c);
-                                  d = copysign(isinf(d) ? 1.0 : 0.0, d);
-                                  if (isnan(a)) a = copysign(0.0, a);
-                                  if (isnan(b)) b = copysign(0.0, b);
-                                  recalc = 1;
-                          }
-                          if (!recalc && (isinf(ac) || isinf(bd) ||
-                                                 isinf(ad) || isinf(bc))) {
-                                  /* Recover infinities from overflow by changing NaNs to 0 ... */
-                                  if (isnan(a)) a = copysign(0.0, a);
-                                  if (isnan(b)) b = copysign(0.0, b);
-                                  if (isnan(c)) c = copysign(0.0, c);
-                                  if (isnan(d)) d = copysign(0.0, d);
-                                  recalc = 1;
-                          }
-                          if (recalc) {
-
-[page 530] (Contents)
-
-                                      x = INFINITY * ( a * c - b * d );
-                                      y = INFINITY * ( a * d + b * c );
-                           }
-                     }
-                     return x + I * y;
-             }
-7   This implementation achieves the required treatment of infinities at the cost of only one isnan test in
-    ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur.
-
-8   EXAMPLE 2      Division of two double _Complex operands could be implemented as follows.
-             #include <math.h>
-             #include <complex.h>
-             /* Divide z / w ... */
-             double complex _Cdivd(double complex z, double complex w)
-             {
-                    #pragma STDC FP_CONTRACT OFF
-                    double a, b, c, d, logbw, denom, x, y;
-                    int ilogbw = 0;
-                    a = creal(z); b = cimag(z);
-                    c = creal(w); d = cimag(w);
-                    logbw = logb(fmax(fabs(c), fabs(d)));
-                    if (isfinite(logbw)) {
-                           ilogbw = (int)logbw;
-                           c = scalbn(c, -ilogbw); d = scalbn(d, -ilogbw);
-                    }
-                    denom = c * c + d * d;
-                    x = scalbn((a * c + b * d) / denom, -ilogbw);
-                    y = scalbn((b * c - a * d) / denom, -ilogbw);
-                     /* Recover infinities and zeros that computed as NaN+iNaN;                 */
-                     /* the only cases are nonzero/zero, infinite/finite, and finite/infinite, ... */
-                     if (isnan(x) && isnan(y)) {
-                           if ((denom == 0.0) &&
-                                 (!isnan(a) || !isnan(b))) {
-                                 x = copysign(INFINITY, c) * a;
-                                 y = copysign(INFINITY, c) * b;
-                           }
-                           else if ((isinf(a) || isinf(b)) &&
-                                 isfinite(c) && isfinite(d)) {
-                                 a = copysign(isinf(a) ? 1.0 : 0.0,                        a);
-                                 b = copysign(isinf(b) ? 1.0 : 0.0,                        b);
-                                 x = INFINITY * ( a * c + b * d );
-                                 y = INFINITY * ( b * c - a * d );
-                           }
-                           else if (isinf(logbw) &&
-                                 isfinite(a) && isfinite(b)) {
-                                 c = copysign(isinf(c) ? 1.0 : 0.0,                        c);
-                                 d = copysign(isinf(d) ? 1.0 : 0.0,                        d);
-                                 x = 0.0 * ( a * c + b * d );
-                                 y = 0.0 * ( b * c - a * d );
-
-[page 531] (Contents)
-
-                           }
-                     }
-                     return x + I * y;
-            }
-9   Scaling the denominator alleviates the main overflow and underflow problem, which is more serious than
-    for multiplication. In the spirit of the multiplication example above, this code does not defend against
-    overflow and underflow in the calculation of the numerator. Scaling with the scalbn function, instead of
-    with division, provides better roundoff characteristics.
-
-    G.5.2 Additive operators
-    Semantics
-1   If both operands have imaginary type, then the result has imaginary type. (If one operand
-    has real type and the other operand has imaginary type, or if either operand has complex
-    type, then the result has complex type.)
-2   In all cases the result and floating-point exception behavior of a + or - operator is defined
-    by the usual mathematical formula:
-           + or -              u                       iv                    u + iv
-
-           x                 x(+-)u                     x (+-) iv              (x (+-) u) (+-) iv
-
-           iy               (+-)u + iy                 i(y (+-) v)             (+-)u + i(y (+-) v)
-
-           x + iy         (x (+-) u) + iy            x + i(y (+-) v)        (x (+-) u) + i(y (+-) v)
-    G.6 Complex arithmetic <complex.h>
-1   The macros
-            imaginary
-    and
-            _Imaginary_I
-    are defined, respectively, as _Imaginary and a constant expression of type const
-    float _Imaginary with the value of the imaginary unit. The macro
-            I
-    is defined to be _Imaginary_I (not _Complex_I as stated in 7.3). Notwithstanding
-    the provisions of 7.1.3, a program may undefine and then perhaps redefine the macro
-    imaginary.
-2   This subclause contains specifications for the <complex.h> functions that are
-    particularly suited to IEC 60559 implementations. For families of functions, the
-    specifications apply to all of the functions even though only the principal function is
-
-[page 532] (Contents)
-
-    shown. Unless otherwise specified, where the symbol ''(+-)'' occurs in both an argument
-    and the result, the result has the same sign as the argument.
-3   The functions are continuous onto both sides of their branch cuts, taking into account the
-    sign of zero. For example, csqrt(-2 (+-) i0) = (+-)isqrt:2.  -
-4   Since complex and imaginary values are composed of real values, each function may be
-    regarded as computing real values from real values. Except as noted, the functions treat
-    real infinities, NaNs, signed zeros, subnormals, and the floating-point exception flags in a
-    manner consistent with the specifications for real functions in F.10.359)
-5   The functions cimag, conj, cproj, and creal are fully specified for all
-    implementations, including IEC 60559 ones, in 7.3.9. These functions raise no floating-
-    point exceptions.
-6   Each of the functions cabs and carg is specified by a formula in terms of a real
-    function (whose special cases are covered in annex F):
-            cabs(x + iy) = hypot(x, y)
-            carg(x + iy) = atan2(y, x)
-7   Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by
-    a formula in terms of other complex functions (whose special cases are specified below):
-            casin(z)        =   -i casinh(iz)
-            catan(z)        =   -i catanh(iz)
-            ccos(z)         =   ccosh(iz)
-            csin(z)         =   -i csinh(iz)
-            ctan(z)         =   -i ctanh(iz)
-8   For the other functions, the following subclauses specify behavior for special cases,
-    including treatment of the ''invalid'' and ''divide-by-zero'' floating-point exceptions. For
-    families of functions, the specifications apply to all of the functions even though only the
-    principal function is shown. For a function f satisfying f (conj(z)) = conj( f (z)), the
-    specifications for the upper half-plane imply the specifications for the lower half-plane; if
-    the function f is also either even, f (-z) = f (z), or odd, f (-z) = - f (z), then the
-    specifications for the first quadrant imply the specifications for the other three quadrants.
-9   In the following subclauses, cis(y) is defined as cos(y) + i sin(y).
-
-
-
-
-    359) As noted in G.3, a complex value with at least one infinite part is regarded as an infinity even if its
-         other part is a NaN.
-
-[page 533] (Contents)
-
-    G.6.1 Trigonometric functions
-    G.6.1.1 The cacos functions
-1   -- cacos(conj(z)) = conj(cacos(z)).
-    -- cacos((+-)0 + i0) returns pi /2 - i0.
-    -- cacos((+-)0 + iNaN) returns pi /2 + iNaN.
-    -- cacos(x + i (inf)) returns pi /2 - i (inf), for finite x.
-    -- cacos(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for nonzero finite x.
-    -- cacos(-(inf) + iy) returns pi - i (inf), for positive-signed finite y.
-    -- cacos(+(inf) + iy) returns +0 - i (inf), for positive-signed finite y.
-    -- cacos(-(inf) + i (inf)) returns 3pi /4 - i (inf).
-    -- cacos(+(inf) + i (inf)) returns pi /4 - i (inf).
-    -- cacos((+-)(inf) + iNaN) returns NaN (+-) i (inf) (where the sign of the imaginary part of the
-      result is unspecified).
-    -- cacos(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite y.
-    -- cacos(NaN + i (inf)) returns NaN - i (inf).
-    -- cacos(NaN + iNaN) returns NaN + iNaN.
-    G.6.2 Hyperbolic functions
-    G.6.2.1 The cacosh functions
-1   -- cacosh(conj(z)) = conj(cacosh(z)).
-    -- cacosh((+-)0 + i0) returns +0 + ipi /2.
-    -- cacosh(x + i (inf)) returns +(inf) + ipi /2, for finite x.
-    -- cacosh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid''
-      floating-point exception, for finite x.
-    -- cacosh(-(inf) + iy) returns +(inf) + ipi , for positive-signed finite y.
-    -- cacosh(+(inf) + iy) returns +(inf) + i0, for positive-signed finite y.
-    -- cacosh(-(inf) + i (inf)) returns +(inf) + i3pi /4.
-    -- cacosh(+(inf) + i (inf)) returns +(inf) + ipi /4.
-    -- cacosh((+-)(inf) + iNaN) returns +(inf) + iNaN.
-
-
-[page 534] (Contents)
-
-    -- cacosh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
-      floating-point exception, for finite y.
-    -- cacosh(NaN + i (inf)) returns +(inf) + iNaN.
-    -- cacosh(NaN + iNaN) returns NaN + iNaN.
-    G.6.2.2 The casinh functions
-1   -- casinh(conj(z)) = conj(casinh(z)) and casinh is odd.
-    -- casinh(+0 + i0) returns 0 + i0.
-    -- casinh(x + i (inf)) returns +(inf) + ipi /2 for positive-signed finite x.
-    -- casinh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid''
-      floating-point exception, for finite x.
-    -- casinh(+(inf) + iy) returns +(inf) + i0 for positive-signed finite y.
-    -- casinh(+(inf) + i (inf)) returns +(inf) + ipi /4.
-    -- casinh(+(inf) + iNaN) returns +(inf) + iNaN.
-    -- casinh(NaN + i0) returns NaN + i0.
-    -- casinh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
-      floating-point exception, for finite nonzero y.
-    -- casinh(NaN + i (inf)) returns (+-)(inf) + iNaN (where the sign of the real part of the result
-      is unspecified).
-    -- casinh(NaN + iNaN) returns NaN + iNaN.
-    G.6.2.3 The catanh functions
-1   -- catanh(conj(z)) = conj(catanh(z)) and catanh is odd.
-    -- catanh(+0 + i0) returns +0 + i0.
-    -- catanh(+0 + iNaN) returns +0 + iNaN.
-    -- catanh(+1 + i0) returns +(inf) + i0 and raises the ''divide-by-zero'' floating-point
-      exception.
-    -- catanh(x + i (inf)) returns +0 + ipi /2, for finite positive-signed x.
-    -- catanh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid''
-      floating-point exception, for nonzero finite x.
-    -- catanh(+(inf) + iy) returns +0 + ipi /2, for finite positive-signed y.
-    -- catanh(+(inf) + i (inf)) returns +0 + ipi /2.
-    -- catanh(+(inf) + iNaN) returns +0 + iNaN.
-
-[page 535] (Contents)
-
-    -- catanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
-      floating-point exception, for finite y.
-    -- catanh(NaN + i (inf)) returns (+-)0 + ipi /2 (where the sign of the real part of the result is
-      unspecified).
-    -- catanh(NaN + iNaN) returns NaN + iNaN.
-    G.6.2.4 The ccosh functions
-1   -- ccosh(conj(z)) = conj(ccosh(z)) and ccosh is even.
-    -- ccosh(+0 + i0) returns 1 + i0.
-    -- ccosh(+0 + i (inf)) returns NaN (+-) i0 (where the sign of the imaginary part of the
-      result is unspecified) and raises the ''invalid'' floating-point exception.
-    -- ccosh(+0 + iNaN) returns NaN (+-) i0 (where the sign of the imaginary part of the
-      result is unspecified).
-    -- ccosh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point
-      exception, for finite nonzero x.
-    -- ccosh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite nonzero x.
-    -- ccosh(+(inf) + i0) returns +(inf) + i0.
-    -- ccosh(+(inf) + iy) returns +(inf) cis(y), for finite nonzero y.
-    -- ccosh(+(inf) + i (inf)) returns (+-)(inf) + iNaN (where the sign of the real part of the result is
-      unspecified) and raises the ''invalid'' floating-point exception.
-    -- ccosh(+(inf) + iNaN) returns +(inf) + iNaN.
-    -- ccosh(NaN + i0) returns NaN (+-) i0 (where the sign of the imaginary part of the
-      result is unspecified).
-    -- ccosh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for all nonzero numbers y.
-    -- ccosh(NaN + iNaN) returns NaN + iNaN.
-    G.6.2.5 The csinh functions
-1   -- csinh(conj(z)) = conj(csinh(z)) and csinh is odd.
-    -- csinh(+0 + i0) returns +0 + i0.
-    -- csinh(+0 + i (inf)) returns (+-)0 + iNaN (where the sign of the real part of the result is
-      unspecified) and raises the ''invalid'' floating-point exception.
-    -- csinh(+0 + iNaN) returns (+-)0 + iNaN (where the sign of the real part of the result is
-      unspecified).
-[page 536] (Contents)
-
-    -- csinh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point
-      exception, for positive finite x.
-    -- csinh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite nonzero x.
-    -- csinh(+(inf) + i0) returns +(inf) + i0.
-    -- csinh(+(inf) + iy) returns +(inf) cis(y), for positive finite y.
-    -- csinh(+(inf) + i (inf)) returns (+-)(inf) + iNaN (where the sign of the real part of the result is
-      unspecified) and raises the ''invalid'' floating-point exception.
-    -- csinh(+(inf) + iNaN) returns (+-)(inf) + iNaN (where the sign of the real part of the result
-      is unspecified).
-    -- csinh(NaN + i0) returns NaN + i0.
-    -- csinh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for all nonzero numbers y.
-    -- csinh(NaN + iNaN) returns NaN + iNaN.
-    G.6.2.6 The ctanh functions
-1   -- ctanh(conj(z)) = conj(ctanh(z))and ctanh is odd.
-    -- ctanh(+0 + i0) returns +0 + i0.
-    -- ctanh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point
-      exception, for finite x.
-    -- ctanh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite x.
-    -- ctanh(+(inf) + iy) returns 1 + i0 sin(2y), for positive-signed finite y.
-    -- ctanh(+(inf) + i (inf)) returns 1 (+-) i0 (where the sign of the imaginary part of the result
-      is unspecified).
-    -- ctanh(+(inf) + iNaN) returns 1 (+-) i0 (where the sign of the imaginary part of the
-      result is unspecified).
-    -- ctanh(NaN + i0) returns NaN + i0.
-    -- ctanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for all nonzero numbers y.
-    -- ctanh(NaN + iNaN) returns NaN + iNaN.
-
-
-
-
-[page 537] (Contents)
-
-    G.6.3 Exponential and logarithmic functions
-    G.6.3.1 The cexp functions
-1   -- cexp(conj(z)) = conj(cexp(z)).
-    -- cexp((+-)0 + i0) returns 1 + i0.
-    -- cexp(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point
-      exception, for finite x.
-    -- cexp(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite x.
-    -- cexp(+(inf) + i0) returns +(inf) + i0.
-    -- cexp(-(inf) + iy) returns +0 cis(y), for finite y.
-    -- cexp(+(inf) + iy) returns +(inf) cis(y), for finite nonzero y.
-    -- cexp(-(inf) + i (inf)) returns (+-)0 (+-) i0 (where the signs of the real and imaginary parts of
-      the result are unspecified).
-    -- cexp(+(inf) + i (inf)) returns (+-)(inf) + iNaN and raises the ''invalid'' floating-point
-      exception (where the sign of the real part of the result is unspecified).
-    -- cexp(-(inf) + iNaN) returns (+-)0 (+-) i0 (where the signs of the real and imaginary parts
-      of the result are unspecified).
-    -- cexp(+(inf) + iNaN) returns (+-)(inf) + iNaN (where the sign of the real part of the result
-      is unspecified).
-    -- cexp(NaN + i0) returns NaN + i0.
-    -- cexp(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for all nonzero numbers y.
-    -- cexp(NaN + iNaN) returns NaN + iNaN.
-    G.6.3.2 The clog functions
-1   -- clog(conj(z)) = conj(clog(z)).
-    -- clog(-0 + i0) returns -(inf) + ipi and raises the ''divide-by-zero'' floating-point
-      exception.
-    -- clog(+0 + i0) returns -(inf) + i0 and raises the ''divide-by-zero'' floating-point
-      exception.
-    -- clog(x + i (inf)) returns +(inf) + ipi /2, for finite x.
-    -- clog(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite x.
-
-[page 538] (Contents)
-
-    -- clog(-(inf) + iy) returns +(inf) + ipi , for finite positive-signed y.
-    -- clog(+(inf) + iy) returns +(inf) + i0, for finite positive-signed y.
-    -- clog(-(inf) + i (inf)) returns +(inf) + i3pi /4.
-    -- clog(+(inf) + i (inf)) returns +(inf) + ipi /4.
-    -- clog((+-)(inf) + iNaN) returns +(inf) + iNaN.
-    -- clog(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite y.
-    -- clog(NaN + i (inf)) returns +(inf) + iNaN.
-    -- clog(NaN + iNaN) returns NaN + iNaN.
-    G.6.4 Power and absolute-value functions
-    G.6.4.1 The cpow functions
-1   The cpow functions raise floating-point exceptions if appropriate for the calculation of
-    the parts of the result, and may raise spurious exceptions.360)
-    G.6.4.2 The csqrt functions
-1   -- csqrt(conj(z)) = conj(csqrt(z)).
-    -- csqrt((+-)0 + i0) returns +0 + i0.
-    -- csqrt(x + i (inf)) returns +(inf) + i (inf), for all x (including NaN).
-    -- csqrt(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite x.
-    -- csqrt(-(inf) + iy) returns +0 + i (inf), for finite positive-signed y.
-    -- csqrt(+(inf) + iy) returns +(inf) + i0, for finite positive-signed y.
-    -- csqrt(-(inf) + iNaN) returns NaN (+-) i (inf) (where the sign of the imaginary part of the
-      result is unspecified).
-    -- csqrt(+(inf) + iNaN) returns +(inf) + iNaN.
-    -- csqrt(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
-      point exception, for finite y.
-    -- csqrt(NaN + iNaN) returns NaN + iNaN.
-
-
-
-
-    360) This allows cpow( z , c ) to be implemented as cexp(c      clog( z )) without precluding
-         implementations that treat special cases more carefully.
-
-[page 539] (Contents)
-
-    G.7 Type-generic math <tgmath.h>
-1   Type-generic macros that accept complex arguments also accept imaginary arguments. If
-    an argument is imaginary, the macro expands to an expression whose type is real,
-    imaginary, or complex, as appropriate for the particular function: if the argument is
-    imaginary, then the types of cos, cosh, fabs, carg, cimag, and creal are real; the
-    types of sin, tan, sinh, tanh, asin, atan, asinh, and atanh are imaginary; and
-    the types of the others are complex.
-2   Given an imaginary argument, each of the type-generic macros cos, sin, tan, cosh,
-    sinh, tanh, asin, atan, asinh, atanh is specified by a formula in terms of real
-    functions:
-           cos(iy)      =   cosh(y)
-           sin(iy)      =   i sinh(y)
-           tan(iy)      =   i tanh(y)
-           cosh(iy)     =   cos(y)
-           sinh(iy)     =   i sin(y)
-           tanh(iy)     =   i tan(y)
-           asin(iy)     =   i asinh(y)
-           atan(iy)     =   i atanh(y)
-           asinh(iy)    =   i asin(y)
-           atanh(iy)    =   i atan(y)
-
-
-
-
-[page 540] (Contents)
-
-                                          Annex H
-                                        (informative)
-                        Language independent arithmetic
-    H.1 Introduction
-1   This annex documents the extent to which the C language supports the ISO/IEC 10967-1
-    standard for language-independent arithmetic (LIA-1). LIA-1 is more general than
-    IEC 60559 (annex F) in that it covers integer and diverse floating-point arithmetics.
-    H.2 Types
-1   The relevant C arithmetic types meet the requirements of LIA-1 types if an
-    implementation adds notification of exceptional arithmetic operations and meets the 1
-    unit in the last place (ULP) accuracy requirement (LIA-1 subclause 5.2.8).
-    H.2.1 Boolean type
-1   The LIA-1 data type Boolean is implemented by the C data type bool with values of
-    true and false, all from <stdbool.h>.
-    H.2.2 Integer types
-1   The signed C integer types int, long int, long long int, and the corresponding
-    unsigned types are compatible with LIA-1. If an implementation adds support for the
-    LIA-1 exceptional values ''integer_overflow'' and ''undefined'', then those types are
-    LIA-1 conformant types. C's unsigned integer types are ''modulo'' in the LIA-1 sense
-    in that overflows or out-of-bounds results silently wrap. An implementation that defines
-    signed integer types as also being modulo need not detect integer overflow, in which case,
-    only integer divide-by-zero need be detected.
-2   The parameters for the integer data types can be accessed by the following:
-    maxint        INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX,
-                  ULLONG_MAX
-    minint        INT_MIN, LONG_MIN, LLONG_MIN
-3   The parameter ''bounded'' is always true, and is not provided. The parameter ''minint''
-    is always 0 for the unsigned types, and is not provided for those types.
-
-
-
-
-[page 541] (Contents)
-
-    H.2.2.1 Integer operations
-1   The integer operations on integer types are the following:
-    addI           x + y
-    subI           x - y
-    mulI           x * y
-    divI, divtI    x / y
-    remI, remtI    x % y
-    negI           -x
-    absI           abs(x), labs(x), llabs(x)
-    eqI            x == y
-    neqI           x != y
-    lssI           x < y
-    leqI           x <= y
-    gtrI           x > y
-    geqI           x >= y
-    where x and y are expressions of the same integer type.
-    H.2.3 Floating-point types
-1   The C floating-point types float, double, and long double are compatible with
-    LIA-1. If an implementation adds support for the LIA-1 exceptional values
-    ''underflow'', ''floating_overflow'', and ''"undefined'', then those types are conformant
-    with LIA-1. An implementation that uses IEC 60559 floating-point formats and
-    operations (see annex F) along with IEC 60559 status flags and traps has LIA-1
-    conformant types.
-    H.2.3.1 Floating-point parameters
-1   The parameters for a floating point data type can be accessed by the following:
-    r              FLT_RADIX
-    p              FLT_MANT_DIG, DBL_MANT_DIG, LDBL_MANT_DIG
-    emax           FLT_MAX_EXP, DBL_MAX_EXP, LDBL_MAX_EXP
-    emin           FLT_MIN_EXP, DBL_MIN_EXP, LDBL_MIN_EXP
-2   The derived constants for the floating point types are accessed by the following:
-
-
-[page 542] (Contents)
-
-    fmax          FLT_MAX, DBL_MAX, LDBL_MAX
-    fminN         FLT_MIN, DBL_MIN, LDBL_MIN
-    epsilon       FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON
-    rnd_style     FLT_ROUNDS
-    H.2.3.2 Floating-point operations
-1   The floating-point operations on floating-point types are the following:
-    addF          x + y
-    subF          x - y
-    mulF          x * y
-    divF          x / y
-    negF          -x
-    absF          fabsf(x), fabs(x), fabsl(x)
-    exponentF     1.f+logbf(x), 1.0+logb(x), 1.L+logbl(x)
-    scaleF        scalbnf(x, n), scalbn(x, n), scalbnl(x, n),
-                  scalblnf(x, li), scalbln(x, li), scalblnl(x, li)
-    intpartF      modff(x, &y), modf(x, &y), modfl(x, &y)
-    fractpartF    modff(x, &y), modf(x, &y), modfl(x, &y)
-    eqF           x == y
-    neqF          x != y
-    lssF          x < y
-    leqF          x <= y
-    gtrF          x > y
-    geqF          x >= y
-    where x and y are expressions of the same floating point type, n is of type int, and li
-    is of type long int.
-    H.2.3.3 Rounding styles
-1   The C Standard requires all floating types to use the same radix and rounding style, so
-    that only one identifier for each is provided to map to LIA-1.
-2   The FLT_ROUNDS parameter can be used to indicate the LIA-1 rounding styles:
-    truncate      FLT_ROUNDS == 0
-
-
-[page 543] (Contents)
-
-    nearest       FLT_ROUNDS == 1
-    other         FLT_ROUNDS != 0 && FLT_ROUNDS != 1
-    provided that an implementation extends FLT_ROUNDS to cover the rounding style used
-    in all relevant LIA-1 operations, not just addition as in C.
-    H.2.4 Type conversions
-1   The LIA-1 type conversions are the following type casts:
-    cvtI' (->) I     (int)i, (long int)i, (long long int)i,
-                  (unsigned int)i, (unsigned long int)i,
-                  (unsigned long long int)i
-    cvtF (->) I      (int)x, (long int)x, (long long int)x,
-                  (unsigned int)x, (unsigned long int)x,
-                  (unsigned long long int)x
-    cvtI (->) F      (float)i, (double)i, (long double)i
-    cvtF' (->) F     (float)x, (double)x, (long double)x
-2   In the above conversions from floating to integer, the use of (cast)x can be replaced with
-    (cast)round(x), (cast)rint(x), (cast)nearbyint(x), (cast)trunc(x),
-    (cast)ceil(x), or (cast)floor(x). In addition, C's floating-point to integer
-    conversion functions, lrint(), llrint(), lround(), and llround(), can be
-    used. They all meet LIA-1's requirements on floating to integer rounding for in-range
-    values. For out-of-range values, the conversions shall silently wrap for the modulo types.
-3   The fmod() function is useful for doing silent wrapping to unsigned integer types, e.g.,
-    fmod( fabs(rint(x)), 65536.0 ) or (0.0 <= (y = fmod( rint(x),
-    65536.0 )) ? y : 65536.0 + y) will compute an integer value in the range 0.0
-    to 65535.0 which can then be cast to unsigned short int. But, the
-    remainder() function is not useful for doing silent wrapping to signed integer types,
-    e.g., remainder( rint(x), 65536.0 ) will compute an integer value in the
-    range -32767.0 to +32768.0 which is not, in general, in the range of signed short
-    int.
-4   C's conversions (casts) from floating-point to floating-point can meet LIA-1
-    requirements if an implementation uses round-to-nearest (IEC 60559 default).
-5   C's conversions (casts) from integer to floating-point can meet LIA-1 requirements if an
-    implementation uses round-to-nearest.
-
-
-
-
-[page 544] (Contents)
-
-    H.3 Notification
-1   Notification is the process by which a user or program is informed that an exceptional
-    arithmetic operation has occurred. C's operations are compatible with LIA-1 in that C
-    allows an implementation to cause a notification to occur when any arithmetic operation
-    returns an exceptional value as defined in LIA-1 clause 5.
-    H.3.1 Notification alternatives
-1   LIA-1 requires at least the following two alternatives for handling of notifications:
-    setting indicators or trap-and-terminate. LIA-1 allows a third alternative: trap-and-
-    resume.
-2   An implementation need only support a given notification alternative for the entire
-    program. An implementation may support the ability to switch between notification
-    alternatives during execution, but is not required to do so. An implementation can
-    provide separate selection for each kind of notification, but this is not required.
-3   C allows an implementation to provide notification. C's SIGFPE (for traps) and
-    FE_INVALID, FE_DIVBYZERO, FE_OVERFLOW, FE_UNDERFLOW (for indicators)
-    can provide LIA-1 notification.
-4   C's signal handlers are compatible with LIA-1. Default handling of SIGFPE can
-    provide trap-and-terminate behavior, except for those LIA-1 operations implemented by
-    math library function calls. User-provided signal handlers for SIGFPE allow for trap-
-    and-resume behavior with the same constraint.
-    H.3.1.1 Indicators
-1   C's <fenv.h> status flags are compatible with the LIA-1 indicators.
-2   The following mapping is for floating-point types:
-    undefined                FE_INVALID, FE_DIVBYZERO
-    floating_overflow         FE_OVERFLOW
-    underflow                FE_UNDERFLOW
-3   The floating-point indicator interrogation and manipulation operations are:
-    set_indicators          feraiseexcept(i)
-    clear_indicators        feclearexcept(i)
-    test_indicators         fetestexcept(i)
-    current_indicators      fetestexcept(FE_ALL_EXCEPT)
-    where i is an expression of type int representing a subset of the LIA-1 indicators.
-4   C allows an implementation to provide the following LIA-1 required behavior: at
-    program termination if any indicator is set the implementation shall send an unambiguous
-[page 545] (Contents)
-
-    and ''hard to ignore'' message (see LIA-1 subclause 6.1.2)
-5   LIA-1 does not make the distinction between floating-point and integer for ''undefined''.
-    This documentation makes that distinction because <fenv.h> covers only the floating-
-    point indicators.
-    H.3.1.2 Traps
-1   C is compatible with LIA-1's trap requirements for arithmetic operations, but not for
-    math library functions (which are not permitted to invoke a user's signal handler for
-    SIGFPE). An implementation can provide an alternative of notification through
-    termination with a ''hard-to-ignore'' message (see LIA-1 subclause 6.1.3).
-2   LIA-1 does not require that traps be precise.
-3   C does require that SIGFPE be the signal corresponding to arithmetic exceptions, if there
-    is any signal raised for them.
-4   C supports signal handlers for SIGFPE and allows trapping of arithmetic exceptions.
-    When arithmetic exceptions do trap, C's signal-handler mechanism allows trap-and-
-    terminate (either default implementation behavior or user replacement for it) or trap-and-
-    resume, at the programmer's option.
-
-
-
-
-[page 546] (Contents)
-
-                                           Annex I
-                                        (informative)
-                                   Common warnings
-1   An implementation may generate warnings in many situations, none of which are
-    specified as part of this International Standard. The following are a few of the more
-    common situations.
-2   -- A new struct or union type appears in a function prototype (6.2.1, 6.7.2.3).
-    -- A block with initialization of an object that has automatic storage duration is jumped
-      into (6.2.4).
-    -- An implicit narrowing conversion is encountered, such as the assignment of a long
-      int or a double to an int, or a pointer to void to a pointer to any type other than
-      a character type (6.3).
-    -- A hexadecimal floating constant cannot be represented exactly in its evaluation format
-      (6.4.4.2).
-    -- An integer character constant includes more than one character or a wide character
-      constant includes more than one multibyte character (6.4.4.4).
-    -- The characters /* are found in a comment (6.4.7).
-    -- An ''unordered'' binary operator (not comma, &&, or ||) contains a side effect to an
-      lvalue in one operand, and a side effect to, or an access to the value of, the identical
-      lvalue in the other operand (6.5).
-    -- A function is called but no prototype has been supplied (6.5.2.2).
-    -- The arguments in a function call do not agree in number and type with those of the
-      parameters in a function definition that is not a prototype (6.5.2.2).
-    -- An object is defined but not used (6.7).
-    -- A value is given to an object of an enumerated type other than by assignment of an
-      enumeration constant that is a member of that type, or an enumeration object that has
-      the same type, or the value of a function that returns the same enumerated type
-      (6.7.2.2).
-    -- An aggregate has a partly bracketed initialization (6.7.8).
-    -- A statement cannot be reached (6.8).
-    -- A statement with no apparent effect is encountered (6.8).
-    -- A constant expression is used as the controlling expression of a selection statement
-      (6.8.4).
-[page 547] (Contents)
-
--- An incorrectly formed preprocessing group is encountered while skipping a
-  preprocessing group (6.10.1).
--- An unrecognized #pragma directive is encountered (6.10.6).
-
-
-
-
-[page 548] (Contents)
-
-                                            Annex J
-                                         (informative)
-                                      Portability issues
-1   This annex collects some information about portability that appears in this International
-    Standard.
-    J.1 Unspecified behavior
-1   The following are unspecified:
-    -- The manner and timing of static initialization (5.1.2).
-    -- The termination status returned to the hosted environment if the return type of main
-      is not compatible with int (5.1.2.2.3).
-    -- The behavior of the display device if a printing character is written when the active
-      position is at the final position of a line (5.2.2).
-    -- The behavior of the display device if a backspace character is written when the active
-      position is at the initial position of a line (5.2.2).
-    -- The behavior of the display device if a horizontal tab character is written when the
-      active position is at or past the last defined horizontal tabulation position (5.2.2).
-    -- The behavior of the display device if a vertical tab character is written when the active
-      position is at or past the last defined vertical tabulation position (5.2.2).
-    -- How an extended source character that does not correspond to a universal character
-      name counts toward the significant initial characters in an external identifier (5.2.4.1).
-    -- Many aspects of the representations of types (6.2.6).
-    -- The value of padding bytes when storing values in structures or unions (6.2.6.1).
-    -- The values of bytes that correspond to union members other than the one last stored
-      into (6.2.6.1).
-    -- The representation used when storing a value in an object that has more than one
-      object representation for that value (6.2.6.1).
-    -- The values of any padding bits in integer representations (6.2.6.2).
-    -- Whether certain operators can generate negative zeros and whether a negative zero
-      becomes a normal zero when stored in an object (6.2.6.2).
-    -- Whether two string literals result in distinct arrays (6.4.5).
-    -- The order in which subexpressions are evaluated and the order in which side effects
-      take place, except as specified for the function-call (), &&, ||, ? :, and comma
-[page 549] (Contents)
-
-      operators (6.5).
--- The order in which the function designator, arguments, and subexpressions within the
-  arguments are evaluated in a function call (6.5.2.2).
--- The order of side effects among compound literal initialization list expressions
-  (6.5.2.5).
--- The order in which the operands of an assignment operator are evaluated (6.5.16).
--- The alignment of the addressable storage unit allocated to hold a bit-field (6.7.2.1).
--- Whether a call to an inline function uses the inline definition or the external definition
-  of the function (6.7.4).
--- Whether or not a size expression is evaluated when it is part of the operand of a
-  sizeof operator and changing the value of the size expression would not affect the
-  result of the operator (6.7.6.2).
--- The order in which any side effects occur among the initialization list expressions in
-  an initializer (6.7.9).
--- The layout of storage for function parameters (6.9.1).
--- When a fully expanded macro replacement list contains a function-like macro name
-  as its last preprocessing token and the next preprocessing token from the source file is
-  a (, and the fully expanded replacement of that macro ends with the name of the first
-  macro and the next preprocessing token from the source file is again a (, whether that
-  is considered a nested replacement (6.10.3).
--- The order in which # and ## operations are evaluated during macro substitution
-  (6.10.3.2, 6.10.3.3).
--- The state of the floating-point status flags when execution passes from a part of the
-  program translated with FENV_ACCESS ''off'' to a part translated with
-  FENV_ACCESS ''on'' (7.6.1).
--- The order in which feraiseexcept raises floating-point exceptions, except as
-  stated in F.8.6 (7.6.2.3).
--- Whether math_errhandling is a macro or an identifier with external linkage
-  (7.12).
--- The results of the frexp functions when the specified value is not a floating-point
-  number (7.12.6.4).
--- The numeric result of the ilogb functions when the correct value is outside the
-  range of the return type (7.12.6.5, F.10.3.5).
--- The result of rounding when the value is out of range (7.12.9.5, 7.12.9.7, F.10.6.5).
-
-
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-
--- The value stored by the remquo functions in the object pointed to by quo when y is
-  zero (7.12.10.3).
--- Whether a comparison macro argument that is represented in a format wider than its
-  semantic type is converted to the semantic type (7.12.14).
--- Whether setjmp is a macro or an identifier with external linkage (7.13).
--- Whether va_copy and va_end are macros or identifiers with external linkage
-  (7.16.1).
--- The hexadecimal digit before the decimal point when a non-normalized floating-point
-  number is printed with an a or A conversion specifier (7.21.6.1, 7.28.2.1).
--- The value of the file position indicator after a successful call to the ungetc function
-  for a text stream, or the ungetwc function for any stream, until all pushed-back
-  characters are read or discarded (7.21.7.10, 7.28.3.10).
--- The details of the value stored by the fgetpos function (7.21.9.1).
--- The details of the value returned by the ftell function for a text stream (7.21.9.4).
--- Whether the strtod, strtof, strtold, wcstod, wcstof, and wcstold
-  functions convert a minus-signed sequence to a negative number directly or by
-  negating the value resulting from converting the corresponding unsigned sequence
-  (7.22.1.3, 7.28.4.1.1).
--- The order and contiguity of storage allocated by successive calls to the calloc,
-  malloc, and realloc functions (7.22.3).
--- The amount of storage allocated by a successful call to the calloc, malloc, or
-  realloc function when 0 bytes was requested (7.22.3).
--- Which of two elements that compare as equal is matched by the bsearch function
-  (7.22.5.1).
--- The order of two elements that compare as equal in an array sorted by the qsort
-  function (7.22.5.2).
--- The encoding of the calendar time returned by the time function (7.26.2.4).
--- The characters stored by the strftime or wcsftime function if any of the time
-  values being converted is outside the normal range (7.26.3.5, 7.28.5.1).
--- The conversion state after an encoding error occurs (7.28.6.3.2, 7.28.6.3.3, 7.28.6.4.1,
-  7.28.6.4.2,
--- The resulting value when the ''invalid'' floating-point exception is raised during
-  IEC 60559 floating to integer conversion (F.4).
-
-
-
-[page 551] (Contents)
-
-    -- Whether conversion of non-integer IEC 60559 floating values to integer raises the
-      ''inexact'' floating-point exception (F.4).
-    -- Whether or when library functions in <math.h> raise the ''inexact'' floating-point
-      exception in an IEC 60559 conformant implementation (F.10).
-    -- Whether or when library functions in <math.h> raise an undeserved ''underflow''
-      floating-point exception in an IEC 60559 conformant implementation (F.10).
-    -- The exponent value stored by frexp for a NaN or infinity (F.10.3.4).
-    -- The numeric result returned by the lrint, llrint, lround, and llround
-      functions if the rounded value is outside the range of the return type (F.10.6.5,
-      F.10.6.7).
-    -- The sign of one part of the complex result of several math functions for certain
-      exceptional values in IEC 60559 compatible implementations (G.6.1.1, G.6.2.2,
-      G.6.2.3, G.6.2.4, G.6.2.5, G.6.2.6, G.6.3.1, G.6.4.2).
-    J.2 Undefined behavior
-1   The behavior is undefined in the following circumstances:
-    -- A ''shall'' or ''shall not'' requirement that appears outside of a constraint is violated
-      (clause 4).
-    -- A nonempty source file does not end in a new-line character which is not immediately
-      preceded by a backslash character or ends in a partial preprocessing token or
-      comment (5.1.1.2).
-    -- Token concatenation produces a character sequence matching the syntax of a
-      universal character name (5.1.1.2).
-    -- A program in a hosted environment does not define a function named main using one
-      of the specified forms (5.1.2.2.1).
-    -- The execution of a program contains a data race (5.1.2.4).
-    -- A character not in the basic source character set is encountered in a source file, except
-      in an identifier, a character constant, a string literal, a header name, a comment, or a
-      preprocessing token that is never converted to a token (5.2.1).
-    -- An identifier, comment, string literal, character constant, or header name contains an
-      invalid multibyte character or does not begin and end in the initial shift state (5.2.1.2).
-    -- The same identifier has both internal and external linkage in the same translation unit
-      (6.2.2).
-    -- An object is referred to outside of its lifetime (6.2.4).
-
-
-
-[page 552] (Contents)
-
--- The value of a pointer to an object whose lifetime has ended is used (6.2.4).
--- The value of an object with automatic storage duration is used while it is
-  indeterminate (6.2.4, 6.7.9, 6.8).
--- A trap representation is read by an lvalue expression that does not have character type
-  (6.2.6.1).
--- A trap representation is produced by a side effect that modifies any part of the object
-  using an lvalue expression that does not have character type (6.2.6.1).
--- The operands to certain operators are such that they could produce a negative zero
-  result, but the implementation does not support negative zeros (6.2.6.2).
--- Two declarations of the same object or function specify types that are not compatible
-  (6.2.7).
--- A program requires the formation of a composite type from a variable length array
-  type whose size is specified by an expression that is not evaluated (6.2.7).
--- Conversion to or from an integer type produces a value outside the range that can be
-  represented (6.3.1.4).
--- Demotion of one real floating type to another produces a value outside the range that
-  can be represented (6.3.1.5).
--- An lvalue does not designate an object when evaluated (6.3.2.1).
--- A non-array lvalue with an incomplete type is used in a context that requires the value
-  of the designated object (6.3.2.1).
--- An lvalue designating an object of automatic storage duration that could have been
-  declared with the register storage class is used in a context that requires the value
-  of the designated object, but the object is uninitialized. (6.3.2.1).
--- An lvalue having array type is converted to a pointer to the initial element of the
-  array, and the array object has register storage class (6.3.2.1).
--- An attempt is made to use the value of a void expression, or an implicit or explicit
-  conversion (except to void) is applied to a void expression (6.3.2.2).
--- Conversion of a pointer to an integer type produces a value outside the range that can
-  be represented (6.3.2.3).
--- Conversion between two pointer types produces a result that is incorrectly aligned
-  (6.3.2.3).
--- A pointer is used to call a function whose type is not compatible with the referenced
-  type (6.3.2.3).
-
-
-
-[page 553] (Contents)
-
--- An unmatched ' or " character is encountered on a logical source line during
-  tokenization (6.4).
--- A reserved keyword token is used in translation phase 7 or 8 for some purpose other
-  than as a keyword (6.4.1).
--- A universal character name in an identifier does not designate a character whose
-  encoding falls into one of the specified ranges (6.4.2.1).
--- The initial character of an identifier is a universal character name designating a digit
-  (6.4.2.1).
--- Two identifiers differ only in nonsignificant characters (6.4.2.1).
--- The identifier __func__ is explicitly declared (6.4.2.2).
--- The program attempts to modify a string literal (6.4.5).
--- The characters ', \, ", //, or /* occur in the sequence between the < and >
-  delimiters, or the characters ', \, //, or /* occur in the sequence between the "
-  delimiters, in a header name preprocessing token (6.4.7).
--- A side effect on a scalar object is unsequenced relative to either a different side effect
-  on the same scalar object or a value computation using the value of the same scalar
-  object (6.5).
--- An exceptional condition occurs during the evaluation of an expression (6.5).
--- An object has its stored value accessed other than by an lvalue of an allowable type
-  (6.5).
--- For a call to a function without a function prototype in scope, the number of
-  arguments does not equal the number of parameters (6.5.2.2).
--- For call to a function without a function prototype in scope where the function is
-  defined with a function prototype, either the prototype ends with an ellipsis or the
-  types of the arguments after promotion are not compatible with the types of the
-  parameters (6.5.2.2).
--- For a call to a function without a function prototype in scope where the function is not
-  defined with a function prototype, the types of the arguments after promotion are not
-  compatible with those of the parameters after promotion (with certain exceptions)
-  (6.5.2.2).
--- A function is defined with a type that is not compatible with the type (of the
-  expression) pointed to by the expression that denotes the called function (6.5.2.2).
--- A member of an _Atomic-qualified structure or union is accessed (6.5.2.3).
--- The operand of the unary * operator has an invalid value (6.5.3.2).
-
-
-[page 554] (Contents)
-
--- A pointer is converted to other than an integer or pointer type (6.5.4).
--- The value of the second operand of the / or % operator is zero (6.5.5).
--- Addition or subtraction of a pointer into, or just beyond, an array object and an
-  integer type produces a result that does not point into, or just beyond, the same array
-  object (6.5.6).
--- Addition or subtraction of a pointer into, or just beyond, an array object and an
-  integer type produces a result that points just beyond the array object and is used as
-  the operand of a unary * operator that is evaluated (6.5.6).
--- Pointers that do not point into, or just beyond, the same array object are subtracted
-  (6.5.6).
--- An array subscript is out of range, even if an object is apparently accessible with the
-  given subscript (as in the lvalue expression a[1][7] given the declaration int
-  a[4][5]) (6.5.6).
--- The result of subtracting two pointers is not representable in an object of type
-  ptrdiff_t (6.5.6).
--- An expression is shifted by a negative number or by an amount greater than or equal
-  to the width of the promoted expression (6.5.7).
--- An expression having signed promoted type is left-shifted and either the value of the
-  expression is negative or the result of shifting would be not be representable in the
-  promoted type (6.5.7).
--- Pointers that do not point to the same aggregate or union (nor just beyond the same
-  array object) are compared using relational operators (6.5.8).
--- An object is assigned to an inexactly overlapping object or to an exactly overlapping
-  object with incompatible type (6.5.16.1).
--- An expression that is required to be an integer constant expression does not have an
-  integer type; has operands that are not integer constants, enumeration constants,
-  character constants, sizeof expressions whose results are integer constants, or
-  immediately-cast floating constants; or contains casts (outside operands to sizeof
-  operators) other than conversions of arithmetic types to integer types (6.6).
--- A constant expression in an initializer is not, or does not evaluate to, one of the
-  following: an arithmetic constant expression, a null pointer constant, an address
-  constant, or an address constant for a complete object type plus or minus an integer
-  constant expression (6.6).
--- An arithmetic constant expression does not have arithmetic type; has operands that
-  are not integer constants, floating constants, enumeration constants, character
-  constants, or sizeof expressions; or contains casts (outside operands to sizeof
-
-[page 555] (Contents)
-
-   operators) other than conversions of arithmetic types to arithmetic types (6.6).
--- The value of an object is accessed by an array-subscript [], member-access . or ->,
-  address &, or indirection * operator or a pointer cast in creating an address constant
-  (6.6).
--- An identifier for an object is declared with no linkage and the type of the object is
-  incomplete after its declarator, or after its init-declarator if it has an initializer (6.7).
--- A function is declared at block scope with an explicit storage-class specifier other
-  than extern (6.7.1).
--- A structure or union is defined as containing no named members, no anonymous
-  structures, and no anonymous unions (6.7.2.1).
--- An attempt is made to access, or generate a pointer to just past, a flexible array
-  member of a structure when the referenced object provides no elements for that array
-  (6.7.2.1).
--- When the complete type is needed, an incomplete structure or union type is not
-  completed in the same scope by another declaration of the tag that defines the content
-  (6.7.2.3).
--- An attempt is made to modify an object defined with a const-qualified type through
-  use of an lvalue with non-const-qualified type (6.7.3).
--- An attempt is made to refer to an object defined with a volatile-qualified type through
-  use of an lvalue with non-volatile-qualified type (6.7.3).
--- An attempt is made to refer to an object defined with an _Atomic-qualified type
-  through use of an lvalue with non-_Atomic-qualified type (6.7.3).
--- The specification of a function type includes any type qualifiers (6.7.3).
--- Two qualified types that are required to be compatible do not have the identically
-  qualified version of a compatible type (6.7.3).
--- An object which has been modified is accessed through a restrict-qualified pointer to
-  a const-qualified type, or through a restrict-qualified pointer and another pointer that
-  are not both based on the same object (6.7.3.1).
--- A restrict-qualified pointer is assigned a value based on another restricted pointer
-  whose associated block neither began execution before the block associated with this
-  pointer, nor ended before the assignment (6.7.3.1).
--- A function with external linkage is declared with an inline function specifier, but is
-  not also defined in the same translation unit (6.7.4).
--- A function declared with a _Noreturn function specifier returns to its caller (6.7.4).
-
-
-[page 556] (Contents)
-
--- The definition of an object has an alignment specifier and another declaration of that
-  object has a different alignment specifier (6.7.5).
--- Declarations of an object in different translation units have different alignment
-  specifiers (6.7.5).
--- Two pointer types that are required to be compatible are not identically qualified, or
-  are not pointers to compatible types (6.7.6.1).
--- The size expression in an array declaration is not a constant expression and evaluates
-  at program execution time to a nonpositive value (6.7.6.2).
--- In a context requiring two array types to be compatible, they do not have compatible
-  element types, or their size specifiers evaluate to unequal values (6.7.6.2).
--- A declaration of an array parameter includes the keyword static within the [ and
-  ] and the corresponding argument does not provide access to the first element of an
-  array with at least the specified number of elements (6.7.6.3).
--- A storage-class specifier or type qualifier modifies the keyword void as a function
-  parameter type list (6.7.6.3).
--- In a context requiring two function types to be compatible, they do not have
-  compatible return types, or their parameters disagree in use of the ellipsis terminator
-  or the number and type of parameters (after default argument promotion, when there
-  is no parameter type list or when one type is specified by a function definition with an
-  identifier list) (6.7.6.3).
--- The value of an unnamed member of a structure or union is used (6.7.9).
--- The initializer for a scalar is neither a single expression nor a single expression
-  enclosed in braces (6.7.9).
--- The initializer for a structure or union object that has automatic storage duration is
-  neither an initializer list nor a single expression that has compatible structure or union
-  type (6.7.9).
--- The initializer for an aggregate or union, other than an array initialized by a string
-  literal, is not a brace-enclosed list of initializers for its elements or members (6.7.9).
--- An identifier with external linkage is used, but in the program there does not exist
-  exactly one external definition for the identifier, or the identifier is not used and there
-  exist multiple external definitions for the identifier (6.9).
--- A function definition includes an identifier list, but the types of the parameters are not
-  declared in a following declaration list (6.9.1).
--- An adjusted parameter type in a function definition is not a complete object type
-  (6.9.1).
-
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-
--- A function that accepts a variable number of arguments is defined without a
-  parameter type list that ends with the ellipsis notation (6.9.1).
--- The } that terminates a function is reached, and the value of the function call is used
-  by the caller (6.9.1).
--- An identifier for an object with internal linkage and an incomplete type is declared
-  with a tentative definition (6.9.2).
--- The token defined is generated during the expansion of a #if or #elif
-  preprocessing directive, or the use of the defined unary operator does not match
-  one of the two specified forms prior to macro replacement (6.10.1).
--- The #include preprocessing directive that results after expansion does not match
-  one of the two header name forms (6.10.2).
--- The character sequence in an #include preprocessing directive does not start with a
-  letter (6.10.2).
--- There are sequences of preprocessing tokens within the list of macro arguments that
-  would otherwise act as preprocessing directives (6.10.3).
--- The result of the preprocessing operator # is not a valid character string literal
-  (6.10.3.2).
--- The result of the preprocessing operator ## is not a valid preprocessing token
-  (6.10.3.3).
--- The #line preprocessing directive that results after expansion does not match one of
-  the two well-defined forms, or its digit sequence specifies zero or a number greater
-  than 2147483647 (6.10.4).
--- A non-STDC #pragma preprocessing directive that is documented as causing
-  translation failure or some other form of undefined behavior is encountered (6.10.6).
--- A #pragma STDC preprocessing directive does not match one of the well-defined
-  forms (6.10.6).
--- The name of a predefined macro, or the identifier defined, is the subject of a
-  #define or #undef preprocessing directive (6.10.8).
--- An attempt is made to copy an object to an overlapping object by use of a library
-  function, other than as explicitly allowed (e.g., memmove) (clause 7).
--- A file with the same name as one of the standard headers, not provided as part of the
-  implementation, is placed in any of the standard places that are searched for included
-  source files (7.1.2).
--- A header is included within an external declaration or definition (7.1.2).
-
-
-[page 558] (Contents)
-
--- A function, object, type, or macro that is specified as being declared or defined by
-  some standard header is used before any header that declares or defines it is included
-  (7.1.2).
--- A standard header is included while a macro is defined with the same name as a
-  keyword (7.1.2).
--- The program attempts to declare a library function itself, rather than via a standard
-  header, but the declaration does not have external linkage (7.1.2).
--- The program declares or defines a reserved identifier, other than as allowed by 7.1.4
-  (7.1.3).
--- The program removes the definition of a macro whose name begins with an
-  underscore and either an uppercase letter or another underscore (7.1.3).
--- An argument to a library function has an invalid value or a type not expected by a
-  function with variable number of arguments (7.1.4).
--- The pointer passed to a library function array parameter does not have a value such
-  that all address computations and object accesses are valid (7.1.4).
--- The macro definition of assert is suppressed in order to access an actual function
-  (7.2).
--- The argument to the assert macro does not have a scalar type (7.2).
--- The CX_LIMITED_RANGE, FENV_ACCESS, or FP_CONTRACT pragma is used in
-  any context other than outside all external declarations or preceding all explicit
-  declarations and statements inside a compound statement (7.3.4, 7.6.1, 7.12.2).
--- The value of an argument to a character handling function is neither equal to the value
-  of EOF nor representable as an unsigned char (7.4).
--- A macro definition of errno is suppressed in order to access an actual object, or the
-  program defines an identifier with the name errno (7.5).
--- Part of the program tests floating-point status flags, sets floating-point control modes,
-  or runs under non-default mode settings, but was translated with the state for the
-  FENV_ACCESS pragma ''off'' (7.6.1).
--- The exception-mask argument for one of the functions that provide access to the
-  floating-point status flags has a nonzero value not obtained by bitwise OR of the
-  floating-point exception macros (7.6.2).
--- The fesetexceptflag function is used to set floating-point status flags that were
-  not specified in the call to the fegetexceptflag function that provided the value
-  of the corresponding fexcept_t object (7.6.2.4).
-
-
-
-[page 559] (Contents)
-
--- The argument to fesetenv or feupdateenv is neither an object set by a call to
-  fegetenv or feholdexcept, nor is it an environment macro (7.6.4.3, 7.6.4.4).
--- The value of the result of an integer arithmetic or conversion function cannot be
-  represented (7.8.2.1, 7.8.2.2, 7.8.2.3, 7.8.2.4, 7.22.6.1, 7.22.6.2, 7.22.1).
--- The program modifies the string pointed to by the value returned by the setlocale
-  function (7.11.1.1).
--- The program modifies the structure pointed to by the value returned by the
-  localeconv function (7.11.2.1).
--- A macro definition of math_errhandling is suppressed or the program defines
-  an identifier with the name math_errhandling (7.12).
--- An argument to a floating-point classification or comparison macro is not of real
-  floating type (7.12.3, 7.12.14).
--- A macro definition of setjmp is suppressed in order to access an actual function, or
-  the program defines an external identifier with the name setjmp (7.13).
--- An invocation of the setjmp macro occurs other than in an allowed context
-  (7.13.2.1).
--- The longjmp function is invoked to restore a nonexistent environment (7.13.2.1).
--- After a longjmp, there is an attempt to access the value of an object of automatic
-  storage duration that does not have volatile-qualified type, local to the function
-  containing the invocation of the corresponding setjmp macro, that was changed
-  between the setjmp invocation and longjmp call (7.13.2.1).
--- The program specifies an invalid pointer to a signal handler function (7.14.1.1).
--- A signal handler returns when the signal corresponded to a computational exception
-  (7.14.1.1).
--- A signal occurs as the result of calling the abort or raise function, and the signal
-  handler calls the raise function (7.14.1.1).
--- A signal occurs other than as the result of calling the abort or raise function, and
-  the signal handler refers to an object with static storage duration other than by
-  assigning a value to an object declared as volatile sig_atomic_t, or calls any
-  function in the standard library other than the abort function, the _Exit function,
-  the quick_exit function, or the signal function (for the same signal number)
-  (7.14.1.1).
--- The value of errno is referred to after a signal occurred other than as the result of
-  calling the abort or raise function and the corresponding signal handler obtained
-  a SIG_ERR return from a call to the signal function (7.14.1.1).
-
-[page 560] (Contents)
-
--- A signal is generated by an asynchronous signal handler (7.14.1.1).
--- A function with a variable number of arguments attempts to access its varying
-  arguments other than through a properly declared and initialized va_list object, or
-  before the va_start macro is invoked (7.16, 7.16.1.1, 7.16.1.4).
--- The macro va_arg is invoked using the parameter ap that was passed to a function
-  that invoked the macro va_arg with the same parameter (7.16).
--- A macro definition of va_start, va_arg, va_copy, or va_end is suppressed in
-  order to access an actual function, or the program defines an external identifier with
-  the name va_copy or va_end (7.16.1).
--- The va_start or va_copy macro is invoked without a corresponding invocation
-  of the va_end macro in the same function, or vice versa (7.16.1, 7.16.1.2, 7.16.1.3,
-  7.16.1.4).
--- The type parameter to the va_arg macro is not such that a pointer to an object of
-  that type can be obtained simply by postfixing a * (7.16.1.1).
--- The va_arg macro is invoked when there is no actual next argument, or with a
-  specified type that is not compatible with the promoted type of the actual next
-  argument, with certain exceptions (7.16.1.1).
--- The va_copy or va_start macro is called to initialize a va_list that was
-  previously initialized by either macro without an intervening invocation of the
-  va_end macro for the same va_list (7.16.1.2, 7.16.1.4).
--- The parameter parmN of a va_start macro is declared with the register
-  storage class, with a function or array type, or with a type that is not compatible with
-  the type that results after application of the default argument promotions (7.16.1.4).
--- The member designator parameter of an offsetof macro is an invalid right
-  operand of the . operator for the type parameter, or designates a bit-field (7.19).
--- The argument in an instance of one of the integer-constant macros is not a decimal,
-  octal, or hexadecimal constant, or it has a value that exceeds the limits for the
-  corresponding type (7.20.4).
--- A byte input/output function is applied to a wide-oriented stream, or a wide character
-  input/output function is applied to a byte-oriented stream (7.21.2).
--- Use is made of any portion of a file beyond the most recent wide character written to
-  a wide-oriented stream (7.21.2).
--- The value of a pointer to a FILE object is used after the associated file is closed
-  (7.21.3).
--- The stream for the fflush function points to an input stream or to an update stream
-    in which the most recent operation was input (7.21.5.2).
-[page 561] (Contents)
-
--- The string pointed to by the mode argument in a call to the fopen function does not
-  exactly match one of the specified character sequences (7.21.5.3).
--- An output operation on an update stream is followed by an input operation without an
-  intervening call to the fflush function or a file positioning function, or an input
-  operation on an update stream is followed by an output operation with an intervening
-  call to a file positioning function (7.21.5.3).
--- An attempt is made to use the contents of the array that was supplied in a call to the
-  setvbuf function (7.21.5.6).
--- There are insufficient arguments for the format in a call to one of the formatted
-  input/output functions, or an argument does not have an appropriate type (7.21.6.1,
-  7.21.6.2, 7.28.2.1, 7.28.2.2).
--- The format in a call to one of the formatted input/output functions or to the
-  strftime or wcsftime function is not a valid multibyte character sequence that
-  begins and ends in its initial shift state (7.21.6.1, 7.21.6.2, 7.26.3.5, 7.28.2.1, 7.28.2.2,
-  7.28.5.1).
--- In a call to one of the formatted output functions, a precision appears with a
-  conversion specifier other than those described (7.21.6.1, 7.28.2.1).
--- A conversion specification for a formatted output function uses an asterisk to denote
-  an argument-supplied field width or precision, but the corresponding argument is not
-  provided (7.21.6.1, 7.28.2.1).
--- A conversion specification for a formatted output function uses a # or 0 flag with a
-  conversion specifier other than those described (7.21.6.1, 7.28.2.1).
--- A conversion specification for one of the formatted input/output functions uses a
-  length modifier with a conversion specifier other than those described (7.21.6.1,
-  7.21.6.2, 7.28.2.1, 7.28.2.2).
--- An s conversion specifier is encountered by one of the formatted output functions,
-  and the argument is missing the null terminator (unless a precision is specified that
-  does not require null termination) (7.21.6.1, 7.28.2.1).
--- An n conversion specification for one of the formatted input/output functions includes
-  any flags, an assignment-suppressing character, a field width, or a precision (7.21.6.1,
-  7.21.6.2, 7.28.2.1, 7.28.2.2).
--- A % conversion specifier is encountered by one of the formatted input/output
-  functions, but the complete conversion specification is not exactly %% (7.21.6.1,
-  7.21.6.2, 7.28.2.1, 7.28.2.2).
--- An invalid conversion specification is found in the format for one of the formatted
-  input/output functions, or the strftime or wcsftime function (7.21.6.1, 7.21.6.2,
-
-[page 562] (Contents)
-
-   7.26.3.5, 7.28.2.1, 7.28.2.2, 7.28.5.1).
--- The number of characters transmitted by a formatted output function is greater than
-  INT_MAX (7.21.6.1, 7.21.6.3, 7.21.6.8, 7.21.6.10).
--- The result of a conversion by one of the formatted input functions cannot be
-  represented in the corresponding object, or the receiving object does not have an
-  appropriate type (7.21.6.2, 7.28.2.2).
--- A c, s, or [ conversion specifier is encountered by one of the formatted input
-  functions, and the array pointed to by the corresponding argument is not large enough
-  to accept the input sequence (and a null terminator if the conversion specifier is s or
-  [) (7.21.6.2, 7.28.2.2).
--- A c, s, or [ conversion specifier with an l qualifier is encountered by one of the
-  formatted input functions, but the input is not a valid multibyte character sequence
-  that begins in the initial shift state (7.21.6.2, 7.28.2.2).
--- The input item for a %p conversion by one of the formatted input functions is not a
-  value converted earlier during the same program execution (7.21.6.2, 7.28.2.2).
--- The vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf,
-  vsscanf, vfwprintf, vfwscanf, vswprintf, vswscanf, vwprintf, or
-  vwscanf function is called with an improperly initialized va_list argument, or
-  the argument is used (other than in an invocation of va_end) after the function
-  returns (7.21.6.8, 7.21.6.9, 7.21.6.10, 7.21.6.11, 7.21.6.12, 7.21.6.13, 7.21.6.14,
-  7.28.2.5, 7.28.2.6, 7.28.2.7, 7.28.2.8, 7.28.2.9, 7.28.2.10).
--- The contents of the array supplied in a call to the fgets or fgetws function are
-  used after a read error occurred (7.21.7.2, 7.28.3.2).
--- The file position indicator for a binary stream is used after a call to the ungetc
-  function where its value was zero before the call (7.21.7.10).
--- The file position indicator for a stream is used after an error occurred during a call to
-  the fread or fwrite function (7.21.8.1, 7.21.8.2).
--- A partial element read by a call to the fread function is used (7.21.8.1).
--- The fseek function is called for a text stream with a nonzero offset and either the
-  offset was not returned by a previous successful call to the ftell function on a
-  stream associated with the same file or whence is not SEEK_SET (7.21.9.2).
--- The fsetpos function is called to set a position that was not returned by a previous
-  successful call to the fgetpos function on a stream associated with the same file
-  (7.21.9.3).
--- A non-null pointer returned by a call to the calloc, malloc, or realloc function
-  with a zero requested size is used to access an object (7.22.3).
-
-[page 563] (Contents)
-
--- The value of a pointer that refers to space deallocated by a call to the free or
-  realloc function is used (7.22.3).
--- The alignment requested of the aligned_alloc function is not valid or not
-  supported by the implementation, or the size requested is not an integral multiple of
-  the alignment (7.22.3.1).
--- The pointer argument to the free or realloc function does not match a pointer
-  earlier returned by a memory management function, or the space has been deallocated
-  by a call to free or realloc (7.22.3.3, 7.22.3.5).
--- The value of the object allocated by the malloc function is used (7.22.3.4).
--- The value of any bytes in a new object allocated by the realloc function beyond
-  the size of the old object are used (7.22.3.5).
--- The program calls the exit or quick_exit function more than once, or calls both
-  functions (7.22.4.4, 7.22.4.7).
--- During the call to a function registered with the atexit or at_quick_exit
-  function, a call is made to the longjmp function that would terminate the call to the
-  registered function (7.22.4.4, 7.22.4.7).
--- The string set up by the getenv or strerror function is modified by the program
-  (7.22.4.6, 7.23.6.2).
--- A command is executed through the system function in a way that is documented as
-  causing termination or some other form of undefined behavior (7.22.4.8).
--- A searching or sorting utility function is called with an invalid pointer argument, even
-  if the number of elements is zero (7.22.5).
--- The comparison function called by a searching or sorting utility function alters the
-  contents of the array being searched or sorted, or returns ordering values
-  inconsistently (7.22.5).
--- The array being searched by the bsearch function does not have its elements in
-  proper order (7.22.5.1).
--- The current conversion state is used by a multibyte/wide character conversion
-  function after changing the LC_CTYPE category (7.22.7).
--- A string or wide string utility function is instructed to access an array beyond the end
-  of an object (7.23.1, 7.28.4).
--- A string or wide string utility function is called with an invalid pointer argument, even
-  if the length is zero (7.23.1, 7.28.4).
--- The contents of the destination array are used after a call to the strxfrm,
-  strftime, wcsxfrm, or wcsftime function in which the specified length was
-
-[page 564] (Contents)
-
-   too small to hold the entire null-terminated result (7.23.4.5, 7.26.3.5, 7.28.4.4.4,
-   7.28.5.1).
--- The first argument in the very first call to the strtok or wcstok is a null pointer
-  (7.23.5.8, 7.28.4.5.7).
--- The type of an argument to a type-generic macro is not compatible with the type of
-  the corresponding parameter of the selected function (7.24).
--- A complex argument is supplied for a generic parameter of a type-generic macro that
-  has no corresponding complex function (7.24).
--- At least one field of the broken-down time passed to asctime contains a value
-  outside its normal range, or the calculated year exceeds four digits or is less than the
-  year 1000 (7.26.3.1).
--- The argument corresponding to an s specifier without an l qualifier in a call to the
-  fwprintf function does not point to a valid multibyte character sequence that
-  begins in the initial shift state (7.28.2.11).
--- In a call to the wcstok function, the object pointed to by ptr does not have the
-  value stored by the previous call for the same wide string (7.28.4.5.7).
--- An mbstate_t object is used inappropriately (7.28.6).
--- The value of an argument of type wint_t to a wide character classification or case
-  mapping function is neither equal to the value of WEOF nor representable as a
-  wchar_t (7.29.1).
--- The iswctype function is called using a different LC_CTYPE category from the
-  one in effect for the call to the wctype function that returned the description
-  (7.29.2.2.1).
--- The towctrans function is called using a different LC_CTYPE category from the
-  one in effect for the call to the wctrans function that returned the description
-  (7.29.3.2.1).
-
-
-
-
-[page 565] (Contents)
-
-    J.3 Implementation-defined behavior
-1   A conforming implementation is required to document its choice of behavior in each of
-    the areas listed in this subclause. The following are implementation-defined:
-    J.3.1 Translation
-1   -- How a diagnostic is identified (3.10, 5.1.1.3).
-    -- Whether each nonempty sequence of white-space characters other than new-line is
-      retained or replaced by one space character in translation phase 3 (5.1.1.2).
-    J.3.2 Environment
-1   -- The mapping between physical source file multibyte characters and the source
-      character set in translation phase 1 (5.1.1.2).
-    -- The name and type of the function called at program startup in a freestanding
-      environment (5.1.2.1).
-    -- The effect of program termination in a freestanding environment (5.1.2.1).
-    -- An alternative manner in which the main function may be defined (5.1.2.2.1).
-    -- The values given to the strings pointed to by the argv argument to main (5.1.2.2.1).
-    -- What constitutes an interactive device (5.1.2.3).
-    -- Whether a program can have more than one thread of execution in a freestanding
-      environment (5.1.2.4).
-    -- The set of signals, their semantics, and their default handling (7.14).
-    -- Signal values other than SIGFPE, SIGILL, and SIGSEGV that correspond to a
-      computational exception (7.14.1.1).
-    -- Signals for which the equivalent of signal(sig, SIG_IGN); is executed at
-      program startup (7.14.1.1).
-    -- The set of environment names and the method for altering the environment list used
-      by the getenv function (7.22.4.6).
-    -- The manner of execution of the string by the system function (7.22.4.8).
-
-
-
-
-[page 566] (Contents)
-
-    J.3.3 Identifiers
-1   -- Which additional multibyte characters may appear in identifiers and their
-      correspondence to universal character names (6.4.2).
-    -- The number of significant initial characters in an identifier (5.2.4.1, 6.4.2).
-    J.3.4 Characters
-1   -- The number of bits in a byte (3.6).
-    -- The values of the members of the execution character set (5.2.1).
-    -- The unique value of the member of the execution character set produced for each of
-      the standard alphabetic escape sequences (5.2.2).
-    -- The value of a char object into which has been stored any character other than a
-      member of the basic execution character set (6.2.5).
-    -- Which of signed char or unsigned char has the same range, representation,
-      and behavior as ''plain'' char (6.2.5, 6.3.1.1).
-    -- The mapping of members of the source character set (in character constants and string
-      literals) to members of the execution character set (6.4.4.4, 5.1.1.2).
-    -- The value of an integer character constant containing more than one character or
-      containing a character or escape sequence that does not map to a single-byte
-      execution character (6.4.4.4).
-    -- The value of a wide character constant containing more than one multibyte character
-      or a single multibyte character that maps to multiple members of the extended
-      execution character set, or containing a multibyte character or escape sequence not
-      represented in the extended execution character set (6.4.4.4).
-    -- The current locale used to convert a wide character constant consisting of a single
-      multibyte character that maps to a member of the extended execution character set
-      into a corresponding wide character code (6.4.4.4).
-    -- Whether differently-prefixed wide string literal tokens can be concatenated and, if so,
-      the treatment of the resulting multibyte character sequence (6.4.5).
-    -- The current locale used to convert a wide string literal into corresponding wide
-      character codes (6.4.5).
-    -- The value of a string literal containing a multibyte character or escape sequence not
-      represented in the execution character set (6.4.5).
-    -- The encoding of any of wchar_t, char16_t, and char32_t where the
-      corresponding  standard   encoding macro      (__STDC_ISO_10646__,
-      __STDC_UTF_16__, or __STDC_UTF_32__) is not defined (6.10.8.2).
-
-[page 567] (Contents)
-
-    J.3.5 Integers
-1   -- Any extended integer types that exist in the implementation (6.2.5).
-    -- Whether signed integer types are represented using sign and magnitude, two's
-      complement, or ones' complement, and whether the extraordinary value is a trap
-      representation or an ordinary value (6.2.6.2).
-    -- The rank of any extended integer type relative to another extended integer type with
-      the same precision (6.3.1.1).
-    -- The result of, or the signal raised by, converting an integer to a signed integer type
-      when the value cannot be represented in an object of that type (6.3.1.3).
-    -- The results of some bitwise operations on signed integers (6.5).
-    J.3.6 Floating point
-1   -- The accuracy of the floating-point operations and of the library functions in
-      <math.h> and <complex.h> that return floating-point results (5.2.4.2.2).
-    -- The accuracy of the conversions between floating-point internal representations and
-      string representations performed by the library functions in <stdio.h>,
-      <stdlib.h>, and <wchar.h> (5.2.4.2.2).
-    -- The rounding behaviors characterized by non-standard values of FLT_ROUNDS
-      (5.2.4.2.2).
-    -- The evaluation methods characterized by non-standard negative values of
-      FLT_EVAL_METHOD (5.2.4.2.2).
-    -- The direction of rounding when an integer is converted to a floating-point number that
-      cannot exactly represent the original value (6.3.1.4).
-    -- The direction of rounding when a floating-point number is converted to a narrower
-      floating-point number (6.3.1.5).
-    -- How the nearest representable value or the larger or smaller representable value
-      immediately adjacent to the nearest representable value is chosen for certain floating
-      constants (6.4.4.2).
-    -- Whether and how floating expressions are contracted when not disallowed by the
-      FP_CONTRACT pragma (6.5).
-    -- The default state for the FENV_ACCESS pragma (7.6.1).
-    -- Additional floating-point exceptions, rounding           modes,     environments,     and
-      classifications, and their macro names (7.6, 7.12).
-    -- The default state for the FP_CONTRACT pragma (7.12.2).
-
-
-[page 568] (Contents)
-
-    J.3.7 Arrays and pointers
-1   -- The result of converting a pointer to an integer or vice versa (6.3.2.3).
-    -- The size of the result of subtracting two pointers to elements of the same array
-      (6.5.6).
-    J.3.8 Hints
-1   -- The extent to which suggestions made by using the register storage-class
-      specifier are effective (6.7.1).
-    -- The extent to which suggestions made by using the inline function specifier are
-      effective (6.7.4).
-    J.3.9 Structures, unions, enumerations, and bit-fields
-1   -- Whether a ''plain'' int bit-field is treated as a signed int bit-field or as an
-      unsigned int bit-field (6.7.2, 6.7.2.1).
-    -- Allowable bit-field types other than _Bool, signed int, and unsigned int
-      (6.7.2.1).
-    -- Whether a bit-field can straddle a storage-unit boundary (6.7.2.1).
-    -- The order of allocation of bit-fields within a unit (6.7.2.1).
-    -- The alignment of non-bit-field members of structures (6.7.2.1). This should present
-      no problem unless binary data written by one implementation is read by another.
-    -- The integer type compatible with each enumerated type (6.7.2.2).
-    J.3.10 Qualifiers
-1   -- What constitutes an access to an object that has volatile-qualified type (6.7.3).
-    J.3.11 Preprocessing directives
-1   -- The locations within #pragma directives where header name preprocessing tokens
-      are recognized (6.4, 6.4.7).
-    -- How sequences in both forms of header names are mapped to headers or external
-      source file names (6.4.7).
-    -- Whether the value of a character constant in a constant expression that controls
-      conditional inclusion matches the value of the same character constant in the
-      execution character set (6.10.1).
-    -- Whether the value of a single-character character constant in a constant expression
-      that controls conditional inclusion may have a negative value (6.10.1).
-    -- The places that are searched for an included < > delimited header, and how the places
-      are specified or the header is identified (6.10.2).
-[page 569] (Contents)
-
-    -- How the named source file is searched for in an included " " delimited header
-      (6.10.2).
-    -- The method by which preprocessing tokens (possibly resulting from macro
-      expansion) in a #include directive are combined into a header name (6.10.2).
-    -- The nesting limit for #include processing (6.10.2).
-    -- Whether the # operator inserts a \ character before the \ character that begins a
-      universal character name in a character constant or string literal (6.10.3.2).
-    -- The behavior on each recognized non-STDC #pragma directive (6.10.6).
-    -- The definitions for __DATE__ and __TIME__ when respectively, the date and
-      time of translation are not available (6.10.8.1).
-    J.3.12 Library functions
-1   -- Any library facilities available to a freestanding program, other than the minimal set
-      required by clause 4 (5.1.2.1).
-    -- The format of the diagnostic printed by the assert macro (7.2.1.1).
-    -- The representation of the floating-point               status   flags   stored   by   the
-      fegetexceptflag function (7.6.2.2).
-    -- Whether the feraiseexcept function raises the ''inexact'' floating-point
-      exception in addition to the ''overflow'' or ''underflow'' floating-point exception
-      (7.6.2.3).
-    -- Strings other than "C" and "" that may be passed as the second argument to the
-      setlocale function (7.11.1.1).
-    -- The types defined for float_t and double_t when the value of the
-      FLT_EVAL_METHOD macro is less than 0 (7.12).
-    -- Domain errors for the mathematics functions, other than those required by this
-      International Standard (7.12.1).
-    -- The values returned by the mathematics functions on domain errors or pole errors
-      (7.12.1).
-    -- The values returned by the mathematics functions on underflow range errors, whether
-      errno is set to the value of the macro ERANGE when the integer expression
-      math_errhandling & MATH_ERRNO is nonzero, and whether the ''underflow''
-      floating-point exception is raised when the integer expression math_errhandling
-      & MATH_ERREXCEPT is nonzero. (7.12.1).
-    -- Whether a domain error occurs or zero is returned when an fmod function has a
-      second argument of zero (7.12.10.1).
-
-[page 570] (Contents)
-
--- Whether a domain error occurs or zero is returned when a remainder function has
-  a second argument of zero (7.12.10.2).
--- The base-2 logarithm of the modulus used by the remquo functions in reducing the
-  quotient (7.12.10.3).
--- Whether a domain error occurs or zero is returned when a remquo function has a
-  second argument of zero (7.12.10.3).
--- Whether the equivalent of signal(sig, SIG_DFL); is executed prior to the call
-  of a signal handler, and, if not, the blocking of signals that is performed (7.14.1.1).
--- The null pointer constant to which the macro NULL expands (7.19).
--- Whether the last line of a text stream requires a terminating new-line character
-  (7.21.2).
--- Whether space characters that are written out to a text stream immediately before a
-  new-line character appear when read in (7.21.2).
--- The number of null characters that may be appended to data written to a binary
-  stream (7.21.2).
--- Whether the file position indicator of an append-mode stream is initially positioned at
-  the beginning or end of the file (7.21.3).
--- Whether a write on a text stream causes the associated file to be truncated beyond that
-  point (7.21.3).
--- The characteristics of file buffering (7.21.3).
--- Whether a zero-length file actually exists (7.21.3).
--- The rules for composing valid file names (7.21.3).
--- Whether the same file can be simultaneously open multiple times (7.21.3).
--- The nature and choice of encodings used for multibyte characters in files (7.21.3).
--- The effect of the remove function on an open file (7.21.4.1).
--- The effect if a file with the new name exists prior to a call to the rename function
-  (7.21.4.2).
--- Whether an open temporary file is removed upon abnormal program termination
-  (7.21.4.3).
--- Which changes of mode are permitted (if any), and under what circumstances
-  (7.21.5.4).
--- The style used to print an infinity or NaN, and the meaning of any n-char or n-wchar
-  sequence printed for a NaN (7.21.6.1, 7.28.2.1).
-
-[page 571] (Contents)
-
--- The output for %p conversion in the fprintf or fwprintf function (7.21.6.1,
-  7.28.2.1).
--- The interpretation of a - character that is neither the first nor the last character, nor
-  the second where a ^ character is the first, in the scanlist for %[ conversion in the
-  fscanf or fwscanf function (7.21.6.2, 7.28.2.1).
--- The set of sequences matched by a %p conversion and the interpretation of the
-  corresponding input item in the fscanf or fwscanf function (7.21.6.2, 7.28.2.2).
--- The value to which the macro errno is set by the fgetpos, fsetpos, or ftell
-  functions on failure (7.21.9.1, 7.21.9.3, 7.21.9.4).
--- The meaning of any n-char or n-wchar sequence in a string representing a NaN that is
-  converted by the strtod, strtof, strtold, wcstod, wcstof, or wcstold
-  function (7.22.1.3, 7.28.4.1.1).
--- Whether or not the strtod, strtof, strtold, wcstod, wcstof, or wcstold
-  function sets errno to ERANGE when underflow occurs (7.22.1.3, 7.28.4.1.1).
--- Whether the calloc, malloc, and realloc functions return a null pointer or a
-  pointer to an allocated object when the size requested is zero (7.22.3).
--- Whether open streams with unwritten buffered data are flushed, open streams are
-  closed, or temporary files are removed when the abort or _Exit function is called
-  (7.22.4.1, 7.22.4.5).
--- The termination status returned to the host environment by the abort, exit,
-  _Exit, or quick_exit function (7.22.4.1, 7.22.4.4, 7.22.4.5, 7.22.4.7).
--- The value returned by the system function when its argument is not a null pointer
-  (7.22.4.8).
--- The local time zone and Daylight Saving Time (7.26.1).
--- The range and precision of times representable in clock_t and time_t (7.26).
--- The era for the clock function (7.26.2.1).
--- The replacement string for the %Z specifier to the strftime, and wcsftime
-  functions in the "C" locale (7.26.3.5, 7.28.5.1).
--- Whether the functions in <math.h> honor the rounding direction mode in an
-  IEC 60559 conformant implementation, unless explicitly specified otherwise (F.10).
-
-
-
-
-[page 572] (Contents)
-
-    J.3.13 Architecture
-1   -- The values or expressions assigned to the macros specified in the headers
-      <float.h>, <limits.h>, and <stdint.h> (5.2.4.2, 7.20.2, 7.20.3).
-    -- The result of attempting to indirectly access an object with automatic or thread
-      storage duration from a thread other than the one with which it is associated (6.2.4).
-    -- The number, order, and encoding of bytes in any object (when not explicitly specified
-      in this International Standard) (6.2.6.1).
-    -- Whether any extended alignments are supported and the contexts in which they are
-      supported (6.2.8).
-    -- Valid alignment values other than those returned by an alignof expression for
-      fundamental types, if any (6.2.8).
-    -- The value of the result of the sizeof and alignof operators (6.5.3.4).
-    J.4 Locale-specific behavior
-1   The following characteristics of a hosted environment are locale-specific and are required
-    to be documented by the implementation:
-    -- Additional members of the source and execution character sets beyond the basic
-      character set (5.2.1).
-    -- The presence, meaning, and representation of additional multibyte characters in the
-      execution character set beyond the basic character set (5.2.1.2).
-    -- The shift states used for the encoding of multibyte characters (5.2.1.2).
-    -- The direction of writing of successive printing characters (5.2.2).
-    -- The decimal-point character (7.1.1).
-    -- The set of printing characters (7.4, 7.29.2).
-    -- The set of control characters (7.4, 7.29.2).
-    -- The sets of characters tested for by the isalpha, isblank, islower, ispunct,
-      isspace, isupper, iswalpha, iswblank, iswlower, iswpunct,
-      iswspace, or iswupper functions (7.4.1.2, 7.4.1.3, 7.4.1.7, 7.4.1.9, 7.4.1.10,
-      7.4.1.11, 7.29.2.1.2, 7.29.2.1.3, 7.29.2.1.7, 7.29.2.1.9, 7.29.2.1.10, 7.29.2.1.11).
-    -- The native environment (7.11.1.1).
-    -- Additional subject sequences accepted by the numeric conversion functions (7.22.1,
-      7.28.4.1).
-    -- The collation sequence of the execution character set (7.23.4.3, 7.28.4.4.2).
-
-
-[page 573] (Contents)
-
-    -- The contents of the error message strings set up by the strerror function
-      (7.23.6.2).
-    -- The formats for time and date (7.26.3.5, 7.28.5.1).
-    -- Character mappings that are supported by the towctrans function (7.29.1).
-    -- Character classifications that are supported by the iswctype function (7.29.1).
-    J.5 Common extensions
-1   The following extensions are widely used in many systems, but are not portable to all
-    implementations. The inclusion of any extension that may cause a strictly conforming
-    program to become invalid renders an implementation nonconforming. Examples of such
-    extensions are new keywords, extra library functions declared in standard headers, or
-    predefined macros with names that do not begin with an underscore.
-    J.5.1 Environment arguments
-1   In a hosted environment, the main function receives a third argument, char *envp[],
-    that points to a null-terminated array of pointers to char, each of which points to a string
-    that provides information about the environment for this execution of the program
-    (5.1.2.2.1).
-    J.5.2 Specialized identifiers
-1   Characters other than the underscore _, letters, and digits, that are not part of the basic
-    source character set (such as the dollar sign $, or characters in national character sets)
-    may appear in an identifier (6.4.2).
-    J.5.3 Lengths and cases of identifiers
-1   All characters in identifiers (with or without external linkage) are significant (6.4.2).
-    J.5.4 Scopes of identifiers
-1   A function identifier, or the identifier of an object the declaration of which contains the
-    keyword extern, has file scope (6.2.1).
-    J.5.5 Writable string literals
-1   String literals are modifiable (in which case, identical string literals should denote distinct
-    objects) (6.4.5).
-
-
-
-
-[page 574] (Contents)
-
-    J.5.6 Other arithmetic types
-1   Additional arithmetic types, such as __int128 or double double, and their
-    appropriate conversions are defined (6.2.5, 6.3.1). Additional floating types may have
-    more range or precision than long double, may be used for evaluating expressions of
-    other floating types, and may be used to define float_t or double_t.
-    J.5.7 Function pointer casts
-1   A pointer to an object or to void may be cast to a pointer to a function, allowing data to
-    be invoked as a function (6.5.4).
-2   A pointer to a function may be cast to a pointer to an object or to void, allowing a
-    function to be inspected or modified (for example, by a debugger) (6.5.4).
-    J.5.8 Extended bit-field types
-1   A bit-field may be declared with a type other than _Bool, unsigned int, or
-    signed int, with an appropriate maximum width (6.7.2.1).
-    J.5.9 The fortran keyword
-1   The fortran function specifier may be used in a function declaration to indicate that
-    calls suitable for FORTRAN should be generated, or that a different representation for the
-    external name is to be generated (6.7.4).
-    J.5.10 The asm keyword
-1   The asm keyword may be used to insert assembly language directly into the translator
-    output (6.8). The most common implementation is via a statement of the form:
-              asm ( character-string-literal );
-    J.5.11 Multiple external definitions
-1   There may be more than one external definition for the identifier of an object, with or
-    without the explicit use of the keyword extern; if the definitions disagree, or more than
-    one is initialized, the behavior is undefined (6.9.2).
-    J.5.12 Predefined macro names
-1   Macro names that do not begin with an underscore, describing the translation and
-    execution environments, are defined by the implementation before translation begins
-    (6.10.8).
-
-
-
-
-[page 575] (Contents)
-
-    J.5.13 Floating-point status flags
-1   If any floating-point status flags are set on normal termination after all calls to functions
-    registered by the atexit function have been made (see 7.22.4.4), the implementation
-    writes some diagnostics indicating the fact to the stderr stream, if it is still open,
-    J.5.14 Extra arguments for signal handlers
-1   Handlers for specific signals are called with extra arguments in addition to the signal
-    number (7.14.1.1).
-    J.5.15 Additional stream types and file-opening modes
-1   Additional mappings from files to streams are supported (7.21.2).
-2   Additional file-opening modes may be specified by characters appended to the mode
-    argument of the fopen function (7.21.5.3).
-    J.5.16 Defined file position indicator
-1   The file position indicator is decremented by each successful call to the ungetc or
-    ungetwc function for a text stream, except if its value was zero before a call (7.21.7.10,
-    7.28.3.10).
-    J.5.17 Math error reporting
-1   Functions declared in <complex.h> and <math.h> raise SIGFPE to report errors
-    instead of, or in addition to, setting errno or raising floating-point exceptions (7.3,
-    7.12).
-
-
-
-
-[page 576] (Contents)
-
-                                           Annex K
-                                          (normative)
-                              Bounds-checking interfaces
-    K.1 Background
-1   Traditionally, the C Library has contained many functions that trust the programmer to
-    provide output character arrays big enough to hold the result being produced. Not only
-    do these functions not check that the arrays are big enough, they frequently lack the
-    information needed to perform such checks. While it is possible to write safe, robust, and
-    error-free code using the existing library, the library tends to promote programming styles
-    that lead to mysterious failures if a result is too big for the provided array.
-2   A common programming style is to declare character arrays large enough to handle most
-    practical cases. However, if these arrays are not large enough to handle the resulting
-    strings, data can be written past the end of the array overwriting other data and program
-    structures. The program never gets any indication that a problem exists, and so never has
-    a chance to recover or to fail gracefully.
-3   Worse, this style of programming has compromised the security of computers and
-    networks. Buffer overflows can often be exploited to run arbitrary code with the
-    permissions of the vulnerable (defective) program.
-4   If the programmer writes runtime checks to verify lengths before calling library
-    functions, then those runtime checks frequently duplicate work done inside the library
-    functions, which discover string lengths as a side effect of doing their job.
-5   This annex provides alternative library functions that promote safer, more secure
-    programming. The alternative functions verify that output buffers are large enough for
-    the intended result and return a failure indicator if they are not. Data is never written past
-    the end of an array. All string results are null terminated.
-6   This annex also addresses another problem that complicates writing robust code:
-    functions that are not reentrant because they return pointers to static objects owned by the
-    function. Such functions can be troublesome since a previously returned result can
-    change if the function is called again, perhaps by another thread.
-
-
-
-
-[page 577] (Contents)
-
-    K.2 Scope
-1   This annex specifies a series of optional extensions that can be useful in the mitigation of
-    security vulnerabilities in programs, and comprise new functions, macros, and types
-    declared or defined in existing standard headers.
-2   An implementation that defines __STDC_LIB_EXT1__ shall conform to the
-    specifications in this annex.361)
-3   Subclause K.3 should be read as if it were merged into the parallel structure of named
-    subclauses of clause 7.
-    K.3 Library
-    K.3.1 Introduction
-    K.3.1.1 Standard headers
-1   The functions, macros, and types declared or defined in K.3 and its subclauses are not
-    declared or defined by their respective headers if __STDC_WANT_LIB_EXT1__ is
-    defined as a macro which expands to the integer constant 0 at the point in the source file
-    where the appropriate header is first included.
-2   The functions, macros, and types declared or defined in K.3 and its subclauses are
-    declared and defined by their respective headers if __STDC_WANT_LIB_EXT1__ is
-    defined as a macro which expands to the integer constant 1 at the point in the source file
-    where the appropriate header is first included.362)
-3   It is implementation-defined whether the functions, macros, and types declared or defined
-    in K.3 and its subclauses are declared or defined by their respective headers if
-    __STDC_WANT_LIB_EXT1__ is not defined as a macro at the point in the source file
-    where the appropriate header is first included.363)
-4   Within a preprocessing translation unit, __STDC_WANT_LIB_EXT1__ shall be
-    defined identically for all inclusions of any headers from subclause K.3. If
-    __STDC_WANT_LIB_EXT1__ is defined differently for any such inclusion, the
-    implementation shall issue a diagnostic as if a preprocessor error directive were used.
-
-
-    361) Implementations that do not define __STDC_LIB_EXT1__ are not required to conform to these
-         specifications.
-    362) Future revisions of this International Standard may define meanings for other values of
-         __STDC_WANT_LIB_EXT1__.
-    363) Subclause 7.1.3 reserves certain names and patterns of names that an implementation may use in
-         headers. All other names are not reserved, and a conforming implementation is not permitted to use
-         them. While some of the names defined in K.3 and its subclauses are reserved, others are not. If an
-         unreserved name is defined in a header when __STDC_WANT_LIB_EXT1__ is defined as 0, the
-         implementation is not conforming.
-
-[page 578] (Contents)
-
-    K.3.1.2 Reserved identifiers
-1   Each macro name in any of the following subclauses is reserved for use as specified if it
-    is defined by any of its associated headers when included; unless explicitly stated
-    otherwise (see 7.1.4).
-2   All identifiers with external linkage in any of the following subclauses are reserved for
-    use as identifiers with external linkage if any of them are used by the program. None of
-    them are reserved if none of them are used.
-3   Each identifier with file scope listed in any of the following subclauses is reserved for use
-    as a macro name and as an identifier with file scope in the same name space if it is
-    defined by any of its associated headers when included.
-    K.3.1.3 Use of errno
-1   An implementation may set errno for the functions defined in this annex, but is not
-    required to.
-    K.3.1.4 Runtime-constraint violations
-1   Most functions in this annex include as part of their specification a list of runtime-
-    constraints. These runtime-constraints are requirements on the program using the
-    library.364)
-2   Implementations shall verify that the runtime-constraints for a function are not violated
-    by the program. If a runtime-constraint is violated, the implementation shall call the
-    currently registered runtime-constraint handler (see set_constraint_handler_s
-    in <stdlib.h>). Multiple runtime-constraint violations in the same call to a library
-    function result in only one call to the runtime-constraint handler. It is unspecified which
-    one of the multiple runtime-constraint violations cause the handler to be called.
-3   If the runtime-constraints section for a function states an action to be performed when a
-    runtime-constraint violation occurs, the function shall perform the action before calling
-    the runtime-constraint handler. If the runtime-constraints section lists actions that are
-    prohibited when a runtime-constraint violation occurs, then such actions are prohibited to
-    the function both before calling the handler and after the handler returns.
-4   The runtime-constraint handler might not return. If the handler does return, the library
-    function whose runtime-constraint was violated shall return some indication of failure as
-    given by the returns section in the function's specification.
-
-
-
-    364) Although runtime-constraints replace many cases of undefined behavior, undefined behavior still
-         exists in this annex. Implementations are free to detect any case of undefined behavior and treat it as a
-         runtime-constraint violation by calling the runtime-constraint handler. This license comes directly
-         from the definition of undefined behavior.
-
-[page 579] (Contents)
-
-    K.3.2 Errors <errno.h>
-1   The header <errno.h> defines a type.
-2   The type is
-            errno_t
-    which is type int.365)
-    K.3.3 Common definitions <stddef.h>
-1   The header <stddef.h> defines a type.
-2   The type is
-            rsize_t
-    which is the type size_t.366)
-    K.3.4 Integer types <stdint.h>
-1   The header <stdint.h> defines a macro.
-2   The macro is
-            RSIZE_MAX
-    which expands to a value367) of type size_t. Functions that have parameters of type
-    rsize_t consider it a runtime-constraint violation if the values of those parameters are
-    greater than RSIZE_MAX.
-    Recommended practice
-3   Extremely large object sizes are frequently a sign that an object's size was calculated
-    incorrectly. For example, negative numbers appear as very large positive numbers when
-    converted to an unsigned type like size_t. Also, some implementations do not support
-    objects as large as the maximum value that can be represented by type size_t.
-4   For those reasons, it is sometimes beneficial to restrict the range of object sizes to detect
-    programming errors. For implementations targeting machines with large address spaces,
-    it is recommended that RSIZE_MAX be defined as the smaller of the size of the largest
-    object supported or (SIZE_MAX >> 1), even if this limit is smaller than the size of
-    some legitimate, but very large, objects. Implementations targeting machines with small
-    address spaces may wish to define RSIZE_MAX as SIZE_MAX, which means that there
-
-    365) As a matter of programming style, errno_t may be used as the type of something that deals only
-         with the values that might be found in errno. For example, a function which returns the value of
-         errno might be declared as having the return type errno_t.
-    366) See the description of the RSIZE_MAX macro in <stdint.h>.
-    367) The macro RSIZE_MAX need not expand to a constant expression.
-
-[page 580] (Contents)
-
-    is no object size that is considered a runtime-constraint violation.
-    K.3.5 Input/output <stdio.h>
-1   The header <stdio.h> defines several macros and two types.
-2   The macros are
-            L_tmpnam_s
-    which expands to an integer constant expression that is the size needed for an array of
-    char large enough to hold a temporary file name string generated by the tmpnam_s
-    function;
-            TMP_MAX_S
-    which expands to an integer constant expression that is the maximum number of unique
-    file names that can be generated by the tmpnam_s function.
-3   The types are
-            errno_t
-    which is type int; and
-            rsize_t
-    which is the type size_t.
-    K.3.5.1 Operations on files
-    K.3.5.1.1 The tmpfile_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            errno_t tmpfile_s(FILE * restrict * restrict streamptr);
-    Runtime-constraints
-2   streamptr shall not be a null pointer.
-3   If there is a runtime-constraint violation, tmpfile_s does not attempt to create a file.
-    Description
-4   The tmpfile_s function creates a temporary binary file that is different from any other
-    existing file and that will automatically be removed when it is closed or at program
-    termination. If the program terminates abnormally, whether an open temporary file is
-    removed is implementation-defined. The file is opened for update with "wb+" mode
-    with the meaning that mode has in the fopen_s function (including the mode's effect
-    on exclusive access and file permissions).
-
-
-[page 581] (Contents)
-
-5   If the file was created successfully, then the pointer to FILE pointed to by streamptr
-    will be set to the pointer to the object controlling the opened file. Otherwise, the pointer
-    to FILE pointed to by streamptr will be set to a null pointer.
-    Recommended practice
-    It should be possible to open at least TMP_MAX_S temporary files during the lifetime of
-    the program (this limit may be shared with tmpnam_s) and there should be no limit on
-    the number simultaneously open other than this limit and any limit on the number of open
-    files (FOPEN_MAX).
-    Returns
-6   The tmpfile_s function returns zero if it created the file. If it did not create the file or
-    there was a runtime-constraint violation, tmpfile_s returns a nonzero value.
-    K.3.5.1.2 The tmpnam_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            errno_t tmpnam_s(char *s, rsize_t maxsize);
-    Runtime-constraints
-2   s shall not be a null pointer. maxsize shall be less than or equal to RSIZE_MAX.
-    maxsize shall be greater than the length of the generated file name string.
-    Description
-3   The tmpnam_s function generates a string that is a valid file name and that is not the
-    same as the name of an existing file.368) The function is potentially capable of generating
-    TMP_MAX_S different strings, but any or all of them may already be in use by existing
-    files and thus not be suitable return values. The lengths of these strings shall be less than
-    the value of the L_tmpnam_s macro.
-4   The tmpnam_s function generates a different string each time it is called.
-5   It is assumed that s points to an array of at least maxsize characters. This array will be
-    set to generated string, as specified below.
-
-
-
-    368) Files created using strings generated by the tmpnam_s function are temporary only in the sense that
-         their names should not collide with those generated by conventional naming rules for the
-         implementation. It is still necessary to use the remove function to remove such files when their use
-         is ended, and before program termination. Implementations should take care in choosing the patterns
-         used for names returned by tmpnam_s. For example, making a thread id part of the names avoids the
-         race condition and possible conflict when multiple programs run simultaneously by the same user
-         generate the same temporary file names.
-
-[page 582] (Contents)
-
-6    The implementation shall behave as if no library function except tmpnam calls the
-     tmpnam_s function.369)
-     Recommended practice
-7    After a program obtains a file name using the tmpnam_s function and before the
-     program creates a file with that name, the possibility exists that someone else may create
-     a file with that same name. To avoid this race condition, the tmpfile_s function
-     should be used instead of tmpnam_s when possible. One situation that requires the use
-     of the tmpnam_s function is when the program needs to create a temporary directory
-     rather than a temporary file.
-     Returns
-8    If no suitable string can be generated, or if there is a runtime-constraint violation, the
-     tmpnam_s function writes a null character to s[0] (only if s is not null and maxsize
-     is greater than zero) and returns a nonzero value.
-9    Otherwise, the tmpnam_s function writes the string in the array pointed to by s and
-     returns zero.
-     Environmental limits
-10   The value of the macro TMP_MAX_S shall be at least 25.
-     K.3.5.2 File access functions
-     K.3.5.2.1 The fopen_s function
-     Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdio.h>
-             errno_t fopen_s(FILE * restrict * restrict streamptr,
-                  const char * restrict filename,
-                  const char * restrict mode);
-     Runtime-constraints
-2    None of streamptr, filename, or mode shall be a null pointer.
-3    If there is a runtime-constraint violation, fopen_s does not attempt to open a file.
-     Furthermore, if streamptr is not a null pointer, fopen_s sets *streamptr to the
-     null pointer.
-
-
-
-
-     369) An implementation may have tmpnam call tmpnam_s (perhaps so there is only one naming
-          convention for temporary files), but this is not required.
-
-[page 583] (Contents)
-
-    Description
-4   The fopen_s function opens the file whose name is the string pointed to by
-    filename, and associates a stream with it.
-5   The mode string shall be as described for fopen, with the addition that modes starting
-    with the character 'w' or 'a' may be preceded by the character 'u', see below:
-    uw             truncate to zero length or create text file for writing, default
-                   permissions
-    uwx            create text file for writing, default permissions
-    ua             append; open or create text file for writing at end-of-file, default
-                   permissions
-    uwb            truncate to zero length or create binary file for writing, default
-                   permissions
-    uwbx           create binary file for writing, default permissions
-    uab            append; open or create binary file for writing at end-of-file, default
-                   permissions
-    uw+            truncate to zero length or create text file for update, default
-                   permissions
-    uw+x           create text file for update, default permissions
-    ua+            append; open or create text file for update, writing at end-of-file,
-                   default permissions
-    uw+b or uwb+   truncate to zero length or create binary file for update, default
-                   permissions
-    uw+bx or uwb+x create binary file for update, default permissions
-    ua+b or uab+   append; open or create binary file for update, writing at end-of-file,
-                   default permissions
-6   Opening a file with exclusive mode ('x' as the last character in the mode argument)
-    fails if the file already exists or cannot be created.
-7   To the extent that the underlying system supports the concepts, files opened for writing
-    shall be opened with exclusive (also known as non-shared) access. If the file is being
-    created, and the first character of the mode string is not 'u', to the extent that the
-    underlying system supports it, the file shall have a file permission that prevents other
-    users on the system from accessing the file. If the file is being created and first character
-    of the mode string is 'u', then by the time the file has been closed, it shall have the
-    system default file access permissions.370)
-8   If the file was opened successfully, then the pointer to FILE pointed to by streamptr
-    will be set to the pointer to the object controlling the opened file. Otherwise, the pointer
-
-
-    370) These are the same permissions that the file would have been created with by fopen.
-
-[page 584] (Contents)
-
-    to FILE pointed to by streamptr will be set to a null pointer.
-    Returns
-9   The fopen_s function returns zero if it opened the file. If it did not open the file or if
-    there was a runtime-constraint violation, fopen_s returns a nonzero value.
-    K.3.5.2.2 The freopen_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            errno_t freopen_s(FILE * restrict * restrict newstreamptr,
-                 const char * restrict filename,
-                 const char * restrict mode,
-                 FILE * restrict stream);
-    Runtime-constraints
-2   None of newstreamptr, mode, and stream shall be a null pointer.
-3   If there is a runtime-constraint violation, freopen_s neither attempts to close any file
-    associated with stream nor attempts to open a file. Furthermore, if newstreamptr is
-    not a null pointer, fopen_s sets *newstreamptr to the null pointer.
-    Description
-4   The freopen_s function opens the file whose name is the string pointed to by
-    filename and associates the stream pointed to by stream with it. The mode
-    argument has the same meaning as in the fopen_s function (including the mode's effect
-    on exclusive access and file permissions).
-5   If filename is a null pointer, the freopen_s function attempts to change the mode of
-    the stream to that specified by mode, as if the name of the file currently associated with
-    the stream had been used. It is implementation-defined which changes of mode are
-    permitted (if any), and under what circumstances.
-6   The freopen_s function first attempts to close any file that is associated with stream.
-    Failure to close the file is ignored. The error and end-of-file indicators for the stream are
-    cleared.
-7   If the file was opened successfully, then the pointer to FILE pointed to by
-    newstreamptr will be set to the value of stream. Otherwise, the pointer to FILE
-    pointed to by newstreamptr will be set to a null pointer.
-    Returns
-8   The freopen_s function returns zero if it opened the file. If it did not open the file or
-    there was a runtime-constraint violation, freopen_s returns a nonzero value.
-
-[page 585] (Contents)
-
-    K.3.5.3 Formatted input/output functions
-1   Unless explicitly stated otherwise, if the execution of a function described in this
-    subclause causes copying to take place between objects that overlap, the objects take on
-    unspecified values.
-    K.3.5.3.1 The fprintf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdio.h>
-             int fprintf_s(FILE * restrict stream,
-                  const char * restrict format, ...);
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. The %n specifier371) (modified or
-    not by flags, field width, or precision) shall not appear in the string pointed to by
-    format. Any argument to fprintf_s corresponding to a %s specifier shall not be a
-    null pointer.
-3   If there is a runtime-constraint violation,372) the fprintf_s function does not attempt
-    to produce further output, and it is unspecified to what extent fprintf_s produced
-    output before discovering the runtime-constraint violation.
-    Description
-4   The fprintf_s function is equivalent to the fprintf function except for the explicit
-    runtime-constraints listed above.
-    Returns
-5   The fprintf_s function returns the number of characters transmitted, or a negative
-    value if an output error, encoding error, or runtime-constraint violation occurred.
-
-
-
-
-    371) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-    372) Because an implementation may treat any undefined behavior as a runtime-constraint violation, an
-         implementation may treat any unsupported specifiers in the string pointed to by format as a runtime-
-         constraint violation.
-
-[page 586] (Contents)
-
-    K.3.5.3.2 The fscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            int fscanf_s(FILE * restrict stream,
-                 const char * restrict format, ...);
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. Any argument indirected though in
-    order to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation,373) the fscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent fscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The fscanf_s function is equivalent to fscanf except that the c, s, and [ conversion
-    specifiers apply to a pair of arguments (unless assignment suppression is indicated by a
-    *). The first of these arguments is the same as for fscanf. That argument is
-    immediately followed in the argument list by the second argument, which has type
-    rsize_t and gives the number of elements in the array pointed to by the first argument
-    of the pair. If the first argument points to a scalar object, it is considered to be an array of
-    one element.374)
-5   A matching failure occurs if the number of elements in a receiving object is insufficient to
-    hold the converted input (including any trailing null character).
-    Returns
-6   The fscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-
-    373) Because an implementation may treat any undefined behavior as a runtime-constraint violation, an
-         implementation may treat any unsupported specifiers in the string pointed to by format as a runtime-
-         constraint violation.
-    374) If the format is known at translation time, an implementation may issue a diagnostic for any argument
-         used to store the result from a c, s, or [ conversion specifier if that argument is not followed by an
-         argument of a type compatible with rsize_t. A limited amount of checking may be done if even if
-         the format is not known at translation time. For example, an implementation may issue a diagnostic
-         for each argument after format that has of type pointer to one of char, signed char,
-         unsigned char, or void that is not followed by an argument of a type compatible with
-         rsize_t. The diagnostic could warn that unless the pointer is being used with a conversion specifier
-         using the hh length modifier, a length argument must follow the pointer argument. Another useful
-         diagnostic could flag any non-pointer argument following format that did not have a type
-         compatible with rsize_t.
-
-[page 587] (Contents)
-
-    fscanf_s function returns the number of input items assigned, which can be fewer than
-    provided for, or even zero, in the event of an early matching failure.
-7   EXAMPLE 1        The call:
-             #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdio.h>
-             /* ... */
-             int n, i; float x; char name[50];
-             n = fscanf_s(stdin, "%d%f%s", &i, &x, name, (rsize_t) 50);
-    with the input line:
-             25 54.32E-1 thompson
-    will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
-    thompson\0.
-
-8   EXAMPLE 2        The call:
-             #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdio.h>
-             /* ... */
-             int n; char s[5];
-             n = fscanf_s(stdin, "%s", s, sizeof s);
-    with the input line:
-             hello
-    will assign to n the value 0 since a matching failure occurred because the sequence hello\0 requires an
-    array of six characters to store it.
-
-    K.3.5.3.3 The printf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdio.h>
-             int printf_s(const char * restrict format, ...);
-    Runtime-constraints
-2   format shall not be a null pointer. The %n specifier375) (modified or not by flags, field
-    width, or precision) shall not appear in the string pointed to by format. Any argument
-    to printf_s corresponding to a %s specifier shall not be a null pointer.
-3   If there is a runtime-constraint violation, the printf_s function does not attempt to
-    produce further output, and it is unspecified to what extent printf_s produced output
-    before discovering the runtime-constraint violation.
-
-
-    375) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-
-[page 588] (Contents)
-
-    Description
-4   The printf_s function is equivalent to the printf function except for the explicit
-    runtime-constraints listed above.
-    Returns
-5   The printf_s function returns the number of characters transmitted, or a negative
-    value if an output error, encoding error, or runtime-constraint violation occurred.
-    K.3.5.3.4 The scanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            int scanf_s(const char * restrict format, ...);
-    Runtime-constraints
-2   format shall not be a null pointer. Any argument indirected though in order to store
-    converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the scanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent scanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The scanf_s function is equivalent to fscanf_s with the argument stdin
-    interposed before the arguments to scanf_s.
-    Returns
-5   The scanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    scanf_s function returns the number of input items assigned, which can be fewer than
-    provided for, or even zero, in the event of an early matching failure.
-    K.3.5.3.5 The snprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            int snprintf_s(char * restrict s, rsize_t n,
-                 const char * restrict format, ...);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The %n specifier376) (modified or not by flags, field width, or
-    precision) shall not appear in the string pointed to by format. Any argument to
-[page 589] (Contents)
-
-    snprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding
-    error shall occur.
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the snprintf_s function sets s[0] to the
-    null character.
-    Description
-4   The snprintf_s function is equivalent to the snprintf function except for the
-    explicit runtime-constraints listed above.
-5   The snprintf_s function, unlike sprintf_s, will truncate the result to fit within the
-    array pointed to by s.
-    Returns
-6   The snprintf_s function returns the number of characters that would have been
-    written had n been sufficiently large, not counting the terminating null character, or a
-    negative value if a runtime-constraint violation occurred. Thus, the null-terminated
-    output has been completely written if and only if the returned value is nonnegative and
-    less than n.
-    K.3.5.3.6 The sprintf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdio.h>
-             int sprintf_s(char * restrict s, rsize_t n,
-                  const char * restrict format, ...);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The number of characters (including the trailing null) required for the
-    result to be written to the array pointed to by s shall not be greater than n. The %n
-    specifier377) (modified or not by flags, field width, or precision) shall not appear in the
-    string pointed to by format. Any argument to sprintf_s corresponding to a %s
-    specifier shall not be a null pointer. No encoding error shall occur.
-
-
-
-    376) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-    377) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-
-[page 590] (Contents)
-
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the sprintf_s function sets s[0] to the
-    null character.
-    Description
-4   The sprintf_s function is equivalent to the sprintf function except for the
-    parameter n and the explicit runtime-constraints listed above.
-5   The sprintf_s function, unlike snprintf_s, treats a result too big for the array
-    pointed to by s as a runtime-constraint violation.
-    Returns
-6   If no runtime-constraint violation occurred, the sprintf_s function returns the number
-    of characters written in the array, not counting the terminating null character. If an
-    encoding error occurred, sprintf_s returns a negative value. If any other runtime-
-    constraint violation occurred, sprintf_s returns zero.
-    K.3.5.3.7 The sscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            int sscanf_s(const char * restrict s,
-                 const char * restrict format, ...);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. Any argument indirected though in order
-    to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the sscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent sscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The sscanf_s function is equivalent to fscanf_s, except that input is obtained from
-    a string (specified by the argument s) rather than from a stream. Reaching the end of the
-    string is equivalent to encountering end-of-file for the fscanf_s function. If copying
-    takes place between objects that overlap, the objects take on unspecified values.
-    Returns
-5   The sscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    sscanf_s function returns the number of input items assigned, which can be fewer than
-    provided for, or even zero, in the event of an early matching failure.
-
-[page 591] (Contents)
-
-    K.3.5.3.8 The vfprintf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdarg.h>
-             #include <stdio.h>
-             int vfprintf_s(FILE * restrict stream,
-                  const char * restrict format,
-                  va_list arg);
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. The %n specifier378) (modified or
-    not by flags, field width, or precision) shall not appear in the string pointed to by
-    format. Any argument to vfprintf_s corresponding to a %s specifier shall not be a
-    null pointer.
-3   If there is a runtime-constraint violation, the vfprintf_s function does not attempt to
-    produce further output, and it is unspecified to what extent vfprintf_s produced
-    output before discovering the runtime-constraint violation.
-    Description
-4   The vfprintf_s function is equivalent to the vfprintf function except for the
-    explicit runtime-constraints listed above.
-    Returns
-5   The vfprintf_s function returns the number of characters transmitted, or a negative
-    value if an output error, encoding error, or runtime-constraint violation occurred.
-    K.3.5.3.9 The vfscanf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdarg.h>
-             #include <stdio.h>
-             int vfscanf_s(FILE * restrict stream,
-                  const char * restrict format,
-                  va_list arg);
-
-
-
-
-    378) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-
-[page 592] (Contents)
-
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. Any argument indirected though in
-    order to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vfscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent vfscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The vfscanf_s function is equivalent to fscanf_s, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vfscanf_s function does not invoke the
-    va_end macro.379)
-    Returns
-5   The vfscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    vfscanf_s function returns the number of input items assigned, which can be fewer
-    than provided for, or even zero, in the event of an early matching failure.
-    K.3.5.3.10 The vprintf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdarg.h>
-             #include <stdio.h>
-             int vprintf_s(const char * restrict format,
-                  va_list arg);
-    Runtime-constraints
-2   format shall not be a null pointer. The %n specifier380) (modified or not by flags, field
-    width, or precision) shall not appear in the string pointed to by format. Any argument
-    to vprintf_s corresponding to a %s specifier shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vprintf_s function does not attempt to
-    produce further output, and it is unspecified to what extent vprintf_s produced output
-    before discovering the runtime-constraint violation.
-
-    379) As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s,
-         vsprintf_s, and vsscanf_s invoke the va_arg macro, the value of arg after the return is
-         indeterminate.
-    380) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-
-[page 593] (Contents)
-
-    Description
-4   The vprintf_s function is equivalent to the vprintf function except for the explicit
-    runtime-constraints listed above.
-    Returns
-5   The vprintf_s function returns the number of characters transmitted, or a negative
-    value if an output error, encoding error, or runtime-constraint violation occurred.
-    K.3.5.3.11 The vscanf_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <stdarg.h>
-           #include <stdio.h>
-           int vscanf_s(const char * restrict format,
-                va_list arg);
-    Runtime-constraints
-2   format shall not be a null pointer. Any argument indirected though in order to store
-    converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent vscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The vscanf_s function is equivalent to scanf_s, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vscanf_s function does not invoke the
-    va_end macro.381)
-    Returns
-5   The vscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    vscanf_s function returns the number of input items assigned, which can be fewer than
-    provided for, or even zero, in the event of an early matching failure.
-
-
-
-
-    381) As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s,
-         vsprintf_s, and vsscanf_s invoke the va_arg macro, the value of arg after the return is
-         indeterminate.
-
-[page 594] (Contents)
-
-    K.3.5.3.12 The vsnprintf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdarg.h>
-             #include <stdio.h>
-             int vsnprintf_s(char * restrict s, rsize_t n,
-                  const char * restrict format,
-                  va_list arg);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The %n specifier382) (modified or not by flags, field width, or
-    precision) shall not appear in the string pointed to by format. Any argument to
-    vsnprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding
-    error shall occur.
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the vsnprintf_s function sets s[0] to the
-    null character.
-    Description
-4   The vsnprintf_s function is equivalent to the vsnprintf function except for the
-    explicit runtime-constraints listed above.
-5   The vsnprintf_s function, unlike vsprintf_s, will truncate the result to fit within
-    the array pointed to by s.
-    Returns
-6   The vsnprintf_s function returns the number of characters that would have been
-    written had n been sufficiently large, not counting the terminating null character, or a
-    negative value if a runtime-constraint violation occurred. Thus, the null-terminated
-    output has been completely written if and only if the returned value is nonnegative and
-    less than n.
-
-
-
-
-    382) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-
-[page 595] (Contents)
-
-    K.3.5.3.13 The vsprintf_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdarg.h>
-             #include <stdio.h>
-             int vsprintf_s(char * restrict s, rsize_t n,
-                  const char * restrict format,
-                  va_list arg);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The number of characters (including the trailing null) required for the
-    result to be written to the array pointed to by s shall not be greater than n. The %n
-    specifier383) (modified or not by flags, field width, or precision) shall not appear in the
-    string pointed to by format. Any argument to vsprintf_s corresponding to a %s
-    specifier shall not be a null pointer. No encoding error shall occur.
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the vsprintf_s function sets s[0] to the
-    null character.
-    Description
-4   The vsprintf_s function is equivalent to the vsprintf function except for the
-    parameter n and the explicit runtime-constraints listed above.
-5   The vsprintf_s function, unlike vsnprintf_s, treats a result too big for the array
-    pointed to by s as a runtime-constraint violation.
-    Returns
-6   If no runtime-constraint violation occurred, the vsprintf_s function returns the
-    number of characters written in the array, not counting the terminating null character. If
-    an encoding error occurred, vsprintf_s returns a negative value. If any other
-    runtime-constraint violation occurred, vsprintf_s returns zero.
-
-
-
-
-    383) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
-         at by format when those characters are not a interpreted as a %n specifier. For example, if the entire
-         format string was %%n.
-
-[page 596] (Contents)
-
-    K.3.5.3.14 The vsscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <stdio.h>
-            int vsscanf_s(const char * restrict s,
-                 const char * restrict format,
-                 va_list arg);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. Any argument indirected though in order
-    to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vsscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent vsscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The vsscanf_s function is equivalent to sscanf_s, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vsscanf_s function does not invoke the
-    va_end macro.384)
-    Returns
-5   The vsscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    vscanf_s function returns the number of input items assigned, which can be fewer than
-    provided for, or even zero, in the event of an early matching failure.
-    K.3.5.4 Character input/output functions
-    K.3.5.4.1 The gets_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            char *gets_s(char *s, rsize_t n);
-
-
-
-
-    384) As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s,
-         vsprintf_s, and vsscanf_s invoke the va_arg macro, the value of arg after the return is
-         indeterminate.
-
-[page 597] (Contents)
-
-    Runtime-constraints
-2   s shall not be a null pointer. n shall neither be equal to zero nor be greater than
-    RSIZE_MAX. A new-line character, end-of-file, or read error shall occur within reading
-    n-1 characters from stdin.385)
-3   If there is a runtime-constraint violation, s[0] is set to the null character, and characters
-    are read and discarded from stdin until a new-line character is read, or end-of-file or a
-    read error occurs.
-    Description
-4   The gets_s function reads at most one less than the number of characters specified by n
-    from the stream pointed to by stdin, into the array pointed to by s. No additional
-    characters are read after a new-line character (which is discarded) or after end-of-file.
-    The discarded new-line character does not count towards number of characters read. A
-    null character is written immediately after the last character read into the array.
-5   If end-of-file is encountered and no characters have been read into the array, or if a read
-    error occurs during the operation, then s[0] is set to the null character, and the other
-    elements of s take unspecified values.
-    Recommended practice
-6   The fgets function allows properly-written programs to safely process input lines too
-    long to store in the result array. In general this requires that callers of fgets pay
-    attention to the presence or absence of a new-line character in the result array. Consider
-    using fgets (along with any needed processing based on new-line characters) instead of
-    gets_s.
-    Returns
-7   The gets_s function returns s if successful. If there was a runtime-constraint violation,
-    or if end-of-file is encountered and no characters have been read into the array, or if a
-    read error occurs during the operation, then a null pointer is returned.
-
-
-
-
-    385) The gets_s function, unlike the historical gets function, makes it a runtime-constraint violation for
-         a line of input to overflow the buffer to store it. Unlike the fgets function, gets_s maintains a
-         one-to-one relationship between input lines and successful calls to gets_s. Programs that use gets
-         expect such a relationship.
-
-[page 598] (Contents)
-
-    K.3.6 General utilities <stdlib.h>
-1   The header <stdlib.h> defines three types.
-2   The types are
-            errno_t
-    which is type int; and
-            rsize_t
-    which is the type size_t; and
-            constraint_handler_t
-    which has the following definition
-            typedef void (*constraint_handler_t)(
-                 const char * restrict msg,
-                 void * restrict ptr,
-                 errno_t error);
-    K.3.6.1 Runtime-constraint handling
-    K.3.6.1.1 The set_constraint_handler_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdlib.h>
-            constraint_handler_t set_constraint_handler_s(
-                 constraint_handler_t handler);
-    Description
-2   The set_constraint_handler_s function sets the runtime-constraint handler to
-    be handler. The runtime-constraint handler is the function to be called when a library
-    function detects a runtime-constraint violation. Only the most recent handler registered
-    with set_constraint_handler_s is called when a runtime-constraint violation
-    occurs.
-3   When the handler is called, it is passed the following arguments in the following order:
-       1.   A pointer to a character string describing the runtime-constraint violation.
-       2.   A null pointer or a pointer to an implementation defined object.
-       3.   If the function calling the handler has a return type declared as errno_t, the
-            return value of the function is passed. Otherwise, a positive value of type
-            errno_t is passed.
-
-
-
-[page 599] (Contents)
-
-4   The implementation has a default constraint handler that is used if no calls to the
-    set_constraint_handler_s function have been made. The behavior of the
-    default handler is implementation-defined, and it may cause the program to exit or abort.
-5   If the handler argument to set_constraint_handler_s is a null pointer, the
-    implementation default handler becomes the current constraint handler.
-    Returns
-6   The set_constraint_handler_s function returns a pointer to the previously
-    registered handler.386)
-    K.3.6.1.2 The abort_handler_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdlib.h>
-            void abort_handler_s(
-                 const char * restrict msg,
-                 void * restrict ptr,
-                 errno_t error);
-    Description
-2   A pointer to the abort_handler_s function shall be a suitable argument to the
-    set_constraint_handler_s function.
-3   The abort_handler_s function writes a message on the standard error stream in an
-    implementation-defined format. The message shall include the string pointed to by msg.
-    The abort_handler_s function then calls the abort function.387)
-    Returns
-4   The abort_handler_s function does not return to its caller.
-
-
-
-
-    386) If the previous handler was registered by calling set_constraint_handler_s with a null
-         pointer argument, a pointer to the implementation default handler is returned (not NULL).
-    387) Many implementations invoke a debugger when the abort function is called.
-
-[page 600] (Contents)
-
-    K.3.6.1.3 The ignore_handler_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdlib.h>
-             void ignore_handler_s(
-                  const char * restrict msg,
-                  void * restrict ptr,
-                  errno_t error);
-    Description
-2   A pointer to the ignore_handler_s function shall be a suitable argument to the
-    set_constraint_handler_s function.
-3   The ignore_handler_s function simply returns to its caller.388)
-    Returns
-4   The ignore_handler_s function returns no value.
-    K.3.6.2 Communication with the environment
-    K.3.6.2.1 The getenv_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdlib.h>
-             errno_t getenv_s(size_t * restrict len,
-                        char * restrict value, rsize_t maxsize,
-                        const char * restrict name);
-    Runtime-constraints
-2   name shall not be a null pointer. maxsize shall neither equal zero nor be greater than
-    RSIZE_MAX. If maxsize is not equal to zero, then value shall not be a null pointer.
-3   If there is a runtime-constraint violation, the integer pointed to by len is set to 0 (if len
-    is not null), and the environment list is not searched.
-    Description
-4   The getenv_s function searches an environment list, provided by the host environment,
-    for a string that matches the string pointed to by name.
-
-
-    388) If the runtime-constraint handler is set to the ignore_handler_s function, any library function in
-         which a runtime-constraint violation occurs will return to its caller. The caller can determine whether
-         a runtime-constraint violation occurred based on the library function's specification (usually, the
-         library function returns a nonzero errno_t).
-
-[page 601] (Contents)
-
-5   If that name is found then getenv_s performs the following actions. If len is not a
-    null pointer, the length of the string associated with the matched list member is stored in
-    the integer pointed to by len. If the length of the associated string is less than maxsize,
-    then the associated string is copied to the array pointed to by value.
-6   If that name is not found then getenv_s performs the following actions. If len is not
-    a null pointer, zero is stored in the integer pointed to by len. If maxsize is greater than
-    zero, then value[0] is set to the null character.
-7   The set of environment names and the method for altering the environment list are
-    implementation-defined.
-    Returns
-8   The getenv_s function returns zero if the specified name is found and the associated
-    string was successfully stored in value. Otherwise, a nonzero value is returned.
-    K.3.6.3 Searching and sorting utilities
-1   These utilities make use of a comparison function to search or sort arrays of unspecified
-    type. Where an argument declared as size_t nmemb specifies the length of the array
-    for a function, if nmemb has the value zero on a call to that function, then the comparison
-    function is not called, a search finds no matching element, sorting performs no
-    rearrangement, and the pointer to the array may be null.
-2   The implementation shall ensure that the second argument of the comparison function
-    (when called from bsearch_s), or both arguments (when called from qsort_s), are
-    pointers to elements of the array.389) The first argument when called from bsearch_s
-    shall equal key.
-3   The comparison function shall not alter the contents of either the array or search key. The
-    implementation may reorder elements of the array between calls to the comparison
-    function, but shall not otherwise alter the contents of any individual element.
-4   When the same objects (consisting of size bytes, irrespective of their current positions
-    in the array) are passed more than once to the comparison function, the results shall be
-    consistent with one another. That is, for qsort_s they shall define a total ordering on
-    the array, and for bsearch_s the same object shall always compare the same way with
-    the key.
-
-
-
-
-    389) That is, if the value passed is p, then the following expressions are always valid and nonzero:
-                  ((char *)p - (char *)base) % size == 0
-                  (char *)p >= (char *)base
-                  (char *)p < (char *)base + nmemb * size
-
-
-[page 602] (Contents)
-
-5   A sequence point occurs immediately before and immediately after each call to the
-    comparison function, and also between any call to the comparison function and any
-    movement of the objects passed as arguments to that call.
-    K.3.6.3.1 The bsearch_s function
-    Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <stdlib.h>
-             void *bsearch_s(const void *key, const void *base,
-                  rsize_t nmemb, rsize_t size,
-                  int (*compar)(const void *k, const void *y,
-                                  void *context),
-                  void *context);
-    Runtime-constraints
-2   Neither nmemb nor size shall be greater than RSIZE_MAX. If nmemb is not equal to
-    zero, then none of key, base, or compar shall be a null pointer.
-3   If there is a runtime-constraint violation, the bsearch_s function does not search the
-    array.
-    Description
-4   The bsearch_s function searches an array of nmemb objects, the initial element of
-    which is pointed to by base, for an element that matches the object pointed to by key.
-    The size of each element of the array is specified by size.
-5   The comparison function pointed to by compar is called with three arguments. The first
-    two point to the key object and to an array element, in that order. The function shall
-    return an integer less than, equal to, or greater than zero if the key object is considered,
-    respectively, to be less than, to match, or to be greater than the array element. The array
-    shall consist of: all the elements that compare less than, all the elements that compare
-    equal to, and all the elements that compare greater than the key object, in that order.390)
-    The third argument to the comparison function is the context argument passed to
-    bsearch_s. The sole use of context by bsearch_s is to pass it to the comparison
-    function.391)
-
-
-
-
-    390) In practice, this means that the entire array has been sorted according to the comparison function.
-    391) The context argument is for the use of the comparison function in performing its duties. For
-         example, it might specify a collating sequence used by the comparison function.
-
-[page 603] (Contents)
-
-    Returns
-6   The bsearch_s function returns a pointer to a matching element of the array, or a null
-    pointer if no match is found or there is a runtime-constraint violation. If two elements
-    compare as equal, which element is matched is unspecified.
-    K.3.6.3.2 The qsort_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdlib.h>
-            errno_t qsort_s(void *base, rsize_t nmemb, rsize_t size,
-                 int (*compar)(const void *x, const void *y,
-                                 void *context),
-                 void *context);
-    Runtime-constraints
-2   Neither nmemb nor size shall be greater than RSIZE_MAX. If nmemb is not equal to
-    zero, then neither base nor compar shall be a null pointer.
-3   If there is a runtime-constraint violation, the qsort_s function does not sort the array.
-    Description
-4   The qsort_s function sorts an array of nmemb objects, the initial element of which is
-    pointed to by base. The size of each object is specified by size.
-5   The contents of the array are sorted into ascending order according to a comparison
-    function pointed to by compar, which is called with three arguments. The first two
-    point to the objects being compared. The function shall return an integer less than, equal
-    to, or greater than zero if the first argument is considered to be respectively less than,
-    equal to, or greater than the second. The third argument to the comparison function is the
-    context argument passed to qsort_s. The sole use of context by qsort_s is to
-    pass it to the comparison function.392)
-6   If two elements compare as equal, their relative order in the resulting sorted array is
-    unspecified.
-    Returns
-7   The qsort_s function returns zero if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-
-
-
-
-    392) The context argument is for the use of the comparison function in performing its duties. For
-         example, it might specify a collating sequence used by the comparison function.
-
-[page 604] (Contents)
-
-    K.3.6.4 Multibyte/wide character conversion functions
-1   The behavior of the multibyte character functions is affected by the LC_CTYPE category
-    of the current locale. For a state-dependent encoding, each function is placed into its
-    initial conversion state by a call for which its character pointer argument, s, is a null
-    pointer. Subsequent calls with s as other than a null pointer cause the internal conversion
-    state of the function to be altered as necessary. A call with s as a null pointer causes
-    these functions to set the int pointed to by their status argument to a nonzero value if
-    encodings have state dependency, and zero otherwise.393) Changing the LC_CTYPE
-    category causes the conversion state of these functions to be indeterminate.
-    K.3.6.4.1 The wctomb_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdlib.h>
-            errno_t wctomb_s(int * restrict status,
-                 char * restrict s,
-                 rsize_t smax,
-                 wchar_t wc);
-    Runtime-constraints
-2   Let n denote the number of bytes needed to represent the multibyte character
-    corresponding to the wide character given by wc (including any shift sequences).
-3   If s is not a null pointer, then smax shall not be less than n, and smax shall not be
-    greater than RSIZE_MAX. If s is a null pointer, then smax shall equal zero.
-4   If there is a runtime-constraint violation, wctomb_s does not modify the int pointed to
-    by status, and if s is not a null pointer, no more than smax elements in the array
-    pointed to by s will be accessed.
-    Description
-5   The wctomb_s function determines n and stores the multibyte character representation
-    of wc in the array whose first element is pointed to by s (if s is not a null pointer). The
-    number of characters stored never exceeds MB_CUR_MAX or smax. If wc is a null wide
-    character, a null byte is stored, preceded by any shift sequence needed to restore the
-    initial shift state, and the function is left in the initial conversion state.
-6   The implementation shall behave as if no library function calls the wctomb_s function.
-
-
-
-    393) If the locale employs special bytes to change the shift state, these bytes do not produce separate wide
-         character codes, but are grouped with an adjacent multibyte character.
-
-[page 605] (Contents)
-
-7    If s is a null pointer, the wctomb_s function stores into the int pointed to by status a
-     nonzero or zero value, if multibyte character encodings, respectively, do or do not have
-     state-dependent encodings.
-8    If s is not a null pointer, the wctomb_s function stores into the int pointed to by
-     status either n or -1 if wc, respectively, does or does not correspond to a valid
-     multibyte character.
-9    In no case will the int pointed to by status be set to a value greater than the
-     MB_CUR_MAX macro.
-     Returns
-10   The wctomb_s function returns zero if successful, and a nonzero value if there was a
-     runtime-constraint violation or wc did not correspond to a valid multibyte character.
-     K.3.6.5 Multibyte/wide string conversion functions
-1    The behavior of the multibyte string functions is affected by the LC_CTYPE category of
-     the current locale.
-     K.3.6.5.1 The mbstowcs_s function
-     Synopsis
-1           #include <stdlib.h>
-            errno_t mbstowcs_s(size_t * restrict retval,
-                 wchar_t * restrict dst, rsize_t dstmax,
-                 const char * restrict src, rsize_t len);
-     Runtime-constraints
-2    Neither retval nor src shall be a null pointer. If dst is not a null pointer, then
-     neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null pointer,
-     then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall not equal
-     zero. If dst is not a null pointer and len is not less than dstmax, then a null character
-     shall occur within the first dstmax multibyte characters of the array pointed to by src.
-3    If there is a runtime-constraint violation, then mbstowcs_s does the following. If
-     retval is not a null pointer, then mbstowcs_s sets *retval to (size_t)(-1). If
-     dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
-     then mbstowcs_s sets dst[0] to the null wide character.
-     Description
-4    The mbstowcs_s function converts a sequence of multibyte characters that begins in
-     the initial shift state from the array pointed to by src into a sequence of corresponding
-     wide characters. If dst is not a null pointer, the converted characters are stored into the
-     array pointed to by dst. Conversion continues up to and including a terminating null
-     character, which is also stored. Conversion stops earlier in two cases: when a sequence of
-[page 606] (Contents)
-
-    bytes is encountered that does not form a valid multibyte character, or (if dst is not a
-    null pointer) when len wide characters have been stored into the array pointed to by
-    dst.394) If dst is not a null pointer and no null wide character was stored into the array
-    pointed to by dst, then dst[len] is set to the null wide character. Each conversion
-    takes place as if by a call to the mbrtowc function.
-5   Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
-    sequence of bytes that do not form a valid multibyte character, an encoding error occurs:
-    the mbstowcs_s function stores the value (size_t)(-1) into *retval.
-    Otherwise, the mbstowcs_s function stores into *retval the number of multibyte
-    characters successfully converted, not including the terminating null character (if any).
-6   All elements following the terminating null wide character (if any) written by
-    mbstowcs_s in the array of dstmax wide characters pointed to by dst take
-    unspecified values when mbstowcs_s returns.395)
-7   If copying takes place between objects that overlap, the objects take on unspecified
-    values.
-    Returns
-8   The mbstowcs_s function returns zero if no runtime-constraint violation and no
-    encoding error occurred. Otherwise, a nonzero value is returned.
-    K.3.6.5.2 The wcstombs_s function
-    Synopsis
-1            #include <stdlib.h>
-             errno_t wcstombs_s(size_t * restrict retval,
-                  char * restrict dst, rsize_t dstmax,
-                  const wchar_t * restrict src, rsize_t len);
-    Runtime-constraints
-2   Neither retval nor src shall be a null pointer. If dst is not a null pointer, then
-    neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null pointer,
-    then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall not equal
-    zero. If dst is not a null pointer and len is not less than dstmax, then the conversion
-    shall have been stopped (see below) because a terminating null wide character was
-    reached or because an encoding error occurred.
-
-
-
-
-    394) Thus, the value of len is ignored if dst is a null pointer.
-    395) This allows an implementation to attempt converting the multibyte string before discovering a
-         terminating null character did not occur where required.
-
-[page 607] (Contents)
-
-3   If there is a runtime-constraint violation, then wcstombs_s does the following. If
-    retval is not a null pointer, then wcstombs_s sets *retval to (size_t)(-1). If
-    dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
-    then wcstombs_s sets dst[0] to the null character.
-    Description
-4   The wcstombs_s function converts a sequence of wide characters from the array
-    pointed to by src into a sequence of corresponding multibyte characters that begins in
-    the initial shift state. If dst is not a null pointer, the converted characters are then stored
-    into the array pointed to by dst. Conversion continues up to and including a terminating
-    null wide character, which is also stored. Conversion stops earlier in two cases:
-    -- when a wide character is reached that does not correspond to a valid multibyte
-      character;
-    -- (if dst is not a null pointer) when the next multibyte character would exceed the
-        limit of n total bytes to be stored into the array pointed to by dst. If the wide
-        character being converted is the null wide character, then n is the lesser of len or
-        dstmax. Otherwise, n is the lesser of len or dstmax-1.
-    If the conversion stops without converting a null wide character and dst is not a null
-    pointer, then a null character is stored into the array pointed to by dst immediately
-    following any multibyte characters already stored. Each conversion takes place as if by a
-    call to the wcrtomb function.396)
-5   Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
-    wide character that does not correspond to a valid multibyte character, an encoding error
-    occurs: the wcstombs_s function stores the value (size_t)(-1) into *retval.
-    Otherwise, the wcstombs_s function stores into *retval the number of bytes in the
-    resulting multibyte character sequence, not including the terminating null character (if
-    any).
-6   All elements following the terminating null character (if any) written by wcstombs_s
-    in the array of dstmax elements pointed to by dst take unspecified values when
-    wcstombs_s returns.397)
-7   If copying takes place between objects that overlap, the objects take on unspecified
-    values.
-
-
-    396) If conversion stops because a terminating null wide character has been reached, the bytes stored
-         include those necessary to reach the initial shift state immediately before the null byte. However, if
-         the conversion stops before a terminating null wide character has been reached, the result will be null
-         terminated, but might not end in the initial shift state.
-    397) When len is not less than dstmax, the implementation might fill the array before discovering a
-         runtime-constraint violation.
-
-[page 608] (Contents)
-
-    Returns
-8   The wcstombs_s function returns zero if no runtime-constraint violation and no
-    encoding error occurred. Otherwise, a nonzero value is returned.
-    K.3.7 String handling <string.h>
-1   The header <string.h> defines two types.
-2   The types are
-            errno_t
-    which is type int; and
-            rsize_t
-    which is the type size_t.
-    K.3.7.1 Copying functions
-    K.3.7.1.1 The memcpy_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            errno_t memcpy_s(void * restrict s1, rsize_t s1max,
-                 const void * restrict s2, rsize_t n);
-    Runtime-constraints
-2   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-    RSIZE_MAX. n shall not be greater than s1max. Copying shall not take place between
-    objects that overlap.
-3   If there is a runtime-constraint violation, the memcpy_s function stores zeros in the first
-    s1max characters of the object pointed to by s1 if s1 is not a null pointer and s1max is
-    not greater than RSIZE_MAX.
-    Description
-4   The memcpy_s function copies n characters from the object pointed to by s2 into the
-    object pointed to by s1.
-    Returns
-5   The memcpy_s function returns zero if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-
-
-
-
-[page 609] (Contents)
-
-    K.3.7.1.2 The memmove_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <string.h>
-           errno_t memmove_s(void *s1, rsize_t s1max,
-                const void *s2, rsize_t n);
-    Runtime-constraints
-2   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-    RSIZE_MAX. n shall not be greater than s1max.
-3   If there is a runtime-constraint violation, the memmove_s function stores zeros in the
-    first s1max characters of the object pointed to by s1 if s1 is not a null pointer and
-    s1max is not greater than RSIZE_MAX.
-    Description
-4   The memmove_s function copies n characters from the object pointed to by s2 into the
-    object pointed to by s1. This copying takes place as if the n characters from the object
-    pointed to by s2 are first copied into a temporary array of n characters that does not
-    overlap the objects pointed to by s1 or s2, and then the n characters from the temporary
-    array are copied into the object pointed to by s1.
-    Returns
-5   The memmove_s function returns zero if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-    K.3.7.1.3 The strcpy_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <string.h>
-           errno_t strcpy_s(char * restrict s1,
-                rsize_t s1max,
-                const char * restrict s2);
-    Runtime-constraints
-2   Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
-    s1max shall not equal zero. s1max shall be greater than strnlen_s(s2, s1max).
-    Copying shall not take place between objects that overlap.
-3   If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-    greater than zero and not greater than RSIZE_MAX, then strcpy_s sets s1[0] to the
-    null character.
-
-[page 610] (Contents)
-
-    Description
-4   The strcpy_s function copies the string pointed to by s2 (including the terminating
-    null character) into the array pointed to by s1.
-5   All elements following the terminating null character (if any) written by strcpy_s in
-    the array of s1max characters pointed to by s1 take unspecified values when
-    strcpy_s returns.398)
-    Returns
-6   The strcpy_s function returns zero399) if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-    K.3.7.1.4 The strncpy_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            errno_t strncpy_s(char * restrict s1,
-                 rsize_t s1max,
-                 const char * restrict s2,
-                 rsize_t n);
-    Runtime-constraints
-2   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-    RSIZE_MAX. s1max shall not equal zero. If n is not less than s1max, then s1max
-    shall be greater than strnlen_s(s2, s1max). Copying shall not take place between
-    objects that overlap.
-3   If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-    greater than zero and not greater than RSIZE_MAX, then strncpy_s sets s1[0] to the
-    null character.
-    Description
-4   The strncpy_s function copies not more than n successive characters (characters that
-    follow a null character are not copied) from the array pointed to by s2 to the array
-    pointed to by s1. If no null character was copied from s2, then s1[n] is set to a null
-    character.
-
-
-    398) This allows an implementation to copy characters from s2 to s1 while simultaneously checking if
-         any of those characters are null. Such an approach might write a character to every element of s1
-         before discovering that the first element should be set to the null character.
-    399) A zero return value implies that all of the requested characters from the string pointed to by s2 fit
-         within the array pointed to by s1 and that the result in s1 is null terminated.
-
-[page 611] (Contents)
-
-5   All elements following the terminating null character (if any) written by strncpy_s in
-    the array of s1max characters pointed to by s1 take unspecified values when
-    strncpy_s returns.400)
-    Returns
-6   The strncpy_s function returns zero401) if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-7   EXAMPLE 1 The strncpy_s function can be used to copy a string without the danger that the result
-    will not be null terminated or that characters will be written past the end of the destination array.
-            #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            /* ... */
-            char src1[100] = "hello";
-            char src2[7] = {'g', 'o', 'o', 'd', 'b', 'y', 'e'};
-            char dst1[6], dst2[5], dst3[5];
-            int r1, r2, r3;
-            r1 = strncpy_s(dst1, 6, src1, 100);
-            r2 = strncpy_s(dst2, 5, src2, 7);
-            r3 = strncpy_s(dst3, 5, src2, 4);
-    The first call will assign to r1 the value zero and to dst1 the sequence hello\0.
-    The second call will assign to r2 a nonzero value and to dst2 the sequence \0.
-    The third call will assign to r3 the value zero and to dst3 the sequence good\0.
-
-    K.3.7.2 Concatenation functions
-    K.3.7.2.1 The strcat_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            errno_t strcat_s(char * restrict s1,
-                 rsize_t s1max,
-                 const char * restrict s2);
-    Runtime-constraints
-2   Let m denote the value s1max - strnlen_s(s1, s1max) upon entry to
-    strcat_s.
-
-
-
-
-    400) This allows an implementation to copy characters from s2 to s1 while simultaneously checking if
-         any of those characters are null. Such an approach might write a character to every element of s1
-         before discovering that the first element should be set to the null character.
-    401) A zero return value implies that all of the requested characters from the string pointed to by s2 fit
-         within the array pointed to by s1 and that the result in s1 is null terminated.
-
-[page 612] (Contents)
-
-3   Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
-    s1max shall not equal zero. m shall not equal zero.402) m shall be greater than
-    strnlen_s(s2, m). Copying shall not take place between objects that overlap.
-4   If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-    greater than zero and not greater than RSIZE_MAX, then strcat_s sets s1[0] to the
-    null character.
-    Description
-5   The strcat_s function appends a copy of the string pointed to by s2 (including the
-    terminating null character) to the end of the string pointed to by s1. The initial character
-    from s2 overwrites the null character at the end of s1.
-6   All elements following the terminating null character (if any) written by strcat_s in
-    the array of s1max characters pointed to by s1 take unspecified values when
-    strcat_s returns.403)
-    Returns
-7   The strcat_s function returns zero404) if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-    K.3.7.2.2 The strncat_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            errno_t strncat_s(char * restrict s1,
-                 rsize_t s1max,
-                 const char * restrict s2,
-                 rsize_t n);
-    Runtime-constraints
-2   Let m denote the value s1max - strnlen_s(s1, s1max) upon entry to
-    strncat_s.
-3   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-    RSIZE_MAX. s1max shall not equal zero. m shall not equal zero.405) If n is not less
-
-
-    402) Zero means that s1 was not null terminated upon entry to strcat_s.
-    403) This allows an implementation to append characters from s2 to s1 while simultaneously checking if
-         any of those characters are null. Such an approach might write a character to every element of s1
-         before discovering that the first element should be set to the null character.
-    404) A zero return value implies that all of the requested characters from the string pointed to by s2 were
-         appended to the string pointed to by s1 and that the result in s1 is null terminated.
-
-[page 613] (Contents)
-
-    than m, then m shall be greater than strnlen_s(s2, m). Copying shall not take
-    place between objects that overlap.
-4   If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-    greater than zero and not greater than RSIZE_MAX, then strncat_s sets s1[0] to the
-    null character.
-    Description
-5   The strncat_s function appends not more than n successive characters (characters
-    that follow a null character are not copied) from the array pointed to by s2 to the end of
-    the string pointed to by s1. The initial character from s2 overwrites the null character at
-    the end of s1. If no null character was copied from s2, then s1[s1max-m+n] is set to
-    a null character.
-6   All elements following the terminating null character (if any) written by strncat_s in
-    the array of s1max characters pointed to by s1 take unspecified values when
-    strncat_s returns.406)
-    Returns
-7   The strncat_s function returns zero407) if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-8   EXAMPLE 1 The strncat_s function can be used to copy a string without the danger that the result
-    will not be null terminated or that characters will be written past the end of the destination array.
-            #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            /* ... */
-            char s1[100] = "good";
-            char s2[6] = "hello";
-            char s3[6] = "hello";
-            char s4[7] = "abc";
-            char s5[1000] = "bye";
-            int r1, r2, r3, r4;
-            r1 = strncat_s(s1, 100, s5, 1000);
-            r2 = strncat_s(s2, 6, "", 1);
-            r3 = strncat_s(s3, 6, "X", 2);
-            r4 = strncat_s(s4, 7, "defghijklmn", 3);
-    After the first call r1 will have the value zero and s1 will contain the sequence goodbye\0.
-
-
-
-    405) Zero means that s1 was not null terminated upon entry to strncat_s.
-    406) This allows an implementation to append characters from s2 to s1 while simultaneously checking if
-         any of those characters are null. Such an approach might write a character to every element of s1
-         before discovering that the first element should be set to the null character.
-    407) A zero return value implies that all of the requested characters from the string pointed to by s2 were
-         appended to the string pointed to by s1 and that the result in s1 is null terminated.
-
-[page 614] (Contents)
-
-    After the second call r2 will have the value zero and s2 will contain the sequence hello\0.
-    After the third call r3 will have a nonzero value and s3 will contain the sequence \0.
-    After the fourth call r4 will have the value zero and s4 will contain the sequence abcdef\0.
-
-    K.3.7.3 Search functions
-    K.3.7.3.1 The strtok_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            char *strtok_s(char * restrict s1,
-                 rsize_t * restrict s1max,
-                 const char * restrict s2,
-                 char ** restrict ptr);
-    Runtime-constraints
-2   None of s1max, s2, or ptr shall be a null pointer. If s1 is a null pointer, then *ptr
-    shall not be a null pointer. The value of *s1max shall not be greater than RSIZE_MAX.
-    The end of the token found shall occur within the first *s1max characters of s1 for the
-    first call, and shall occur within the first *s1max characters of where searching resumes
-    on subsequent calls.
-3   If there is a runtime-constraint violation, the strtok_s function does not indirect
-    through the s1 or s2 pointers, and does not store a value in the object pointed to by ptr.
-    Description
-4   A sequence of calls to the strtok_s function breaks the string pointed to by s1 into a
-    sequence of tokens, each of which is delimited by a character from the string pointed to
-    by s2. The fourth argument points to a caller-provided char pointer into which the
-    strtok_s function stores information necessary for it to continue scanning the same
-    string.
-5   The first call in a sequence has a non-null first argument and s1max points to an object
-    whose value is the number of elements in the character array pointed to by the first
-    argument. The first call stores an initial value in the object pointed to by ptr and
-    updates the value pointed to by s1max to reflect the number of elements that remain in
-    relation to ptr. Subsequent calls in the sequence have a null first argument and the
-    objects pointed to by s1max and ptr are required to have the values stored by the
-    previous call in the sequence, which are then updated. The separator string pointed to by
-    s2 may be different from call to call.
-6   The first call in the sequence searches the string pointed to by s1 for the first character
-    that is not contained in the current separator string pointed to by s2. If no such character
-    is found, then there are no tokens in the string pointed to by s1 and the strtok_s
-    function returns a null pointer. If such a character is found, it is the start of the first token.
-[page 615] (Contents)
-
-7    The strtok_s function then searches from there for the first character in s1 that is
-     contained in the current separator string. If no such character is found, the current token
-     extends to the end of the string pointed to by s1, and subsequent searches in the same
-     string for a token return a null pointer. If such a character is found, it is overwritten by a
-     null character, which terminates the current token.
-8    In all cases, the strtok_s function stores sufficient information in the pointer pointed
-     to by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
-     value for ptr, shall start searching just past the element overwritten by a null character
-     (if any).
-     Returns
-9    The strtok_s function returns a pointer to the first character of a token, or a null
-     pointer if there is no token or there is a runtime-constraint violation.
-10   EXAMPLE
-            #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            static char str1[] = "?a???b,,,#c";
-            static char str2[] = "\t \t";
-            char *t, *ptr1, *ptr2;
-            rsize_t max1 = sizeof(str1);
-            rsize_t max2 = sizeof(str2);
-            t   =   strtok_s(str1,   &max1,   "?", &ptr1);         //   t   points to the token "a"
-            t   =   strtok_s(NULL,   &max1,   ",", &ptr1);         //   t   points to the token "??b"
-            t   =   strtok_s(str2,   &max2,   " \t", &ptr2);       //   t   is a null pointer
-            t   =   strtok_s(NULL,   &max1,   "#,", &ptr1);        //   t   points to the token "c"
-            t   =   strtok_s(NULL,   &max1,   "?", &ptr1);         //   t   is a null pointer
-
-     K.3.7.4 Miscellaneous functions
-     K.3.7.4.1 The memset_s function
-     Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            errno_t memset_s(void *s, rsize_t smax, int c, rsize_t n)
-     Runtime-constraints
-2    s shall not be a null pointer. Neither smax nor n shall be greater than RSIZE_MAX. n
-     shall not be greater than smax.
-3    If there is a runtime-constraint violation, then if s is not a null pointer and smax is not
-     greater than RSIZE_MAX, the memset_s function stores the value of c (converted to an
-     unsigned char) into each of the first smax characters of the object pointed to by s.
-
-
-
-[page 616] (Contents)
-
-    Description
-4   The memset_s function copies the value of c (converted to an unsigned char) into
-    each of the first n characters of the object pointed to by s. Unlike memset, any call to
-    the memset_s function shall be evaluated strictly according to the rules of the abstract
-    machine as described in (5.1.2.3). That is, any call to the memset_s function shall
-    assume that the memory indicated by s and n may be accessible in the future and thus
-    must contain the values indicated by c.
-    Returns
-5   The memset_s function returns zero if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-    K.3.7.4.2 The strerror_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            errno_t strerror_s(char *s, rsize_t maxsize,
-                 errno_t errnum);
-    Runtime-constraints
-2   s shall not be a null pointer. maxsize shall not be greater than RSIZE_MAX.
-    maxsize shall not equal zero.
-3   If there is a runtime-constraint violation, then the array (if any) pointed to by s is not
-    modified.
-    Description
-4   The strerror_s function maps the number in errnum to a locale-specific message
-    string. Typically, the values for errnum come from errno, but strerror_s shall
-    map any value of type int to a message.
-5   If the length of the desired string is less than maxsize, then the string is copied to the
-    array pointed to by s.
-6   Otherwise, if maxsize is greater than zero, then maxsize-1 characters are copied
-    from the string to the array pointed to by s and then s[maxsize-1] is set to the null
-    character. Then, if maxsize is greater than 3, then s[maxsize-2],
-    s[maxsize-3], and s[maxsize-4] are set to the character period (.).
-    Returns
-7   The strerror_s function returns zero if the length of the desired string was less than
-    maxsize and there was no runtime-constraint violation. Otherwise, the strerror_s
-    function returns a nonzero value.
-
-[page 617] (Contents)
-
-    K.3.7.4.3 The strerrorlen_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            size_t strerrorlen_s(errno_t errnum);
-    Description
-2   The strerrorlen_s function calculates the length of the (untruncated) locale-specific
-    message string that the strerror_s function maps to errnum.
-    Returns
-3   The strerrorlen_s function returns the number of characters (not including the null
-    character) in the full message string.
-    K.3.7.4.4 The strnlen_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <string.h>
-            size_t strnlen_s(const char *s, size_t maxsize);
-    Description
-2   The strnlen_s function computes the length of the string pointed to by s.
-    Returns
-3   If s is a null pointer,408) then the strnlen_s function returns zero.
-4   Otherwise, the strnlen_s function returns the number of characters that precede the
-    terminating null character. If there is no null character in the first maxsize characters of
-    s then strnlen_s returns maxsize. At most the first maxsize characters of s shall
-    be accessed by strnlen_s.
-
-
-
-
-    408) Note that the strnlen_s function has no runtime-constraints. This lack of runtime-constraints
-         along with the values returned for a null pointer or an unterminated string argument make
-         strnlen_s useful in algorithms that gracefully handle such exceptional data.
-
-[page 618] (Contents)
-
-    K.3.8 Date and time <time.h>
-1   The header <time.h> defines two types.
-2   The types are
-            errno_t
-    which is type int; and
-            rsize_t
-    which is the type size_t.
-    K.3.8.1 Components of time
-1   A broken-down time is normalized if the values of the members of the tm structure are in
-    their normal rages.409)
-    K.3.8.2 Time conversion functions
-1   Like the strftime function, the asctime_s and ctime_s functions do not return a
-    pointer to a static object, and other library functions are permitted to call them.
-    K.3.8.2.1 The asctime_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <time.h>
-            errno_t asctime_s(char *s, rsize_t maxsize,
-                 const struct tm *timeptr);
-    Runtime-constraints
-2   Neither s nor timeptr shall be a null pointer. maxsize shall not be less than 26 and
-    shall not be greater than RSIZE_MAX. The broken-down time pointed to by timeptr
-    shall be normalized. The calendar year represented by the broken-down time pointed to
-    by timeptr shall not be less than calendar year 0 and shall not be greater than calendar
-    year 9999.
-3   If there is a runtime-constraint violation, there is no attempt to convert the time, and
-    s[0] is set to a null character if s is not a null pointer and maxsize is not zero and is
-    not greater than RSIZE_MAX.
-    Description
-4   The asctime_s function converts the normalized broken-down time in the structure
-    pointed to by timeptr into a 26 character (including the null character) string in the
-
-
-    409) The normal ranges are defined in 7.26.1.
-
-[page 619] (Contents)
-
-    form
-            Sun Sep 16 01:03:52 1973\n\0
-    The fields making up this string are (in order):
-       1.   The name of the day of the week represented by timeptr->tm_wday using the
-            following three character weekday names: Sun, Mon, Tue, Wed, Thu, Fri, and Sat.
-       2.   The character space.
-       3. The name of the month represented by timeptr->tm_mon using the following
-          three character month names: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct,
-          Nov, and Dec.
-       4.   The character space.
-       5.   The value of timeptr->tm_mday as if printed using the fprintf format
-            "%2d".
-       6.   The character space.
-       7.   The value of timeptr->tm_hour as if printed using the fprintf format
-            "%.2d".
-       8.   The character colon.
-       9.   The value of timeptr->tm_min as if printed using the fprintf format
-            "%.2d".
-     10.    The character colon.
-     11.    The value of timeptr->tm_sec as if printed using the fprintf format
-            "%.2d".
-     12.    The character space.
-     13.    The value of timeptr->tm_year + 1900 as if printed using the fprintf
-            format "%4d".
-     14.    The character new line.
-     15.    The null character.
-    Recommended practice
-    The strftime function allows more flexible formatting and supports locale-specific
-    behavior. If you do not require the exact form of the result string produced by the
-    asctime_s function, consider using the strftime function instead.
-    Returns
-5   The asctime_s function returns zero if the time was successfully converted and stored
-    into the array pointed to by s. Otherwise, it returns a nonzero value.
-[page 620] (Contents)
-
-    K.3.8.2.2 The ctime_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <time.h>
-            errno_t ctime_s(char *s, rsize_t maxsize,
-                 const time_t *timer);
-    Runtime-constraints
-2   Neither s nor timer shall be a null pointer. maxsize shall not be less than 26 and
-    shall not be greater than RSIZE_MAX.
-3   If there is a runtime-constraint violation, s[0] is set to a null character if s is not a null
-    pointer and maxsize is not equal zero and is not greater than RSIZE_MAX.
-    Description
-4   The ctime_s function converts the calendar time pointed to by timer to local time in
-    the form of a string. It is equivalent to
-            asctime_s(s, maxsize, localtime_s(timer))
-    Recommended practice
-    The strftime function allows more flexible formatting and supports locale-specific
-    behavior. If you do not require the exact form of the result string produced by the
-    ctime_s function, consider using the strftime function instead.
-    Returns
-5   The ctime_s function returns zero if the time was successfully converted and stored
-    into the array pointed to by s. Otherwise, it returns a nonzero value.
-    K.3.8.2.3 The gmtime_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <time.h>
-            struct tm *gmtime_s(const time_t * restrict timer,
-                 struct tm * restrict result);
-    Runtime-constraints
-2   Neither timer nor result shall be a null pointer.
-3   If there is a runtime-constraint violation, there is no attempt to convert the time.
-    Description
-4   The gmtime_s function converts the calendar time pointed to by timer into a broken-
-    down time, expressed as UTC. The broken-down time is stored in the structure pointed
-[page 621] (Contents)
-
-    to by result.
-    Returns
-5   The gmtime_s function returns result, or a null pointer if the specified time cannot
-    be converted to UTC or there is a runtime-constraint violation.
-    K.3.8.2.4 The localtime_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <time.h>
-           struct tm *localtime_s(const time_t * restrict timer,
-                struct tm * restrict result);
-    Runtime-constraints
-2   Neither timer nor result shall be a null pointer.
-3   If there is a runtime-constraint violation, there is no attempt to convert the time.
-    Description
-4   The localtime_s function converts the calendar time pointed to by timer into a
-    broken-down time, expressed as local time. The broken-down time is stored in the
-    structure pointed to by result.
-    Returns
-5   The localtime_s function returns result, or a null pointer if the specified time
-    cannot be converted to local time or there is a runtime-constraint violation.
-    K.3.9 Extended multibyte and wide character utilities <wchar.h>
-1   The header <wchar.h> defines two types.
-2   The types are
-           errno_t
-    which is type int; and
-           rsize_t
-    which is the type size_t.
-3   Unless explicitly stated otherwise, if the execution of a function described in this
-    subclause causes copying to take place between objects that overlap, the objects take on
-    unspecified values.
-
-
-
-
-[page 622] (Contents)
-
-    K.3.9.1 Formatted wide character input/output functions
-    K.3.9.1.1 The fwprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <wchar.h>
-            int fwprintf_s(FILE * restrict stream,
-                 const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. The %n specifier410) (modified or
-    not by flags, field width, or precision) shall not appear in the wide string pointed to by
-    format. Any argument to fwprintf_s corresponding to a %s specifier shall not be a
-    null pointer.
-3   If there is a runtime-constraint violation, the fwprintf_s function does not attempt to
-    produce further output, and it is unspecified to what extent fwprintf_s produced
-    output before discovering the runtime-constraint violation.
-    Description
-4   The fwprintf_s function is equivalent to the fwprintf function except for the
-    explicit runtime-constraints listed above.
-    Returns
-5   The fwprintf_s function returns the number of wide characters transmitted, or a
-    negative value if an output error, encoding error, or runtime-constraint violation occurred.
-    K.3.9.1.2 The fwscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdio.h>
-            #include <wchar.h>
-            int fwscanf_s(FILE * restrict stream,
-                 const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. Any argument indirected though in
-    order to store converted input shall not be a null pointer.
-
-
-    410) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 623] (Contents)
-
-3   If there is a runtime-constraint violation, the fwscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent fwscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The fwscanf_s function is equivalent to fwscanf except that the c, s, and [
-    conversion specifiers apply to a pair of arguments (unless assignment suppression is
-    indicated by a *). The first of these arguments is the same as for fwscanf. That
-    argument is immediately followed in the argument list by the second argument, which has
-    type size_t and gives the number of elements in the array pointed to by the first
-    argument of the pair. If the first argument points to a scalar object, it is considered to be
-    an array of one element.411)
-5   A matching failure occurs if the number of elements in a receiving object is insufficient to
-    hold the converted input (including any trailing null character).
-    Returns
-6   The fwscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    fwscanf_s function returns the number of input items assigned, which can be fewer
-    than provided for, or even zero, in the event of an early matching failure.
-    K.3.9.1.3 The snwprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <wchar.h>
-            int snwprintf_s(wchar_t * restrict s,
-                 rsize_t n,
-                 const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The %n specifier412) (modified or not by flags, field width, or
-
-    411) If the format is known at translation time, an implementation may issue a diagnostic for any argument
-         used to store the result from a c, s, or [ conversion specifier if that argument is not followed by an
-         argument of a type compatible with rsize_t. A limited amount of checking may be done if even if
-         the format is not known at translation time. For example, an implementation may issue a diagnostic
-         for each argument after format that has of type pointer to one of char, signed char,
-         unsigned char, or void that is not followed by an argument of a type compatible with
-         rsize_t. The diagnostic could warn that unless the pointer is being used with a conversion specifier
-         using the hh length modifier, a length argument must follow the pointer argument. Another useful
-         diagnostic could flag any non-pointer argument following format that did not have a type
-         compatible with rsize_t.
-
-[page 624] (Contents)
-
-    precision) shall not appear in the wide string pointed to by format. Any argument to
-    snwprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding
-    error shall occur.
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the snwprintf_s function sets s[0] to the
-    null wide character.
-    Description
-4   The snwprintf_s function is equivalent to the swprintf function except for the
-    explicit runtime-constraints listed above.
-5   The snwprintf_s function, unlike swprintf_s, will truncate the result to fit within
-    the array pointed to by s.
-    Returns
-6   The snwprintf_s function returns the number of wide characters that would have
-    been written had n been sufficiently large, not counting the terminating wide null
-    character, or a negative value if a runtime-constraint violation occurred. Thus, the null-
-    terminated output has been completely written if and only if the returned value is
-    nonnegative and less than n.
-    K.3.9.1.4 The swprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <wchar.h>
-            int swprintf_s(wchar_t * restrict s, rsize_t n,
-                 const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The number of wide characters (including the trailing null) required
-    for the result to be written to the array pointed to by s shall not be greater than n. The %n
-    specifier413) (modified or not by flags, field width, or precision) shall not appear in the
-    wide string pointed to by format. Any argument to swprintf_s corresponding to a
-    %s specifier shall not be a null pointer. No encoding error shall occur.
-
-
-    412) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-    413) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 625] (Contents)
-
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the swprintf_s function sets s[0] to the
-    null wide character.
-    Description
-4   The swprintf_s function is equivalent to the swprintf function except for the
-    explicit runtime-constraints listed above.
-5   The swprintf_s function, unlike snwprintf_s, treats a result too big for the array
-    pointed to by s as a runtime-constraint violation.
-    Returns
-6   If no runtime-constraint violation occurred, the swprintf_s function returns the
-    number of wide characters written in the array, not counting the terminating null wide
-    character. If an encoding error occurred or if n or more wide characters are requested to
-    be written, swprintf_s returns a negative value. If any other runtime-constraint
-    violation occurred, swprintf_s returns zero.
-    K.3.9.1.5 The swscanf_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <wchar.h>
-           int swscanf_s(const wchar_t * restrict s,
-                const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. Any argument indirected though in order
-    to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the swscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent swscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The swscanf_s function is equivalent to fwscanf_s, except that the argument s
-    specifies a wide string from which the input is to be obtained, rather than from a stream.
-    Reaching the end of the wide string is equivalent to encountering end-of-file for the
-    fwscanf_s function.
-    Returns
-5   The swscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    swscanf_s function returns the number of input items assigned, which can be fewer
-    than provided for, or even zero, in the event of an early matching failure.
-[page 626] (Contents)
-
-    K.3.9.1.6 The vfwprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <stdio.h>
-            #include <wchar.h>
-            int vfwprintf_s(FILE * restrict stream,
-                 const wchar_t * restrict format,
-                 va_list arg);
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. The %n specifier414) (modified or
-    not by flags, field width, or precision) shall not appear in the wide string pointed to by
-    format. Any argument to vfwprintf_s corresponding to a %s specifier shall not be
-    a null pointer.
-3   If there is a runtime-constraint violation, the vfwprintf_s function does not attempt
-    to produce further output, and it is unspecified to what extent vfwprintf_s produced
-    output before discovering the runtime-constraint violation.
-    Description
-4   The vfwprintf_s function is equivalent to the vfwprintf function except for the
-    explicit runtime-constraints listed above.
-    Returns
-5   The vfwprintf_s function returns the number of wide characters transmitted, or a
-    negative value if an output error, encoding error, or runtime-constraint violation occurred.
-    K.3.9.1.7 The vfwscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <stdio.h>
-            #include <wchar.h>
-            int vfwscanf_s(FILE * restrict stream,
-                 const wchar_t * restrict format, va_list arg);
-
-
-
-    414) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 627] (Contents)
-
-    Runtime-constraints
-2   Neither stream nor format shall be a null pointer. Any argument indirected though in
-    order to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vfwscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent vfwscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The vfwscanf_s function is equivalent to fwscanf_s, with the variable argument
-    list replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vfwscanf_s function does not invoke the
-    va_end macro.415)
-    Returns
-5   The vfwscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    vfwscanf_s function returns the number of input items assigned, which can be fewer
-    than provided for, or even zero, in the event of an early matching failure.
-    K.3.9.1.8 The vsnwprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <wchar.h>
-            int vsnwprintf_s(wchar_t * restrict s,
-                 rsize_t n,
-                 const wchar_t * restrict format,
-                 va_list arg);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The %n specifier416) (modified or not by flags, field width, or
-    precision) shall not appear in the wide string pointed to by format. Any argument to
-    vsnwprintf_s corresponding to a %s specifier shall not be a null pointer. No
-    encoding error shall occur.
-
-    415) As the functions vfwscanf_s, vwscanf_s, and vswscanf_s invoke the va_arg macro, the
-         value of arg after the return is indeterminate.
-    416) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 628] (Contents)
-
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the vsnwprintf_s function sets s[0] to
-    the null wide character.
-    Description
-4   The vsnwprintf_s function is equivalent to the vswprintf function except for the
-    explicit runtime-constraints listed above.
-5   The vsnwprintf_s function, unlike vswprintf_s, will truncate the result to fit
-    within the array pointed to by s.
-    Returns
-6   The vsnwprintf_s function returns the number of wide characters that would have
-    been written had n been sufficiently large, not counting the terminating null character, or
-    a negative value if a runtime-constraint violation occurred. Thus, the null-terminated
-    output has been completely written if and only if the returned value is nonnegative and
-    less than n.
-    K.3.9.1.9 The vswprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <wchar.h>
-            int vswprintf_s(wchar_t * restrict s,
-                 rsize_t n,
-                 const wchar_t * restrict format,
-                 va_list arg);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
-    than RSIZE_MAX. The number of wide characters (including the trailing null) required
-    for the result to be written to the array pointed to by s shall not be greater than n. The %n
-    specifier417) (modified or not by flags, field width, or precision) shall not appear in the
-    wide string pointed to by format. Any argument to vswprintf_s corresponding to a
-    %s specifier shall not be a null pointer. No encoding error shall occur.
-3   If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
-    than zero and less than RSIZE_MAX, then the vswprintf_s function sets s[0] to the
-    null wide character.
-
-    417) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 629] (Contents)
-
-    Description
-4   The vswprintf_s function is equivalent to the vswprintf function except for the
-    explicit runtime-constraints listed above.
-5   The vswprintf_s function, unlike vsnwprintf_s, treats a result too big for the
-    array pointed to by s as a runtime-constraint violation.
-    Returns
-6   If no runtime-constraint violation occurred, the vswprintf_s function returns the
-    number of wide characters written in the array, not counting the terminating null wide
-    character. If an encoding error occurred or if n or more wide characters are requested to
-    be written, vswprintf_s returns a negative value. If any other runtime-constraint
-    violation occurred, vswprintf_s returns zero.
-    K.3.9.1.10 The vswscanf_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <stdarg.h>
-           #include <wchar.h>
-           int vswscanf_s(const wchar_t * restrict s,
-                const wchar_t * restrict format,
-                va_list arg);
-    Runtime-constraints
-2   Neither s nor format shall be a null pointer. Any argument indirected though in order
-    to store converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vswscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent vswscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The vswscanf_s function is equivalent to swscanf_s, with the variable argument
-    list replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vswscanf_s function does not invoke the
-    va_end macro.418)
-
-
-
-
-    418) As the functions vfwscanf_s, vwscanf_s, and vswscanf_s invoke the va_arg macro, the
-         value of arg after the return is indeterminate.
-
-[page 630] (Contents)
-
-    Returns
-5   The vswscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    vswscanf_s function returns the number of input items assigned, which can be fewer
-    than provided for, or even zero, in the event of an early matching failure.
-    K.3.9.1.11 The vwprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <wchar.h>
-            int vwprintf_s(const wchar_t * restrict format,
-                 va_list arg);
-    Runtime-constraints
-2   format shall not be a null pointer. The %n specifier419) (modified or not by flags, field
-    width, or precision) shall not appear in the wide string pointed to by format. Any
-    argument to vwprintf_s corresponding to a %s specifier shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vwprintf_s function does not attempt to
-    produce further output, and it is unspecified to what extent vwprintf_s produced
-    output before discovering the runtime-constraint violation.
-    Description
-4   The vwprintf_s function is equivalent to the vwprintf function except for the
-    explicit runtime-constraints listed above.
-    Returns
-5   The vwprintf_s function returns the number of wide characters transmitted, or a
-    negative value if an output error, encoding error, or runtime-constraint violation occurred.
-
-
-
-
-    419) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 631] (Contents)
-
-    K.3.9.1.12 The vwscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <stdarg.h>
-            #include <wchar.h>
-            int vwscanf_s(const wchar_t * restrict format,
-                 va_list arg);
-    Runtime-constraints
-2   format shall not be a null pointer. Any argument indirected though in order to store
-    converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the vwscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent vwscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The vwscanf_s function is equivalent to wscanf_s, with the variable argument list
-    replaced by arg, which shall have been initialized by the va_start macro (and
-    possibly subsequent va_arg calls). The vwscanf_s function does not invoke the
-    va_end macro.420)
-    Returns
-5   The vwscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    vwscanf_s function returns the number of input items assigned, which can be fewer
-    than provided for, or even zero, in the event of an early matching failure.
-    K.3.9.1.13 The wprintf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <wchar.h>
-            int wprintf_s(const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   format shall not be a null pointer. The %n specifier421) (modified or not by flags, field
-
-    420) As the functions vfwscanf_s, vwscanf_s, and vswscanf_s invoke the va_arg macro, the
-         value of arg after the return is indeterminate.
-    421) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
-         string pointed at by format when those wide characters are not a interpreted as a %n specifier. For
-         example, if the entire format string was L"%%n".
-
-[page 632] (Contents)
-
-    width, or precision) shall not appear in the wide string pointed to by format. Any
-    argument to wprintf_s corresponding to a %s specifier shall not be a null pointer.
-3   If there is a runtime-constraint violation, the wprintf_s function does not attempt to
-    produce further output, and it is unspecified to what extent wprintf_s produced output
-    before discovering the runtime-constraint violation.
-    Description
-4   The wprintf_s function is equivalent to the wprintf function except for the explicit
-    runtime-constraints listed above.
-    Returns
-5   The wprintf_s function returns the number of wide characters transmitted, or a
-    negative value if an output error, encoding error, or runtime-constraint violation occurred.
-    K.3.9.1.14 The wscanf_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <wchar.h>
-            int wscanf_s(const wchar_t * restrict format, ...);
-    Runtime-constraints
-2   format shall not be a null pointer. Any argument indirected though in order to store
-    converted input shall not be a null pointer.
-3   If there is a runtime-constraint violation, the wscanf_s function does not attempt to
-    perform further input, and it is unspecified to what extent wscanf_s performed input
-    before discovering the runtime-constraint violation.
-    Description
-4   The wscanf_s function is equivalent to fwscanf_s with the argument stdin
-    interposed before the arguments to wscanf_s.
-    Returns
-5   The wscanf_s function returns the value of the macro EOF if an input failure occurs
-    before any conversion or if there is a runtime-constraint violation. Otherwise, the
-    wscanf_s function returns the number of input items assigned, which can be fewer than
-    provided for, or even zero, in the event of an early matching failure.
-
-
-
-
-[page 633] (Contents)
-
-    K.3.9.2 General wide string utilities
-    K.3.9.2.1 Wide string copying functions
-    K.3.9.2.1.1 The wcscpy_s function
-    Synopsis
-1           #define __STDC_WANT_LIB_EXT1__ 1
-            #include <wchar.h>
-            errno_t wcscpy_s(wchar_t * restrict s1,
-                 rsize_t s1max,
-                 const wchar_t * restrict s2);
-    Runtime-constraints
-2   Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
-    s1max shall not equal zero. s1max shall be greater than wcsnlen_s(s2, s1max).
-    Copying shall not take place between objects that overlap.
-3   If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-    greater than zero and not greater than RSIZE_MAX, then wcscpy_s sets s1[0] to the
-    null wide character.
-    Description
-4   The wcscpy_s function copies the wide string pointed to by s2 (including the
-    terminating null wide character) into the array pointed to by s1.
-5   All elements following the terminating null wide character (if any) written by
-    wcscpy_s in the array of s1max wide characters pointed to by s1 take unspecified
-    values when wcscpy_s returns.422)
-    Returns
-6   The wcscpy_s function returns zero423) if there was no runtime-constraint violation.
-    Otherwise, a nonzero value is returned.
-
-
-
-
-    422) This allows an implementation to copy wide characters from s2 to s1 while simultaneously checking
-         if any of those wide characters are null. Such an approach might write a wide character to every
-         element of s1 before discovering that the first element should be set to the null wide character.
-    423) A zero return value implies that all of the requested wide characters from the string pointed to by s2
-         fit within the array pointed to by s1 and that the result in s1 is null terminated.
-
-[page 634] (Contents)
-
-     K.3.9.2.1.2 The wcsncpy_s function
-     Synopsis
-7            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             errno_t wcsncpy_s(wchar_t * restrict s1,
-                  rsize_t s1max,
-                  const wchar_t * restrict s2,
-                  rsize_t n);
-     Runtime-constraints
-8    Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-     RSIZE_MAX. s1max shall not equal zero. If n is not less than s1max, then s1max
-     shall be greater than wcsnlen_s(s2, s1max). Copying shall not take place between
-     objects that overlap.
-9    If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-     greater than zero and not greater than RSIZE_MAX, then wcsncpy_s sets s1[0] to the
-     null wide character.
-     Description
-10   The wcsncpy_s function copies not more than n successive wide characters (wide
-     characters that follow a null wide character are not copied) from the array pointed to by
-     s2 to the array pointed to by s1. If no null wide character was copied from s2, then
-     s1[n] is set to a null wide character.
-11   All elements following the terminating null wide character (if any) written by
-     wcsncpy_s in the array of s1max wide characters pointed to by s1 take unspecified
-     values when wcsncpy_s returns.424)
-     Returns
-12   The wcsncpy_s function returns zero425) if there was no runtime-constraint violation.
-     Otherwise, a nonzero value is returned.
-13   EXAMPLE 1 The wcsncpy_s function can be used to copy a wide string without the danger that the
-     result will not be null terminated or that wide characters will be written past the end of the destination
-     array.
-
-
-
-
-     424) This allows an implementation to copy wide characters from s2 to s1 while simultaneously checking
-          if any of those wide characters are null. Such an approach might write a wide character to every
-          element of s1 before discovering that the first element should be set to the null wide character.
-     425) A zero return value implies that all of the requested wide characters from the string pointed to by s2
-          fit within the array pointed to by s1 and that the result in s1 is null terminated.
-
-[page 635] (Contents)
-
-             #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             /* ... */
-             wchar_t src1[100] = L"hello";
-             wchar_t src2[7] = {L'g', L'o', L'o', L'd', L'b', L'y', L'e'};
-             wchar_t dst1[6], dst2[5], dst3[5];
-             int r1, r2, r3;
-             r1 = wcsncpy_s(dst1, 6, src1, 100);
-             r2 = wcsncpy_s(dst2, 5, src2, 7);
-             r3 = wcsncpy_s(dst3, 5, src2, 4);
-     The first call will assign to r1 the value zero and to dst1 the sequence of wide characters hello\0.
-     The second call will assign to r2 a nonzero value and to dst2 the sequence of wide characters \0.
-     The third call will assign to r3 the value zero and to dst3 the sequence of wide characters good\0.
-
-     K.3.9.2.1.3 The wmemcpy_s function
-     Synopsis
-14           #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             errno_t wmemcpy_s(wchar_t * restrict s1,
-                  rsize_t s1max,
-                  const wchar_t * restrict s2,
-                  rsize_t n);
-     Runtime-constraints
-15   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-     RSIZE_MAX. n shall not be greater than s1max. Copying shall not take place between
-     objects that overlap.
-16   If there is a runtime-constraint violation, the wmemcpy_s function stores zeros in the
-     first s1max wide characters of the object pointed to by s1 if s1 is not a null pointer and
-     s1max is not greater than RSIZE_MAX.
-     Description
-17   The wmemcpy_s function copies n successive wide characters from the object pointed
-     to by s2 into the object pointed to by s1.
-     Returns
-18   The wmemcpy_s function returns zero if there was no runtime-constraint violation.
-     Otherwise, a nonzero value is returned.
-
-
-
-
-[page 636] (Contents)
-
-     K.3.9.2.1.4 The wmemmove_s function
-     Synopsis
-19           #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             errno_t wmemmove_s(wchar_t *s1, rsize_t s1max,
-                  const wchar_t *s2, rsize_t n);
-     Runtime-constraints
-20   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-     RSIZE_MAX. n shall not be greater than s1max.
-21   If there is a runtime-constraint violation, the wmemmove_s function stores zeros in the
-     first s1max wide characters of the object pointed to by s1 if s1 is not a null pointer and
-     s1max is not greater than RSIZE_MAX.
-     Description
-22   The wmemmove_s function copies n successive wide characters from the object pointed
-     to by s2 into the object pointed to by s1. This copying takes place as if the n wide
-     characters from the object pointed to by s2 are first copied into a temporary array of n
-     wide characters that does not overlap the objects pointed to by s1 or s2, and then the n
-     wide characters from the temporary array are copied into the object pointed to by s1.
-     Returns
-23   The wmemmove_s function returns zero if there was no runtime-constraint violation.
-     Otherwise, a nonzero value is returned.
-     K.3.9.2.2 Wide string concatenation functions
-     K.3.9.2.2.1 The wcscat_s function
-     Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             errno_t wcscat_s(wchar_t * restrict s1,
-                  rsize_t s1max,
-                  const wchar_t * restrict s2);
-     Runtime-constraints
-2    Let m denote the value s1max - wcsnlen_s(s1, s1max) upon entry to
-     wcscat_s.
-3    Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
-     s1max shall not equal zero. m shall not equal zero.426) m shall be greater than
-     wcsnlen_s(s2, m). Copying shall not take place between objects that overlap.
-
-[page 637] (Contents)
-
-4    If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-     greater than zero and not greater than RSIZE_MAX, then wcscat_s sets s1[0] to the
-     null wide character.
-     Description
-5    The wcscat_s function appends a copy of the wide string pointed to by s2 (including
-     the terminating null wide character) to the end of the wide string pointed to by s1. The
-     initial wide character from s2 overwrites the null wide character at the end of s1.
-6    All elements following the terminating null wide character (if any) written by
-     wcscat_s in the array of s1max wide characters pointed to by s1 take unspecified
-     values when wcscat_s returns.427)
-     Returns
-7    The wcscat_s function returns zero428) if there was no runtime-constraint violation.
-     Otherwise, a nonzero value is returned.
-     K.3.9.2.2.2 The wcsncat_s function
-     Synopsis
-8             #define __STDC_WANT_LIB_EXT1__ 1
-              #include <wchar.h>
-              errno_t wcsncat_s(wchar_t * restrict s1,
-                   rsize_t s1max,
-                   const wchar_t * restrict s2,
-                   rsize_t n);
-     Runtime-constraints
-9    Let m denote the value s1max - wcsnlen_s(s1, s1max) upon entry to
-     wcsncat_s.
-10   Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
-     RSIZE_MAX. s1max shall not equal zero. m shall not equal zero.429) If n is not less
-     than m, then m shall be greater than wcsnlen_s(s2, m). Copying shall not take
-     place between objects that overlap.
-
-
-     426) Zero means that s1 was not null terminated upon entry to wcscat_s.
-     427) This allows an implementation to append wide characters from s2 to s1 while simultaneously
-          checking if any of those wide characters are null. Such an approach might write a wide character to
-          every element of s1 before discovering that the first element should be set to the null wide character.
-     428) A zero return value implies that all of the requested wide characters from the wide string pointed to by
-          s2 were appended to the wide string pointed to by s1 and that the result in s1 is null terminated.
-     429) Zero means that s1 was not null terminated upon entry to wcsncat_s.
-
-[page 638] (Contents)
-
-11   If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
-     greater than zero and not greater than RSIZE_MAX, then wcsncat_s sets s1[0] to the
-     null wide character.
-     Description
-12   The wcsncat_s function appends not more than n successive wide characters (wide
-     characters that follow a null wide character are not copied) from the array pointed to by
-     s2 to the end of the wide string pointed to by s1. The initial wide character from s2
-     overwrites the null wide character at the end of s1. If no null wide character was copied
-     from s2, then s1[s1max-m+n] is set to a null wide character.
-13   All elements following the terminating null wide character (if any) written by
-     wcsncat_s in the array of s1max wide characters pointed to by s1 take unspecified
-     values when wcsncat_s returns.430)
-     Returns
-14   The wcsncat_s function returns zero431) if there was no runtime-constraint violation.
-     Otherwise, a nonzero value is returned.
-15   EXAMPLE 1 The wcsncat_s function can be used to copy a wide string without the danger that the
-     result will not be null terminated or that wide characters will be written past the end of the destination
-     array.
-              #define __STDC_WANT_LIB_EXT1__ 1
-              #include <wchar.h>
-              /* ... */
-              wchar_t s1[100] = L"good";
-              wchar_t s2[6] = L"hello";
-              wchar_t s3[6] = L"hello";
-              wchar_t s4[7] = L"abc";
-              wchar_t s5[1000] = L"bye";
-              int r1, r2, r3, r4;
-              r1 = wcsncat_s(s1, 100, s5, 1000);
-              r2 = wcsncat_s(s2, 6, L"", 1);
-              r3 = wcsncat_s(s3, 6, L"X", 2);
-              r4 = wcsncat_s(s4, 7, L"defghijklmn", 3);
-     After the first call r1 will have the value zero and s1 will be the wide character sequence goodbye\0.
-     After the second call r2 will have the value zero and s2 will be the wide character sequence hello\0.
-     After the third call r3 will have a nonzero value and s3 will be the wide character sequence \0.
-     After the fourth call r4 will have the value zero and s4 will be the wide character sequence abcdef\0.
-
-
-
-
-     430) This allows an implementation to append wide characters from s2 to s1 while simultaneously
-          checking if any of those wide characters are null. Such an approach might write a wide character to
-          every element of s1 before discovering that the first element should be set to the null wide character.
-     431) A zero return value implies that all of the requested wide characters from the wide string pointed to by
-          s2 were appended to the wide string pointed to by s1 and that the result in s1 is null terminated.
-
-[page 639] (Contents)
-
-    K.3.9.2.3 Wide string search functions
-    K.3.9.2.3.1 The wcstok_s function
-    Synopsis
-1          #define __STDC_WANT_LIB_EXT1__ 1
-           #include <wchar.h>
-           wchar_t *wcstok_s(wchar_t * restrict s1,
-                rsize_t * restrict s1max,
-                const wchar_t * restrict s2,
-                wchar_t ** restrict ptr);
-    Runtime-constraints
-2   None of s1max, s2, or ptr shall be a null pointer. If s1 is a null pointer, then *ptr
-    shall not be a null pointer. The value of *s1max shall not be greater than RSIZE_MAX.
-    The end of the token found shall occur within the first *s1max wide characters of s1 for
-    the first call, and shall occur within the first *s1max wide characters of where searching
-    resumes on subsequent calls.
-3   If there is a runtime-constraint violation, the wcstok_s function does not indirect
-    through the s1 or s2 pointers, and does not store a value in the object pointed to by ptr.
-    Description
-4   A sequence of calls to the wcstok_s function breaks the wide string pointed to by s1
-    into a sequence of tokens, each of which is delimited by a wide character from the wide
-    string pointed to by s2. The fourth argument points to a caller-provided wchar_t
-    pointer into which the wcstok_s function stores information necessary for it to
-    continue scanning the same wide string.
-5   The first call in a sequence has a non-null first argument and s1max points to an object
-    whose value is the number of elements in the wide character array pointed to by the first
-    argument. The first call stores an initial value in the object pointed to by ptr and
-    updates the value pointed to by s1max to reflect the number of elements that remain in
-    relation to ptr. Subsequent calls in the sequence have a null first argument and the
-    objects pointed to by s1max and ptr are required to have the values stored by the
-    previous call in the sequence, which are then updated. The separator wide string pointed
-    to by s2 may be different from call to call.
-6   The first call in the sequence searches the wide string pointed to by s1 for the first wide
-    character that is not contained in the current separator wide string pointed to by s2. If no
-    such wide character is found, then there are no tokens in the wide string pointed to by s1
-    and the wcstok_s function returns a null pointer. If such a wide character is found, it is
-    the start of the first token.
-
-
-[page 640] (Contents)
-
-7    The wcstok_s function then searches from there for the first wide character in s1 that
-     is contained in the current separator wide string. If no such wide character is found, the
-     current token extends to the end of the wide string pointed to by s1, and subsequent
-     searches in the same wide string for a token return a null pointer. If such a wide character
-     is found, it is overwritten by a null wide character, which terminates the current token.
-8    In all cases, the wcstok_s function stores sufficient information in the pointer pointed
-     to by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
-     value for ptr, shall start searching just past the element overwritten by a null wide
-     character (if any).
-     Returns
-9    The wcstok_s function returns a pointer to the first wide character of a token, or a null
-     pointer if there is no token or there is a runtime-constraint violation.
-10   EXAMPLE
-             #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             static wchar_t str1[] = L"?a???b,,,#c";
-             static wchar_t str2[] = L"\t \t";
-             wchar_t *t, *ptr1, *ptr2;
-             rsize_t max1 = wcslen(str1)+1;
-             rsize_t max2 = wcslen(str2)+1;
-             t   =   wcstok_s(str1,   &max1,   "?", &ptr1);        //   t   points to the token "a"
-             t   =   wcstok_s(NULL,   &max1,   ",", &ptr1);        //   t   points to the token "??b"
-             t   =   wcstok_s(str2,   &max2,   " \t", &ptr2);      //   t   is a null pointer
-             t   =   wcstok_s(NULL,   &max1,   "#,", &ptr1);       //   t   points to the token "c"
-             t   =   wcstok_s(NULL,   &max1,   "?", &ptr1);        //   t   is a null pointer
-
-     K.3.9.2.4 Miscellaneous functions
-     K.3.9.2.4.1 The wcsnlen_s function
-     Synopsis
-1            #define __STDC_WANT_LIB_EXT1__ 1
-             #include <wchar.h>
-             size_t wcsnlen_s(const wchar_t *s, size_t maxsize);
-     Description
-2    The wcsnlen_s function computes the length of the wide string pointed to by s.
-     Returns
-3    If s is a null pointer,432) then the wcsnlen_s function returns zero.
-4    Otherwise, the wcsnlen_s function returns the number of wide characters that precede
-     the terminating null wide character. If there is no null wide character in the first
-     maxsize wide characters of s then wcsnlen_s returns maxsize. At most the first
-
-[page 641] (Contents)
-
-    maxsize wide characters of s shall be accessed by wcsnlen_s.
-    K.3.9.3 Extended multibyte/wide character conversion utilities
-    K.3.9.3.1 Restartable multibyte/wide character conversion functions
-1   Unlike wcrtomb, wcrtomb_s does not permit the ps parameter (the pointer to the
-    conversion state) to be a null pointer.
-    K.3.9.3.1.1 The wcrtomb_s function
-    Synopsis
-2           #include <wchar.h>
-            errno_t wcrtomb_s(size_t * restrict retval,
-                 char * restrict s, rsize_t smax,
-                 wchar_t wc, mbstate_t * restrict ps);
-    Runtime-constraints
-3   Neither retval nor ps shall be a null pointer. If s is not a null pointer, then smax
-    shall not equal zero and shall not be greater than RSIZE_MAX. If s is not a null pointer,
-    then smax shall be not be less than the number of bytes to be stored in the array pointed
-    to by s. If s is a null pointer, then smax shall equal zero.
-4   If there is a runtime-constraint violation, then wcrtomb_s does the following. If s is
-    not a null pointer and smax is greater than zero and not greater than RSIZE_MAX, then
-    wcrtomb_s sets s[0] to the null character. If retval is not a null pointer, then
-    wcrtomb_s sets *retval to (size_t)(-1).
-    Description
-5   If s is a null pointer, the wcrtomb_s function is equivalent to the call
-                    wcrtomb_s(&retval, buf, sizeof buf, L'\0', ps)
-    where retval and buf are internal variables of the appropriate types, and the size of
-    buf is greater than MB_CUR_MAX.
-6   If s is not a null pointer, the wcrtomb_s function determines the number of bytes
-    needed to represent the multibyte character that corresponds to the wide character given
-    by wc (including any shift sequences), and stores the multibyte character representation
-    in the array whose first element is pointed to by s. At most MB_CUR_MAX bytes are
-    stored. If wc is a null wide character, a null byte is stored, preceded by any shift
-    sequence needed to restore the initial shift state; the resulting state described is the initial
-    conversion state.
-
-    432) Note that the wcsnlen_s function has no runtime-constraints. This lack of runtime-constraints
-         along with the values returned for a null pointer or an unterminated wide string argument make
-         wcsnlen_s useful in algorithms that gracefully handle such exceptional data.
-
-[page 642] (Contents)
-
-7   If wc does not correspond to a valid multibyte character, an encoding error occurs: the
-    wcrtomb_s function stores the value (size_t)(-1) into *retval and the
-    conversion state is unspecified. Otherwise, the wcrtomb_s function stores into
-    *retval the number of bytes (including any shift sequences) stored in the array pointed
-    to by s.
-    Returns
-8   The wcrtomb_s function returns zero if no runtime-constraint violation and no
-    encoding error occurred. Otherwise, a nonzero value is returned.
-    K.3.9.3.2 Restartable multibyte/wide string conversion functions
-1   Unlike mbsrtowcs and wcsrtombs, mbsrtowcs_s and wcsrtombs_s do not
-    permit the ps parameter (the pointer to the conversion state) to be a null pointer.
-    K.3.9.3.2.1 The mbsrtowcs_s function
-    Synopsis
-2           #include <wchar.h>
-            errno_t mbsrtowcs_s(size_t * restrict retval,
-                 wchar_t * restrict dst, rsize_t dstmax,
-                 const char ** restrict src, rsize_t len,
-                 mbstate_t * restrict ps);
-    Runtime-constraints
-3   None of retval, src, *src, or ps shall be null pointers. If dst is not a null pointer,
-    then neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null
-    pointer, then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall
-    not equal zero. If dst is not a null pointer and len is not less than dstmax, then a null
-    character shall occur within the first dstmax multibyte characters of the array pointed to
-    by *src.
-4   If there is a runtime-constraint violation, then mbsrtowcs_s does the following. If
-    retval is not a null pointer, then mbsrtowcs_s sets *retval to (size_t)(-1).
-    If dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
-    then mbsrtowcs_s sets dst[0] to the null wide character.
-    Description
-5   The mbsrtowcs_s function converts a sequence of multibyte characters that begins in
-    the conversion state described by the object pointed to by ps, from the array indirectly
-    pointed to by src into a sequence of corresponding wide characters. If dst is not a null
-    pointer, the converted characters are stored into the array pointed to by dst. Conversion
-    continues up to and including a terminating null character, which is also stored.
-    Conversion stops earlier in two cases: when a sequence of bytes is encountered that does
-    not form a valid multibyte character, or (if dst is not a null pointer) when len wide
-[page 643] (Contents)
-
-     characters have been stored into the array pointed to by dst.433) If dst is not a null
-     pointer and no null wide character was stored into the array pointed to by dst, then
-     dst[len] is set to the null wide character. Each conversion takes place as if by a call
-     to the mbrtowc function.
-6    If dst is not a null pointer, the pointer object pointed to by src is assigned either a null
-     pointer (if conversion stopped due to reaching a terminating null character) or the address
-     just past the last multibyte character converted (if any). If conversion stopped due to
-     reaching a terminating null character and if dst is not a null pointer, the resulting state
-     described is the initial conversion state.
-7    Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
-     sequence of bytes that do not form a valid multibyte character, an encoding error occurs:
-     the mbsrtowcs_s function stores the value (size_t)(-1) into *retval and the
-     conversion state is unspecified. Otherwise, the mbsrtowcs_s function stores into
-     *retval the number of multibyte characters successfully converted, not including the
-     terminating null character (if any).
-8    All elements following the terminating null wide character (if any) written by
-     mbsrtowcs_s in the array of dstmax wide characters pointed to by dst take
-     unspecified values when mbsrtowcs_s returns.434)
-9    If copying takes place between objects that overlap, the objects take on unspecified
-     values.
-     Returns
-10   The mbsrtowcs_s function returns zero if no runtime-constraint violation and no
-     encoding error occurred. Otherwise, a nonzero value is returned.
-     K.3.9.3.2.2 The wcsrtombs_s function
-     Synopsis
-11            #include <wchar.h>
-              errno_t wcsrtombs_s(size_t * restrict retval,
-                   char * restrict dst, rsize_t dstmax,
-                   const wchar_t ** restrict src, rsize_t len,
-                   mbstate_t * restrict ps);
-
-
-
-
-     433) Thus, the value of len is ignored if dst is a null pointer.
-     434) This allows an implementation to attempt converting the multibyte string before discovering a
-          terminating null character did not occur where required.
-
-[page 644] (Contents)
-
-     Runtime-constraints
-12   None of retval, src, *src, or ps shall be null pointers. If dst is not a null pointer,
-     then neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null
-     pointer, then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall
-     not equal zero. If dst is not a null pointer and len is not less than dstmax, then the
-     conversion shall have been stopped (see below) because a terminating null wide character
-     was reached or because an encoding error occurred.
-13   If there is a runtime-constraint violation, then wcsrtombs_s does the following. If
-     retval is not a null pointer, then wcsrtombs_s sets *retval to (size_t)(-1).
-     If dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
-     then wcsrtombs_s sets dst[0] to the null character.
-     Description
-14   The wcsrtombs_s function converts a sequence of wide characters from the array
-     indirectly pointed to by src into a sequence of corresponding multibyte characters that
-     begins in the conversion state described by the object pointed to by ps. If dst is not a
-     null pointer, the converted characters are then stored into the array pointed to by dst.
-     Conversion continues up to and including a terminating null wide character, which is also
-     stored. Conversion stops earlier in two cases:
-     -- when a wide character is reached that does not correspond to a valid multibyte
-       character;
-     -- (if dst is not a null pointer) when the next multibyte character would exceed the
-         limit of n total bytes to be stored into the array pointed to by dst. If the wide
-         character being converted is the null wide character, then n is the lesser of len or
-         dstmax. Otherwise, n is the lesser of len or dstmax-1.
-     If the conversion stops without converting a null wide character and dst is not a null
-     pointer, then a null character is stored into the array pointed to by dst immediately
-     following any multibyte characters already stored. Each conversion takes place as if by a
-     call to the wcrtomb function.435)
-15   If dst is not a null pointer, the pointer object pointed to by src is assigned either a null
-     pointer (if conversion stopped due to reaching a terminating null wide character) or the
-     address just past the last wide character converted (if any). If conversion stopped due to
-     reaching a terminating null wide character, the resulting state described is the initial
-     conversion state.
-
-
-     435) If conversion stops because a terminating null wide character has been reached, the bytes stored
-          include those necessary to reach the initial shift state immediately before the null byte. However, if
-          the conversion stops before a terminating null wide character has been reached, the result will be null
-          terminated, but might not end in the initial shift state.
-
-[page 645] (Contents)
-
-16   Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
-     wide character that does not correspond to a valid multibyte character, an encoding error
-     occurs: the wcsrtombs_s function stores the value (size_t)(-1) into *retval
-     and the conversion state is unspecified. Otherwise, the wcsrtombs_s function stores
-     into *retval the number of bytes in the resulting multibyte character sequence, not
-     including the terminating null character (if any).
-17   All elements following the terminating null character (if any) written by wcsrtombs_s
-     in the array of dstmax elements pointed to by dst take unspecified values when
-     wcsrtombs_s returns.436)
-18   If copying takes place between objects that overlap, the objects take on unspecified
-     values.
-     Returns
-19   The wcsrtombs_s function returns zero if no runtime-constraint violation and no
-     encoding error occurred. Otherwise, a nonzero value is returned.
-
-
-
-
-     436) When len is not less than dstmax, the implementation might fill the array before discovering a
-          runtime-constraint violation.
-
-[page 646] (Contents)
-
-                                                Annex L
-                                               (normative)
-                                            Analyzability
-    L.1 Scope
-1   This annex specifies optional behavior that can aid in the analyzability of C programs.
-2   An implementation that defines __STDC_ANALYZABLE__ shall conform to the
-    specifications in this annex.437)
-    L.2 Definitions
-    L.2.1
-1   out-of-bounds store
-    an (attempted) access (3.1) that, at run time, for a given computational state, would
-    modify (or, for an object declared volatile, fetch) one or more bytes that lie outside
-    the bounds permitted by this Standard.
-    L.2.2
-1   bounded undefined behavior
-    undefined behavior (3.4.3) that does not perform an out-of-bounds store.
-2   NOTE 1    The behavior might perform a trap.
-
-3   NOTE 2    Any values produced or stored might be indeterminate values.
-
-    L.2.3
-1   critical undefined behavior
-    undefined behavior that is not bounded undefined behavior.
-2   NOTE     The behavior might perform an out-of-bounds store or perform a trap.
-
-
-
-
-    437) Implementations that do not define __STDC_ANALYZABLE__ are not required to conform to these
-         specifications.
-
-[page 647] (Contents)
-
-    L.3 Requirements
-1   If the program performs a trap (3.19.5), the implementation is permitted to invoke a
-    runtime-constraint handler. Any such semantics are implementation-defined.
-2   All undefined behavior shall be limited to bounded undefined behavior, except for the
-    following which are permitted to result in critical undefined behavior:
-    -- An object is referred to outside of its lifetime (6.2.4).
-    -- An lvalue does not designate an object when evaluated (6.3.2.1).
-    -- A pointer is used to call a function whose type is not compatible with the referenced
-      type (6.3.2.3).
-    -- The operand of the unary * operator has an invalid value (6.5.3.2).
-    -- Addition or subtraction of a pointer into, or just beyond, an array object and an
-      integer type produces a result that points just beyond the array object and is used as
-      the operand of a unary * operator that is evaluated (6.5.6).
-    -- An argument to a library function has an invalid value or a type not expected by a
-      function with variable number of arguments (7.1.4).
-    -- The value of a pointer that refers to space deallocated by a call to the free or realloc
-      function is used (7.22.3).
-    -- A string or wide string utility function is instructed to access an array beyond the end
-      of an object (7.23.1, 7.28.4).
-
-
-
-
-[page 648] (Contents)
-
-
-                                   Bibliography
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-        published in The C Programming Language by Brian W. Kernighan and Dennis
-        M. Ritchie, Prentice-Hall, Inc., (1978). Copyright owned by AT&T.
-  2.    1984 /usr/group Standard by the /usr/group Standards Committee, Santa Clara,
-        California, USA, November 1984.
-  3.    ANSI X3/TR-1-82 (1982), American National Dictionary for Information
-        Processing Systems, Information Processing Systems Technical Report.
-  4.    ANSI/IEEE 754-1985, American National Standard for Binary Floating-Point
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-  5.    ANSI/IEEE 854-1988, American National Standard for Radix-Independent
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-
-
-[page 649] (Contents)
-
- 20.   ISO/IEC 9945-2:1993, Information technology -- Portable Operating System
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- 23.   ISO/IEC 10646-1/COR1:1996,         Technical       Corrigendum       1      to
-       ISO/IEC 10646-1:1993.
- 24.   ISO/IEC 10646-1/COR2:1998,         Technical       Corrigendum       2      to
-       ISO/IEC 10646-1:1993.
- 25.   ISO/IEC 10646-1/AMD1:1996, Amendment 1 to ISO/IEC 10646-1:1993
-       Transformation Format for 16 planes of group 00 (UTF-16).
- 26.   ISO/IEC 10646-1/AMD2:1996, Amendment 2 to ISO/IEC 10646-1:1993 UCS
-       Transformation Format 8 (UTF-8).
- 27.   ISO/IEC 10646-1/AMD3:1996, Amendment 3 to ISO/IEC 10646-1:1993.
- 28.   ISO/IEC 10646-1/AMD4:1996, Amendment 4 to ISO/IEC 10646-1:1993.
- 29.   ISO/IEC 10646-1/AMD5:1998, Amendment 5 to ISO/IEC 10646-1:1993 Hangul
-       syllables.
- 30.   ISO/IEC 10646-1/AMD6:1997,       Amendment     6   to   ISO/IEC 10646-1:1993
-       Tibetan.
- 31.   ISO/IEC 10646-1/AMD7:1997, Amendment 7 to ISO/IEC 10646-1:1993 33
-       additional characters.
- 32.   ISO/IEC 10646-1/AMD8:1997, Amendment 8 to ISO/IEC 10646-1:1993.
- 33.   ISO/IEC 10646-1/AMD9:1997,       Amendment     9   to   ISO/IEC 10646-1:1993
-       Identifiers for characters.
- 34.   ISO/IEC 10646-1/AMD10:1998, Amendment 10 to ISO/IEC 10646-1:1993
-       Ethiopic.
- 35.   ISO/IEC 10646-1/AMD11:1998, Amendment 11 to ISO/IEC 10646-1:1993
-       Unified Canadian Aboriginal Syllabics.
- 36.   ISO/IEC 10646-1/AMD12:1998, Amendment 12 to ISO/IEC 10646-1:1993
-       Cherokee.
- 37.   ISO/IEC 10967-1:1994, Information technology -- Language independent
-       arithmetic -- Part 1: Integer and floating point arithmetic.
-
-
-[page 650] (Contents)
-
- 38.    ISO/IEC TR 19769:2004, Information technology -- Programming languages,
-        their environments and system software interfaces -- Extensions for the
-        programming language C to support new character data types.
- 39.    ISO/IEC TR 24731-1:2007, Information technology -- Programming languages,
-        their environments and system software interfaces -- Extensions to the C library
-        -- Part 1: Bounds-checking interfaces.
-
-
-
-
-[page 651] (Contents)
-
-
-
-[page 652] (Contents)
-
-
-Index
-[^ x ^], 3.20                                                    , (comma operator), 5.1.2.4, 6.5.17
-                                                               , (comma punctuator), 6.5.2, 6.7, 6.7.2.1, 6.7.2.2,
-[_ x _], 3.21                                                         6.7.2.3, 6.7.9
-! (logical negation operator), 6.5.3.3                         - (subtraction operator), 6.2.6.2, 6.5.6, F.3, G.5.2
-!= (inequality operator), 6.5.9                                - (unary minus operator), 6.5.3.3, F.3
-# operator, 6.10.3.2                                           -- (postfix decrement operator), 6.3.2.1, 6.5.2.4
-# preprocessing directive, 6.10.7                              -- (prefix decrement operator), 6.3.2.1, 6.5.3.1
-# punctuator, 6.10                                             -= (subtraction assignment operator), 6.5.16.2
-## operator, 6.10.3.3                                          -> (structure/union pointer operator), 6.5.2.3
-#define preprocessing directive, 6.10.3                        . (structure/union member operator), 6.3.2.1,
-#elif preprocessing directive, 6.10.1                               6.5.2.3
-#else preprocessing directive, 6.10.1                          . punctuator, 6.7.9
-#endif preprocessing directive, 6.10.1                         ... (ellipsis punctuator), 6.5.2.2, 6.7.6.3, 6.10.3
-#error preprocessing directive, 4, 6.10.5                      / (division operator), 6.2.6.2, 6.5.5, F.3, G.5.1
-#if preprocessing directive, 5.2.4.2.1, 5.2.4.2.2,             /* */ (comment delimiters), 6.4.9
-     6.10.1, 7.1.4                                             // (comment delimiter), 6.4.9
-#ifdef preprocessing directive, 6.10.1                         /= (division assignment operator), 6.5.16.2
-#ifndef preprocessing directive, 6.10.1                        : (colon punctuator), 6.7.2.1
-#include preprocessing directive, 5.1.1.2,                     :> (alternative spelling of ]), 6.4.6
-     6.10.2                                                    ; (semicolon punctuator), 6.7, 6.7.2.1, 6.8.3,
-#line preprocessing directive, 6.10.4                               6.8.5, 6.8.6
-#pragma preprocessing directive, 6.10.6                        < (less-than operator), 6.5.8
-#undef preprocessing directive, 6.10.3.5, 7.1.3,               <% (alternative spelling of {), 6.4.6
-     7.1.4                                                     <: (alternative spelling of [), 6.4.6
-% (remainder operator), 6.2.6.2, 6.5.5                         << (left-shift operator), 6.2.6.2, 6.5.7
-%: (alternative spelling of #), 6.4.6                          <<= (left-shift assignment operator), 6.5.16.2
-%:%: (alternative spelling of ##), 6.4.6                       <= (less-than-or-equal-to operator), 6.5.8
-%= (remainder assignment operator), 6.5.16.2                   <assert.h> header, 7.2
-%> (alternative spelling of }), 6.4.6                          <complex.h> header, 5.2.4.2.2, 6.10.8.3, 7.1.2,
-& (address operator), 6.3.2.1, 6.5.3.2                              7.3, 7.24, 7.30.1, G.6, J.5.17
-& (bitwise AND operator), 6.2.6.2, 6.5.10                      <ctype.h> header, 7.4, 7.30.2
-&& (logical AND operator), 5.1.2.4, 6.5.13                     <errno.h> header, 7.5, 7.30.3, K.3.2
-&= (bitwise AND assignment operator), 6.5.16.2                 <fenv.h> header, 5.1.2.3, 5.2.4.2.2, 7.6, 7.12, F,
-' ' (space character), 5.1.1.2, 5.2.1, 6.4, 7.4.1.3,                H
-     7.4.1.10, 7.29.2.1.3                                      <float.h> header, 4, 5.2.4.2.2, 7.7, 7.22.1.3,
-( ) (cast operator), 6.5.4                                          7.28.4.1.1
-( ) (function-call operator), 6.5.2.2                          <inttypes.h> header, 7.8, 7.30.4
-( ) (parentheses punctuator), 6.7.6.3, 6.8.4, 6.8.5            <iso646.h> header, 4, 7.9
-( ){ } (compound-literal operator), 6.5.2.5                    <limits.h> header, 4, 5.2.4.2.1, 6.2.5, 7.10
-* (asterisk punctuator), 6.7.6.1, 6.7.6.2                      <locale.h> header, 7.11, 7.30.5
-* (indirection operator), 6.5.2.1, 6.5.3.2                     <math.h> header, 5.2.4.2.2, 6.5, 7.12, 7.24, F,
-* (multiplication operator), 6.2.6.2, 6.5.5, F.3,                   F.10, J.5.17
-     G.5.1                                                     <setjmp.h> header, 7.13
-*= (multiplication assignment operator), 6.5.16.2              <signal.h> header, 7.14, 7.30.6
-+ (addition operator), 6.2.6.2, 6.5.2.1, 6.5.3.2,              <stdalign.h> header, 4, 7.15
-     6.5.6, F.3, G.5.2                                         <stdarg.h> header, 4, 6.7.6.3, 7.16
-+ (unary plus operator), 6.5.3.3                               <stdatomic.h> header, 6.10.8.3, 7.1.2, 7.17
-++ (postfix increment operator), 6.3.2.1, 6.5.2.4               <stdbool.h> header, 4, 7.18, 7.30.7, H
-++ (prefix increment operator), 6.3.2.1, 6.5.3.1                <stddef.h> header, 4, 6.3.2.1, 6.3.2.3, 6.4.4.4,
-+= (addition assignment operator), 6.5.16.2
-[page 653] (Contents)
-
-     6.4.5, 6.5.3.4, 6.5.6, 7.19, K.3.3                      \x hexadecimal digits (hexadecimal-character
-<stdint.h> header, 4, 5.2.4.2, 6.10.1, 7.8,                       escape sequence), 6.4.4.4
-     7.20, 7.30.8, K.3.3, K.3.4                              ^ (bitwise exclusive OR operator), 6.2.6.2, 6.5.11
-<stdio.h> header, 5.2.4.2.2, 7.21, 7.30.9, F,                ^= (bitwise exclusive OR assignment operator),
-     K.3.5                                                        6.5.16.2
-<stdlib.h> header, 5.2.4.2.2, 7.22, 7.30.10, F,              __alignas_is_defined macro, 7.15
-     K.3.1.4, K.3.6                                          __bool_true_false_are_defined
-<string.h> header, 7.23, 7.30.11, K.3.7                           macro, 7.18
-<tgmath.h> header, 7.24, G.7                                 __cplusplus macro, 6.10.8
-<threads.h> header, 6.10.8.3, 7.1.2, 7.25                    __DATE__ macro, 6.10.8.1
-<time.h> header, 7.26, K.3.8                                 __FILE__ macro, 6.10.8.1, 7.2.1.1
-<uchar.h> header, 6.4.4.4, 6.4.5, 7.27                       __func__ identifier, 6.4.2.2, 7.2.1.1
-<wchar.h> header, 5.2.4.2.2, 7.21.1, 7.28,                   __LINE__ macro, 6.10.8.1, 7.2.1.1
-     7.30.12, F, K.3.9                                       __STDC_, 6.11.9
-<wctype.h> header, 7.29, 7.30.13                             __STDC__ macro, 6.10.8.1
-= (equal-sign punctuator), 6.7, 6.7.2.2, 6.7.9               __STDC_ANALYZABLE__ macro, 6.10.8.3, L.1
-= (simple assignment operator), 6.5.16.1                     __STDC_HOSTED__ macro, 6.10.8.1
-== (equality operator), 6.5.9                                __STDC_IEC_559__ macro, 6.10.8.3, F.1
-> (greater-than operator), 6.5.8                             __STDC_IEC_559_COMPLEX__ macro,
->= (greater-than-or-equal-to operator), 6.5.8                     6.10.8.3, G.1
->> (right-shift operator), 6.2.6.2, 6.5.7                    __STDC_ISO_10646__ macro, 6.10.8.2
->>= (right-shift assignment operator), 6.5.16.2              __STDC_LIB_EXT1__ macro, 6.10.8.3, K.2
-? : (conditional operator), 5.1.2.4, 6.5.15                  __STDC_MB_MIGHT_NEQ_WC__ macro,
-?? (trigraph sequences), 5.2.1.1                                  6.10.8.2, 7.19
-[ ] (array subscript operator), 6.5.2.1, 6.5.3.2             __STDC_NO_COMPLEX__ macro, 6.10.8.3,
-[ ] (brackets punctuator), 6.7.6.2, 6.7.9                         7.3.1
-\ (backslash character), 5.1.1.2, 5.2.1, 6.4.4.4             __STDC_NO_THREADS__ macro, 6.10.8.3,
-\ (escape character), 6.4.4.4                                     7.17.1, 7.25.1
-\" (double-quote escape sequence), 6.4.4.4,                  __STDC_NO_VLA__ macro, 6.10.8.3
-     6.4.5, 6.10.9                                           __STDC_UTF_16__ macro, 6.10.8.2
-\\ (backslash escape sequence), 6.4.4.4, 6.10.9              __STDC_UTF_32__ macro, 6.10.8.2
-\' (single-quote escape sequence), 6.4.4.4, 6.4.5            __STDC_VERSION__ macro, 6.10.8.1
-\0 (null character), 5.2.1, 6.4.4.4, 6.4.5                   __STDC_WANT_LIB_EXT1__ macro, K.3.1.1
-  padding of binary stream, 7.21.2                           __TIME__ macro, 6.10.8.1
-\? (question-mark escape sequence), 6.4.4.4                  __VA_ARGS__ identifier, 6.10.3, 6.10.3.1
-\a (alert escape sequence), 5.2.2, 6.4.4.4                   _Alignas, 6.7.5
-\b (backspace escape sequence), 5.2.2, 6.4.4.4               _Atomic type qualifier, 6.7.2, 6.7.3
-\f (form-feed escape sequence), 5.2.2, 6.4.4.4,              _Atomic-qualified type, 6.2.5, 6.2.6.1, 6.5.2.3,
-     7.4.1.10                                                     6.5.2.4, 6.5.16.2, 6.7.2, 6.7.3
-\n (new-line escape sequence), 5.2.2, 6.4.4.4,               _Bool type, 6.2.5, 6.3.1.1, 6.3.1.2, 6.7.2, 7.17.1,
-     7.4.1.10                                                     F.4
-\octal digits (octal-character escape sequence),             _Bool type conversions, 6.3.1.2
-     6.4.4.4                                                 _Complex types, 6.2.5, 6.7.2, 7.3.1, G
-\r (carriage-return escape sequence), 5.2.2,                 _Complex_I macro, 7.3.1
-     6.4.4.4, 7.4.1.10                                       _Exit function, 7.22.4.5, 7.22.4.7
-\t (horizontal-tab escape sequence), 5.2.2,                  _Imaginary keyword, G.2
-     6.4.4.4, 7.4.1.3, 7.4.1.10, 7.29.2.1.3                  _Imaginary types, 7.3.1, G
-\U (universal character names), 6.4.3                        _Imaginary_I macro, 7.3.1, G.6
-\u (universal character names), 6.4.3                        _IOFBF macro, 7.21.1, 7.21.5.5, 7.21.5.6
-\v (vertical-tab escape sequence), 5.2.2, 6.4.4.4,           _IOLBF macro, 7.21.1, 7.21.5.6
-     7.4.1.10                                                _IONBF macro, 7.21.1, 7.21.5.5, 7.21.5.6
-
-[page 654] (Contents)
-
-_Noreturn, 6.7.4                                             alignment specifier, 6.7.5
-_Pragma operator, 5.1.1.2, 6.10.9                            alignof operator, 6.5.3, 6.5.3.4
-_Static_assert, 6.7.10, 7.2                                  allocated storage, order and contiguity, 7.22.3
-_Thread_local storage-class specifier, 6.2.4,                 and macro, 7.9
-     6.7.1                                                   AND operators
-{ } (braces punctuator), 6.7.2.2, 6.7.2.3, 6.7.9,               bitwise (&), 6.2.6.2, 6.5.10
-     6.8.2                                                      bitwise assignment (&=), 6.5.16.2
-{ } (compound-literal operator), 6.5.2.5                        logical (&&), 5.1.2.4, 6.5.13
-| (bitwise inclusive OR operator), 6.2.6.2, 6.5.12           and_eq macro, 7.9
-|= (bitwise inclusive OR assignment operator),               anonymous structure, 6.7.2.1
-     6.5.16.2                                                anonymous union, 6.7.2.1
-|| (logical OR operator), 5.1.2.4, 6.5.14                    ANSI/IEEE 754, F.1
-~ (bitwise complement operator), 6.2.6.2, 6.5.3.3            ANSI/IEEE 854, F.1
-                                                             argc (main function parameter), 5.1.2.2.1
-abort function, 7.2.1.1, 7.14.1.1, 7.21.3,                   argument, 3.3
-      7.22.4.1, 7.25.3.6, K.3.6.1.2                             array, 6.9.1
-abort_handler_s function, K.3.6.1.2                             default promotions, 6.5.2.2
-abs function, 7.22.6.1                                          function, 6.5.2.2, 6.9.1
-absolute-value functions                                        macro, substitution, 6.10.3.1
-   complex, 7.3.8, G.6.4                                     argument, complex, 7.3.9.1
-   integer, 7.8.2.1, 7.22.6.1                                argv (main function parameter), 5.1.2.2.1
-   real, 7.12.7, F.10.4                                      arithmetic constant expression, 6.6
-abstract declarator, 6.7.7                                   arithmetic conversions, usual, see usual arithmetic
-abstract machine, 5.1.2.3                                          conversions
-access, 3.1, 6.7.3, L.2.1                                    arithmetic operators
-accuracy, see floating-point accuracy                            additive, 6.2.6.2, 6.5.6, G.5.2
-acos functions, 7.12.4.1, F.10.1.1                              bitwise, 6.2.6.2, 6.5.3.3, 6.5.10, 6.5.11, 6.5.12
-acos type-generic macro, 7.24                                   increment and decrement, 6.5.2.4, 6.5.3.1
-acosh functions, 7.12.5.1, F.10.2.1                             multiplicative, 6.2.6.2, 6.5.5, G.5.1
-acosh type-generic macro, 7.24                                  shift, 6.2.6.2, 6.5.7
-acquire fence, 7.17.4                                           unary, 6.5.3.3
-acquire operation, 5.1.2.4                                   arithmetic types, 6.2.5
-active position, 5.2.2                                       arithmetic, pointer, 6.5.6
-actual argument, 3.3                                         array
-actual parameter (deprecated), 3.3                              argument, 6.9.1
-addition assignment operator (+=), 6.5.16.2                     declarator, 6.7.6.2
-addition operator (+), 6.2.6.2, 6.5.2.1, 6.5.3.2,               initialization, 6.7.9
-      6.5.6, F.3, G.5.2                                         multidimensional, 6.5.2.1
-additive expressions, 6.5.6, G.5.2                              parameter, 6.9.1
-address constant, 6.6                                           storage order, 6.5.2.1
-address operator (&), 6.3.2.1, 6.5.3.2                          subscript operator ([ ]), 6.5.2.1, 6.5.3.2
-address-free, 7.17.5                                            subscripting, 6.5.2.1
-aggregate initialization, 6.7.9                                 type, 6.2.5
-aggregate types, 6.2.5                                          type conversion, 6.3.2.1
-alert escape sequence (\a), 5.2.2, 6.4.4.4                      variable length, 6.7.6, 6.7.6.2, 6.10.8.3
-aliasing, 6.5                                                arrow operator (->), 6.5.2.3
-alignas macro, 7.15                                          as-if rule, 5.1.2.3
-aligned_alloc function, 7.22.3, 7.22.3.1                     ASCII code set, 5.2.1.1
-alignment, 3.2, 6.2.8, 7.22.3.1                              asctime function, 7.26.3.1
-   pointer, 6.2.5, 6.3.2.3                                   asctime_s function, K.3.8.2, K.3.8.2.1
-   structure/union member, 6.7.2.1                           asin functions, 7.12.4.2, F.10.1.2
-
-[page 655] (Contents)
-
-asin type-generic macro, 7.24, G.7                       atomic_is_lock_free generic function,
-asinh functions, 7.12.5.2, F.10.2.2                          7.17.5.1
-asinh type-generic macro, 7.24, G.7                      ATOMIC_LLONG_LOCK_FREE macro, 7.17.1
-asm keyword, J.5.10                                      atomic_load generic functions, 7.17.7.2
-assert macro, 7.2.1.1                                    ATOMIC_LONG_LOCK_FREE macro, 7.17.1
-assert.h header, 7.2                                     ATOMIC_SHORT_LOCK_FREE macro, 7.17.1
-assignment                                               atomic_signal_fence function, 7.17.4.2
-   compound, 6.5.16.2                                    atomic_store generic functions, 7.17.7.1
-   conversion, 6.5.16.1                                  atomic_thread_fence function, 7.17.4.1
-   expression, 6.5.16                                    ATOMIC_VAR_INIT macro, 7.17.2.1
-   operators, 6.3.2.1, 6.5.16                            ATOMIC_WCHAR_T_LOCK_FREE macro, 7.17.1
-   simple, 6.5.16.1                                      atomics header, 7.17
-associativity of operators, 6.5                          auto storage-class specifier, 6.7.1, 6.9
-asterisk punctuator (*), 6.7.6.1, 6.7.6.2                automatic storage duration, 5.2.3, 6.2.4
-at_quick_exit function, 7.22.4.2, 7.22.4.3,
-     7.22.4.4, 7.22.4.5, 7.22.4.7                        backslash character (\), 5.1.1.2, 5.2.1, 6.4.4.4
-atan functions, 7.12.4.3, F.10.1.3                       backslash escape sequence (\\), 6.4.4.4, 6.10.9
-atan type-generic macro, 7.24, G.7                       backspace escape sequence (\b), 5.2.2, 6.4.4.4
-atan2 functions, 7.12.4.4, F.10.1.4                      basic character set, 3.6, 3.7.2, 5.2.1
-atan2 type-generic macro, 7.24                           basic types, 6.2.5
-atanh functions, 7.12.5.3, F.10.2.3                      behavior, 3.4
-atanh type-generic macro, 7.24, G.7                      binary streams, 7.21.2, 7.21.7.10, 7.21.9.2,
-atexit function, 7.22.4.2, 7.22.4.3, 7.22.4.4,                 7.21.9.4
-     7.22.4.5, 7.22.4.7, J.5.13                          bit, 3.5
-atof function, 7.22.1, 7.22.1.1                             high order, 3.6
-atoi function, 7.22.1, 7.22.1.2                             low order, 3.6
-atol function, 7.22.1, 7.22.1.2                          bit-field, 6.7.2.1
-atoll function, 7.22.1, 7.22.1.2                         bitand macro, 7.9
-atomic lock-free macros, 7.17.1, 7.17.5                  bitor macro, 7.9
-atomic operations, 5.1.2.4                               bitwise operators, 6.5
-atomic types, 5.1.2.3, 6.10.8.3, 7.17.6                     AND, 6.2.6.2, 6.5.10
-atomic_address type, 7.17.1, 7.17.6                         AND assignment (&=), 6.5.16.2
-ATOMIC_ADDRESS_LOCK_FREE macro, 7.17.1                      complement (~), 6.2.6.2, 6.5.3.3
-atomic_bool type, 7.17.1, 7.17.6                            exclusive OR, 6.2.6.2, 6.5.11
-ATOMIC_CHAR16_T_LOCK_FREE macro,                            exclusive OR assignment (^=), 6.5.16.2
-     7.17.1                                                 inclusive OR, 6.2.6.2, 6.5.12
-ATOMIC_CHAR32_T_LOCK_FREE macro,                            inclusive OR assignment (|=), 6.5.16.2
-     7.17.1                                                 shift, 6.2.6.2, 6.5.7
-ATOMIC_CHAR_LOCK_FREE macro, 7.17.1                      blank character, 7.4.1.3
-atomic_compare_exchange generic                          block, 6.8, 6.8.2, 6.8.4, 6.8.5
-     functions, 7.17.7.4                                 block scope, 6.2.1
-atomic_exchange generic functions, 7.17.7.3              block structure, 6.2.1
-atomic_fetch and modify generic functions,               bold type convention, 6.1
-     7.17.7.5                                            bool macro, 7.18
-atomic_flag type, 7.17.1, 7.17.8                         boolean type, 6.3.1.2
-atomic_flag_clear functions, 7.17.8.2                    boolean type conversion, 6.3.1.1, 6.3.1.2
-ATOMIC_FLAG_INIT macro, 7.17.1, 7.17.8                   bounded undefined behavior, L.2.2
-atomic_flag_test_and_set functions,                      braces punctuator ({ }), 6.7.2.2, 6.7.2.3, 6.7.9,
-     7.17.8.1                                                  6.8.2
-atomic_init generic function, 7.17.2.2                   brackets operator ([ ]), 6.5.2.1, 6.5.3.2
-ATOMIC_INT_LOCK_FREE macro, 7.17.1                       brackets punctuator ([ ]), 6.7.6.2, 6.7.9
-
-[page 656] (Contents)
-
-branch cuts, 7.3.3                                                type-generic macro for, 7.24
-break statement, 6.8.6.3                                       ccosh functions, 7.3.6.4, G.6.2.4
-broken-down time, 7.26.1, 7.26.2.3, 7.26.3,                       type-generic macro for, 7.24
-     7.26.3.1, 7.26.3.3, 7.26.3.4, 7.26.3.5,                   ceil functions, 7.12.9.1, F.10.6.1
-     K.3.8.2.1, K.3.8.2.3, K.3.8.2.4                           ceil type-generic macro, 7.24
-bsearch function, 7.22.5, 7.22.5.1                             cerf function, 7.30.1
-bsearch_s function, K.3.6.3, K.3.6.3.1                         cerfc function, 7.30.1
-btowc function, 7.28.6.1.1                                     cexp functions, 7.3.7.1, G.6.3.1
-BUFSIZ macro, 7.21.1, 7.21.2, 7.21.5.5                            type-generic macro for, 7.24
-byte, 3.6, 6.5.3.4                                             cexp2 function, 7.30.1
-byte input/output functions, 7.21.1                            cexpm1 function, 7.30.1
-byte-oriented stream, 7.21.2                                   char type, 6.2.5, 6.3.1.1, 6.7.2, K.3.5.3.2,
-                                                                     K.3.9.1.2
-C program, 5.1.1.1                                             char type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4,
-c16rtomb function, 7.27.1.2                                          6.3.1.8
-c32rtomb function, 7.27.1.4                                    char16_t type, 6.4.4.4, 6.4.5, 6.10.8.2, 7.27
-cabs functions, 7.3.8.1, G.6                                   char32_t type, 6.4.4.4, 6.4.5, 6.10.8.2, 7.27
-  type-generic macro for, 7.24                                 CHAR_BIT macro, 5.2.4.2.1, 6.7.2.1
-cacos functions, 7.3.5.1, G.6.1.1                              CHAR_MAX macro, 5.2.4.2.1, 7.11.2.1
-  type-generic macro for, 7.24                                 CHAR_MIN macro, 5.2.4.2.1
-cacosh functions, 7.3.6.1, G.6.2.1                             character, 3.7, 3.7.1
-  type-generic macro for, 7.24                                 character array initialization, 6.7.9
-calendar time, 7.26.1, 7.26.2.2, 7.26.2.3, 7.26.2.4,           character case mapping functions, 7.4.2
-      7.26.3.2, 7.26.3.3, 7.26.3.4, K.3.8.2.2,                    wide character, 7.29.3.1
-      K.3.8.2.3, K.3.8.2.4                                           extensible, 7.29.3.2
-call by value, 6.5.2.2                                         character classification functions, 7.4.1
-call_once function, 7.25.1, 7.25.2.1                              wide character, 7.29.2.1
-calloc function, 7.22.3, 7.22.3.2                                    extensible, 7.29.2.2
-carg functions, 7.3.9.1, G.6                                   character constant, 5.1.1.2, 5.2.1, 6.4.4.4
-carg type-generic macro, 7.24, G.7                             character display semantics, 5.2.2
-carriage-return escape sequence (\r), 5.2.2,                   character handling header, 7.4, 7.11.1.1
-      6.4.4.4, 7.4.1.10                                        character input/output functions, 7.21.7, K.3.5.4
-carries a dependency, 5.1.2.4                                     wide character, 7.28.3
-case label, 6.8.1, 6.8.4.2                                     character sets, 5.2.1
-case mapping functions                                         character string literal, see string literal
-  character, 7.4.2                                             character type conversion, 6.3.1.1
-  wide character, 7.29.3.1                                     character types, 6.2.5, 6.7.9
-      extensible, 7.29.3.2                                     cimag functions, 7.3.9.2, 7.3.9.5, G.6
-casin functions, 7.3.5.2, G.6                                  cimag type-generic macro, 7.24, G.7
-  type-generic macro for, 7.24                                 cis function, G.6
-casinh functions, 7.3.6.2, G.6.2.2                             classification functions
-  type-generic macro for, 7.24                                    character, 7.4.1
-cast expression, 6.5.4                                            floating-point, 7.12.3
-cast operator (( )), 6.5.4                                        wide character, 7.29.2.1
-catan functions, 7.3.5.3, G.6                                        extensible, 7.29.2.2
-  type-generic macro for, 7.24                                 clearerr function, 7.21.10.1
-catanh functions, 7.3.6.3, G.6.2.3                             clgamma function, 7.30.1
-  type-generic macro for, 7.24                                 clock function, 7.26.2.1
-cbrt functions, 7.12.7.1, F.10.4.1                             clock_t type, 7.26.1, 7.26.2.1
-cbrt type-generic macro, 7.24                                  CLOCKS_PER_SEC macro, 7.26.1, 7.26.2.1
-ccos functions, 7.3.5.4, G.6                                   clog functions, 7.3.7.2, G.6.3.2
-
-[page 657] (Contents)
-
-  type-generic macro for, 7.24                                  string, 7.23.3, K.3.7.2
-clog10 function, 7.30.1                                         wide string, 7.28.4.3, K.3.9.2.2
-clog1p function, 7.30.1                                       concatenation, preprocessing, see preprocessing
-clog2 function, 7.30.1                                             concatenation
-CMPLX macros, 7.3.9.3                                         conceptual models, 5.1
-cnd_broadcast function, 7.25.3.1, 7.25.3.5,                   conditional features, 4, 6.2.5, 6.7.6.2, 6.10.8.3,
-     7.25.3.6                                                      7.1.2, F.1, G.1, K.2, L.1
-cnd_destroy function, 7.25.3.2                                conditional inclusion, 6.10.1
-cnd_init function, 7.25.3.3                                   conditional operator (? :), 5.1.2.4, 6.5.15
-cnd_signal function, 7.25.3.4, 7.25.3.5,                      conflict, 5.1.2.4
-     7.25.3.6                                                 conformance, 4
-cnd_t type, 7.25.1                                            conj functions, 7.3.9.4, G.6
-cnd_timedwait function, 7.25.3.5                              conj type-generic macro, 7.24
-cnd_wait function, 7.25.3.3, 7.25.3.6                         const type qualifier, 6.7.3
-collating sequences, 5.2.1                                    const-qualified type, 6.2.5, 6.3.2.1, 6.7.3
-colon punctuator (:), 6.7.2.1                                 constant expression, 6.6, F.8.4
-comma operator (,), 5.1.2.4, 6.5.17                           constants, 6.4.4
-comma punctuator (,), 6.5.2, 6.7, 6.7.2.1, 6.7.2.2,             as primary expression, 6.5.1
-     6.7.2.3, 6.7.9                                             character, 6.4.4.4
-command processor, 7.22.4.8                                     enumeration, 6.2.1, 6.4.4.3
-comment delimiters (/* */ and //), 6.4.9                        floating, 6.4.4.2
-comments, 5.1.1.2, 6.4, 6.4.9                                   hexadecimal, 6.4.4.1
-common extensions, J.5                                          integer, 6.4.4.1
-common initial sequence, 6.5.2.3                                octal, 6.4.4.1
-common real type, 6.3.1.8                                     constraint, 3.8, 4
-common warnings, I                                            constraint_handler_t type, K.3.6
-comparison functions, 7.22.5, 7.22.5.1, 7.22.5.2,             consume operation, 5.1.2.4
-     K.3.6.3, K.3.6.3.1, K.3.6.3.2                            content of structure/union/enumeration, 6.7.2.3
-  string, 7.23.4                                              contiguity of allocated storage, 7.22.3
-  wide string, 7.28.4.4                                       continue statement, 6.8.6.2
-comparison macros, 7.12.14                                    contracted expression, 6.5, 7.12.2, F.7
-comparison, pointer, 6.5.8                                    control character, 5.2.1, 7.4
-compatible type, 6.2.7, 6.7.2, 6.7.3, 6.7.6                   control wide character, 7.29.2
-compl macro, 7.9                                              conversion, 6.3
-complement operator (~), 6.2.6.2, 6.5.3.3                       arithmetic operands, 6.3.1
-complete type, 6.2.5                                            array argument, 6.9.1
-complex macro, 7.3.1                                            array parameter, 6.9.1
-complex numbers, 6.2.5, G                                       arrays, 6.3.2.1
-complex type conversion, 6.3.1.6, 6.3.1.7                       boolean, 6.3.1.2
-complex type domain, 6.2.5                                      boolean, characters, and integers, 6.3.1.1
-complex types, 6.2.5, 6.7.2, 6.10.8.3, G                        by assignment, 6.5.16.1
-complex.h header, 5.2.4.2.2, 6.10.8.3, 7.1.2,                   by return statement, 6.8.6.4
-     7.3, 7.24, 7.30.1, G.6, J.5.17                             complex types, 6.3.1.6
-compliance, see conformance                                     explicit, 6.3
-components of time, 7.26.1, K.3.8.1                             function, 6.3.2.1
-composite type, 6.2.7                                           function argument, 6.5.2.2, 6.9.1
-compound assignment, 6.5.16.2                                   function designators, 6.3.2.1
-compound literals, 6.5.2.5                                      function parameter, 6.9.1
-compound statement, 6.8.2                                       imaginary, G.4.1
-compound-literal operator (( ){ }), 6.5.2.5                     imaginary and complex, G.4.3
-concatenation functions                                         implicit, 6.3
-
-[page 658] (Contents)
-
-   lvalues, 6.3.2.1                                             csinh functions, 7.3.6.5, G.6.2.5
-   pointer, 6.3.2.1, 6.3.2.3                                      type-generic macro for, 7.24
-   real and complex, 6.3.1.7                                    csqrt functions, 7.3.8.3, G.6.4.2
-   real and imaginary, G.4.2                                      type-generic macro for, 7.24
-   real floating and integer, 6.3.1.4, F.3, F.4                  ctan functions, 7.3.5.6, G.6
-   real floating types, 6.3.1.5, F.3                               type-generic macro for, 7.24
-   signed and unsigned integers, 6.3.1.3                        ctanh functions, 7.3.6.6, G.6.2.6
-   usual arithmetic, see usual arithmetic                         type-generic macro for, 7.24
-         conversions                                            ctgamma function, 7.30.1
-   void type, 6.3.2.2                                           ctime function, 7.26.3.2
-conversion functions                                            ctime_s function, K.3.8.2, K.3.8.2.2
-   multibyte/wide character, 7.22.7, K.3.6.4                    ctype.h header, 7.4, 7.30.2
-      extended, 7.28.6, K.3.9.3                                 current object, 6.7.9
-      restartable, 7.27.1, 7.28.6.3, K.3.9.3.1                  CX_LIMITED_RANGE pragma, 6.10.6, 7.3.4
-   multibyte/wide string, 7.22.8, K.3.6.5
-      restartable, 7.28.6.4, K.3.9.3.2                          data race, 5.1.2.4, 7.1.4, 7.22.2.1, 7.22.4.6,
-   numeric, 7.8.2.3, 7.22.1                                          7.23.5.8, 7.23.6.2, 7.26.3, 7.27.1, 7.28.6.3,
-      wide string, 7.8.2.4, 7.28.4.1                                 7.28.6.4
-   single byte/wide character, 7.28.6.1                         data stream, see streams
-   time, 7.26.3, K.3.8.2                                        date and time header, 7.26, K.3.8
-      wide character, 7.28.5                                    Daylight Saving Time, 7.26.1
-conversion specifier, 7.21.6.1, 7.21.6.2, 7.28.2.1,              DBL_DECIMAL_DIG macro, 5.2.4.2.2
-      7.28.2.2                                                  DBL_DIG macro, 5.2.4.2.2
-conversion state, 7.22.7, 7.27.1, 7.27.1.1,                     DBL_EPSILON macro, 5.2.4.2.2
-      7.27.1.2, 7.27.1.3, 7.27.1.4, 7.28.6,                     DBL_HAS_SUBNORM macro, 5.2.4.2.2
-      7.28.6.2.1, 7.28.6.3, 7.28.6.3.2, 7.28.6.3.3,             DBL_MANT_DIG macro, 5.2.4.2.2
-      7.28.6.4, 7.28.6.4.1, 7.28.6.4.2, K.3.6.4,                DBL_MAX macro, 5.2.4.2.2
-      K.3.9.3.1, K.3.9.3.1.1, K.3.9.3.2, K.3.9.3.2.1,           DBL_MAX_10_EXP macro, 5.2.4.2.2
-      K.3.9.3.2.2                                               DBL_MAX_EXP macro, 5.2.4.2.2
-conversion state functions, 7.28.6.2                            DBL_MIN macro, 5.2.4.2.2
-copying functions                                               DBL_MIN_10_EXP macro, 5.2.4.2.2
-   string, 7.23.2, K.3.7.1                                      DBL_MIN_EXP macro, 5.2.4.2.2
-   wide string, 7.28.4.2, K.3.9.2.1                             DBL_TRUE_MIN macro, 5.2.4.2.2
-copysign functions, 7.3.9.5, 7.12.11.1, F.3,                    decimal constant, 6.4.4.1
-      F.10.8.1                                                  decimal digit, 5.2.1
-copysign type-generic macro, 7.24                               decimal-point character, 7.1.1, 7.11.2.1
-correctly rounded result, 3.9                                   DECIMAL_DIG macro, 5.2.4.2.2, 7.21.6.1,
-corresponding real type, 6.2.5                                       7.22.1.3, 7.28.2.1, 7.28.4.1.1, F.5
-cos functions, 7.12.4.5, F.10.1.5                               declaration specifiers, 6.7
-cos type-generic macro, 7.24, G.7                               declarations, 6.7
-cosh functions, 7.12.5.4, F.10.2.4                                function, 6.7.6.3
-cosh type-generic macro, 7.24, G.7                                pointer, 6.7.6.1
-cpow functions, 7.3.8.2, G.6.4.1                                  structure/union, 6.7.2.1
-   type-generic macro for, 7.24                                   typedef, 6.7.8
-cproj functions, 7.3.9.5, G.6                                   declarator, 6.7.6
-cproj type-generic macro, 7.24                                    abstract, 6.7.7
-creal functions, 7.3.9.6, G.6                                   declarator type derivation, 6.2.5, 6.7.6
-creal type-generic macro, 7.24, G.7                             decrement operators, see arithmetic operators,
-critical undefined behavior, L.2.3                                    increment and decrement
-csin functions, 7.3.5.5, G.6                                    default argument promotions, 6.5.2.2
-   type-generic macro for, 7.24                                 default initialization, 6.7.9
-
-[page 659] (Contents)
-
-default label, 6.8.1, 6.8.4.2                                  elif preprocessing directive, 6.10.1
-define preprocessing directive, 6.10.3                         ellipsis punctuator (...), 6.5.2.2, 6.7.6.3, 6.10.3
-defined operator, 6.10.1, 6.10.8                               else preprocessing directive, 6.10.1
-definition, 6.7                                                 else statement, 6.8.4.1
-   function, 6.9.1                                             empty statement, 6.8.3
-dependency-ordered before, 5.1.2.4                             encoding error, 7.21.3, 7.27.1.1, 7.27.1.2,
-derived declarator types, 6.2.5                                      7.27.1.3, 7.27.1.4, 7.28.3.1, 7.28.3.3,
-derived types, 6.2.5                                                 7.28.6.3.2, 7.28.6.3.3, 7.28.6.4.1, 7.28.6.4.2,
-designated initializer, 6.7.9                                        K.3.6.5.1, K.3.6.5.2, K.3.9.3.1.1, K.3.9.3.2.1,
-destringizing, 6.10.9                                                K.3.9.3.2.2
-device input/output, 5.1.2.3                                   end-of-file, 7.28.1
-diagnostic message, 3.10, 5.1.1.3                              end-of-file indicator, 7.21.1, 7.21.5.3, 7.21.7.1,
-diagnostics, 5.1.1.3                                                 7.21.7.5, 7.21.7.6, 7.21.7.10, 7.21.9.2,
-diagnostics header, 7.2                                              7.21.9.3, 7.21.10.1, 7.21.10.2, 7.28.3.1,
-difftime function, 7.26.2.2                                          7.28.3.10
-digit, 5.2.1, 7.4                                              end-of-file macro, see EOF macro
-digraphs, 6.4.6                                                end-of-line indicator, 5.2.1
-direct input/output functions, 7.21.8                          endif preprocessing directive, 6.10.1
-display device, 5.2.2                                          enum type, 6.2.5, 6.7.2, 6.7.2.2
-div function, 7.22.6.2                                         enumerated type, 6.2.5
-div_t type, 7.22                                               enumeration, 6.2.5, 6.7.2.2
-division assignment operator (/=), 6.5.16.2                    enumeration constant, 6.2.1, 6.4.4.3
-division operator (/), 6.2.6.2, 6.5.5, F.3, G.5.1              enumeration content, 6.7.2.3
-do statement, 6.8.5.2                                          enumeration members, 6.7.2.2
-documentation of implementation, 4                             enumeration specifiers, 6.7.2.2
-domain error, 7.12.1, 7.12.4.1, 7.12.4.2, 7.12.4.4,            enumeration tag, 6.2.3, 6.7.2.3
-      7.12.5.1, 7.12.5.3, 7.12.6.5, 7.12.6.7,                  enumerator, 6.7.2.2
-      7.12.6.8, 7.12.6.9, 7.12.6.10, 7.12.6.11,                environment, 5
-      7.12.7.4, 7.12.7.5, 7.12.8.4, 7.12.9.5,                  environment functions, 7.22.4, K.3.6.2
-      7.12.9.7, 7.12.10.1, 7.12.10.2, 7.12.10.3                environment list, 7.22.4.6, K.3.6.2.1
-dot operator (.), 6.5.2.3                                      environmental considerations, 5.2
-double _Complex type, 6.2.5                                    environmental limits, 5.2.4, 7.13.1.1, 7.21.2,
-double _Complex type conversion, 6.3.1.6,                            7.21.3, 7.21.4.4, 7.21.6.1, 7.22.2.1, 7.22.4.2,
-      6.3.1.7, 6.3.1.8                                               7.22.4.3, 7.28.2.1, K.3.5.1.2
-double _Imaginary type, G.2                                    EOF macro, 7.4, 7.21.1, 7.21.5.1, 7.21.5.2,
-double type, 6.2.5, 6.4.4.2, 6.7.2, 7.21.6.2,                        7.21.6.2, 7.21.6.7, 7.21.6.9, 7.21.6.11,
-      7.28.2.2, F.2                                                  7.21.6.14, 7.21.7.1, 7.21.7.3, 7.21.7.4,
-double type conversion, 6.3.1.4, 6.3.1.5, 6.3.1.7,                   7.21.7.5, 7.21.7.6, 7.21.7.8, 7.21.7.9,
-      6.3.1.8                                                        7.21.7.10, 7.28.1, 7.28.2.2, 7.28.2.4,
-double-precision arithmetic, 5.1.2.3                                 7.28.2.6, 7.28.2.8, 7.28.2.10, 7.28.2.12,
-double-quote escape sequence (\"), 6.4.4.4,                          7.28.3.4, 7.28.6.1.1, 7.28.6.1.2, K.3.5.3.7,
-      6.4.5, 6.10.9                                                  K.3.5.3.9, K.3.5.3.11, K.3.5.3.14, K.3.9.1.2,
-double_t type, 7.12, J.5.6                                           K.3.9.1.5, K.3.9.1.7, K.3.9.1.10, K.3.9.1.12,
-                                                                     K.3.9.1.14
-EDOM macro, 7.5, 7.12.1, see also domain error                 equal-sign punctuator (=), 6.7, 6.7.2.2, 6.7.9
-effective type, 6.5                                            equal-to operator, see equality operator
-EILSEQ macro, 7.5, 7.21.3, 7.27.1.1, 7.27.1.2,                 equality expressions, 6.5.9
-     7.27.1.3, 7.27.1.4, 7.28.3.1, 7.28.3.3,                   equality operator (==), 6.5.9
-     7.28.6.3.2, 7.28.6.3.3, 7.28.6.4.1, 7.28.6.4.2,           ERANGE macro, 7.5, 7.8.2.3, 7.8.2.4, 7.12.1,
-     see also encoding error                                         7.22.1.3, 7.22.1.4, 7.28.4.1.1, 7.28.4.1.2, see
-element type, 6.2.5                                                  also range error, pole error
-
-[page 660] (Contents)
-
-erf functions, 7.12.8.1, F.10.5.1                               exp type-generic macro, 7.24
-erf type-generic macro, 7.24                                    exp2 functions, 7.12.6.2, F.10.3.2
-erfc functions, 7.12.8.2, F.10.5.2                              exp2 type-generic macro, 7.24
-erfc type-generic macro, 7.24                                   explicit conversion, 6.3
-errno macro, 7.1.3, 7.3.2, 7.5, 7.8.2.3, 7.8.2.4,               expm1 functions, 7.12.6.3, F.10.3.3
-      7.12.1, 7.14.1.1, 7.21.3, 7.21.9.3, 7.21.10.4,            expm1 type-generic macro, 7.24
-      7.22.1, 7.22.1.3, 7.22.1.4, 7.23.6.2, 7.27.1.1,           exponent part, 6.4.4.2
-      7.27.1.2, 7.27.1.3, 7.27.1.4, 7.28.3.1,                   exponential functions
-      7.28.3.3, 7.28.4.1.1, 7.28.4.1.2, 7.28.6.3.2,               complex, 7.3.7, G.6.3
-      7.28.6.3.3, 7.28.6.4.1, 7.28.6.4.2, J.5.17,                 real, 7.12.6, F.10.3
-      K.3.1.3, K.3.7.4.2                                        expression, 6.5
-errno.h header, 7.5, 7.30.3, K.3.2                                assignment, 6.5.16
-errno_t type, K.3.2, K.3.5, K.3.6, K.3.6.1.1,                     cast, 6.5.4
-      K.3.7, K.3.8, K.3.9                                         constant, 6.6
-error                                                             evaluation, 5.1.2.3
-   domain, see domain error                                       full, 6.8
-   encoding, see encoding error                                   order of evaluation, see order of evaluation
-   pole, see pole error                                           parenthesized, 6.5.1
-   range, see range error                                         primary, 6.5.1
-error conditions, 7.12.1                                          unary, 6.5.3
-error functions, 7.12.8, F.10.5                                 expression statement, 6.8.3
-error indicator, 7.21.1, 7.21.5.3, 7.21.7.1,                    extended alignment, 6.2.8
-      7.21.7.3, 7.21.7.5, 7.21.7.6, 7.21.7.7,                   extended character set, 3.7.2, 5.2.1, 5.2.1.2
-      7.21.7.8, 7.21.9.2, 7.21.10.1, 7.21.10.3,                 extended characters, 5.2.1
-      7.28.3.1, 7.28.3.3                                        extended integer types, 6.2.5, 6.3.1.1, 6.4.4.1,
-error preprocessing directive, 4, 6.10.5                             7.20
-error-handling functions, 7.21.10, 7.23.6.2,                    extended multibyte/wide character conversion
-      K.3.7.4.2, K.3.7.4.3                                           utilities, 7.28.6, K.3.9.3
-escape character (\), 6.4.4.4                                   extensible wide character case mapping functions,
-escape sequences, 5.2.1, 5.2.2, 6.4.4.4, 6.11.4                      7.29.3.2
-evaluation format, 5.2.4.2.2, 6.4.4.2, 7.12                     extensible wide character classification functions,
-evaluation method, 5.2.4.2.2, 6.5, F.8.5                             7.29.2.2
-evaluation of expression, 5.1.2.3                               extern storage-class specifier, 6.2.2, 6.7.1
-evaluation order, see order of evaluation                       external definition, 6.9
-exceptional condition, 6.5                                      external identifiers, underscore, 7.1.3
-excess precision, 5.2.4.2.2, 6.3.1.5, 6.3.1.8,                  external linkage, 6.2.2
-      6.8.6.4                                                   external name, 6.4.2.1
-excess range, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, 6.8.6.4              external object definitions, 6.9.2
-exclusive OR operators
-   bitwise (^), 6.2.6.2, 6.5.11                                 fabs functions, 7.12.7.2, F.3, F.10.4.2
-   bitwise assignment (^=), 6.5.16.2                            fabs type-generic macro, 7.24, G.7
-executable program, 5.1.1.1                                     false macro, 7.18
-execution character set, 5.2.1                                  fclose function, 7.21.5.1
-execution environment, 5, 5.1.2, see also                       fdim functions, 7.12.12.1, F.10.9.1
-      environmental limits                                      fdim type-generic macro, 7.24
-execution sequence, 5.1.2.3, 6.8                                FE_ALL_EXCEPT macro, 7.6
-exit function, 5.1.2.2.3, 7.21.3, 7.22, 7.22.4.4,               FE_DFL_ENV macro, 7.6
-      7.22.4.5, 7.22.4.7                                        FE_DIVBYZERO macro, 7.6, 7.12, F.3
-EXIT_FAILURE macro, 7.22, 7.22.4.4                              FE_DOWNWARD macro, 7.6, F.3
-EXIT_SUCCESS macro, 7.22, 7.22.4.4                              FE_INEXACT macro, 7.6, F.3
-exp functions, 7.12.6.1, F.10.3.1                               FE_INVALID macro, 7.6, 7.12, F.3
-
-[page 661] (Contents)
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-FE_OVERFLOW macro, 7.6, 7.12, F.3                            float _Complex type, 6.2.5
-FE_TONEAREST macro, 7.6, F.3                                 float _Complex type conversion, 6.3.1.6,
-FE_TOWARDZERO macro, 7.6, F.3                                     6.3.1.7, 6.3.1.8
-FE_UNDERFLOW macro, 7.6, F.3                                 float _Imaginary type, G.2
-FE_UPWARD macro, 7.6, F.3                                    float type, 6.2.5, 6.4.4.2, 6.7.2, F.2
-feclearexcept function, 7.6.2, 7.6.2.1, F.3                  float type conversion, 6.3.1.4, 6.3.1.5, 6.3.1.7,
-fegetenv function, 7.6.4.1, 7.6.4.3, 7.6.4.4, F.3                 6.3.1.8
-fegetexceptflag function, 7.6.2, 7.6.2.2, F.3                float.h header, 4, 5.2.4.2.2, 7.7, 7.22.1.3,
-fegetround function, 7.6, 7.6.3.1, F.3                            7.28.4.1.1
-feholdexcept function, 7.6.4.2, 7.6.4.3,                     float_t type, 7.12, J.5.6
-     7.6.4.4, F.3                                            floating constant, 6.4.4.2
-fence, 5.1.2.4                                               floating suffix, f or F, 6.4.4.2
-fences, 7.17.4                                               floating type conversion, 6.3.1.4, 6.3.1.5, 6.3.1.7,
-fenv.h header, 5.1.2.3, 5.2.4.2.2, 7.6, 7.12, F, H                F.3, F.4
-FENV_ACCESS pragma, 6.10.6, 7.6.1, F.8, F.9,                 floating types, 6.2.5, 6.11.1
-     F.10                                                    floating-point accuracy, 5.2.4.2.2, 6.4.4.2, 6.5,
-fenv_t type, 7.6                                                  7.22.1.3, F.5, see also contracted expression
-feof function, 7.21.10.2                                     floating-point arithmetic functions, 7.12, F.10
-feraiseexcept function, 7.6.2, 7.6.2.3, F.3                  floating-point classification functions, 7.12.3
-ferror function, 7.21.10.3                                   floating-point control mode, 7.6, F.8.6
-fesetenv function, 7.6.4.3, F.3                              floating-point environment, 7.6, F.8, F.8.6
-fesetexceptflag function, 7.6.2, 7.6.2.4, F.3                floating-point exception, 7.6, 7.6.2, F.10
-fesetround function, 7.6, 7.6.3.2, F.3                       floating-point number, 5.2.4.2.2, 6.2.5
-fetestexcept function, 7.6.2, 7.6.2.5, F.3                   floating-point rounding mode, 5.2.4.2.2
-feupdateenv function, 7.6.4.2, 7.6.4.4, F.3                  floating-point status flag, 7.6, F.8.6
-fexcept_t type, 7.6, F.3                                     floor functions, 7.12.9.2, F.10.6.2
-fflush function, 7.21.5.2, 7.21.5.3                          floor type-generic macro, 7.24
-fgetc function, 7.21.1, 7.21.3, 7.21.7.1,                    FLT_DECIMAL_DIG macro, 5.2.4.2.2
-     7.21.7.5, 7.21.8.1                                      FLT_DIG macro, 5.2.4.2.2
-fgetpos function, 7.21.2, 7.21.9.1, 7.21.9.3                 FLT_EPSILON macro, 5.2.4.2.2
-fgets function, 7.21.1, 7.21.7.2, K.3.5.4.1                  FLT_EVAL_METHOD macro, 5.2.4.2.2, 6.6, 7.12,
-fgetwc function, 7.21.1, 7.21.3, 7.28.3.1,                        F.10.11
-     7.28.3.6                                                FLT_HAS_SUBNORM macro, 5.2.4.2.2
-fgetws function, 7.21.1, 7.28.3.2                            FLT_MANT_DIG macro, 5.2.4.2.2
-field width, 7.21.6.1, 7.28.2.1                               FLT_MAX macro, 5.2.4.2.2
-file, 7.21.3                                                  FLT_MAX_10_EXP macro, 5.2.4.2.2
-  access functions, 7.21.5, K.3.5.2                          FLT_MAX_EXP macro, 5.2.4.2.2
-  name, 7.21.3                                               FLT_MIN macro, 5.2.4.2.2
-  operations, 7.21.4, K.3.5.1                                FLT_MIN_10_EXP macro, 5.2.4.2.2
-  position indicator, 7.21.1, 7.21.2, 7.21.3,                FLT_MIN_EXP macro, 5.2.4.2.2
-        7.21.5.3, 7.21.7.1, 7.21.7.3, 7.21.7.10,             FLT_RADIX macro, 5.2.4.2.2, 7.21.6.1, 7.22.1.3,
-        7.21.8.1, 7.21.8.2, 7.21.9.1, 7.21.9.2,                   7.28.2.1, 7.28.4.1.1
-        7.21.9.3, 7.21.9.4, 7.21.9.5, 7.28.3.1,              FLT_ROUNDS macro, 5.2.4.2.2, 7.6, F.3
-        7.28.3.3, 7.28.3.10                                  FLT_TRUE_MIN macro, 5.2.4.2.2
-  positioning functions, 7.21.9                              fma functions, 7.12, 7.12.13.1, F.10.10.1
-file scope, 6.2.1, 6.9                                        fma type-generic macro, 7.24
-FILE type, 7.21.1, 7.21.3                                    fmax functions, 7.12.12.2, F.10.9.2
-FILENAME_MAX macro, 7.21.1                                   fmax type-generic macro, 7.24
-flags, 7.21.6.1, 7.28.2.1, see also floating-point             fmin functions, 7.12.12.3, F.10.9.3
-     status flag                                              fmin type-generic macro, 7.24
-flexible array member, 6.7.2.1                                fmod functions, 7.12.10.1, F.10.7.1
-
-[page 662] (Contents)
-
-fmod type-generic macro, 7.24                                 fscanf_s function, K.3.5.3.2, K.3.5.3.4,
-fopen function, 7.21.5.3, 7.21.5.4, K.3.5.2.1                       K.3.5.3.7, K.3.5.3.9
-FOPEN_MAX macro, 7.21.1, 7.21.3, 7.21.4.3,                    fseek function, 7.21.1, 7.21.5.3, 7.21.7.10,
-     K.3.5.1.1                                                      7.21.9.2, 7.21.9.4, 7.21.9.5, 7.28.3.10
-fopen_s function, K.3.5.1.1, K.3.5.2.1,                       fsetpos function, 7.21.2, 7.21.5.3, 7.21.7.10,
-     K.3.5.2.2                                                      7.21.9.1, 7.21.9.3, 7.28.3.10
-for statement, 6.8.5, 6.8.5.3                                 ftell function, 7.21.9.2, 7.21.9.4
-form-feed character, 5.2.1, 6.4                               full declarator, 6.7.6
-form-feed escape sequence (\f), 5.2.2, 6.4.4.4,               full expression, 6.8
-     7.4.1.10                                                 fully buffered stream, 7.21.3
-formal argument (deprecated), 3.16                            function
-formal parameter, 3.16                                           argument, 6.5.2.2, 6.9.1
-formatted input/output functions, 7.11.1.1, 7.21.6,              body, 6.9.1
-     K.3.5.3                                                     call, 6.5.2.2
-   wide character, 7.28.2, K.3.9.1                                  library, 7.1.4
-fortran keyword, J.5.9                                           declarator, 6.7.6.3, 6.11.6
-forward reference, 3.11                                          definition, 6.7.6.3, 6.9.1, 6.11.7
-FP_CONTRACT pragma, 6.5, 6.10.6, 7.12.2, see                     designator, 6.3.2.1
-     also contracted expression                                  image, 5.2.3
-FP_FAST_FMA macro, 7.12                                          inline, 6.7.4
-FP_FAST_FMAF macro, 7.12                                         library, 5.1.1.1, 7.1.4
-FP_FAST_FMAL macro, 7.12                                         name length, 5.2.4.1, 6.4.2.1, 6.11.3
-FP_ILOGB0 macro, 7.12, 7.12.6.5                                  no-return, 6.7.4
-FP_ILOGBNAN macro, 7.12, 7.12.6.5                                parameter, 5.1.2.2.1, 6.5.2.2, 6.7, 6.9.1
-FP_INFINITE macro, 7.12, F.3                                     prototype, 5.1.2.2.1, 6.2.1, 6.2.7, 6.5.2.2, 6.7,
-FP_NAN macro, 7.12, F.3                                                6.7.6.3, 6.9.1, 6.11.6, 6.11.7, 7.1.2, 7.12
-FP_NORMAL macro, 7.12, F.3                                       prototype scope, 6.2.1, 6.7.6.2
-FP_SUBNORMAL macro, 7.12, F.3                                    recursive call, 6.5.2.2
-FP_ZERO macro, 7.12, F.3                                         return, 6.8.6.4, F.6
-fpclassify macro, 7.12.3.1, F.3                                  scope, 6.2.1
-fpos_t type, 7.21.1, 7.21.2                                      type, 6.2.5
-fprintf function, 7.8.1, 7.21.1, 7.21.6.1,                       type conversion, 6.3.2.1
-     7.21.6.2, 7.21.6.3, 7.21.6.5, 7.21.6.6,                  function specifiers, 6.7.4
-     7.21.6.8, 7.28.2.2, F.3, K.3.5.3.1                       function type, 6.2.5
-fprintf_s function, K.3.5.3.1                                 function-call operator (( )), 6.5.2.2
-fputc function, 5.2.2, 7.21.1, 7.21.3, 7.21.7.3,              function-like macro, 6.10.3
-     7.21.7.7, 7.21.8.2                                       fundamental alignment, 6.2.8
-fputs function, 7.21.1, 7.21.7.4                              future directions
-fputwc function, 7.21.1, 7.21.3, 7.28.3.3,                       language, 6.11
-     7.28.3.8                                                    library, 7.30
-fputws function, 7.21.1, 7.28.3.4                             fwide function, 7.21.2, 7.28.3.5
-fread function, 7.21.1, 7.21.8.1                              fwprintf function, 7.8.1, 7.21.1, 7.21.6.2,
-free function, 7.22.3.3, 7.22.3.5                                   7.28.2.1, 7.28.2.2, 7.28.2.3, 7.28.2.5,
-freestanding execution environment, 4, 5.1.2,                       7.28.2.11, K.3.9.1.1
-     5.1.2.1                                                  fwprintf_s function, K.3.9.1.1
-freopen function, 7.21.2, 7.21.5.4                            fwrite function, 7.21.1, 7.21.8.2
-freopen_s function, K.3.5.2.2                                 fwscanf function, 7.8.1, 7.21.1, 7.28.2.2,
-frexp functions, 7.12.6.4, F.10.3.4                                 7.28.2.4, 7.28.2.6, 7.28.2.12, 7.28.3.10,
-frexp type-generic macro, 7.24                                      K.3.9.1.2
-fscanf function, 7.8.1, 7.21.1, 7.21.6.2,                     fwscanf_s function, K.3.9.1.2, K.3.9.1.5,
-     7.21.6.4, 7.21.6.7, 7.21.6.9, F.3, K.3.5.3.2                   K.3.9.1.7, K.3.9.1.14
-
-[page 663] (Contents)
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-gamma functions, 7.12.8, F.10.5                                name spaces, 6.2.3
-general utilities, 7.22, K.3.6                                 reserved, 6.4.1, 7.1.3, K.3.1.2
-  wide string, 7.28.4, K.3.9.2                                 scope, 6.2.1
-general wide string utilities, 7.28.4, K.3.9.2                 type, 6.2.5
-generic parameters, 7.24                                    identifier list, 6.7.6
-generic selection, 6.5.1.1                                  identifier nondigit, 6.4.2.1
-getc function, 7.21.1, 7.21.7.5, 7.21.7.6                   IEC 559, F.1
-getchar function, 7.21.1, 7.21.7.6                          IEC 60559, 2, 5.1.2.3, 5.2.4.2.2, 6.10.8.3, 7.3.3,
-getenv function, 7.22.4.6                                         7.6, 7.6.4.2, 7.12.1, 7.12.10.2, 7.12.14, F, G,
-getenv_s function, K.3.6.2.1                                      H.1
-gets function, K.3.5.4.1                                    IEEE 754, F.1
-gets_s function, K.3.5.4.1                                  IEEE 854, F.1
-getwc function, 7.21.1, 7.28.3.6, 7.28.3.7                  IEEE floating-point arithmetic standard, see
-getwchar function, 7.21.1, 7.28.3.7                               IEC 60559, ANSI/IEEE 754,
-gmtime function, 7.26.3.3                                         ANSI/IEEE 854
-gmtime_s function, K.3.8.2.3                                if preprocessing directive, 5.2.4.2.1, 5.2.4.2.2,
-goto statement, 6.2.1, 6.8.1, 6.8.6.1                             6.10.1, 7.1.4
-graphic characters, 5.2.1                                   if statement, 6.8.4.1
-greater-than operator (>), 6.5.8                            ifdef preprocessing directive, 6.10.1
-greater-than-or-equal-to operator (>=), 6.5.8               ifndef preprocessing directive, 6.10.1
-                                                            ignore_handler_s function, K.3.6.1.3
-happens before, 5.1.2.4                                     ilogb functions, 7.12, 7.12.6.5, F.10.3.5
-header, 5.1.1.1, 7.1.2, see also standard headers           ilogb type-generic macro, 7.24
-header names, 6.4, 6.4.7, 6.10.2                            imaginary macro, 7.3.1, G.6
-hexadecimal constant, 6.4.4.1                               imaginary numbers, G
-hexadecimal digit, 6.4.4.1, 6.4.4.2, 6.4.4.4                imaginary type domain, G.2
-hexadecimal prefix, 6.4.4.1                                  imaginary types, G
-hexadecimal-character escape sequence                       imaxabs function, 7.8.2.1
-     (\x hexadecimal digits), 6.4.4.4                       imaxdiv function, 7.8, 7.8.2.2
-high-order bit, 3.6                                         imaxdiv_t type, 7.8
-horizontal-tab character, 5.2.1, 6.4                        implementation, 3.12
-horizontal-tab escape sequence (\r), 7.29.2.1.3             implementation limit, 3.13, 4, 5.2.4.2, 6.4.2.1,
-horizontal-tab escape sequence (\t), 5.2.2,                       6.7.6, 6.8.4.2, E, see also environmental
-     6.4.4.4, 7.4.1.3, 7.4.1.10                                   limits
-hosted execution environment, 4, 5.1.2, 5.1.2.2             implementation-defined behavior, 3.4.1, 4, J.3
-HUGE_VAL macro, 7.12, 7.12.1, 7.22.1.3,                     implementation-defined value, 3.19.1
-     7.28.4.1.1, F.10                                       implicit conversion, 6.3
-HUGE_VALF macro, 7.12, 7.12.1, 7.22.1.3,                    implicit initialization, 6.7.9
-     7.28.4.1.1, F.10                                       include preprocessing directive, 5.1.1.2, 6.10.2
-HUGE_VALL macro, 7.12, 7.12.1, 7.22.1.3,                    inclusive OR operators
-     7.28.4.1.1, F.10                                          bitwise (|), 6.2.6.2, 6.5.12
-hyperbolic functions                                           bitwise assignment (|=), 6.5.16.2
-  complex, 7.3.6, G.6.2                                     incomplete type, 6.2.5
-  real, 7.12.5, F.10.2                                      increment operators, see arithmetic operators,
-hypot functions, 7.12.7.3, F.10.4.3                               increment and decrement
-hypot type-generic macro, 7.24                              indeterminate value, 3.19.2
-                                                            indeterminately sequenced, 5.1.2.3, 6.5.2.2,
-I macro, 7.3.1, 7.3.9.5, G.6                                      6.5.2.4, 6.5.16.2, see also sequenced before,
-identifier, 6.4.2.1, 6.5.1                                         unsequenced
-   linkage, see linkage                                     indirection operator (*), 6.5.2.1, 6.5.3.2
-   maximum length, 6.4.2.1                                  inequality operator (!=), 6.5.9
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-[page 664] (Contents)
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-infinitary, 7.12.1                                                    extended, 6.2.5, 6.3.1.1, 6.4.4.1, 7.20
-INFINITY macro, 7.3.9.5, 7.12, F.2.1                              inter-thread happens before, 5.1.2.4
-initial position, 5.2.2                                           interactive device, 5.1.2.3, 7.21.3, 7.21.5.3
-initial shift state, 5.2.1.2                                      internal linkage, 6.2.2
-initialization, 5.1.2, 6.2.4, 6.3.2.1, 6.5.2.5, 6.7.9,            internal name, 6.4.2.1
-      F.8.5                                                       interrupt, 5.2.3
-   in blocks, 6.8                                                 INTMAX_C macro, 7.20.4.2
-initializer, 6.7.9                                                INTMAX_MAX macro, 7.8.2.3, 7.8.2.4, 7.20.2.5
-   permitted form, 6.6                                            INTMAX_MIN macro, 7.8.2.3, 7.8.2.4, 7.20.2.5
-   string literal, 6.3.2.1                                        intmax_t type, 7.20.1.5, 7.21.6.1, 7.21.6.2,
-inline, 6.7.4                                                           7.28.2.1, 7.28.2.2
-inner scope, 6.2.1                                                INTN_C macros, 7.20.4.1
-input failure, 7.28.2.6, 7.28.2.8, 7.28.2.10,                     INTN_MAX macros, 7.20.2.1
-      K.3.5.3.2, K.3.5.3.4, K.3.5.3.7, K.3.5.3.9,                 INTN_MIN macros, 7.20.2.1
-      K.3.5.3.11, K.3.5.3.14, K.3.9.1.2, K.3.9.1.5,               intN_t types, 7.20.1.1
-      K.3.9.1.7, K.3.9.1.10, K.3.9.1.12, K.3.9.1.14               INTPTR_MAX macro, 7.20.2.4
-input/output functions                                            INTPTR_MIN macro, 7.20.2.4
-   character, 7.21.7, K.3.5.4                                     intptr_t type, 7.20.1.4
-   direct, 7.21.8                                                 inttypes.h header, 7.8, 7.30.4
-   formatted, 7.21.6, K.3.5.3                                     isalnum function, 7.4.1.1, 7.4.1.9, 7.4.1.10
-      wide character, 7.28.2, K.3.9.1                             isalpha function, 7.4.1.1, 7.4.1.2
-   wide character, 7.28.3                                         isblank function, 7.4.1.3
-      formatted, 7.28.2, K.3.9.1                                  iscntrl function, 7.4.1.2, 7.4.1.4, 7.4.1.7,
-input/output header, 7.21, K.3.5                                        7.4.1.11
-input/output, device, 5.1.2.3                                     isdigit function, 7.4.1.1, 7.4.1.2, 7.4.1.5,
-int type, 6.2.5, 6.3.1.1, 6.3.1.3, 6.4.4.1, 6.7.2                       7.4.1.7, 7.4.1.11, 7.11.1.1
-int type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4,                   isfinite macro, 7.12.3.2, F.3
-      6.3.1.8                                                     isgraph function, 7.4.1.6
-INT_FASTN_MAX macros, 7.20.2.3                                    isgreater macro, 7.12.14.1, F.3
-INT_FASTN_MIN macros, 7.20.2.3                                    isgreaterequal macro, 7.12.14.2, F.3
-int_fastN_t types, 7.20.1.3                                       isinf macro, 7.12.3.3
-INT_LEASTN_MAX macros, 7.20.2.2                                   isless macro, 7.12.14.3, F.3
-INT_LEASTN_MIN macros, 7.20.2.2                                   islessequal macro, 7.12.14.4, F.3
-int_leastN_t types, 7.20.1.2                                      islessgreater macro, 7.12.14.5, F.3
-INT_MAX macro, 5.2.4.2.1, 7.12, 7.12.6.5                          islower function, 7.4.1.2, 7.4.1.7, 7.4.2.1,
-INT_MIN macro, 5.2.4.2.1, 7.12                                          7.4.2.2
-integer arithmetic functions, 7.8.2.1, 7.8.2.2,                   isnan macro, 7.12.3.4, F.3
-      7.22.6                                                      isnormal macro, 7.12.3.5
-integer character constant, 6.4.4.4                               ISO 31-11, 2, 3
-integer constant, 6.4.4.1                                         ISO 4217, 2, 7.11.2.1
-integer constant expression, 6.3.2.3, 6.6, 6.7.2.1,               ISO 8601, 2, 7.26.3.5
-      6.7.2.2, 6.7.6.2, 6.7.9, 6.7.10, 6.8.4.2, 6.10.1,           ISO/IEC 10646, 2, 6.4.2.1, 6.4.3, 6.10.8.2
-      7.1.4                                                       ISO/IEC 10976-1, H.1
-integer conversion rank, 6.3.1.1                                  ISO/IEC 2382-1, 2, 3
-integer promotions, 5.1.2.3, 5.2.4.2.1, 6.3.1.1,                  ISO/IEC 646, 2, 5.2.1.1
-      6.5.2.2, 6.5.3.3, 6.5.7, 6.8.4.2, 7.20.2, 7.20.3,           ISO/IEC 9945-2, 7.11
-      7.21.6.1, 7.28.2.1                                          ISO/IEC TR 10176, D
-integer suffix, 6.4.4.1                                            iso646.h header, 4, 7.9
-integer type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4,               isprint function, 5.2.2, 7.4.1.8
-      F.3, F.4                                                    ispunct function, 7.4.1.2, 7.4.1.7, 7.4.1.9,
-integer types, 6.2.5, 7.20                                              7.4.1.11
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-[page 665] (Contents)
-
-isspace function, 7.4.1.2, 7.4.1.7, 7.4.1.9,                    Latin alphabet, 5.2.1, 6.4.2.1
-      7.4.1.10, 7.4.1.11, 7.21.6.2, 7.22.1.3,                   LC_ALL macro, 7.11, 7.11.1.1, 7.11.2.1
-      7.22.1.4, 7.28.2.2                                        LC_COLLATE macro, 7.11, 7.11.1.1, 7.23.4.3,
-isunordered macro, 7.12.14.6, F.3                                     7.28.4.4.2
-isupper function, 7.4.1.2, 7.4.1.11, 7.4.2.1,                   LC_CTYPE macro, 7.11, 7.11.1.1, 7.22, 7.22.7,
-      7.4.2.2                                                         7.22.8, 7.28.6, 7.29.1, 7.29.2.2.1, 7.29.2.2.2,
-iswalnum function, 7.29.2.1.1, 7.29.2.1.9,                            7.29.3.2.1, 7.29.3.2.2, K.3.6.4, K.3.6.5
-      7.29.2.1.10, 7.29.2.2.1                                   LC_MONETARY macro, 7.11, 7.11.1.1, 7.11.2.1
-iswalpha function, 7.29.2.1.1, 7.29.2.1.2,                      LC_NUMERIC macro, 7.11, 7.11.1.1, 7.11.2.1
-      7.29.2.2.1                                                LC_TIME macro, 7.11, 7.11.1.1, 7.26.3.5
-iswblank function, 7.29.2.1.3, 7.29.2.2.1                       lconv structure type, 7.11
-iswcntrl function, 7.29.2.1.2, 7.29.2.1.4,                      LDBL_DECIMAL_DIG macro, 5.2.4.2.2
-      7.29.2.1.7, 7.29.2.1.11, 7.29.2.2.1                       LDBL_DIG macro, 5.2.4.2.2
-iswctype function, 7.29.2.2.1, 7.29.2.2.2                       LDBL_EPSILON macro, 5.2.4.2.2
-iswdigit function, 7.29.2.1.1, 7.29.2.1.2,                      LDBL_HAS_SUBNORM macro, 5.2.4.2.2
-      7.29.2.1.5, 7.29.2.1.7, 7.29.2.1.11, 7.29.2.2.1           LDBL_MANT_DIG macro, 5.2.4.2.2
-iswgraph function, 7.29.2.1, 7.29.2.1.6,                        LDBL_MAX macro, 5.2.4.2.2
-      7.29.2.1.10, 7.29.2.2.1                                   LDBL_MAX_10_EXP macro, 5.2.4.2.2
-iswlower function, 7.29.2.1.2, 7.29.2.1.7,                      LDBL_MAX_EXP macro, 5.2.4.2.2
-      7.29.2.2.1, 7.29.3.1.1, 7.29.3.1.2                        LDBL_MIN macro, 5.2.4.2.2
-iswprint function, 7.29.2.1.6, 7.29.2.1.8,                      LDBL_MIN_10_EXP macro, 5.2.4.2.2
-      7.29.2.2.1                                                LDBL_MIN_EXP macro, 5.2.4.2.2
-iswpunct function, 7.29.2.1, 7.29.2.1.2,                        LDBL_TRUE_MIN macro, 5.2.4.2.2
-      7.29.2.1.7, 7.29.2.1.9, 7.29.2.1.10,                      ldexp functions, 7.12.6.6, F.10.3.6
-      7.29.2.1.11, 7.29.2.2.1                                   ldexp type-generic macro, 7.24
-iswspace function, 7.21.6.2, 7.28.2.2,                          ldiv function, 7.22.6.2
-      7.28.4.1.1, 7.28.4.1.2, 7.29.2.1.2, 7.29.2.1.6,           ldiv_t type, 7.22
-      7.29.2.1.7, 7.29.2.1.9, 7.29.2.1.10,                      leading underscore in identifiers, 7.1.3
-      7.29.2.1.11, 7.29.2.2.1                                   left-shift assignment operator (<<=), 6.5.16.2
-iswupper function, 7.29.2.1.2, 7.29.2.1.11,                     left-shift operator (<<), 6.2.6.2, 6.5.7
-      7.29.2.2.1, 7.29.3.1.1, 7.29.3.1.2                        length
-iswxdigit function, 7.29.2.1.12, 7.29.2.2.1                        external name, 5.2.4.1, 6.4.2.1, 6.11.3
-isxdigit function, 7.4.1.12, 7.11.1.1                              function name, 5.2.4.1, 6.4.2.1, 6.11.3
-italic type convention, 3, 6.1                                     identifier, 6.4.2.1
-iteration statements, 6.8.5                                        internal name, 5.2.4.1, 6.4.2.1
-                                                                length function, 7.22.7.1, 7.23.6.3, 7.28.4.6.1,
-jmp_buf type, 7.13                                                    7.28.6.3.1, K.3.7.4.4, K.3.9.2.4.1
-jump statements, 6.8.6                                          length modifier, 7.21.6.1, 7.21.6.2, 7.28.2.1,
-                                                                      7.28.2.2
-keywords, 6.4.1, G.2, J.5.9, J.5.10                             less-than operator (<), 6.5.8
-kill_dependency macro, 5.1.2.4, 7.17.3.1                        less-than-or-equal-to operator (<=), 6.5.8
-known constant size, 6.2.5                                      letter, 5.2.1, 7.4
-                                                                lexical elements, 5.1.1.2, 6.4
-L_tmpnam macro, 7.21.1, 7.21.4.4                                lgamma functions, 7.12.8.3, F.10.5.3
-L_tmpnam_s macro, K.3.5, K.3.5.1.2                              lgamma type-generic macro, 7.24
-label name, 6.2.1, 6.2.3                                        library, 5.1.1.1, 7, K.3
-labeled statement, 6.8.1                                           future directions, 7.30
-labs function, 7.22.6.1                                            summary, B
-language, 6                                                        terms, 7.1.1
-   future directions, 6.11                                         use of functions, 7.1.4
-   syntax summary, A                                            lifetime, 6.2.4
-
-[page 666] (Contents)
-
-limits                                                     long double _Complex type conversion,
-   environmental, see environmental limits                      6.3.1.6, 6.3.1.7, 6.3.1.8
-   implementation, see implementation limits               long double _Imaginary type, G.2
-   numerical, see numerical limits                         long double suffix, l or L, 6.4.4.2
-   translation, see translation limits                     long double type, 6.2.5, 6.4.4.2, 6.7.2,
-limits.h header, 4, 5.2.4.2.1, 6.2.5, 7.10                      7.21.6.1, 7.21.6.2, 7.28.2.1, 7.28.2.2, F.2
-line buffered stream, 7.21.3                               long double type conversion, 6.3.1.4, 6.3.1.5,
-line number, 6.10.4, 6.10.8.1                                   6.3.1.7, 6.3.1.8
-line preprocessing directive, 6.10.4                       long int type, 6.2.5, 6.3.1.1, 6.7.2, 7.21.6.1,
-lines, 5.1.1.2, 7.21.2                                          7.21.6.2, 7.28.2.1, 7.28.2.2
-   preprocessing directive, 6.10                           long int type conversion, 6.3.1.1, 6.3.1.3,
-linkage, 6.2.2, 6.7, 6.7.4, 6.7.6.2, 6.9, 6.9.2,                6.3.1.4, 6.3.1.8
-      6.11.2                                               long integer suffix, l or L, 6.4.4.1
-llabs function, 7.22.6.1                                   long long int type, 6.2.5, 6.3.1.1, 6.7.2,
-lldiv function, 7.22.6.2                                        7.21.6.1, 7.21.6.2, 7.28.2.1, 7.28.2.2
-lldiv_t type, 7.22                                         long long int type conversion, 6.3.1.1,
-LLONG_MAX macro, 5.2.4.2.1, 7.22.1.4,                           6.3.1.3, 6.3.1.4, 6.3.1.8
-      7.28.4.1.2                                           long long integer suffix, ll or LL, 6.4.4.1
-LLONG_MIN macro, 5.2.4.2.1, 7.22.1.4,                      LONG_MAX macro, 5.2.4.2.1, 7.22.1.4, 7.28.4.1.2
-      7.28.4.1.2                                           LONG_MIN macro, 5.2.4.2.1, 7.22.1.4, 7.28.4.1.2
-llrint functions, 7.12.9.5, F.3, F.10.6.5                  longjmp function, 7.13.1.1, 7.13.2.1, 7.22.4.4,
-llrint type-generic macro, 7.24                                 7.22.4.7
-llround functions, 7.12.9.7, F.10.6.7                      loop body, 6.8.5
-llround type-generic macro, 7.24                           low-order bit, 3.6
-local time, 7.26.1                                         lowercase letter, 5.2.1
-locale, 3.4.2                                              lrint functions, 7.12.9.5, F.3, F.10.6.5
-locale-specific behavior, 3.4.2, J.4                        lrint type-generic macro, 7.24
-locale.h header, 7.11, 7.30.5                              lround functions, 7.12.9.7, F.10.6.7
-localeconv function, 7.11.1.1, 7.11.2.1                    lround type-generic macro, 7.24
-localization, 7.11                                         lvalue, 6.3.2.1, 6.5.1, 6.5.2.4, 6.5.3.1, 6.5.16
-localtime function, 7.26.3.4
-localtime_s function, K.3.8.2.4                            macro argument substitution, 6.10.3.1
-log functions, 7.12.6.7, F.10.3.7                          macro definition
-log type-generic macro, 7.24                                 library function, 7.1.4
-log10 functions, 7.12.6.8, F.10.3.8                        macro invocation, 6.10.3
-log10 type-generic macro, 7.24                             macro name, 6.10.3
-log1p functions, 7.12.6.9, F.10.3.9                          length, 5.2.4.1
-log1p type-generic macro, 7.24                               predefined, 6.10.8, 6.11.9
-log2 functions, 7.12.6.10, F.10.3.10                         redefinition, 6.10.3
-log2 type-generic macro, 7.24                                scope, 6.10.3.5
-logarithmic functions                                      macro parameter, 6.10.3
-   complex, 7.3.7, G.6.3                                   macro preprocessor, 6.10
-   real, 7.12.6, F.10.3                                    macro replacement, 6.10.3
-logb functions, 7.12.6.11, F.3, F.10.3.11                  magnitude, complex, 7.3.8.1
-logb type-generic macro, 7.24                              main function, 5.1.2.2.1, 5.1.2.2.3, 6.7.3.1, 6.7.4,
-logical operators                                               7.21.3
-   AND (&&), 5.1.2.4, 6.5.13                               malloc function, 7.22.3, 7.22.3.4, 7.22.3.5
-   negation (!), 6.5.3.3                                   manipulation functions
-   OR (||), 5.1.2.4, 6.5.14                                  complex, 7.3.9
-logical source lines, 5.1.1.2                                real, 7.12.11, F.10.8
-long double _Complex type, 6.2.5                           matching failure, 7.28.2.6, 7.28.2.8, 7.28.2.10,
-
-[page 667] (Contents)
-
-     K.3.9.1.7, K.3.9.1.10, K.3.9.1.12                     modification order, 5.1.2.4
-math.h header, 5.2.4.2.2, 6.5, 7.12, 7.24, F,              modulus functions, 7.12.6.12
-     F.10, J.5.17                                          modulus, complex, 7.3.8.1
-MATH_ERREXCEPT macro, 7.12, F.10                           mtx_destroy function, 7.25.4.1
-math_errhandling macro, 7.1.3, 7.12, F.10                  mtx_init function, 7.25.1, 7.25.4.2
-MATH_ERRNO macro, 7.12                                     mtx_lock function, 7.25.4.3
-max_align_t type, 7.19                                     mtx_t type, 7.25.1
-maximum functions, 7.12.12, F.10.9                         mtx_timedlock function, 7.25.4.4
-MB_CUR_MAX macro, 7.1.1, 7.22, 7.22.7.2,                   mtx_trylock function, 7.25.4.5
-     7.22.7.3, 7.27.1.2, 7.27.1.4, 7.28.6.3.3,             mtx_unlock function, 7.25.4.3, 7.25.4.4,
-     K.3.6.4.1, K.3.9.3.1.1                                     7.25.4.5, 7.25.4.6
-MB_LEN_MAX macro, 5.2.4.2.1, 7.1.1, 7.22                   multibyte character, 3.7.2, 5.2.1.2, 6.4.4.4
-mblen function, 7.22.7.1, 7.28.6.3                         multibyte conversion functions
-mbrlen function, 7.28.6.3.1                                  wide character, 7.22.7, K.3.6.4
-mbrtoc16 function, 6.4.4.4, 6.4.5, 7.27.1.1                     extended, 7.28.6, K.3.9.3
-mbrtoc32 function, 6.4.4.4, 6.4.5, 7.27.1.3                     restartable, 7.27.1, 7.28.6.3, K.3.9.3.1
-mbrtowc function, 7.21.3, 7.21.6.1, 7.21.6.2,                wide string, 7.22.8, K.3.6.5
-     7.28.2.1, 7.28.2.2, 7.28.6.3.1, 7.28.6.3.2,                restartable, 7.28.6.4, K.3.9.3.2
-     7.28.6.4.1, K.3.6.5.1, K.3.9.3.2.1                    multibyte string, 7.1.1
-mbsinit function, 7.28.6.2.1                               multibyte/wide character conversion functions,
-mbsrtowcs function, 7.28.6.4.1, K.3.9.3.2                       7.22.7, K.3.6.4
-mbsrtowcs_s function, K.3.9.3.2, K.3.9.3.2.1                 extended, 7.28.6, K.3.9.3
-mbstate_t type, 7.21.2, 7.21.3, 7.21.6.1,                    restartable, 7.27.1, 7.28.6.3, K.3.9.3.1
-     7.21.6.2, 7.27, 7.27.1, 7.28.1, 7.28.2.1,             multibyte/wide string conversion functions,
-     7.28.2.2, 7.28.6, 7.28.6.2.1, 7.28.6.3,                    7.22.8, K.3.6.5
-     7.28.6.3.1, 7.28.6.4                                    restartable, 7.28.6.4, K.3.9.3.2
-mbstowcs function, 6.4.5, 7.22.8.1, 7.28.6.4               multidimensional array, 6.5.2.1
-mbstowcs_s function, K.3.6.5.1                             multiplication assignment operator (*=), 6.5.16.2
-mbtowc function, 6.4.4.4, 7.22.7.1, 7.22.7.2,              multiplication operator (*), 6.2.6.2, 6.5.5, F.3,
-     7.22.8.1, 7.28.6.3                                         G.5.1
-member access operators (. and ->), 6.5.2.3                multiplicative expressions, 6.5.5, G.5.1
-member alignment, 6.7.2.1
-memchr function, 7.23.5.1                                  n-char sequence, 7.22.1.3
-memcmp function, 7.23.4, 7.23.4.1                          n-wchar sequence, 7.28.4.1.1
-memcpy function, 7.23.2.1                                  name
-memcpy_s function, K.3.7.1.1                                 external, 5.2.4.1, 6.4.2.1, 6.11.3
-memmove function, 7.23.2.2                                   file, 7.21.3
-memmove_s function, K.3.7.1.2                                internal, 5.2.4.1, 6.4.2.1
-memory location, 3.14                                        label, 6.2.3
-memory management functions, 7.22.3                          structure/union member, 6.2.3
-memory_order type, 7.17.1, 7.17.3                          name spaces, 6.2.3
-memset function, 7.23.6.1, K.3.7.4.1                       named label, 6.8.1
-memset_s function, K.3.7.4.1                               NaN, 5.2.4.2.2
-minimum functions, 7.12.12, F.10.9                         nan functions, 7.12.11.2, F.2.1, F.10.8.2
-minus operator, unary, 6.5.3.3                             NAN macro, 7.12, F.2.1
-miscellaneous functions                                    NDEBUG macro, 7.2
-  string, 7.23.6, K.3.7.4                                  nearbyint functions, 7.12.9.3, 7.12.9.4, F.3,
-  wide string, 7.28.4.6, K.3.9.2.4                              F.10.6.3
-mktime function, 7.26.2.3                                  nearbyint type-generic macro, 7.24
-modf functions, 7.12.6.12, F.10.3.12                       nearest integer functions, 7.12.9, F.10.6
-modifiable lvalue, 6.3.2.1                                  negation operator (!), 6.5.3.3
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-[page 668] (Contents)
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-negative zero, 6.2.6.2, 7.12.11.1                               operator, 6.4.6
-new-line character, 5.1.1.2, 5.2.1, 6.4, 6.10, 6.10.4           operators, 6.5
-new-line escape sequence (\n), 5.2.2, 6.4.4.4,                     additive, 6.2.6.2, 6.5.6
-     7.4.1.10                                                      alignof, 6.5.3.4
-nextafter functions, 7.12.11.3, 7.12.11.4, F.3,                    assignment, 6.5.16
-     F.10.8.3                                                      associativity, 6.5
-nextafter type-generic macro, 7.24                                 equality, 6.5.9
-nexttoward functions, 7.12.11.4, F.3, F.10.8.4                     multiplicative, 6.2.6.2, 6.5.5, G.5.1
-nexttoward type-generic macro, 7.24                                postfix, 6.5.2
-no linkage, 6.2.2                                                  precedence, 6.5
-no-return function, 6.7.4                                          preprocessing, 6.10.1, 6.10.3.2, 6.10.3.3, 6.10.9
-non-stop floating-point control mode, 7.6.4.2                       relational, 6.5.8
-nongraphic characters, 5.2.2, 6.4.4.4                              shift, 6.5.7
-nonlocal jumps header, 7.13                                        sizeof, 6.5.3.4
-norm, complex, 7.3.8.1                                             unary, 6.5.3
-normalized broken-down time, K.3.8.1, K.3.8.2.1                    unary arithmetic, 6.5.3.3
-not macro, 7.9                                                  optional features, see conditional features
-not-equal-to operator, see inequality operator                  or macro, 7.9
-not_eq macro, 7.9                                               OR operators
-null character (\0), 5.2.1, 6.4.4.4, 6.4.5                         bitwise exclusive (^), 6.2.6.2, 6.5.11
-  padding of binary stream, 7.21.2                                 bitwise exclusive assignment (^=), 6.5.16.2
-NULL macro, 7.11, 7.19, 7.21.1, 7.22, 7.23.1,                      bitwise inclusive (|), 6.2.6.2, 6.5.12
-     7.26.1, 7.28.1                                                bitwise inclusive assignment (|=), 6.5.16.2
-null pointer, 6.3.2.3                                              logical (||), 5.1.2.4, 6.5.14
-null pointer constant, 6.3.2.3                                  or_eq macro, 7.9
-null preprocessing directive, 6.10.7                            order of allocated storage, 7.22.3
-null statement, 6.8.3                                           order of evaluation, 6.5, 6.5.16, 6.10.3.2, 6.10.3.3,
-null wide character, 7.1.1                                            see also sequence points
-number classification macros, 7.12, 7.12.3.1                     ordinary identifier name space, 6.2.3
-numeric conversion functions, 7.8.2.3, 7.22.1                   orientation of stream, 7.21.2, 7.28.3.5
-  wide string, 7.8.2.4, 7.28.4.1                                out-of-bounds store, L.2.1
-numerical limits, 5.2.4.2                                       outer scope, 6.2.1
-                                                                over-aligned, 6.2.8
-object, 3.15
-object representation, 6.2.6.1                                  padding
-object type, 6.2.5                                                binary stream, 7.21.2
-object-like macro, 6.10.3                                         bits, 6.2.6.2, 7.20.1.1
-observable behavior, 5.1.2.3                                      structure/union, 6.2.6.1, 6.7.2.1
-obsolescence, 6.11, 7.30                                        parameter, 3.16
-octal constant, 6.4.4.1                                           array, 6.9.1
-octal digit, 6.4.4.1, 6.4.4.4                                     ellipsis, 6.7.6.3, 6.10.3
-octal-character escape sequence (\octal digits),                  function, 6.5.2.2, 6.7, 6.9.1
-     6.4.4.4                                                      macro, 6.10.3
-offsetof macro, 7.19                                              main function, 5.1.2.2.1
-on-off switch, 6.10.6                                             program, 5.1.2.2.1
-once_flag type, 7.25.1                                          parameter type list, 6.7.6.3
-ONCE_FLAG_INIT macro, 7.25.1                                    parentheses punctuator (( )), 6.7.6.3, 6.8.4, 6.8.5
-ones' complement, 6.2.6.2                                       parenthesized expression, 6.5.1
-operand, 6.4.6, 6.5                                             parse state, 7.21.2
-operating system, 5.1.2.1, 7.22.4.8                             perform a trap, 3.19.5
-operations on files, 7.21.4, K.3.5.1                             permitted form of initializer, 6.6
-
-[page 669] (Contents)
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-perror function, 7.21.10.4                                    PRIcLEASTN macros, 7.8.1
-phase angle, complex, 7.3.9.1                                 PRIcMAX macros, 7.8.1
-physical source lines, 5.1.1.2                                PRIcN macros, 7.8.1
-placemarker, 6.10.3.3                                         PRIcPTR macros, 7.8.1
-plus operator, unary, 6.5.3.3                                 primary expression, 6.5.1
-pointer arithmetic, 6.5.6                                     printf function, 7.21.1, 7.21.6.3, 7.21.6.10,
-pointer comparison, 6.5.8                                           K.3.5.3.3
-pointer declarator, 6.7.6.1                                   printf_s function, K.3.5.3.3
-pointer operator (->), 6.5.2.3                                printing character, 5.2.2, 7.4, 7.4.1.8
-pointer to function, 6.5.2.2                                  printing wide character, 7.29.2
-pointer type, 6.2.5                                           program diagnostics, 7.2.1
-pointer type conversion, 6.3.2.1, 6.3.2.3                     program execution, 5.1.2.2.2, 5.1.2.3
-pointer, null, 6.3.2.3                                        program file, 5.1.1.1
-pole error, 7.12.1, 7.12.5.3, 7.12.6.7, 7.12.6.8,             program image, 5.1.1.2
-     7.12.6.9, 7.12.6.10, 7.12.6.11, 7.12.7.4,                program name (argv[0]), 5.1.2.2.1
-     7.12.8.3, 7.12.8.4                                       program parameters, 5.1.2.2.1
-portability, 4, J                                             program startup, 5.1.2, 5.1.2.1, 5.1.2.2.1
-position indicator, file, see file position indicator           program structure, 5.1.1.1
-positive difference, 7.12.12.1                                program termination, 5.1.2, 5.1.2.1, 5.1.2.2.3,
-positive difference functions, 7.12.12, F.10.9                      5.1.2.3
-postfix decrement operator (--), 6.3.2.1, 6.5.2.4              program, conforming, 4
-postfix expressions, 6.5.2                                     program, strictly conforming, 4
-postfix increment operator (++), 6.3.2.1, 6.5.2.4              promotions
-pow functions, 7.12.7.4, F.10.4.4                                default argument, 6.5.2.2
-pow type-generic macro, 7.24                                     integer, 5.1.2.3, 6.3.1.1
-power functions                                               prototype, see function prototype
-  complex, 7.3.8, G.6.4                                       pseudo-random sequence functions, 7.22.2
-  real, 7.12.7, F.10.4                                        PTRDIFF_MAX macro, 7.20.3
-pp-number, 6.4.8                                              PTRDIFF_MIN macro, 7.20.3
-pragma operator, 6.10.9                                       ptrdiff_t type, 7.17.1, 7.19, 7.20.3, 7.21.6.1,
-pragma preprocessing directive, 6.10.6, 6.11.8                      7.21.6.2, 7.28.2.1, 7.28.2.2
-precedence of operators, 6.5                                  punctuators, 6.4.6
-precedence of syntax rules, 5.1.1.2                           putc function, 7.21.1, 7.21.7.7, 7.21.7.8
-precision, 6.2.6.2, 6.3.1.1, 7.21.6.1, 7.28.2.1               putchar function, 7.21.1, 7.21.7.8
-  excess, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, 6.8.6.4                puts function, 7.21.1, 7.21.7.9
-predefined macro names, 6.10.8, 6.11.9                         putwc function, 7.21.1, 7.28.3.8, 7.28.3.9
-prefix decrement operator (--), 6.3.2.1, 6.5.3.1               putwchar function, 7.21.1, 7.28.3.9
-prefix increment operator (++), 6.3.2.1, 6.5.3.1
-preprocessing concatenation, 6.10.3.3                         qsort function, 7.22.5, 7.22.5.2
-preprocessing directives, 5.1.1.2, 6.10                       qsort_s function, K.3.6.3, K.3.6.3.2
-preprocessing file, 5.1.1.1, 6.10                              qualified types, 6.2.5
-preprocessing numbers, 6.4, 6.4.8                             qualified version of type, 6.2.5
-preprocessing operators                                       question-mark escape sequence (\?), 6.4.4.4
-  #, 6.10.3.2                                                 quick_exit function, 7.22.4.3, 7.22.4.4,
-  ##, 6.10.3.3                                                     7.22.4.7
-  _Pragma, 5.1.1.2, 6.10.9                                    quiet NaN, 5.2.4.2.2
-  defined, 6.10.1
-preprocessing tokens, 5.1.1.2, 6.4, 6.10                      raise function, 7.14, 7.14.1.1, 7.14.2.1, 7.22.4.1
-preprocessing translation unit, 5.1.1.1                       rand function, 7.22, 7.22.2.1, 7.22.2.2
-preprocessor, 6.10                                            RAND_MAX macro, 7.22, 7.22.2.1
-PRIcFASTN macros, 7.8.1                                       range
-
-[page 670] (Contents)
-
-   excess, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, 6.8.6.4              rewind function, 7.21.5.3, 7.21.7.10, 7.21.9.5,
-range error, 7.12.1, 7.12.5.4, 7.12.5.5, 7.12.6.1,                7.28.3.10
-      7.12.6.2, 7.12.6.3, 7.12.6.5, 7.12.6.6,                right-shift assignment operator (>>=), 6.5.16.2
-      7.12.6.13, 7.12.7.3, 7.12.7.4, 7.12.8.2,               right-shift operator (>>), 6.2.6.2, 6.5.7
-      7.12.8.3, 7.12.8.4, 7.12.9.5, 7.12.9.7,                rint functions, 7.12.9.4, F.3, F.10.6.4
-      7.12.11.3, 7.12.12.1, 7.12.13.1                        rint type-generic macro, 7.24
-rank, see integer conversion rank                            round functions, 7.12.9.6, F.10.6.6
-read-modify-write operations, 5.1.2.4                        round type-generic macro, 7.24
-real floating type conversion, 6.3.1.4, 6.3.1.5,              rounding mode, floating point, 5.2.4.2.2
-      6.3.1.7, F.3, F.4                                      RSIZE_MAX macro, K.3.3, K.3.4, K.3.5.1.2,
-real floating types, 6.2.5                                         K.3.5.3.5, K.3.5.3.6, K.3.5.3.12, K.3.5.3.13,
-real type domain, 6.2.5                                           K.3.5.4.1, K.3.6.2.1, K.3.6.3.1, K.3.6.3.2,
-real types, 6.2.5                                                 K.3.6.4.1, K.3.6.5.1, K.3.6.5.2, K.3.7.1.1,
-real-floating, 7.12.3                                              K.3.7.1.2, K.3.7.1.3, K.3.7.1.4, K.3.7.2.1,
-realloc function, 7.22.3, 7.22.3.5                                K.3.7.2.2, K.3.7.3.1, K.3.7.4.1, K.3.7.4.2,
-recommended practice, 3.17                                        K.3.8.2.1, K.3.8.2.2, K.3.9.1.3, K.3.9.1.4,
-recursion, 6.5.2.2                                                K.3.9.1.8, K.3.9.1.9, K.3.9.2.1.1, K.3.9.2.1.2,
-recursive function call, 6.5.2.2                                  K.3.9.2.1.3, K.3.9.2.1.4, K.3.9.2.2.1,
-redefinition of macro, 6.10.3                                      K.3.9.2.2.2, K.3.9.2.3.1, K.3.9.3.1.1,
-reentrancy, 5.1.2.3, 5.2.3                                        K.3.9.3.2.1, K.3.9.3.2.2
-   library functions, 7.1.4                                  rsize_t type, K.3.3, K.3.4, K.3.5, K.3.5.3.2,
-referenced type, 6.2.5                                            K.3.6, K.3.7, K.3.8, K.3.9, K.3.9.1.2
-register storage-class specifier, 6.7.1, 6.9                  runtime-constraint, 3.18
-relational expressions, 6.5.8                                Runtime-constraint handling functions, K.3.6.1
-relaxed atomic operations, 5.1.2.4                           rvalue, 6.3.2.1
-release fence, 7.17.4
-release operation, 5.1.2.4                                   same scope, 6.2.1
-release sequence, 5.1.2.4                                    save calling environment function, 7.13.1
-reliability of data, interrupted, 5.1.2.3                    scalar types, 6.2.5
-remainder assignment operator (%=), 6.5.16.2                 scalbln function, 7.12.6.13, F.3, F.10.3.13
-remainder functions, 7.12.10, F.10.7                         scalbln type-generic macro, 7.24
-remainder functions, 7.12.10.2, 7.12.10.3, F.3,              scalbn function, 7.12.6.13, F.3, F.10.3.13
-      F.10.7.2                                               scalbn type-generic macro, 7.24
-remainder operator (%), 6.2.6.2, 6.5.5                       scanf function, 7.21.1, 7.21.6.4, 7.21.6.11
-remainder type-generic macro, 7.24                           scanf_s function, K.3.5.3.4, K.3.5.3.11
-remove function, 7.21.4.1, 7.21.4.4, K.3.5.1.2               scanlist, 7.21.6.2, 7.28.2.2
-remquo functions, 7.12.10.3, F.3, F.10.7.3                   scanset, 7.21.6.2, 7.28.2.2
-remquo type-generic macro, 7.24                              SCHAR_MAX macro, 5.2.4.2.1
-rename function, 7.21.4.2                                    SCHAR_MIN macro, 5.2.4.2.1
-representations of types, 6.2.6                              SCNcFASTN macros, 7.8.1
-   pointer, 6.2.5                                            SCNcLEASTN macros, 7.8.1
-rescanning and replacement, 6.10.3.4                         SCNcMAX macros, 7.8.1
-reserved identifiers, 6.4.1, 7.1.3, K.3.1.2                   SCNcN macros, 7.8.1
-restartable multibyte/wide character conversion              SCNcPTR macros, 7.8.1
-      functions, 7.27.1, 7.28.6.3, K.3.9.3.1                 scope of identifier, 6.2.1, 6.9.2
-restartable multibyte/wide string conversion                 search functions
-      functions, 7.28.6.4, K.3.9.3.2                           string, 7.23.5, K.3.7.3
-restore calling environment function, 7.13.2                   utility, 7.22.5, K.3.6.3
-restrict type qualifier, 6.7.3, 6.7.3.1                         wide string, 7.28.4.5, K.3.9.2.3
-restrict-qualified type, 6.2.5, 6.7.3                         SEEK_CUR macro, 7.21.1, 7.21.9.2
-return statement, 6.8.6.4, F.6                               SEEK_END macro, 7.21.1, 7.21.9.2
-
-[page 671] (Contents)
-
-SEEK_SET macro, 7.21.1, 7.21.9.2                                 signal function, 7.14.1.1, 7.22.4.5, 7.22.4.7
-selection statements, 6.8.4                                      signal handler, 5.1.2.3, 5.2.3, 7.14.1.1, 7.14.2.1
-self-referential structure, 6.7.2.3                              signal handling functions, 7.14.1
-semicolon punctuator (;), 6.7, 6.7.2.1, 6.8.3,                   signal.h header, 7.14, 7.30.6
-      6.8.5, 6.8.6                                               signaling NaN, 5.2.4.2.2, F.2.1
-separate compilation, 5.1.1.1                                    signals, 5.1.2.3, 5.2.3, 7.14.1
-separate translation, 5.1.1.1                                    signbit macro, 7.12.3.6, F.3
-sequence points, 5.1.2.3, 6.5.2.2, 6.5.13, 6.5.14,               signed char type, 6.2.5, 7.21.6.1, 7.21.6.2,
-      6.5.15, 6.5.17, 6.7.3, 6.7.3.1, 6.7.6, 6.8,                     7.28.2.1, 7.28.2.2, K.3.5.3.2, K.3.9.1.2
-      7.1.4, 7.21.6, 7.22.5, 7.28.2, C, K.3.6.3                  signed character, 6.3.1.1
-sequenced after, see sequenced before                            signed integer types, 6.2.5, 6.3.1.3, 6.4.4.1
-sequenced before, 5.1.2.3, 6.5, 6.5.2.2, 6.5.2.4,                signed type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4,
-      6.5.16, see also indeterminately sequenced,                     6.3.1.8
-      unsequenced                                                signed types, 6.2.5, 6.7.2
-sequencing of statements, 6.8                                    significand part, 6.4.4.2
-set_constraint_handler_s function,                               SIGSEGV macro, 7.14, 7.14.1.1
-      K.3.1.4, K.3.6.1.1, K.3.6.1.2, K.3.6.1.3                   SIGTERM macro, 7.14
-setbuf function, 7.21.3, 7.21.5.1, 7.21.5.5                      simple assignment operator (=), 6.5.16.1
-setjmp macro, 7.1.3, 7.13.1.1, 7.13.2.1                          sin functions, 7.12.4.6, F.10.1.6
-setjmp.h header, 7.13                                            sin type-generic macro, 7.24, G.7
-setlocale function, 7.11.1.1, 7.11.2.1                           single-byte character, 3.7.1, 5.2.1.2
-setvbuf function, 7.21.1, 7.21.3, 7.21.5.1,                      single-byte/wide character conversion functions,
-      7.21.5.5, 7.21.5.6                                              7.28.6.1
-shall, 4                                                         single-precision arithmetic, 5.1.2.3
-shift expressions, 6.5.7                                         single-quote escape sequence (\'), 6.4.4.4, 6.4.5
-shift sequence, 7.1.1                                            singularity, 7.12.1
-shift states, 5.2.1.2                                            sinh functions, 7.12.5.5, F.10.2.5
-short identifier, character, 5.2.4.1, 6.4.3                       sinh type-generic macro, 7.24, G.7
-short int type, 6.2.5, 6.3.1.1, 6.7.2, 7.21.6.1,                 SIZE_MAX macro, 7.20.3
-      7.21.6.2, 7.28.2.1, 7.28.2.2                               size_t type, 6.2.8, 6.5.3.4, 7.19, 7.20.3, 7.21.1,
-short int type conversion, 6.3.1.1, 6.3.1.3,                          7.21.6.1, 7.21.6.2, 7.22, 7.23.1, 7.26.1, 7.27,
-      6.3.1.4, 6.3.1.8                                                7.28.1, 7.28.2.1, 7.28.2.2, K.3.3, K.3.4,
-SHRT_MAX macro, 5.2.4.2.1                                             K.3.5, K.3.6, K.3.7, K.3.8, K.3.9, K.3.9.1.2
-SHRT_MIN macro, 5.2.4.2.1                                        sizeof operator, 6.3.2.1, 6.5.3, 6.5.3.4
-side effects, 5.1.2.3, 6.2.6.1, 6.3.2.2, 6.5, 6.5.2.4,           snprintf function, 7.21.6.5, 7.21.6.12,
-      6.5.16, 6.7.9, 6.8.3, 7.6, 7.6.1, 7.21.7.5,                     K.3.5.3.5
-      7.21.7.7, 7.28.3.6, 7.28.3.8, F.8.1, F.9.1,                snprintf_s function, K.3.5.3.5, K.3.5.3.6
-      F.9.3                                                      snwprintf_s function, K.3.9.1.3, K.3.9.1.4
-SIG_ATOMIC_MAX macro, 7.20.3                                     sorting utility functions, 7.22.5, K.3.6.3
-SIG_ATOMIC_MIN macro, 7.20.3                                     source character set, 5.1.1.2, 5.2.1
-sig_atomic_t type, 5.1.2.3, 7.14, 7.14.1.1,                      source file, 5.1.1.1
-      7.20.3                                                        name, 6.10.4, 6.10.8.1
-SIG_DFL macro, 7.14, 7.14.1.1                                    source file inclusion, 6.10.2
-SIG_ERR macro, 7.14, 7.14.1.1                                    source lines, 5.1.1.2
-SIG_IGN macro, 7.14, 7.14.1.1                                    source text, 5.1.1.2
-SIGABRT macro, 7.14, 7.22.4.1                                    space character (' '), 5.1.1.2, 5.2.1, 6.4, 7.4.1.3,
-SIGFPE macro, 7.12.1, 7.14, 7.14.1.1, J.5.17                          7.4.1.10, 7.29.2.1.3
-SIGILL macro, 7.14, 7.14.1.1                                     sprintf function, 7.21.6.6, 7.21.6.13, K.3.5.3.6
-SIGINT macro, 7.14                                               sprintf_s function, K.3.5.3.5, K.3.5.3.6
-sign and magnitude, 6.2.6.2                                      sqrt functions, 7.12.7.5, F.3, F.10.4.5
-sign bit, 6.2.6.2                                                sqrt type-generic macro, 7.24
-
-[page 672] (Contents)
-
-srand function, 7.22.2.2                                        expression, 6.8.3
-sscanf function, 7.21.6.7, 7.21.6.14                            for, 6.8.5.3
-sscanf_s function, K.3.5.3.7, K.3.5.3.14                        goto, 6.8.6.1
-standard error stream, 7.21.1, 7.21.3, 7.21.10.4                if, 6.8.4.1
-standard headers, 4, 7.1.2                                      iteration, 6.8.5
-   <assert.h>, 7.2                                              jump, 6.8.6
-   <complex.h>, 5.2.4.2.2, 6.10.8.3, 7.1.2, 7.3,                labeled, 6.8.1
-        7.24, 7.30.1, G.6, J.5.17                               null, 6.8.3
-   <ctype.h>, 7.4, 7.30.2                                       return, 6.8.6.4, F.6
-   <errno.h>, 7.5, 7.30.3, K.3.2                                selection, 6.8.4
-   <fenv.h>, 5.1.2.3, 5.2.4.2.2, 7.6, 7.12, F, H                sequencing, 6.8
-   <float.h>, 4, 5.2.4.2.2, 7.7, 7.22.1.3,                      switch, 6.8.4.2
-        7.28.4.1.1                                              while, 6.8.5.1
-   <inttypes.h>, 7.8, 7.30.4                                 static assertions, 6.7.10
-   <iso646.h>, 4, 7.9                                        static storage duration, 6.2.4
-   <limits.h>, 4, 5.2.4.2.1, 6.2.5, 7.10                     static storage-class specifier, 6.2.2, 6.2.4, 6.7.1
-   <locale.h>, 7.11, 7.30.5                                  static, in array declarators, 6.7.6.2, 6.7.6.3
-   <math.h>, 5.2.4.2.2, 6.5, 7.12, 7.24, F, F.10,            static_assert declaration, 6.7.10
-        J.5.17                                               static_assert macro, 7.2
-   <setjmp.h>, 7.13                                          stdalign.h header, 4, 7.15
-   <signal.h>, 7.14, 7.30.6                                  stdarg.h header, 4, 6.7.6.3, 7.16
-   <stdalign.h>, 4, 7.15                                     stdatomic.h header, 6.10.8.3, 7.1.2, 7.17
-   <stdarg.h>, 4, 6.7.6.3, 7.16                              stdbool.h header, 4, 7.18, 7.30.7, H
-   <stdatomic.h>, 6.10.8.3, 7.1.2, 7.17                      STDC, 6.10.6, 6.11.8
-   <stdbool.h>, 4, 7.18, 7.30.7, H                           stddef.h header, 4, 6.3.2.1, 6.3.2.3, 6.4.4.4,
-   <stddef.h>, 4, 6.3.2.1, 6.3.2.3, 6.4.4.4,                       6.4.5, 6.5.3.4, 6.5.6, 7.19, K.3.3
-        6.4.5, 6.5.3.4, 6.5.6, 7.19, K.3.3                   stderr macro, 7.21.1, 7.21.2, 7.21.3
-   <stdint.h>, 4, 5.2.4.2, 6.10.1, 7.8, 7.20,                stdin macro, 7.21.1, 7.21.2, 7.21.3, 7.21.6.4,
-        7.30.8, K.3.3, K.3.4                                       7.21.7.6, 7.28.2.12, 7.28.3.7, K.3.5.3.4,
-   <stdio.h>, 5.2.4.2.2, 7.21, 7.30.9, F, K.3.5                    K.3.5.4.1, K.3.9.1.14
-   <stdlib.h>, 5.2.4.2.2, 7.22, 7.30.10, F,                  stdint.h header, 4, 5.2.4.2, 6.10.1, 7.8, 7.20,
-        K.3.1.4, K.3.6                                             7.30.8, K.3.3, K.3.4
-   <string.h>, 7.23, 7.30.11, K.3.7                          stdio.h header, 5.2.4.2.2, 7.21, 7.30.9, F, K.3.5
-   <tgmath.h>, 7.24, G.7                                     stdlib.h header, 5.2.4.2.2, 7.22, 7.30.10, F,
-   <threads.h>, 6.10.8.3, 7.1.2, 7.25                              K.3.1.4, K.3.6
-   <time.h>, 7.26, K.3.8                                     stdout macro, 7.21.1, 7.21.2, 7.21.3, 7.21.6.3,
-   <uchar.h>, 6.4.4.4, 6.4.5, 7.27                                 7.21.7.8, 7.21.7.9, 7.28.2.11, 7.28.3.9
-   <wchar.h>, 5.2.4.2.2, 7.21.1, 7.28, 7.30.12,              storage duration, 6.2.4
-        F, K.3.9                                             storage order of array, 6.5.2.1
-   <wctype.h>, 7.29, 7.30.13                                 storage unit (bit-field), 6.2.6.1, 6.7.2.1
-standard input stream, 7.21.1, 7.21.3                        storage-class specifiers, 6.7.1, 6.11.5
-standard integer types, 6.2.5                                strcat function, 7.23.3.1
-standard output stream, 7.21.1, 7.21.3                       strcat_s function, K.3.7.2.1
-standard signed integer types, 6.2.5                         strchr function, 7.23.5.2
-state-dependent encoding, 5.2.1.2, 7.22.7, K.3.6.4           strcmp function, 7.23.4, 7.23.4.2
-statements, 6.8                                              strcoll function, 7.11.1.1, 7.23.4.3, 7.23.4.5
-   break, 6.8.6.3                                            strcpy function, 7.23.2.3
-   compound, 6.8.2                                           strcpy_s function, K.3.7.1.3
-   continue, 6.8.6.2                                         strcspn function, 7.23.5.3
-   do, 6.8.5.2                                               streams, 7.21.2, 7.22.4.4
-   else, 6.8.4.1                                                fully buffered, 7.21.3
-
-[page 673] (Contents)
-
-   line buffered, 7.21.3                                           strtoumax function, 7.8.2.3
-   orientation, 7.21.2                                             struct hack, see flexible array member
-   standard error, 7.21.1, 7.21.3                                  struct lconv, 7.11
-   standard input, 7.21.1, 7.21.3                                  struct tm, 7.26.1
-   standard output, 7.21.1, 7.21.3                                 structure
-   unbuffered, 7.21.3                                                 arrow operator (->), 6.5.2.3
-strerror function, 7.21.10.4, 7.23.6.2                                content, 6.7.2.3
-strerror_s function, K.3.7.4.2, K.3.7.4.3                             dot operator (.), 6.5.2.3
-strerrorlen_s function, K.3.7.4.3                                     initialization, 6.7.9
-strftime function, 7.11.1.1, 7.26.3, 7.26.3.5,                        member alignment, 6.7.2.1
-      7.28.5.1, K.3.8.2, K.3.8.2.1, K.3.8.2.2                         member name space, 6.2.3
-stricter, 6.2.8                                                       member operator (.), 6.3.2.1, 6.5.2.3
-strictly conforming program, 4                                        pointer operator (->), 6.5.2.3
-string, 7.1.1                                                         specifier, 6.7.2.1
-   comparison functions, 7.23.4                                       tag, 6.2.3, 6.7.2.3
-   concatenation functions, 7.23.3, K.3.7.2                           type, 6.2.5, 6.7.2.1
-   conversion functions, 7.11.1.1                                  strxfrm function, 7.11.1.1, 7.23.4.5
-   copying functions, 7.23.2, K.3.7.1                              subnormal floating-point numbers, 5.2.4.2.2
-   library function conventions, 7.23.1                            subscripting, 6.5.2.1
-   literal, 5.1.1.2, 5.2.1, 6.3.2.1, 6.4.5, 6.5.1, 6.7.9           subtraction assignment operator (-=), 6.5.16.2
-   miscellaneous functions, 7.23.6, K.3.7.4                        subtraction operator (-), 6.2.6.2, 6.5.6, F.3, G.5.2
-   numeric conversion functions, 7.8.2.3, 7.22.1                   suffix
-   search functions, 7.23.5, K.3.7.3                                  floating constant, 6.4.4.2
-string handling header, 7.23, K.3.7                                   integer constant, 6.4.4.1
-string.h header, 7.23, 7.30.11, K.3.7                              switch body, 6.8.4.2
-stringizing, 6.10.3.2, 6.10.9                                      switch case label, 6.8.1, 6.8.4.2
-strlen function, 7.23.6.3                                          switch default label, 6.8.1, 6.8.4.2
-strncat function, 7.23.3.2                                         switch statement, 6.8.1, 6.8.4.2
-strncat_s function, K.3.7.2.2                                      swprintf function, 7.28.2.3, 7.28.2.7,
-strncmp function, 7.23.4, 7.23.4.4                                       K.3.9.1.3, K.3.9.1.4
-strncpy function, 7.23.2.4                                         swprintf_s function, K.3.9.1.3, K.3.9.1.4
-strncpy_s function, K.3.7.1.4                                      swscanf function, 7.28.2.4, 7.28.2.8
-strnlen_s function, K.3.7.4.4                                      swscanf_s function, K.3.9.1.5, K.3.9.1.10
-stronger, 6.2.8                                                    symbols, 3
-strpbrk function, 7.23.5.4                                         synchronization operation, 5.1.2.4
-strrchr function, 7.23.5.5                                         synchronize with, 5.1.2.4
-strspn function, 7.23.5.6                                          syntactic categories, 6.1
-strstr function, 7.23.5.7                                          syntax notation, 6.1
-strtod function, 7.12.11.2, 7.21.6.2, 7.22.1.3,                    syntax rule precedence, 5.1.1.2
-      7.28.2.2, F.3                                                syntax summary, language, A
-strtof function, 7.12.11.2, 7.22.1.3, F.3                          system function, 7.22.4.8
-strtoimax function, 7.8.2.3
-strtok function, 7.23.5.8                                          tab characters, 5.2.1, 6.4
-strtok_s function, K.3.7.3.1                                       tag compatibility, 6.2.7
-strtol function, 7.8.2.3, 7.21.6.2, 7.22.1.2,                      tag name space, 6.2.3
-      7.22.1.4, 7.28.2.2                                           tags, 6.7.2.3
-strtold function, 7.12.11.2, 7.22.1.3, F.3                         tan functions, 7.12.4.7, F.10.1.7
-strtoll function, 7.8.2.3, 7.22.1.2, 7.22.1.4                      tan type-generic macro, 7.24, G.7
-strtoul function, 7.8.2.3, 7.21.6.2, 7.22.1.2,                     tanh functions, 7.12.5.6, F.10.2.6
-      7.22.1.4, 7.28.2.2                                           tanh type-generic macro, 7.24, G.7
-strtoull function, 7.8.2.3, 7.22.1.2, 7.22.1.4                     temporary lifetime, 6.2.4
-
-[page 674] (Contents)
-
-tentative definition, 6.9.2                                    towlower function, 7.29.3.1.1, 7.29.3.2.1
-terms, 3                                                      towupper function, 7.29.3.1.2, 7.29.3.2.1
-text streams, 7.21.2, 7.21.7.10, 7.21.9.2, 7.21.9.4           translation environment, 5, 5.1.1
-tgamma functions, 7.12.8.4, F.10.5.4                          translation limits, 5.2.4.1
-tgamma type-generic macro, 7.24                               translation phases, 5.1.1.2
-tgmath.h header, 7.24, G.7                                    translation unit, 5.1.1.1, 6.9
-thrd_create function, 7.25.1, 7.25.5.1                        trap, see perform a trap
-thrd_current function, 7.25.5.2                               trap representation, 3.19.4, 6.2.6.1, 6.2.6.2,
-thrd_detach function, 7.25.5.3, 7.25.5.6                            6.3.2.3, 6.5.2.3
-thrd_equal function, 7.25.5.4                                 trigonometric functions
-thrd_exit function, 7.25.5.5                                     complex, 7.3.5, G.6.1
-thrd_join function, 7.25.5.3, 7.25.5.6                           real, 7.12.4, F.10.1
-thrd_sleep function, 7.25.5.7                                 trigraph sequences, 5.1.1.2, 5.2.1.1
-thrd_start_t type, 7.25.1                                     true macro, 7.18
-thrd_t type, 7.25.1                                           trunc functions, 7.12.9.8, F.10.6.8
-thrd_yield function, 7.25.5.8                                 trunc type-generic macro, 7.24
-thread of execution, 5.1.2.4, 7.1.4, 7.6, 7.22.4.6            truncation, 6.3.1.4, 7.12.9.8, 7.21.3, 7.21.5.3
-thread storage duration, 6.2.4, 7.6                           truncation toward zero, 6.5.5
-threads header, 7.25                                          tss_create function, 7.25.6.1
-threads.h header, 6.10.8.3, 7.1.2, 7.25                       tss_delete function, 7.25.6.2
-time                                                          TSS_DTOR_ITERATIONS macro, 7.25.1
-   broken down, 7.26.1, 7.26.2.3, 7.26.3, 7.26.3.1,           tss_dtor_t type, 7.25.1
-         7.26.3.3, 7.26.3.4, 7.26.3.5, K.3.8.2.1,             tss_get function, 7.25.6.3
-         K.3.8.2.3, K.3.8.2.4                                 tss_set function, 7.25.6.4
-   calendar, 7.26.1, 7.26.2.2, 7.26.2.3, 7.26.2.4,            tss_t type, 7.25.1
-         7.26.3.2, 7.26.3.3, 7.26.3.4, K.3.8.2.2,             two's complement, 6.2.6.2, 7.20.1.1
-         K.3.8.2.3, K.3.8.2.4                                 type category, 6.2.5
-   components, 7.26.1, K.3.8.1                                type conversion, 6.3
-   conversion functions, 7.26.3, K.3.8.2                      type definitions, 6.7.8
-      wide character, 7.28.5                                  type domain, 6.2.5, G.2
-   local, 7.26.1                                              type names, 6.7.7
-   manipulation functions, 7.26.2                             type punning, 6.5.2.3
-   normalized broken down, K.3.8.1, K.3.8.2.1                 type qualifiers, 6.7.3
-time function, 7.26.2.4                                       type specifiers, 6.7.2
-time.h header, 7.26, K.3.8                                    type-generic macro, 7.24, G.7
-time_t type, 7.26.1                                           typedef declaration, 6.7.8
-TIME_UTC macro, 7.25.7.1                                      typedef storage-class specifier, 6.7.1, 6.7.8
-tm structure type, 7.26.1, 7.28.1, K.3.8.1                    types, 6.2.5
-TMP_MAX macro, 7.21.1, 7.21.4.3, 7.21.4.4                        _Atomic qualified, 6.2.5, 6.2.6.1, 6.5.2.3,
-TMP_MAX_S macro, K.3.5, K.3.5.1.1, K.3.5.1.2                           6.5.2.4, 6.5.16.2, 6.7.2, 6.7.3
-tmpfile function, 7.21.4.3, 7.22.4.4                             atomic, 5.1.2.3, 6.10.8.3, 7.17.6
-tmpfile_s function, K.3.5.1.1, K.3.5.1.2                         character, 6.7.9
-tmpnam function, 7.21.1, 7.21.4.3, 7.21.4.4,                     compatible, 6.2.7, 6.7.2, 6.7.3, 6.7.6
-      K.3.5.1.2                                                  complex, 6.2.5, G
-tmpnam_s function, K.3.5, K.3.5.1.1, K.3.5.1.2                   composite, 6.2.7
-token, 5.1.1.2, 6.4, see also preprocessing tokens               const qualified, 6.7.3
-token concatenation, 6.10.3.3                                    conversions, 6.3
-token pasting, 6.10.3.3                                          imaginary, G
-tolower function, 7.4.2.1                                        restrict qualified, 6.7.3
-toupper function, 7.4.2.2                                        volatile qualified, 6.7.3
-towctrans function, 7.29.3.2.1, 7.29.3.2.2
-
-[page 675] (Contents)
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-uchar.h header, 6.4.4.4, 6.4.5, 7.27                      universal character name, 6.4.3
-UCHAR_MAX macro, 5.2.4.2.1                                unnormalized floating-point numbers, 5.2.4.2.2
-UINT_FASTN_MAX macros, 7.20.2.3                           unqualified type, 6.2.5
-uint_fastN_t types, 7.20.1.3                              unqualified version of type, 6.2.5
-uint_least16_t type, 7.27                                 unsequenced, 5.1.2.3, 6.5, 6.5.16, see also
-uint_least32_t type, 7.27                                       indeterminately sequenced, sequenced
-UINT_LEASTN_MAX macros, 7.20.2.2                                before
-uint_leastN_t types, 7.20.1.2                             unsigned char type, K.3.5.3.2, K.3.9.1.2
-UINT_MAX macro, 5.2.4.2.1                                 unsigned integer suffix, u or U, 6.4.4.1
-UINTMAX_C macro, 7.20.4.2                                 unsigned integer types, 6.2.5, 6.3.1.3, 6.4.4.1
-UINTMAX_MAX macro, 7.8.2.3, 7.8.2.4, 7.20.2.5             unsigned type conversion, 6.3.1.1, 6.3.1.3,
-uintmax_t type, 7.20.1.5, 7.21.6.1, 7.21.6.2,                   6.3.1.4, 6.3.1.8
-     7.28.2.1, 7.28.2.2                                   unsigned types, 6.2.5, 6.7.2, 7.21.6.1, 7.21.6.2,
-UINTN_C macros, 7.20.4.1                                        7.28.2.1, 7.28.2.2
-UINTN_MAX macros, 7.20.2.1                                unspecified behavior, 3.4.4, 4, J.1
-uintN_t types, 7.20.1.1                                   unspecified value, 3.19.3
-UINTPTR_MAX macro, 7.20.2.4                               uppercase letter, 5.2.1
-uintptr_t type, 7.20.1.4                                  use of library functions, 7.1.4
-ULLONG_MAX macro, 5.2.4.2.1, 7.22.1.4,                    USHRT_MAX macro, 5.2.4.2.1
-     7.28.4.1.2                                           usual arithmetic conversions, 6.3.1.8, 6.5.5, 6.5.6,
-ULONG_MAX macro, 5.2.4.2.1, 7.22.1.4,                           6.5.8, 6.5.9, 6.5.10, 6.5.11, 6.5.12, 6.5.15
-     7.28.4.1.2                                           UTF-16, 6.10.8.2
-unary arithmetic operators, 6.5.3.3                       UTF-32, 6.10.8.2
-unary expression, 6.5.3                                   UTF-8 string literal, see string literal
-unary minus operator (-), 6.5.3.3, F.3                    utilities, general, 7.22, K.3.6
-unary operators, 6.5.3                                       wide string, 7.28.4, K.3.9.2
-unary plus operator (+), 6.5.3.3
-unbuffered stream, 7.21.3                                 va_arg macro, 7.16, 7.16.1, 7.16.1.1, 7.16.1.2,
-undef preprocessing directive, 6.10.3.5, 7.1.3,                7.16.1.4, 7.21.6.8, 7.21.6.9, 7.21.6.10,
-     7.1.4                                                     7.21.6.11, 7.21.6.12, 7.21.6.13, 7.21.6.14,
-undefined behavior, 3.4.3, 4, J.2                               7.28.2.5, 7.28.2.6, 7.28.2.7, 7.28.2.8,
-underscore character, 6.4.2.1                                  7.28.2.9, 7.28.2.10, K.3.5.3.9, K.3.5.3.11,
-underscore, leading, in identifier, 7.1.3                       K.3.5.3.14, K.3.9.1.7, K.3.9.1.10, K.3.9.1.12
-ungetc function, 7.21.1, 7.21.7.10, 7.21.9.2,             va_copy macro, 7.1.3, 7.16, 7.16.1, 7.16.1.1,
-     7.21.9.3                                                  7.16.1.2, 7.16.1.3
-ungetwc function, 7.21.1, 7.28.3.10                       va_end macro, 7.1.3, 7.16, 7.16.1, 7.16.1.3,
-Unicode, 7.27, see also char16_t type,                         7.16.1.4, 7.21.6.8, 7.21.6.9, 7.21.6.10,
-     char32_t type, wchar_t type                               7.21.6.11, 7.21.6.12, 7.21.6.13, 7.21.6.14,
-Unicode required set, 6.10.8.2                                 7.28.2.5, 7.28.2.6, 7.28.2.7, 7.28.2.8,
-union                                                          7.28.2.9, 7.28.2.10, K.3.5.3.9, K.3.5.3.11,
-  arrow operator (->), 6.5.2.3                                 K.3.5.3.14, K.3.9.1.7, K.3.9.1.10, K.3.9.1.12
-  content, 6.7.2.3                                        va_list type, 7.16, 7.16.1.3
-  dot operator (.), 6.5.2.3                               va_start macro, 7.16, 7.16.1, 7.16.1.1,
-  initialization, 6.7.9                                        7.16.1.2, 7.16.1.3, 7.16.1.4, 7.21.6.8,
-  member alignment, 6.7.2.1                                    7.21.6.9, 7.21.6.10, 7.21.6.11, 7.21.6.12,
-  member name space, 6.2.3                                     7.21.6.13, 7.21.6.14, 7.28.2.5, 7.28.2.6,
-  member operator (.), 6.3.2.1, 6.5.2.3                        7.28.2.7, 7.28.2.8, 7.28.2.9, 7.28.2.10,
-  pointer operator (->), 6.5.2.3                               K.3.5.3.9, K.3.5.3.11, K.3.5.3.14, K.3.9.1.7,
-  specifier, 6.7.2.1                                            K.3.9.1.10, K.3.9.1.12
-  tag, 6.2.3, 6.7.2.3                                     value, 3.19
-  type, 6.2.5, 6.7.2.1                                    value bits, 6.2.6.2
-
-[page 676] (Contents)
-
-variable arguments, 6.10.3, 7.16                             vswscanf function, 7.28.2.8
-variable arguments header, 7.16                              vswscanf_s function, K.3.9.1.10
-variable length array, 6.7.6, 6.7.6.2, 6.10.8.3              vwprintf function, 7.21.1, 7.28.2.9, K.3.9.1.11
-variably modified type, 6.7.6, 6.7.6.2, 6.10.8.3              vwprintf_s function, K.3.9.1.11
-vertical-tab character, 5.2.1, 6.4                           vwscanf function, 7.21.1, 7.28.2.10, 7.28.3.10
-vertical-tab escape sequence (\v), 5.2.2, 6.4.4.4,           vwscanf_s function, K.3.9.1.12
-     7.4.1.10
-vfprintf function, 7.21.1, 7.21.6.8, K.3.5.3.8               warnings, I
-vfprintf_s function, K.3.5.3.8, K.3.5.3.9,                   wchar.h header, 5.2.4.2.2, 7.21.1, 7.28, 7.30.12,
-     K.3.5.3.11, K.3.5.3.14                                      F, K.3.9
-vfscanf function, 7.21.1, 7.21.6.8, 7.21.6.9                 WCHAR_MAX macro, 7.20.3, 7.28.1
-vfscanf_s function, K.3.5.3.9, K.3.5.3.11,                   WCHAR_MIN macro, 7.20.3, 7.28.1
-     K.3.5.3.14                                              wchar_t type, 3.7.3, 6.4.5, 6.7.9, 6.10.8.2, 7.19,
-vfwprintf function, 7.21.1, 7.28.2.5, K.3.9.1.6                  7.20.3, 7.21.6.1, 7.21.6.2, 7.22, 7.28.1,
-vfwprintf_s function, K.3.9.1.6                                  7.28.2.1, 7.28.2.2
-vfwscanf function, 7.21.1, 7.28.2.6, 7.28.3.10               wcrtomb function, 7.21.3, 7.21.6.2, 7.28.2.2,
-vfwscanf_s function, K.3.9.1.7                                   7.28.6.3.3, 7.28.6.4.2, K.3.6.5.2, K.3.9.3.1,
-visibility of identifier, 6.2.1                                   K.3.9.3.2.2
-visible sequence of side effects, 5.1.2.4                    wcrtomb_s function, K.3.9.3.1, K.3.9.3.1.1
-visible side effect, 5.1.2.4                                 wcscat function, 7.28.4.3.1
-VLA, see variable length array                               wcscat_s function, K.3.9.2.2.1
-void expression, 6.3.2.2                                     wcschr function, 7.28.4.5.1
-void function parameter, 6.7.6.3                             wcscmp function, 7.28.4.4.1, 7.28.4.4.4
-void type, 6.2.5, 6.3.2.2, 6.7.2, K.3.5.3.2,                 wcscoll function, 7.28.4.4.2, 7.28.4.4.4
-     K.3.9.1.2                                               wcscpy function, 7.28.4.2.1
-void type conversion, 6.3.2.2                                wcscpy_s function, K.3.9.2.1.1
-volatile storage, 5.1.2.3                                    wcscspn function, 7.28.4.5.2
-volatile type qualifier, 6.7.3                                wcsftime function, 7.11.1.1, 7.28.5.1
-volatile-qualified type, 6.2.5, 6.7.3                         wcslen function, 7.28.4.6.1
-vprintf function, 7.21.1, 7.21.6.8, 7.21.6.10,               wcsncat function, 7.28.4.3.2
-     K.3.5.3.10                                              wcsncat_s function, K.3.9.2.2.2
-vprintf_s function, K.3.5.3.9, K.3.5.3.10,                   wcsncmp function, 7.28.4.4.3
-     K.3.5.3.11, K.3.5.3.14                                  wcsncpy function, 7.28.4.2.2
-vscanf function, 7.21.1, 7.21.6.8, 7.21.6.11                 wcsncpy_s function, K.3.9.2.1.2
-vscanf_s function, K.3.5.3.9, K.3.5.3.11,                    wcsnlen_s function, K.3.9.2.4.1
-     K.3.5.3.14                                              wcspbrk function, 7.28.4.5.3
-vsnprintf function, 7.21.6.8, 7.21.6.12,                     wcsrchr function, 7.28.4.5.4
-     K.3.5.3.12                                              wcsrtombs function, 7.28.6.4.2, K.3.9.3.2
-vsnprintf_s function, K.3.5.3.9, K.3.5.3.11,                 wcsrtombs_s function, K.3.9.3.2, K.3.9.3.2.2
-     K.3.5.3.12, K.3.5.3.13, K.3.5.3.14                      wcsspn function, 7.28.4.5.5
-vsnwprintf_s function, K.3.9.1.8, K.3.9.1.9                  wcsstr function, 7.28.4.5.6
-vsprintf function, 7.21.6.8, 7.21.6.13,                      wcstod function, 7.21.6.2, 7.28.2.2
-     K.3.5.3.13                                              wcstod function, 7.28.4.1.1
-vsprintf_s function, K.3.5.3.9, K.3.5.3.11,                  wcstof function, 7.28.4.1.1
-     K.3.5.3.12, K.3.5.3.13, K.3.5.3.14                      wcstoimax function, 7.8.2.4
-vsscanf function, 7.21.6.8, 7.21.6.14                        wcstok function, 7.28.4.5.7
-vsscanf_s function, K.3.5.3.9, K.3.5.3.11,                   wcstok_s function, K.3.9.2.3.1
-     K.3.5.3.14                                              wcstol function, 7.8.2.4, 7.21.6.2, 7.28.2.2,
-vswprintf function, 7.28.2.7, K.3.9.1.8,                         7.28.4.1.2
-     K.3.9.1.9                                               wcstold function, 7.28.4.1.1
-vswprintf_s function, K.3.9.1.8, K.3.9.1.9                   wcstoll function, 7.8.2.4, 7.28.4.1.2
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-[page 677] (Contents)
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-wcstombs function, 7.22.8.2, 7.28.6.4                           7.29.1
-wcstombs_s function, K.3.6.5.2                               wmemchr function, 7.28.4.5.8
-wcstoul function, 7.8.2.4, 7.21.6.2, 7.28.2.2,               wmemcmp function, 7.28.4.4.5
-     7.28.4.1.2                                              wmemcpy function, 7.28.4.2.3
-wcstoull function, 7.8.2.4, 7.28.4.1.2                       wmemcpy_s function, K.3.9.2.1.3
-wcstoumax function, 7.8.2.4                                  wmemmove function, 7.28.4.2.4
-wcsxfrm function, 7.28.4.4.4                                 wmemmove_s function, K.3.9.2.1.4
-wctob function, 7.28.6.1.2, 7.29.2.1                         wmemset function, 7.28.4.6.2
-wctomb function, 7.22.7.3, 7.22.8.2, 7.28.6.3                wprintf function, 7.21.1, 7.28.2.9, 7.28.2.11,
-wctomb_s function, K.3.6.4.1                                    K.3.9.1.13
-wctrans function, 7.29.3.2.1, 7.29.3.2.2                     wprintf_s function, K.3.9.1.13
-wctrans_t type, 7.29.1, 7.29.3.2.2                           wscanf function, 7.21.1, 7.28.2.10, 7.28.2.12,
-wctype function, 7.29.2.2.1, 7.29.2.2.2                         7.28.3.10
-wctype.h header, 7.29, 7.30.13                               wscanf_s function, K.3.9.1.12, K.3.9.1.14
-wctype_t type, 7.29.1, 7.29.2.2.2
-weaker, 6.2.8                                                xor macro, 7.9
-WEOF macro, 7.28.1, 7.28.3.1, 7.28.3.3, 7.28.3.6,            xor_eq macro, 7.9
-     7.28.3.7, 7.28.3.8, 7.28.3.9, 7.28.3.10,                xtime type, 7.25.1, 7.25.3.5, 7.25.4.4, 7.25.5.7,
-     7.28.6.1.1, 7.29.1                                          7.25.7.1
-while statement, 6.8.5.1                                     xtime_get function, 7.25.7.1
-white space, 5.1.1.2, 6.4, 6.10, 7.4.1.10,
-     7.29.2.1.10
-white-space characters, 6.4
-wide character, 3.7.3
-  case mapping functions, 7.29.3.1
-     extensible, 7.29.3.2
-  classification functions, 7.29.2.1
-     extensible, 7.29.2.2
-  constant, 6.4.4.4
-  formatted input/output functions, 7.28.2,
-        K.3.9.1
-  input functions, 7.21.1
-  input/output functions, 7.21.1, 7.28.3
-  output functions, 7.21.1
-  single-byte conversion functions, 7.28.6.1
-wide string, 7.1.1
-wide string comparison functions, 7.28.4.4
-wide string concatenation functions, 7.28.4.3,
-     K.3.9.2.2
-wide string copying functions, 7.28.4.2, K.3.9.2.1
-wide string literal, see string literal
-wide string miscellaneous functions, 7.28.4.6,
-     K.3.9.2.4
-wide string numeric conversion functions, 7.8.2.4,
-     7.28.4.1
-wide string search functions, 7.28.4.5, K.3.9.2.3
-wide-oriented stream, 7.21.2
-width, 6.2.6.2
-WINT_MAX macro, 7.20.3
-WINT_MIN macro, 7.20.3
-wint_t type, 7.20.3, 7.21.6.1, 7.28.1, 7.28.2.1,
-
-[page 678] (Contents)
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diff --git a/n1516.txt b/n1516.txt deleted file mode 100644 index 75a1012..0000000 --- a/n1516.txt +++ /dev/null @@ -1,26867 +0,0 @@ -N1516 Committee Draft -- October 4, 2010 ISO/IEC 9899:201x - - - - -INTERNATIONAL STANDARD (C)ISO/IEC ISO/IEC 9899:201x - - - - -Programming languages -- C - - - ABSTRACT - - - - (Cover sheet to be provided by ISO Secretariat.) - -This International Standard specifies the form and establishes the interpretation of -programs expressed in the programming language C. Its purpose is to promote -portability, reliability, maintainability, and efficient execution of C language programs on -a variety of computing systems. - -Clauses are included that detail the C language itself and the contents of the C language -execution library. Annexes summarize aspects of both of them, and enumerate factors -that influence the portability of C programs. - -Although this International Standard is intended to guide knowledgeable C language -programmers as well as implementors of C language translation systems, the document -itself is not designed to serve as a tutorial. - -Recipients of this draft are invited to submit, with their comments, notification of any -relevant patent rights of which they are aware and to provide supporting documentation. - -Changes from the previous draft (N1494) are indicated by ''diff marks'' in the right -margin: deleted text is marked with ''*'', new or changed text with '' ''. - - - - -[page i] - - - -[page ii] - -Contents -Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii -Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii -1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -2. Normative references . . . . . . . . . . . . . . . . . . . . . . . 2 -3. Terms, definitions, and symbols . . . . . . . . . . . . . . . . . . . 3 -4. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . 8 -5. Environment . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5.1 Conceptual models . . . . . . . . . . . . . . . . . . . . . 10 - 5.1.1 Translation environment . . . . . . . . . . . . . . . . 10 - 5.1.2 Execution environments . . . . . . . . . . . . . . . . 12 - 5.2 Environmental considerations . . . . . . . . . . . . . . . . . 22 - 5.2.1 Character sets . . . . . . . . . . . . . . . . . . . . 22 - 5.2.2 Character display semantics . . . . . . . . . . . . . . 24 - 5.2.3 Signals and interrupts . . . . . . . . . . . . . . . . . 25 - 5.2.4 Environmental limits . . . . . . . . . . . . . . . . . 25 -6. Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 - 6.1 Notation . . . . . . . . . . . . . . . . . . . . . . . . . . 35 - 6.2 Concepts . . . . . . . . . . . . . . . . . . . . . . . . . 35 - 6.2.1 Scopes of identifiers . . . . . . . . . . . . . . . . . 35 - 6.2.2 Linkages of identifiers . . . . . . . . . . . . . . . . . 36 - 6.2.3 Name spaces of identifiers . . . . . . . . . . . . . . . 37 - 6.2.4 Storage durations of objects . . . . . . . . . . . . . . 38 - 6.2.5 Types . . . . . . . . . . . . . . . . . . . . . . . 39 - 6.2.6 Representations of types . . . . . . . . . . . . . . . . 44 - 6.2.7 Compatible type and composite type . . . . . . . . . . . 47 - 6.2.8 Alignment of objects . . . . . . . . . . . . . . . . . 48 - 6.3 Conversions . . . . . . . . . . . . . . . . . . . . . . . . 50 - 6.3.1 Arithmetic operands . . . . . . . . . . . . . . . . . 50 - 6.3.2 Other operands . . . . . . . . . . . . . . . . . . . 54 - 6.4 Lexical elements . . . . . . . . . . . . . . . . . . . . . . 57 - 6.4.1 Keywords . . . . . . . . . . . . . . . . . . . . . . 58 - 6.4.2 Identifiers . . . . . . . . . . . . . . . . . . . . . . 59 - 6.4.3 Universal character names . . . . . . . . . . . . . . . 61 - 6.4.4 Constants . . . . . . . . . . . . . . . . . . . . . . 62 - 6.4.5 String literals . . . . . . . . . . . . . . . . . . . . 70 - 6.4.6 Punctuators . . . . . . . . . . . . . . . . . . . . . 72 - 6.4.7 Header names . . . . . . . . . . . . . . . . . . . . 73 - 6.4.8 Preprocessing numbers . . . . . . . . . . . . . . . . 74 - 6.4.9 Comments . . . . . . . . . . . . . . . . . . . . . 75 - - -[page iii] - - 6.5 Expressions . . . . . . . . . . . . . . . . . . . . . . . . 76 - 6.5.1 Primary expressions . . . . . . . . . . . . . . . . . 78 - 6.5.2 Postfix operators . . . . . . . . . . . . . . . . . . . 79 - 6.5.3 Unary operators . . . . . . . . . . . . . . . . . . . 88 - 6.5.4 Cast operators . . . . . . . . . . . . . . . . . . . . 91 - 6.5.5 Multiplicative operators . . . . . . . . . . . . . . . . 92 - 6.5.6 Additive operators . . . . . . . . . . . . . . . . . . 92 - 6.5.7 Bitwise shift operators . . . . . . . . . . . . . . . . . 94 - 6.5.8 Relational operators . . . . . . . . . . . . . . . . . . 95 - 6.5.9 Equality operators . . . . . . . . . . . . . . . . . . 96 - 6.5.10 Bitwise AND operator . . . . . . . . . . . . . . . . . 97 - 6.5.11 Bitwise exclusive OR operator . . . . . . . . . . . . . 98 - 6.5.12 Bitwise inclusive OR operator . . . . . . . . . . . . . . 98 - 6.5.13 Logical AND operator . . . . . . . . . . . . . . . . . 99 - 6.5.14 Logical OR operator . . . . . . . . . . . . . . . . . 99 - 6.5.15 Conditional operator . . . . . . . . . . . . . . . . . 100 - 6.5.16 Assignment operators . . . . . . . . . . . . . . . . . 101 - 6.5.17 Comma operator . . . . . . . . . . . . . . . . . . . 104 - 6.6 Constant expressions . . . . . . . . . . . . . . . . . . . . . 105 - 6.7 Declarations . . . . . . . . . . . . . . . . . . . . . . . . 107 - 6.7.1 Storage-class specifiers . . . . . . . . . . . . . . . . 108 - 6.7.2 Type specifiers . . . . . . . . . . . . . . . . . . . . 109 - 6.7.3 Type qualifiers . . . . . . . . . . . . . . . . . . . . 119 - 6.7.4 Function specifiers . . . . . . . . . . . . . . . . . . 123 - 6.7.5 Alignment specifier . . . . . . . . . . . . . . . . . . 125 - 6.7.6 Declarators . . . . . . . . . . . . . . . . . . . . . 126 - 6.7.7 Type names . . . . . . . . . . . . . . . . . . . . . 134 - 6.7.8 Type definitions . . . . . . . . . . . . . . . . . . . 135 - 6.7.9 Initialization . . . . . . . . . . . . . . . . . . . . 137 - 6.7.10 Static assertions . . . . . . . . . . . . . . . . . . . 143 - 6.8 Statements and blocks . . . . . . . . . . . . . . . . . . . . 144 - 6.8.1 Labeled statements . . . . . . . . . . . . . . . . . . 144 - 6.8.2 Compound statement . . . . . . . . . . . . . . . . . 145 - 6.8.3 Expression and null statements . . . . . . . . . . . . . 145 - 6.8.4 Selection statements . . . . . . . . . . . . . . . . . 146 - 6.8.5 Iteration statements . . . . . . . . . . . . . . . . . . 148 - 6.8.6 Jump statements . . . . . . . . . . . . . . . . . . . 149 - 6.9 External definitions . . . . . . . . . . . . . . . . . . . . . 153 - 6.9.1 Function definitions . . . . . . . . . . . . . . . . . . 154 - 6.9.2 External object definitions . . . . . . . . . . . . . . . 156 - 6.10 Preprocessing directives . . . . . . . . . . . . . . . . . . . 158 - 6.10.1 Conditional inclusion . . . . . . . . . . . . . . . . . 160 - 6.10.2 Source file inclusion . . . . . . . . . . . . . . . . . 162 - 6.10.3 Macro replacement . . . . . . . . . . . . . . . . . . 164 - - -[page iv] - - 6.10.4 Line control . . . . . . . . . . . . . . . . . . . . . 171 - 6.10.5 Error directive . . . . . . . . . . . . . . . . . . . . 172 - 6.10.6 Pragma directive . . . . . . . . . . . . . . . . . . . 172 - 6.10.7 Null directive . . . . . . . . . . . . . . . . . . . . 173 - 6.10.8 Predefined macro names . . . . . . . . . . . . . . . . 173 - 6.10.9 Pragma operator . . . . . . . . . . . . . . . . . . . 175 - 6.11 Future language directions . . . . . . . . . . . . . . . . . . 177 - 6.11.1 Floating types . . . . . . . . . . . . . . . . . . . . 177 - 6.11.2 Linkages of identifiers . . . . . . . . . . . . . . . . . 177 - 6.11.3 External names . . . . . . . . . . . . . . . . . . . 177 - 6.11.4 Character escape sequences . . . . . . . . . . . . . . 177 - 6.11.5 Storage-class specifiers . . . . . . . . . . . . . . . . 177 - 6.11.6 Function declarators . . . . . . . . . . . . . . . . . 177 - 6.11.7 Function definitions . . . . . . . . . . . . . . . . . . 177 - 6.11.8 Pragma directives . . . . . . . . . . . . . . . . . . 177 - 6.11.9 Predefined macro names . . . . . . . . . . . . . . . . 177 -7. Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 - 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 178 - 7.1.1 Definitions of terms . . . . . . . . . . . . . . . . . . 178 - 7.1.2 Standard headers . . . . . . . . . . . . . . . . . . . 179 - 7.1.3 Reserved identifiers . . . . . . . . . . . . . . . . . . 180 - 7.1.4 Use of library functions . . . . . . . . . . . . . . . . 181 - 7.2 Diagnostics . . . . . . . . . . . . . . . . . . 184 - 7.2.1 Program diagnostics . . . . . . . . . . . . . . . . . 184 - 7.3 Complex arithmetic . . . . . . . . . . . . . . 186 - 7.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . 186 - 7.3.2 Conventions . . . . . . . . . . . . . . . . . . . . . 187 - 7.3.3 Branch cuts . . . . . . . . . . . . . . . . . . . . . 187 - 7.3.4 The CX_LIMITED_RANGE pragma . . . . . . . . . . . 187 - 7.3.5 Trigonometric functions . . . . . . . . . . . . . . . . 188 - 7.3.6 Hyperbolic functions . . . . . . . . . . . . . . . . . 190 - 7.3.7 Exponential and logarithmic functions . . . . . . . . . . 192 - 7.3.8 Power and absolute-value functions . . . . . . . . . . . 193 - 7.3.9 Manipulation functions . . . . . . . . . . . . . . . . 194 - 7.4 Character handling . . . . . . . . . . . . . . . . 198 - 7.4.1 Character classification functions . . . . . . . . . . . . 198 - 7.4.2 Character case mapping functions . . . . . . . . . . . . 201 - 7.5 Errors . . . . . . . . . . . . . . . . . . . . . 203 - 7.6 Floating-point environment . . . . . . . . . . . . . 204 - 7.6.1 The FENV_ACCESS pragma . . . . . . . . . . . . . . 206 - 7.6.2 Floating-point exceptions . . . . . . . . . . . . . . . 207 - 7.6.3 Rounding . . . . . . . . . . . . . . . . . . . . . . 210 - 7.6.4 Environment . . . . . . . . . . . . . . . . . . . . 211 - 7.7 Characteristics of floating types . . . . . . . . . . . 214 - -[page v] - - 7.8 Format conversion of integer types . . . . . . . . 215 - 7.8.1 Macros for format specifiers . . . . . . . . . . . . . . 215 - 7.8.2 Functions for greatest-width integer types . . . . . . . . . 216 - 7.9 Alternative spellings . . . . . . . . . . . . . . . 219 - 7.10 Sizes of integer types . . . . . . . . . . . . . . 220 - 7.11 Localization . . . . . . . . . . . . . . . . . . 221 - 7.11.1 Locale control . . . . . . . . . . . . . . . . . . . . 222 - 7.11.2 Numeric formatting convention inquiry . . . . . . . . . . 223 - 7.12 Mathematics . . . . . . . . . . . . . . . . . . . 229 - 7.12.1 Treatment of error conditions . . . . . . . . . . . . . . 231 - 7.12.2 The FP_CONTRACT pragma . . . . . . . . . . . . . . 233 - 7.12.3 Classification macros . . . . . . . . . . . . . . . . . 233 - 7.12.4 Trigonometric functions . . . . . . . . . . . . . . . . 236 - 7.12.5 Hyperbolic functions . . . . . . . . . . . . . . . . . 238 - 7.12.6 Exponential and logarithmic functions . . . . . . . . . . 240 - 7.12.7 Power and absolute-value functions . . . . . . . . . . . 245 - 7.12.8 Error and gamma functions . . . . . . . . . . . . . . . 247 - 7.12.9 Nearest integer functions . . . . . . . . . . . . . . . . 249 - 7.12.10 Remainder functions . . . . . . . . . . . . . . . . . 252 - 7.12.11 Manipulation functions . . . . . . . . . . . . . . . . 253 - 7.12.12 Maximum, minimum, and positive difference functions . . . 255 - 7.12.13 Floating multiply-add . . . . . . . . . . . . . . . . . 256 - 7.12.14 Comparison macros . . . . . . . . . . . . . . . . . . 257 - 7.13 Nonlocal jumps . . . . . . . . . . . . . . . . 260 - 7.13.1 Save calling environment . . . . . . . . . . . . . . . 260 - 7.13.2 Restore calling environment . . . . . . . . . . . . . . 261 - 7.14 Signal handling . . . . . . . . . . . . . . . . . 263 - 7.14.1 Specify signal handling . . . . . . . . . . . . . . . . 264 - 7.14.2 Send signal . . . . . . . . . . . . . . . . . . . . . 265 - 7.15 Alignment . . . . . . . . . . . . . . . . . 266 - 7.16 Variable arguments . . . . . . . . . . . . . . . 267 - 7.16.1 Variable argument list access macros . . . . . . . . . . . 267 - 7.17 Atomics . . . . . . . . . . . . . . . . . . 271 - 7.17.1 Introduction . . . . . . . . . . . . . . . . . . . . . 271 - 7.17.2 Initialization . . . . . . . . . . . . . . . . . . . . 272 - 7.17.3 Order and consistency . . . . . . . . . . . . . . . . . 273 - 7.17.4 Fences . . . . . . . . . . . . . . . . . . . . . . . 276 - 7.17.5 Lock-free property . . . . . . . . . . . . . . . . . . 277 - 7.17.6 Atomic integer and address types . . . . . . . . . . . . 278 - 7.17.7 Operations on atomic types . . . . . . . . . . . . . . . 280 - 7.17.8 Atomic flag type and operations . . . . . . . . . . . . . 283 - 7.18 Boolean type and values . . . . . . . . . . . . 285 - 7.19 Common definitions . . . . . . . . . . . . . . . 286 - 7.20 Integer types . . . . . . . . . . . . . . . . . . 288 - - -[page vi] - - 7.20.1 Integer types . . . . . . . . . . . . . . . . . . . . 288 - 7.20.2 Limits of specified-width integer types . . . . . . . . . . 290 - 7.20.3 Limits of other integer types . . . . . . . . . . . . . . 292 - 7.20.4 Macros for integer constants . . . . . . . . . . . . . . 293 - 7.21 Input/output . . . . . . . . . . . . . . . . . . 295 - 7.21.1 Introduction . . . . . . . . . . . . . . . . . . . . . 295 - 7.21.2 Streams . . . . . . . . . . . . . . . . . . . . . . 297 - 7.21.3 Files . . . . . . . . . . . . . . . . . . . . . . . . 299 - 7.21.4 Operations on files . . . . . . . . . . . . . . . . . . 301 - 7.21.5 File access functions . . . . . . . . . . . . . . . . . 303 - 7.21.6 Formatted input/output functions . . . . . . . . . . . . 308 - 7.21.7 Character input/output functions . . . . . . . . . . . . . 329 - 7.21.8 Direct input/output functions . . . . . . . . . . . . . . 333 - 7.21.9 File positioning functions . . . . . . . . . . . . . . . 334 - 7.21.10 Error-handling functions . . . . . . . . . . . . . . . . 337 - 7.22 General utilities . . . . . . . . . . . . . . . . 339 - 7.22.1 Numeric conversion functions . . . . . . . . . . . . . . 340 - 7.22.2 Pseudo-random sequence generation functions . . . . . . . 345 - 7.22.3 Memory management functions . . . . . . . . . . . . . 346 - 7.22.4 Communication with the environment . . . . . . . . . . 348 - 7.22.5 Searching and sorting utilities . . . . . . . . . . . . . . 352 - 7.22.6 Integer arithmetic functions . . . . . . . . . . . . . . 354 - 7.22.7 Multibyte/wide character conversion functions . . . . . . . 355 - 7.22.8 Multibyte/wide string conversion functions . . . . . . . . 357 - 7.23 String handling . . . . . . . . . . . . . . . . . 359 - 7.23.1 String function conventions . . . . . . . . . . . . . . . 359 - 7.23.2 Copying functions . . . . . . . . . . . . . . . . . . 359 - 7.23.3 Concatenation functions . . . . . . . . . . . . . . . . 361 - 7.23.4 Comparison functions . . . . . . . . . . . . . . . . . 362 - 7.23.5 Search functions . . . . . . . . . . . . . . . . . . . 364 - 7.23.6 Miscellaneous functions . . . . . . . . . . . . . . . . 367 - 7.24 Type-generic math . . . . . . . . . . . . . . . 369 - 7.25 Threads . . . . . . . . . . . . . . . . . . . 372 - 7.25.1 Introduction . . . . . . . . . . . . . . . . . . . . . 372 - 7.25.2 Initialization functions . . . . . . . . . . . . . . . . . 374 - 7.25.3 Condition variable functions . . . . . . . . . . . . . . 374 - 7.25.4 Mutex functions . . . . . . . . . . . . . . . . . . . 376 - 7.25.5 Thread functions . . . . . . . . . . . . . . . . . . . 379 - 7.25.6 Thread-specific storage functions . . . . . . . . . . . . 381 - 7.25.7 Time functions . . . . . . . . . . . . . . . . . . . . 383 - 7.26 Date and time . . . . . . . . . . . . . . . . . . 384 - 7.26.1 Components of time . . . . . . . . . . . . . . . . . 384 - 7.26.2 Time manipulation functions . . . . . . . . . . . . . . 385 - 7.26.3 Time conversion functions . . . . . . . . . . . . . . . 387 - - -[page vii] - - 7.27 Unicode utilities . . . . . . . . . . . . . . . . . 394 - 7.27.1 Restartable multibyte/wide character conversion functions . . 394 - 7.28 Extended multibyte and wide character utilities . . . . . 398 - 7.28.1 Introduction . . . . . . . . . . . . . . . . . . . . . 398 - 7.28.2 Formatted wide character input/output functions . . . . . . 399 - 7.28.3 Wide character input/output functions . . . . . . . . . . 417 - 7.28.4 General wide string utilities . . . . . . . . . . . . . . 421 - 7.28.4.1 Wide string numeric conversion functions . . . . . 422 - 7.28.4.2 Wide string copying functions . . . . . . . . . . 426 - 7.28.4.3 Wide string concatenation functions . . . . . . . 428 - 7.28.4.4 Wide string comparison functions . . . . . . . . 429 - 7.28.4.5 Wide string search functions . . . . . . . . . . 431 - 7.28.4.6 Miscellaneous functions . . . . . . . . . . . . 435 - 7.28.5 Wide character time conversion functions . . . . . . . . . 435 - 7.28.6 Extended multibyte/wide character conversion utilities . . . . 436 - 7.28.6.1 Single-byte/wide character conversion functions . . . 437 - 7.28.6.2 Conversion state functions . . . . . . . . . . . 437 - 7.28.6.3 Restartable multibyte/wide character conversion - functions . . . . . . . . . . . . . . . . . . 438 - 7.28.6.4 Restartable multibyte/wide string conversion - functions . . . . . . . . . . . . . . . . . . 440 - 7.29 Wide character classification and mapping utilities . . . 443 - 7.29.1 Introduction . . . . . . . . . . . . . . . . . . . . . 443 - 7.29.2 Wide character classification utilities . . . . . . . . . . . 444 - 7.29.2.1 Wide character classification functions . . . . . . 444 - 7.29.2.2 Extensible wide character classification - functions . . . . . . . . . . . . . . . . . . 447 - 7.29.3 Wide character case mapping utilities . . . . . . . . . . . 449 - 7.29.3.1 Wide character case mapping functions . . . . . . 449 - 7.29.3.2 Extensible wide character case mapping - functions . . . . . . . . . . . . . . . . . . 449 - 7.30 Future library directions . . . . . . . . . . . . . . . . . . . 451 - 7.30.1 Complex arithmetic . . . . . . . . . . . 451 - 7.30.2 Character handling . . . . . . . . . . . . 451 - 7.30.3 Errors . . . . . . . . . . . . . . . . . 451 - 7.30.4 Format conversion of integer types . . . . 451 - 7.30.5 Localization . . . . . . . . . . . . . . 451 - 7.30.6 Signal handling . . . . . . . . . . . . . 451 - 7.30.7 Boolean type and values . . . . . . . . . 451 - 7.30.8 Integer types . . . . . . . . . . . . . . 451 - 7.30.9 Input/output . . . . . . . . . . . . . . . 452 - 7.30.10 General utilities . . . . . . . . . . . . . 452 - 7.30.11 String handling . . . . . . . . . . . . . 452 - - - -[page viii] - - 7.30.12 Extended multibyte and wide character utilities - . . . . . . . . . . . . . . . . . . . . 452 - 7.30.13 Wide character classification and mapping utilities - . . . . . . . . . . . . . . . . . . . . 452 -Annex A (informative) Language syntax summary . . . . . . . . . . . . 453 - A.1 Lexical grammar . . . . . . . . . . . . . . . . . . . . . . 453 - A.2 Phrase structure grammar . . . . . . . . . . . . . . . . . . . 460 - A.3 Preprocessing directives . . . . . . . . . . . . . . . . . . . 468 -Annex B (informative) Library summary . . . . . . . . . . . . . . . . 470 - B.1 Diagnostics . . . . . . . . . . . . . . . . . . 470 - B.2 Complex . . . . . . . . . . . . . . . . . . . 470 - B.3 Character handling . . . . . . . . . . . . . . . . 472 - B.4 Errors . . . . . . . . . . . . . . . . . . . . . 472 - B.5 Floating-point environment . . . . . . . . . . . . . 472 - B.6 Characteristics of floating types . . . . . . . . . . . 473 - B.7 Format conversion of integer types . . . . . . . . 473 - B.8 Alternative spellings . . . . . . . . . . . . . . . 474 - B.9 Sizes of integer types . . . . . . . . . . . . . . 474 - B.10 Localization . . . . . . . . . . . . . . . . . . 474 - B.11 Mathematics . . . . . . . . . . . . . . . . . . . 474 - B.12 Nonlocal jumps . . . . . . . . . . . . . . . . 479 - B.13 Signal handling . . . . . . . . . . . . . . . . . 479 - B.14 Alignment . . . . . . . . . . . . . . . . . 480 - B.15 Variable arguments . . . . . . . . . . . . . . . 480 - B.16 Atomics . . . . . . . . . . . . . . . . . . 480 - B.17 Boolean type and values . . . . . . . . . . . . 482 - B.18 Common definitions . . . . . . . . . . . . . . . 482 - B.19 Integer types . . . . . . . . . . . . . . . . . . 482 - B.20 Input/output . . . . . . . . . . . . . . . . . . 483 - B.21 General utilities . . . . . . . . . . . . . . . . 486 - B.22 String handling . . . . . . . . . . . . . . . . . 488 - B.23 Type-generic math . . . . . . . . . . . . . . . 490 - B.24 Threads . . . . . . . . . . . . . . . . . . . 490 - B.25 Date and time . . . . . . . . . . . . . . . . . . 491 - B.26 Unicode utilities . . . . . . . . . . . . . . . . . 492 - B.27 Extended multibyte/wide character utilities . . . . . . 492 - B.28 Wide character classification and mapping utilities . . . 497 -Annex C (informative) Sequence points . . . . . . . . . . . . . . . . . 498 -Annex D (normative) Universal character names for identifiers . . . . . . . 499 -Annex E (informative) Implementation limits . . . . . . . . . . . . . . 501 -Annex F (normative) IEC 60559 floating-point arithmetic . . . . . . . . . . 503 - F.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 503 - -[page ix] - - F.2 Types . . . . . . . . . . . . . . . . . . . . . . . . . . . 503 - F.3 Operators and functions . . . . . . . . . . . . . . . . . . . 504 - F.4 Floating to integer conversion . . . . . . . . . . . . . . . . . 506 - F.5 Binary-decimal conversion . . . . . . . . . . . . . . . . . . 506 - F.6 The return statement . . . . . . . . . . . . . . . . . . . . 507 - F.7 Contracted expressions . . . . . . . . . . . . . . . . . . . . 507 - F.8 Floating-point environment . . . . . . . . . . . . . . . . . . 507 - F.9 Optimization . . . . . . . . . . . . . . . . . . . . . . . . 510 - F.10 Mathematics . . . . . . . . . . . . . . . . . . . 513 - F.10.1 Trigonometric functions . . . . . . . . . . . . . . . . 514 - F.10.2 Hyperbolic functions . . . . . . . . . . . . . . . . . 516 - F.10.3 Exponential and logarithmic functions . . . . . . . . . . 516 - F.10.4 Power and absolute value functions . . . . . . . . . . . 519 - F.10.5 Error and gamma functions . . . . . . . . . . . . . . . 521 - F.10.6 Nearest integer functions . . . . . . . . . . . . . . . . 521 - F.10.7 Remainder functions . . . . . . . . . . . . . . . . . 524 - F.10.8 Manipulation functions . . . . . . . . . . . . . . . . 525 - F.10.9 Maximum, minimum, and positive difference functions . . . 525 - F.10.10 Floating multiply-add . . . . . . . . . . . . . . . . . 526 - F.10.11 Comparison macros . . . . . . . . . . . . . . . . . . 526 -Annex G (informative) IEC 60559-compatible complex arithmetic . . . . . . 527 - G.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 527 - G.2 Types . . . . . . . . . . . . . . . . . . . . . . . . . . . 527 - G.3 Conventions . . . . . . . . . . . . . . . . . . . . . . . . 527 - G.4 Conversions . . . . . . . . . . . . . . . . . . . . . . . . 528 - G.4.1 Imaginary types . . . . . . . . . . . . . . . . . . . 528 - G.4.2 Real and imaginary . . . . . . . . . . . . . . . . . . 528 - G.4.3 Imaginary and complex . . . . . . . . . . . . . . . . 528 - G.5 Binary operators . . . . . . . . . . . . . . . . . . . . . . 528 - G.5.1 Multiplicative operators . . . . . . . . . . . . . . . . 529 - G.5.2 Additive operators . . . . . . . . . . . . . . . . . . 532 - G.6 Complex arithmetic . . . . . . . . . . . . . . 532 - G.6.1 Trigonometric functions . . . . . . . . . . . . . . . . 534 - G.6.2 Hyperbolic functions . . . . . . . . . . . . . . . . . 534 - G.6.3 Exponential and logarithmic functions . . . . . . . . . . 538 - G.6.4 Power and absolute-value functions . . . . . . . . . . . 539 - G.7 Type-generic math . . . . . . . . . . . . . . . 540 -Annex H (informative) Language independent arithmetic . . . . . . . . . . 541 - H.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 541 - H.2 Types . . . . . . . . . . . . . . . . . . . . . . . . . . . 541 - H.3 Notification . . . . . . . . . . . . . . . . . . . . . . . . 545 -Annex I (informative) Common warnings . . . . . . . . . . . . . . . . 547 - - -[page x] - -Annex J (informative) Portability issues . . . . . . . . . . . . . . . . . 549 - J.1 Unspecified behavior . . . . . . . . . . . . . . . . . . . . . 549 - J.2 Undefined behavior . . . . . . . . . . . . . . . . . . . . . 552 - J.3 Implementation-defined behavior . . . . . . . . . . . . . . . . 566 - J.4 Locale-specific behavior . . . . . . . . . . . . . . . . . . . 573 - J.5 Common extensions . . . . . . . . . . . . . . . . . . . . . 574 -Annex K (normative) Bounds-checking interfaces . . . . . . . . . . . . . 577 - K.1 Background . . . . . . . . . . . . . . . . . . . . . . . . 577 - K.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 578 - K.3 Library . . . . . . . . . . . . . . . . . . . . . . . . . . 578 - K.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . 578 - K.3.1.1 Standard headers . . . . . . . . . . . . . . . 578 - K.3.1.2 Reserved identifiers . . . . . . . . . . . . . . 579 - K.3.1.3 Use of errno . . . . . . . . . . . . . . . . . 579 - K.3.1.4 Runtime-constraint violations . . . . . . . . . . 579 - K.3.2 Errors . . . . . . . . . . . . . . . . . 580 - K.3.3 Common definitions . . . . . . . . . . . 580 - K.3.4 Integer types . . . . . . . . . . . . . . 580 - K.3.5 Input/output . . . . . . . . . . . . . . . 581 - K.3.5.1 Operations on files . . . . . . . . . . . . . . 581 - K.3.5.2 File access functions . . . . . . . . . . . . . . 583 - K.3.5.3 Formatted input/output functions . . . . . . . . . 586 - K.3.5.4 Character input/output functions . . . . . . . . . 597 - K.3.6 General utilities . . . . . . . . . . . . . 599 - K.3.6.1 Runtime-constraint handling . . . . . . . . . . 599 - K.3.6.2 Communication with the environment . . . . . . . 601 - K.3.6.3 Searching and sorting utilities . . . . . . . . . . 602 - K.3.6.4 Multibyte/wide character conversion functions . . . 605 - K.3.6.5 Multibyte/wide string conversion functions . . . . . 606 - K.3.7 String handling . . . . . . . . . . . . . 609 - K.3.7.1 Copying functions . . . . . . . . . . . . . . 609 - K.3.7.2 Concatenation functions . . . . . . . . . . . . 612 - K.3.7.3 Search functions . . . . . . . . . . . . . . . 615 - K.3.7.4 Miscellaneous functions . . . . . . . . . . . . 616 - K.3.8 Date and time . . . . . . . . . . . . . . . 619 - K.3.8.1 Components of time . . . . . . . . . . . . . . 619 - K.3.8.2 Time conversion functions . . . . . . . . . . . 619 - K.3.9 Extended multibyte and wide character utilities - . . . . . . . . . . . . . . . . . . . . 622 - K.3.9.1 Formatted wide character input/output functions . . . 623 - K.3.9.2 General wide string utilities . . . . . . . . . . . 634 - K.3.9.3 Extended multibyte/wide character conversion - utilities . . . . . . . . . . . . . . . . . . . 642 - - -[page xi] - -Annex L (normative) Analyzability . . . . . . . . . . . . . . . . . . 647 - L.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 647 - L.2 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 647 - L.3 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 648 -Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . 649 -Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653 - - - - -[page xii] - - Foreword -1 ISO (the International Organization for Standardization) and IEC (the International - Electrotechnical Commission) form the specialized system for worldwide - standardization. National bodies that are member of ISO or IEC participate in the - development of International Standards through technical committees established by the - respective organization to deal with particular fields of technical activity. ISO and IEC - technical committees collaborate in fields of mutual interest. Other international - organizations, governmental and non-governmental, in liaison with ISO and IEC, also - take part in the work. -2 International Standards are drafted in accordance with the rules given in the ISO/IEC - Directives, Part 2. This International Standard was drafted in accordance with the fifth - edition (2004). -3 In the field of information technology, ISO and IEC have established a joint technical - committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical - committee are circulated to national bodies for voting. Publication as an International - Standard requires approval by at least 75% of the national bodies casting a vote. -4 Attention is drawn to the possibility that some of the elements of this document may be - the subject of patent rights. ISO and IEC shall not be held responsible for identifying any - or all such patent rights. -5 This International Standard was prepared by Joint Technical Committee ISO/IEC JTC 1, - Information technology, Subcommittee SC 22, Programming languages, their - environments and system software interfaces. The Working Group responsible for this - standard (WG 14) maintains a site on the World Wide Web at http://www.open- - std.org/JTC1/SC22/WG14/ containing additional information relevant to this - standard such as a Rationale for many of the decisions made during its preparation and a - log of Defect Reports and Responses. -6 This third edition cancels and replaces the second edition, ISO/IEC 9899:1999, as - corrected by ISO/IEC 9899:1999/Cor 1:2001, ISO/IEC 9899:1999/Cor 2:2004, and - ISO/IEC 9899:1999/Cor 3:2007. Major changes from the previous edition include: - -- conditional (optional) features (including some that were previously mandatory) - -- support for multiple threads of execution including an improved memory sequencing - model, atomic objects, and thread-local storage ( and - ) - -- additional floating-point characteristic macros () - -- querying and specifying alignment of objects (, ) - -- Unicode characters and strings () (originally specified in - ISO/IEC TR 19769:2004) - -- type-generic expressions - - -[page xiii] - - -- static assertions - -- anonymous structures and unions - -- no-return functions - -- macros to create complex numbers () - -- support for opening files for exclusive access - -- removed the gets function () - -- added the aligned_alloc, at_quick_exit, and quick_exit functions - () - -- (conditional) support for bounds-checking interfaces (originally specified in - ISO/IEC TR 24731-1:2007) - -- (conditional) support for analyzability -7 Major changes in the second edition included: - -- restricted character set support via digraphs and (originally specified - in AMD1) - -- wide character library support in and (originally - specified in AMD1) - -- more precise aliasing rules via effective type - -- restricted pointers - -- variable length arrays - -- flexible array members - -- static and type qualifiers in parameter array declarators - -- complex (and imaginary) support in - -- type-generic math macros in - -- the long long int type and library functions - -- increased minimum translation limits - -- additional floating-point characteristics in - -- remove implicit int - -- reliable integer division - -- universal character names (\u and \U) - -- extended identifiers - -- hexadecimal floating-point constants and %a and %A printf/scanf conversion - specifiers - - - -[page xiv] - --- compound literals --- designated initializers --- // comments --- extended integer types and library functions in and --- remove implicit function declaration --- preprocessor arithmetic done in intmax_t/uintmax_t --- mixed declarations and code --- new block scopes for selection and iteration statements --- integer constant type rules --- integer promotion rules --- macros with a variable number of arguments --- the vscanf family of functions in and --- additional math library functions in --- treatment of error conditions by math library functions (math_errhandling) --- floating-point environment access in --- IEC 60559 (also known as IEC 559 or IEEE arithmetic) support --- trailing comma allowed in enum declaration --- %lf conversion specifier allowed in printf --- inline functions --- the snprintf family of functions in --- boolean type in --- idempotent type qualifiers --- empty macro arguments --- new structure type compatibility rules (tag compatibility) --- additional predefined macro names --- _Pragma preprocessing operator --- standard pragmas --- __func__ predefined identifier --- va_copy macro --- additional strftime conversion specifiers --- LIA compatibility annex - - -[page xv] - - -- deprecate ungetc at the beginning of a binary file - -- remove deprecation of aliased array parameters - -- conversion of array to pointer not limited to lvalues - -- relaxed constraints on aggregate and union initialization - -- relaxed restrictions on portable header names - -- return without expression not permitted in function that returns a value (and vice - versa) -8 Annexes D, F, K, and L form a normative part of this standard; annexes A, B, C, E, G, H, - I, J, the bibliography, and the index are for information only. In accordance with Part 2 of - the ISO/IEC Directives, this foreword, the introduction, notes, footnotes, and examples - are also for information only. - - - - -[page xvi] - - Introduction -1 With the introduction of new devices and extended character sets, new features may be - added to this International Standard. Subclauses in the language and library clauses warn - implementors and programmers of usages which, though valid in themselves, may - conflict with future additions. -2 Certain features are obsolescent, which means that they may be considered for - withdrawal in future revisions of this International Standard. They are retained because - of their widespread use, but their use in new implementations (for implementation - features) or new programs (for language [6.11] or library features [7.30]) is discouraged. -3 This International Standard is divided into four major subdivisions: - -- preliminary elements (clauses 1-4); - -- the characteristics of environments that translate and execute C programs (clause 5); - -- the language syntax, constraints, and semantics (clause 6); - -- the library facilities (clause 7). -4 Examples are provided to illustrate possible forms of the constructions described. - Footnotes are provided to emphasize consequences of the rules described in that - subclause or elsewhere in this International Standard. References are used to refer to - other related subclauses. Recommendations are provided to give advice or guidance to - implementors. Annexes provide additional information and summarize the information - contained in this International Standard. A bibliography lists documents that were - referred to during the preparation of the standard. -5 The language clause (clause 6) is derived from ''The C Reference Manual''. -6 The library clause (clause 7) is based on the 1984 /usr/group Standard. - - - - -[page xvii] - - - -[page xviii] - - - - Programming languages -- C - - - - 1. Scope -1 This International Standard specifies the form and establishes the interpretation of - programs written in the C programming language.1) It specifies - -- the representation of C programs; - -- the syntax and constraints of the C language; - -- the semantic rules for interpreting C programs; - -- the representation of input data to be processed by C programs; - -- the representation of output data produced by C programs; - -- the restrictions and limits imposed by a conforming implementation of C. -2 This International Standard does not specify - -- the mechanism by which C programs are transformed for use by a data-processing - system; - -- the mechanism by which C programs are invoked for use by a data-processing - system; - -- the mechanism by which input data are transformed for use by a C program; - -- the mechanism by which output data are transformed after being produced by a C - program; - -- the size or complexity of a program and its data that will exceed the capacity of any - specific data-processing system or the capacity of a particular processor; - -- all minimal requirements of a data-processing system that is capable of supporting a - conforming implementation. - - - 1) This International Standard is designed to promote the portability of C programs among a variety of - data-processing systems. It is intended for use by implementors and programmers. - -[page 1] - - - 2. Normative references -1 The following referenced documents are indispensable for the application of this - document. For dated references, only the edition cited applies. For undated references, - the latest edition of the referenced document (including any amendments) applies. -2 ISO 31-11:1992, Quantities and units -- Part 11: Mathematical signs and symbols for - use in the physical sciences and technology. -3 ISO/IEC 646, Information technology -- ISO 7-bit coded character set for information - interchange. -4 ISO/IEC 2382-1:1993, Information technology -- Vocabulary -- Part 1: Fundamental - terms. -5 ISO 4217, Codes for the representation of currencies and funds. -6 ISO 8601, Data elements and interchange formats -- Information interchange -- - Representation of dates and times. -7 ISO/IEC 10646 (all parts), Information technology -- Universal Multiple-Octet Coded - Character Set (UCS). -8 IEC 60559:1989, Binary floating-point arithmetic for microprocessor systems (previously - designated IEC 559:1989). - - - - -[page 2] - - - 3. Terms, definitions, and symbols -1 For the purposes of this International Standard, the following definitions apply. Other - terms are defined where they appear in italic type or on the left side of a syntax rule. - Terms explicitly defined in this International Standard are not to be presumed to refer - implicitly to similar terms defined elsewhere. Terms not defined in this International - Standard are to be interpreted according to ISO/IEC 2382-1. Mathematical symbols not - defined in this International Standard are to be interpreted according to ISO 31-11. - 3.1 -1 access - to read or modify the value of an object -2 NOTE 1 Where only one of these two actions is meant, ''read'' or ''modify'' is used. - -3 NOTE 2 ''Modify'' includes the case where the new value being stored is the same as the previous value. - -4 NOTE 3 Expressions that are not evaluated do not access objects. - - 3.2 -1 alignment - requirement that objects of a particular type be located on storage boundaries with - addresses that are particular multiples of a byte address - 3.3 -1 argument - actual argument - actual parameter (deprecated) - expression in the comma-separated list bounded by the parentheses in a function call - expression, or a sequence of preprocessing tokens in the comma-separated list bounded - by the parentheses in a function-like macro invocation - 3.4 -1 behavior - external appearance or action - 3.4.1 -1 implementation-defined behavior - unspecified behavior where each implementation documents how the choice is made -2 EXAMPLE An example of implementation-defined behavior is the propagation of the high-order bit - when a signed integer is shifted right. - - 3.4.2 -1 locale-specific behavior - behavior that depends on local conventions of nationality, culture, and language that each - implementation documents - - -[page 3] - -2 EXAMPLE An example of locale-specific behavior is whether the islower function returns true for - characters other than the 26 lowercase Latin letters. - - 3.4.3 -1 undefined behavior - behavior, upon use of a nonportable or erroneous program construct or of erroneous data, - for which this International Standard imposes no requirements -2 NOTE Possible undefined behavior ranges from ignoring the situation completely with unpredictable - results, to behaving during translation or program execution in a documented manner characteristic of the - environment (with or without the issuance of a diagnostic message), to terminating a translation or - execution (with the issuance of a diagnostic message). - -3 EXAMPLE An example of undefined behavior is the behavior on integer overflow. - - 3.4.4 -1 unspecified behavior - use of an unspecified value, or other behavior where this International Standard provides - two or more possibilities and imposes no further requirements on which is chosen in any - instance -2 EXAMPLE An example of unspecified behavior is the order in which the arguments to a function are - evaluated. - - 3.5 -1 bit - unit of data storage in the execution environment large enough to hold an object that may - have one of two values -2 NOTE It need not be possible to express the address of each individual bit of an object. - - 3.6 -1 byte - addressable unit of data storage large enough to hold any member of the basic character - set of the execution environment -2 NOTE 1 It is possible to express the address of each individual byte of an object uniquely. - -3 NOTE 2 A byte is composed of a contiguous sequence of bits, the number of which is implementation- - defined. The least significant bit is called the low-order bit; the most significant bit is called the high-order - bit. - - 3.7 -1 character - member of a set of elements used for the organization, control, or - representation of data - 3.7.1 -1 character - single-byte character - bit representation that fits in a byte -[page 4] - - 3.7.2 -1 multibyte character - sequence of one or more bytes representing a member of the extended character set of - either the source or the execution environment -2 NOTE The extended character set is a superset of the basic character set. - - 3.7.3 -1 wide character - bit representation that fits in an object of type wchar_t, capable of representing any - character in the current locale - 3.8 -1 constraint - restriction, either syntactic or semantic, by which the exposition of language elements is - to be interpreted - 3.9 -1 correctly rounded result - representation in the result format that is nearest in value, subject to the current rounding - mode, to what the result would be given unlimited range and precision - 3.10 -1 diagnostic message - message belonging to an implementation-defined subset of the implementation's message - output - 3.11 -1 forward reference - reference to a later subclause of this International Standard that contains additional - information relevant to this subclause - 3.12 -1 implementation - particular set of software, running in a particular translation environment under particular - control options, that performs translation of programs for, and supports execution of - functions in, a particular execution environment - 3.13 -1 implementation limit - restriction imposed upon programs by the implementation - 3.14 -1 memory location - either an object of scalar type, or a maximal sequence of adjacent bit-fields all having - nonzero width - -[page 5] - -2 NOTE 1 Two threads of execution can update and access separate memory locations without interfering - with each other. - -3 NOTE 2 A bit-field and an adjacent non-bit-field member are in separate memory locations. The same - applies to two bit-fields, if one is declared inside a nested structure declaration and the other is not, or if the - two are separated by a zero-length bit-field declaration, or if they are separated by a non-bit-field member - declaration. It is not safe to concurrently update two non-atomic bit-fields in the same structure if all - members declared between them are also (non-zero-length) bit-fields, no matter what the sizes of those - intervening bit-fields happen to be. - -4 EXAMPLE A structure declared as - struct { - char a; - int b:5, c:11, :0, d:8; - struct { int ee:8; } e; - } - contains four separate memory locations: The member a, and bit-fields d and e.ee are each separate - memory locations, and can be modified concurrently without interfering with each other. The bit-fields b - and c together constitute the fourth memory location. The bit-fields b and c cannot be concurrently - modified, but b and a, for example, can be. - - 3.15 -1 object - region of data storage in the execution environment, the contents of which can represent - values -2 NOTE When referenced, an object may be interpreted as having a particular type; see 6.3.2.1. - - 3.16 -1 parameter - formal parameter - formal argument (deprecated) - object declared as part of a function declaration or definition that acquires a value on - entry to the function, or an identifier from the comma-separated list bounded by the - parentheses immediately following the macro name in a function-like macro definition - 3.17 -1 recommended practice - specification that is strongly recommended as being in keeping with the intent of the - standard, but that may be impractical for some implementations - 3.18 -1 runtime-constraint - requirement on a program when calling a library function -2 NOTE 1 Despite the similar terms, a runtime-constraint is not a kind of constraint as defined by 3.8, and - need not be diagnosed at translation time. - -3 NOTE 2 Implementations that support the extensions in annex K are required to verify that the runtime- - constraints for a library function are not violated by the program; see K.3.1.4. - -[page 6] - - 3.19 -1 value - precise meaning of the contents of an object when interpreted as having a specific type - 3.19.1 -1 implementation-defined value - unspecified value where each implementation documents how the choice is made - 3.19.2 -1 indeterminate value - either an unspecified value or a trap representation - 3.19.3 -1 unspecified value - valid value of the relevant type where this International Standard imposes no - requirements on which value is chosen in any instance -2 NOTE An unspecified value cannot be a trap representation. - - 3.19.4 -1 trap representation - an object representation that need not represent a value of the object type - 3.19.5 -1 perform a trap - interrupt execution of the program such that no further operations are performed -2 NOTE In this International Standard, when the word ''trap'' is not immediately followed by - ''representation'', this is the intended usage.2) - - 3.20 -1 [^ x^] - ceiling of x: the least integer greater than or equal to x -2 EXAMPLE [^2.4^] is 3, [^-2.4^] is -2. - - 3.21 -1 [_ x_] - floor of x: the greatest integer less than or equal to x -2 EXAMPLE [_2.4_] is 2, [_-2.4_] is -3. - - - - - 2) For example, ''Trapping or stopping (if supported) is disabled...'' (F.8.2). Note that fetching a trap - representation might perform a trap but is not required to (see 6.2.6.1). - -[page 7] - - - 4. Conformance -1 In this International Standard, ''shall'' is to be interpreted as a requirement on an - implementation or on a program; conversely, ''shall not'' is to be interpreted as a - prohibition. -2 If a ''shall'' or ''shall not'' requirement that appears outside of a constraint or runtime- - constraint is violated, the behavior is undefined. Undefined behavior is otherwise - indicated in this International Standard by the words ''undefined behavior'' or by the - omission of any explicit definition of behavior. There is no difference in emphasis among - these three; they all describe ''behavior that is undefined''. -3 A program that is correct in all other aspects, operating on correct data, containing - unspecified behavior shall be a correct program and act in accordance with 5.1.2.3. -4 The implementation shall not successfully translate a preprocessing translation unit - containing a #error preprocessing directive unless it is part of a group skipped by - conditional inclusion. -5 A strictly conforming program shall use only those features of the language and library - specified in this International Standard.3) It shall not produce output dependent on any - unspecified, undefined, or implementation-defined behavior, and shall not exceed any - minimum implementation limit. -6 The two forms of conforming implementation are hosted and freestanding. A conforming - hosted implementation shall accept any strictly conforming program. A conforming - freestanding implementation shall accept any strictly conforming program that does not - use complex types and in which the use of the features specified in the library clause - (clause 7) is confined to the contents of the standard headers , - , , , , , - , and . A conforming implementation may have extensions - (including additional library functions), provided they do not alter the behavior of any - strictly conforming program.4) - - - - 3) A strictly conforming program can use conditional features (see 6.10.8.3) provided the use is guarded - by an appropriate conditional inclusion preprocessing directive using the related macro. For example: - #ifdef __STDC_IEC_559__ /* FE_UPWARD defined */ - /* ... */ - fesetround(FE_UPWARD); - /* ... */ - #endif - - 4) This implies that a conforming implementation reserves no identifiers other than those explicitly - reserved in this International Standard. - -[page 8] - -7 A conforming program is one that is acceptable to a conforming implementation.5) -8 An implementation shall be accompanied by a document that defines all implementation- - defined and locale-specific characteristics and all extensions. - Forward references: conditional inclusion (6.10.1), error directive (6.10.5), - characteristics of floating types (7.7), alternative spellings - (7.9), sizes of integer types (7.10), alignment (7.15), - variable arguments (7.16), boolean type and values - (7.18), common definitions (7.19), integer types (7.20). - - - - - 5) Strictly conforming programs are intended to be maximally portable among conforming - implementations. Conforming programs may depend upon nonportable features of a conforming - implementation. - -[page 9] - - - 5. Environment -1 An implementation translates C source files and executes C programs in two data- - processing-system environments, which will be called the translation environment and - the execution environment in this International Standard. Their characteristics define and - constrain the results of executing conforming C programs constructed according to the - syntactic and semantic rules for conforming implementations. - Forward references: In this clause, only a few of many possible forward references - have been noted. - 5.1 Conceptual models - 5.1.1 Translation environment - 5.1.1.1 Program structure -1 A C program need not all be translated at the same time. The text of the program is kept - in units called source files, (or preprocessing files) in this International Standard. A - source file together with all the headers and source files included via the preprocessing - directive #include is known as a preprocessing translation unit. After preprocessing, a - preprocessing translation unit is called a translation unit. Previously translated translation - units may be preserved individually or in libraries. The separate translation units of a - program communicate by (for example) calls to functions whose identifiers have external - linkage, manipulation of objects whose identifiers have external linkage, or manipulation - of data files. Translation units may be separately translated and then later linked to - produce an executable program. - Forward references: linkages of identifiers (6.2.2), external definitions (6.9), - preprocessing directives (6.10). - 5.1.1.2 Translation phases -1 The precedence among the syntax rules of translation is specified by the following - phases.6) - 1. Physical source file multibyte characters are mapped, in an implementation- - defined manner, to the source character set (introducing new-line characters for - end-of-line indicators) if necessary. Trigraph sequences are replaced by - corresponding single-character internal representations. - - - - 6) Implementations shall behave as if these separate phases occur, even though many are typically folded - together in practice. Source files, translation units, and translated translation units need not - necessarily be stored as files, nor need there be any one-to-one correspondence between these entities - and any external representation. The description is conceptual only, and does not specify any - particular implementation. - -[page 10] - - 2. Each instance of a backslash character (\) immediately followed by a new-line - character is deleted, splicing physical source lines to form logical source lines. - Only the last backslash on any physical source line shall be eligible for being part - of such a splice. A source file that is not empty shall end in a new-line character, - which shall not be immediately preceded by a backslash character before any such - splicing takes place. - 3. The source file is decomposed into preprocessing tokens7) and sequences of - white-space characters (including comments). A source file shall not end in a - partial preprocessing token or in a partial comment. Each comment is replaced by - one space character. New-line characters are retained. Whether each nonempty - sequence of white-space characters other than new-line is retained or replaced by - one space character is implementation-defined. - 4. Preprocessing directives are executed, macro invocations are expanded, and - _Pragma unary operator expressions are executed. If a character sequence that - matches the syntax of a universal character name is produced by token - concatenation (6.10.3.3), the behavior is undefined. A #include preprocessing - directive causes the named header or source file to be processed from phase 1 - through phase 4, recursively. All preprocessing directives are then deleted. - 5. Each source character set member and escape sequence in character constants and - string literals is converted to the corresponding member of the execution character - set; if there is no corresponding member, it is converted to an implementation- - defined member other than the null (wide) character.8) - 6. Adjacent string literal tokens are concatenated. - 7. White-space characters separating tokens are no longer significant. Each - preprocessing token is converted into a token. The resulting tokens are - syntactically and semantically analyzed and translated as a translation unit. - 8. All external object and function references are resolved. Library components are - linked to satisfy external references to functions and objects not defined in the - current translation. All such translator output is collected into a program image - which contains information needed for execution in its execution environment. -Forward references: universal character names (6.4.3), lexical elements (6.4), -preprocessing directives (6.10), trigraph sequences (5.2.1.1), external definitions (6.9). - - - -7) As described in 6.4, the process of dividing a source file's characters into preprocessing tokens is - context-dependent. For example, see the handling of < within a #include preprocessing directive. -8) An implementation need not convert all non-corresponding source characters to the same execution - character. - -[page 11] - - 5.1.1.3 Diagnostics -1 A conforming implementation shall produce at least one diagnostic message (identified in - an implementation-defined manner) if a preprocessing translation unit or translation unit - contains a violation of any syntax rule or constraint, even if the behavior is also explicitly - specified as undefined or implementation-defined. Diagnostic messages need not be - produced in other circumstances.9) -2 EXAMPLE An implementation shall issue a diagnostic for the translation unit: - char i; - int i; - because in those cases where wording in this International Standard describes the behavior for a construct - as being both a constraint error and resulting in undefined behavior, the constraint error shall be diagnosed. - - 5.1.2 Execution environments -1 Two execution environments are defined: freestanding and hosted. In both cases, - program startup occurs when a designated C function is called by the execution - environment. All objects with static storage duration shall be initialized (set to their - initial values) before program startup. The manner and timing of such initialization are - otherwise unspecified. Program termination returns control to the execution - environment. - Forward references: storage durations of objects (6.2.4), initialization (6.7.9). - 5.1.2.1 Freestanding environment -1 In a freestanding environment (in which C program execution may take place without any - benefit of an operating system), the name and type of the function called at program - startup are implementation-defined. Any library facilities available to a freestanding - program, other than the minimal set required by clause 4, are implementation-defined. -2 The effect of program termination in a freestanding environment is implementation- - defined. - 5.1.2.2 Hosted environment -1 A hosted environment need not be provided, but shall conform to the following - specifications if present. - - - - - 9) The intent is that an implementation should identify the nature of, and where possible localize, each - violation. Of course, an implementation is free to produce any number of diagnostics as long as a - valid program is still correctly translated. It may also successfully translate an invalid program. - -[page 12] - - 5.1.2.2.1 Program startup -1 The function called at program startup is named main. The implementation declares no - prototype for this function. It shall be defined with a return type of int and with no - parameters: - int main(void) { /* ... */ } - or with two parameters (referred to here as argc and argv, though any names may be - used, as they are local to the function in which they are declared): - int main(int argc, char *argv[]) { /* ... */ } - or equivalent;10) or in some other implementation-defined manner. -2 If they are declared, the parameters to the main function shall obey the following - constraints: - -- The value of argc shall be nonnegative. - -- argv[argc] shall be a null pointer. - -- If the value of argc is greater than zero, the array members argv[0] through - argv[argc-1] inclusive shall contain pointers to strings, which are given - implementation-defined values by the host environment prior to program startup. The - intent is to supply to the program information determined prior to program startup - from elsewhere in the hosted environment. If the host environment is not capable of - supplying strings with letters in both uppercase and lowercase, the implementation - shall ensure that the strings are received in lowercase. - -- If the value of argc is greater than zero, the string pointed to by argv[0] - represents the program name; argv[0][0] shall be the null character if the - program name is not available from the host environment. If the value of argc is - greater than one, the strings pointed to by argv[1] through argv[argc-1] - represent the program parameters. - -- The parameters argc and argv and the strings pointed to by the argv array shall - be modifiable by the program, and retain their last-stored values between program - startup and program termination. - 5.1.2.2.2 Program execution -1 In a hosted environment, a program may use all the functions, macros, type definitions, - and objects described in the library clause (clause 7). - - - - - 10) Thus, int can be replaced by a typedef name defined as int, or the type of argv can be written as - char ** argv, and so on. - -[page 13] - - 5.1.2.2.3 Program termination -1 If the return type of the main function is a type compatible with int, a return from the - initial call to the main function is equivalent to calling the exit function with the value - returned by the main function as its argument;11) reaching the } that terminates the - main function returns a value of 0. If the return type is not compatible with int, the - termination status returned to the host environment is unspecified. - Forward references: definition of terms (7.1.1), the exit function (7.22.4.4). - 5.1.2.3 Program execution -1 The semantic descriptions in this International Standard describe the behavior of an - abstract machine in which issues of optimization are irrelevant. -2 Accessing a volatile object, modifying an object, modifying a file, or calling a function - that does any of those operations are all side effects,12) which are changes in the state of - the execution environment. Evaluation of an expression in general includes both value - computations and initiation of side effects. Value computation for an lvalue expression - includes determining the identity of the designated object. -3 Sequenced before is an asymmetric, transitive, pair-wise relation between evaluations - executed by a single thread, which induces a partial order among those evaluations. - Given any two evaluations A and B, if A is sequenced before B, then the execution of A - shall precede the execution of B. (Conversely, if A is sequenced before B, then B is - sequenced after A.) If A is not sequenced before or after B, then A and B are - unsequenced. Evaluations A and B are indeterminately sequenced when A is sequenced - either before or after B, but it is unspecified which.13) The presence of a sequence point - between the evaluation of expressions A and B implies that every value computation and - side effect associated with A is sequenced before every value computation and side effect - associated with B. (A summary of the sequence points is given in annex C.) -4 In the abstract machine, all expressions are evaluated as specified by the semantics. An - actual implementation need not evaluate part of an expression if it can deduce that its - value is not used and that no needed side effects are produced (including any caused by - - 11) In accordance with 6.2.4, the lifetimes of objects with automatic storage duration declared in main - will have ended in the former case, even where they would not have in the latter. - 12) The IEC 60559 standard for binary floating-point arithmetic requires certain user-accessible status - flags and control modes. Floating-point operations implicitly set the status flags; modes affect result - values of floating-point operations. Implementations that support such floating-point state are - required to regard changes to it as side effects -- see annex F for details. The floating-point - environment library provides a programming facility for indicating when these side - effects matter, freeing the implementations in other cases. - 13) The executions of unsequenced evaluations can interleave. Indeterminately sequenced evaluations - cannot interleave, but can be executed in any order. - -[page 14] - - calling a function or accessing a volatile object). -5 When the processing of the abstract machine is interrupted by receipt of a signal, the - values of objects that are neither lock-free atomic objects nor of type volatile - sig_atomic_t are unspecified, and the value of any object that is modified by the - handler that is neither a lock-free atomic object nor of type volatile - sig_atomic_t becomes undefined. -6 The least requirements on a conforming implementation are: - -- Accesses to volatile objects are evaluated strictly according to the rules of the abstract - machine. - -- At program termination, all data written into files shall be identical to the result that - execution of the program according to the abstract semantics would have produced. - -- The input and output dynamics of interactive devices shall take place as specified in - 7.21.3. The intent of these requirements is that unbuffered or line-buffered output - appear as soon as possible, to ensure that prompting messages actually appear prior to - a program waiting for input. - This is the observable behavior of the program. -7 What constitutes an interactive device is implementation-defined. -8 More stringent correspondences between abstract and actual semantics may be defined by - each implementation. -9 EXAMPLE 1 An implementation might define a one-to-one correspondence between abstract and actual - semantics: at every sequence point, the values of the actual objects would agree with those specified by the - abstract semantics. The keyword volatile would then be redundant. -10 Alternatively, an implementation might perform various optimizations within each translation unit, such - that the actual semantics would agree with the abstract semantics only when making function calls across - translation unit boundaries. In such an implementation, at the time of each function entry and function - return where the calling function and the called function are in different translation units, the values of all - externally linked objects and of all objects accessible via pointers therein would agree with the abstract - semantics. Furthermore, at the time of each such function entry the values of the parameters of the called - function and of all objects accessible via pointers therein would agree with the abstract semantics. In this - type of implementation, objects referred to by interrupt service routines activated by the signal function - would require explicit specification of volatile storage, as well as other implementation-defined - restrictions. - -11 EXAMPLE 2 In executing the fragment - char c1, c2; - /* ... */ - c1 = c1 + c2; - the ''integer promotions'' require that the abstract machine promote the value of each variable to int size - and then add the two ints and truncate the sum. Provided the addition of two chars can be done without - overflow, or with overflow wrapping silently to produce the correct result, the actual execution need only - produce the same result, possibly omitting the promotions. - -[page 15] - -12 EXAMPLE 3 Similarly, in the fragment - float f1, f2; - double d; - /* ... */ - f1 = f2 * d; - the multiplication may be executed using single-precision arithmetic if the implementation can ascertain - that the result would be the same as if it were executed using double-precision arithmetic (for example, if d - were replaced by the constant 2.0, which has type double). - -13 EXAMPLE 4 Implementations employing wide registers have to take care to honor appropriate - semantics. Values are independent of whether they are represented in a register or in memory. For - example, an implicit spilling of a register is not permitted to alter the value. Also, an explicit store and load - is required to round to the precision of the storage type. In particular, casts and assignments are required to - perform their specified conversion. For the fragment - double d1, d2; - float f; - d1 = f = expression; - d2 = (float) expression; - the values assigned to d1 and d2 are required to have been converted to float. - -14 EXAMPLE 5 Rearrangement for floating-point expressions is often restricted because of limitations in - precision as well as range. The implementation cannot generally apply the mathematical associative rules - for addition or multiplication, nor the distributive rule, because of roundoff error, even in the absence of - overflow and underflow. Likewise, implementations cannot generally replace decimal constants in order to - rearrange expressions. In the following fragment, rearrangements suggested by mathematical rules for real - numbers are often not valid (see F.9). - double x, y, z; - /* ... */ - x = (x * y) * z; // not equivalent to x *= y * z; - z = (x - y) + y ; // not equivalent to z = x; - z = x + x * y; // not equivalent to z = x * (1.0 + y); - y = x / 5.0; // not equivalent to y = x * 0.2; - -15 EXAMPLE 6 To illustrate the grouping behavior of expressions, in the following fragment - int a, b; - /* ... */ - a = a + 32760 + b + 5; - the expression statement behaves exactly the same as - a = (((a + 32760) + b) + 5); - due to the associativity and precedence of these operators. Thus, the result of the sum (a + 32760) is - next added to b, and that result is then added to 5 which results in the value assigned to a. On a machine in - which overflows produce an explicit trap and in which the range of values representable by an int is - [-32768, +32767], the implementation cannot rewrite this expression as - a = ((a + b) + 32765); - since if the values for a and b were, respectively, -32754 and -15, the sum a + b would produce a trap - while the original expression would not; nor can the expression be rewritten either as - - -[page 16] - - a = ((a + 32765) + b); - or - a = (a + (b + 32765)); - since the values for a and b might have been, respectively, 4 and -8 or -17 and 12. However, on a machine - in which overflow silently generates some value and where positive and negative overflows cancel, the - above expression statement can be rewritten by the implementation in any of the above ways because the - same result will occur. - -16 EXAMPLE 7 The grouping of an expression does not completely determine its evaluation. In the - following fragment - #include - int sum; - char *p; - /* ... */ - sum = sum * 10 - '0' + (*p++ = getchar()); - the expression statement is grouped as if it were written as - sum = (((sum * 10) - '0') + ((*(p++)) = (getchar()))); - but the actual increment of p can occur at any time between the previous sequence point and the next - sequence point (the ;), and the call to getchar can occur at any point prior to the need of its returned - value. - - Forward references: expressions (6.5), type qualifiers (6.7.3), statements (6.8), the - signal function (7.14), files (7.21.3). - 5.1.2.4 Multi-threaded executions and data races -1 Under a hosted implementation, a program can have more than one thread of execution - (or thread) running concurrently. The execution of each thread proceeds as defined by - the remainder of this standard. The execution of the entire program consists of an - execution of all of its threads.14) Under a freestanding implementation, it is - implementation-defined whether a program can have more than one thread of execution. -2 The value of an object visible to a thread T at a particular point is the initial value of the - object, a value stored in the object by T , or a value stored in the object by another thread, - according to the rules below. -3 NOTE 1 In some cases, there may instead be undefined behavior. Much of this section is motivated by - the desire to support atomic operations with explicit and detailed visibility constraints. However, it also - implicitly supports a simpler view for more restricted programs. - -4 Two expression evaluations conflict if one of them modifies a memory location and the - other one accesses or modifies the same memory location. - - - - - 14) The execution can usually be viewed as an interleaving of all of the threads. However, some kinds of - atomic operations, for example, allow executions inconsistent with a simple interleaving as described - below. - -[page 17] - -5 The library defines a number of atomic operations (7.17) and operations on mutexes - (7.25.4) that are specially identified as synchronization operations. These operations play - a special role in making assignments in one thread visible to another. A synchronization - operation on one or more memory locations is either an acquire operation, a release - operation, both an acquire and release operation, or a consume operation. A - synchronization operation without an associated memory location is a fence and can be - either an acquire fence, a release fence, or both an acquire and release fence. In addition, - there are relaxed atomic operations, which are not synchronization operations, and - atomic read-modify-write operations, which have special characteristics. -6 NOTE 2 For example, a call that acquires a mutex will perform an acquire operation on the locations - composing the mutex. Correspondingly, a call that releases the same mutex will perform a release - operation on those same locations. Informally, performing a release operation on A forces prior side effects - on other memory locations to become visible to other threads that later perform an acquire or consume - operation on A. We do not include relaxed atomic operations as synchronization operations although, like - synchronization operations, they cannot contribute to data races. - -7 All modifications to a particular atomic object M occur in some particular total order, - called the modification order of M. If A and B are modifications of an atomic object M, - and A happens before B, then A shall precede B in the modification order of M, which is - defined below. -8 NOTE 3 This states that the modification orders must respect the ''happens before'' relation. - -9 NOTE 4 There is a separate order for each atomic object. There is no requirement that these can be - combined into a single total order for all objects. In general this will be impossible since different threads - may observe modifications to different variables in inconsistent orders. - -10 A release sequence on an atomic object M is a maximal contiguous sub-sequence of side - effects in the modification order of M, where the first operation is a release and every - subsequent operation either is performed by the same thread that performed the release or - is an atomic read-modify-write operation. -11 Certain library calls synchronize with other library calls performed by another thread. In - particular, an atomic operation A that performs a release operation on an object M - synchronizes with an atomic operation B that performs an acquire operation on M and - reads a value written by any side effect in the release sequence headed by A. -12 NOTE 5 Except in the specified cases, reading a later value does not necessarily ensure visibility as - described below. Such a requirement would sometimes interfere with efficient implementation. - -13 NOTE 6 The specifications of the synchronization operations define when one reads the value written by - another. For atomic variables, the definition is clear. All operations on a given mutex occur in a single total - order. Each mutex acquisition ''reads the value written'' by the last mutex release. - -14 An evaluation A carries a dependency 15) to an evaluation B if: - - - 15) The ''carries a dependency'' relation is a subset of the ''sequenced before'' relation, and is similarly - strictly intra-thread. - -[page 18] - - -- the value of A is used as an operand of B, unless: - o B is an invocation of the kill_dependency macro, - - o A is the left operand of a && or || operator, - - o A is the left operand of a ? : operator, or - - o A is the left operand of a , operator; - or - -- A writes a scalar object or bit-field M, B reads from M the value written by A, and A - is sequenced before B, or - -- for some evaluation X, A carries a dependency to X and X carries a dependency to B. -15 An evaluation A is dependency-ordered before16) an evaluation B if: - -- A performs a release operation on an atomic object M, and B performs a consume - operation on M and reads a value written by any side effect in the release sequence - headed by A, or - -- for some evaluation X, A is dependency-ordered before X and X carries a - dependency to B. -16 An evaluation A inter-thread happens before an evaluation B if A synchronizes with B, A - is dependency-ordered before B, or, for some evaluation X: - -- A synchronizes with X and X is sequenced before B, - -- A is sequenced before X and X inter-thread happens before B, or - -- A inter-thread happens before X and X inter-thread happens before B. -17 NOTE 7 The ''inter-thread happens before'' relation describes arbitrary concatenations of ''sequenced - before'', ''synchronizes with'', and ''dependency-ordered before'' relationships, with two exceptions. The - first exception is that a concatenation is not permitted to end with ''dependency-ordered before'' followed - by ''sequenced before''. The reason for this limitation is that a consume operation participating in a - ''dependency-ordered before'' relationship provides ordering only with respect to operations to which this - consume operation actually carries a dependency. The reason that this limitation applies only to the end of - such a concatenation is that any subsequent release operation will provide the required ordering for a prior - consume operation. The second exception is that a concatenation is not permitted to consist entirely of - ''sequenced before''. The reasons for this limitation are (1) to permit ''inter-thread happens before'' to be - transitively closed and (2) the ''happens before'' relation, defined below, provides for relationships - consisting entirely of ''sequenced before''. - -18 An evaluation A happens before an evaluation B if A is sequenced before B or A inter- - thread happens before B. - - - - 16) The ''dependency-ordered before'' relation is analogous to the ''synchronizes with'' relation, but uses - release/consume in place of release/acquire. - -[page 19] - -19 A visible side effect A on an object M with respect to a value computation B of M - satisfies the conditions: - -- A happens before B, and - -- there is no other side effect X to M such that A happens before X and X happens - before B. - The value of a non-atomic scalar object M, as determined by evaluation B, shall be the - value stored by the visible side effect A. -20 NOTE 8 If there is ambiguity about which side effect to a non-atomic object is visible, then there is a data - race and the behavior is undefined. - -21 NOTE 9 This states that operations on ordinary variables are not visibly reordered. This is not actually - detectable without data races, but it is necessary to ensure that data races, as defined here, and with suitable - restrictions on the use of atomics, correspond to data races in a simple interleaved (sequentially consistent) - execution. - -22 The visible sequence of side effects on an atomic object M, with respect to a value - computation B of M, is a maximal contiguous sub-sequence of side effects in the - modification order of M, where the first side effect is visible with respect to B, and for - every subsequent side effect, it is not the case that B happens before it. The value of an - atomic object M, as determined by evaluation B, shall be the value stored by some - operation in the visible sequence of M with respect to B. Furthermore, if a value - computation A of an atomic object M happens before a value computation B of M, and - the value computed by A corresponds to the value stored by side effect X, then the value - computed by B shall either equal the value computed by A, or be the value stored by side - effect Y , where Y follows X in the modification order of M. -23 NOTE 10 This effectively disallows compiler reordering of atomic operations to a single object, even if - both operations are ''relaxed'' loads. By doing so, we effectively make the ''cache coherence'' guarantee - provided by most hardware available to C atomic operations. - -24 NOTE 11 The visible sequence depends on the ''happens before'' relation, which in turn depends on the - values observed by loads of atomics, which we are restricting here. The intended reading is that there must - exist an association of atomic loads with modifications they observe that, together with suitably chosen - modification orders and the ''happens before'' relation derived as described above, satisfy the resulting - constraints as imposed here. - -25 The execution of a program contains a data race if it contains two conflicting actions in - different threads, at least one of which is not atomic, and neither happens before the - other. Any such data race results in undefined behavior. -26 NOTE 12 It can be shown that programs that correctly use simple mutexes and - memory_order_seq_cst operations to prevent all data races, and use no other synchronization - operations, behave as though the operations executed by their constituent threads were simply interleaved, - with each value computation of an object being the last value stored in that interleaving. This is normally - referred to as ''sequential consistency''. However, this applies only to data-race-free programs, and data- - race-free programs cannot observe most program transformations that do not change single-threaded - program semantics. In fact, most single-threaded program transformations continue to be allowed, since - any program that behaves differently as a result must contain undefined behavior. - -[page 20] - -27 NOTE 13 Compiler transformations that introduce assignments to a potentially shared memory location - that would not be modified by the abstract machine are generally precluded by this standard, since such an - assignment might overwrite another assignment by a different thread in cases in which an abstract machine - execution would not have encountered a data race. This includes implementations of data member - assignment that overwrite adjacent members in separate memory locations. We also generally preclude - reordering of atomic loads in cases in which the atomics in question may alias, since this may violate the - "visible sequence" rules. - -28 NOTE 14 Transformations that introduce a speculative read of a potentially shared memory location may - not preserve the semantics of the program as defined in this standard, since they potentially introduce a data - race. However, they are typically valid in the context of an optimizing compiler that targets a specific - machine with well-defined semantics for data races. They would be invalid for a hypothetical machine that - is not tolerant of races or provides hardware race detection. - - - - -[page 21] - - 5.2 Environmental considerations - 5.2.1 Character sets -1 Two sets of characters and their associated collating sequences shall be defined: the set in - which source files are written (the source character set), and the set interpreted in the - execution environment (the execution character set). Each set is further divided into a - basic character set, whose contents are given by this subclause, and a set of zero or more - locale-specific members (which are not members of the basic character set) called - extended characters. The combined set is also called the extended character set. The - values of the members of the execution character set are implementation-defined. -2 In a character constant or string literal, members of the execution character set shall be - represented by corresponding members of the source character set or by escape - sequences consisting of the backslash \ followed by one or more characters. A byte with - all bits set to 0, called the null character, shall exist in the basic execution character set; it - is used to terminate a character string. -3 Both the basic source and basic execution character sets shall have the following - members: the 26 uppercase letters of the Latin alphabet - A B C D E F G H I J K L M - N O P Q R S T U V W X Y Z - the 26 lowercase letters of the Latin alphabet - a b c d e f g h i j k l m - n o p q r s t u v w x y z - the 10 decimal digits - 0 1 2 3 4 5 6 7 8 9 - the following 29 graphic characters - ! " # % & ' ( ) * + , - . / : - ; < = > ? [ \ ] ^ _ { | } ~ - the space character, and control characters representing horizontal tab, vertical tab, and - form feed. The representation of each member of the source and execution basic - character sets shall fit in a byte. In both the source and execution basic character sets, the - value of each character after 0 in the above list of decimal digits shall be one greater than - the value of the previous. In source files, there shall be some way of indicating the end of - each line of text; this International Standard treats such an end-of-line indicator as if it - were a single new-line character. In the basic execution character set, there shall be - control characters representing alert, backspace, carriage return, and new line. If any - other characters are encountered in a source file (except in an identifier, a character - constant, a string literal, a header name, a comment, or a preprocessing token that is never - -[page 22] - - converted to a token), the behavior is undefined. -4 A letter is an uppercase letter or a lowercase letter as defined above; in this International - Standard the term does not include other characters that are letters in other alphabets. -5 The universal character name construct provides a way to name other characters. - Forward references: universal character names (6.4.3), character constants (6.4.4.4), - preprocessing directives (6.10), string literals (6.4.5), comments (6.4.9), string (7.1.1). - 5.2.1.1 Trigraph sequences -1 Before any other processing takes place, each occurrence of one of the following - sequences of three characters (called trigraph sequences17)) is replaced with the - corresponding single character. - ??= # ??) ] ??! | - ??( [ ??' ^ ??> } - ??/ \ ??< { ??- ~ - No other trigraph sequences exist. Each ? that does not begin one of the trigraphs listed - above is not changed. -2 EXAMPLE 1 - ??=define arraycheck(a, b) a??(b??) ??!??! b??(a??) - becomes - #define arraycheck(a, b) a[b] || b[a] - -3 EXAMPLE 2 The following source line - printf("Eh???/n"); - becomes (after replacement of the trigraph sequence ??/) - printf("Eh?\n"); - - 5.2.1.2 Multibyte characters -1 The source character set may contain multibyte characters, used to represent members of - the extended character set. The execution character set may also contain multibyte - characters, which need not have the same encoding as for the source character set. For - both character sets, the following shall hold: - -- The basic character set shall be present and each character shall be encoded as a - single byte. - -- The presence, meaning, and representation of any additional members is locale- - specific. - - 17) The trigraph sequences enable the input of characters that are not defined in the Invariant Code Set as - described in ISO/IEC 646, which is a subset of the seven-bit US ASCII code set. - -[page 23] - - -- A multibyte character set may have a state-dependent encoding, wherein each - sequence of multibyte characters begins in an initial shift state and enters other - locale-specific shift states when specific multibyte characters are encountered in the - sequence. While in the initial shift state, all single-byte characters retain their usual - interpretation and do not alter the shift state. The interpretation for subsequent bytes - in the sequence is a function of the current shift state. - -- A byte with all bits zero shall be interpreted as a null character independent of shift - state. Such a byte shall not occur as part of any other multibyte character. -2 For source files, the following shall hold: - -- An identifier, comment, string literal, character constant, or header name shall begin - and end in the initial shift state. - -- An identifier, comment, string literal, character constant, or header name shall consist - of a sequence of valid multibyte characters. - 5.2.2 Character display semantics -1 The active position is that location on a display device where the next character output by - the fputc function would appear. The intent of writing a printing character (as defined - by the isprint function) to a display device is to display a graphic representation of - that character at the active position and then advance the active position to the next - position on the current line. The direction of writing is locale-specific. If the active - position is at the final position of a line (if there is one), the behavior of the display device - is unspecified. -2 Alphabetic escape sequences representing nongraphic characters in the execution - character set are intended to produce actions on display devices as follows: - \a (alert) Produces an audible or visible alert without changing the active position. - \b (backspace) Moves the active position to the previous position on the current line. If - the active position is at the initial position of a line, the behavior of the display - device is unspecified. - \f ( form feed) Moves the active position to the initial position at the start of the next - logical page. - \n (new line) Moves the active position to the initial position of the next line. - \r (carriage return) Moves the active position to the initial position of the current line. - \t (horizontal tab) Moves the active position to the next horizontal tabulation position - on the current line. If the active position is at or past the last defined horizontal - tabulation position, the behavior of the display device is unspecified. - \v (vertical tab) Moves the active position to the initial position of the next vertical - tabulation position. If the active position is at or past the last defined vertical -[page 24] - - tabulation position, the behavior of the display device is unspecified. -3 Each of these escape sequences shall produce a unique implementation-defined value - which can be stored in a single char object. The external representations in a text file - need not be identical to the internal representations, and are outside the scope of this - International Standard. - Forward references: the isprint function (7.4.1.8), the fputc function (7.21.7.3). - 5.2.3 Signals and interrupts -1 Functions shall be implemented such that they may be interrupted at any time by a signal, - or may be called by a signal handler, or both, with no alteration to earlier, but still active, - invocations' control flow (after the interruption), function return values, or objects with - automatic storage duration. All such objects shall be maintained outside the function - image (the instructions that compose the executable representation of a function) on a - per-invocation basis. - 5.2.4 Environmental limits -1 Both the translation and execution environments constrain the implementation of - language translators and libraries. The following summarizes the language-related - environmental limits on a conforming implementation; the library-related limits are - discussed in clause 7. - 5.2.4.1 Translation limits -1 The implementation shall be able to translate and execute at least one program that - contains at least one instance of every one of the following limits:18) - -- 127 nesting levels of blocks - -- 63 nesting levels of conditional inclusion - -- 12 pointer, array, and function declarators (in any combinations) modifying an - arithmetic, structure, union, or void type in a declaration - -- 63 nesting levels of parenthesized declarators within a full declarator - -- 63 nesting levels of parenthesized expressions within a full expression - -- 63 significant initial characters in an internal identifier or a macro name (each - universal character name or extended source character is considered a single - character) - -- 31 significant initial characters in an external identifier (each universal character name - specifying a short identifier of 0000FFFF or less is considered 6 characters, each - - - 18) Implementations should avoid imposing fixed translation limits whenever possible. - -[page 25] - - universal character name specifying a short identifier of 00010000 or more is - considered 10 characters, and each extended source character is considered the same - number of characters as the corresponding universal character name, if any)19) - -- 4095 external identifiers in one translation unit - -- 511 identifiers with block scope declared in one block - -- 4095 macro identifiers simultaneously defined in one preprocessing translation unit - -- 127 parameters in one function definition - -- 127 arguments in one function call - -- 127 parameters in one macro definition - -- 127 arguments in one macro invocation - -- 4095 characters in a logical source line - -- 4095 characters in a string literal (after concatenation) - -- 65535 bytes in an object (in a hosted environment only) - -- 15 nesting levels for #included files - -- 1023 case labels for a switch statement (excluding those for any nested switch - statements) - -- 1023 members in a single structure or union - -- 1023 enumeration constants in a single enumeration - -- 63 levels of nested structure or union definitions in a single struct-declaration-list - 5.2.4.2 Numerical limits -1 An implementation is required to document all the limits specified in this subclause, - which are specified in the headers and . Additional limits are - specified in . - Forward references: integer types (7.20). - 5.2.4.2.1 Sizes of integer types -1 The values given below shall be replaced by constant expressions suitable for use in #if - preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the - following shall be replaced by expressions that have the same type as would an - expression that is an object of the corresponding type converted according to the integer - promotions. Their implementation-defined values shall be equal or greater in magnitude - - - 19) See ''future language directions'' (6.11.3). - -[page 26] - -(absolute value) to those shown, with the same sign. --- number of bits for smallest object that is not a bit-field (byte) - CHAR_BIT 8 --- minimum value for an object of type signed char - SCHAR_MIN -127 // -(27 - 1) --- maximum value for an object of type signed char - SCHAR_MAX +127 // 27 - 1 --- maximum value for an object of type unsigned char - UCHAR_MAX 255 // 28 - 1 --- minimum value for an object of type char - CHAR_MIN see below --- maximum value for an object of type char - CHAR_MAX see below --- maximum number of bytes in a multibyte character, for any supported locale - MB_LEN_MAX 1 --- minimum value for an object of type short int - SHRT_MIN -32767 // -(215 - 1) --- maximum value for an object of type short int - SHRT_MAX +32767 // 215 - 1 --- maximum value for an object of type unsigned short int - USHRT_MAX 65535 // 216 - 1 --- minimum value for an object of type int - INT_MIN -32767 // -(215 - 1) --- maximum value for an object of type int - INT_MAX +32767 // 215 - 1 --- maximum value for an object of type unsigned int - UINT_MAX 65535 // 216 - 1 --- minimum value for an object of type long int - LONG_MIN -2147483647 // -(231 - 1) --- maximum value for an object of type long int - LONG_MAX +2147483647 // 231 - 1 --- maximum value for an object of type unsigned long int - ULONG_MAX 4294967295 // 232 - 1 - - -[page 27] - - -- minimum value for an object of type long long int - LLONG_MIN -9223372036854775807 // -(263 - 1) - -- maximum value for an object of type long long int - LLONG_MAX +9223372036854775807 // 263 - 1 - -- maximum value for an object of type unsigned long long int - ULLONG_MAX 18446744073709551615 // 264 - 1 -2 If the value of an object of type char is treated as a signed integer when used in an - expression, the value of CHAR_MIN shall be the same as that of SCHAR_MIN and the - value of CHAR_MAX shall be the same as that of SCHAR_MAX. Otherwise, the value of - CHAR_MIN shall be 0 and the value of CHAR_MAX shall be the same as that of - UCHAR_MAX.20) The value UCHAR_MAX shall equal 2CHAR_BIT - 1. - Forward references: representations of types (6.2.6), conditional inclusion (6.10.1). - 5.2.4.2.2 Characteristics of floating types -1 The characteristics of floating types are defined in terms of a model that describes a - representation of floating-point numbers and values that provide information about an - implementation's floating-point arithmetic.21) The following parameters are used to - define the model for each floating-point type: - s sign ((+-)1) - b base or radix of exponent representation (an integer > 1) - e exponent (an integer between a minimum emin and a maximum emax ) - p precision (the number of base-b digits in the significand) - fk nonnegative integers less than b (the significand digits) -2 A floating-point number (x) is defined by the following model: - p - x = sb e (Sum) f k b-k , - k=1 - emin <= e <= emax - -3 In addition to normalized floating-point numbers ( f 1 > 0 if x != 0), floating types may be - able to contain other kinds of floating-point numbers, such as subnormal floating-point - numbers (x != 0, e = emin , f 1 = 0) and unnormalized floating-point numbers (x != 0, - e > emin , f 1 = 0), and values that are not floating-point numbers, such as infinities and - NaNs. A NaN is an encoding signifying Not-a-Number. A quiet NaN propagates - through almost every arithmetic operation without raising a floating-point exception; a - signaling NaN generally raises a floating-point exception when occurring as an - - - 20) See 6.2.5. - 21) The floating-point model is intended to clarify the description of each floating-point characteristic and - does not require the floating-point arithmetic of the implementation to be identical. - -[page 28] - - arithmetic operand.22) -4 An implementation may give zero and non-numeric values (such as infinities and NaNs) a - sign or may leave them unsigned. Wherever such values are unsigned, any requirement - in this International Standard to retrieve the sign shall produce an unspecified sign, and - any requirement to set the sign shall be ignored. -5 The minimum range of representable values for a floating type is the most negative finite - floating-point number representable in that type through the most positive finite floating- - point number representable in that type. In addition, if negative infinity is representable - in a type, the range of that type is extended to all negative real numbers; likewise, if - positive infinity is representable in a type, the range of that type is extended to all positive - real numbers. -6 The accuracy of the floating-point operations (+, -, *, /) and of the library functions in - and that return floating-point results is implementation- - defined, as is the accuracy of the conversion between floating-point internal - representations and string representations performed by the library functions in - , , and . The implementation may state that the - accuracy is unknown. -7 All integer values in the header, except FLT_ROUNDS, shall be constant - expressions suitable for use in #if preprocessing directives; all floating values shall be - constant expressions. All except DECIMAL_DIG, FLT_EVAL_METHOD, FLT_RADIX, - and FLT_ROUNDS have separate names for all three floating-point types. The floating- - point model representation is provided for all values except FLT_EVAL_METHOD and - FLT_ROUNDS. -8 The rounding mode for floating-point addition is characterized by the implementation- - defined value of FLT_ROUNDS:23) - -1 indeterminable - 0 toward zero - 1 to nearest - 2 toward positive infinity - 3 toward negative infinity - All other values for FLT_ROUNDS characterize implementation-defined rounding - behavior. - - - 22) IEC 60559:1989 specifies quiet and signaling NaNs. For implementations that do not support - IEC 60559:1989, the terms quiet NaN and signaling NaN are intended to apply to encodings with - similar behavior. - 23) Evaluation of FLT_ROUNDS correctly reflects any execution-time change of rounding mode through - the function fesetround in . - -[page 29] - -9 Except for assignment and cast (which remove all extra range and precision), the values - yielded by operators with floating operands and values subject to the usual arithmetic - conversions and of floating constants are evaluated to a format whose range and precision - may be greater than required by the type. The use of evaluation formats is characterized - by the implementation-defined value of FLT_EVAL_METHOD:24) - -1 indeterminable; - 0 evaluate all operations and constants just to the range and precision of the - type; - 1 evaluate operations and constants of type float and double to the - range and precision of the double type, evaluate long double - operations and constants to the range and precision of the long double - type; - 2 evaluate all operations and constants to the range and precision of the - long double type. - All other negative values for FLT_EVAL_METHOD characterize implementation-defined - behavior. -10 The presence or absence of subnormal numbers is characterized by the implementation- - defined values of FLT_HAS_SUBNORM, DBL_HAS_SUBNORM, and - LDBL_HAS_SUBNORM: - -1 indeterminable25) - 0 absent26) (type does not support subnormal numbers) - 1 present (type does support subnormal numbers) -11 The values given in the following list shall be replaced by constant expressions with - implementation-defined values that are greater or equal in magnitude (absolute value) to - those shown, with the same sign: - -- radix of exponent representation, b - FLT_RADIX 2 - - - - - 24) The evaluation method determines evaluation formats of expressions involving all floating types, not - just real types. For example, if FLT_EVAL_METHOD is 1, then the product of two float - _Complex operands is represented in the double _Complex format, and its parts are evaluated to - double. - 25) Characterization as indeterminable is intended if floating-point operations do not consistently interpret - subnormal representations as zero, nor as nonzero. - 26) Characterization as absent is intended if no floating-point operations produce subnormal results from - non-subnormal inputs, even if the type format includes representations of subnormal numbers. - -[page 30] - --- number of base-FLT_RADIX digits in the floating-point significand, p - FLT_MANT_DIG - DBL_MANT_DIG - LDBL_MANT_DIG --- number of decimal digits, n, such that any floating-point number with p radix b digits - can be rounded to a floating-point number with n decimal digits and back again - without change to the value, - { p log10 b if b is a power of 10 - { - { [^1 + p log10 b^] otherwise - FLT_DECIMAL_DIG 6 - DBL_DECIMAL_DIG 10 - LDBL_DECIMAL_DIG 10 --- number of decimal digits, n, such that any floating-point number in the widest - supported floating type with pmax radix b digits can be rounded to a floating-point - number with n decimal digits and back again without change to the value, - { pmax log10 b if b is a power of 10 - { - { [^1 + pmax log10 b^] otherwise - DECIMAL_DIG 10 --- number of decimal digits, q, such that any floating-point number with q decimal digits - can be rounded into a floating-point number with p radix b digits and back again - without change to the q decimal digits, - { p log10 b if b is a power of 10 - { - { [_( p - 1) log10 b_] otherwise - FLT_DIG 6 - DBL_DIG 10 - LDBL_DIG 10 --- minimum negative integer such that FLT_RADIX raised to one less than that power is - a normalized floating-point number, emin - FLT_MIN_EXP - DBL_MIN_EXP - LDBL_MIN_EXP - - - - -[page 31] - - -- minimum negative integer such that 10 raised to that power is in the range of - normalized floating-point numbers, [^log10 b emin -1 ^] - [ ] - FLT_MIN_10_EXP -37 - DBL_MIN_10_EXP -37 - LDBL_MIN_10_EXP -37 - -- maximum integer such that FLT_RADIX raised to one less than that power is a - representable finite floating-point number, emax - FLT_MAX_EXP - DBL_MAX_EXP - LDBL_MAX_EXP - -- maximum integer such that 10 raised to that power is in the range of representable - finite floating-point numbers, [_log10 ((1 - b- p )b emax )_] - FLT_MAX_10_EXP +37 - DBL_MAX_10_EXP +37 - LDBL_MAX_10_EXP +37 -12 The values given in the following list shall be replaced by constant expressions with - implementation-defined values that are greater than or equal to those shown: - -- maximum representable finite floating-point number, (1 - b- p )b emax - FLT_MAX 1E+37 - DBL_MAX 1E+37 - LDBL_MAX 1E+37 -13 The values given in the following list shall be replaced by constant expressions with - implementation-defined (positive) values that are less than or equal to those shown: - -- the difference between 1 and the least value greater than 1 that is representable in the - given floating point type, b1- p - FLT_EPSILON 1E-5 - DBL_EPSILON 1E-9 - LDBL_EPSILON 1E-9 - -- minimum normalized positive floating-point number, b emin -1 - FLT_MIN 1E-37 - DBL_MIN 1E-37 - LDBL_MIN 1E-37 - - - - -[page 32] - - -- minimum positive floating-point number27) - FLT_TRUE_MIN 1E-37 - DBL_TRUE_MIN 1E-37 - LDBL_TRUE_MIN 1E-37 - Recommended practice -14 Conversion from (at least) double to decimal with DECIMAL_DIG digits and back - should be the identity function. -15 EXAMPLE 1 The following describes an artificial floating-point representation that meets the minimum - requirements of this International Standard, and the appropriate values in a header for type - float: - 6 - x = s16e (Sum) f k 16-k , - k=1 - -31 <= e <= +32 - - FLT_RADIX 16 - FLT_MANT_DIG 6 - FLT_EPSILON 9.53674316E-07F - FLT_DECIMAL_DIG 9 - FLT_DIG 6 - FLT_MIN_EXP -31 - FLT_MIN 2.93873588E-39F - FLT_MIN_10_EXP -38 - FLT_MAX_EXP +32 - FLT_MAX 3.40282347E+38F - FLT_MAX_10_EXP +38 - -16 EXAMPLE 2 The following describes floating-point representations that also meet the requirements for - single-precision and double-precision numbers in IEC 60559,28) and the appropriate values in a - header for types float and double: - 24 - x f = s2e (Sum) f k 2-k , - k=1 - -125 <= e <= +128 - - 53 - x d = s2e (Sum) f k 2-k , - k=1 - -1021 <= e <= +1024 - - FLT_RADIX 2 - DECIMAL_DIG 17 - FLT_MANT_DIG 24 - FLT_EPSILON 1.19209290E-07F // decimal constant - FLT_EPSILON 0X1P-23F // hex constant - FLT_DECIMAL_DIG 9 - - - 27) If the presence or absence of subnormal numbers is indeterminable, then the value is intended to be a - positive number no greater than the minimum normalized positive number for the type. - 28) The floating-point model in that standard sums powers of b from zero, so the values of the exponent - limits are one less than shown here. - -[page 33] - - FLT_DIG 6 - FLT_MIN_EXP -125 - FLT_MIN 1.17549435E-38F // decimal constant - FLT_MIN 0X1P-126F // hex constant - FLT_TRUE_MIN 1.40129846E-45F // decimal constant - FLT_TRUE_MIN 0X1P-149F // hex constant - FLT_HAS_SUBNORM 1 - FLT_MIN_10_EXP -37 - FLT_MAX_EXP +128 - FLT_MAX 3.40282347E+38F // decimal constant - FLT_MAX 0X1.fffffeP127F // hex constant - FLT_MAX_10_EXP +38 - DBL_MANT_DIG 53 - DBL_EPSILON 2.2204460492503131E-16 // decimal constant - DBL_EPSILON 0X1P-52 // hex constant - DBL_DECIMAL_DIG 17 - DBL_DIG 15 - DBL_MIN_EXP -1021 - DBL_MIN 2.2250738585072014E-308 // decimal constant - DBL_MIN 0X1P-1022 // hex constant - DBL_TRUE_MIN 4.9406564584124654E-324 // decimal constant - DBL_TRUE_MIN 0X1P-1074 // hex constant - DBL_HAS_SUBNORM 1 - DBL_MIN_10_EXP -307 - DBL_MAX_EXP +1024 - DBL_MAX 1.7976931348623157E+308 // decimal constant - DBL_MAX 0X1.fffffffffffffP1023 // hex constant - DBL_MAX_10_EXP +308 -If a type wider than double were supported, then DECIMAL_DIG would be greater than 17. For -example, if the widest type were to use the minimal-width IEC 60559 double-extended format (64 bits of -precision), then DECIMAL_DIG would be 21. - -Forward references: conditional inclusion (6.10.1), complex arithmetic - (7.3), extended multibyte and wide character utilities -(7.28), floating-point environment (7.6), general utilities -(7.22), input/output (7.21), mathematics (7.12). - - - - -[page 34] - - - 6. Language - 6.1 Notation -1 In the syntax notation used in this clause, syntactic categories (nonterminals) are - indicated by italic type, and literal words and character set members (terminals) by bold - type. A colon (:) following a nonterminal introduces its definition. Alternative - definitions are listed on separate lines, except when prefaced by the words ''one of''. An - optional symbol is indicated by the subscript ''opt'', so that - { expressionopt } - indicates an optional expression enclosed in braces. -2 When syntactic categories are referred to in the main text, they are not italicized and - words are separated by spaces instead of hyphens. -3 A summary of the language syntax is given in annex A. - 6.2 Concepts - 6.2.1 Scopes of identifiers -1 An identifier can denote an object; a function; a tag or a member of a structure, union, or - enumeration; a typedef name; a label name; a macro name; or a macro parameter. The - same identifier can denote different entities at different points in the program. A member - of an enumeration is called an enumeration constant. Macro names and macro - parameters are not considered further here, because prior to the semantic phase of - program translation any occurrences of macro names in the source file are replaced by the - preprocessing token sequences that constitute their macro definitions. -2 For each different entity that an identifier designates, the identifier is visible (i.e., can be - used) only within a region of program text called its scope. Different entities designated - by the same identifier either have different scopes, or are in different name spaces. There - are four kinds of scopes: function, file, block, and function prototype. (A function - prototype is a declaration of a function that declares the types of its parameters.) -3 A label name is the only kind of identifier that has function scope. It can be used (in a - goto statement) anywhere in the function in which it appears, and is declared implicitly - by its syntactic appearance (followed by a : and a statement). -4 Every other identifier has scope determined by the placement of its declaration (in a - declarator or type specifier). If the declarator or type specifier that declares the identifier - appears outside of any block or list of parameters, the identifier has file scope, which - terminates at the end of the translation unit. If the declarator or type specifier that - declares the identifier appears inside a block or within the list of parameter declarations in - a function definition, the identifier has block scope, which terminates at the end of the - associated block. If the declarator or type specifier that declares the identifier appears - -[page 35] - - within the list of parameter declarations in a function prototype (not part of a function - definition), the identifier has function prototype scope, which terminates at the end of the - function declarator. If an identifier designates two different entities in the same name - space, the scopes might overlap. If so, the scope of one entity (the inner scope) will end - strictly before the scope of the other entity (the outer scope). Within the inner scope, the - identifier designates the entity declared in the inner scope; the entity declared in the outer - scope is hidden (and not visible) within the inner scope. -5 Unless explicitly stated otherwise, where this International Standard uses the term - ''identifier'' to refer to some entity (as opposed to the syntactic construct), it refers to the - entity in the relevant name space whose declaration is visible at the point the identifier - occurs. -6 Two identifiers have the same scope if and only if their scopes terminate at the same - point. -7 Structure, union, and enumeration tags have scope that begins just after the appearance of - the tag in a type specifier that declares the tag. Each enumeration constant has scope that - begins just after the appearance of its defining enumerator in an enumerator list. Any - other identifier has scope that begins just after the completion of its declarator. -8 As a special case, a type name (which is not a declaration of an identifier) is considered to - have a scope that begins just after the place within the type name where the omitted - identifier would appear were it not omitted. - Forward references: declarations (6.7), function calls (6.5.2.2), function definitions - (6.9.1), identifiers (6.4.2), macro replacement (6.10.3), name spaces of identifiers (6.2.3), - source file inclusion (6.10.2), statements (6.8). - 6.2.2 Linkages of identifiers -1 An identifier declared in different scopes or in the same scope more than once can be - made to refer to the same object or function by a process called linkage.29) There are - three kinds of linkage: external, internal, and none. -2 In the set of translation units and libraries that constitutes an entire program, each - declaration of a particular identifier with external linkage denotes the same object or - function. Within one translation unit, each declaration of an identifier with internal - linkage denotes the same object or function. Each declaration of an identifier with no - linkage denotes a unique entity. -3 If the declaration of a file scope identifier for an object or a function contains the storage- - class specifier static, the identifier has internal linkage.30) - - - - 29) There is no linkage between different identifiers. - -[page 36] - -4 For an identifier declared with the storage-class specifier extern in a scope in which a - prior declaration of that identifier is visible,31) if the prior declaration specifies internal or - external linkage, the linkage of the identifier at the later declaration is the same as the - linkage specified at the prior declaration. If no prior declaration is visible, or if the prior - declaration specifies no linkage, then the identifier has external linkage. -5 If the declaration of an identifier for a function has no storage-class specifier, its linkage - is determined exactly as if it were declared with the storage-class specifier extern. If - the declaration of an identifier for an object has file scope and no storage-class specifier, - its linkage is external. -6 The following identifiers have no linkage: an identifier declared to be anything other than - an object or a function; an identifier declared to be a function parameter; a block scope - identifier for an object declared without the storage-class specifier extern. -7 If, within a translation unit, the same identifier appears with both internal and external - linkage, the behavior is undefined. - Forward references: declarations (6.7), expressions (6.5), external definitions (6.9), - statements (6.8). - 6.2.3 Name spaces of identifiers -1 If more than one declaration of a particular identifier is visible at any point in a - translation unit, the syntactic context disambiguates uses that refer to different entities. - Thus, there are separate name spaces for various categories of identifiers, as follows: - -- label names (disambiguated by the syntax of the label declaration and use); - -- the tags of structures, unions, and enumerations (disambiguated by following any32) - of the keywords struct, union, or enum); - -- the members of structures or unions; each structure or union has a separate name - space for its members (disambiguated by the type of the expression used to access the - member via the . or -> operator); - -- all other identifiers, called ordinary identifiers (declared in ordinary declarators or as - enumeration constants). - Forward references: enumeration specifiers (6.7.2.2), labeled statements (6.8.1), - structure and union specifiers (6.7.2.1), structure and union members (6.5.2.3), tags - (6.7.2.3), the goto statement (6.8.6.1). - - 30) A function declaration can contain the storage-class specifier static only if it is at file scope; see - 6.7.1. - 31) As specified in 6.2.1, the later declaration might hide the prior declaration. - 32) There is only one name space for tags even though three are possible. - -[page 37] - - 6.2.4 Storage durations of objects -1 An object has a storage duration that determines its lifetime. There are four storage - durations: static, thread, automatic, and allocated. Allocated storage is described in - 7.22.3. -2 The lifetime of an object is the portion of program execution during which storage is - guaranteed to be reserved for it. An object exists, has a constant address,33) and retains - its last-stored value throughout its lifetime.34) If an object is referred to outside of its - lifetime, the behavior is undefined. The value of a pointer becomes indeterminate when - the object it points to (or just past) reaches the end of its lifetime. -3 An object whose identifier is declared without the storage-class specifier - _Thread_local, and either with external or internal linkage or with the storage-class - specifier static, has static storage duration. Its lifetime is the entire execution of the - program and its stored value is initialized only once, prior to program startup. -4 An object whose identifier is declared with the storage-class specifier _Thread_local - has thread storage duration. Its lifetime is the entire execution of the thread for which it - is created, and its stored value is initialized when the thread is started. There is a distinct - object per thread, and use of the declared name in an expression refers to the object - associated with the thread evaluating the expression. The result of attempting to - indirectly access an object with thread storage duration from a thread other than the one - with which the object is associated is implementation-defined. -5 An object whose identifier is declared with no linkage and without the storage-class - specifier static has automatic storage duration, as do some compound literals. The - result of attempting to indirectly access an object with automatic storage duration from a - thread other than the one with which the object is associated is implementation-defined. -6 For such an object that does not have a variable length array type, its lifetime extends - from entry into the block with which it is associated until execution of that block ends in - any way. (Entering an enclosed block or calling a function suspends, but does not end, - execution of the current block.) If the block is entered recursively, a new instance of the - object is created each time. The initial value of the object is indeterminate. If an - initialization is specified for the object, it is performed each time the declaration or - compound literal is reached in the execution of the block; otherwise, the value becomes - indeterminate each time the declaration is reached. - - - - 33) The term ''constant address'' means that two pointers to the object constructed at possibly different - times will compare equal. The address may be different during two different executions of the same - program. - 34) In the case of a volatile object, the last store need not be explicit in the program. - -[page 38] - -7 For such an object that does have a variable length array type, its lifetime extends from - the declaration of the object until execution of the program leaves the scope of the - declaration.35) If the scope is entered recursively, a new instance of the object is created - each time. The initial value of the object is indeterminate. -8 A non-lvalue expression with structure or union type, where the structure or union - contains a member with array type (including, recursively, members of all contained - structures and unions) refers to an object with automatic storage duration and temporary - lifetime.36) Its lifetime begins when the expression is evaluated and its initial value is the - value of the expression. Its lifetime ends when the evaluation of the containing full - expression or full declarator ends. Any attempt to modify an object with temporary - lifetime results in undefined behavior. - Forward references: array declarators (6.7.6.2), compound literals (6.5.2.5), declarators - (6.7.6), function calls (6.5.2.2), initialization (6.7.9), statements (6.8). - 6.2.5 Types -1 The meaning of a value stored in an object or returned by a function is determined by the - type of the expression used to access it. (An identifier declared to be an object is the - simplest such expression; the type is specified in the declaration of the identifier.) Types - are partitioned into object types (types that describe objects) and function types (types - that describe functions). At various points within a translation unit an object type may be - incomplete (lacking sufficient information to determine the size of objects of that type) or - complete (having sufficient information).37) -2 An object declared as type _Bool is large enough to store the values 0 and 1. -3 An object declared as type char is large enough to store any member of the basic - execution character set. If a member of the basic execution character set is stored in a - char object, its value is guaranteed to be nonnegative. If any other character is stored in - a char object, the resulting value is implementation-defined but shall be within the range - of values that can be represented in that type. -4 There are five standard signed integer types, designated as signed char, short - int, int, long int, and long long int. (These and other types may be - designated in several additional ways, as described in 6.7.2.) There may also be - implementation-defined extended signed integer types.38) The standard and extended - signed integer types are collectively called signed integer types.39) - - 35) Leaving the innermost block containing the declaration, or jumping to a point in that block or an - embedded block prior to the declaration, leaves the scope of the declaration. - 36) The address of such an object is taken implicitly when an array member is accessed. - 37) A type may be incomplete or complete throughout an entire translation unit, or it may change states at - different points within a translation unit. - -[page 39] - -5 An object declared as type signed char occupies the same amount of storage as a - ''plain'' char object. A ''plain'' int object has the natural size suggested by the - architecture of the execution environment (large enough to contain any value in the range - INT_MIN to INT_MAX as defined in the header ). -6 For each of the signed integer types, there is a corresponding (but different) unsigned - integer type (designated with the keyword unsigned) that uses the same amount of - storage (including sign information) and has the same alignment requirements. The type - _Bool and the unsigned integer types that correspond to the standard signed integer - types are the standard unsigned integer types. The unsigned integer types that - correspond to the extended signed integer types are the extended unsigned integer types. - The standard and extended unsigned integer types are collectively called unsigned integer - types.40) -7 The standard signed integer types and standard unsigned integer types are collectively - called the standard integer types, the extended signed integer types and extended - unsigned integer types are collectively called the extended integer types. -8 For any two integer types with the same signedness and different integer conversion rank - (see 6.3.1.1), the range of values of the type with smaller integer conversion rank is a - subrange of the values of the other type. -9 The range of nonnegative values of a signed integer type is a subrange of the - corresponding unsigned integer type, and the representation of the same value in each - type is the same.41) A computation involving unsigned operands can never overflow, - because a result that cannot be represented by the resulting unsigned integer type is - reduced modulo the number that is one greater than the largest value that can be - represented by the resulting type. -10 There are three real floating types, designated as float, double, and long - double.42) The set of values of the type float is a subset of the set of values of the - type double; the set of values of the type double is a subset of the set of values of the - type long double. - - - 38) Implementation-defined keywords shall have the form of an identifier reserved for any use as - described in 7.1.3. - 39) Therefore, any statement in this Standard about signed integer types also applies to the extended - signed integer types. - 40) Therefore, any statement in this Standard about unsigned integer types also applies to the extended - unsigned integer types. - 41) The same representation and alignment requirements are meant to imply interchangeability as - arguments to functions, return values from functions, and members of unions. - 42) See ''future language directions'' (6.11.1). - -[page 40] - -11 There are three complex types, designated as float _Complex, double - _Complex, and long double _Complex.43) (Complex types are a conditional - feature that implementations need not support; see 6.10.8.3.) The real floating and - complex types are collectively called the floating types. -12 For each floating type there is a corresponding real type, which is always a real floating - type. For real floating types, it is the same type. For complex types, it is the type given - by deleting the keyword _Complex from the type name. -13 Each complex type has the same representation and alignment requirements as an array - type containing exactly two elements of the corresponding real type; the first element is - equal to the real part, and the second element to the imaginary part, of the complex - number. -14 The type char, the signed and unsigned integer types, and the floating types are - collectively called the basic types. The basic types are complete object types. Even if the - implementation defines two or more basic types to have the same representation, they are - nevertheless different types.44) -15 The three types char, signed char, and unsigned char are collectively called - the character types. The implementation shall define char to have the same range, - representation, and behavior as either signed char or unsigned char.45) -16 An enumeration comprises a set of named integer constant values. Each distinct - enumeration constitutes a different enumerated type. -17 The type char, the signed and unsigned integer types, and the enumerated types are - collectively called integer types. The integer and real floating types are collectively called - real types. -18 Integer and floating types are collectively called arithmetic types. Each arithmetic type - belongs to one type domain: the real type domain comprises the real types, the complex - type domain comprises the complex types. -19 The void type comprises an empty set of values; it is an incomplete object type that - cannot be completed. - - - - 43) A specification for imaginary types is in informative annex G. - 44) An implementation may define new keywords that provide alternative ways to designate a basic (or - any other) type; this does not violate the requirement that all basic types be different. - Implementation-defined keywords shall have the form of an identifier reserved for any use as - described in 7.1.3. - 45) CHAR_MIN, defined in , will have one of the values 0 or SCHAR_MIN, and this can be - used to distinguish the two options. Irrespective of the choice made, char is a separate type from the - other two and is not compatible with either. - -[page 41] - -20 Any number of derived types can be constructed from the object and function types, as - follows: - -- An array type describes a contiguously allocated nonempty set of objects with a - particular member object type, called the element type. The element type shall be - complete whenever the array type is specified. Array types are characterized by their - element type and by the number of elements in the array. An array type is said to be - derived from its element type, and if its element type is T , the array type is sometimes - called ''array of T ''. The construction of an array type from an element type is called - ''array type derivation''. - -- A structure type describes a sequentially allocated nonempty set of member objects - (and, in certain circumstances, an incomplete array), each of which has an optionally - specified name and possibly distinct type. - -- A union type describes an overlapping nonempty set of member objects, each of - which has an optionally specified name and possibly distinct type. - -- A function type describes a function with specified return type. A function type is - characterized by its return type and the number and types of its parameters. A - function type is said to be derived from its return type, and if its return type is T , the - function type is sometimes called ''function returning T ''. The construction of a - function type from a return type is called ''function type derivation''. - -- A pointer type may be derived from a function type or an object type, called the - referenced type. A pointer type describes an object whose value provides a reference - to an entity of the referenced type. A pointer type derived from the referenced type T - is sometimes called ''pointer to T ''. The construction of a pointer type from a - referenced type is called ''pointer type derivation''. A pointer type is a complete - object type. - These methods of constructing derived types can be applied recursively. -21 Arithmetic types and pointer types are collectively called scalar types. Array and - structure types are collectively called aggregate types.46) -22 An array type of unknown size is an incomplete type. It is completed, for an identifier of - that type, by specifying the size in a later declaration (with internal or external linkage). - A structure or union type of unknown content (as described in 6.7.2.3) is an incomplete - type. It is completed, for all declarations of that type, by declaring the same structure or - union tag with its defining content later in the same scope. - - - - - 46) Note that aggregate type does not include union type because an object with union type can only - contain one member at a time. - -[page 42] - -23 A type has known constant size if the type is not incomplete and is not a variable length - array type. -24 Array, function, and pointer types are collectively called derived declarator types. A - declarator type derivation from a type T is the construction of a derived declarator type - from T by the application of an array-type, a function-type, or a pointer-type derivation to - T. -25 A type is characterized by its type category, which is either the outermost derivation of a - derived type (as noted above in the construction of derived types), or the type itself if the - type consists of no derived types. -26 Any type so far mentioned is an unqualified type. Each unqualified type has several - qualified versions of its type,47) corresponding to the combinations of one, two, or all - three of the const, volatile, and restrict qualifiers. The qualified or unqualified - versions of a type are distinct types that belong to the same type category and have the - same representation and alignment requirements.48) A derived type is not qualified by the - qualifiers (if any) of the type from which it is derived. -27 Further, there is the _Atomic qualifier, which may combine with volatile and - restrict. The size, representation, and alignment of an _Atomic-qualified type need - not be the same as those of the corresponding unqualified type. (Atomic types are a - conditional feature that implementations need not support; see 6.10.8.3.) -28 A pointer to void shall have the same representation and alignment requirements as a - pointer to a character type.48) Similarly, pointers to qualified or unqualified versions of - compatible types shall have the same representation and alignment requirements. All - pointers to structure types shall have the same representation and alignment requirements - as each other. All pointers to union types shall have the same representation and - alignment requirements as each other. Pointers to other types need not have the same - representation or alignment requirements. -29 EXAMPLE 1 The type designated as ''float *'' has type ''pointer to float''. Its type category is - pointer, not a floating type. The const-qualified version of this type is designated as ''float * const'' - whereas the type designated as ''const float *'' is not a qualified type -- its type is ''pointer to const- - qualified float'' and is a pointer to a qualified type. - -30 EXAMPLE 2 The type designated as ''struct tag (*[5])(float)'' has type ''array of pointer to - function returning struct tag''. The array has length five and the function has a single parameter of type - float. Its type category is array. - - Forward references: compatible type and composite type (6.2.7), declarations (6.7). - - - - 47) See 6.7.3 regarding qualified array and function types. - 48) The same representation and alignment requirements are meant to imply interchangeability as - arguments to functions, return values from functions, and members of unions. - -[page 43] - - 6.2.6 Representations of types - 6.2.6.1 General -1 The representations of all types are unspecified except as stated in this subclause. -2 Except for bit-fields, objects are composed of contiguous sequences of one or more bytes, - the number, order, and encoding of which are either explicitly specified or - implementation-defined. -3 Values stored in unsigned bit-fields and objects of type unsigned char shall be - represented using a pure binary notation.49) -4 Values stored in non-bit-field objects of any other object type consist of n x CHAR_BIT - bits, where n is the size of an object of that type, in bytes. The value may be copied into - an object of type unsigned char [n] (e.g., by memcpy); the resulting set of bytes is - called the object representation of the value. Values stored in bit-fields consist of m bits, - where m is the size specified for the bit-field. The object representation is the set of m - bits the bit-field comprises in the addressable storage unit holding it. Two values (other - than NaNs) with the same object representation compare equal, but values that compare - equal may have different object representations. -5 Certain object representations need not represent a value of the object type. If the stored - value of an object has such a representation and is read by an lvalue expression that does - not have character type, the behavior is undefined. If such a representation is produced - by a side effect that modifies all or any part of the object by an lvalue expression that - does not have character type, the behavior is undefined.50) Such a representation is called - a trap representation. -6 When a value is stored in an object of structure or union type, including in a member - object, the bytes of the object representation that correspond to any padding bytes take - unspecified values.51) The value of a structure or union object is never a trap - representation, even though the value of a member of the structure or union object may be - a trap representation. -7 When a value is stored in a member of an object of union type, the bytes of the object - representation that do not correspond to that member but do correspond to other members - - 49) A positional representation for integers that uses the binary digits 0 and 1, in which the values - represented by successive bits are additive, begin with 1, and are multiplied by successive integral - powers of 2, except perhaps the bit with the highest position. (Adapted from the American National - Dictionary for Information Processing Systems.) A byte contains CHAR_BIT bits, and the values of - type unsigned char range from 0 to 2 - CHAR_BIT - - 1. - 50) Thus, an automatic variable can be initialized to a trap representation without causing undefined - behavior, but the value of the variable cannot be used until a proper value is stored in it. - 51) Thus, for example, structure assignment need not copy any padding bits. - -[page 44] - - take unspecified values. -8 Where an operator is applied to a value that has more than one object representation, - which object representation is used shall not affect the value of the result.52) Where a - value is stored in an object using a type that has more than one object representation for - that value, it is unspecified which representation is used, but a trap representation shall - not be generated. -9 Loads and stores of objects with _Atomic-qualified types are done with - memory_order_seq_cst semantics. - Forward references: declarations (6.7), expressions (6.5), lvalues, arrays, and function - designators (6.3.2.1), order and consistency (7.17.3). - 6.2.6.2 Integer types -1 For unsigned integer types other than unsigned char, the bits of the object - representation shall be divided into two groups: value bits and padding bits (there need - not be any of the latter). If there are N value bits, each bit shall represent a different - power of 2 between 1 and 2 N -1 , so that objects of that type shall be capable of - representing values from 0 to 2 N - 1 using a pure binary representation; this shall be - known as the value representation. The values of any padding bits are unspecified.53) -2 For signed integer types, the bits of the object representation shall be divided into three - groups: value bits, padding bits, and the sign bit. There need not be any padding bits; - signed char shall not have any padding bits. There shall be exactly one sign bit. - Each bit that is a value bit shall have the same value as the same bit in the object - representation of the corresponding unsigned type (if there are M value bits in the signed - type and N in the unsigned type, then M <= N ). If the sign bit is zero, it shall not affect - the resulting value. If the sign bit is one, the value shall be modified in one of the - following ways: - -- the corresponding value with sign bit 0 is negated (sign and magnitude); - -- the sign bit has the value -(2 M ) (two's complement); - - - 52) It is possible for objects x and y with the same effective type T to have the same value when they are - accessed as objects of type T, but to have different values in other contexts. In particular, if == is - defined for type T, then x == y does not imply that memcmp(&x, &y, sizeof (T)) == 0. - Furthermore, x == y does not necessarily imply that x and y have the same value; other operations - on values of type T may distinguish between them. - 53) Some combinations of padding bits might generate trap representations, for example, if one padding - bit is a parity bit. Regardless, no arithmetic operation on valid values can generate a trap - representation other than as part of an exceptional condition such as an overflow, and this cannot occur - with unsigned types. All other combinations of padding bits are alternative object representations of - the value specified by the value bits. - -[page 45] - - -- the sign bit has the value -(2 M - 1) (ones' complement). - Which of these applies is implementation-defined, as is whether the value with sign bit 1 - and all value bits zero (for the first two), or with sign bit and all value bits 1 (for ones' - complement), is a trap representation or a normal value. In the case of sign and - magnitude and ones' complement, if this representation is a normal value it is called a - negative zero. -3 If the implementation supports negative zeros, they shall be generated only by: - -- the &, |, ^, ~, <<, and >> operators with operands that produce such a value; - -- the +, -, *, /, and % operators where one operand is a negative zero and the result is - zero; - -- compound assignment operators based on the above cases. - It is unspecified whether these cases actually generate a negative zero or a normal zero, - and whether a negative zero becomes a normal zero when stored in an object. -4 If the implementation does not support negative zeros, the behavior of the &, |, ^, ~, <<, - and >> operators with operands that would produce such a value is undefined. -5 The values of any padding bits are unspecified.54) A valid (non-trap) object representation - of a signed integer type where the sign bit is zero is a valid object representation of the - corresponding unsigned type, and shall represent the same value. For any integer type, - the object representation where all the bits are zero shall be a representation of the value - zero in that type. -6 The precision of an integer type is the number of bits it uses to represent values, - excluding any sign and padding bits. The width of an integer type is the same but - including any sign bit; thus for unsigned integer types the two values are the same, while - for signed integer types the width is one greater than the precision. - - - - - 54) Some combinations of padding bits might generate trap representations, for example, if one padding - bit is a parity bit. Regardless, no arithmetic operation on valid values can generate a trap - representation other than as part of an exceptional condition such as an overflow. All other - combinations of padding bits are alternative object representations of the value specified by the value - bits. - -[page 46] - - 6.2.7 Compatible type and composite type -1 Two types have compatible type if their types are the same. Additional rules for - determining whether two types are compatible are described in 6.7.2 for type specifiers, - in 6.7.3 for type qualifiers, and in 6.7.6 for declarators.55) Moreover, two structure, - union, or enumerated types declared in separate translation units are compatible if their - tags and members satisfy the following requirements: If one is declared with a tag, the - other shall be declared with the same tag. If both are completed anywhere within their - respective translation units, then the following additional requirements apply: there shall - be a one-to-one correspondence between their members such that each pair of - corresponding members are declared with compatible types, and such that if one member - of a corresponding pair is declared with a name, the other member is declared with the - same name. For two structures, corresponding members shall be declared in the same - order. For two structures or unions, corresponding bit-fields shall have the same widths. - For two enumerations, corresponding members shall have the same values. -2 All declarations that refer to the same object or function shall have compatible type; - otherwise, the behavior is undefined. -3 A composite type can be constructed from two types that are compatible; it is a type that - is compatible with both of the two types and satisfies the following conditions: - -- If both types are array types, the following rules are applied: - o If one type is an array of known constant size, the composite type is an array of - that size. - o Otherwise, if one type is a variable length array whose size is specified by an - expression that is not evaluated, the behavior is undefined. - o Otherwise, if one type is a variable length array whose size is specified, the - composite type is a variable length array of that size. - o Otherwise, if one type is a variable length array of unspecified size, the composite - type is a variable length array of unspecified size. - o Otherwise, both types are arrays of unknown size and the composite type is an - array of unknown size. - The element type of the composite type is the composite type of the two element - types. - -- If only one type is a function type with a parameter type list (a function prototype), - the composite type is a function prototype with the parameter type list. - - - - 55) Two types need not be identical to be compatible. - -[page 47] - - -- If both types are function types with parameter type lists, the type of each parameter - in the composite parameter type list is the composite type of the corresponding - parameters. - These rules apply recursively to the types from which the two types are derived. -4 For an identifier with internal or external linkage declared in a scope in which a prior - declaration of that identifier is visible,56) if the prior declaration specifies internal or - external linkage, the type of the identifier at the later declaration becomes the composite - type. - Forward references: array declarators (6.7.6.2). -5 EXAMPLE Given the following two file scope declarations: - int f(int (*)(), double (*)[3]); - int f(int (*)(char *), double (*)[]); - The resulting composite type for the function is: - int f(int (*)(char *), double (*)[3]); - - 6.2.8 Alignment of objects -1 Complete object types have alignment requirements which place restrictions on the - addresses at which objects of that type may be allocated. An alignment is an - implementation-defined integer value representing the number of bytes between - successive addresses at which a given object can be allocated. An object type imposes an - alignment requirement on every object of that type: stricter alignment can be requested - using the _Alignas keyword. -2 A fundamental alignment is represented by an alignment less than or equal to the greatest - alignment supported by the implementation in all contexts, which is equal to - alignof(max_align_t). -3 An extended alignment is represented by an alignment greater than - alignof(max_align_t). It is implementation-defined whether any extended - alignments are supported and the contexts in which they are supported. A type having an - extended alignment requirement is an over-aligned type.57) -4 Alignments are represented as values of the type size_t. Valid alignments include only - those values returned by an alignof expression for fundamental types, plus an - additional implementation-defined set of values, which may be empty. Every valid - alignment value shall be an integral power of two. - - - 56) As specified in 6.2.1, the later declaration might hide the prior declaration. - 57) Every over-aligned type is, or contains, a structure or union type with a member to which an extended - alignment has been applied. - -[page 48] - -5 Alignments have an order from weaker to stronger or stricter alignments. Stricter - alignments have larger alignment values. An address that satisfies an alignment - requirement also satisfies any weaker valid alignment requirement. -6 The alignment requirement of a complete type can be queried using an alignof - expression. The types char, signed char, and unsigned char shall have the - weakest alignment requirement. -7 Comparing alignments is meaningful and provides the obvious results: - -- Two alignments are equal when their numeric values are equal. - -- Two alignments are different when their numeric values are not equal. - -- When an alignment is larger than another it represents a stricter alignment. - - - - -[page 49] - - 6.3 Conversions -1 Several operators convert operand values from one type to another automatically. This - subclause specifies the result required from such an implicit conversion, as well as those - that result from a cast operation (an explicit conversion). The list in 6.3.1.8 summarizes - the conversions performed by most ordinary operators; it is supplemented as required by - the discussion of each operator in 6.5. -2 Conversion of an operand value to a compatible type causes no change to the value or the - representation. - Forward references: cast operators (6.5.4). - 6.3.1 Arithmetic operands - 6.3.1.1 Boolean, characters, and integers -1 Every integer type has an integer conversion rank defined as follows: - -- No two signed integer types shall have the same rank, even if they have the same - representation. - -- The rank of a signed integer type shall be greater than the rank of any signed integer - type with less precision. - -- The rank of long long int shall be greater than the rank of long int, which - shall be greater than the rank of int, which shall be greater than the rank of short - int, which shall be greater than the rank of signed char. - -- The rank of any unsigned integer type shall equal the rank of the corresponding - signed integer type, if any. - -- The rank of any standard integer type shall be greater than the rank of any extended - integer type with the same width. - -- The rank of char shall equal the rank of signed char and unsigned char. - -- The rank of _Bool shall be less than the rank of all other standard integer types. - -- The rank of any enumerated type shall equal the rank of the compatible integer type - (see 6.7.2.2). - -- The rank of any extended signed integer type relative to another extended signed - integer type with the same precision is implementation-defined, but still subject to the - other rules for determining the integer conversion rank. - -- For all integer types T1, T2, and T3, if T1 has greater rank than T2 and T2 has - greater rank than T3, then T1 has greater rank than T3. -2 The following may be used in an expression wherever an int or unsigned int may - be used: - -[page 50] - - -- An object or expression with an integer type (other than int or unsigned int) - whose integer conversion rank is less than or equal to the rank of int and - unsigned int. - -- A bit-field of type _Bool, int, signed int, or unsigned int. - If an int can represent all values of the original type (as restricted by the width, for a - bit-field), the value is converted to an int; otherwise, it is converted to an unsigned - int. These are called the integer promotions.58) All other types are unchanged by the - integer promotions. -3 The integer promotions preserve value including sign. As discussed earlier, whether a - ''plain'' char is treated as signed is implementation-defined. - Forward references: enumeration specifiers (6.7.2.2), structure and union specifiers - (6.7.2.1). - 6.3.1.2 Boolean type -1 When any scalar value is converted to _Bool, the result is 0 if the value compares equal - to 0; otherwise, the result is 1.59) - 6.3.1.3 Signed and unsigned integers -1 When a value with integer type is converted to another integer type other than _Bool, if - the value can be represented by the new type, it is unchanged. -2 Otherwise, if the new type is unsigned, the value is converted by repeatedly adding or - subtracting one more than the maximum value that can be represented in the new type - until the value is in the range of the new type.60) -3 Otherwise, the new type is signed and the value cannot be represented in it; either the - result is implementation-defined or an implementation-defined signal is raised. - 6.3.1.4 Real floating and integer -1 When a finite value of real floating type is converted to an integer type other than _Bool, - the fractional part is discarded (i.e., the value is truncated toward zero). If the value of - the integral part cannot be represented by the integer type, the behavior is undefined.61) - - - 58) The integer promotions are applied only: as part of the usual arithmetic conversions, to certain - argument expressions, to the operands of the unary +, -, and ~ operators, and to both operands of the - shift operators, as specified by their respective subclauses. - 59) NaNs do not compare equal to 0 and thus convert to 1. - 60) The rules describe arithmetic on the mathematical value, not the value of a given type of expression. - 61) The remaindering operation performed when a value of integer type is converted to unsigned type - need not be performed when a value of real floating type is converted to unsigned type. Thus, the - range of portable real floating values is (-1, Utype_MAX+1). - -[page 51] - -2 When a value of integer type is converted to a real floating type, if the value being - converted can be represented exactly in the new type, it is unchanged. If the value being - converted is in the range of values that can be represented but cannot be represented - exactly, the result is either the nearest higher or nearest lower representable value, chosen - in an implementation-defined manner. If the value being converted is outside the range of - values that can be represented, the behavior is undefined. - 6.3.1.5 Real floating types -1 When a float is promoted to double or long double, or a double is promoted - to long double, its value is unchanged (if the source value is represented in the - precision and range of its type). -2 When a double is demoted to float, a long double is demoted to double or - float, or a value being represented in greater precision and range than required by its - semantic type (see 6.3.1.8) is explicitly converted (including to its own type), if the value - being converted can be represented exactly in the new type, it is unchanged. If the value - being converted is in the range of values that can be represented but cannot be - represented exactly, the result is either the nearest higher or nearest lower representable - value, chosen in an implementation-defined manner. If the value being converted is - outside the range of values that can be represented, the behavior is undefined. - 6.3.1.6 Complex types -1 When a value of complex type is converted to another complex type, both the real and - imaginary parts follow the conversion rules for the corresponding real types. - 6.3.1.7 Real and complex -1 When a value of real type is converted to a complex type, the real part of the complex - result value is determined by the rules of conversion to the corresponding real type and - the imaginary part of the complex result value is a positive zero or an unsigned zero. -2 When a value of complex type is converted to a real type, the imaginary part of the - complex value is discarded and the value of the real part is converted according to the - conversion rules for the corresponding real type. - 6.3.1.8 Usual arithmetic conversions -1 Many operators that expect operands of arithmetic type cause conversions and yield result - types in a similar way. The purpose is to determine a common real type for the operands - and result. For the specified operands, each operand is converted, without change of type - domain, to a type whose corresponding real type is the common real type. Unless - explicitly stated otherwise, the common real type is also the corresponding real type of - the result, whose type domain is the type domain of the operands if they are the same, - and complex otherwise. This pattern is called the usual arithmetic conversions: - - -[page 52] - - First, if the corresponding real type of either operand is long double, the other - operand is converted, without change of type domain, to a type whose - corresponding real type is long double. - Otherwise, if the corresponding real type of either operand is double, the other - operand is converted, without change of type domain, to a type whose - corresponding real type is double. - Otherwise, if the corresponding real type of either operand is float, the other - operand is converted, without change of type domain, to a type whose - corresponding real type is float.62) - Otherwise, the integer promotions are performed on both operands. Then the - following rules are applied to the promoted operands: - If both operands have the same type, then no further conversion is needed. - Otherwise, if both operands have signed integer types or both have unsigned - integer types, the operand with the type of lesser integer conversion rank is - converted to the type of the operand with greater rank. - Otherwise, if the operand that has unsigned integer type has rank greater or - equal to the rank of the type of the other operand, then the operand with - signed integer type is converted to the type of the operand with unsigned - integer type. - Otherwise, if the type of the operand with signed integer type can represent - all of the values of the type of the operand with unsigned integer type, then - the operand with unsigned integer type is converted to the type of the - operand with signed integer type. - Otherwise, both operands are converted to the unsigned integer type - corresponding to the type of the operand with signed integer type. -2 The values of floating operands and of the results of floating expressions may be - represented in greater precision and range than that required by the type; the types are not - changed thereby.63) - - - - - 62) For example, addition of a double _Complex and a float entails just the conversion of the - float operand to double (and yields a double _Complex result). - 63) The cast and assignment operators are still required to perform their specified conversions as - described in 6.3.1.4 and 6.3.1.5. - -[page 53] - - 6.3.2 Other operands - 6.3.2.1 Lvalues, arrays, and function designators -1 An lvalue is an expression (with an object type other than void) that potentially - designates an object;64) if an lvalue does not designate an object when it is evaluated, the - behavior is undefined. When an object is said to have a particular type, the type is - specified by the lvalue used to designate the object. A modifiable lvalue is an lvalue that - does not have array type, does not have an incomplete type, does not have a const- - qualified type, and if it is a structure or union, does not have any member (including, - recursively, any member or element of all contained aggregates or unions) with a const- - qualified type. -2 Except when it is the operand of the sizeof operator, the unary & operator, the ++ - operator, the -- operator, or the left operand of the . operator or an assignment operator, - an lvalue that does not have array type is converted to the value stored in the designated - object (and is no longer an lvalue). If the lvalue has qualified type, the value has the - unqualified version of the type of the lvalue; otherwise, the value has the type of the - lvalue. If the lvalue has an incomplete type and does not have array type, the behavior is - undefined. If the lvalue designates an object of automatic storage duration that could - have been declared with the register storage class (never had its address taken), and - that object is uninitialized (not declared with an initializer and no assignment to it has - been performed prior to use), the behavior is undefined. -3 Except when it is the operand of the sizeof operator or the unary & operator, or is a - string literal used to initialize an array, an expression that has type ''array of type'' is - converted to an expression with type ''pointer to type'' that points to the initial element of - the array object and is not an lvalue. If the array object has register storage class, the - behavior is undefined. -4 A function designator is an expression that has function type. Except when it is the - operand of the sizeof operator65) or the unary & operator, a function designator with - type ''function returning type'' is converted to an expression that has type ''pointer to - function returning type''. - Forward references: address and indirection operators (6.5.3.2), assignment operators - - 64) The name ''lvalue'' comes originally from the assignment expression E1 = E2, in which the left - operand E1 is required to be a (modifiable) lvalue. It is perhaps better considered as representing an - object ''locator value''. What is sometimes called ''rvalue'' is in this International Standard described - as the ''value of an expression''. - An obvious example of an lvalue is an identifier of an object. As a further example, if E is a unary - expression that is a pointer to an object, *E is an lvalue that designates the object to which E points. - 65) Because this conversion does not occur, the operand of the sizeof operator remains a function - designator and violates the constraint in 6.5.3.4. - -[page 54] - - (6.5.16), common definitions (7.19), initialization (6.7.9), postfix - increment and decrement operators (6.5.2.4), prefix increment and decrement operators - (6.5.3.1), the sizeof operator (6.5.3.4), structure and union members (6.5.2.3). - 6.3.2.2 void -1 The (nonexistent) value of a void expression (an expression that has type void) shall not - be used in any way, and implicit or explicit conversions (except to void) shall not be - applied to such an expression. If an expression of any other type is evaluated as a void - expression, its value or designator is discarded. (A void expression is evaluated for its - side effects.) - 6.3.2.3 Pointers -1 A pointer to void may be converted to or from a pointer to any object type. A pointer to - any object type may be converted to a pointer to void and back again; the result shall - compare equal to the original pointer. -2 For any qualifier q, a pointer to a non-q-qualified type may be converted to a pointer to - the q-qualified version of the type; the values stored in the original and converted pointers - shall compare equal. -3 An integer constant expression with the value 0, or such an expression cast to type - void *, is called a null pointer constant.66) If a null pointer constant is converted to a - pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal - to a pointer to any object or function. -4 Conversion of a null pointer to another pointer type yields a null pointer of that type. - Any two null pointers shall compare equal. -5 An integer may be converted to any pointer type. Except as previously specified, the - result is implementation-defined, might not be correctly aligned, might not point to an - entity of the referenced type, and might be a trap representation.67) -6 Any pointer type may be converted to an integer type. Except as previously specified, the - result is implementation-defined. If the result cannot be represented in the integer type, - the behavior is undefined. The result need not be in the range of values of any integer - type. -7 A pointer to an object type may be converted to a pointer to a different object type. If the - resulting pointer is not correctly aligned68) for the referenced type, the behavior is - undefined. Otherwise, when converted back again, the result shall compare equal to the - - - 66) The macro NULL is defined in (and other headers) as a null pointer constant; see 7.19. - 67) The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to - be consistent with the addressing structure of the execution environment. - -[page 55] - - original pointer. When a pointer to an object is converted to a pointer to a character type, - the result points to the lowest addressed byte of the object. Successive increments of the - result, up to the size of the object, yield pointers to the remaining bytes of the object. -8 A pointer to a function of one type may be converted to a pointer to a function of another - type and back again; the result shall compare equal to the original pointer. If a converted - pointer is used to call a function whose type is not compatible with the referenced type, - the behavior is undefined. - Forward references: cast operators (6.5.4), equality operators (6.5.9), integer types - capable of holding object pointers (7.20.1.4), simple assignment (6.5.16.1). - - - - - 68) In general, the concept ''correctly aligned'' is transitive: if a pointer to type A is correctly aligned for a - pointer to type B, which in turn is correctly aligned for a pointer to type C, then a pointer to type A is - correctly aligned for a pointer to type C. - -[page 56] - - 6.4 Lexical elements - Syntax -1 token: - keyword - identifier - constant - string-literal - punctuator - preprocessing-token: - header-name - identifier - pp-number - character-constant - string-literal - punctuator - each non-white-space character that cannot be one of the above - Constraints -2 Each preprocessing token that is converted to a token shall have the lexical form of a - keyword, an identifier, a constant, a string literal, or a punctuator. - Semantics -3 A token is the minimal lexical element of the language in translation phases 7 and 8. The - categories of tokens are: keywords, identifiers, constants, string literals, and punctuators. - A preprocessing token is the minimal lexical element of the language in translation - phases 3 through 6. The categories of preprocessing tokens are: header names, - identifiers, preprocessing numbers, character constants, string literals, punctuators, and - single non-white-space characters that do not lexically match the other preprocessing - token categories.69) If a ' or a " character matches the last category, the behavior is - undefined. Preprocessing tokens can be separated by white space; this consists of - comments (described later), or white-space characters (space, horizontal tab, new-line, - vertical tab, and form-feed), or both. As described in 6.10, in certain circumstances - during translation phase 4, white space (or the absence thereof) serves as more than - preprocessing token separation. White space may appear within a preprocessing token - only as part of a header name or between the quotation characters in a character constant - or string literal. - - - - 69) An additional category, placemarkers, is used internally in translation phase 4 (see 6.10.3.3); it cannot - occur in source files. - -[page 57] - -4 If the input stream has been parsed into preprocessing tokens up to a given character, the - next preprocessing token is the longest sequence of characters that could constitute a - preprocessing token. There is one exception to this rule: header name preprocessing - tokens are recognized only within #include preprocessing directives and in - implementation-defined locations within #pragma directives. In such contexts, a - sequence of characters that could be either a header name or a string literal is recognized - as the former. -5 EXAMPLE 1 The program fragment 1Ex is parsed as a preprocessing number token (one that is not a - valid floating or integer constant token), even though a parse as the pair of preprocessing tokens 1 and Ex - might produce a valid expression (for example, if Ex were a macro defined as +1). Similarly, the program - fragment 1E1 is parsed as a preprocessing number (one that is a valid floating constant token), whether or - not E is a macro name. - -6 EXAMPLE 2 The program fragment x+++++y is parsed as x ++ ++ + y, which violates a constraint on - increment operators, even though the parse x ++ + ++ y might yield a correct expression. - - Forward references: character constants (6.4.4.4), comments (6.4.9), expressions (6.5), - floating constants (6.4.4.2), header names (6.4.7), macro replacement (6.10.3), postfix - increment and decrement operators (6.5.2.4), prefix increment and decrement operators - (6.5.3.1), preprocessing directives (6.10), preprocessing numbers (6.4.8), string literals - (6.4.5). - 6.4.1 Keywords - Syntax -1 keyword: one of - alignof goto union - auto if unsigned - break inline void - case int volatile - char long while - const register _Alignas - continue restrict _Atomic - default return _Bool - do short _Complex - double signed _Generic - else sizeof _Imaginary - enum static _Noreturn - extern struct _Static_assert - float switch _Thread_local - for typedef - Semantics -2 The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as - keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for -[page 58] - - specifying imaginary types.70) - 6.4.2 Identifiers - 6.4.2.1 General - Syntax -1 identifier: - identifier-nondigit - identifier identifier-nondigit - identifier digit - identifier-nondigit: - nondigit - universal-character-name - other implementation-defined characters - nondigit: one of - _ a b c d e f g h i j k l m - n o p q r s t u v w x y z - A B C D E F G H I J K L M - N O P Q R S T U V W X Y Z - digit: one of - 0 1 2 3 4 5 6 7 8 9 - Semantics -2 An identifier is a sequence of nondigit characters (including the underscore _, the - lowercase and uppercase Latin letters, and other characters) and digits, which designates - one or more entities as described in 6.2.1. Lowercase and uppercase letters are distinct. - There is no specific limit on the maximum length of an identifier. -3 Each universal character name in an identifier shall designate a character whose encoding - in ISO/IEC 10646 falls into one of the ranges specified in annex D.71) The initial - character shall not be a universal character name designating a digit. An implementation - may allow multibyte characters that are not part of the basic source character set to - appear in identifiers; which characters and their correspondence to universal character - names is implementation-defined. - - - - 70) One possible specification for imaginary types appears in annex G. - 71) On systems in which linkers cannot accept extended characters, an encoding of the universal character - name may be used in forming valid external identifiers. For example, some otherwise unused - character or sequence of characters may be used to encode the \u in a universal character name. - Extended characters may produce a long external identifier. - -[page 59] - -4 When preprocessing tokens are converted to tokens during translation phase 7, if a - preprocessing token could be converted to either a keyword or an identifier, it is converted - to a keyword. - Implementation limits -5 As discussed in 5.2.4.1, an implementation may limit the number of significant initial - characters in an identifier; the limit for an external name (an identifier that has external - linkage) may be more restrictive than that for an internal name (a macro name or an - identifier that does not have external linkage). The number of significant characters in an - identifier is implementation-defined. -6 Any identifiers that differ in a significant character are different identifiers. If two - identifiers differ only in nonsignificant characters, the behavior is undefined. - Forward references: universal character names (6.4.3), macro replacement (6.10.3). - 6.4.2.2 Predefined identifiers - Semantics -1 The identifier __func__ shall be implicitly declared by the translator as if, - immediately following the opening brace of each function definition, the declaration - static const char __func__[] = "function-name"; - appeared, where function-name is the name of the lexically-enclosing function.72) -2 This name is encoded as if the implicit declaration had been written in the source - character set and then translated into the execution character set as indicated in translation - phase 5. -3 EXAMPLE Consider the code fragment: - #include - void myfunc(void) - { - printf("%s\n", __func__); - /* ... */ - } - Each time the function is called, it will print to the standard output stream: - myfunc - - Forward references: function definitions (6.9.1). - - - - - 72) Since the name __func__ is reserved for any use by the implementation (7.1.3), if any other - identifier is explicitly declared using the name __func__, the behavior is undefined. - -[page 60] - - 6.4.3 Universal character names - Syntax -1 universal-character-name: - \u hex-quad - \U hex-quad hex-quad - hex-quad: - hexadecimal-digit hexadecimal-digit - hexadecimal-digit hexadecimal-digit - Constraints -2 A universal character name shall not specify a character whose short identifier is less than - 00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through - DFFF inclusive.73) - Description -3 Universal character names may be used in identifiers, character constants, and string - literals to designate characters that are not in the basic character set. - Semantics -4 The universal character name \Unnnnnnnn designates the character whose eight-digit - short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.74) Similarly, the universal - character name \unnnn designates the character whose four-digit short identifier is nnnn - (and whose eight-digit short identifier is 0000nnnn). - - - - - 73) The disallowed characters are the characters in the basic character set and the code positions reserved - by ISO/IEC 10646 for control characters, the character DELETE, and the S-zone (reserved for use by - UTF-16). - - 74) Short identifiers for characters were first specified in ISO/IEC 10646-1/AMD9:1997. - -[page 61] - - 6.4.4 Constants - Syntax -1 constant: - integer-constant - floating-constant - enumeration-constant - character-constant - Constraints -2 Each constant shall have a type and the value of a constant shall be in the range of - representable values for its type. - Semantics -3 Each constant has a type, determined by its form and value, as detailed later. - 6.4.4.1 Integer constants - Syntax -1 integer-constant: - decimal-constant integer-suffixopt - octal-constant integer-suffixopt - hexadecimal-constant integer-suffixopt - decimal-constant: - nonzero-digit - decimal-constant digit - octal-constant: - 0 - octal-constant octal-digit - hexadecimal-constant: - hexadecimal-prefix hexadecimal-digit - hexadecimal-constant hexadecimal-digit - hexadecimal-prefix: one of - 0x 0X - nonzero-digit: one of - 1 2 3 4 5 6 7 8 9 - octal-digit: one of - 0 1 2 3 4 5 6 7 - - - - -[page 62] - - hexadecimal-digit: one of - 0 1 2 3 4 5 6 7 8 9 - a b c d e f - A B C D E F - integer-suffix: - unsigned-suffix long-suffixopt - unsigned-suffix long-long-suffix - long-suffix unsigned-suffixopt - long-long-suffix unsigned-suffixopt - unsigned-suffix: one of - u U - long-suffix: one of - l L - long-long-suffix: one of - ll LL - Description -2 An integer constant begins with a digit, but has no period or exponent part. It may have a - prefix that specifies its base and a suffix that specifies its type. -3 A decimal constant begins with a nonzero digit and consists of a sequence of decimal - digits. An octal constant consists of the prefix 0 optionally followed by a sequence of the - digits 0 through 7 only. A hexadecimal constant consists of the prefix 0x or 0X followed - by a sequence of the decimal digits and the letters a (or A) through f (or F) with values - 10 through 15 respectively. - Semantics -4 The value of a decimal constant is computed base 10; that of an octal constant, base 8; - that of a hexadecimal constant, base 16. The lexically first digit is the most significant. -5 The type of an integer constant is the first of the corresponding list in which its value can - be represented. - - - - -[page 63] - - Octal or Hexadecimal - Suffix Decimal Constant Constant - - none int int - long int unsigned int - long long int long int - unsigned long int - long long int - unsigned long long int - - u or U unsigned int unsigned int - unsigned long int unsigned long int - unsigned long long int unsigned long long int - - l or L long int long int - long long int unsigned long int - long long int - unsigned long long int - - Both u or U unsigned long int unsigned long int - and l or L unsigned long long int unsigned long long int - - ll or LL long long int long long int - unsigned long long int - - Both u or U unsigned long long int unsigned long long int - and ll or LL -6 If an integer constant cannot be represented by any type in its list, it may have an - extended integer type, if the extended integer type can represent its value. If all of the - types in the list for the constant are signed, the extended integer type shall be signed. If - all of the types in the list for the constant are unsigned, the extended integer type shall be - unsigned. If the list contains both signed and unsigned types, the extended integer type - may be signed or unsigned. If an integer constant cannot be represented by any type in - its list and has no extended integer type, then the integer constant has no type. - - - - -[page 64] - - 6.4.4.2 Floating constants - Syntax -1 floating-constant: - decimal-floating-constant - hexadecimal-floating-constant - decimal-floating-constant: - fractional-constant exponent-partopt floating-suffixopt - digit-sequence exponent-part floating-suffixopt - hexadecimal-floating-constant: - hexadecimal-prefix hexadecimal-fractional-constant - binary-exponent-part floating-suffixopt - hexadecimal-prefix hexadecimal-digit-sequence - binary-exponent-part floating-suffixopt - fractional-constant: - digit-sequenceopt . digit-sequence - digit-sequence . - exponent-part: - e signopt digit-sequence - E signopt digit-sequence - sign: one of - + - - digit-sequence: - digit - digit-sequence digit - hexadecimal-fractional-constant: - hexadecimal-digit-sequenceopt . - hexadecimal-digit-sequence - hexadecimal-digit-sequence . - binary-exponent-part: - p signopt digit-sequence - P signopt digit-sequence - hexadecimal-digit-sequence: - hexadecimal-digit - hexadecimal-digit-sequence hexadecimal-digit - floating-suffix: one of - f l F L - -[page 65] - - Description -2 A floating constant has a significand part that may be followed by an exponent part and a - suffix that specifies its type. The components of the significand part may include a digit - sequence representing the whole-number part, followed by a period (.), followed by a - digit sequence representing the fraction part. The components of the exponent part are an - e, E, p, or P followed by an exponent consisting of an optionally signed digit sequence. - Either the whole-number part or the fraction part has to be present; for decimal floating - constants, either the period or the exponent part has to be present. - Semantics -3 The significand part is interpreted as a (decimal or hexadecimal) rational number; the - digit sequence in the exponent part is interpreted as a decimal integer. For decimal - floating constants, the exponent indicates the power of 10 by which the significand part is - to be scaled. For hexadecimal floating constants, the exponent indicates the power of 2 - by which the significand part is to be scaled. For decimal floating constants, and also for - hexadecimal floating constants when FLT_RADIX is not a power of 2, the result is either - the nearest representable value, or the larger or smaller representable value immediately - adjacent to the nearest representable value, chosen in an implementation-defined manner. - For hexadecimal floating constants when FLT_RADIX is a power of 2, the result is - correctly rounded. -4 An unsuffixed floating constant has type double. If suffixed by the letter f or F, it has - type float. If suffixed by the letter l or L, it has type long double. -5 Floating constants are converted to internal format as if at translation-time. The - conversion of a floating constant shall not raise an exceptional condition or a floating- - point exception at execution time. - Recommended practice -6 The implementation should produce a diagnostic message if a hexadecimal constant - cannot be represented exactly in its evaluation format; the implementation should then - proceed with the translation of the program. -7 The translation-time conversion of floating constants should match the execution-time - conversion of character strings by library functions, such as strtod, given matching - inputs suitable for both conversions, the same result format, and default execution-time - rounding.75) - - - - - 75) The specification for the library functions recommends more accurate conversion than required for - floating constants (see 7.22.1.3). - -[page 66] - - 6.4.4.3 Enumeration constants - Syntax -1 enumeration-constant: - identifier - Semantics -2 An identifier declared as an enumeration constant has type int. - Forward references: enumeration specifiers (6.7.2.2). - 6.4.4.4 Character constants - Syntax -1 character-constant: - ' c-char-sequence ' - L' c-char-sequence ' - u' c-char-sequence ' - U' c-char-sequence ' - c-char-sequence: - c-char - c-char-sequence c-char - c-char: - any member of the source character set except - the single-quote ', backslash \, or new-line character - escape-sequence - escape-sequence: - simple-escape-sequence - octal-escape-sequence - hexadecimal-escape-sequence - universal-character-name - simple-escape-sequence: one of - \' \" \? \\ - \a \b \f \n \r \t \v - octal-escape-sequence: - \ octal-digit - \ octal-digit octal-digit - \ octal-digit octal-digit octal-digit - - - - -[page 67] - - hexadecimal-escape-sequence: - \x hexadecimal-digit - hexadecimal-escape-sequence hexadecimal-digit - Description -2 An integer character constant is a sequence of one or more multibyte characters enclosed - in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the - letter L, u, or U. With a few exceptions detailed later, the elements of the sequence are - any members of the source character set; they are mapped in an implementation-defined - manner to members of the execution character set. -3 The single-quote ', the double-quote ", the question-mark ?, the backslash \, and - arbitrary integer values are representable according to the following table of escape - sequences: - single quote ' \' - double quote " \" - question mark ? \? - backslash \ \\ - octal character \octal digits - hexadecimal character \x hexadecimal digits -4 The double-quote " and question-mark ? are representable either by themselves or by the - escape sequences \" and \?, respectively, but the single-quote ' and the backslash \ - shall be represented, respectively, by the escape sequences \' and \\. -5 The octal digits that follow the backslash in an octal escape sequence are taken to be part - of the construction of a single character for an integer character constant or of a single - wide character for a wide character constant. The numerical value of the octal integer so - formed specifies the value of the desired character or wide character. -6 The hexadecimal digits that follow the backslash and the letter x in a hexadecimal escape - sequence are taken to be part of the construction of a single character for an integer - character constant or of a single wide character for a wide character constant. The - numerical value of the hexadecimal integer so formed specifies the value of the desired - character or wide character. -7 Each octal or hexadecimal escape sequence is the longest sequence of characters that can - constitute the escape sequence. -8 In addition, characters not in the basic character set are representable by universal - character names and certain nongraphic characters are representable by escape sequences - consisting of the backslash \ followed by a lowercase letter: \a, \b, \f, \n, \r, \t, - and \v.76) - - - -[page 68] - - Constraints -9 The value of an octal or hexadecimal escape sequence shall be in the range of - representable values for the corresponding type: - Prefix Corresponding Type - none unsigned char - L the unsigned type corresponding to wchar_t - u char16_t - U char32_t - Semantics -10 An integer character constant has type int. The value of an integer character constant - containing a single character that maps to a single-byte execution character is the - numerical value of the representation of the mapped character interpreted as an integer. - The value of an integer character constant containing more than one character (e.g., - 'ab'), or containing a character or escape sequence that does not map to a single-byte - execution character, is implementation-defined. If an integer character constant contains - a single character or escape sequence, its value is the one that results when an object with - type char whose value is that of the single character or escape sequence is converted to - type int. -11 A wide character constant prefixed by the letter L has type wchar_t, an integer type - defined in the header; a wide character constant prefixed by the letter u or - U has type char16_t or char32_t, respectively, unsigned integer types defined in the - header. The value of a wide character constant containing a single - multibyte character that maps to a single member of the extended execution character set - is the wide character corresponding to that multibyte character, as defined by the - mbtowc, mbrtoc16, or mbrtoc32 function as appropriate for its type, with an - implementation-defined current locale. The value of a wide character constant containing - more than one multibyte character or a single multibyte character that maps to multiple - members of the extended execution character set, or containing a multibyte character or - escape sequence not represented in the extended execution character set, is - implementation-defined. -12 EXAMPLE 1 The construction '\0' is commonly used to represent the null character. - -13 EXAMPLE 2 Consider implementations that use two's-complement representation for integers and eight - bits for objects that have type char. In an implementation in which type char has the same range of - values as signed char, the integer character constant '\xFF' has the value -1; if type char has the - same range of values as unsigned char, the character constant '\xFF' has the value +255. - - - - - 76) The semantics of these characters were discussed in 5.2.2. If any other character follows a backslash, - the result is not a token and a diagnostic is required. See ''future language directions'' (6.11.4). - -[page 69] - -14 EXAMPLE 3 Even if eight bits are used for objects that have type char, the construction '\x123' - specifies an integer character constant containing only one character, since a hexadecimal escape sequence - is terminated only by a non-hexadecimal character. To specify an integer character constant containing the - two characters whose values are '\x12' and '3', the construction '\0223' may be used, since an octal - escape sequence is terminated after three octal digits. (The value of this two-character integer character - constant is implementation-defined.) - -15 EXAMPLE 4 Even if 12 or more bits are used for objects that have type wchar_t, the construction - L'\1234' specifies the implementation-defined value that results from the combination of the values - 0123 and '4'. - - Forward references: common definitions (7.19), the mbtowc function - (7.22.7.2), Unicode utilities (7.27). - 6.4.5 String literals - Syntax -1 string-literal: - encoding-prefixopt " s-char-sequenceopt " - encoding-prefix: - u8 - u - U - L - s-char-sequence: - s-char - s-char-sequence s-char - s-char: - any member of the source character set except - the double-quote ", backslash \, or new-line character - escape-sequence - Constraints -2 A sequence of adjacent string literal tokens shall not include both a wide string literal and - a UTF-8 string literal. - Description -3 A character string literal is a sequence of zero or more multibyte characters enclosed in - double-quotes, as in "xyz". A UTF-8 string literal is the same, except prefixed by u8. - A wide string literal is the same, except prefixed by the letter L, u, or U. -4 The same considerations apply to each element of the sequence in a string literal as if it - were in an integer character constant (for a character or UTF-8 string literal) or a wide - character constant (for a wide string literal), except that the single-quote ' is - representable either by itself or by the escape sequence \', but the double-quote " shall -[page 70] - - be represented by the escape sequence \". - Semantics -5 In translation phase 6, the multibyte character sequences specified by any sequence of - adjacent character and identically-prefixed string literal tokens are concatenated into a - single multibyte character sequence. If any of the tokens has an encoding prefix, the - resulting multibyte character sequence is treated as having the same prefix; otherwise, it - is treated as a character string literal. Whether differently-prefixed wide string literal - tokens can be concatenated and, if so, the treatment of the resulting multibyte character - sequence are implementation-defined. -6 In translation phase 7, a byte or code of value zero is appended to each multibyte - character sequence that results from a string literal or literals.77) The multibyte character - sequence is then used to initialize an array of static storage duration and length just - sufficient to contain the sequence. For character string literals, the array elements have - type char, and are initialized with the individual bytes of the multibyte character - sequence. For UTF-8 string literals, the array elements have type char, and are - initialized with the characters of the multibyte character sequence, as encoded in UTF-8. - For wide string literals prefixed by the letter L, the array elements have type wchar_t - and are initialized with the sequence of wide characters corresponding to the multibyte - character sequence, as defined by the mbstowcs function with an implementation- - defined current locale. For wide string literals prefixed by the letter u or U, the array - elements have type char16_t or char32_t, respectively, and are initialized with the - sequence of wide characters corresponding to the multibyte character sequence, as - defined by successive calls to the mbrtoc16, or mbrtoc32 function as appropriate for - its type, with an implementation-defined current locale. The value of a string literal - containing a multibyte character or escape sequence not represented in the execution - character set is implementation-defined. -7 It is unspecified whether these arrays are distinct provided their elements have the - appropriate values. If the program attempts to modify such an array, the behavior is - undefined. -8 EXAMPLE 1 This pair of adjacent character string literals - "\x12" "3" - produces a single character string literal containing the two characters whose values are '\x12' and '3', - because escape sequences are converted into single members of the execution character set just prior to - adjacent string literal concatenation. - -9 EXAMPLE 2 Each of the sequences of adjacent string literal tokens - - - - 77) A string literal need not be a string (see 7.1.1), because a null character may be embedded in it by a - \0 escape sequence. - -[page 71] - - "a" "b" L"c" - "a" L"b" "c" - L"a" "b" L"c" - L"a" L"b" L"c" - is equivalent to the string literal - L"abc" - Likewise, each of the sequences - "a" "b" u"c" - "a" u"b" "c" - u"a" "b" u"c" - u"a" u"b" u"c" - is equivalent to - u"abc" - - Forward references: common definitions (7.19), the mbstowcs - function (7.22.8.1), Unicode utilities (7.27). - 6.4.6 Punctuators - Syntax -1 punctuator: one of - [ ] ( ) { } . -> - ++ -- & * + - ~ ! - / % << >> < > <= >= == != ^ | && || - ? : ; ... - = *= /= %= += -= <<= >>= &= ^= |= - , # ## - <: :> <% %> %: %:%: - Semantics -2 A punctuator is a symbol that has independent syntactic and semantic significance. - Depending on context, it may specify an operation to be performed (which in turn may - yield a value or a function designator, produce a side effect, or some combination thereof) - in which case it is known as an operator (other forms of operator also exist in some - contexts). An operand is an entity on which an operator acts. - - - - -[page 72] - -3 In all aspects of the language, the six tokens78) - <: :> <% %> %: %:%: - behave, respectively, the same as the six tokens - [ ] { } # ## - except for their spelling.79) - Forward references: expressions (6.5), declarations (6.7), preprocessing directives - (6.10), statements (6.8). - 6.4.7 Header names - Syntax -1 header-name: - < h-char-sequence > - " q-char-sequence " - h-char-sequence: - h-char - h-char-sequence h-char - h-char: - any member of the source character set except - the new-line character and > - q-char-sequence: - q-char - q-char-sequence q-char - q-char: - any member of the source character set except - the new-line character and " - Semantics -2 The sequences in both forms of header names are mapped in an implementation-defined - manner to headers or external source file names as specified in 6.10.2. -3 If the characters ', \, ", //, or /* occur in the sequence between the < and > delimiters, - the behavior is undefined. Similarly, if the characters ', \, //, or /* occur in the - - - - - 78) These tokens are sometimes called ''digraphs''. - 79) Thus [ and <: behave differently when ''stringized'' (see 6.10.3.2), but can otherwise be freely - interchanged. - -[page 73] - - sequence between the " delimiters, the behavior is undefined.80) Header name - preprocessing tokens are recognized only within #include preprocessing directives and - in implementation-defined locations within #pragma directives.81) -4 EXAMPLE The following sequence of characters: - 0x3<1/a.h>1e2 - #include <1/a.h> - #define const.member@$ - forms the following sequence of preprocessing tokens (with each individual preprocessing token delimited - by a { on the left and a } on the right). - {0x3}{<}{1}{/}{a}{.}{h}{>}{1e2} - {#}{include} {<1/a.h>} - {#}{define} {const}{.}{member}{@}{$} - - Forward references: source file inclusion (6.10.2). - 6.4.8 Preprocessing numbers - Syntax -1 pp-number: - digit - . digit - pp-number digit - pp-number identifier-nondigit - pp-number e sign - pp-number E sign - pp-number p sign - pp-number P sign - pp-number . - Description -2 A preprocessing number begins with a digit optionally preceded by a period (.) and may - be followed by valid identifier characters and the character sequences e+, e-, E+, E-, - p+, p-, P+, or P-. -3 Preprocessing number tokens lexically include all floating and integer constant tokens. - Semantics -4 A preprocessing number does not have type or a value; it acquires both after a successful - conversion (as part of translation phase 7) to a floating constant token or an integer - constant token. - - - 80) Thus, sequences of characters that resemble escape sequences cause undefined behavior. - 81) For an example of a header name preprocessing token used in a #pragma directive, see 6.10.9. - -[page 74] - - 6.4.9 Comments -1 Except within a character constant, a string literal, or a comment, the characters /* - introduce a comment. The contents of such a comment are examined only to identify - multibyte characters and to find the characters */ that terminate it.82) -2 Except within a character constant, a string literal, or a comment, the characters // - introduce a comment that includes all multibyte characters up to, but not including, the - next new-line character. The contents of such a comment are examined only to identify - multibyte characters and to find the terminating new-line character. -3 EXAMPLE - "a//b" // four-character string literal - #include "//e" // undefined behavior - // */ // comment, not syntax error - f = g/**//h; // equivalent to f = g / h; - //\ - i(); // part of a two-line comment - /\ - / j(); // part of a two-line comment - #define glue(x,y) x##y - glue(/,/) k(); // syntax error, not comment - /*//*/ l(); // equivalent to l(); - m = n//**/o - + p; // equivalent to m = n + p; - - - - - 82) Thus, /* ... */ comments do not nest. - -[page 75] - - 6.5 Expressions -1 An expression is a sequence of operators and operands that specifies computation of a - value, or that designates an object or a function, or that generates side effects, or that - performs a combination thereof. The value computations of the operands of an operator - are sequenced before the value computation of the result of the operator. -2 If a side effect on a scalar object is unsequenced relative to either a different side effect - on the same scalar object or a value computation using the value of the same scalar - object, the behavior is undefined. If there are multiple allowable orderings of the - subexpressions of an expression, the behavior is undefined if such an unsequenced side - effect occurs in any of the orderings.83) -3 The grouping of operators and operands is indicated by the syntax.84) Except as specified - later, side effects and value computations of subexpressions are unsequenced.85) -4 Some operators (the unary operator ~, and the binary operators <<, >>, &, ^, and |, - collectively described as bitwise operators) are required to have operands that have - integer type. These operators yield values that depend on the internal representations of - integers, and have implementation-defined and undefined aspects for signed types. -5 If an exceptional condition occurs during the evaluation of an expression (that is, if the - result is not mathematically defined or not in the range of representable values for its - type), the behavior is undefined. - - - - 83) This paragraph renders undefined statement expressions such as - i = ++i + 1; - a[i++] = i; - while allowing - i = i + 1; - a[i] = i; - - 84) The syntax specifies the precedence of operators in the evaluation of an expression, which is the same - as the order of the major subclauses of this subclause, highest precedence first. Thus, for example, the - expressions allowed as the operands of the binary + operator (6.5.6) are those expressions defined in - 6.5.1 through 6.5.6. The exceptions are cast expressions (6.5.4) as operands of unary operators - (6.5.3), and an operand contained between any of the following pairs of operators: grouping - parentheses () (6.5.1), subscripting brackets [] (6.5.2.1), function-call parentheses () (6.5.2.2), and - the conditional operator ? : (6.5.15). - Within each major subclause, the operators have the same precedence. Left- or right-associativity is - indicated in each subclause by the syntax for the expressions discussed therein. - 85) In an expression that is evaluated more than once during the execution of a program, unsequenced and - indeterminately sequenced evaluations of its subexpressions need not be performed consistently in - different evaluations. - -[page 76] - -6 The effective type of an object for an access to its stored value is the declared type of the - object, if any.86) If a value is stored into an object having no declared type through an - lvalue having a type that is not a character type, then the type of the lvalue becomes the - effective type of the object for that access and for subsequent accesses that do not modify - the stored value. If a value is copied into an object having no declared type using - memcpy or memmove, or is copied as an array of character type, then the effective type - of the modified object for that access and for subsequent accesses that do not modify the - value is the effective type of the object from which the value is copied, if it has one. For - all other accesses to an object having no declared type, the effective type of the object is - simply the type of the lvalue used for the access. -7 An object shall have its stored value accessed only by an lvalue expression that has one of - the following types:87) - -- a type compatible with the effective type of the object, - -- a qualified version of a type compatible with the effective type of the object, - -- a type that is the signed or unsigned type corresponding to the effective type of the - object, - -- a type that is the signed or unsigned type corresponding to a qualified version of the - effective type of the object, - -- an aggregate or union type that includes one of the aforementioned types among its - members (including, recursively, a member of a subaggregate or contained union), or - -- a character type. -8 A floating expression may be contracted, that is, evaluated as though it were a single - operation, thereby omitting rounding errors implied by the source code and the - expression evaluation method.88) The FP_CONTRACT pragma in provides a - way to disallow contracted expressions. Otherwise, whether and how expressions are - contracted is implementation-defined.89) - Forward references: the FP_CONTRACT pragma (7.12.2), copying functions (7.23.2). - - - 86) Allocated objects have no declared type. - 87) The intent of this list is to specify those circumstances in which an object may or may not be aliased. - 88) The intermediate operations in the contracted expression are evaluated as if to infinite precision and - range, while the final operation is rounded to the format determined by the expression evaluation - method. A contracted expression might also omit the raising of floating-point exceptions. - 89) This license is specifically intended to allow implementations to exploit fast machine instructions that - combine multiple C operators. As contractions potentially undermine predictability, and can even - decrease accuracy for containing expressions, their use needs to be well-defined and clearly - documented. - -[page 77] - - 6.5.1 Primary expressions - Syntax -1 primary-expression: - identifier - constant - string-literal - ( expression ) - generic-selection - Semantics -2 An identifier is a primary expression, provided it has been declared as designating an - object (in which case it is an lvalue) or a function (in which case it is a function - designator).90) -3 A constant is a primary expression. Its type depends on its form and value, as detailed in - 6.4.4. -4 A string literal is a primary expression. It is an lvalue with type as detailed in 6.4.5. -5 A parenthesized expression is a primary expression. Its type and value are identical to - those of the unparenthesized expression. It is an lvalue, a function designator, or a void - expression if the unparenthesized expression is, respectively, an lvalue, a function - designator, or a void expression. - Forward references: declarations (6.7). - 6.5.1.1 Generic selection - Syntax -1 generic-selection: - _Generic ( assignment-expression , generic-assoc-list ) - generic-assoc-list: - generic-association - generic-assoc-list , generic-association - generic-association: - type-name : assignment-expression - default : assignment-expression - Constraints -2 A generic selection shall have no more than one default generic association. The type - name in a generic association shall specify a complete object type other than a variably - - 90) Thus, an undeclared identifier is a violation of the syntax. - -[page 78] - - modified type. No two generic associations in the same generic selection shall specify - compatible types. The controlling expression of a generic selection shall have type - compatible with at most one of the types named in its generic association list. If a - generic selection has no default generic association, its controlling expression shall - have type compatible with exactly one of the types named in its generic association list. - Semantics -3 The controlling expression of a generic selection is not evaluated. If a generic selection - has a generic association with a type name that is compatible with the type of the - controlling expression, then the result expression of the generic selection is the - expression in that generic association. Otherwise, the result expression of the generic - selection is the expression in the default generic association. None of the expressions - from any other generic association of the generic selection is evaluated. -4 The type and value of a generic selection are identical to those of its result expression. It - is an lvalue, a function designator, or a void expression if its result expression is, - respectively, an lvalue, a function designator, or a void expression. -5 EXAMPLE The cbrt type-generic macro could be implemented as follows: - #define cbrt(X) _Generic((X), \ - long double: cbrtl, \ - default: cbrt, \ - float: cbrtf \ - )(X) - - 6.5.2 Postfix operators - Syntax -1 postfix-expression: - primary-expression - postfix-expression [ expression ] - postfix-expression ( argument-expression-listopt ) - postfix-expression . identifier - postfix-expression -> identifier - postfix-expression ++ - postfix-expression -- - ( type-name ) { initializer-list } - ( type-name ) { initializer-list , } - argument-expression-list: - assignment-expression - argument-expression-list , assignment-expression - - - - -[page 79] - - 6.5.2.1 Array subscripting - Constraints -1 One of the expressions shall have type ''pointer to complete object type'', the other - expression shall have integer type, and the result has type ''type''. - Semantics -2 A postfix expression followed by an expression in square brackets [] is a subscripted - designation of an element of an array object. The definition of the subscript operator [] - is that E1[E2] is identical to (*((E1)+(E2))). Because of the conversion rules that - apply to the binary + operator, if E1 is an array object (equivalently, a pointer to the - initial element of an array object) and E2 is an integer, E1[E2] designates the E2-th - element of E1 (counting from zero). -3 Successive subscript operators designate an element of a multidimensional array object. - If E is an n-dimensional array (n >= 2) with dimensions i x j x . . . x k, then E (used as - other than an lvalue) is converted to a pointer to an (n - 1)-dimensional array with - dimensions j x . . . x k. If the unary * operator is applied to this pointer explicitly, or - implicitly as a result of subscripting, the result is the referenced (n - 1)-dimensional - array, which itself is converted into a pointer if used as other than an lvalue. It follows - from this that arrays are stored in row-major order (last subscript varies fastest). -4 EXAMPLE Consider the array object defined by the declaration - int x[3][5]; - Here x is a 3 x 5 array of ints; more precisely, x is an array of three element objects, each of which is an - array of five ints. In the expression x[i], which is equivalent to (*((x)+(i))), x is first converted to - a pointer to the initial array of five ints. Then i is adjusted according to the type of x, which conceptually - entails multiplying i by the size of the object to which the pointer points, namely an array of five int - objects. The results are added and indirection is applied to yield an array of five ints. When used in the - expression x[i][j], that array is in turn converted to a pointer to the first of the ints, so x[i][j] - yields an int. - - Forward references: additive operators (6.5.6), address and indirection operators - (6.5.3.2), array declarators (6.7.6.2). - 6.5.2.2 Function calls - Constraints -1 The expression that denotes the called function91) shall have type pointer to function - returning void or returning a complete object type other than an array type. -2 If the expression that denotes the called function has a type that includes a prototype, the - number of arguments shall agree with the number of parameters. Each argument shall - - - 91) Most often, this is the result of converting an identifier that is a function designator. - -[page 80] - - have a type such that its value may be assigned to an object with the unqualified version - of the type of its corresponding parameter. - Semantics -3 A postfix expression followed by parentheses () containing a possibly empty, comma- - separated list of expressions is a function call. The postfix expression denotes the called - function. The list of expressions specifies the arguments to the function. -4 An argument may be an expression of any complete object type. In preparing for the call - to a function, the arguments are evaluated, and each parameter is assigned the value of the - corresponding argument.92) -5 If the expression that denotes the called function has type pointer to function returning an - object type, the function call expression has the same type as that object type, and has the - value determined as specified in 6.8.6.4. Otherwise, the function call has type void. -6 If the expression that denotes the called function has a type that does not include a - prototype, the integer promotions are performed on each argument, and arguments that - have type float are promoted to double. These are called the default argument - promotions. If the number of arguments does not equal the number of parameters, the - behavior is undefined. If the function is defined with a type that includes a prototype, and - either the prototype ends with an ellipsis (, ...) or the types of the arguments after - promotion are not compatible with the types of the parameters, the behavior is undefined. - If the function is defined with a type that does not include a prototype, and the types of - the arguments after promotion are not compatible with those of the parameters after - promotion, the behavior is undefined, except for the following cases: - -- one promoted type is a signed integer type, the other promoted type is the - corresponding unsigned integer type, and the value is representable in both types; - -- both types are pointers to qualified or unqualified versions of a character type or - void. -7 If the expression that denotes the called function has a type that does include a prototype, - the arguments are implicitly converted, as if by assignment, to the types of the - corresponding parameters, taking the type of each parameter to be the unqualified version - of its declared type. The ellipsis notation in a function prototype declarator causes - argument type conversion to stop after the last declared parameter. The default argument - promotions are performed on trailing arguments. - - - - 92) A function may change the values of its parameters, but these changes cannot affect the values of the - arguments. On the other hand, it is possible to pass a pointer to an object, and the function may - change the value of the object pointed to. A parameter declared to have array or function type is - adjusted to have a pointer type as described in 6.9.1. - -[page 81] - -8 No other conversions are performed implicitly; in particular, the number and types of - arguments are not compared with those of the parameters in a function definition that - does not include a function prototype declarator. -9 If the function is defined with a type that is not compatible with the type (of the - expression) pointed to by the expression that denotes the called function, the behavior is - undefined. -10 There is a sequence point after the evaluations of the function designator and the actual - arguments but before the actual call. Every evaluation in the calling function (including - other function calls) that is not otherwise specifically sequenced before or after the - execution of the body of the called function is indeterminately sequenced with respect to - the execution of the called function.93) -11 Recursive function calls shall be permitted, both directly and indirectly through any chain - of other functions. -12 EXAMPLE In the function call - (*pf[f1()]) (f2(), f3() + f4()) - the functions f1, f2, f3, and f4 may be called in any order. All side effects have to be completed before - the function pointed to by pf[f1()] is called. - - Forward references: function declarators (including prototypes) (6.7.6.3), function - definitions (6.9.1), the return statement (6.8.6.4), simple assignment (6.5.16.1). - 6.5.2.3 Structure and union members - Constraints -1 The first operand of the . operator shall have a qualified or unqualified structure or union - type, and the second operand shall name a member of that type. -2 The first operand of the -> operator shall have type ''pointer to qualified or unqualified - structure'' or ''pointer to qualified or unqualified union'', and the second operand shall - name a member of the type pointed to. - Semantics -3 A postfix expression followed by the . operator and an identifier designates a member of - a structure or union object. The value is that of the named member,94) and is an lvalue if - the first expression is an lvalue. If the first expression has qualified type, the result has - the so-qualified version of the type of the designated member. - - 93) In other words, function executions do not ''interleave'' with each other. - 94) If the member used to access the contents of a union object is not the same as the member last used to - store a value in the object, the appropriate part of the object representation of the value is reinterpreted - as an object representation in the new type as described in 6.2.6 (a process sometimes called ''type - punning''). This might be a trap representation. - -[page 82] - -4 A postfix expression followed by the -> operator and an identifier designates a member - of a structure or union object. The value is that of the named member of the object to - which the first expression points, and is an lvalue.95) If the first expression is a pointer to - a qualified type, the result has the so-qualified version of the type of the designated - member. -5 Accessing a member of an _Atomic-qualified structure or union object results in - undefined behavior.96) -6 One special guarantee is made in order to simplify the use of unions: if a union contains - several structures that share a common initial sequence (see below), and if the union - object currently contains one of these structures, it is permitted to inspect the common - initial part of any of them anywhere that a declaration of the completed type of the union - is visible. Two structures share a common initial sequence if corresponding members - have compatible types (and, for bit-fields, the same widths) for a sequence of one or more - initial members. -7 EXAMPLE 1 If f is a function returning a structure or union, and x is a member of that structure or - union, f().x is a valid postfix expression but is not an lvalue. - -8 EXAMPLE 2 In: - struct s { int i; const int ci; }; - struct s s; - const struct s cs; - volatile struct s vs; - the various members have the types: - s.i int - s.ci const int - cs.i const int - cs.ci const int - vs.i volatile int - vs.ci volatile const int - - - - - 95) If &E is a valid pointer expression (where & is the ''address-of '' operator, which generates a pointer to - its operand), the expression (&E)->MOS is the same as E.MOS. - 96) A data race would occur if access to the entire structure or union in one thread conflicts with access to - a member from another thread, where at least one access is a modification. Such a data race results in - undefined behavior. - -[page 83] - -9 EXAMPLE 3 The following is a valid fragment: - union { - struct { - int alltypes; - } n; - struct { - int type; - int intnode; - } ni; - struct { - int type; - double doublenode; - } nf; - } u; - u.nf.type = 1; - u.nf.doublenode = 3.14; - /* ... */ - if (u.n.alltypes == 1) - if (sin(u.nf.doublenode) == 0.0) - /* ... */ - The following is not a valid fragment (because the union type is not visible within function f): - struct t1 { int m; }; - struct t2 { int m; }; - int f(struct t1 *p1, struct t2 *p2) - { - if (p1->m < 0) - p2->m = -p2->m; - return p1->m; - } - int g() - { - union { - struct t1 s1; - struct t2 s2; - } u; - /* ... */ - return f(&u.s1, &u.s2); - } - - Forward references: address and indirection operators (6.5.3.2), structure and union - specifiers (6.7.2.1). - - - - -[page 84] - - 6.5.2.4 Postfix increment and decrement operators - Constraints -1 The operand of the postfix increment or decrement operator shall have qualified or - unqualified real or pointer type and shall be a modifiable lvalue. - Semantics -2 The result of the postfix ++ operator is the value of the operand. As a side effect, the - value of the operand object is incremented (that is, the value 1 of the appropriate type is - added to it). See the discussions of additive operators and compound assignment for - information on constraints, types, and conversions and the effects of operations on - pointers. The value computation of the result is sequenced before the side effect of - updating the stored value of the operand. With respect to an indeterminately-sequenced - function call, the operation of postfix ++ is a single evaluation. Postfix ++ on an object - with _Atomic-qualified type is a read-modify-write operation with - 97) - memory_order_seq_cst memory order semantics. -3 The postfix -- operator is analogous to the postfix ++ operator, except that the value of - the operand is decremented (that is, the value 1 of the appropriate type is subtracted from - it). - Forward references: additive operators (6.5.6), compound assignment (6.5.16.2). - 6.5.2.5 Compound literals - Constraints -1 The type name shall specify a complete object type or an array of unknown size, but not a - variable length array type. -2 All the constraints for initializer lists in 6.7.9 also apply to compound literals. - Semantics -3 A postfix expression that consists of a parenthesized type name followed by a brace- - enclosed list of initializers is a compound literal. It provides an unnamed object whose - value is given by the initializer list.98) - - - 97) Where a pointer to an atomic object can be formed, this is equivalent to the following code sequence - where T is the type of E: - T tmp; - T result = E; - do { - tmp = result + 1; - } while (!atomic_compare_exchange_strong(&E, &result, tmp)); - with result being the result of the operation. - -[page 85] - -4 If the type name specifies an array of unknown size, the size is determined by the - initializer list as specified in 6.7.9, and the type of the compound literal is that of the - completed array type. Otherwise (when the type name specifies an object type), the type - of the compound literal is that specified by the type name. In either case, the result is an - lvalue. -5 The value of the compound literal is that of an unnamed object initialized by the - initializer list. If the compound literal occurs outside the body of a function, the object - has static storage duration; otherwise, it has automatic storage duration associated with - the enclosing block. -6 All the semantic rules for initializer lists in 6.7.9 also apply to compound literals.99) -7 String literals, and compound literals with const-qualified types, need not designate - distinct objects.100) -8 EXAMPLE 1 The file scope definition - int *p = (int []){2, 4}; - initializes p to point to the first element of an array of two ints, the first having the value two and the - second, four. The expressions in this compound literal are required to be constant. The unnamed object - has static storage duration. - -9 EXAMPLE 2 In contrast, in - void f(void) - { - int *p; - /*...*/ - p = (int [2]){*p}; - /*...*/ - } - p is assigned the address of the first element of an array of two ints, the first having the value previously - pointed to by p and the second, zero. The expressions in this compound literal need not be constant. The - unnamed object has automatic storage duration. - -10 EXAMPLE 3 Initializers with designations can be combined with compound literals. Structure objects - created using compound literals can be passed to functions without depending on member order: - drawline((struct point){.x=1, .y=1}, - (struct point){.x=3, .y=4}); - Or, if drawline instead expected pointers to struct point: - - - - 98) Note that this differs from a cast expression. For example, a cast specifies a conversion to scalar types - or void only, and the result of a cast expression is not an lvalue. - 99) For example, subobjects without explicit initializers are initialized to zero. - 100) This allows implementations to share storage for string literals and constant compound literals with - the same or overlapping representations. - -[page 86] - - drawline(&(struct point){.x=1, .y=1}, - &(struct point){.x=3, .y=4}); - -11 EXAMPLE 4 A read-only compound literal can be specified through constructions like: - (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6} - -12 EXAMPLE 5 The following three expressions have different meanings: - "/tmp/fileXXXXXX" - (char []){"/tmp/fileXXXXXX"} - (const char []){"/tmp/fileXXXXXX"} - The first always has static storage duration and has type array of char, but need not be modifiable; the last - two have automatic storage duration when they occur within the body of a function, and the first of these - two is modifiable. - -13 EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory - and can even be shared. For example, - (const char []){"abc"} == "abc" - might yield 1 if the literals' storage is shared. - -14 EXAMPLE 7 Since compound literals are unnamed, a single compound literal cannot specify a circularly - linked object. For example, there is no way to write a self-referential compound literal that could be used - as the function argument in place of the named object endless_zeros below: - struct int_list { int car; struct int_list *cdr; }; - struct int_list endless_zeros = {0, &endless_zeros}; - eval(endless_zeros); - -15 EXAMPLE 8 Each compound literal creates only a single object in a given scope: - struct s { int i; }; - int f (void) - { - struct s *p = 0, *q; - int j = 0; - again: - q = p, p = &((struct s){ j++ }); - if (j < 2) goto again; - return p == q && q->i == 1; - } - The function f() always returns the value 1. -16 Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the - lifetime of the unnamed object would be the body of the loop only, and on entry next time around p would - have an indeterminate value, which would result in undefined behavior. - - Forward references: type names (6.7.7), initialization (6.7.9). - - - - -[page 87] - - 6.5.3 Unary operators - Syntax -1 unary-expression: - postfix-expression - ++ unary-expression - -- unary-expression - unary-operator cast-expression - sizeof unary-expression - sizeof ( type-name ) - alignof ( type-name ) - unary-operator: one of - & * + - ~ ! - 6.5.3.1 Prefix increment and decrement operators - Constraints -1 The operand of the prefix increment or decrement operator shall have qualified or - unqualified real or pointer type and shall be a modifiable lvalue. - Semantics -2 The value of the operand of the prefix ++ operator is incremented. The result is the new - value of the operand after incrementation. The expression ++E is equivalent to (E+=1). - See the discussions of additive operators and compound assignment for information on - constraints, types, side effects, and conversions and the effects of operations on pointers. -3 The prefix -- operator is analogous to the prefix ++ operator, except that the value of the - operand is decremented. - Forward references: additive operators (6.5.6), compound assignment (6.5.16.2). - 6.5.3.2 Address and indirection operators - Constraints -1 The operand of the unary & operator shall be either a function designator, the result of a - [] or unary * operator, or an lvalue that designates an object that is not a bit-field and is - not declared with the register storage-class specifier. -2 The operand of the unary * operator shall have pointer type. - Semantics -3 The unary & operator yields the address of its operand. If the operand has type ''type'', - the result has type ''pointer to type''. If the operand is the result of a unary * operator, - neither that operator nor the & operator is evaluated and the result is as if both were - omitted, except that the constraints on the operators still apply and the result is not an - -[page 88] - - lvalue. Similarly, if the operand is the result of a [] operator, neither the & operator nor - the unary * that is implied by the [] is evaluated and the result is as if the & operator - were removed and the [] operator were changed to a + operator. Otherwise, the result is - a pointer to the object or function designated by its operand. -4 The unary * operator denotes indirection. If the operand points to a function, the result is - a function designator; if it points to an object, the result is an lvalue designating the - object. If the operand has type ''pointer to type'', the result has type ''type''. If an - invalid value has been assigned to the pointer, the behavior of the unary * operator is - undefined.101) - Forward references: storage-class specifiers (6.7.1), structure and union specifiers - (6.7.2.1). - 6.5.3.3 Unary arithmetic operators - Constraints -1 The operand of the unary + or - operator shall have arithmetic type; of the ~ operator, - integer type; of the ! operator, scalar type. - Semantics -2 The result of the unary + operator is the value of its (promoted) operand. The integer - promotions are performed on the operand, and the result has the promoted type. -3 The result of the unary - operator is the negative of its (promoted) operand. The integer - promotions are performed on the operand, and the result has the promoted type. -4 The result of the ~ operator is the bitwise complement of its (promoted) operand (that is, - each bit in the result is set if and only if the corresponding bit in the converted operand is - not set). The integer promotions are performed on the operand, and the result has the - promoted type. If the promoted type is an unsigned type, the expression ~E is equivalent - to the maximum value representable in that type minus E. -5 The result of the logical negation operator ! is 0 if the value of its operand compares - unequal to 0, 1 if the value of its operand compares equal to 0. The result has type int. - The expression !E is equivalent to (0==E). - - - - 101) Thus, &*E is equivalent to E (even if E is a null pointer), and &(E1[E2]) to ((E1)+(E2)). It is - always true that if E is a function designator or an lvalue that is a valid operand of the unary & - operator, *&E is a function designator or an lvalue equal to E. If *P is an lvalue and T is the name of - an object pointer type, *(T)P is an lvalue that has a type compatible with that to which T points. - Among the invalid values for dereferencing a pointer by the unary * operator are a null pointer, an - address inappropriately aligned for the type of object pointed to, and the address of an object after the - end of its lifetime. - -[page 89] - - 6.5.3.4 The sizeof and alignof operators - Constraints -1 The sizeof operator shall not be applied to an expression that has function type or an - incomplete type, to the parenthesized name of such a type, or to an expression that - designates a bit-field member. The alignof operator shall not be applied to a function - type or an incomplete type. - Semantics -2 The sizeof operator yields the size (in bytes) of its operand, which may be an - expression or the parenthesized name of a type. The size is determined from the type of - the operand. The result is an integer. If the type of the operand is a variable length array - type, the operand is evaluated; otherwise, the operand is not evaluated and the result is an - integer constant. -3 The alignof operator yields the alignment requirement of its operand type. The result - is an integer constant. When applied to an array type, the result is the alignment - requirement of the element type. -4 When sizeof is applied to an operand that has type char, unsigned char, or - signed char, (or a qualified version thereof) the result is 1. When applied to an - operand that has array type, the result is the total number of bytes in the array.102) When - applied to an operand that has structure or union type, the result is the total number of - bytes in such an object, including internal and trailing padding. -5 The value of the result of both operators is implementation-defined, and its type (an - unsigned integer type) is size_t, defined in (and other headers). -6 EXAMPLE 1 A principal use of the sizeof operator is in communication with routines such as storage - allocators and I/O systems. A storage-allocation function might accept a size (in bytes) of an object to - allocate and return a pointer to void. For example: - extern void *alloc(size_t); - double *dp = alloc(sizeof *dp); - The implementation of the alloc function should ensure that its return value is aligned suitably for - conversion to a pointer to double. - -7 EXAMPLE 2 Another use of the sizeof operator is to compute the number of elements in an array: - sizeof array / sizeof array[0] - -8 EXAMPLE 3 In this example, the size of a variable length array is computed and returned from a - function: - #include - - - - 102) When applied to a parameter declared to have array or function type, the sizeof operator yields the - size of the adjusted (pointer) type (see 6.9.1). - -[page 90] - - size_t fsize3(int n) - { - char b[n+3]; // variable length array - return sizeof b; // execution time sizeof - } - int main() - { - size_t size; - size = fsize3(10); // fsize3 returns 13 - return 0; - } - - Forward references: common definitions (7.19), declarations (6.7), - structure and union specifiers (6.7.2.1), type names (6.7.7), array declarators (6.7.6.2). - 6.5.4 Cast operators - Syntax -1 cast-expression: - unary-expression - ( type-name ) cast-expression - Constraints -2 Unless the type name specifies a void type, the type name shall specify qualified or - unqualified scalar type and the operand shall have scalar type. -3 Conversions that involve pointers, other than where permitted by the constraints of - 6.5.16.1, shall be specified by means of an explicit cast. -4 A pointer type shall not be converted to any floating type. A floating type shall not be - converted to any pointer type. - Semantics -5 Preceding an expression by a parenthesized type name converts the value of the - expression to the named type. This construction is called a cast.103) A cast that specifies - no conversion has no effect on the type or value of an expression. -6 If the value of the expression is represented with greater precision or range than required - by the type named by the cast (6.3.1.8), then the cast specifies a conversion even if the - type of the expression is the same as the named type. - Forward references: equality operators (6.5.9), function declarators (including - prototypes) (6.7.6.3), simple assignment (6.5.16.1), type names (6.7.7). - - - - 103) A cast does not yield an lvalue. Thus, a cast to a qualified type has the same effect as a cast to the - unqualified version of the type. - -[page 91] - - 6.5.5 Multiplicative operators - Syntax -1 multiplicative-expression: - cast-expression - multiplicative-expression * cast-expression - multiplicative-expression / cast-expression - multiplicative-expression % cast-expression - Constraints -2 Each of the operands shall have arithmetic type. The operands of the % operator shall - have integer type. - Semantics -3 The usual arithmetic conversions are performed on the operands. -4 The result of the binary * operator is the product of the operands. -5 The result of the / operator is the quotient from the division of the first operand by the - second; the result of the % operator is the remainder. In both operations, if the value of - the second operand is zero, the behavior is undefined. -6 When integers are divided, the result of the / operator is the algebraic quotient with any - fractional part discarded.104) If the quotient a/b is representable, the expression - (a/b)*b + a%b shall equal a; otherwise, the behavior of both a/b and a%b is - undefined. - 6.5.6 Additive operators - Syntax -1 additive-expression: - multiplicative-expression - additive-expression + multiplicative-expression - additive-expression - multiplicative-expression - Constraints -2 For addition, either both operands shall have arithmetic type, or one operand shall be a - pointer to a complete object type and the other shall have integer type. (Incrementing is - equivalent to adding 1.) -3 For subtraction, one of the following shall hold: - - - - - 104) This is often called ''truncation toward zero''. - -[page 92] - - -- both operands have arithmetic type; - -- both operands are pointers to qualified or unqualified versions of compatible complete - object types; or - -- the left operand is a pointer to a complete object type and the right operand has - integer type. - (Decrementing is equivalent to subtracting 1.) - Semantics -4 If both operands have arithmetic type, the usual arithmetic conversions are performed on - them. -5 The result of the binary + operator is the sum of the operands. -6 The result of the binary - operator is the difference resulting from the subtraction of the - second operand from the first. -7 For the purposes of these operators, a pointer to an object that is not an element of an - array behaves the same as a pointer to the first element of an array of length one with the - type of the object as its element type. -8 When an expression that has integer type is added to or subtracted from a pointer, the - result has the type of the pointer operand. If the pointer operand points to an element of - an array object, and the array is large enough, the result points to an element offset from - the original element such that the difference of the subscripts of the resulting and original - array elements equals the integer expression. In other words, if the expression P points to - the i-th element of an array object, the expressions (P)+N (equivalently, N+(P)) and - (P)-N (where N has the value n) point to, respectively, the i+n-th and i-n-th elements of - the array object, provided they exist. Moreover, if the expression P points to the last - element of an array object, the expression (P)+1 points one past the last element of the - array object, and if the expression Q points one past the last element of an array object, - the expression (Q)-1 points to the last element of the array object. If both the pointer - operand and the result point to elements of the same array object, or one past the last - element of the array object, the evaluation shall not produce an overflow; otherwise, the - behavior is undefined. If the result points one past the last element of the array object, it - shall not be used as the operand of a unary * operator that is evaluated. -9 When two pointers are subtracted, both shall point to elements of the same array object, - or one past the last element of the array object; the result is the difference of the - subscripts of the two array elements. The size of the result is implementation-defined, - and its type (a signed integer type) is ptrdiff_t defined in the header. - If the result is not representable in an object of that type, the behavior is undefined. In - other words, if the expressions P and Q point to, respectively, the i-th and j-th elements of - an array object, the expression (P)-(Q) has the value i-j provided the value fits in an - -[page 93] - - object of type ptrdiff_t. Moreover, if the expression P points either to an element of - an array object or one past the last element of an array object, and the expression Q points - to the last element of the same array object, the expression ((Q)+1)-(P) has the same - value as ((Q)-(P))+1 and as -((P)-((Q)+1)), and has the value zero if the - expression P points one past the last element of the array object, even though the - expression (Q)+1 does not point to an element of the array object.105) -10 EXAMPLE Pointer arithmetic is well defined with pointers to variable length array types. - { - int n = 4, m = 3; - int a[n][m]; - int (*p)[m] = a; // p == &a[0] - p += 1; // p == &a[1] - (*p)[2] = 99; // a[1][2] == 99 - n = p - a; // n == 1 - } -11 If array a in the above example were declared to be an array of known constant size, and pointer p were - declared to be a pointer to an array of the same known constant size (pointing to a), the results would be - the same. - - Forward references: array declarators (6.7.6.2), common definitions - (7.19). - 6.5.7 Bitwise shift operators - Syntax -1 shift-expression: - additive-expression - shift-expression << additive-expression - shift-expression >> additive-expression - Constraints -2 Each of the operands shall have integer type. - Semantics -3 The integer promotions are performed on each of the operands. The type of the result is - that of the promoted left operand. If the value of the right operand is negative or is - - 105) Another way to approach pointer arithmetic is first to convert the pointer(s) to character pointer(s): In - this scheme the integer expression added to or subtracted from the converted pointer is first multiplied - by the size of the object originally pointed to, and the resulting pointer is converted back to the - original type. For pointer subtraction, the result of the difference between the character pointers is - similarly divided by the size of the object originally pointed to. - When viewed in this way, an implementation need only provide one extra byte (which may overlap - another object in the program) just after the end of the object in order to satisfy the ''one past the last - element'' requirements. - -[page 94] - - greater than or equal to the width of the promoted left operand, the behavior is undefined. -4 The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are filled with - zeros. If E1 has an unsigned type, the value of the result is E1 x 2E2 , reduced modulo - one more than the maximum value representable in the result type. If E1 has a signed - type and nonnegative value, and E1 x 2E2 is representable in the result type, then that is - the resulting value; otherwise, the behavior is undefined. -5 The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an unsigned type - or if E1 has a signed type and a nonnegative value, the value of the result is the integral - part of the quotient of E1 / 2E2 . If E1 has a signed type and a negative value, the - resulting value is implementation-defined. - 6.5.8 Relational operators - Syntax -1 relational-expression: - shift-expression - relational-expression < shift-expression - relational-expression > shift-expression - relational-expression <= shift-expression - relational-expression >= shift-expression - Constraints -2 One of the following shall hold: - -- both operands have real type; or - -- both operands are pointers to qualified or unqualified versions of compatible object - types. - Semantics -3 If both of the operands have arithmetic type, the usual arithmetic conversions are - performed. -4 For the purposes of these operators, a pointer to an object that is not an element of an - array behaves the same as a pointer to the first element of an array of length one with the - type of the object as its element type. -5 When two pointers are compared, the result depends on the relative locations in the - address space of the objects pointed to. If two pointers to object types both point to the - same object, or both point one past the last element of the same array object, they - compare equal. If the objects pointed to are members of the same aggregate object, - pointers to structure members declared later compare greater than pointers to members - declared earlier in the structure, and pointers to array elements with larger subscript - values compare greater than pointers to elements of the same array with lower subscript - -[page 95] - - values. All pointers to members of the same union object compare equal. If the - expression P points to an element of an array object and the expression Q points to the - last element of the same array object, the pointer expression Q+1 compares greater than - P. In all other cases, the behavior is undefined. -6 Each of the operators < (less than), > (greater than), <= (less than or equal to), and >= - (greater than or equal to) shall yield 1 if the specified relation is true and 0 if it is - false.106) The result has type int. - 6.5.9 Equality operators - Syntax -1 equality-expression: - relational-expression - equality-expression == relational-expression - equality-expression != relational-expression - Constraints -2 One of the following shall hold: - -- both operands have arithmetic type; - -- both operands are pointers to qualified or unqualified versions of compatible types; - -- one operand is a pointer to an object type and the other is a pointer to a qualified or - unqualified version of void; or - -- one operand is a pointer and the other is a null pointer constant. - Semantics -3 The == (equal to) and != (not equal to) operators are analogous to the relational - operators except for their lower precedence.107) Each of the operators yields 1 if the - specified relation is true and 0 if it is false. The result has type int. For any pair of - operands, exactly one of the relations is true. -4 If both of the operands have arithmetic type, the usual arithmetic conversions are - performed. Values of complex types are equal if and only if both their real parts are equal - and also their imaginary parts are equal. Any two values of arithmetic types from - different type domains are equal if and only if the results of their conversions to the - (complex) result type determined by the usual arithmetic conversions are equal. - - - - 106) The expression a>= &= ^= |= - Constraints -2 An assignment operator shall have a modifiable lvalue as its left operand. - Semantics -3 An assignment operator stores a value in the object designated by the left operand. An - assignment expression has the value of the left operand after the assignment,110) but is not - an lvalue. The type of an assignment expression is the type of the left operand unless the - left operand has qualified type, in which case it is the unqualified version of the type of - the left operand. The side effect of updating the stored value of the left operand is - sequenced after the value computations of the left and right operands. The evaluations of - the operands are unsequenced. - - - - - 110) The implementation is permitted to read the object to determine the value but is not required to, even - when the object has volatile-qualified type. - -[page 101] - - 6.5.16.1 Simple assignment - Constraints -1 One of the following shall hold:111) - -- the left operand has qualified or unqualified arithmetic type and the right has - arithmetic type; - -- the left operand has a qualified or unqualified version of a structure or union type - compatible with the type of the right; - -- both operands are pointers to qualified or unqualified versions of compatible types, - and the type pointed to by the left has all the qualifiers of the type pointed to by the - right; - -- one operand is a pointer to an object type and the other is a pointer to a qualified or - unqualified version of void, and the type pointed to by the left has all the qualifiers - of the type pointed to by the right; - -- the left operand is a pointer and the right is a null pointer constant; or - -- the left operand has type _Bool and the right is a pointer. - Semantics -2 In simple assignment (=), the value of the right operand is converted to the type of the - assignment expression and replaces the value stored in the object designated by the left - operand. -3 If the value being stored in an object is read from another object that overlaps in any way - the storage of the first object, then the overlap shall be exact and the two objects shall - have qualified or unqualified versions of a compatible type; otherwise, the behavior is - undefined. -4 EXAMPLE 1 In the program fragment - int f(void); - char c; - /* ... */ - if ((c = f()) == -1) - /* ... */ - the int value returned by the function may be truncated when stored in the char, and then converted back - to int width prior to the comparison. In an implementation in which ''plain'' char has the same range of - values as unsigned char (and char is narrower than int), the result of the conversion cannot be - - - - 111) The asymmetric appearance of these constraints with respect to type qualifiers is due to the conversion - (specified in 6.3.2.1) that changes lvalues to ''the value of the expression'' and thus removes any type - qualifiers that were applied to the type category of the expression (for example, it removes const but - not volatile from the type int volatile * const). - -[page 102] - - negative, so the operands of the comparison can never compare equal. Therefore, for full portability, the - variable c should be declared as int. - -5 EXAMPLE 2 In the fragment: - char c; - int i; - long l; - l = (c = i); - the value of i is converted to the type of the assignment expression c = i, that is, char type. The value - of the expression enclosed in parentheses is then converted to the type of the outer assignment expression, - that is, long int type. - -6 EXAMPLE 3 Consider the fragment: - const char **cpp; - char *p; - const char c = 'A'; - cpp = &p; // constraint violation - *cpp = &c; // valid - *p = 0; // valid - The first assignment is unsafe because it would allow the following valid code to attempt to change the - value of the const object c. - - 6.5.16.2 Compound assignment - Constraints -1 For the operators += and -= only, either the left operand shall be a pointer to a complete - object type and the right shall have integer type, or the left operand shall have qualified or - unqualified arithmetic type and the right shall have arithmetic type. -2 For the other operators, each operand shall have arithmetic type consistent with those - allowed by the corresponding binary operator. - Semantics -3 A compound assignment of the form E1 op = E2 is equivalent to the simple assignment - expression E1 = E1 op (E2), except that the lvalue E1 is evaluated only once, and with - respect to an indeterminately-sequenced function call, the operation of a compound - assignment is a single evaluation. If E1 has an _Atomic-qualified type, compound - assignment is a read-modify-write operation with memory_order_seq_cst memory - order semantics.112) - - - - -[page 103] - - 6.5.17 Comma operator - Syntax -1 expression: - assignment-expression - expression , assignment-expression - Semantics -2 The left operand of a comma operator is evaluated as a void expression; there is a - sequence point between its evaluation and that of the right operand. Then the right - operand is evaluated; the result has its type and value.113) -3 EXAMPLE As indicated by the syntax, the comma operator (as described in this subclause) cannot - appear in contexts where a comma is used to separate items in a list (such as arguments to functions or lists - of initializers). On the other hand, it can be used within a parenthesized expression or within the second - expression of a conditional operator in such contexts. In the function call - f(a, (t=3, t+2), c) - the function has three arguments, the second of which has the value 5. - - Forward references: initialization (6.7.9). - - - - - 112) Where a pointer to an atomic object can be formed, this is equivalent to the following code sequence - where T is the type of E1: - T tmp = E1; - T result; - do { - result = tmp op (E2); - } while (!atomic_compare_exchange_strong(&E1, &tmp, result)); - with result being the result of the operation. - 113) A comma operator does not yield an lvalue. - -[page 104] - - 6.6 Constant expressions - Syntax -1 constant-expression: - conditional-expression - Description -2 A constant expression can be evaluated during translation rather than runtime, and - accordingly may be used in any place that a constant may be. - Constraints -3 Constant expressions shall not contain assignment, increment, decrement, function-call, - or comma operators, except when they are contained within a subexpression that is not - evaluated.114) -4 Each constant expression shall evaluate to a constant that is in the range of representable - values for its type. - Semantics -5 An expression that evaluates to a constant is required in several contexts. If a floating - expression is evaluated in the translation environment, the arithmetic precision and range - shall be at least as great as if the expression were being evaluated in the execution - environment.115) -6 An integer constant expression116) shall have integer type and shall only have operands - that are integer constants, enumeration constants, character constants, sizeof - expressions whose results are integer constants, and floating constants that are the - immediate operands of casts. Cast operators in an integer constant expression shall only - convert arithmetic types to integer types, except as part of an operand to the sizeof - operator. -7 More latitude is permitted for constant expressions in initializers. Such a constant - expression shall be, or evaluate to, one of the following: - -- an arithmetic constant expression, - - - - 114) The operand of a sizeof operator is usually not evaluated (6.5.3.4). - 115) The use of evaluation formats as characterized by FLT_EVAL_METHOD also applies to evaluation in - the translation environment. - 116) An integer constant expression is required in a number of contexts such as the size of a bit-field - member of a structure, the value of an enumeration constant, and the size of a non-variable length - array. Further constraints that apply to the integer constant expressions used in conditional-inclusion - preprocessing directives are discussed in 6.10.1. - -[page 105] - - -- a null pointer constant, - -- an address constant, or - -- an address constant for a complete object type plus or minus an integer constant - expression. -8 An arithmetic constant expression shall have arithmetic type and shall only have - operands that are integer constants, floating constants, enumeration constants, character - constants, and sizeof expressions. Cast operators in an arithmetic constant expression - shall only convert arithmetic types to arithmetic types, except as part of an operand to a - sizeof operator whose result is an integer constant. -9 An address constant is a null pointer, a pointer to an lvalue designating an object of static - storage duration, or a pointer to a function designator; it shall be created explicitly using - the unary & operator or an integer constant cast to pointer type, or implicitly by the use of - an expression of array or function type. The array-subscript [] and member-access . - and -> operators, the address & and indirection * unary operators, and pointer casts may - be used in the creation of an address constant, but the value of an object shall not be - accessed by use of these operators. -10 An implementation may accept other forms of constant expressions. -11 The semantic rules for the evaluation of a constant expression are the same as for - nonconstant expressions.117) - Forward references: array declarators (6.7.6.2), initialization (6.7.9). - - - - - 117) Thus, in the following initialization, - static int i = 2 || 1 / 0; - the expression is a valid integer constant expression with value one. - -[page 106] - - 6.7 Declarations - Syntax -1 declaration: - declaration-specifiers init-declarator-listopt ; - static_assert-declaration * - declaration-specifiers: - storage-class-specifier declaration-specifiersopt - type-specifier declaration-specifiersopt - type-qualifier declaration-specifiersopt - function-specifier declaration-specifiersopt - alignment-specifier declaration-specifiersopt - init-declarator-list: - init-declarator - init-declarator-list , init-declarator - init-declarator: - declarator - declarator = initializer - Constraints -2 A declaration other than a static_assert declaration shall declare at least a declarator - (other than the parameters of a function or the members of a structure or union), a tag, or - the members of an enumeration. -3 If an identifier has no linkage, there shall be no more than one declaration of the identifier - (in a declarator or type specifier) with the same scope and in the same name space, except - that a typedef name can be redefined to denote the same type as it currently does and tags - may be redeclared as specified in 6.7.2.3. -4 All declarations in the same scope that refer to the same object or function shall specify - compatible types. - Semantics -5 A declaration specifies the interpretation and attributes of a set of identifiers. A definition - of an identifier is a declaration for that identifier that: - -- for an object, causes storage to be reserved for that object; - -- for a function, includes the function body;118) - - - - 118) Function definitions have a different syntax, described in 6.9.1. - -[page 107] - - -- for an enumeration constant or typedef name, is the (only) declaration of the - identifier. -6 The declaration specifiers consist of a sequence of specifiers that indicate the linkage, - storage duration, and part of the type of the entities that the declarators denote. The init- - declarator-list is a comma-separated sequence of declarators, each of which may have - additional type information, or an initializer, or both. The declarators contain the - identifiers (if any) being declared. -7 If an identifier for an object is declared with no linkage, the type for the object shall be * - complete by the end of its declarator, or by the end of its init-declarator if it has an - initializer; in the case of function parameters (including in prototypes), it is the adjusted - type (see 6.7.6.3) that is required to be complete. - Forward references: declarators (6.7.6), enumeration specifiers (6.7.2.2), initialization - (6.7.9), type names (6.7.7), type qualifiers (6.7.3). - 6.7.1 Storage-class specifiers - Syntax -1 storage-class-specifier: - typedef - extern - static - _Thread_local - auto - register - Constraints -2 At most, one storage-class specifier may be given in the declaration specifiers in a - declaration, except that _Thread_local may appear with static or extern.119) -3 In the declaration of an object with block scope, if the declaration specifiers include - _Thread_local, they shall also include either static or extern. If - _Thread_local appears in any declaration of an object, it shall be present in every - declaration of that object. - Semantics -4 The typedef specifier is called a ''storage-class specifier'' for syntactic convenience - only; it is discussed in 6.7.8. The meanings of the various linkages and storage durations - were discussed in 6.2.2 and 6.2.4. - - - - 119) See ''future language directions'' (6.11.5). - -[page 108] - -5 A declaration of an identifier for an object with storage-class specifier register - suggests that access to the object be as fast as possible. The extent to which such - suggestions are effective is implementation-defined.120) -6 The declaration of an identifier for a function that has block scope shall have no explicit - storage-class specifier other than extern. -7 If an aggregate or union object is declared with a storage-class specifier other than - typedef, the properties resulting from the storage-class specifier, except with respect to - linkage, also apply to the members of the object, and so on recursively for any aggregate - or union member objects. - Forward references: type definitions (6.7.8). - 6.7.2 Type specifiers - Syntax -1 type-specifier: - void - char - short - int - long - float - double - signed - unsigned - _Bool - _Complex - _Atomic ( type-name ) - struct-or-union-specifier - enum-specifier - typedef-name - Constraints -2 At least one type specifier shall be given in the declaration specifiers in each declaration, - and in the specifier-qualifier list in each struct declaration and type name. Each list of - - - 120) The implementation may treat any register declaration simply as an auto declaration. However, - whether or not addressable storage is actually used, the address of any part of an object declared with - storage-class specifier register cannot be computed, either explicitly (by use of the unary & - operator as discussed in 6.5.3.2) or implicitly (by converting an array name to a pointer as discussed in - 6.3.2.1). Thus, the only operator that can be applied to an array declared with storage-class specifier - register is sizeof. - -[page 109] - - type specifiers shall be one of the following multisets (delimited by commas, when there - is more than one multiset per item); the type specifiers may occur in any order, possibly - intermixed with the other declaration specifiers. - -- void - -- char - -- signed char - -- unsigned char - -- short, signed short, short int, or signed short int - -- unsigned short, or unsigned short int - -- int, signed, or signed int - -- unsigned, or unsigned int - -- long, signed long, long int, or signed long int - -- unsigned long, or unsigned long int - -- long long, signed long long, long long int, or - signed long long int - -- unsigned long long, or unsigned long long int - -- float - -- double - -- long double - -- _Bool - -- float _Complex - -- double _Complex - -- long double _Complex - -- _Atomic ( type-name ) - -- struct or union specifier - -- enum specifier - -- typedef name -3 The type specifier _Complex shall not be used if the implementation does not support - complex types; likewise, _Atomic shall not be used if the implementation does not - support atomic types (see 6.10.8.3). - - - -[page 110] - - Semantics -4 The _Atomic form of type specifier designates the _Atomic-qualified version of the - named type. -5 Specifiers for structures, unions, and enumerations are discussed in 6.7.2.1 through - 6.7.2.3. Declarations of typedef names are discussed in 6.7.8. The characteristics of the - other types are discussed in 6.2.5. -6 Each of the comma-separated multisets designates the same type, except that for bit- - fields, it is implementation-defined whether the specifier int designates the same type as - signed int or the same type as unsigned int. - Forward references: enumeration specifiers (6.7.2.2), structure and union specifiers - (6.7.2.1), tags (6.7.2.3), type definitions (6.7.8). - 6.7.2.1 Structure and union specifiers - Syntax -1 struct-or-union-specifier: - struct-or-union identifieropt { struct-declaration-list } - struct-or-union identifier - struct-or-union: - struct - union - struct-declaration-list: - struct-declaration - struct-declaration-list struct-declaration - struct-declaration: - specifier-qualifier-list struct-declarator-listopt ; - static_assert-declaration - specifier-qualifier-list: - type-specifier specifier-qualifier-listopt - type-qualifier specifier-qualifier-listopt - struct-declarator-list: - struct-declarator - struct-declarator-list , struct-declarator - struct-declarator: - declarator - declaratoropt : constant-expression - - - -[page 111] - - Constraints -2 A struct-declaration that does not declare an anonymous structure or anonymous union - shall contain a struct-declarator-list. -3 A structure or union shall not contain a member with incomplete or function type (hence, - a structure shall not contain an instance of itself, but may contain a pointer to an instance - of itself), except that the last member of a structure with more than one named member - may have incomplete array type; such a structure (and any union containing, possibly - recursively, a member that is such a structure) shall not be a member of a structure or an - element of an array. -4 The expression that specifies the width of a bit-field shall be an integer constant - expression with a nonnegative value that does not exceed the width of an object of the - type that would be specified were the colon and expression omitted.121) If the value is - zero, the declaration shall have no declarator. -5 A bit-field shall have a type that is a qualified or unqualified version of _Bool, signed - int, unsigned int, or some other implementation-defined type. - Semantics -6 As discussed in 6.2.5, a structure is a type consisting of a sequence of members, whose - storage is allocated in an ordered sequence, and a union is a type consisting of a sequence - of members whose storage overlap. -7 Structure and union specifiers have the same form. The keywords struct and union - indicate that the type being specified is, respectively, a structure type or a union type. -8 The presence of a struct-declaration-list in a struct-or-union-specifier declares a new type, - within a translation unit. The struct-declaration-list is a sequence of declarations for the - members of the structure or union. If the struct-declaration-list contains no named - members, no anonymous structures, and no anonymous unions, the behavior is undefined. - The type is incomplete until immediately after the } that terminates the list, and complete - thereafter. -9 A member of a structure or union may have any complete object type other than a - variably modified type.122) In addition, a member may be declared to consist of a - specified number of bits (including a sign bit, if any). Such a member is called a - bit-field;123) its width is preceded by a colon. - - - - 121) While the number of bits in a _Bool object is at least CHAR_BIT, the width (number of sign and - value bits) of a _Bool may be just 1 bit. - 122) A structure or union cannot contain a member with a variably modified type because member names - are not ordinary identifiers as defined in 6.2.3. - -[page 112] - -10 A bit-field is interpreted as a signed or unsigned integer type consisting of the specified - number of bits.124) If the value 0 or 1 is stored into a nonzero-width bit-field of type - _Bool, the value of the bit-field shall compare equal to the value stored; a _Bool bit- - field has the semantics of a _Bool. -11 An implementation may allocate any addressable storage unit large enough to hold a bit- - field. If enough space remains, a bit-field that immediately follows another bit-field in a - structure shall be packed into adjacent bits of the same unit. If insufficient space remains, - whether a bit-field that does not fit is put into the next unit or overlaps adjacent units is - implementation-defined. The order of allocation of bit-fields within a unit (high-order to - low-order or low-order to high-order) is implementation-defined. The alignment of the - addressable storage unit is unspecified. -12 A bit-field declaration with no declarator, but only a colon and a width, indicates an - unnamed bit-field.125) As a special case, a bit-field structure member with a width of 0 - indicates that no further bit-field is to be packed into the unit in which the previous bit- - field, if any, was placed. -13 An unnamed member of structure type with no tag is called an anonymous structure; an - unnamed member of union type with no tag is called an anonymous union. The members - of an anonymous structure or union are considered to be members of the containing - structure or union. This applies recursively if the containing structure or union is also - anonymous. -14 Each non-bit-field member of a structure or union object is aligned in an implementation- - defined manner appropriate to its type. -15 Within a structure object, the non-bit-field members and the units in which bit-fields - reside have addresses that increase in the order in which they are declared. A pointer to a - structure object, suitably converted, points to its initial member (or if that member is a - bit-field, then to the unit in which it resides), and vice versa. There may be unnamed - padding within a structure object, but not at its beginning. -16 The size of a union is sufficient to contain the largest of its members. The value of at - most one of the members can be stored in a union object at any time. A pointer to a - union object, suitably converted, points to each of its members (or if a member is a bit- - field, then to the unit in which it resides), and vice versa. - - - 123) The unary & (address-of) operator cannot be applied to a bit-field object; thus, there are no pointers to - or arrays of bit-field objects. - 124) As specified in 6.7.2 above, if the actual type specifier used is int or a typedef-name defined as int, - then it is implementation-defined whether the bit-field is signed or unsigned. - 125) An unnamed bit-field structure member is useful for padding to conform to externally imposed - layouts. - -[page 113] - -17 There may be unnamed padding at the end of a structure or union. -18 As a special case, the last element of a structure with more than one named member may - have an incomplete array type; this is called a flexible array member. In most situations, - the flexible array member is ignored. In particular, the size of the structure is as if the - flexible array member were omitted except that it may have more trailing padding than - the omission would imply. However, when a . (or ->) operator has a left operand that is - (a pointer to) a structure with a flexible array member and the right operand names that - member, it behaves as if that member were replaced with the longest array (with the same - element type) that would not make the structure larger than the object being accessed; the - offset of the array shall remain that of the flexible array member, even if this would differ - from that of the replacement array. If this array would have no elements, it behaves as if - it had one element but the behavior is undefined if any attempt is made to access that - element or to generate a pointer one past it. -19 EXAMPLE 1 The following illustrates anonymous structures and unions: - struct v { - union { // anonymous union - struct { int i, j; }; // anonymous structure - struct { long k, l; } w; - }; - int m; - } v1; - v1.i = 2; // valid - v1.k = 3; // invalid: inner structure is not anonymous - v1.w.k = 5; // valid - -20 EXAMPLE 2 After the declaration: - struct s { int n; double d[]; }; - the structure struct s has a flexible array member d. A typical way to use this is: - int m = /* some value */; - struct s *p = malloc(sizeof (struct s) + sizeof (double [m])); - and assuming that the call to malloc succeeds, the object pointed to by p behaves, for most purposes, as if - p had been declared as: - struct { int n; double d[m]; } *p; - (there are circumstances in which this equivalence is broken; in particular, the offsets of member d might - not be the same). -21 Following the above declaration: - struct s t1 = { 0 }; // valid - struct s t2 = { 1, { 4.2 }}; // invalid - t1.n = 4; // valid - t1.d[0] = 4.2; // might be undefined behavior - The initialization of t2 is invalid (and violates a constraint) because struct s is treated as if it did not - contain member d. The assignment to t1.d[0] is probably undefined behavior, but it is possible that - -[page 114] - - sizeof (struct s) >= offsetof(struct s, d) + sizeof (double) - in which case the assignment would be legitimate. Nevertheless, it cannot appear in strictly conforming - code. -22 After the further declaration: - struct ss { int n; }; - the expressions: - sizeof (struct s) >= sizeof (struct ss) - sizeof (struct s) >= offsetof(struct s, d) - are always equal to 1. -23 If sizeof (double) is 8, then after the following code is executed: - struct s *s1; - struct s *s2; - s1 = malloc(sizeof (struct s) + 64); - s2 = malloc(sizeof (struct s) + 46); - and assuming that the calls to malloc succeed, the objects pointed to by s1 and s2 behave, for most - purposes, as if the identifiers had been declared as: - struct { int n; double d[8]; } *s1; - struct { int n; double d[5]; } *s2; -24 Following the further successful assignments: - s1 = malloc(sizeof (struct s) + 10); - s2 = malloc(sizeof (struct s) + 6); - they then behave as if the declarations were: - struct { int n; double d[1]; } *s1, *s2; - and: - double *dp; - dp = &(s1->d[0]); // valid - *dp = 42; // valid - dp = &(s2->d[0]); // valid - *dp = 42; // undefined behavior -25 The assignment: - *s1 = *s2; - only copies the member n; if any of the array elements are within the first sizeof (struct s) bytes - of the structure, they might be copied or simply overwritten with indeterminate values. - - Forward references: declarators (6.7.6), tags (6.7.2.3). - - - - -[page 115] - - 6.7.2.2 Enumeration specifiers - Syntax -1 enum-specifier: - enum identifieropt { enumerator-list } - enum identifieropt { enumerator-list , } - enum identifier - enumerator-list: - enumerator - enumerator-list , enumerator - enumerator: - enumeration-constant - enumeration-constant = constant-expression - Constraints -2 The expression that defines the value of an enumeration constant shall be an integer - constant expression that has a value representable as an int. - Semantics -3 The identifiers in an enumerator list are declared as constants that have type int and - may appear wherever such are permitted.126) An enumerator with = defines its - enumeration constant as the value of the constant expression. If the first enumerator has - no =, the value of its enumeration constant is 0. Each subsequent enumerator with no = - defines its enumeration constant as the value of the constant expression obtained by - adding 1 to the value of the previous enumeration constant. (The use of enumerators with - = may produce enumeration constants with values that duplicate other values in the same - enumeration.) The enumerators of an enumeration are also known as its members. -4 Each enumerated type shall be compatible with char, a signed integer type, or an - unsigned integer type. The choice of type is implementation-defined,127) but shall be - capable of representing the values of all the members of the enumeration. The - enumerated type is incomplete until immediately after the } that terminates the list of - enumerator declarations, and complete thereafter. - - - - - 126) Thus, the identifiers of enumeration constants declared in the same scope shall all be distinct from - each other and from other identifiers declared in ordinary declarators. - 127) An implementation may delay the choice of which integer type until all enumeration constants have - been seen. - -[page 116] - -5 EXAMPLE The following fragment: - enum hue { chartreuse, burgundy, claret=20, winedark }; - enum hue col, *cp; - col = claret; - cp = &col; - if (*cp != burgundy) - /* ... */ - makes hue the tag of an enumeration, and then declares col as an object that has that type and cp as a - pointer to an object that has that type. The enumerated values are in the set { 0, 1, 20, 21 }. - - Forward references: tags (6.7.2.3). - 6.7.2.3 Tags - Constraints -1 A specific type shall have its content defined at most once. -2 Where two declarations that use the same tag declare the same type, they shall both use - the same choice of struct, union, or enum. -3 A type specifier of the form - enum identifier - without an enumerator list shall only appear after the type it specifies is complete. - Semantics -4 All declarations of structure, union, or enumerated types that have the same scope and - use the same tag declare the same type. Irrespective of whether there is a tag or what - other declarations of the type are in the same translation unit, the type is incomplete128) - until immediately after the closing brace of the list defining the content, and complete - thereafter. -5 Two declarations of structure, union, or enumerated types which are in different scopes or - use different tags declare distinct types. Each declaration of a structure, union, or - enumerated type which does not include a tag declares a distinct type. -6 A type specifier of the form - - - - - 128) An incomplete type may only by used when the size of an object of that type is not needed. It is not - needed, for example, when a typedef name is declared to be a specifier for a structure or union, or - when a pointer to or a function returning a structure or union is being declared. (See incomplete types - in 6.2.5.) The specification has to be complete before such a function is called or defined. - -[page 117] - - struct-or-union identifieropt { struct-declaration-list } - or - enum identifieropt { enumerator-list } - or - enum identifieropt { enumerator-list , } - declares a structure, union, or enumerated type. The list defines the structure content, - union content, or enumeration content. If an identifier is provided,129) the type specifier - also declares the identifier to be the tag of that type. -7 A declaration of the form - struct-or-union identifier ; - specifies a structure or union type and declares the identifier as a tag of that type.130) -8 If a type specifier of the form - struct-or-union identifier - occurs other than as part of one of the above forms, and no other declaration of the - identifier as a tag is visible, then it declares an incomplete structure or union type, and - declares the identifier as the tag of that type.130) -9 If a type specifier of the form - struct-or-union identifier - or - enum identifier - occurs other than as part of one of the above forms, and a declaration of the identifier as a - tag is visible, then it specifies the same type as that other declaration, and does not - redeclare the tag. -10 EXAMPLE 1 This mechanism allows declaration of a self-referential structure. - struct tnode { - int count; - struct tnode *left, *right; - }; - specifies a structure that contains an integer and two pointers to objects of the same type. Once this - declaration has been given, the declaration - - - - - 129) If there is no identifier, the type can, within the translation unit, only be referred to by the declaration - of which it is a part. Of course, when the declaration is of a typedef name, subsequent declarations - can make use of that typedef name to declare objects having the specified structure, union, or - enumerated type. - 130) A similar construction with enum does not exist. - -[page 118] - - struct tnode s, *sp; - declares s to be an object of the given type and sp to be a pointer to an object of the given type. With - these declarations, the expression sp->left refers to the left struct tnode pointer of the object to - which sp points; the expression s.right->count designates the count member of the right struct - tnode pointed to from s. -11 The following alternative formulation uses the typedef mechanism: - typedef struct tnode TNODE; - struct tnode { - int count; - TNODE *left, *right; - }; - TNODE s, *sp; - -12 EXAMPLE 2 To illustrate the use of prior declaration of a tag to specify a pair of mutually referential - structures, the declarations - struct s1 { struct s2 *s2p; /* ... */ }; // D1 - struct s2 { struct s1 *s1p; /* ... */ }; // D2 - specify a pair of structures that contain pointers to each other. Note, however, that if s2 were already - declared as a tag in an enclosing scope, the declaration D1 would refer to it, not to the tag s2 declared in - D2. To eliminate this context sensitivity, the declaration - struct s2; - may be inserted ahead of D1. This declares a new tag s2 in the inner scope; the declaration D2 then - completes the specification of the new type. - - Forward references: declarators (6.7.6), type definitions (6.7.8). - 6.7.3 Type qualifiers - Syntax -1 type-qualifier: - const - restrict - volatile - _Atomic - Constraints -2 Types other than pointer types whose referenced type is an object type shall not be - restrict-qualified. - Semantics -3 The properties associated with qualified types are meaningful only for expressions that - are lvalues.131) -4 If the same qualifier appears more than once in the same specifier-qualifier-list, either - directly or via one or more typedefs, the behavior is the same as if it appeared only - once. -[page 119] - -5 If an attempt is made to modify an object defined with a const-qualified type through use - of an lvalue with non-const-qualified type, the behavior is undefined. If an attempt is - made to refer to an object defined with a volatile-qualified type through use of an lvalue - with non-volatile-qualified type, the behavior is undefined.132) If an attempt is made to - refer to an object defined with an _Atomic-qualified type through use of an lvalue with - non-_Atomic-qualified type, the behavior is undefined. -6 An object that has volatile-qualified type may be modified in ways unknown to the - implementation or have other unknown side effects. Therefore any expression referring - to such an object shall be evaluated strictly according to the rules of the abstract machine, - as described in 5.1.2.3. Furthermore, at every sequence point the value last stored in the - object shall agree with that prescribed by the abstract machine, except as modified by the - unknown factors mentioned previously.133) What constitutes an access to an object that - has volatile-qualified type is implementation-defined. -7 An object that is accessed through a restrict-qualified pointer has a special association - with that pointer. This association, defined in 6.7.3.1 below, requires that all accesses to - that object use, directly or indirectly, the value of that particular pointer.134) The intended - use of the restrict qualifier (like the register storage class) is to promote - optimization, and deleting all instances of the qualifier from all preprocessing translation - units composing a conforming program does not change its meaning (i.e., observable - behavior). -8 If the specification of an array type includes any type qualifiers, the element type is so- - qualified, not the array type. If the specification of a function type includes any type - qualifiers, the behavior is undefined.135) -9 For two qualified types to be compatible, both shall have the identically qualified version - of a compatible type; the order of type qualifiers within a list of specifiers or qualifiers - does not affect the specified type. - - 131) The implementation may place a const object that is not volatile in a read-only region of - storage. Moreover, the implementation need not allocate storage for such an object if its address is - never used. - 132) This applies to those objects that behave as if they were defined with qualified types, even if they are - never actually defined as objects in the program (such as an object at a memory-mapped input/output - address). - 133) A volatile declaration may be used to describe an object corresponding to a memory-mapped - input/output port or an object accessed by an asynchronously interrupting function. Actions on - objects so declared shall not be ''optimized out'' by an implementation or reordered except as - permitted by the rules for evaluating expressions. - 134) For example, a statement that assigns a value returned by malloc to a single pointer establishes this - association between the allocated object and the pointer. - 135) Both of these can occur through the use of typedefs. - -[page 120] - -10 EXAMPLE 1 An object declared - extern const volatile int real_time_clock; - may be modifiable by hardware, but cannot be assigned to, incremented, or decremented. - -11 EXAMPLE 2 The following declarations and expressions illustrate the behavior when type qualifiers - modify an aggregate type: - const struct s { int mem; } cs = { 1 }; - struct s ncs; // the object ncs is modifiable - typedef int A[2][3]; - const A a = {{4, 5, 6}, {7, 8, 9}}; // array of array of const int - int *pi; - const int *pci; - ncs = cs; // valid - cs = ncs; // violates modifiable lvalue constraint for = - pi = &ncs.mem; // valid - pi = &cs.mem; // violates type constraints for = - pci = &cs.mem; // valid - pi = a[0]; // invalid: a[0] has type ''const int *'' - - 6.7.3.1 Formal definition of restrict -1 Let D be a declaration of an ordinary identifier that provides a means of designating an - object P as a restrict-qualified pointer to type T. -2 If D appears inside a block and does not have storage class extern, let B denote the - block. If D appears in the list of parameter declarations of a function definition, let B - denote the associated block. Otherwise, let B denote the block of main (or the block of - whatever function is called at program startup in a freestanding environment). -3 In what follows, a pointer expression E is said to be based on object P if (at some - sequence point in the execution of B prior to the evaluation of E) modifying P to point to - a copy of the array object into which it formerly pointed would change the value of E.136) - Note that ''based'' is defined only for expressions with pointer types. -4 During each execution of B, let L be any lvalue that has &L based on P. If L is used to - access the value of the object X that it designates, and X is also modified (by any means), - then the following requirements apply: T shall not be const-qualified. Every other lvalue - used to access the value of X shall also have its address based on P. Every access that - modifies X shall be considered also to modify P, for the purposes of this subclause. If P - is assigned the value of a pointer expression E that is based on another restricted pointer - object P2, associated with block B2, then either the execution of B2 shall begin before - - - 136) In other words, E depends on the value of P itself rather than on the value of an object referenced - indirectly through P. For example, if identifier p has type (int **restrict), then the pointer - expressions p and p+1 are based on the restricted pointer object designated by p, but the pointer - expressions *p and p[1] are not. - -[page 121] - - the execution of B, or the execution of B2 shall end prior to the assignment. If these - requirements are not met, then the behavior is undefined. -5 Here an execution of B means that portion of the execution of the program that would - correspond to the lifetime of an object with scalar type and automatic storage duration - associated with B. -6 A translator is free to ignore any or all aliasing implications of uses of restrict. -7 EXAMPLE 1 The file scope declarations - int * restrict a; - int * restrict b; - extern int c[]; - assert that if an object is accessed using one of a, b, or c, and that object is modified anywhere in the - program, then it is never accessed using either of the other two. - -8 EXAMPLE 2 The function parameter declarations in the following example - void f(int n, int * restrict p, int * restrict q) - { - while (n-- > 0) - *p++ = *q++; - } - assert that, during each execution of the function, if an object is accessed through one of the pointer - parameters, then it is not also accessed through the other. -9 The benefit of the restrict qualifiers is that they enable a translator to make an effective dependence - analysis of function f without examining any of the calls of f in the program. The cost is that the - programmer has to examine all of those calls to ensure that none give undefined behavior. For example, the - second call of f in g has undefined behavior because each of d[1] through d[49] is accessed through - both p and q. - void g(void) - { - extern int d[100]; - f(50, d + 50, d); // valid - f(50, d + 1, d); // undefined behavior - } - -10 EXAMPLE 3 The function parameter declarations - void h(int n, int * restrict p, int * restrict q, int * restrict r) - { - int i; - for (i = 0; i < n; i++) - p[i] = q[i] + r[i]; - } - illustrate how an unmodified object can be aliased through two restricted pointers. In particular, if a and b - are disjoint arrays, a call of the form h(100, a, b, b) has defined behavior, because array b is not - modified within function h. - -11 EXAMPLE 4 The rule limiting assignments between restricted pointers does not distinguish between a - function call and an equivalent nested block. With one exception, only ''outer-to-inner'' assignments - -[page 122] - - between restricted pointers declared in nested blocks have defined behavior. - { - int * restrict p1; - int * restrict q1; - p1 = q1; // undefined behavior - { - int * restrict p2 = p1; // valid - int * restrict q2 = q1; // valid - p1 = q2; // undefined behavior - p2 = q2; // undefined behavior - } - } -12 The one exception allows the value of a restricted pointer to be carried out of the block in which it (or, more - precisely, the ordinary identifier used to designate it) is declared when that block finishes execution. For - example, this permits new_vector to return a vector. - typedef struct { int n; float * restrict v; } vector; - vector new_vector(int n) - { - vector t; - t.n = n; - t.v = malloc(n * sizeof (float)); - return t; - } - - 6.7.4 Function specifiers - Syntax -1 function-specifier: - inline - _Noreturn - Constraints -2 Function specifiers shall be used only in the declaration of an identifier for a function. -3 An inline definition of a function with external linkage shall not contain a definition of a - modifiable object with static or thread storage duration, and shall not contain a reference - to an identifier with internal linkage. -4 In a hosted environment, no function specifier(s) shall appear in a declaration of main. - Semantics -5 A function specifier may appear more than once; the behavior is the same as if it - appeared only once. -6 A function declared with an inline function specifier is an inline function. Making a - function an inline function suggests that calls to the function be as fast as possible.137) - The extent to which such suggestions are effective is implementation-defined.138) - -[page 123] - -7 Any function with internal linkage can be an inline function. For a function with external - linkage, the following restrictions apply: If a function is declared with an inline - function specifier, then it shall also be defined in the same translation unit. If all of the - file scope declarations for a function in a translation unit include the inline function - specifier without extern, then the definition in that translation unit is an inline - definition. An inline definition does not provide an external definition for the function, - and does not forbid an external definition in another translation unit. An inline definition - provides an alternative to an external definition, which a translator may use to implement - any call to the function in the same translation unit. It is unspecified whether a call to the - function uses the inline definition or the external definition.139) -8 A function declared with a _Noreturn function specifier shall not return to its caller. - Recommended practice -9 The implementation should produce a diagnostic message for a function declared with a - _Noreturn function specifier that appears to be capable of returning to its caller. -10 EXAMPLE 1 The declaration of an inline function with external linkage can result in either an external - definition, or a definition available for use only within the translation unit. A file scope declaration with - extern creates an external definition. The following example shows an entire translation unit. - inline double fahr(double t) - { - return (9.0 * t) / 5.0 + 32.0; - } - inline double cels(double t) - { - return (5.0 * (t - 32.0)) / 9.0; - } - extern double fahr(double); // creates an external definition - - - - - 137) By using, for example, an alternative to the usual function call mechanism, such as ''inline - substitution''. Inline substitution is not textual substitution, nor does it create a new function. - Therefore, for example, the expansion of a macro used within the body of the function uses the - definition it had at the point the function body appears, and not where the function is called; and - identifiers refer to the declarations in scope where the body occurs. Likewise, the function has a - single address, regardless of the number of inline definitions that occur in addition to the external - definition. - 138) For example, an implementation might never perform inline substitution, or might only perform inline - substitutions to calls in the scope of an inline declaration. - 139) Since an inline definition is distinct from the corresponding external definition and from any other - corresponding inline definitions in other translation units, all corresponding objects with static storage - duration are also distinct in each of the definitions. - -[page 124] - - double convert(int is_fahr, double temp) - { - /* A translator may perform inline substitutions */ - return is_fahr ? cels(temp) : fahr(temp); - } -11 Note that the definition of fahr is an external definition because fahr is also declared with extern, but - the definition of cels is an inline definition. Because cels has external linkage and is referenced, an - external definition has to appear in another translation unit (see 6.9); the inline definition and the external - definition are distinct and either may be used for the call. - -12 EXAMPLE 2 - _Noreturn void f () { - abort(); // ok - } - _Noreturn void g (int i) { // causes undefined behavior if i <= 0 - if (i > 0) abort(); - } - - Forward references: function definitions (6.9.1). - 6.7.5 Alignment specifier - Syntax -1 alignment-specifier: - _Alignas ( type-name ) - _Alignas ( constant-expression ) - Constraints -2 An alignment attribute shall not be specified in a declaration of a typedef, or a bit-field, or - a function, or a parameter, or an object declared with the register storage-class - specifier. -3 The constant expression shall be an integer constant expression. It shall evaluate to a - valid fundamental alignment, or to a valid extended alignment supported by the - implementation in the context in which it appears, or to zero. -4 The combined effect of all alignment attributes in a declaration shall not specify an - alignment that is less strict than the alignment that would otherwise be required for the - type of the object or field being declared. - Semantics -5 The first form is equivalent to _Alignas(alignof(type-name)). -6 The alignment requirement of the declared object or field is taken to be the specified - alignment. An alignment specification of zero has no effect.140) When multiple - alignment specifiers occur in a declaration, the effective alignment requirement is the - strictest specified alignment. - -[page 125] - -7 If the definition of an object has an alignment specifier, any other declaration of that - object shall either specify equivalent alignment or have no alignment specifier. If the - definition of an object does not have an alignment specifier, any other declaration of that - object shall also have no alignment specifier. If declarations of an object in different - translation units have different alignment specifiers, the behavior is undefined. - 6.7.6 Declarators - Syntax -1 declarator: - pointeropt direct-declarator - direct-declarator: - identifier - ( declarator ) - direct-declarator [ type-qualifier-listopt assignment-expressionopt ] - direct-declarator [ static type-qualifier-listopt assignment-expression ] - direct-declarator [ type-qualifier-list static assignment-expression ] - direct-declarator [ type-qualifier-listopt * ] - direct-declarator ( parameter-type-list ) - direct-declarator ( identifier-listopt ) - pointer: - * type-qualifier-listopt - * type-qualifier-listopt pointer - type-qualifier-list: - type-qualifier - type-qualifier-list type-qualifier - parameter-type-list: - parameter-list - parameter-list , ... - parameter-list: - parameter-declaration - parameter-list , parameter-declaration - parameter-declaration: - declaration-specifiers declarator - declaration-specifiers abstract-declaratoropt - - - - 140) An alignment specification of zero also does not affect other alignment specifications in the same - declaration. - -[page 126] - - identifier-list: - identifier - identifier-list , identifier - Semantics -2 Each declarator declares one identifier, and asserts that when an operand of the same - form as the declarator appears in an expression, it designates a function or object with the - scope, storage duration, and type indicated by the declaration specifiers. -3 A full declarator is a declarator that is not part of another declarator. The end of a full - declarator is a sequence point. If, in the nested sequence of declarators in a full - declarator, there is a declarator specifying a variable length array type, the type specified - by the full declarator is said to be variably modified. Furthermore, any type derived by - declarator type derivation from a variably modified type is itself variably modified. -4 In the following subclauses, consider a declaration - T D1 - where T contains the declaration specifiers that specify a type T (such as int) and D1 is - a declarator that contains an identifier ident. The type specified for the identifier ident in - the various forms of declarator is described inductively using this notation. -5 If, in the declaration ''T D1'', D1 has the form - identifier - then the type specified for ident is T . -6 If, in the declaration ''T D1'', D1 has the form - ( D ) - then ident has the type specified by the declaration ''T D''. Thus, a declarator in - parentheses is identical to the unparenthesized declarator, but the binding of complicated - declarators may be altered by parentheses. - Implementation limits -7 As discussed in 5.2.4.1, an implementation may limit the number of pointer, array, and - function declarators that modify an arithmetic, structure, union, or void type, either - directly or via one or more typedefs. - Forward references: array declarators (6.7.6.2), type definitions (6.7.8). - - - - -[page 127] - - 6.7.6.1 Pointer declarators - Semantics -1 If, in the declaration ''T D1'', D1 has the form - * type-qualifier-listopt D - and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list - T '', then the type specified for ident is ''derived-declarator-type-list type-qualifier-list - pointer to T ''. For each type qualifier in the list, ident is a so-qualified pointer. -2 For two pointer types to be compatible, both shall be identically qualified and both shall - be pointers to compatible types. -3 EXAMPLE The following pair of declarations demonstrates the difference between a ''variable pointer - to a constant value'' and a ''constant pointer to a variable value''. - const int *ptr_to_constant; - int *const constant_ptr; - The contents of any object pointed to by ptr_to_constant shall not be modified through that pointer, - but ptr_to_constant itself may be changed to point to another object. Similarly, the contents of the - int pointed to by constant_ptr may be modified, but constant_ptr itself shall always point to the - same location. -4 The declaration of the constant pointer constant_ptr may be clarified by including a definition for the - type ''pointer to int''. - typedef int *int_ptr; - const int_ptr constant_ptr; - declares constant_ptr as an object that has type ''const-qualified pointer to int''. - - 6.7.6.2 Array declarators - Constraints -1 In addition to optional type qualifiers and the keyword static, the [ and ] may delimit - an expression or *. If they delimit an expression (which specifies the size of an array), the - expression shall have an integer type. If the expression is a constant expression, it shall - have a value greater than zero. The element type shall not be an incomplete or function - type. The optional type qualifiers and the keyword static shall appear only in a - declaration of a function parameter with an array type, and then only in the outermost - array type derivation. -2 An ordinary identifier (as defined in 6.2.3) that has a variably modified type shall have - either block scope and no linkage or function prototype scope. If an identifier is declared - to be an object with static or thread storage duration, it shall not have a variable length - array type. - - - - -[page 128] - - Semantics -3 If, in the declaration ''T D1'', D1 has one of the forms: - D[ type-qualifier-listopt assignment-expressionopt ] - D[ static type-qualifier-listopt assignment-expression ] - D[ type-qualifier-list static assignment-expression ] - D[ type-qualifier-listopt * ] - and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list - T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.141) - (See 6.7.6.3 for the meaning of the optional type qualifiers and the keyword static.) -4 If the size is not present, the array type is an incomplete type. If the size is * instead of - being an expression, the array type is a variable length array type of unspecified size, - which can only be used in declarations or type names with function prototype scope;142) - such arrays are nonetheless complete types. If the size is an integer constant expression - and the element type has a known constant size, the array type is not a variable length - array type; otherwise, the array type is a variable length array type. (Variable length - arrays are a conditional feature that implementations need not support; see 6.10.8.3.) -5 If the size is an expression that is not an integer constant expression: if it occurs in a - declaration at function prototype scope, it is treated as if it were replaced by *; otherwise, - each time it is evaluated it shall have a value greater than zero. The size of each instance - of a variable length array type does not change during its lifetime. Where a size - expression is part of the operand of a sizeof operator and changing the value of the - size expression would not affect the result of the operator, it is unspecified whether or not - the size expression is evaluated. -6 For two array types to be compatible, both shall have compatible element types, and if - both size specifiers are present, and are integer constant expressions, then both size - specifiers shall have the same constant value. If the two array types are used in a context - which requires them to be compatible, it is undefined behavior if the two size specifiers - evaluate to unequal values. -7 EXAMPLE 1 - float fa[11], *afp[17]; - declares an array of float numbers and an array of pointers to float numbers. - -8 EXAMPLE 2 Note the distinction between the declarations - - - - - 141) When several ''array of'' specifications are adjacent, a multidimensional array is declared. - 142) Thus, * can be used only in function declarations that are not definitions (see 6.7.6.3). - -[page 129] - - extern int *x; - extern int y[]; - The first declares x to be a pointer to int; the second declares y to be an array of int of unspecified size - (an incomplete type), the storage for which is defined elsewhere. - -9 EXAMPLE 3 The following declarations demonstrate the compatibility rules for variably modified types. - extern int n; - extern int m; - void fcompat(void) - { - int a[n][6][m]; - int (*p)[4][n+1]; - int c[n][n][6][m]; - int (*r)[n][n][n+1]; - p = a; // invalid: not compatible because 4 != 6 - r = c; // compatible, but defined behavior only if - // n == 6 and m == n+1 - } - -10 EXAMPLE 4 All declarations of variably modified (VM) types have to be at either block scope or - function prototype scope. Array objects declared with the _Thread_local, static, or extern - storage-class specifier cannot have a variable length array (VLA) type. However, an object declared with - the static storage-class specifier can have a VM type (that is, a pointer to a VLA type). Finally, all - identifiers declared with a VM type have to be ordinary identifiers and cannot, therefore, be members of - structures or unions. - extern int n; - int A[n]; // invalid: file scope VLA - extern int (*p2)[n]; // invalid: file scope VM - int B[100]; // valid: file scope but not VM - void fvla(int m, int C[m][m]); // valid: VLA with prototype scope - void fvla(int m, int C[m][m]) // valid: adjusted to auto pointer to VLA - { - typedef int VLA[m][m]; // valid: block scope typedef VLA - struct tag { - int (*y)[n]; // invalid: y not ordinary identifier - int z[n]; // invalid: z not ordinary identifier - }; - int D[m]; // valid: auto VLA - static int E[m]; // invalid: static block scope VLA - extern int F[m]; // invalid: F has linkage and is VLA - int (*s)[m]; // valid: auto pointer to VLA - extern int (*r)[m]; // invalid: r has linkage and points to VLA - static int (*q)[m] = &B; // valid: q is a static block pointer to VLA - } - - Forward references: function declarators (6.7.6.3), function definitions (6.9.1), - initialization (6.7.9). - - - -[page 130] - - 6.7.6.3 Function declarators (including prototypes) - Constraints -1 A function declarator shall not specify a return type that is a function type or an array - type. -2 The only storage-class specifier that shall occur in a parameter declaration is register. -3 An identifier list in a function declarator that is not part of a definition of that function - shall be empty. -4 After adjustment, the parameters in a parameter type list in a function declarator that is - part of a definition of that function shall not have incomplete type. - Semantics -5 If, in the declaration ''T D1'', D1 has the form - D( parameter-type-list ) - or - D( identifier-listopt ) - and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list - T '', then the type specified for ident is ''derived-declarator-type-list function returning - T ''. -6 A parameter type list specifies the types of, and may declare identifiers for, the - parameters of the function. -7 A declaration of a parameter as ''array of type'' shall be adjusted to ''qualified pointer to - type'', where the type qualifiers (if any) are those specified within the [ and ] of the - array type derivation. If the keyword static also appears within the [ and ] of the - array type derivation, then for each call to the function, the value of the corresponding - actual argument shall provide access to the first element of an array with at least as many - elements as specified by the size expression. -8 A declaration of a parameter as ''function returning type'' shall be adjusted to ''pointer to - function returning type'', as in 6.3.2.1. -9 If the list terminates with an ellipsis (, ...), no information about the number or types - of the parameters after the comma is supplied.143) -10 The special case of an unnamed parameter of type void as the only item in the list - specifies that the function has no parameters. - - - - 143) The macros defined in the header (7.16) may be used to access arguments that - correspond to the ellipsis. - -[page 131] - -11 If, in a parameter declaration, an identifier can be treated either as a typedef name or as a - parameter name, it shall be taken as a typedef name. -12 If the function declarator is not part of a definition of that function, parameters may have - incomplete type and may use the [*] notation in their sequences of declarator specifiers - to specify variable length array types. -13 The storage-class specifier in the declaration specifiers for a parameter declaration, if - present, is ignored unless the declared parameter is one of the members of the parameter - type list for a function definition. -14 An identifier list declares only the identifiers of the parameters of the function. An empty - list in a function declarator that is part of a definition of that function specifies that the - function has no parameters. The empty list in a function declarator that is not part of a - definition of that function specifies that no information about the number or types of the - parameters is supplied.144) -15 For two function types to be compatible, both shall specify compatible return types.145) - Moreover, the parameter type lists, if both are present, shall agree in the number of - parameters and in use of the ellipsis terminator; corresponding parameters shall have - compatible types. If one type has a parameter type list and the other type is specified by a - function declarator that is not part of a function definition and that contains an empty - identifier list, the parameter list shall not have an ellipsis terminator and the type of each - parameter shall be compatible with the type that results from the application of the - default argument promotions. If one type has a parameter type list and the other type is - specified by a function definition that contains a (possibly empty) identifier list, both shall - agree in the number of parameters, and the type of each prototype parameter shall be - compatible with the type that results from the application of the default argument - promotions to the type of the corresponding identifier. (In the determination of type - compatibility and of a composite type, each parameter declared with function or array - type is taken as having the adjusted type and each parameter declared with qualified type - is taken as having the unqualified version of its declared type.) -16 EXAMPLE 1 The declaration - int f(void), *fip(), (*pfi)(); - declares a function f with no parameters returning an int, a function fip with no parameter specification - returning a pointer to an int, and a pointer pfi to a function with no parameter specification returning an - int. It is especially useful to compare the last two. The binding of *fip() is *(fip()), so that the - declaration suggests, and the same construction in an expression requires, the calling of a function fip, - and then using indirection through the pointer result to yield an int. In the declarator (*pfi)(), the - extra parentheses are necessary to indicate that indirection through a pointer to a function yields a function - - - 144) See ''future language directions'' (6.11.6). - 145) If both function types are ''old style'', parameter types are not compared. - -[page 132] - - designator, which is then used to call the function; it returns an int. -17 If the declaration occurs outside of any function, the identifiers have file scope and external linkage. If the - declaration occurs inside a function, the identifiers of the functions f and fip have block scope and either - internal or external linkage (depending on what file scope declarations for these identifiers are visible), and - the identifier of the pointer pfi has block scope and no linkage. - -18 EXAMPLE 2 The declaration - int (*apfi[3])(int *x, int *y); - declares an array apfi of three pointers to functions returning int. Each of these functions has two - parameters that are pointers to int. The identifiers x and y are declared for descriptive purposes only and - go out of scope at the end of the declaration of apfi. - -19 EXAMPLE 3 The declaration - int (*fpfi(int (*)(long), int))(int, ...); - declares a function fpfi that returns a pointer to a function returning an int. The function fpfi has two - parameters: a pointer to a function returning an int (with one parameter of type long int), and an int. - The pointer returned by fpfi points to a function that has one int parameter and accepts zero or more - additional arguments of any type. - -20 EXAMPLE 4 The following prototype has a variably modified parameter. - void addscalar(int n, int m, - double a[n][n*m+300], double x); - int main() - { - double b[4][308]; - addscalar(4, 2, b, 2.17); - return 0; - } - void addscalar(int n, int m, - double a[n][n*m+300], double x) - { - for (int i = 0; i < n; i++) - for (int j = 0, k = n*m+300; j < k; j++) - // a is a pointer to a VLA with n*m+300 elements - a[i][j] += x; - } - -21 EXAMPLE 5 The following are all compatible function prototype declarators. - double maximum(int n, int m, double a[n][m]); - double maximum(int n, int m, double a[*][*]); - double maximum(int n, int m, double a[ ][*]); - double maximum(int n, int m, double a[ ][m]); - as are: - void f(double (* restrict a)[5]); - void f(double a[restrict][5]); - void f(double a[restrict 3][5]); - void f(double a[restrict static 3][5]); - - -[page 133] - - (Note that the last declaration also specifies that the argument corresponding to a in any call to f must be a - non-null pointer to the first of at least three arrays of 5 doubles, which the others do not.) - - Forward references: function definitions (6.9.1), type names (6.7.7). - 6.7.7 Type names - Syntax -1 type-name: - specifier-qualifier-list abstract-declaratoropt - abstract-declarator: - pointer - pointeropt direct-abstract-declarator - direct-abstract-declarator: - ( abstract-declarator ) - direct-abstract-declaratoropt [ type-qualifier-listopt - assignment-expressionopt ] - direct-abstract-declaratoropt [ static type-qualifier-listopt - assignment-expression ] - direct-abstract-declaratoropt [ type-qualifier-list static - assignment-expression ] - direct-abstract-declaratoropt [ * ] - direct-abstract-declaratoropt ( parameter-type-listopt ) - Semantics -2 In several contexts, it is necessary to specify a type. This is accomplished using a type - name, which is syntactically a declaration for a function or an object of that type that - omits the identifier.146) -3 EXAMPLE The constructions - (a) int - (b) int * - (c) int *[3] - (d) int (*)[3] - (e) int (*)[*] - (f) int *() - (g) int (*)(void) - (h) int (*const [])(unsigned int, ...) - name respectively the types (a) int, (b) pointer to int, (c) array of three pointers to int, (d) pointer to an - array of three ints, (e) pointer to a variable length array of an unspecified number of ints, (f) function - with no parameter specification returning a pointer to int, (g) pointer to function with no parameters - - - 146) As indicated by the syntax, empty parentheses in a type name are interpreted as ''function with no - parameter specification'', rather than redundant parentheses around the omitted identifier. - -[page 134] - - returning an int, and (h) array of an unspecified number of constant pointers to functions, each with one - parameter that has type unsigned int and an unspecified number of other parameters, returning an - int. - - 6.7.8 Type definitions - Syntax -1 typedef-name: - identifier - Constraints -2 If a typedef name specifies a variably modified type then it shall have block scope. - Semantics -3 In a declaration whose storage-class specifier is typedef, each declarator defines an - identifier to be a typedef name that denotes the type specified for the identifier in the way - described in 6.7.6. Any array size expressions associated with variable length array - declarators are evaluated each time the declaration of the typedef name is reached in the - order of execution. A typedef declaration does not introduce a new type, only a - synonym for the type so specified. That is, in the following declarations: - typedef T type_ident; - type_ident D; - type_ident is defined as a typedef name with the type specified by the declaration - specifiers in T (known as T ), and the identifier in D has the type ''derived-declarator- - type-list T '' where the derived-declarator-type-list is specified by the declarators of D. A - typedef name shares the same name space as other identifiers declared in ordinary - declarators. -4 EXAMPLE 1 After - typedef int MILES, KLICKSP(); - typedef struct { double hi, lo; } range; - the constructions - MILES distance; - extern KLICKSP *metricp; - range x; - range z, *zp; - are all valid declarations. The type of distance is int, that of metricp is ''pointer to function with no - parameter specification returning int'', and that of x and z is the specified structure; zp is a pointer to - such a structure. The object distance has a type compatible with any other int object. - -5 EXAMPLE 2 After the declarations - typedef struct s1 { int x; } t1, *tp1; - typedef struct s2 { int x; } t2, *tp2; - type t1 and the type pointed to by tp1 are compatible. Type t1 is also compatible with type struct - -[page 135] - - s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int. - -6 EXAMPLE 3 The following obscure constructions - typedef signed int t; - typedef int plain; - struct tag { - unsigned t:4; - const t:5; - plain r:5; - }; - declare a typedef name t with type signed int, a typedef name plain with type int, and a structure - with three bit-field members, one named t that contains values in the range [0, 15], an unnamed const- - qualified bit-field which (if it could be accessed) would contain values in either the range [-15, +15] or - [-16, +15], and one named r that contains values in one of the ranges [0, 31], [-15, +15], or [-16, +15]. - (The choice of range is implementation-defined.) The first two bit-field declarations differ in that - unsigned is a type specifier (which forces t to be the name of a structure member), while const is a - type qualifier (which modifies t which is still visible as a typedef name). If these declarations are followed - in an inner scope by - t f(t (t)); - long t; - then a function f is declared with type ''function returning signed int with one unnamed parameter - with type pointer to function returning signed int with one unnamed parameter with type signed - int'', and an identifier t with type long int. - -7 EXAMPLE 4 On the other hand, typedef names can be used to improve code readability. All three of the - following declarations of the signal function specify exactly the same type, the first without making use - of any typedef names. - typedef void fv(int), (*pfv)(int); - void (*signal(int, void (*)(int)))(int); - fv *signal(int, fv *); - pfv signal(int, pfv); - -8 EXAMPLE 5 If a typedef name denotes a variable length array type, the length of the array is fixed at the - time the typedef name is defined, not each time it is used: - void copyt(int n) - { - typedef int B[n]; // B is n ints, n evaluated now - n += 1; - B a; // a is n ints, n without += 1 - int b[n]; // a and b are different sizes - for (int i = 1; i < n; i++) - a[i-1] = b[i]; - } - - - - -[page 136] - - 6.7.9 Initialization - Syntax -1 initializer: - assignment-expression - { initializer-list } - { initializer-list , } - initializer-list: - designationopt initializer - initializer-list , designationopt initializer - designation: - designator-list = - designator-list: - designator - designator-list designator - designator: - [ constant-expression ] - . identifier - Constraints -2 No initializer shall attempt to provide a value for an object not contained within the entity - being initialized. -3 The type of the entity to be initialized shall be an array of unknown size or a complete - object type that is not a variable length array type. -4 All the expressions in an initializer for an object that has static or thread storage duration - shall be constant expressions or string literals. -5 If the declaration of an identifier has block scope, and the identifier has external or - internal linkage, the declaration shall have no initializer for the identifier. -6 If a designator has the form - [ constant-expression ] - then the current object (defined below) shall have array type and the expression shall be - an integer constant expression. If the array is of unknown size, any nonnegative value is - valid. -7 If a designator has the form - . identifier - then the current object (defined below) shall have structure or union type and the - identifier shall be the name of a member of that type. -[page 137] - - Semantics -8 An initializer specifies the initial value stored in an object. -9 Except where explicitly stated otherwise, for the purposes of this subclause unnamed - members of objects of structure and union type do not participate in initialization. - Unnamed members of structure objects have indeterminate value even after initialization. -10 If an object that has automatic storage duration is not initialized explicitly, its value is - indeterminate. If an object that has static or thread storage duration is not initialized - explicitly, then: - -- if it has pointer type, it is initialized to a null pointer; - -- if it has arithmetic type, it is initialized to (positive or unsigned) zero; - -- if it is an aggregate, every member is initialized (recursively) according to these rules, - and any padding is initialized to zero bits; - -- if it is a union, the first named member is initialized (recursively) according to these - rules, and any padding is initialized to zero bits; -11 The initializer for a scalar shall be a single expression, optionally enclosed in braces. The - initial value of the object is that of the expression (after conversion); the same type - constraints and conversions as for simple assignment apply, taking the type of the scalar - to be the unqualified version of its declared type. -12 The rest of this subclause deals with initializers for objects that have aggregate or union - type. -13 The initializer for a structure or union object that has automatic storage duration shall be - either an initializer list as described below, or a single expression that has compatible - structure or union type. In the latter case, the initial value of the object, including - unnamed members, is that of the expression. -14 An array of character type may be initialized by a character string literal or UTF-8 string - literal, optionally enclosed in braces. Successive bytes of the string literal (including the - terminating null character if there is room or if the array is of unknown size) initialize the - elements of the array. -15 An array with element type compatible with a qualified or unqualified version of - wchar_t may be initialized by a wide string literal, optionally enclosed in braces. - Successive wide characters of the wide string literal (including the terminating null wide - character if there is room or if the array is of unknown size) initialize the elements of the - array. -16 Otherwise, the initializer for an object that has aggregate or union type shall be a brace- - enclosed list of initializers for the elements or named members. - - -[page 138] - -17 Each brace-enclosed initializer list has an associated current object. When no - designations are present, subobjects of the current object are initialized in order according - to the type of the current object: array elements in increasing subscript order, structure - members in declaration order, and the first named member of a union.147) In contrast, a - designation causes the following initializer to begin initialization of the subobject - described by the designator. Initialization then continues forward in order, beginning - with the next subobject after that described by the designator.148) -18 Each designator list begins its description with the current object associated with the - closest surrounding brace pair. Each item in the designator list (in order) specifies a - particular member of its current object and changes the current object for the next - designator (if any) to be that member.149) The current object that results at the end of the - designator list is the subobject to be initialized by the following initializer. -19 The initialization shall occur in initializer list order, each initializer provided for a - particular subobject overriding any previously listed initializer for the same subobject;150) - all subobjects that are not initialized explicitly shall be initialized implicitly the same as - objects that have static storage duration. -20 If the aggregate or union contains elements or members that are aggregates or unions, - these rules apply recursively to the subaggregates or contained unions. If the initializer of - a subaggregate or contained union begins with a left brace, the initializers enclosed by - that brace and its matching right brace initialize the elements or members of the - subaggregate or the contained union. Otherwise, only enough initializers from the list are - taken to account for the elements or members of the subaggregate or the first member of - the contained union; any remaining initializers are left to initialize the next element or - member of the aggregate of which the current subaggregate or contained union is a part. -21 If there are fewer initializers in a brace-enclosed list than there are elements or members - of an aggregate, or fewer characters in a string literal used to initialize an array of known - size than there are elements in the array, the remainder of the aggregate shall be - initialized implicitly the same as objects that have static storage duration. - - - - 147) If the initializer list for a subaggregate or contained union does not begin with a left brace, its - subobjects are initialized as usual, but the subaggregate or contained union does not become the - current object: current objects are associated only with brace-enclosed initializer lists. - 148) After a union member is initialized, the next object is not the next member of the union; instead, it is - the next subobject of an object containing the union. - 149) Thus, a designator can only specify a strict subobject of the aggregate or union that is associated with - the surrounding brace pair. Note, too, that each separate designator list is independent. - 150) Any initializer for the subobject which is overridden and so not used to initialize that subobject might - not be evaluated at all. - -[page 139] - -22 If an array of unknown size is initialized, its size is determined by the largest indexed - element with an explicit initializer. The array type is completed at the end of its - initializer list. -23 The order in which any side effects occur among the initialization list expressions is - unspecified.151) -24 EXAMPLE 1 Provided that has been #included, the declarations - int i = 3.5; - double complex c = 5 + 3 * I; - define and initialize i with the value 3 and c with the value 5.0 + i3.0. - -25 EXAMPLE 2 The declaration - int x[] = { 1, 3, 5 }; - defines and initializes x as a one-dimensional array object that has three elements, as no size was specified - and there are three initializers. - -26 EXAMPLE 3 The declaration - int y[4][3] = { - { 1, 3, 5 }, - { 2, 4, 6 }, - { 3, 5, 7 }, - }; - is a definition with a fully bracketed initialization: 1, 3, and 5 initialize the first row of y (the array object - y[0]), namely y[0][0], y[0][1], and y[0][2]. Likewise the next two lines initialize y[1] and - y[2]. The initializer ends early, so y[3] is initialized with zeros. Precisely the same effect could have - been achieved by - int y[4][3] = { - 1, 3, 5, 2, 4, 6, 3, 5, 7 - }; - The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the - next three are taken successively for y[1] and y[2]. - -27 EXAMPLE 4 The declaration - int z[4][3] = { - { 1 }, { 2 }, { 3 }, { 4 } - }; - initializes the first column of z as specified and initializes the rest with zeros. - -28 EXAMPLE 5 The declaration - struct { int a[3], b; } w[] = { { 1 }, 2 }; - is a definition with an inconsistently bracketed initialization. It defines an array with two element - structures: w[0].a[0] is 1 and w[1].a[0] is 2; all the other elements are zero. - - - - 151) In particular, the evaluation order need not be the same as the order of subobject initialization. - -[page 140] - -29 EXAMPLE 6 The declaration - short q[4][3][2] = { - { 1 }, - { 2, 3 }, - { 4, 5, 6 } - }; - contains an incompletely but consistently bracketed initialization. It defines a three-dimensional array - object: q[0][0][0] is 1, q[1][0][0] is 2, q[1][0][1] is 3, and 4, 5, and 6 initialize - q[2][0][0], q[2][0][1], and q[2][1][0], respectively; all the rest are zero. The initializer for - q[0][0] does not begin with a left brace, so up to six items from the current list may be used. There is - only one, so the values for the remaining five elements are initialized with zero. Likewise, the initializers - for q[1][0] and q[2][0] do not begin with a left brace, so each uses up to six items, initializing their - respective two-dimensional subaggregates. If there had been more than six items in any of the lists, a - diagnostic message would have been issued. The same initialization result could have been achieved by: - short q[4][3][2] = { - 1, 0, 0, 0, 0, 0, - 2, 3, 0, 0, 0, 0, - 4, 5, 6 - }; - or by: - short q[4][3][2] = { - { - { 1 }, - }, - { - { 2, 3 }, - }, - { - { 4, 5 }, - { 6 }, - } - }; - in a fully bracketed form. -30 Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to - cause confusion. - -31 EXAMPLE 7 One form of initialization that completes array types involves typedef names. Given the - declaration - typedef int A[]; // OK - declared with block scope - the declaration - A a = { 1, 2 }, b = { 3, 4, 5 }; - is identical to - int a[] = { 1, 2 }, b[] = { 3, 4, 5 }; - due to the rules for incomplete types. - - - -[page 141] - -32 EXAMPLE 8 The declaration - char s[] = "abc", t[3] = "abc"; - defines ''plain'' char array objects s and t whose elements are initialized with character string literals. - This declaration is identical to - char s[] = { 'a', 'b', 'c', '\0' }, - t[] = { 'a', 'b', 'c' }; - The contents of the arrays are modifiable. On the other hand, the declaration - char *p = "abc"; - defines p with type ''pointer to char'' and initializes it to point to an object with type ''array of char'' - with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to - modify the contents of the array, the behavior is undefined. - -33 EXAMPLE 9 Arrays can be initialized to correspond to the elements of an enumeration by using - designators: - enum { member_one, member_two }; - const char *nm[] = { - [member_two] = "member two", - [member_one] = "member one", - }; - -34 EXAMPLE 10 Structure members can be initialized to nonzero values without depending on their order: - div_t answer = { .quot = 2, .rem = -1 }; - -35 EXAMPLE 11 Designators can be used to provide explicit initialization when unadorned initializer lists - might be misunderstood: - struct { int a[3], b; } w[] = - { [0].a = {1}, [1].a[0] = 2 }; - -36 EXAMPLE 12 Space can be ''allocated'' from both ends of an array by using a single designator: - int a[MAX] = { - 1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0 - }; -37 In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less - than ten, some of the values provided by the first five initializers will be overridden by the second five. - -38 EXAMPLE 13 Any member of a union can be initialized: - union { /* ... */ } u = { .any_member = 42 }; - - Forward references: common definitions (7.19). - - - - -[page 142] - - 6.7.10 Static assertions - Syntax -1 static_assert-declaration: - _Static_assert ( constant-expression , string-literal ) ; - Constraints -2 The constant expression shall compare unequal to 0. - Semantics -3 The constant expression shall be an integer constant expression. If the value of the - constant expression compares unequal to 0, the declaration has no effect. Otherwise, the - constraint is violated and the implementation shall produce a diagnostic message that - includes the text of the string literal, except that characters not in the basic source - character set are not required to appear in the message. - Forward references: diagnostics (7.2). - - - - -[page 143] - - 6.8 Statements and blocks - Syntax -1 statement: - labeled-statement - compound-statement - expression-statement - selection-statement - iteration-statement - jump-statement - Semantics -2 A statement specifies an action to be performed. Except as indicated, statements are - executed in sequence. -3 A block allows a set of declarations and statements to be grouped into one syntactic unit. - The initializers of objects that have automatic storage duration, and the variable length - array declarators of ordinary identifiers with block scope, are evaluated and the values are - stored in the objects (including storing an indeterminate value in objects without an - initializer) each time the declaration is reached in the order of execution, as if it were a - statement, and within each declaration in the order that declarators appear. -4 A full expression is an expression that is not part of another expression or of a declarator. - Each of the following is a full expression: an initializer that is not part of a compound - literal; the expression in an expression statement; the controlling expression of a selection - statement (if or switch); the controlling expression of a while or do statement; each - of the (optional) expressions of a for statement; the (optional) expression in a return - statement. There is a sequence point between the evaluation of a full expression and the - evaluation of the next full expression to be evaluated. - Forward references: expression and null statements (6.8.3), selection statements - (6.8.4), iteration statements (6.8.5), the return statement (6.8.6.4). - 6.8.1 Labeled statements - Syntax -1 labeled-statement: - identifier : statement - case constant-expression : statement - default : statement - Constraints -2 A case or default label shall appear only in a switch statement. Further - constraints on such labels are discussed under the switch statement. - -[page 144] - -3 Label names shall be unique within a function. - Semantics -4 Any statement may be preceded by a prefix that declares an identifier as a label name. - Labels in themselves do not alter the flow of control, which continues unimpeded across - them. - Forward references: the goto statement (6.8.6.1), the switch statement (6.8.4.2). - 6.8.2 Compound statement - Syntax -1 compound-statement: - { block-item-listopt } - block-item-list: - block-item - block-item-list block-item - block-item: - declaration - statement - Semantics -2 A compound statement is a block. - 6.8.3 Expression and null statements - Syntax -1 expression-statement: - expressionopt ; - Semantics -2 The expression in an expression statement is evaluated as a void expression for its side - effects.152) -3 A null statement (consisting of just a semicolon) performs no operations. -4 EXAMPLE 1 If a function call is evaluated as an expression statement for its side effects only, the - discarding of its value may be made explicit by converting the expression to a void expression by means of - a cast: - int p(int); - /* ... */ - (void)p(0); - - - - 152) Such as assignments, and function calls which have side effects. - -[page 145] - -5 EXAMPLE 2 In the program fragment - char *s; - /* ... */ - while (*s++ != '\0') - ; - a null statement is used to supply an empty loop body to the iteration statement. - -6 EXAMPLE 3 A null statement may also be used to carry a label just before the closing } of a compound - statement. - while (loop1) { - /* ... */ - while (loop2) { - /* ... */ - if (want_out) - goto end_loop1; - /* ... */ - } - /* ... */ - end_loop1: ; - } - - Forward references: iteration statements (6.8.5). - 6.8.4 Selection statements - Syntax -1 selection-statement: - if ( expression ) statement - if ( expression ) statement else statement - switch ( expression ) statement - Semantics -2 A selection statement selects among a set of statements depending on the value of a - controlling expression. -3 A selection statement is a block whose scope is a strict subset of the scope of its - enclosing block. Each associated substatement is also a block whose scope is a strict - subset of the scope of the selection statement. - 6.8.4.1 The if statement - Constraints -1 The controlling expression of an if statement shall have scalar type. - Semantics -2 In both forms, the first substatement is executed if the expression compares unequal to 0. - In the else form, the second substatement is executed if the expression compares equal - - -[page 146] - - to 0. If the first substatement is reached via a label, the second substatement is not - executed. -3 An else is associated with the lexically nearest preceding if that is allowed by the - syntax. - 6.8.4.2 The switch statement - Constraints -1 The controlling expression of a switch statement shall have integer type. -2 If a switch statement has an associated case or default label within the scope of an - identifier with a variably modified type, the entire switch statement shall be within the - scope of that identifier.153) -3 The expression of each case label shall be an integer constant expression and no two of - the case constant expressions in the same switch statement shall have the same value - after conversion. There may be at most one default label in a switch statement. - (Any enclosed switch statement may have a default label or case constant - expressions with values that duplicate case constant expressions in the enclosing - switch statement.) - Semantics -4 A switch statement causes control to jump to, into, or past the statement that is the - switch body, depending on the value of a controlling expression, and on the presence of a - default label and the values of any case labels on or in the switch body. A case or - default label is accessible only within the closest enclosing switch statement. -5 The integer promotions are performed on the controlling expression. The constant - expression in each case label is converted to the promoted type of the controlling - expression. If a converted value matches that of the promoted controlling expression, - control jumps to the statement following the matched case label. Otherwise, if there is - a default label, control jumps to the labeled statement. If no converted case constant - expression matches and there is no default label, no part of the switch body is - executed. - Implementation limits -6 As discussed in 5.2.4.1, the implementation may limit the number of case values in a - switch statement. - - - - - 153) That is, the declaration either precedes the switch statement, or it follows the last case or - default label associated with the switch that is in the block containing the declaration. - -[page 147] - -7 EXAMPLE In the artificial program fragment - switch (expr) - { - int i = 4; - f(i); - case 0: - i = 17; - /* falls through into default code */ - default: - printf("%d\n", i); - } - the object whose identifier is i exists with automatic storage duration (within the block) but is never - initialized, and thus if the controlling expression has a nonzero value, the call to the printf function will - access an indeterminate value. Similarly, the call to the function f cannot be reached. - - 6.8.5 Iteration statements - Syntax -1 iteration-statement: - while ( expression ) statement - do statement while ( expression ) ; - for ( expressionopt ; expressionopt ; expressionopt ) statement - for ( declaration expressionopt ; expressionopt ) statement - Constraints -2 The controlling expression of an iteration statement shall have scalar type. -3 The declaration part of a for statement shall only declare identifiers for objects having - storage class auto or register. - Semantics -4 An iteration statement causes a statement called the loop body to be executed repeatedly - until the controlling expression compares equal to 0. The repetition occurs regardless of - whether the loop body is entered from the iteration statement or by a jump.154) -5 An iteration statement is a block whose scope is a strict subset of the scope of its - enclosing block. The loop body is also a block whose scope is a strict subset of the scope - of the iteration statement. -6 An iteration statement that performs no input/output operations, does not access volatile - objects, and performs no synchronization or atomic operations in its body, controlling - expression, or (in the case of a for statement) its expression-3, may be assumed by the - implementation to terminate.155) - - 154) Code jumped over is not executed. In particular, the controlling expression of a for or while - statement is not evaluated before entering the loop body, nor is clause-1 of a for statement. - -[page 148] - - 6.8.5.1 The while statement -1 The evaluation of the controlling expression takes place before each execution of the loop - body. - 6.8.5.2 The do statement -1 The evaluation of the controlling expression takes place after each execution of the loop - body. - 6.8.5.3 The for statement -1 The statement - for ( clause-1 ; expression-2 ; expression-3 ) statement - behaves as follows: The expression expression-2 is the controlling expression that is - evaluated before each execution of the loop body. The expression expression-3 is - evaluated as a void expression after each execution of the loop body. If clause-1 is a - declaration, the scope of any identifiers it declares is the remainder of the declaration and - the entire loop, including the other two expressions; it is reached in the order of execution - before the first evaluation of the controlling expression. If clause-1 is an expression, it is - evaluated as a void expression before the first evaluation of the controlling expression.156) -2 Both clause-1 and expression-3 can be omitted. An omitted expression-2 is replaced by a - nonzero constant. - 6.8.6 Jump statements - Syntax -1 jump-statement: - goto identifier ; - continue ; - break ; - return expressionopt ; - Semantics -2 A jump statement causes an unconditional jump to another place. - - - - - 155) This is intended to allow compiler transformations such as removal of empty loops even when - termination cannot be proven. - 156) Thus, clause-1 specifies initialization for the loop, possibly declaring one or more variables for use in - the loop; the controlling expression, expression-2, specifies an evaluation made before each iteration, - such that execution of the loop continues until the expression compares equal to 0; and expression-3 - specifies an operation (such as incrementing) that is performed after each iteration. - -[page 149] - - 6.8.6.1 The goto statement - Constraints -1 The identifier in a goto statement shall name a label located somewhere in the enclosing - function. A goto statement shall not jump from outside the scope of an identifier having - a variably modified type to inside the scope of that identifier. - Semantics -2 A goto statement causes an unconditional jump to the statement prefixed by the named - label in the enclosing function. -3 EXAMPLE 1 It is sometimes convenient to jump into the middle of a complicated set of statements. The - following outline presents one possible approach to a problem based on these three assumptions: - 1. The general initialization code accesses objects only visible to the current function. - 2. The general initialization code is too large to warrant duplication. - 3. The code to determine the next operation is at the head of the loop. (To allow it to be reached by - continue statements, for example.) - /* ... */ - goto first_time; - for (;;) { - // determine next operation - /* ... */ - if (need to reinitialize) { - // reinitialize-only code - /* ... */ - first_time: - // general initialization code - /* ... */ - continue; - } - // handle other operations - /* ... */ - } - - - - -[page 150] - -4 EXAMPLE 2 A goto statement is not allowed to jump past any declarations of objects with variably - modified types. A jump within the scope, however, is permitted. - goto lab3; // invalid: going INTO scope of VLA. - { - double a[n]; - a[j] = 4.4; - lab3: - a[j] = 3.3; - goto lab4; // valid: going WITHIN scope of VLA. - a[j] = 5.5; - lab4: - a[j] = 6.6; - } - goto lab4; // invalid: going INTO scope of VLA. - - 6.8.6.2 The continue statement - Constraints -1 A continue statement shall appear only in or as a loop body. - Semantics -2 A continue statement causes a jump to the loop-continuation portion of the smallest - enclosing iteration statement; that is, to the end of the loop body. More precisely, in each - of the statements - while (/* ... */) { do { for (/* ... */) { - /* ... */ /* ... */ /* ... */ - continue; continue; continue; - /* ... */ /* ... */ /* ... */ - contin: ; contin: ; contin: ; - } } while (/* ... */); } - unless the continue statement shown is in an enclosed iteration statement (in which - case it is interpreted within that statement), it is equivalent to goto contin;.157) - 6.8.6.3 The break statement - Constraints -1 A break statement shall appear only in or as a switch body or loop body. - Semantics -2 A break statement terminates execution of the smallest enclosing switch or iteration - statement. - - - - 157) Following the contin: label is a null statement. - -[page 151] - - 6.8.6.4 The return statement - Constraints -1 A return statement with an expression shall not appear in a function whose return type - is void. A return statement without an expression shall only appear in a function - whose return type is void. - Semantics -2 A return statement terminates execution of the current function and returns control to - its caller. A function may have any number of return statements. -3 If a return statement with an expression is executed, the value of the expression is - returned to the caller as the value of the function call expression. If the expression has a - type different from the return type of the function in which it appears, the value is - converted as if by assignment to an object having the return type of the function.158) -4 EXAMPLE In: - struct s { double i; } f(void); - union { - struct { - int f1; - struct s f2; - } u1; - struct { - struct s f3; - int f4; - } u2; - } g; - struct s f(void) - { - return g.u1.f2; - } - /* ... */ - g.u2.f3 = f(); - there is no undefined behavior, although there would be if the assignment were done directly (without using - a function call to fetch the value). - - - - - 158) The return statement is not an assignment. The overlap restriction of subclause 6.5.16.1 does not - apply to the case of function return. The representation of floating-point values may have wider range - or precision than implied by the type; a cast may be used to remove this extra range and precision. - -[page 152] - - 6.9 External definitions - Syntax -1 translation-unit: - external-declaration - translation-unit external-declaration - external-declaration: - function-definition - declaration - Constraints -2 The storage-class specifiers auto and register shall not appear in the declaration - specifiers in an external declaration. -3 There shall be no more than one external definition for each identifier declared with - internal linkage in a translation unit. Moreover, if an identifier declared with internal - linkage is used in an expression (other than as a part of the operand of a sizeof - operator whose result is an integer constant), there shall be exactly one external definition - for the identifier in the translation unit. - Semantics -4 As discussed in 5.1.1.1, the unit of program text after preprocessing is a translation unit, - which consists of a sequence of external declarations. These are described as ''external'' - because they appear outside any function (and hence have file scope). As discussed in - 6.7, a declaration that also causes storage to be reserved for an object or a function named - by the identifier is a definition. -5 An external definition is an external declaration that is also a definition of a function - (other than an inline definition) or an object. If an identifier declared with external - linkage is used in an expression (other than as part of the operand of a sizeof operator - whose result is an integer constant), somewhere in the entire program there shall be - exactly one external definition for the identifier; otherwise, there shall be no more than - one.159) - - - - - 159) Thus, if an identifier declared with external linkage is not used in an expression, there need be no - external definition for it. - -[page 153] - - 6.9.1 Function definitions - Syntax -1 function-definition: - declaration-specifiers declarator declaration-listopt compound-statement - declaration-list: - declaration - declaration-list declaration - Constraints -2 The identifier declared in a function definition (which is the name of the function) shall - have a function type, as specified by the declarator portion of the function definition.160) -3 The return type of a function shall be void or a complete object type other than array - type. -4 The storage-class specifier, if any, in the declaration specifiers shall be either extern or - static. -5 If the declarator includes a parameter type list, the declaration of each parameter shall - include an identifier, except for the special case of a parameter list consisting of a single - parameter of type void, in which case there shall not be an identifier. No declaration list - shall follow. -6 If the declarator includes an identifier list, each declaration in the declaration list shall - have at least one declarator, those declarators shall declare only identifiers from the - identifier list, and every identifier in the identifier list shall be declared. An identifier - declared as a typedef name shall not be redeclared as a parameter. The declarations in the - declaration list shall contain no storage-class specifier other than register and no - initializations. - - - - 160) The intent is that the type category in a function definition cannot be inherited from a typedef: - typedef int F(void); // type F is ''function with no parameters - // returning int'' - F f, g; // f and g both have type compatible with F - F f { /* ... */ } // WRONG: syntax/constraint error - F g() { /* ... */ } // WRONG: declares that g returns a function - int f(void) { /* ... */ } // RIGHT: f has type compatible with F - int g() { /* ... */ } // RIGHT: g has type compatible with F - F *e(void) { /* ... */ } // e returns a pointer to a function - F *((e))(void) { /* ... */ } // same: parentheses irrelevant - int (*fp)(void); // fp points to a function that has type F - F *Fp; // Fp points to a function that has type F - - -[page 154] - - Semantics -7 The declarator in a function definition specifies the name of the function being defined - and the identifiers of its parameters. If the declarator includes a parameter type list, the - list also specifies the types of all the parameters; such a declarator also serves as a - function prototype for later calls to the same function in the same translation unit. If the - declarator includes an identifier list,161) the types of the parameters shall be declared in a - following declaration list. In either case, the type of each parameter is adjusted as - described in 6.7.6.3 for a parameter type list; the resulting type shall be a complete object - type. -8 If a function that accepts a variable number of arguments is defined without a parameter - type list that ends with the ellipsis notation, the behavior is undefined. -9 Each parameter has automatic storage duration; its identifier is an lvalue.162) The layout - of the storage for parameters is unspecified. -10 On entry to the function, the size expressions of each variably modified parameter are - evaluated and the value of each argument expression is converted to the type of the - corresponding parameter as if by assignment. (Array expressions and function - designators as arguments were converted to pointers before the call.) -11 After all parameters have been assigned, the compound statement that constitutes the - body of the function definition is executed. -12 If the } that terminates a function is reached, and the value of the function call is used by - the caller, the behavior is undefined. -13 EXAMPLE 1 In the following: - extern int max(int a, int b) - { - return a > b ? a : b; - } - extern is the storage-class specifier and int is the type specifier; max(int a, int b) is the - function declarator; and - { return a > b ? a : b; } - is the function body. The following similar definition uses the identifier-list form for the parameter - declarations: - - - - - 161) See ''future language directions'' (6.11.7). - 162) A parameter identifier cannot be redeclared in the function body except in an enclosed block. - -[page 155] - - extern int max(a, b) - int a, b; - { - return a > b ? a : b; - } - Here int a, b; is the declaration list for the parameters. The difference between these two definitions is - that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls - to the function, whereas the second form does not. - -14 EXAMPLE 2 To pass one function to another, one might say - int f(void); - /* ... */ - g(f); - Then the definition of g might read - void g(int (*funcp)(void)) - { - /* ... */ - (*funcp)(); /* or funcp(); ... */ - } - or, equivalently, - void g(int func(void)) - { - /* ... */ - func(); /* or (*func)(); ... */ - } - - 6.9.2 External object definitions - Semantics -1 If the declaration of an identifier for an object has file scope and an initializer, the - declaration is an external definition for the identifier. -2 A declaration of an identifier for an object that has file scope without an initializer, and - without a storage-class specifier or with the storage-class specifier static, constitutes a - tentative definition. If a translation unit contains one or more tentative definitions for an - identifier, and the translation unit contains no external definition for that identifier, then - the behavior is exactly as if the translation unit contains a file scope declaration of that - identifier, with the composite type as of the end of the translation unit, with an initializer - equal to 0. -3 If the declaration of an identifier for an object is a tentative definition and has internal - linkage, the declared type shall not be an incomplete type. - - - - -[page 156] - -4 EXAMPLE 1 - int i1 = 1; // definition, external linkage - static int i2 = 2; // definition, internal linkage - extern int i3 = 3; // definition, external linkage - int i4; // tentative definition, external linkage - static int i5; // tentative definition, internal linkage - int i1; // valid tentative definition, refers to previous - int i2; // 6.2.2 renders undefined, linkage disagreement - int i3; // valid tentative definition, refers to previous - int i4; // valid tentative definition, refers to previous - int i5; // 6.2.2 renders undefined, linkage disagreement - extern int i1; // refers to previous, whose linkage is external - extern int i2; // refers to previous, whose linkage is internal - extern int i3; // refers to previous, whose linkage is external - extern int i4; // refers to previous, whose linkage is external - extern int i5; // refers to previous, whose linkage is internal - -5 EXAMPLE 2 If at the end of the translation unit containing - int i[]; - the array i still has incomplete type, the implicit initializer causes it to have one element, which is set to - zero on program startup. - - - - -[page 157] - - 6.10 Preprocessing directives - Syntax -1 preprocessing-file: - groupopt - group: - group-part - group group-part - group-part: - if-section - control-line - text-line - # non-directive - if-section: - if-group elif-groupsopt else-groupopt endif-line - if-group: - # if constant-expression new-line groupopt - # ifdef identifier new-line groupopt - # ifndef identifier new-line groupopt - elif-groups: - elif-group - elif-groups elif-group - elif-group: - # elif constant-expression new-line groupopt - else-group: - # else new-line groupopt - endif-line: - # endif new-line - - - - -[page 158] - - control-line: - # include pp-tokens new-line - # define identifier replacement-list new-line - # define identifier lparen identifier-listopt ) - replacement-list new-line - # define identifier lparen ... ) replacement-list new-line - # define identifier lparen identifier-list , ... ) - replacement-list new-line - # undef identifier new-line - # line pp-tokens new-line - # error pp-tokensopt new-line - # pragma pp-tokensopt new-line - # new-line - text-line: - pp-tokensopt new-line - non-directive: - pp-tokens new-line - lparen: - a ( character not immediately preceded by white-space - replacement-list: - pp-tokensopt - pp-tokens: - preprocessing-token - pp-tokens preprocessing-token - new-line: - the new-line character - Description -2 A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the - following constraints: The first token in the sequence is a # preprocessing token that (at - the start of translation phase 4) is either the first character in the source file (optionally - after white space containing no new-line characters) or that follows white space - containing at least one new-line character. The last token in the sequence is the first new- - line character that follows the first token in the sequence.163) A new-line character ends - the preprocessing directive even if it occurs within what would otherwise be an - - 163) Thus, preprocessing directives are commonly called ''lines''. These ''lines'' have no other syntactic - significance, as all white space is equivalent except in certain situations during preprocessing (see the - # character string literal creation operator in 6.10.3.2, for example). - -[page 159] - - invocation of a function-like macro. -3 A text line shall not begin with a # preprocessing token. A non-directive shall not begin - with any of the directive names appearing in the syntax. -4 When in a group that is skipped (6.10.1), the directive syntax is relaxed to allow any - sequence of preprocessing tokens to occur between the directive name and the following - new-line character. - Constraints -5 The only white-space characters that shall appear between preprocessing tokens within a - preprocessing directive (from just after the introducing # preprocessing token through - just before the terminating new-line character) are space and horizontal-tab (including - spaces that have replaced comments or possibly other white-space characters in - translation phase 3). - Semantics -6 The implementation can process and skip sections of source files conditionally, include - other source files, and replace macros. These capabilities are called preprocessing, - because conceptually they occur before translation of the resulting translation unit. -7 The preprocessing tokens within a preprocessing directive are not subject to macro - expansion unless otherwise stated. -8 EXAMPLE In: - #define EMPTY - EMPTY # include - the sequence of preprocessing tokens on the second line is not a preprocessing directive, because it does not - begin with a # at the start of translation phase 4, even though it will do so after the macro EMPTY has been - replaced. - - 6.10.1 Conditional inclusion - Constraints -1 The expression that controls conditional inclusion shall be an integer constant expression - except that: identifiers (including those lexically identical to keywords) are interpreted as - described below;164) and it may contain unary operator expressions of the form - defined identifier - or - defined ( identifier ) - which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is - - - 164) Because the controlling constant expression is evaluated during translation phase 4, all identifiers - either are or are not macro names -- there simply are no keywords, enumeration constants, etc. - -[page 160] - - predefined or if it has been the subject of a #define preprocessing directive without an - intervening #undef directive with the same subject identifier), 0 if it is not. -2 Each preprocessing token that remains (in the list of preprocessing tokens that will - become the controlling expression) after all macro replacements have occurred shall be in - the lexical form of a token (6.4). - Semantics -3 Preprocessing directives of the forms - # if constant-expression new-line groupopt - # elif constant-expression new-line groupopt - check whether the controlling constant expression evaluates to nonzero. -4 Prior to evaluation, macro invocations in the list of preprocessing tokens that will become - the controlling constant expression are replaced (except for those macro names modified - by the defined unary operator), just as in normal text. If the token defined is - generated as a result of this replacement process or use of the defined unary operator - does not match one of the two specified forms prior to macro replacement, the behavior is - undefined. After all replacements due to macro expansion and the defined unary - operator have been performed, all remaining identifiers (including those lexically - identical to keywords) are replaced with the pp-number 0, and then each preprocessing - token is converted into a token. The resulting tokens compose the controlling constant - expression which is evaluated according to the rules of 6.6. For the purposes of this - token conversion and evaluation, all signed integer types and all unsigned integer types - act as if they have the same representation as, respectively, the types intmax_t and - uintmax_t defined in the header .165) This includes interpreting - character constants, which may involve converting escape sequences into execution - character set members. Whether the numeric value for these character constants matches - the value obtained when an identical character constant occurs in an expression (other - than within a #if or #elif directive) is implementation-defined.166) Also, whether a - single-character character constant may have a negative value is implementation-defined. - - - - - 165) Thus, on an implementation where INT_MAX is 0x7FFF and UINT_MAX is 0xFFFF, the constant - 0x8000 is signed and positive within a #if expression even though it would be unsigned in - translation phase 7. - 166) Thus, the constant expression in the following #if directive and if statement is not guaranteed to - evaluate to the same value in these two contexts. - #if 'z' - 'a' == 25 - if ('z' - 'a' == 25) - - -[page 161] - -5 Preprocessing directives of the forms - # ifdef identifier new-line groupopt - # ifndef identifier new-line groupopt - check whether the identifier is or is not currently defined as a macro name. Their - conditions are equivalent to #if defined identifier and #if !defined identifier - respectively. -6 Each directive's condition is checked in order. If it evaluates to false (zero), the group - that it controls is skipped: directives are processed only through the name that determines - the directive in order to keep track of the level of nested conditionals; the rest of the - directives' preprocessing tokens are ignored, as are the other preprocessing tokens in the - group. Only the first group whose control condition evaluates to true (nonzero) is - processed. If none of the conditions evaluates to true, and there is a #else directive, the - group controlled by the #else is processed; lacking a #else directive, all the groups - until the #endif are skipped.167) - Forward references: macro replacement (6.10.3), source file inclusion (6.10.2), largest - integer types (7.20.1.5). - 6.10.2 Source file inclusion - Constraints -1 A #include directive shall identify a header or source file that can be processed by the - implementation. - Semantics -2 A preprocessing directive of the form - # include new-line - searches a sequence of implementation-defined places for a header identified uniquely by - the specified sequence between the < and > delimiters, and causes the replacement of that - directive by the entire contents of the header. How the places are specified or the header - identified is implementation-defined. -3 A preprocessing directive of the form - # include "q-char-sequence" new-line - causes the replacement of that directive by the entire contents of the source file identified - by the specified sequence between the " delimiters. The named source file is searched - - - 167) As indicated by the syntax, a preprocessing token shall not follow a #else or #endif directive - before the terminating new-line character. However, comments may appear anywhere in a source file, - including within a preprocessing directive. - -[page 162] - - for in an implementation-defined manner. If this search is not supported, or if the search - fails, the directive is reprocessed as if it read - # include new-line - with the identical contained sequence (including > characters, if any) from the original - directive. -4 A preprocessing directive of the form - # include pp-tokens new-line - (that does not match one of the two previous forms) is permitted. The preprocessing - tokens after include in the directive are processed just as in normal text. (Each - identifier currently defined as a macro name is replaced by its replacement list of - preprocessing tokens.) The directive resulting after all replacements shall match one of - the two previous forms.168) The method by which a sequence of preprocessing tokens - between a < and a > preprocessing token pair or a pair of " characters is combined into a - single header name preprocessing token is implementation-defined. -5 The implementation shall provide unique mappings for sequences consisting of one or - more nondigits or digits (6.4.2.1) followed by a period (.) and a single nondigit. The - first character shall not be a digit. The implementation may ignore distinctions of - alphabetical case and restrict the mapping to eight significant characters before the - period. -6 A #include preprocessing directive may appear in a source file that has been read - because of a #include directive in another file, up to an implementation-defined - nesting limit (see 5.2.4.1). -7 EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following: - #include - #include "myprog.h" - - - - - 168) Note that adjacent string literals are not concatenated into a single string literal (see the translation - phases in 5.1.1.2); thus, an expansion that results in two string literals is an invalid directive. - -[page 163] - -8 EXAMPLE 2 This illustrates macro-replaced #include directives: - #if VERSION == 1 - #define INCFILE "vers1.h" - #elif VERSION == 2 - #define INCFILE "vers2.h" // and so on - #else - #define INCFILE "versN.h" - #endif - #include INCFILE - - Forward references: macro replacement (6.10.3). - 6.10.3 Macro replacement - Constraints -1 Two replacement lists are identical if and only if the preprocessing tokens in both have - the same number, ordering, spelling, and white-space separation, where all white-space - separations are considered identical. -2 An identifier currently defined as an object-like macro shall not be redefined by another - #define preprocessing directive unless the second definition is an object-like macro - definition and the two replacement lists are identical. Likewise, an identifier currently - defined as a function-like macro shall not be redefined by another #define - preprocessing directive unless the second definition is a function-like macro definition - that has the same number and spelling of parameters, and the two replacement lists are - identical. -3 There shall be white-space between the identifier and the replacement list in the definition - of an object-like macro. -4 If the identifier-list in the macro definition does not end with an ellipsis, the number of - arguments (including those arguments consisting of no preprocessing tokens) in an - invocation of a function-like macro shall equal the number of parameters in the macro - definition. Otherwise, there shall be more arguments in the invocation than there are - parameters in the macro definition (excluding the ...). There shall exist a ) - preprocessing token that terminates the invocation. -5 The identifier __VA_ARGS__ shall occur only in the replacement-list of a function-like - macro that uses the ellipsis notation in the parameters. -6 A parameter identifier in a function-like macro shall be uniquely declared within its - scope. - Semantics -7 The identifier immediately following the define is called the macro name. There is one - name space for macro names. Any white-space characters preceding or following the - replacement list of preprocessing tokens are not considered part of the replacement list - -[page 164] - - for either form of macro. -8 If a # preprocessing token, followed by an identifier, occurs lexically at the point at which - a preprocessing directive could begin, the identifier is not subject to macro replacement. -9 A preprocessing directive of the form - # define identifier replacement-list new-line - defines an object-like macro that causes each subsequent instance of the macro name169) - to be replaced by the replacement list of preprocessing tokens that constitute the - remainder of the directive. The replacement list is then rescanned for more macro names - as specified below. -10 A preprocessing directive of the form - # define identifier lparen identifier-listopt ) replacement-list new-line - # define identifier lparen ... ) replacement-list new-line - # define identifier lparen identifier-list , ... ) replacement-list new-line - defines a function-like macro with parameters, whose use is similar syntactically to a - function call. The parameters are specified by the optional list of identifiers, whose scope - extends from their declaration in the identifier list until the new-line character that - terminates the #define preprocessing directive. Each subsequent instance of the - function-like macro name followed by a ( as the next preprocessing token introduces the - sequence of preprocessing tokens that is replaced by the replacement list in the definition - (an invocation of the macro). The replaced sequence of preprocessing tokens is - terminated by the matching ) preprocessing token, skipping intervening matched pairs of - left and right parenthesis preprocessing tokens. Within the sequence of preprocessing - tokens making up an invocation of a function-like macro, new-line is considered a normal - white-space character. -11 The sequence of preprocessing tokens bounded by the outside-most matching parentheses - forms the list of arguments for the function-like macro. The individual arguments within - the list are separated by comma preprocessing tokens, but comma preprocessing tokens - between matching inner parentheses do not separate arguments. If there are sequences of - preprocessing tokens within the list of arguments that would otherwise act as - preprocessing directives,170) the behavior is undefined. -12 If there is a ... in the identifier-list in the macro definition, then the trailing arguments, - including any separating comma preprocessing tokens, are merged to form a single item: - - - 169) Since, by macro-replacement time, all character constants and string literals are preprocessing tokens, - not sequences possibly containing identifier-like subsequences (see 5.1.1.2, translation phases), they - are never scanned for macro names or parameters. - 170) Despite the name, a non-directive is a preprocessing directive. - -[page 165] - - the variable arguments. The number of arguments so combined is such that, following - merger, the number of arguments is one more than the number of parameters in the macro - definition (excluding the ...). - 6.10.3.1 Argument substitution -1 After the arguments for the invocation of a function-like macro have been identified, - argument substitution takes place. A parameter in the replacement list, unless preceded - by a # or ## preprocessing token or followed by a ## preprocessing token (see below), is - replaced by the corresponding argument after all macros contained therein have been - expanded. Before being substituted, each argument's preprocessing tokens are - completely macro replaced as if they formed the rest of the preprocessing file; no other - preprocessing tokens are available. -2 An identifier __VA_ARGS__ that occurs in the replacement list shall be treated as if it - were a parameter, and the variable arguments shall form the preprocessing tokens used to - replace it. - 6.10.3.2 The # operator - Constraints -1 Each # preprocessing token in the replacement list for a function-like macro shall be - followed by a parameter as the next preprocessing token in the replacement list. - Semantics -2 If, in the replacement list, a parameter is immediately preceded by a # preprocessing - token, both are replaced by a single character string literal preprocessing token that - contains the spelling of the preprocessing token sequence for the corresponding - argument. Each occurrence of white space between the argument's preprocessing tokens - becomes a single space character in the character string literal. White space before the - first preprocessing token and after the last preprocessing token composing the argument - is deleted. Otherwise, the original spelling of each preprocessing token in the argument - is retained in the character string literal, except for special handling for producing the - spelling of string literals and character constants: a \ character is inserted before each " - and \ character of a character constant or string literal (including the delimiting " - characters), except that it is implementation-defined whether a \ character is inserted - before the \ character beginning a universal character name. If the replacement that - results is not a valid character string literal, the behavior is undefined. The character - string literal corresponding to an empty argument is "". The order of evaluation of # and - ## operators is unspecified. - - - - -[page 166] - - 6.10.3.3 The ## operator - Constraints -1 A ## preprocessing token shall not occur at the beginning or at the end of a replacement - list for either form of macro definition. - Semantics -2 If, in the replacement list of a function-like macro, a parameter is immediately preceded - or followed by a ## preprocessing token, the parameter is replaced by the corresponding - argument's preprocessing token sequence; however, if an argument consists of no - preprocessing tokens, the parameter is replaced by a placemarker preprocessing token - instead.171) -3 For both object-like and function-like macro invocations, before the replacement list is - reexamined for more macro names to replace, each instance of a ## preprocessing token - in the replacement list (not from an argument) is deleted and the preceding preprocessing - token is concatenated with the following preprocessing token. Placemarker - preprocessing tokens are handled specially: concatenation of two placemarkers results in - a single placemarker preprocessing token, and concatenation of a placemarker with a - non-placemarker preprocessing token results in the non-placemarker preprocessing token. - If the result is not a valid preprocessing token, the behavior is undefined. The resulting - token is available for further macro replacement. The order of evaluation of ## operators - is unspecified. -4 EXAMPLE In the following fragment: - #define hash_hash # ## # - #define mkstr(a) # a - #define in_between(a) mkstr(a) - #define join(c, d) in_between(c hash_hash d) - char p[] = join(x, y); // equivalent to - // char p[] = "x ## y"; - The expansion produces, at various stages: - join(x, y) - in_between(x hash_hash y) - in_between(x ## y) - mkstr(x ## y) - "x ## y" - In other words, expanding hash_hash produces a new token, consisting of two adjacent sharp signs, but - this new token is not the ## operator. - - - 171) Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that - exist only within translation phase 4. - -[page 167] - - 6.10.3.4 Rescanning and further replacement -1 After all parameters in the replacement list have been substituted and # and ## - processing has taken place, all placemarker preprocessing tokens are removed. The - resulting preprocessing token sequence is then rescanned, along with all subsequent - preprocessing tokens of the source file, for more macro names to replace. -2 If the name of the macro being replaced is found during this scan of the replacement list - (not including the rest of the source file's preprocessing tokens), it is not replaced. - Furthermore, if any nested replacements encounter the name of the macro being replaced, - it is not replaced. These nonreplaced macro name preprocessing tokens are no longer - available for further replacement even if they are later (re)examined in contexts in which - that macro name preprocessing token would otherwise have been replaced. -3 The resulting completely macro-replaced preprocessing token sequence is not processed - as a preprocessing directive even if it resembles one, but all pragma unary operator - expressions within it are then processed as specified in 6.10.9 below. - 6.10.3.5 Scope of macro definitions -1 A macro definition lasts (independent of block structure) until a corresponding #undef - directive is encountered or (if none is encountered) until the end of the preprocessing - translation unit. Macro definitions have no significance after translation phase 4. -2 A preprocessing directive of the form - # undef identifier new-line - causes the specified identifier no longer to be defined as a macro name. It is ignored if - the specified identifier is not currently defined as a macro name. -3 EXAMPLE 1 The simplest use of this facility is to define a ''manifest constant'', as in - #define TABSIZE 100 - int table[TABSIZE]; - -4 EXAMPLE 2 The following defines a function-like macro whose value is the maximum of its arguments. - It has the advantages of working for any compatible types of the arguments and of generating in-line code - without the overhead of function calling. It has the disadvantages of evaluating one or the other of its - arguments a second time (including side effects) and generating more code than a function if invoked - several times. It also cannot have its address taken, as it has none. - #define max(a, b) ((a) > (b) ? (a) : (b)) - The parentheses ensure that the arguments and the resulting expression are bound properly. - - - - -[page 168] - -5 EXAMPLE 3 To illustrate the rules for redefinition and reexamination, the sequence - #define x 3 - #define f(a) f(x * (a)) - #undef x - #define x 2 - #define g f - #define z z[0] - #define h g(~ - #define m(a) a(w) - #define w 0,1 - #define t(a) a - #define p() int - #define q(x) x - #define r(x,y) x ## y - #define str(x) # x - f(y+1) + f(f(z)) % t(t(g)(0) + t)(1); - g(x+(3,4)-w) | h 5) & m - (f)^m(m); - p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) }; - char c[2][6] = { str(hello), str() }; - results in - f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1); - f(2 * (2+(3,4)-0,1)) | f(2 * (~ 5)) & f(2 * (0,1))^m(0,1); - int i[] = { 1, 23, 4, 5, }; - char c[2][6] = { "hello", "" }; - -6 EXAMPLE 4 To illustrate the rules for creating character string literals and concatenating tokens, the - sequence - #define str(s) # s - #define xstr(s) str(s) - #define debug(s, t) printf("x" # s "= %d, x" # t "= %s", \ - x ## s, x ## t) - #define INCFILE(n) vers ## n - #define glue(a, b) a ## b - #define xglue(a, b) glue(a, b) - #define HIGHLOW "hello" - #define LOW LOW ", world" - debug(1, 2); - fputs(str(strncmp("abc\0d", "abc", '\4') // this goes away - == 0) str(: @\n), s); - #include xstr(INCFILE(2).h) - glue(HIGH, LOW); - xglue(HIGH, LOW) - results in - - - - -[page 169] - - printf("x" "1" "= %d, x" "2" "= %s", x1, x2); - fputs( - "strncmp(\"abc\\0d\", \"abc\", '\\4') == 0" ": @\n", - s); - #include "vers2.h" (after macro replacement, before file access) - "hello"; - "hello" ", world" - or, after concatenation of the character string literals, - printf("x1= %d, x2= %s", x1, x2); - fputs( - "strncmp(\"abc\\0d\", \"abc\", '\\4') == 0: @\n", - s); - #include "vers2.h" (after macro replacement, before file access) - "hello"; - "hello, world" - Space around the # and ## tokens in the macro definition is optional. - -7 EXAMPLE 5 To illustrate the rules for placemarker preprocessing tokens, the sequence - #define t(x,y,z) x ## y ## z - int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,), - t(10,,), t(,11,), t(,,12), t(,,) }; - results in - int j[] = { 123, 45, 67, 89, - 10, 11, 12, }; - -8 EXAMPLE 6 To demonstrate the redefinition rules, the following sequence is valid. - #define OBJ_LIKE (1-1) - #define OBJ_LIKE /* white space */ (1-1) /* other */ - #define FUNC_LIKE(a) ( a ) - #define FUNC_LIKE( a )( /* note the white space */ \ - a /* other stuff on this line - */ ) - But the following redefinitions are invalid: - #define OBJ_LIKE (0) // different token sequence - #define OBJ_LIKE (1 - 1) // different white space - #define FUNC_LIKE(b) ( a ) // different parameter usage - #define FUNC_LIKE(b) ( b ) // different parameter spelling - -9 EXAMPLE 7 Finally, to show the variable argument list macro facilities: - #define debug(...) fprintf(stderr, __VA_ARGS__) - #define showlist(...) puts(#__VA_ARGS__) - #define report(test, ...) ((test)?puts(#test):\ - printf(__VA_ARGS__)) - debug("Flag"); - debug("X = %d\n", x); - showlist(The first, second, and third items.); - report(x>y, "x is %d but y is %d", x, y); - - -[page 170] - - results in - fprintf(stderr, "Flag" ); - fprintf(stderr, "X = %d\n", x ); - puts( "The first, second, and third items." ); - ((x>y)?puts("x>y"): - printf("x is %d but y is %d", x, y)); - - 6.10.4 Line control - Constraints -1 The string literal of a #line directive, if present, shall be a character string literal. - Semantics -2 The line number of the current source line is one greater than the number of new-line - characters read or introduced in translation phase 1 (5.1.1.2) while processing the source - file to the current token. -3 A preprocessing directive of the form - # line digit-sequence new-line - causes the implementation to behave as if the following sequence of source lines begins - with a source line that has a line number as specified by the digit sequence (interpreted as - a decimal integer). The digit sequence shall not specify zero, nor a number greater than - 2147483647. -4 A preprocessing directive of the form - # line digit-sequence "s-char-sequenceopt" new-line - sets the presumed line number similarly and changes the presumed name of the source - file to be the contents of the character string literal. -5 A preprocessing directive of the form - # line pp-tokens new-line - (that does not match one of the two previous forms) is permitted. The preprocessing - tokens after line on the directive are processed just as in normal text (each identifier - currently defined as a macro name is replaced by its replacement list of preprocessing - tokens). The directive resulting after all replacements shall match one of the two - previous forms and is then processed as appropriate. - - - - -[page 171] - - 6.10.5 Error directive - Semantics -1 A preprocessing directive of the form - # error pp-tokensopt new-line - causes the implementation to produce a diagnostic message that includes the specified - sequence of preprocessing tokens. - 6.10.6 Pragma directive - Semantics -1 A preprocessing directive of the form - # pragma pp-tokensopt new-line - where the preprocessing token STDC does not immediately follow pragma in the - directive (prior to any macro replacement)172) causes the implementation to behave in an - implementation-defined manner. The behavior might cause translation to fail or cause the - translator or the resulting program to behave in a non-conforming manner. Any such - pragma that is not recognized by the implementation is ignored. -2 If the preprocessing token STDC does immediately follow pragma in the directive (prior - to any macro replacement), then no macro replacement is performed on the directive, and - the directive shall have one of the following forms173) whose meanings are described - elsewhere: - #pragma STDC FP_CONTRACT on-off-switch - #pragma STDC FENV_ACCESS on-off-switch - #pragma STDC CX_LIMITED_RANGE on-off-switch - on-off-switch: one of - ON OFF DEFAULT - Forward references: the FP_CONTRACT pragma (7.12.2), the FENV_ACCESS pragma - (7.6.1), the CX_LIMITED_RANGE pragma (7.3.4). - - - - - 172) An implementation is not required to perform macro replacement in pragmas, but it is permitted - except for in standard pragmas (where STDC immediately follows pragma). If the result of macro - replacement in a non-standard pragma has the same form as a standard pragma, the behavior is still - implementation-defined; an implementation is permitted to behave as if it were the standard pragma, - but is not required to. - 173) See ''future language directions'' (6.11.8). - -[page 172] - - 6.10.7 Null directive - Semantics -1 A preprocessing directive of the form - # new-line - has no effect. - 6.10.8 Predefined macro names -1 The values of the predefined macros listed in the following subclauses174) (except for - __FILE__ and __LINE__) remain constant throughout the translation unit. -2 None of these macro names, nor the identifier defined, shall be the subject of a - #define or a #undef preprocessing directive. Any other predefined macro names - shall begin with a leading underscore followed by an uppercase letter or a second - underscore. -3 The implementation shall not predefine the macro __cplusplus, nor shall it define it - in any standard header. - Forward references: standard headers (7.1.2). - 6.10.8.1 Mandatory macros -1 The following macro names shall be defined by the implementation: - __DATE__ The date of translation of the preprocessing translation unit: a character - string literal of the form "Mmm dd yyyy", where the names of the - months are the same as those generated by the asctime function, and the - first character of dd is a space character if the value is less than 10. If the - date of translation is not available, an implementation-defined valid date - shall be supplied. - __FILE__ The presumed name of the current source file (a character string literal).175) - __LINE__ The presumed line number (within the current source file) of the current - source line (an integer constant).175) - __STDC__ The integer constant 1, intended to indicate a conforming implementation. - __STDC_HOSTED__ The integer constant 1 if the implementation is a hosted - implementation or the integer constant 0 if it is not. - - - - - 174) See ''future language directions'' (6.11.9). - 175) The presumed source file name and line number can be changed by the #line directive. - -[page 173] - - __STDC_VERSION__ The integer constant 201ymmL.176) - __TIME__ The time of translation of the preprocessing translation unit: a character - string literal of the form "hh:mm:ss" as in the time generated by the - asctime function. If the time of translation is not available, an - implementation-defined valid time shall be supplied. - Forward references: the asctime function (7.26.3.1). - 6.10.8.2 Environment macros -1 The following macro names are conditionally defined by the implementation: - __STDC_ISO_10646__ An integer constant of the form yyyymmL (for example, - 199712L). If this symbol is defined, then every character in the Unicode - required set, when stored in an object of type wchar_t, has the same - value as the short identifier of that character. The Unicode required set - consists of all the characters that are defined by ISO/IEC 10646, along with - all amendments and technical corrigenda, as of the specified year and - month. If some other encoding is used, the macro shall not be defined and - the actual encoding used is implementation-defined. - __STDC_MB_MIGHT_NEQ_WC__ The integer constant 1, intended to indicate that, in - the encoding for wchar_t, a member of the basic character set need not - have a code value equal to its value when used as the lone character in an - integer character constant. - __STDC_UTF_16__ The integer constant 1, intended to indicate that values of type - char16_t are UTF-16 encoded. If some other encoding is used, the - macro shall not be defined and the actual encoding used is implementation- - defined. - __STDC_UTF_32__ The integer constant 1, intended to indicate that values of type - char32_t are UTF-32 encoded. If some other encoding is used, the - macro shall not be defined and the actual encoding used is implementation- - defined. - Forward references: common definitions (7.19), unicode utilities (7.27). - - - - - 176) This macro was not specified in ISO/IEC 9899:1990 and was specified as 199409L in - ISO/IEC 9899/AMD1:1995 and as 199901L in ISO/IEC 9899:1999. The intention is that this will - remain an integer constant of type long int that is increased with each revision of this International - Standard. - -[page 174] - - 6.10.8.3 Conditional feature macros -1 The following macro names are conditionally defined by the implementation: - __STDC_ANALYZABLE__ The integer constant 1, intended to indicate conformance to - the specifications in annex L (Analyzability). - __STDC_IEC_559__ The integer constant 1, intended to indicate conformance to the - specifications in annex F (IEC 60559 floating-point arithmetic). - __STDC_IEC_559_COMPLEX__ The integer constant 1, intended to indicate - adherence to the specifications in informative annex G (IEC 60559 - compatible complex arithmetic). - __STDC_LIB_EXT1__ The integer constant 201ymmL, intended to indicate support - for the extensions defined in annex K (Bounds-checking interfaces).177) - __STDC_NO_COMPLEX__ The integer constant 1, intended to indicate that the - implementation does not support complex types or the - header. - __STDC_NO_THREADS__ The integer constant 1, intended to indicate that the - implementation does not support atomic types (including the _Atomic - type qualifier and the header) or the - header. - __STDC_NO_VLA__ The integer constant 1, intended to indicate that the - implementation does not support variable length arrays or variably - modified types. - 6.10.9 Pragma operator - Semantics -1 A unary operator expression of the form: - _Pragma ( string-literal ) - is processed as follows: The string literal is destringized by deleting the L prefix, if - present, deleting the leading and trailing double-quotes, replacing each escape sequence - \" by a double-quote, and replacing each escape sequence \\ by a single backslash. The - resulting sequence of characters is processed through translation phase 3 to produce - preprocessing tokens that are executed as if they were the pp-tokens in a pragma - directive. The original four preprocessing tokens in the unary operator expression are - removed. - - - 177) The intention is that this will remain an integer constant of type long int that is increased with - each revision of this International Standard. - -[page 175] - -2 EXAMPLE A directive of the form: - #pragma listing on "..\listing.dir" - can also be expressed as: - _Pragma ( "listing on \"..\\listing.dir\"" ) - The latter form is processed in the same way whether it appears literally as shown, or results from macro - replacement, as in: - #define LISTING(x) PRAGMA(listing on #x) - #define PRAGMA(x) _Pragma(#x) - LISTING ( ..\listing.dir ) - - - - -[page 176] - - 6.11 Future language directions - 6.11.1 Floating types -1 Future standardization may include additional floating-point types, including those with - greater range, precision, or both than long double. - 6.11.2 Linkages of identifiers -1 Declaring an identifier with internal linkage at file scope without the static storage- - class specifier is an obsolescent feature. - 6.11.3 External names -1 Restriction of the significance of an external name to fewer than 255 characters - (considering each universal character name or extended source character as a single - character) is an obsolescent feature that is a concession to existing implementations. - 6.11.4 Character escape sequences -1 Lowercase letters as escape sequences are reserved for future standardization. Other - characters may be used in extensions. - 6.11.5 Storage-class specifiers -1 The placement of a storage-class specifier other than at the beginning of the declaration - specifiers in a declaration is an obsolescent feature. - 6.11.6 Function declarators -1 The use of function declarators with empty parentheses (not prototype-format parameter - type declarators) is an obsolescent feature. - 6.11.7 Function definitions -1 The use of function definitions with separate parameter identifier and declaration lists - (not prototype-format parameter type and identifier declarators) is an obsolescent feature. - 6.11.8 Pragma directives -1 Pragmas whose first preprocessing token is STDC are reserved for future standardization. - 6.11.9 Predefined macro names -1 Macro names beginning with __STDC_ are reserved for future standardization. - - - - -[page 177] - - - 7. Library - 7.1 Introduction - 7.1.1 Definitions of terms -1 A string is a contiguous sequence of characters terminated by and including the first null - character. The term multibyte string is sometimes used instead to emphasize special - processing given to multibyte characters contained in the string or to avoid confusion - with a wide string. A pointer to a string is a pointer to its initial (lowest addressed) - character. The length of a string is the number of bytes preceding the null character and - the value of a string is the sequence of the values of the contained characters, in order. -2 The decimal-point character is the character used by functions that convert floating-point - numbers to or from character sequences to denote the beginning of the fractional part of - such character sequences.178) It is represented in the text and examples by a period, but - may be changed by the setlocale function. -3 A null wide character is a wide character with code value zero. -4 A wide string is a contiguous sequence of wide characters terminated by and including - the first null wide character. A pointer to a wide string is a pointer to its initial (lowest - addressed) wide character. The length of a wide string is the number of wide characters - preceding the null wide character and the value of a wide string is the sequence of code - values of the contained wide characters, in order. -5 A shift sequence is a contiguous sequence of bytes within a multibyte string that - (potentially) causes a change in shift state (see 5.2.1.2). A shift sequence shall not have a - corresponding wide character; it is instead taken to be an adjunct to an adjacent multibyte - character.179) - Forward references: character handling (7.4), the setlocale function (7.11.1.1). - - - - - 178) The functions that make use of the decimal-point character are the numeric conversion functions - (7.22.1, 7.28.4.1) and the formatted input/output functions (7.21.6, 7.28.2). - 179) For state-dependent encodings, the values for MB_CUR_MAX and MB_LEN_MAX shall thus be large - enough to count all the bytes in any complete multibyte character plus at least one adjacent shift - sequence of maximum length. Whether these counts provide for more than one shift sequence is the - implementation's choice. - -[page 178] - - 7.1.2 Standard headers -1 Each library function is declared, with a type that includes a prototype, in a header,180) - whose contents are made available by the #include preprocessing directive. The - header declares a set of related functions, plus any necessary types and additional macros - needed to facilitate their use. Declarations of types described in this clause shall not - include type qualifiers, unless explicitly stated otherwise. -2 The standard headers are181) - - - - - - - -3 If a file with the same name as one of the above < and > delimited sequences, not - provided as part of the implementation, is placed in any of the standard places that are - searched for included source files, the behavior is undefined. -4 Standard headers may be included in any order; each may be included more than once in - a given scope, with no effect different from being included only once, except that the - effect of including depends on the definition of NDEBUG (see 7.2). If - used, a header shall be included outside of any external declaration or definition, and it - shall first be included before the first reference to any of the functions or objects it - declares, or to any of the types or macros it defines. However, if an identifier is declared - or defined in more than one header, the second and subsequent associated headers may be - included after the initial reference to the identifier. The program shall not have any - macros with names lexically identical to keywords currently defined prior to the - inclusion. -5 Any definition of an object-like macro described in this clause shall expand to code that is - fully protected by parentheses where necessary, so that it groups in an arbitrary - expression as if it were a single identifier. -6 Any declaration of a library function shall have external linkage. - - - - - 180) A header is not necessarily a source file, nor are the < and > delimited sequences in header names - necessarily valid source file names. - 181) The headers , , and are conditional features that - implementations need not support; see 6.10.8.3. - -[page 179] - -7 A summary of the contents of the standard headers is given in annex B. - Forward references: diagnostics (7.2). - 7.1.3 Reserved identifiers -1 Each header declares or defines all identifiers listed in its associated subclause, and - optionally declares or defines identifiers listed in its associated future library directions - subclause and identifiers which are always reserved either for any use or for use as file - scope identifiers. - -- All identifiers that begin with an underscore and either an uppercase letter or another - underscore are always reserved for any use. - -- All identifiers that begin with an underscore are always reserved for use as identifiers - with file scope in both the ordinary and tag name spaces. - -- Each macro name in any of the following subclauses (including the future library - directions) is reserved for use as specified if any of its associated headers is included; - unless explicitly stated otherwise (see 7.1.4). - -- All identifiers with external linkage in any of the following subclauses (including the - future library directions) and errno are always reserved for use as identifiers with - external linkage.182) - -- Each identifier with file scope listed in any of the following subclauses (including the - future library directions) is reserved for use as a macro name and as an identifier with - file scope in the same name space if any of its associated headers is included. -2 No other identifiers are reserved. If the program declares or defines an identifier in a - context in which it is reserved (other than as allowed by 7.1.4), or defines a reserved - identifier as a macro name, the behavior is undefined. -3 If the program removes (with #undef) any macro definition of an identifier in the first - group listed above, the behavior is undefined. - - - - - 182) The list of reserved identifiers with external linkage includes math_errhandling, setjmp, - va_copy, and va_end. - -[page 180] - - 7.1.4 Use of library functions -1 Each of the following statements applies unless explicitly stated otherwise in the detailed - descriptions that follow: If an argument to a function has an invalid value (such as a value - outside the domain of the function, or a pointer outside the address space of the program, - or a null pointer, or a pointer to non-modifiable storage when the corresponding - parameter is not const-qualified) or a type (after promotion) not expected by a function - with variable number of arguments, the behavior is undefined. If a function argument is - described as being an array, the pointer actually passed to the function shall have a value - such that all address computations and accesses to objects (that would be valid if the - pointer did point to the first element of such an array) are in fact valid. Any function - declared in a header may be additionally implemented as a function-like macro defined in - the header, so if a library function is declared explicitly when its header is included, one - of the techniques shown below can be used to ensure the declaration is not affected by - such a macro. Any macro definition of a function can be suppressed locally by enclosing - the name of the function in parentheses, because the name is then not followed by the left - parenthesis that indicates expansion of a macro function name. For the same syntactic - reason, it is permitted to take the address of a library function even if it is also defined as - a macro.183) The use of #undef to remove any macro definition will also ensure that an - actual function is referred to. Any invocation of a library function that is implemented as - a macro shall expand to code that evaluates each of its arguments exactly once, fully - protected by parentheses where necessary, so it is generally safe to use arbitrary - expressions as arguments.184) Likewise, those function-like macros described in the - following subclauses may be invoked in an expression anywhere a function with a - compatible return type could be called.185) All object-like macros listed as expanding to - - - 183) This means that an implementation shall provide an actual function for each library function, even if it - also provides a macro for that function. - 184) Such macros might not contain the sequence points that the corresponding function calls do. - 185) Because external identifiers and some macro names beginning with an underscore are reserved, - implementations may provide special semantics for such names. For example, the identifier - _BUILTIN_abs could be used to indicate generation of in-line code for the abs function. Thus, the - appropriate header could specify - #define abs(x) _BUILTIN_abs(x) - for a compiler whose code generator will accept it. - In this manner, a user desiring to guarantee that a given library function such as abs will be a genuine - function may write - #undef abs - whether the implementation's header provides a macro implementation of abs or a built-in - implementation. The prototype for the function, which precedes and is hidden by any macro - definition, is thereby revealed also. - -[page 181] - - integer constant expressions shall additionally be suitable for use in #if preprocessing - directives. -2 Provided that a library function can be declared without reference to any type defined in a - header, it is also permissible to declare the function and use it without including its - associated header. -3 There is a sequence point immediately before a library function returns. -4 The functions in the standard library are not guaranteed to be reentrant and may modify - objects with static or thread storage duration.186) -5 Unless explicitly stated otherwise in the detailed descriptions that follow, library - functions shall prevent data races as follows: A library function shall not directly or - indirectly access objects accessible by threads other than the current thread unless the - objects are accessed directly or indirectly via the function's arguments. A library - function shall not directly or indirectly modify objects accessible by threads other than - the current thread unless the objects are accessed directly or indirectly via the function's - non-const arguments.187) Implementations may share their own internal objects between - threads if the objects are not visible to users and are protected against data races. -6 Unless otherwise specified, library functions shall perform all operations solely within the - current thread if those operations have effects that are visible to users.188) -7 EXAMPLE The function atoi may be used in any of several ways: - -- by use of its associated header (possibly generating a macro expansion) - #include - const char *str; - /* ... */ - i = atoi(str); - -- by use of its associated header (assuredly generating a true function reference) - - - - - 186) Thus, a signal handler cannot, in general, call standard library functions. - 187) This means, for example, that an implementation is not permitted to use a static object for internal - purposes without synchronization because it could cause a data race even in programs that do not - explicitly share objects between threads. - 188) This allows implementations to parallelize operations if there are no visible side effects. - -[page 182] - - #include - #undef atoi - const char *str; - /* ... */ - i = atoi(str); - or - #include - const char *str; - /* ... */ - i = (atoi)(str); --- by explicit declaration - extern int atoi(const char *); - const char *str; - /* ... */ - i = atoi(str); - - - - -[page 183] - - 7.2 Diagnostics -1 The header defines the assert and static_assert macros and - refers to another macro, - NDEBUG - which is not defined by . If NDEBUG is defined as a macro name at the - point in the source file where is included, the assert macro is defined - simply as - #define assert(ignore) ((void)0) - The assert macro is redefined according to the current state of NDEBUG each time that - is included. -2 The assert macro shall be implemented as a macro, not as an actual function. If the - macro definition is suppressed in order to access an actual function, the behavior is - undefined. -3 The macro - static_assert - expands to _Static_assert. - 7.2.1 Program diagnostics - 7.2.1.1 The assert macro - Synopsis -1 #include - void assert(scalar expression); - Description -2 The assert macro puts diagnostic tests into programs; it expands to a void expression. - When it is executed, if expression (which shall have a scalar type) is false (that is, - compares equal to 0), the assert macro writes information about the particular call that - failed (including the text of the argument, the name of the source file, the source line - number, and the name of the enclosing function -- the latter are respectively the values of - the preprocessing macros __FILE__ and __LINE__ and of the identifier - __func__) on the standard error stream in an implementation-defined format.189) It - then calls the abort function. - - - - 189) The message written might be of the form: - Assertion failed: expression, function abc, file xyz, line nnn. - - -[page 184] - - Returns -3 The assert macro returns no value. - Forward references: the abort function (7.22.4.1). - - - - -[page 185] - - 7.3 Complex arithmetic - 7.3.1 Introduction -1 The header defines macros and declares functions that support complex - arithmetic.190) -2 Implementations that define the macro __STDC_NO_COMPLEX__ need not provide - this header nor support any of its facilities. -3 Each synopsis specifies a family of functions consisting of a principal function with one - or more double complex parameters and a double complex or double return - value; and other functions with the same name but with f and l suffixes which are - corresponding functions with float and long double parameters and return values. -4 The macro - complex - expands to _Complex; the macro - _Complex_I - expands to a constant expression of type const float _Complex, with the value of - the imaginary unit.191) -5 The macros - imaginary - and - _Imaginary_I - are defined if and only if the implementation supports imaginary types;192) if defined, - they expand to _Imaginary and a constant expression of type const float - _Imaginary with the value of the imaginary unit. -6 The macro - I - expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not - defined, I shall expand to _Complex_I. -7 Notwithstanding the provisions of 7.1.3, a program may undefine and perhaps then - redefine the macros complex, imaginary, and I. - - 190) See ''future library directions'' (7.30.1). - 191) The imaginary unit is a number i such that i 2 = -1. - 192) A specification for imaginary types is in informative annex G. - -[page 186] - - Forward references: IEC 60559-compatible complex arithmetic (annex G). - 7.3.2 Conventions -1 Values are interpreted as radians, not degrees. An implementation may set errno but is - not required to. - 7.3.3 Branch cuts -1 Some of the functions below have branch cuts, across which the function is - discontinuous. For implementations with a signed zero (including all IEC 60559 - implementations) that follow the specifications of annex G, the sign of zero distinguishes - one side of a cut from another so the function is continuous (except for format - limitations) as the cut is approached from either side. For example, for the square root - function, which has a branch cut along the negative real axis, the top of the cut, with - imaginary part +0, maps to the positive imaginary axis, and the bottom of the cut, with - imaginary part -0, maps to the negative imaginary axis. -2 Implementations that do not support a signed zero (see annex F) cannot distinguish the - sides of branch cuts. These implementations shall map a cut so the function is continuous - as the cut is approached coming around the finite endpoint of the cut in a counter - clockwise direction. (Branch cuts for the functions specified here have just one finite - endpoint.) For example, for the square root function, coming counter clockwise around - the finite endpoint of the cut along the negative real axis approaches the cut from above, - so the cut maps to the positive imaginary axis. - 7.3.4 The CX_LIMITED_RANGE pragma - Synopsis -1 #include - #pragma STDC CX_LIMITED_RANGE on-off-switch - Description -2 The usual mathematical formulas for complex multiply, divide, and absolute value are - problematic because of their treatment of infinities and because of undue overflow and - underflow. The CX_LIMITED_RANGE pragma can be used to inform the - implementation that (where the state is ''on'') the usual mathematical formulas are - acceptable.193) The pragma can occur either outside external declarations or preceding all - explicit declarations and statements inside a compound statement. When outside external - declarations, the pragma takes effect from its occurrence until another - CX_LIMITED_RANGE pragma is encountered, or until the end of the translation unit. - When inside a compound statement, the pragma takes effect from its occurrence until - another CX_LIMITED_RANGE pragma is encountered (including within a nested - compound statement), or until the end of the compound statement; at the end of a - compound statement the state for the pragma is restored to its condition just before the - -[page 187] - - compound statement. If this pragma is used in any other context, the behavior is - undefined. The default state for the pragma is ''off''. - 7.3.5 Trigonometric functions - 7.3.5.1 The cacos functions - Synopsis -1 #include - double complex cacos(double complex z); - float complex cacosf(float complex z); - long double complex cacosl(long double complex z); - Description -2 The cacos functions compute the complex arc cosine of z, with branch cuts outside the - interval [-1, +1] along the real axis. - Returns -3 The cacos functions return the complex arc cosine value, in the range of a strip - mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the - real axis. - 7.3.5.2 The casin functions - Synopsis -1 #include - double complex casin(double complex z); - float complex casinf(float complex z); - long double complex casinl(long double complex z); - Description -2 The casin functions compute the complex arc sine of z, with branch cuts outside the - interval [-1, +1] along the real axis. - Returns -3 The casin functions return the complex arc sine value, in the range of a strip - mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2] - - 193) The purpose of the pragma is to allow the implementation to use the formulas: - (x + iy) x (u + iv) = (xu - yv) + i(yu + xv) - (x + iy) / (u + iv) = [(xu + yv) + i(yu - xv)]/(u2 + v 2 ) - | x + iy | = sqrt: x 2 + y 2 - ----- - where the programmer can determine they are safe. - -[page 188] - - along the real axis. - 7.3.5.3 The catan functions - Synopsis -1 #include - double complex catan(double complex z); - float complex catanf(float complex z); - long double complex catanl(long double complex z); - Description -2 The catan functions compute the complex arc tangent of z, with branch cuts outside the - interval [-i, +i] along the imaginary axis. - Returns -3 The catan functions return the complex arc tangent value, in the range of a strip - mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2] - along the real axis. - 7.3.5.4 The ccos functions - Synopsis -1 #include - double complex ccos(double complex z); - float complex ccosf(float complex z); - long double complex ccosl(long double complex z); - Description -2 The ccos functions compute the complex cosine of z. - Returns -3 The ccos functions return the complex cosine value. - 7.3.5.5 The csin functions - Synopsis -1 #include - double complex csin(double complex z); - float complex csinf(float complex z); - long double complex csinl(long double complex z); - Description -2 The csin functions compute the complex sine of z. - - - -[page 189] - - Returns -3 The csin functions return the complex sine value. - 7.3.5.6 The ctan functions - Synopsis -1 #include - double complex ctan(double complex z); - float complex ctanf(float complex z); - long double complex ctanl(long double complex z); - Description -2 The ctan functions compute the complex tangent of z. - Returns -3 The ctan functions return the complex tangent value. - 7.3.6 Hyperbolic functions - 7.3.6.1 The cacosh functions - Synopsis -1 #include - double complex cacosh(double complex z); - float complex cacoshf(float complex z); - long double complex cacoshl(long double complex z); - Description -2 The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch - cut at values less than 1 along the real axis. - Returns -3 The cacosh functions return the complex arc hyperbolic cosine value, in the range of a - half-strip of non-negative values along the real axis and in the interval [-ipi , +ipi ] along - the imaginary axis. - 7.3.6.2 The casinh functions - Synopsis -1 #include - double complex casinh(double complex z); - float complex casinhf(float complex z); - long double complex casinhl(long double complex z); - - - -[page 190] - - Description -2 The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts - outside the interval [-i, +i] along the imaginary axis. - Returns -3 The casinh functions return the complex arc hyperbolic sine value, in the range of a - strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2] - along the imaginary axis. - 7.3.6.3 The catanh functions - Synopsis -1 #include - double complex catanh(double complex z); - float complex catanhf(float complex z); - long double complex catanhl(long double complex z); - Description -2 The catanh functions compute the complex arc hyperbolic tangent of z, with branch - cuts outside the interval [-1, +1] along the real axis. - Returns -3 The catanh functions return the complex arc hyperbolic tangent value, in the range of a - strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2] - along the imaginary axis. - 7.3.6.4 The ccosh functions - Synopsis -1 #include - double complex ccosh(double complex z); - float complex ccoshf(float complex z); - long double complex ccoshl(long double complex z); - Description -2 The ccosh functions compute the complex hyperbolic cosine of z. - Returns -3 The ccosh functions return the complex hyperbolic cosine value. - - - - -[page 191] - - 7.3.6.5 The csinh functions - Synopsis -1 #include - double complex csinh(double complex z); - float complex csinhf(float complex z); - long double complex csinhl(long double complex z); - Description -2 The csinh functions compute the complex hyperbolic sine of z. - Returns -3 The csinh functions return the complex hyperbolic sine value. - 7.3.6.6 The ctanh functions - Synopsis -1 #include - double complex ctanh(double complex z); - float complex ctanhf(float complex z); - long double complex ctanhl(long double complex z); - Description -2 The ctanh functions compute the complex hyperbolic tangent of z. - Returns -3 The ctanh functions return the complex hyperbolic tangent value. - 7.3.7 Exponential and logarithmic functions - 7.3.7.1 The cexp functions - Synopsis -1 #include - double complex cexp(double complex z); - float complex cexpf(float complex z); - long double complex cexpl(long double complex z); - Description -2 The cexp functions compute the complex base-e exponential of z. - Returns -3 The cexp functions return the complex base-e exponential value. - - - -[page 192] - - 7.3.7.2 The clog functions - Synopsis -1 #include - double complex clog(double complex z); - float complex clogf(float complex z); - long double complex clogl(long double complex z); - Description -2 The clog functions compute the complex natural (base-e) logarithm of z, with a branch - cut along the negative real axis. - Returns -3 The clog functions return the complex natural logarithm value, in the range of a strip - mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the - imaginary axis. - 7.3.8 Power and absolute-value functions - 7.3.8.1 The cabs functions - Synopsis -1 #include - double cabs(double complex z); - float cabsf(float complex z); - long double cabsl(long double complex z); - Description -2 The cabs functions compute the complex absolute value (also called norm, modulus, or - magnitude) of z. - Returns -3 The cabs functions return the complex absolute value. - 7.3.8.2 The cpow functions - Synopsis -1 #include - double complex cpow(double complex x, double complex y); - float complex cpowf(float complex x, float complex y); - long double complex cpowl(long double complex x, - long double complex y); - - - - -[page 193] - - Description -2 The cpow functions compute the complex power function xy , with a branch cut for the - first parameter along the negative real axis. - Returns -3 The cpow functions return the complex power function value. - 7.3.8.3 The csqrt functions - Synopsis -1 #include - double complex csqrt(double complex z); - float complex csqrtf(float complex z); - long double complex csqrtl(long double complex z); - Description -2 The csqrt functions compute the complex square root of z, with a branch cut along the - negative real axis. - Returns -3 The csqrt functions return the complex square root value, in the range of the right half- - plane (including the imaginary axis). - 7.3.9 Manipulation functions - 7.3.9.1 The carg functions - Synopsis -1 #include - double carg(double complex z); - float cargf(float complex z); - long double cargl(long double complex z); - Description -2 The carg functions compute the argument (also called phase angle) of z, with a branch - cut along the negative real axis. - Returns -3 The carg functions return the value of the argument in the interval [-pi , +pi ]. - - - - -[page 194] - - 7.3.9.2 The cimag functions - Synopsis -1 #include - double cimag(double complex z); - float cimagf(float complex z); - long double cimagl(long double complex z); - Description -2 The cimag functions compute the imaginary part of z.194) - Returns -3 The cimag functions return the imaginary part value (as a real). - 7.3.9.3 The CMPLX macros - Synopsis -1 #include - double complex CMPLX(double x, double y); - float complex CMPLXF(float x, float y); - long double complex CMPLXL(long double x, long double y); - Description -2 The CMPLX macros expand to an expression of the specified complex type, with the real - part having the (converted) value of x and the imaginary part having the (converted) - value of y. - Recommended practice -3 The resulting expression should be suitable for use as an initializer for an object with - static or thread storage duration, provided both arguments are likewise suitable. - Returns -4 The CMPLX macros return the complex value x + i y. -5 NOTE These macros act as if the implementation supported imaginary types and the definitions were: - #define CMPLX(x, y) ((double complex)((double)(x) + \ - _Imaginary_I * (double)(y))) - #define CMPLXF(x, y) ((float complex)((float)(x) + \ - _Imaginary_I * (float)(y))) - #define CMPLXL(x, y) ((long double complex)((long double)(x) + \ - _Imaginary_I * (long double)(y))) - - - - - 194) For a variable z of complex type, z == creal(z) + cimag(z)*I. - -[page 195] - - 7.3.9.4 The conj functions - Synopsis -1 #include - double complex conj(double complex z); - float complex conjf(float complex z); - long double complex conjl(long double complex z); - Description -2 The conj functions compute the complex conjugate of z, by reversing the sign of its - imaginary part. - Returns -3 The conj functions return the complex conjugate value. - 7.3.9.5 The cproj functions - Synopsis -1 #include - double complex cproj(double complex z); - float complex cprojf(float complex z); - long double complex cprojl(long double complex z); - Description -2 The cproj functions compute a projection of z onto the Riemann sphere: z projects to - z except that all complex infinities (even those with one infinite part and one NaN part) - project to positive infinity on the real axis. If z has an infinite part, then cproj(z) is - equivalent to - INFINITY + I * copysign(0.0, cimag(z)) - Returns -3 The cproj functions return the value of the projection onto the Riemann sphere. - 7.3.9.6 The creal functions - Synopsis -1 #include - double creal(double complex z); - float crealf(float complex z); - long double creall(long double complex z); - Description -2 The creal functions compute the real part of z.195) - - -[page 196] - - Returns -3 The creal functions return the real part value. - - - - - 195) For a variable z of complex type, z == creal(z) + cimag(z)*I. - -[page 197] - - 7.4 Character handling -1 The header declares several functions useful for classifying and mapping - characters.196) In all cases the argument is an int, the value of which shall be - representable as an unsigned char or shall equal the value of the macro EOF. If the - argument has any other value, the behavior is undefined. -2 The behavior of these functions is affected by the current locale. Those functions that - have locale-specific aspects only when not in the "C" locale are noted below. -3 The term printing character refers to a member of a locale-specific set of characters, each - of which occupies one printing position on a display device; the term control character - refers to a member of a locale-specific set of characters that are not printing - characters.197) All letters and digits are printing characters. - Forward references: EOF (7.21.1), localization (7.11). - 7.4.1 Character classification functions -1 The functions in this subclause return nonzero (true) if and only if the value of the - argument c conforms to that in the description of the function. - 7.4.1.1 The isalnum function - Synopsis -1 #include - int isalnum(int c); - Description -2 The isalnum function tests for any character for which isalpha or isdigit is true. - 7.4.1.2 The isalpha function - Synopsis -1 #include - int isalpha(int c); - Description -2 The isalpha function tests for any character for which isupper or islower is true, - or any character that is one of a locale-specific set of alphabetic characters for which - - - - 196) See ''future library directions'' (7.30.2). - 197) In an implementation that uses the seven-bit US ASCII character set, the printing characters are those - whose values lie from 0x20 (space) through 0x7E (tilde); the control characters are those whose - values lie from 0 (NUL) through 0x1F (US), and the character 0x7F (DEL). - -[page 198] - - none of iscntrl, isdigit, ispunct, or isspace is true.198) In the "C" locale, - isalpha returns true only for the characters for which isupper or islower is true. - 7.4.1.3 The isblank function - Synopsis -1 #include - int isblank(int c); - Description -2 The isblank function tests for any character that is a standard blank character or is one - of a locale-specific set of characters for which isspace is true and that is used to - separate words within a line of text. The standard blank characters are the following: - space (' '), and horizontal tab ('\t'). In the "C" locale, isblank returns true only - for the standard blank characters. - 7.4.1.4 The iscntrl function - Synopsis -1 #include - int iscntrl(int c); - Description -2 The iscntrl function tests for any control character. - 7.4.1.5 The isdigit function - Synopsis -1 #include - int isdigit(int c); - Description -2 The isdigit function tests for any decimal-digit character (as defined in 5.2.1). - 7.4.1.6 The isgraph function - Synopsis -1 #include - int isgraph(int c); - - - - - 198) The functions islower and isupper test true or false separately for each of these additional - characters; all four combinations are possible. - -[page 199] - - Description -2 The isgraph function tests for any printing character except space (' '). - 7.4.1.7 The islower function - Synopsis -1 #include - int islower(int c); - Description -2 The islower function tests for any character that is a lowercase letter or is one of a - locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or - isspace is true. In the "C" locale, islower returns true only for the lowercase - letters (as defined in 5.2.1). - 7.4.1.8 The isprint function - Synopsis -1 #include - int isprint(int c); - Description -2 The isprint function tests for any printing character including space (' '). - 7.4.1.9 The ispunct function - Synopsis -1 #include - int ispunct(int c); - Description -2 The ispunct function tests for any printing character that is one of a locale-specific set - of punctuation characters for which neither isspace nor isalnum is true. In the "C" - locale, ispunct returns true for every printing character for which neither isspace - nor isalnum is true. - 7.4.1.10 The isspace function - Synopsis -1 #include - int isspace(int c); - Description -2 The isspace function tests for any character that is a standard white-space character or - is one of a locale-specific set of characters for which isalnum is false. The standard - -[page 200] - - white-space characters are the following: space (' '), form feed ('\f'), new-line - ('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v'). In the - "C" locale, isspace returns true only for the standard white-space characters. - 7.4.1.11 The isupper function - Synopsis -1 #include - int isupper(int c); - Description -2 The isupper function tests for any character that is an uppercase letter or is one of a - locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or - isspace is true. In the "C" locale, isupper returns true only for the uppercase - letters (as defined in 5.2.1). - 7.4.1.12 The isxdigit function - Synopsis -1 #include - int isxdigit(int c); - Description -2 The isxdigit function tests for any hexadecimal-digit character (as defined in 6.4.4.1). - 7.4.2 Character case mapping functions - 7.4.2.1 The tolower function - Synopsis -1 #include - int tolower(int c); - Description -2 The tolower function converts an uppercase letter to a corresponding lowercase letter. - Returns -3 If the argument is a character for which isupper is true and there are one or more - corresponding characters, as specified by the current locale, for which islower is true, - the tolower function returns one of the corresponding characters (always the same one - for any given locale); otherwise, the argument is returned unchanged. - - - - -[page 201] - - 7.4.2.2 The toupper function - Synopsis -1 #include - int toupper(int c); - Description -2 The toupper function converts a lowercase letter to a corresponding uppercase letter. - Returns -3 If the argument is a character for which islower is true and there are one or more - corresponding characters, as specified by the current locale, for which isupper is true, - the toupper function returns one of the corresponding characters (always the same one - for any given locale); otherwise, the argument is returned unchanged. - - - - -[page 202] - - 7.5 Errors -1 The header defines several macros, all relating to the reporting of error - conditions. -2 The macros are - EDOM - EILSEQ - ERANGE - which expand to integer constant expressions with type int, distinct positive values, and - which are suitable for use in #if preprocessing directives; and - errno - which expands to a modifiable lvalue199) that has type int and thread local storage - duration, the value of which is set to a positive error number by several library functions. - If a macro definition is suppressed in order to access an actual object, or a program - defines an identifier with the name errno, the behavior is undefined. -3 The value of errno in the initial thread is zero at program startup (the initial value of - errno in other threads is an indeterminate value), but is never set to zero by any library - function.200) The value of errno may be set to nonzero by a library function call - whether or not there is an error, provided the use of errno is not documented in the - description of the function in this International Standard. -4 Additional macro definitions, beginning with E and a digit or E and an uppercase - letter,201) may also be specified by the implementation. - - - - - 199) The macro errno need not be the identifier of an object. It might expand to a modifiable lvalue - resulting from a function call (for example, *errno()). - 200) Thus, a program that uses errno for error checking should set it to zero before a library function call, - then inspect it before a subsequent library function call. Of course, a library function can save the - value of errno on entry and then set it to zero, as long as the original value is restored if errno's - value is still zero just before the return. - 201) See ''future library directions'' (7.30.3). - -[page 203] - - 7.6 Floating-point environment -1 The header defines several macros, and declares types and functions that - provide access to the floating-point environment. The floating-point environment refers - collectively to any floating-point status flags and control modes supported by the - implementation.202) A floating-point status flag is a system variable whose value is set - (but never cleared) when a floating-point exception is raised, which occurs as a side effect - of exceptional floating-point arithmetic to provide auxiliary information.203) A floating- - point control mode is a system variable whose value may be set by the user to affect the - subsequent behavior of floating-point arithmetic. -2 The floating-point environment has thread storage duration. The initial state for a - thread's floating-point environment is the current state of the floating-point environment - of the thread that creates it at the time of creation. -3 Certain programming conventions support the intended model of use for the floating- - point environment:204) - -- a function call does not alter its caller's floating-point control modes, clear its caller's - floating-point status flags, nor depend on the state of its caller's floating-point status - flags unless the function is so documented; - -- a function call is assumed to require default floating-point control modes, unless its - documentation promises otherwise; - -- a function call is assumed to have the potential for raising floating-point exceptions, - unless its documentation promises otherwise. -4 The type - fenv_t - represents the entire floating-point environment. -5 The type - fexcept_t - represents the floating-point status flags collectively, including any status the - implementation associates with the flags. - - - 202) This header is designed to support the floating-point exception status flags and directed-rounding - control modes required by IEC 60559, and other similar floating-point state information. Also it is - designed to facilitate code portability among all systems. - 203) A floating-point status flag is not an object and can be set more than once within an expression. - 204) With these conventions, a programmer can safely assume default floating-point control modes (or be - unaware of them). The responsibilities associated with accessing the floating-point environment fall - on the programmer or program that does so explicitly. - -[page 204] - -6 Each of the macros - FE_DIVBYZERO - FE_INEXACT - FE_INVALID - FE_OVERFLOW - FE_UNDERFLOW - is defined if and only if the implementation supports the floating-point exception by - means of the functions in 7.6.2.205) Additional implementation-defined floating-point - exceptions, with macro definitions beginning with FE_ and an uppercase letter, may also - be specified by the implementation. The defined macros expand to integer constant - expressions with values such that bitwise ORs of all combinations of the macros result in - distinct values, and furthermore, bitwise ANDs of all combinations of the macros result in - zero.206) -7 The macro - FE_ALL_EXCEPT - is simply the bitwise OR of all floating-point exception macros defined by the - implementation. If no such macros are defined, FE_ALL_EXCEPT shall be defined as 0. -8 Each of the macros - FE_DOWNWARD - FE_TONEAREST - FE_TOWARDZERO - FE_UPWARD - is defined if and only if the implementation supports getting and setting the represented - rounding direction by means of the fegetround and fesetround functions. - Additional implementation-defined rounding directions, with macro definitions beginning - with FE_ and an uppercase letter, may also be specified by the implementation. The - defined macros expand to integer constant expressions whose values are distinct - nonnegative values.207) -9 The macro - - - - 205) The implementation supports an exception if there are circumstances where a call to at least one of the - functions in 7.6.2, using the macro as the appropriate argument, will succeed. It is not necessary for - all the functions to succeed all the time. - 206) The macros should be distinct powers of two. - 207) Even though the rounding direction macros may expand to constants corresponding to the values of - FLT_ROUNDS, they are not required to do so. - -[page 205] - - FE_DFL_ENV - represents the default floating-point environment -- the one installed at program startup - -- and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to - functions that manage the floating-point environment. -10 Additional implementation-defined environments, with macro definitions beginning with - FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may - also be specified by the implementation. - 7.6.1 The FENV_ACCESS pragma - Synopsis -1 #include - #pragma STDC FENV_ACCESS on-off-switch - Description -2 The FENV_ACCESS pragma provides a means to inform the implementation when a - program might access the floating-point environment to test floating-point status flags or - run under non-default floating-point control modes.208) The pragma shall occur either - outside external declarations or preceding all explicit declarations and statements inside a - compound statement. When outside external declarations, the pragma takes effect from - its occurrence until another FENV_ACCESS pragma is encountered, or until the end of - the translation unit. When inside a compound statement, the pragma takes effect from its - occurrence until another FENV_ACCESS pragma is encountered (including within a - nested compound statement), or until the end of the compound statement; at the end of a - compound statement the state for the pragma is restored to its condition just before the - compound statement. If this pragma is used in any other context, the behavior is - undefined. If part of a program tests floating-point status flags, sets floating-point control - modes, or runs under non-default mode settings, but was translated with the state for the - FENV_ACCESS pragma ''off'', the behavior is undefined. The default state (''on'' or - ''off'') for the pragma is implementation-defined. (When execution passes from a part of - the program translated with FENV_ACCESS ''off'' to a part translated with - FENV_ACCESS ''on'', the state of the floating-point status flags is unspecified and the - floating-point control modes have their default settings.) - - - - - 208) The purpose of the FENV_ACCESS pragma is to allow certain optimizations that could subvert flag - tests and mode changes (e.g., global common subexpression elimination, code motion, and constant - folding). In general, if the state of FENV_ACCESS is ''off'', the translator can assume that default - modes are in effect and the flags are not tested. - -[page 206] - -3 EXAMPLE - #include - void f(double x) - { - #pragma STDC FENV_ACCESS ON - void g(double); - void h(double); - /* ... */ - g(x + 1); - h(x + 1); - /* ... */ - } -4 If the function g might depend on status flags set as a side effect of the first x + 1, or if the second - x + 1 might depend on control modes set as a side effect of the call to function g, then the program shall - contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.209) - - 7.6.2 Floating-point exceptions -1 The following functions provide access to the floating-point status flags.210) The int - input argument for the functions represents a subset of floating-point exceptions, and can - be zero or the bitwise OR of one or more floating-point exception macros, for example - FE_OVERFLOW | FE_INEXACT. For other argument values the behavior of these - functions is undefined. - 7.6.2.1 The feclearexcept function - Synopsis -1 #include - int feclearexcept(int excepts); - Description -2 The feclearexcept function attempts to clear the supported floating-point exceptions - represented by its argument. - Returns -3 The feclearexcept function returns zero if the excepts argument is zero or if all - the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value. - - - 209) The side effects impose a temporal ordering that requires two evaluations of x + 1. On the other - hand, without the #pragma STDC FENV_ACCESS ON pragma, and assuming the default state is - ''off'', just one evaluation of x + 1 would suffice. - 210) The functions fetestexcept, feraiseexcept, and feclearexcept support the basic - abstraction of flags that are either set or clear. An implementation may endow floating-point status - flags with more information -- for example, the address of the code which first raised the floating- - point exception; the functions fegetexceptflag and fesetexceptflag deal with the full - content of flags. - -[page 207] - - 7.6.2.2 The fegetexceptflag function - Synopsis -1 #include - int fegetexceptflag(fexcept_t *flagp, - int excepts); - Description -2 The fegetexceptflag function attempts to store an implementation-defined - representation of the states of the floating-point status flags indicated by the argument - excepts in the object pointed to by the argument flagp. - Returns -3 The fegetexceptflag function returns zero if the representation was successfully - stored. Otherwise, it returns a nonzero value. - 7.6.2.3 The feraiseexcept function - Synopsis -1 #include - int feraiseexcept(int excepts); - Description -2 The feraiseexcept function attempts to raise the supported floating-point exceptions - represented by its argument.211) The order in which these floating-point exceptions are - raised is unspecified, except as stated in F.8.6. Whether the feraiseexcept function - additionally raises the ''inexact'' floating-point exception whenever it raises the - ''overflow'' or ''underflow'' floating-point exception is implementation-defined. - Returns -3 The feraiseexcept function returns zero if the excepts argument is zero or if all - the specified exceptions were successfully raised. Otherwise, it returns a nonzero value. - - - - - 211) The effect is intended to be similar to that of floating-point exceptions raised by arithmetic operations. - Hence, enabled traps for floating-point exceptions raised by this function are taken. The specification - in F.8.6 is in the same spirit. - -[page 208] - - 7.6.2.4 The fesetexceptflag function - Synopsis -1 #include - int fesetexceptflag(const fexcept_t *flagp, - int excepts); - Description -2 The fesetexceptflag function attempts to set the floating-point status flags - indicated by the argument excepts to the states stored in the object pointed to by - flagp. The value of *flagp shall have been set by a previous call to - fegetexceptflag whose second argument represented at least those floating-point - exceptions represented by the argument excepts. This function does not raise floating- - point exceptions, but only sets the state of the flags. - Returns -3 The fesetexceptflag function returns zero if the excepts argument is zero or if - all the specified flags were successfully set to the appropriate state. Otherwise, it returns - a nonzero value. - 7.6.2.5 The fetestexcept function - Synopsis -1 #include - int fetestexcept(int excepts); - Description -2 The fetestexcept function determines which of a specified subset of the floating- - point exception flags are currently set. The excepts argument specifies the floating- - point status flags to be queried.212) - Returns -3 The fetestexcept function returns the value of the bitwise OR of the floating-point - exception macros corresponding to the currently set floating-point exceptions included in - excepts. -4 EXAMPLE Call f if ''invalid'' is set, then g if ''overflow'' is set: - - - - - 212) This mechanism allows testing several floating-point exceptions with just one function call. - -[page 209] - - #include - /* ... */ - { - #pragma STDC FENV_ACCESS ON - int set_excepts; - feclearexcept(FE_INVALID | FE_OVERFLOW); - // maybe raise exceptions - set_excepts = fetestexcept(FE_INVALID | FE_OVERFLOW); - if (set_excepts & FE_INVALID) f(); - if (set_excepts & FE_OVERFLOW) g(); - /* ... */ - } - - 7.6.3 Rounding -1 The fegetround and fesetround functions provide control of rounding direction - modes. - 7.6.3.1 The fegetround function - Synopsis -1 #include - int fegetround(void); - Description -2 The fegetround function gets the current rounding direction. - Returns -3 The fegetround function returns the value of the rounding direction macro - representing the current rounding direction or a negative value if there is no such - rounding direction macro or the current rounding direction is not determinable. - 7.6.3.2 The fesetround function - Synopsis -1 #include - int fesetround(int round); - Description -2 The fesetround function establishes the rounding direction represented by its - argument round. If the argument is not equal to the value of a rounding direction macro, - the rounding direction is not changed. - Returns -3 The fesetround function returns zero if and only if the requested rounding direction - was established. - - -[page 210] - -4 EXAMPLE Save, set, and restore the rounding direction. Report an error and abort if setting the - rounding direction fails. - #include - #include - void f(int round_dir) - { - #pragma STDC FENV_ACCESS ON - int save_round; - int setround_ok; - save_round = fegetround(); - setround_ok = fesetround(round_dir); - assert(setround_ok == 0); - /* ... */ - fesetround(save_round); - /* ... */ - } - - 7.6.4 Environment -1 The functions in this section manage the floating-point environment -- status flags and - control modes -- as one entity. - 7.6.4.1 The fegetenv function - Synopsis -1 #include - int fegetenv(fenv_t *envp); - Description -2 The fegetenv function attempts to store the current floating-point environment in the - object pointed to by envp. - Returns -3 The fegetenv function returns zero if the environment was successfully stored. - Otherwise, it returns a nonzero value. - 7.6.4.2 The feholdexcept function - Synopsis -1 #include - int feholdexcept(fenv_t *envp); - Description -2 The feholdexcept function saves the current floating-point environment in the object - pointed to by envp, clears the floating-point status flags, and then installs a non-stop - (continue on floating-point exceptions) mode, if available, for all floating-point - exceptions.213) - -[page 211] - - Returns -3 The feholdexcept function returns zero if and only if non-stop floating-point - exception handling was successfully installed. - 7.6.4.3 The fesetenv function - Synopsis -1 #include - int fesetenv(const fenv_t *envp); - Description -2 The fesetenv function attempts to establish the floating-point environment represented - by the object pointed to by envp. The argument envp shall point to an object set by a - call to fegetenv or feholdexcept, or equal a floating-point environment macro. - Note that fesetenv merely installs the state of the floating-point status flags - represented through its argument, and does not raise these floating-point exceptions. - Returns -3 The fesetenv function returns zero if the environment was successfully established. - Otherwise, it returns a nonzero value. - 7.6.4.4 The feupdateenv function - Synopsis -1 #include - int feupdateenv(const fenv_t *envp); - Description -2 The feupdateenv function attempts to save the currently raised floating-point - exceptions in its automatic storage, install the floating-point environment represented by - the object pointed to by envp, and then raise the saved floating-point exceptions. The - argument envp shall point to an object set by a call to feholdexcept or fegetenv, - or equal a floating-point environment macro. - Returns -3 The feupdateenv function returns zero if all the actions were successfully carried out. - Otherwise, it returns a nonzero value. - - - - - 213) IEC 60559 systems have a default non-stop mode, and typically at least one other mode for trap - handling or aborting; if the system provides only the non-stop mode then installing it is trivial. For - such systems, the feholdexcept function can be used in conjunction with the feupdateenv - function to write routines that hide spurious floating-point exceptions from their callers. - -[page 212] - -4 EXAMPLE Hide spurious underflow floating-point exceptions: - #include - double f(double x) - { - #pragma STDC FENV_ACCESS ON - double result; - fenv_t save_env; - if (feholdexcept(&save_env)) - return /* indication of an environmental problem */; - // compute result - if (/* test spurious underflow */) - if (feclearexcept(FE_UNDERFLOW)) - return /* indication of an environmental problem */; - if (feupdateenv(&save_env)) - return /* indication of an environmental problem */; - return result; - } - - - - -[page 213] - - 7.7 Characteristics of floating types -1 The header defines several macros that expand to various limits and - parameters of the standard floating-point types. -2 The macros, their meanings, and the constraints (or restrictions) on their values are listed - in 5.2.4.2.2. - - - - -[page 214] - - 7.8 Format conversion of integer types -1 The header includes the header and extends it with - additional facilities provided by hosted implementations. -2 It declares functions for manipulating greatest-width integers and converting numeric - character strings to greatest-width integers, and it declares the type - imaxdiv_t - which is a structure type that is the type of the value returned by the imaxdiv function. - For each type declared in , it defines corresponding macros for conversion - specifiers for use with the formatted input/output functions.214) - Forward references: integer types (7.20), formatted input/output - functions (7.21.6), formatted wide character input/output functions (7.28.2). - 7.8.1 Macros for format specifiers -1 Each of the following object-like macros expands to a character string literal containing a - conversion specifier, possibly modified by a length modifier, suitable for use within the - format argument of a formatted input/output function when converting the corresponding - integer type. These macro names have the general form of PRI (character string literals - for the fprintf and fwprintf family) or SCN (character string literals for the - fscanf and fwscanf family),215) followed by the conversion specifier, followed by a - name corresponding to a similar type name in 7.20.1. In these names, N represents the - width of the type as described in 7.20.1. For example, PRIdFAST32 can be used in a - format string to print the value of an integer of type int_fast32_t. -2 The fprintf macros for signed integers are: - PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR - PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR -3 The fprintf macros for unsigned integers are: - PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR - PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR - PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR - PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR -4 The fscanf macros for signed integers are: - - - - 214) See ''future library directions'' (7.30.4). - 215) Separate macros are given for use with fprintf and fscanf functions because, in the general case, - different format specifiers may be required for fprintf and fscanf, even when the type is the - same. - -[page 215] - - SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR - SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR -5 The fscanf macros for unsigned integers are: - SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR - SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR - SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR -6 For each type that the implementation provides in , the corresponding - fprintf macros shall be defined and the corresponding fscanf macros shall be - defined unless the implementation does not have a suitable fscanf length modifier for - the type. -7 EXAMPLE - #include - #include - int main(void) - { - uintmax_t i = UINTMAX_MAX; // this type always exists - wprintf(L"The largest integer value is %020" - PRIxMAX "\n", i); - return 0; - } - - 7.8.2 Functions for greatest-width integer types - 7.8.2.1 The imaxabs function - Synopsis -1 #include - intmax_t imaxabs(intmax_t j); - Description -2 The imaxabs function computes the absolute value of an integer j. If the result cannot - be represented, the behavior is undefined.216) - Returns -3 The imaxabs function returns the absolute value. - - - - - 216) The absolute value of the most negative number cannot be represented in two's complement. - -[page 216] - - 7.8.2.2 The imaxdiv function - Synopsis -1 #include - imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom); - Description -2 The imaxdiv function computes numer / denom and numer % denom in a single - operation. - Returns -3 The imaxdiv function returns a structure of type imaxdiv_t comprising both the - quotient and the remainder. The structure shall contain (in either order) the members - quot (the quotient) and rem (the remainder), each of which has type intmax_t. If - either part of the result cannot be represented, the behavior is undefined. - 7.8.2.3 The strtoimax and strtoumax functions - Synopsis -1 #include - intmax_t strtoimax(const char * restrict nptr, - char ** restrict endptr, int base); - uintmax_t strtoumax(const char * restrict nptr, - char ** restrict endptr, int base); - Description -2 The strtoimax and strtoumax functions are equivalent to the strtol, strtoll, - strtoul, and strtoull functions, except that the initial portion of the string is - converted to intmax_t and uintmax_t representation, respectively. - Returns -3 The strtoimax and strtoumax functions return the converted value, if any. If no - conversion could be performed, zero is returned. If the correct value is outside the range - of representable values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned - (according to the return type and sign of the value, if any), and the value of the macro - ERANGE is stored in errno. - Forward references: the strtol, strtoll, strtoul, and strtoull functions - (7.22.1.4). - - - - -[page 217] - - 7.8.2.4 The wcstoimax and wcstoumax functions - Synopsis -1 #include // for wchar_t - #include - intmax_t wcstoimax(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - uintmax_t wcstoumax(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - Description -2 The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll, - wcstoul, and wcstoull functions except that the initial portion of the wide string is - converted to intmax_t and uintmax_t representation, respectively. - Returns -3 The wcstoimax function returns the converted value, if any. If no conversion could be - performed, zero is returned. If the correct value is outside the range of representable - values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned (according to the - return type and sign of the value, if any), and the value of the macro ERANGE is stored in - errno. - Forward references: the wcstol, wcstoll, wcstoul, and wcstoull functions - (7.28.4.1.2). - - - - -[page 218] - - 7.9 Alternative spellings -1 The header defines the following eleven macros (on the left) that expand - to the corresponding tokens (on the right): - and && - and_eq &= - bitand & - bitor | - compl ~ - not ! - not_eq != - or || - or_eq |= - xor ^ - xor_eq ^= - - - - -[page 219] - - 7.10 Sizes of integer types -1 The header defines several macros that expand to various limits and - parameters of the standard integer types. -2 The macros, their meanings, and the constraints (or restrictions) on their values are listed - in 5.2.4.2.1. - - - - -[page 220] - - 7.11 Localization -1 The header declares two functions, one type, and defines several macros. -2 The type is - struct lconv - which contains members related to the formatting of numeric values. The structure shall - contain at least the following members, in any order. The semantics of the members and - their normal ranges are explained in 7.11.2.1. In the "C" locale, the members shall have - the values specified in the comments. - char *decimal_point; // "." - char *thousands_sep; // "" - char *grouping; // "" - char *mon_decimal_point; // "" - char *mon_thousands_sep; // "" - char *mon_grouping; // "" - char *positive_sign; // "" - char *negative_sign; // "" - char *currency_symbol; // "" - char frac_digits; // CHAR_MAX - char p_cs_precedes; // CHAR_MAX - char n_cs_precedes; // CHAR_MAX - char p_sep_by_space; // CHAR_MAX - char n_sep_by_space; // CHAR_MAX - char p_sign_posn; // CHAR_MAX - char n_sign_posn; // CHAR_MAX - char *int_curr_symbol; // "" - char int_frac_digits; // CHAR_MAX - char int_p_cs_precedes; // CHAR_MAX - char int_n_cs_precedes; // CHAR_MAX - char int_p_sep_by_space; // CHAR_MAX - char int_n_sep_by_space; // CHAR_MAX - char int_p_sign_posn; // CHAR_MAX - char int_n_sign_posn; // CHAR_MAX - - - - -[page 221] - -3 The macros defined are NULL (described in 7.19); and - LC_ALL - LC_COLLATE - LC_CTYPE - LC_MONETARY - LC_NUMERIC - LC_TIME - which expand to integer constant expressions with distinct values, suitable for use as the - first argument to the setlocale function.217) Additional macro definitions, beginning - with the characters LC_ and an uppercase letter,218) may also be specified by the - implementation. - 7.11.1 Locale control - 7.11.1.1 The setlocale function - Synopsis -1 #include - char *setlocale(int category, const char *locale); - Description -2 The setlocale function selects the appropriate portion of the program's locale as - specified by the category and locale arguments. The setlocale function may be - used to change or query the program's entire current locale or portions thereof. The value - LC_ALL for category names the program's entire locale; the other values for - category name only a portion of the program's locale. LC_COLLATE affects the - behavior of the strcoll and strxfrm functions. LC_CTYPE affects the behavior of - the character handling functions219) and the multibyte and wide character functions. - LC_MONETARY affects the monetary formatting information returned by the - localeconv function. LC_NUMERIC affects the decimal-point character for the - formatted input/output functions and the string conversion functions, as well as the - nonmonetary formatting information returned by the localeconv function. LC_TIME - affects the behavior of the strftime and wcsftime functions. -3 A value of "C" for locale specifies the minimal environment for C translation; a value - of "" for locale specifies the locale-specific native environment. Other - implementation-defined strings may be passed as the second argument to setlocale. - - 217) ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C. - 218) See ''future library directions'' (7.30.5). - 219) The only functions in 7.4 whose behavior is not affected by the current locale are isdigit and - isxdigit. - -[page 222] - -4 At program startup, the equivalent of - setlocale(LC_ALL, "C"); - is executed. -5 A call to the setlocale function may introduce a data race with other calls to the - setlocale function or with calls to functions that are affected by the current locale. - The implementation shall behave as if no library function calls the setlocale function. - Returns -6 If a pointer to a string is given for locale and the selection can be honored, the - setlocale function returns a pointer to the string associated with the specified - category for the new locale. If the selection cannot be honored, the setlocale - function returns a null pointer and the program's locale is not changed. -7 A null pointer for locale causes the setlocale function to return a pointer to the - string associated with the category for the program's current locale; the program's - locale is not changed.220) -8 The pointer to string returned by the setlocale function is such that a subsequent call - with that string value and its associated category will restore that part of the program's - locale. The string pointed to shall not be modified by the program, but may be - overwritten by a subsequent call to the setlocale function. - Forward references: formatted input/output functions (7.21.6), multibyte/wide - character conversion functions (7.22.7), multibyte/wide string conversion functions - (7.22.8), numeric conversion functions (7.22.1), the strcoll function (7.23.4.3), the - strftime function (7.26.3.5), the strxfrm function (7.23.4.5). - 7.11.2 Numeric formatting convention inquiry - 7.11.2.1 The localeconv function - Synopsis -1 #include - struct lconv *localeconv(void); - Description -2 The localeconv function sets the components of an object with type struct lconv - with values appropriate for the formatting of numeric quantities (monetary and otherwise) - according to the rules of the current locale. - - - - 220) The implementation shall arrange to encode in a string the various categories due to a heterogeneous - locale when category has the value LC_ALL. - -[page 223] - -3 The members of the structure with type char * are pointers to strings, any of which - (except decimal_point) can point to "", to indicate that the value is not available in - the current locale or is of zero length. Apart from grouping and mon_grouping, the - strings shall start and end in the initial shift state. The members with type char are - nonnegative numbers, any of which can be CHAR_MAX to indicate that the value is not - available in the current locale. The members include the following: - char *decimal_point - The decimal-point character used to format nonmonetary quantities. - char *thousands_sep - The character used to separate groups of digits before the decimal-point - character in formatted nonmonetary quantities. - char *grouping - A string whose elements indicate the size of each group of digits in - formatted nonmonetary quantities. - char *mon_decimal_point - The decimal-point used to format monetary quantities. - char *mon_thousands_sep - The separator for groups of digits before the decimal-point in formatted - monetary quantities. - char *mon_grouping - A string whose elements indicate the size of each group of digits in - formatted monetary quantities. - char *positive_sign - The string used to indicate a nonnegative-valued formatted monetary - quantity. - char *negative_sign - The string used to indicate a negative-valued formatted monetary quantity. - char *currency_symbol - The local currency symbol applicable to the current locale. - char frac_digits - The number of fractional digits (those after the decimal-point) to be - displayed in a locally formatted monetary quantity. - char p_cs_precedes - Set to 1 or 0 if the currency_symbol respectively precedes or - succeeds the value for a nonnegative locally formatted monetary quantity. - - - -[page 224] - -char n_cs_precedes - Set to 1 or 0 if the currency_symbol respectively precedes or - succeeds the value for a negative locally formatted monetary quantity. -char p_sep_by_space - Set to a value indicating the separation of the currency_symbol, the - sign string, and the value for a nonnegative locally formatted monetary - quantity. -char n_sep_by_space - Set to a value indicating the separation of the currency_symbol, the - sign string, and the value for a negative locally formatted monetary - quantity. -char p_sign_posn - Set to a value indicating the positioning of the positive_sign for a - nonnegative locally formatted monetary quantity. -char n_sign_posn - Set to a value indicating the positioning of the negative_sign for a - negative locally formatted monetary quantity. -char *int_curr_symbol - The international currency symbol applicable to the current locale. The - first three characters contain the alphabetic international currency symbol - in accordance with those specified in ISO 4217. The fourth character - (immediately preceding the null character) is the character used to separate - the international currency symbol from the monetary quantity. -char int_frac_digits - The number of fractional digits (those after the decimal-point) to be - displayed in an internationally formatted monetary quantity. -char int_p_cs_precedes - Set to 1 or 0 if the int_curr_symbol respectively precedes or - succeeds the value for a nonnegative internationally formatted monetary - quantity. -char int_n_cs_precedes - Set to 1 or 0 if the int_curr_symbol respectively precedes or - succeeds the value for a negative internationally formatted monetary - quantity. -char int_p_sep_by_space - Set to a value indicating the separation of the int_curr_symbol, the - sign string, and the value for a nonnegative internationally formatted - monetary quantity. -[page 225] - - char int_n_sep_by_space - Set to a value indicating the separation of the int_curr_symbol, the - sign string, and the value for a negative internationally formatted monetary - quantity. - char int_p_sign_posn - Set to a value indicating the positioning of the positive_sign for a - nonnegative internationally formatted monetary quantity. - char int_n_sign_posn - Set to a value indicating the positioning of the negative_sign for a - negative internationally formatted monetary quantity. -4 The elements of grouping and mon_grouping are interpreted according to the - following: - CHAR_MAX No further grouping is to be performed. - 0 The previous element is to be repeatedly used for the remainder of the - digits. - other The integer value is the number of digits that compose the current group. - The next element is examined to determine the size of the next group of - digits before the current group. -5 The values of p_sep_by_space, n_sep_by_space, int_p_sep_by_space, - and int_n_sep_by_space are interpreted according to the following: - 0 No space separates the currency symbol and value. - 1 If the currency symbol and sign string are adjacent, a space separates them from the - value; otherwise, a space separates the currency symbol from the value. - 2 If the currency symbol and sign string are adjacent, a space separates them; - otherwise, a space separates the sign string from the value. - For int_p_sep_by_space and int_n_sep_by_space, the fourth character of - int_curr_symbol is used instead of a space. -6 The values of p_sign_posn, n_sign_posn, int_p_sign_posn, and - int_n_sign_posn are interpreted according to the following: - 0 Parentheses surround the quantity and currency symbol. - 1 The sign string precedes the quantity and currency symbol. - 2 The sign string succeeds the quantity and currency symbol. - 3 The sign string immediately precedes the currency symbol. - 4 The sign string immediately succeeds the currency symbol. - - -[page 226] - -7 The implementation shall behave as if no library function calls the localeconv - function. - Returns -8 The localeconv function returns a pointer to the filled-in object. The structure - pointed to by the return value shall not be modified by the program, but may be - overwritten by a subsequent call to the localeconv function. In addition, calls to the - setlocale function with categories LC_ALL, LC_MONETARY, or LC_NUMERIC may - overwrite the contents of the structure. -9 EXAMPLE 1 The following table illustrates rules which may well be used by four countries to format - monetary quantities. - Local format International format - - Country Positive Negative Positive Negative - - Country1 1.234,56 mk -1.234,56 mk FIM 1.234,56 FIM -1.234,56 - Country2 L.1.234 -L.1.234 ITL 1.234 -ITL 1.234 - Country3 fl. 1.234,56 fl. -1.234,56 NLG 1.234,56 NLG -1.234,56 - Country4 SFrs.1,234.56 SFrs.1,234.56C CHF 1,234.56 CHF 1,234.56C -10 For these four countries, the respective values for the monetary members of the structure returned by - localeconv could be: - Country1 Country2 Country3 Country4 - - mon_decimal_point "," "" "," "." - mon_thousands_sep "." "." "." "," - mon_grouping "\3" "\3" "\3" "\3" - positive_sign "" "" "" "" - negative_sign "-" "-" "-" "C" - currency_symbol "mk" "L." "\u0192" "SFrs." - frac_digits 2 0 2 2 - p_cs_precedes 0 1 1 1 - n_cs_precedes 0 1 1 1 - p_sep_by_space 1 0 1 0 - n_sep_by_space 1 0 2 0 - p_sign_posn 1 1 1 1 - n_sign_posn 1 1 4 2 - int_curr_symbol "FIM " "ITL " "NLG " "CHF " - int_frac_digits 2 0 2 2 - int_p_cs_precedes 1 1 1 1 - int_n_cs_precedes 1 1 1 1 - int_p_sep_by_space 1 1 1 1 - int_n_sep_by_space 2 1 2 1 - int_p_sign_posn 1 1 1 1 - int_n_sign_posn 4 1 4 2 - - - - -[page 227] - -11 EXAMPLE 2 The following table illustrates how the cs_precedes, sep_by_space, and sign_posn members - affect the formatted value. - p_sep_by_space - - p_cs_precedes p_sign_posn 0 1 2 - - 0 0 (1.25$) (1.25 $) (1.25$) - 1 +1.25$ +1.25 $ + 1.25$ - 2 1.25$+ 1.25 $+ 1.25$ + - 3 1.25+$ 1.25 +$ 1.25+ $ - 4 1.25$+ 1.25 $+ 1.25$ + - - 1 0 ($1.25) ($ 1.25) ($1.25) - 1 +$1.25 +$ 1.25 + $1.25 - 2 $1.25+ $ 1.25+ $1.25 + - 3 +$1.25 +$ 1.25 + $1.25 - 4 $+1.25 $+ 1.25 $ +1.25 - - - - -[page 228] - - 7.12 Mathematics -1 The header declares two types and many mathematical functions and defines - several macros. Most synopses specify a family of functions consisting of a principal - function with one or more double parameters, a double return value, or both; and - other functions with the same name but with f and l suffixes, which are corresponding - functions with float and long double parameters, return values, or both.221) - Integer arithmetic functions and conversion functions are discussed later. -2 The types - float_t - double_t - are floating types at least as wide as float and double, respectively, and such that - double_t is at least as wide as float_t. If FLT_EVAL_METHOD equals 0, - float_t and double_t are float and double, respectively; if - FLT_EVAL_METHOD equals 1, they are both double; if FLT_EVAL_METHOD equals - 2, they are both long double; and for other values of FLT_EVAL_METHOD, they are - otherwise implementation-defined.222) -3 The macro - HUGE_VAL - expands to a positive double constant expression, not necessarily representable as a - float. The macros - HUGE_VALF - HUGE_VALL - are respectively float and long double analogs of HUGE_VAL.223) -4 The macro - INFINITY - expands to a constant expression of type float representing positive or unsigned - infinity, if available; else to a positive constant of type float that overflows at - - - - 221) Particularly on systems with wide expression evaluation, a function might pass arguments - and return values in wider format than the synopsis prototype indicates. - 222) The types float_t and double_t are intended to be the implementation's most efficient types at - least as wide as float and double, respectively. For FLT_EVAL_METHOD equal 0, 1, or 2, the - type float_t is the narrowest type used by the implementation to evaluate floating expressions. - 223) HUGE_VAL, HUGE_VALF, and HUGE_VALL can be positive infinities in an implementation that - supports infinities. - -[page 229] - - translation time.224) -5 The macro - NAN - is defined if and only if the implementation supports quiet NaNs for the float type. It - expands to a constant expression of type float representing a quiet NaN. -6 The number classification macros - FP_INFINITE - FP_NAN - FP_NORMAL - FP_SUBNORMAL - FP_ZERO - represent the mutually exclusive kinds of floating-point values. They expand to integer - constant expressions with distinct values. Additional implementation-defined floating- - point classifications, with macro definitions beginning with FP_ and an uppercase letter, - may also be specified by the implementation. -7 The macro - FP_FAST_FMA - is optionally defined. If defined, it indicates that the fma function generally executes - about as fast as, or faster than, a multiply and an add of double operands.225) The - macros - FP_FAST_FMAF - FP_FAST_FMAL - are, respectively, float and long double analogs of FP_FAST_FMA. If defined, - these macros expand to the integer constant 1. -8 The macros - FP_ILOGB0 - FP_ILOGBNAN - expand to integer constant expressions whose values are returned by ilogb(x) if x is - zero or NaN, respectively. The value of FP_ILOGB0 shall be either INT_MIN or - -INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN. - - - 224) In this case, using INFINITY will violate the constraint in 6.4.4 and thus require a diagnostic. - 225) Typically, the FP_FAST_FMA macro is defined if and only if the fma function is implemented - directly with a hardware multiply-add instruction. Software implementations are expected to be - substantially slower. - -[page 230] - -9 The macros - MATH_ERRNO - MATH_ERREXCEPT - expand to the integer constants 1 and 2, respectively; the macro - math_errhandling - expands to an expression that has type int and the value MATH_ERRNO, - MATH_ERREXCEPT, or the bitwise OR of both. The value of math_errhandling is - constant for the duration of the program. It is unspecified whether - math_errhandling is a macro or an identifier with external linkage. If a macro - definition is suppressed or a program defines an identifier with the name - math_errhandling, the behavior is undefined. If the expression - math_errhandling & MATH_ERREXCEPT can be nonzero, the implementation - shall define the macros FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in - . - 7.12.1 Treatment of error conditions -1 The behavior of each of the functions in is specified for all representable - values of its input arguments, except where stated otherwise. Each function shall execute - as if it were a single operation without raising SIGFPE and without generating any of the - exceptions ''invalid'', ''divide-by-zero'', or ''overflow'' except to reflect the result of the - function. -2 For all functions, a domain error occurs if an input argument is outside the domain over - which the mathematical function is defined. The description of each function lists any - required domain errors; an implementation may define additional domain errors, provided - that such errors are consistent with the mathematical definition of the function.226) On a - domain error, the function returns an implementation-defined value; if the integer - expression math_errhandling & MATH_ERRNO is nonzero, the integer expression - errno acquires the value EDOM; if the integer expression math_errhandling & - MATH_ERREXCEPT is nonzero, the ''invalid'' floating-point exception is raised. -3 Similarly, a pole error (also known as a singularity or infinitary) occurs if the - mathematical function has an exact infinite result as the finite input argument(s) are - approached in the limit (for example, log(0.0)). The description of each function lists - any required pole errors; an implementation may define additional pole errors, provided - that such errors are consistent with the mathematical definition of the function. On a pole - error, the function returns an implementation-defined value; if the integer expression - - - 226) In an implementation that supports infinities, this allows an infinity as an argument to be a domain - error if the mathematical domain of the function does not include the infinity. - -[page 231] - - math_errhandling & MATH_ERRNO is nonzero, the integer expression errno - acquires the value ERANGE; if the integer expression math_errhandling & - MATH_ERREXCEPT is nonzero, the ''divide-by-zero'' floating-point exception is raised. -4 Likewise, a range error occurs if the mathematical result of the function cannot be - represented in an object of the specified type, due to extreme magnitude. -5 A floating result overflows if the magnitude of the mathematical result is finite but so - large that the mathematical result cannot be represented without extraordinary roundoff - error in an object of the specified type. If a floating result overflows and default rounding - is in effect, then the function returns the value of the macro HUGE_VAL, HUGE_VALF, or - HUGE_VALL according to the return type, with the same sign as the correct value of the - function; if the integer expression math_errhandling & MATH_ERRNO is nonzero, - the integer expression errno acquires the value ERANGE; if the integer expression - math_errhandling & MATH_ERREXCEPT is nonzero, the ''overflow'' floating- - point exception is raised. -6 The result underflows if the magnitude of the mathematical result is so small that the - mathematical result cannot be represented, without extraordinary roundoff error, in an - object of the specified type.227) If the result underflows, the function returns an - implementation-defined value whose magnitude is no greater than the smallest - normalized positive number in the specified type; if the integer expression - math_errhandling & MATH_ERRNO is nonzero, whether errno acquires the - value ERANGE is implementation-defined; if the integer expression - math_errhandling & MATH_ERREXCEPT is nonzero, whether the ''underflow'' - floating-point exception is raised is implementation-defined. -7 If a domain, pole, or range error occurs and the integer expression - math_errhandling & MATH_ERRNO is zero,228) then errno shall either be set to - the value corresponding to the error or left unmodified. If no such error occurs, errno - shall be left unmodified regardless of the setting of math_errhandling. - - - - - 227) The term underflow here is intended to encompass both ''gradual underflow'' as in IEC 60559 and - also ''flush-to-zero'' underflow. - 228) Math errors are being indicated by the floating-point exception flags rather than by errno. - -[page 232] - - 7.12.2 The FP_CONTRACT pragma - Synopsis -1 #include - #pragma STDC FP_CONTRACT on-off-switch - Description -2 The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the - state is ''off'') the implementation to contract expressions (6.5). Each pragma can occur - either outside external declarations or preceding all explicit declarations and statements - inside a compound statement. When outside external declarations, the pragma takes - effect from its occurrence until another FP_CONTRACT pragma is encountered, or until - the end of the translation unit. When inside a compound statement, the pragma takes - effect from its occurrence until another FP_CONTRACT pragma is encountered - (including within a nested compound statement), or until the end of the compound - statement; at the end of a compound statement the state for the pragma is restored to its - condition just before the compound statement. If this pragma is used in any other - context, the behavior is undefined. The default state (''on'' or ''off'') for the pragma is - implementation-defined. - 7.12.3 Classification macros -1 In the synopses in this subclause, real-floating indicates that the argument shall be an - expression of real floating type. - 7.12.3.1 The fpclassify macro - Synopsis -1 #include - int fpclassify(real-floating x); - Description -2 The fpclassify macro classifies its argument value as NaN, infinite, normal, - subnormal, zero, or into another implementation-defined category. First, an argument - represented in a format wider than its semantic type is converted to its semantic type. - Then classification is based on the type of the argument.229) - Returns -3 The fpclassify macro returns the value of the number classification macro - appropriate to the value of its argument. - - - 229) Since an expression can be evaluated with more range and precision than its type has, it is important to - know the type that classification is based on. For example, a normal long double value might - become subnormal when converted to double, and zero when converted to float. - -[page 233] - - 7.12.3.2 The isfinite macro - Synopsis -1 #include - int isfinite(real-floating x); - Description -2 The isfinite macro determines whether its argument has a finite value (zero, - subnormal, or normal, and not infinite or NaN). First, an argument represented in a - format wider than its semantic type is converted to its semantic type. Then determination - is based on the type of the argument. - Returns -3 The isfinite macro returns a nonzero value if and only if its argument has a finite - value. - 7.12.3.3 The isinf macro - Synopsis -1 #include - int isinf(real-floating x); - Description -2 The isinf macro determines whether its argument value is an infinity (positive or - negative). First, an argument represented in a format wider than its semantic type is - converted to its semantic type. Then determination is based on the type of the argument. - Returns -3 The isinf macro returns a nonzero value if and only if its argument has an infinite - value. - 7.12.3.4 The isnan macro - Synopsis -1 #include - int isnan(real-floating x); - Description -2 The isnan macro determines whether its argument value is a NaN. First, an argument - represented in a format wider than its semantic type is converted to its semantic type. - Then determination is based on the type of the argument.230) - - - 230) For the isnan macro, the type for determination does not matter unless the implementation supports - NaNs in the evaluation type but not in the semantic type. - -[page 234] - - Returns -3 The isnan macro returns a nonzero value if and only if its argument has a NaN value. - 7.12.3.5 The isnormal macro - Synopsis -1 #include - int isnormal(real-floating x); - Description -2 The isnormal macro determines whether its argument value is normal (neither zero, - subnormal, infinite, nor NaN). First, an argument represented in a format wider than its - semantic type is converted to its semantic type. Then determination is based on the type - of the argument. - Returns -3 The isnormal macro returns a nonzero value if and only if its argument has a normal - value. - 7.12.3.6 The signbit macro - Synopsis -1 #include - int signbit(real-floating x); - Description -2 The signbit macro determines whether the sign of its argument value is negative.231) - Returns -3 The signbit macro returns a nonzero value if and only if the sign of its argument value - is negative. - - - - - 231) The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is - unsigned, it is treated as positive. - -[page 235] - - 7.12.4 Trigonometric functions - 7.12.4.1 The acos functions - Synopsis -1 #include - double acos(double x); - float acosf(float x); - long double acosl(long double x); - Description -2 The acos functions compute the principal value of the arc cosine of x. A domain error - occurs for arguments not in the interval [-1, +1]. - Returns -3 The acos functions return arccos x in the interval [0, pi ] radians. - 7.12.4.2 The asin functions - Synopsis -1 #include - double asin(double x); - float asinf(float x); - long double asinl(long double x); - Description -2 The asin functions compute the principal value of the arc sine of x. A domain error - occurs for arguments not in the interval [-1, +1]. - Returns -3 The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians. - 7.12.4.3 The atan functions - Synopsis -1 #include - double atan(double x); - float atanf(float x); - long double atanl(long double x); - Description -2 The atan functions compute the principal value of the arc tangent of x. - - - - -[page 236] - - Returns -3 The atan functions return arctan x in the interval [-pi /2, +pi /2] radians. - 7.12.4.4 The atan2 functions - Synopsis -1 #include - double atan2(double y, double x); - float atan2f(float y, float x); - long double atan2l(long double y, long double x); - Description -2 The atan2 functions compute the value of the arc tangent of y/x, using the signs of both - arguments to determine the quadrant of the return value. A domain error may occur if - both arguments are zero. - Returns -3 The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians. - 7.12.4.5 The cos functions - Synopsis -1 #include - double cos(double x); - float cosf(float x); - long double cosl(long double x); - Description -2 The cos functions compute the cosine of x (measured in radians). - Returns -3 The cos functions return cos x. - 7.12.4.6 The sin functions - Synopsis -1 #include - double sin(double x); - float sinf(float x); - long double sinl(long double x); - Description -2 The sin functions compute the sine of x (measured in radians). - - - -[page 237] - - Returns -3 The sin functions return sin x. - 7.12.4.7 The tan functions - Synopsis -1 #include - double tan(double x); - float tanf(float x); - long double tanl(long double x); - Description -2 The tan functions return the tangent of x (measured in radians). - Returns -3 The tan functions return tan x. - 7.12.5 Hyperbolic functions - 7.12.5.1 The acosh functions - Synopsis -1 #include - double acosh(double x); - float acoshf(float x); - long double acoshl(long double x); - Description -2 The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain - error occurs for arguments less than 1. - Returns -3 The acosh functions return arcosh x in the interval [0, +(inf)]. - 7.12.5.2 The asinh functions - Synopsis -1 #include - double asinh(double x); - float asinhf(float x); - long double asinhl(long double x); - Description -2 The asinh functions compute the arc hyperbolic sine of x. - - -[page 238] - - Returns -3 The asinh functions return arsinh x. - 7.12.5.3 The atanh functions - Synopsis -1 #include - double atanh(double x); - float atanhf(float x); - long double atanhl(long double x); - Description -2 The atanh functions compute the arc hyperbolic tangent of x. A domain error occurs - for arguments not in the interval [-1, +1]. A pole error may occur if the argument equals - -1 or +1. - Returns -3 The atanh functions return artanh x. - 7.12.5.4 The cosh functions - Synopsis -1 #include - double cosh(double x); - float coshf(float x); - long double coshl(long double x); - Description -2 The cosh functions compute the hyperbolic cosine of x. A range error occurs if the - magnitude of x is too large. - Returns -3 The cosh functions return cosh x. - 7.12.5.5 The sinh functions - Synopsis -1 #include - double sinh(double x); - float sinhf(float x); - long double sinhl(long double x); - Description -2 The sinh functions compute the hyperbolic sine of x. A range error occurs if the - magnitude of x is too large. -[page 239] - - Returns -3 The sinh functions return sinh x. - 7.12.5.6 The tanh functions - Synopsis -1 #include - double tanh(double x); - float tanhf(float x); - long double tanhl(long double x); - Description -2 The tanh functions compute the hyperbolic tangent of x. - Returns -3 The tanh functions return tanh x. - 7.12.6 Exponential and logarithmic functions - 7.12.6.1 The exp functions - Synopsis -1 #include - double exp(double x); - float expf(float x); - long double expl(long double x); - Description -2 The exp functions compute the base-e exponential of x. A range error occurs if the - magnitude of x is too large. - Returns -3 The exp functions return ex . - 7.12.6.2 The exp2 functions - Synopsis -1 #include - double exp2(double x); - float exp2f(float x); - long double exp2l(long double x); - Description -2 The exp2 functions compute the base-2 exponential of x. A range error occurs if the - magnitude of x is too large. - -[page 240] - - Returns -3 The exp2 functions return 2x . - 7.12.6.3 The expm1 functions - Synopsis -1 #include - double expm1(double x); - float expm1f(float x); - long double expm1l(long double x); - Description -2 The expm1 functions compute the base-e exponential of the argument, minus 1. A range - error occurs if x is too large.232) - Returns -3 The expm1 functions return ex - 1. - 7.12.6.4 The frexp functions - Synopsis -1 #include - double frexp(double value, int *exp); - float frexpf(float value, int *exp); - long double frexpl(long double value, int *exp); - Description -2 The frexp functions break a floating-point number into a normalized fraction and an - integral power of 2. They store the integer in the int object pointed to by exp. - Returns -3 If value is not a floating-point number or if the integral power of 2 is outside the range - of int, the results are unspecified. Otherwise, the frexp functions return the value x, - such that x has a magnitude in the interval [1/2, 1) or zero, and value equals x x 2*exp . - If value is zero, both parts of the result are zero. - - - - - 232) For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1. - -[page 241] - - 7.12.6.5 The ilogb functions - Synopsis -1 #include - int ilogb(double x); - int ilogbf(float x); - int ilogbl(long double x); - Description -2 The ilogb functions extract the exponent of x as a signed int value. If x is zero they - compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is - a NaN they compute the value FP_ILOGBNAN; otherwise, they are equivalent to calling - the corresponding logb function and casting the returned value to type int. A domain - error or range error may occur if x is zero, infinite, or NaN. If the correct value is outside - the range of the return type, the numeric result is unspecified. - Returns -3 The ilogb functions return the exponent of x as a signed int value. - Forward references: the logb functions (7.12.6.11). - 7.12.6.6 The ldexp functions - Synopsis -1 #include - double ldexp(double x, int exp); - float ldexpf(float x, int exp); - long double ldexpl(long double x, int exp); - Description -2 The ldexp functions multiply a floating-point number by an integral power of 2. A - range error may occur. - Returns -3 The ldexp functions return x x 2exp . - 7.12.6.7 The log functions - Synopsis -1 #include - double log(double x); - float logf(float x); - long double logl(long double x); - - - -[page 242] - - Description -2 The log functions compute the base-e (natural) logarithm of x. A domain error occurs if - the argument is negative. A pole error may occur if the argument is zero. - Returns -3 The log functions return loge x. - 7.12.6.8 The log10 functions - Synopsis -1 #include - double log10(double x); - float log10f(float x); - long double log10l(long double x); - Description -2 The log10 functions compute the base-10 (common) logarithm of x. A domain error - occurs if the argument is negative. A pole error may occur if the argument is zero. - Returns -3 The log10 functions return log10 x. - 7.12.6.9 The log1p functions - Synopsis -1 #include - double log1p(double x); - float log1pf(float x); - long double log1pl(long double x); - Description -2 The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.233) - A domain error occurs if the argument is less than -1. A pole error may occur if the - argument equals -1. - Returns -3 The log1p functions return loge (1 + x). - - - - - 233) For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x). - -[page 243] - - 7.12.6.10 The log2 functions - Synopsis -1 #include - double log2(double x); - float log2f(float x); - long double log2l(long double x); - Description -2 The log2 functions compute the base-2 logarithm of x. A domain error occurs if the - argument is less than zero. A pole error may occur if the argument is zero. - Returns -3 The log2 functions return log2 x. - 7.12.6.11 The logb functions - Synopsis -1 #include - double logb(double x); - float logbf(float x); - long double logbl(long double x); - Description -2 The logb functions extract the exponent of x, as a signed integer value in floating-point - format. If x is subnormal it is treated as though it were normalized; thus, for positive - finite x, - 1 <= x x FLT_RADIX-logb(x) < FLT_RADIX - A domain error or pole error may occur if the argument is zero. - Returns -3 The logb functions return the signed exponent of x. - 7.12.6.12 The modf functions - Synopsis -1 #include - double modf(double value, double *iptr); - float modff(float value, float *iptr); - long double modfl(long double value, long double *iptr); - Description -2 The modf functions break the argument value into integral and fractional parts, each of - which has the same type and sign as the argument. They store the integral part (in -[page 244] - - floating-point format) in the object pointed to by iptr. - Returns -3 The modf functions return the signed fractional part of value. - 7.12.6.13 The scalbn and scalbln functions - Synopsis -1 #include - double scalbn(double x, int n); - float scalbnf(float x, int n); - long double scalbnl(long double x, int n); - double scalbln(double x, long int n); - float scalblnf(float x, long int n); - long double scalblnl(long double x, long int n); - Description -2 The scalbn and scalbln functions compute x x FLT_RADIXn efficiently, not - normally by computing FLT_RADIXn explicitly. A range error may occur. - Returns -3 The scalbn and scalbln functions return x x FLT_RADIXn . - 7.12.7 Power and absolute-value functions - 7.12.7.1 The cbrt functions - Synopsis -1 #include - double cbrt(double x); - float cbrtf(float x); - long double cbrtl(long double x); - Description -2 The cbrt functions compute the real cube root of x. - Returns -3 The cbrt functions return x1/3 . - - - - -[page 245] - - 7.12.7.2 The fabs functions - Synopsis -1 #include - double fabs(double x); - float fabsf(float x); - long double fabsl(long double x); - Description -2 The fabs functions compute the absolute value of a floating-point number x. - Returns -3 The fabs functions return | x |. - 7.12.7.3 The hypot functions - Synopsis -1 #include - double hypot(double x, double y); - float hypotf(float x, float y); - long double hypotl(long double x, long double y); - Description -2 The hypot functions compute the square root of the sum of the squares of x and y, - without undue overflow or underflow. A range error may occur. -3 Returns -4 The hypot functions return sqrt:x2 + y2 . - - - ----- - 7.12.7.4 The pow functions - Synopsis -1 #include - double pow(double x, double y); - float powf(float x, float y); - long double powl(long double x, long double y); - Description -2 The pow functions compute x raised to the power y. A domain error occurs if x is finite - and negative and y is finite and not an integer value. A range error may occur. A domain - error may occur if x is zero and y is zero. A domain error or pole error may occur if x is - zero and y is less than zero. - - - - -[page 246] - - Returns -3 The pow functions return xy . - 7.12.7.5 The sqrt functions - Synopsis -1 #include - double sqrt(double x); - float sqrtf(float x); - long double sqrtl(long double x); - Description -2 The sqrt functions compute the nonnegative square root of x. A domain error occurs if - the argument is less than zero. - Returns -3 The sqrt functions return sqrt:x. - - - - - 7.12.8 Error and gamma functions - 7.12.8.1 The erf functions - Synopsis -1 #include - double erf(double x); - float erff(float x); - long double erfl(long double x); - Description -2 The erf functions compute the error function of x. - Returns -3 2 x - (integral) e-t dt. - 2 - The erf functions return erf x = - sqrt:pi - - - - 0 - - 7.12.8.2 The erfc functions - Synopsis -1 #include - double erfc(double x); - float erfcf(float x); - long double erfcl(long double x); - Description -2 The erfc functions compute the complementary error function of x. A range error - occurs if x is too large. -[page 247] - - Returns -3 2 (inf) - (integral) e-t dt. - 2 - The erfc functions return erfc x = 1 - erf x = - sqrt:pi - - - - x - - 7.12.8.3 The lgamma functions - Synopsis -1 #include - double lgamma(double x); - float lgammaf(float x); - long double lgammal(long double x); - Description -2 The lgamma functions compute the natural logarithm of the absolute value of gamma of - x. A range error occurs if x is too large. A pole error may occur if x is a negative integer - or zero. - Returns -3 The lgamma functions return loge | (Gamma)(x) |. - 7.12.8.4 The tgamma functions - Synopsis -1 #include - double tgamma(double x); - float tgammaf(float x); - long double tgammal(long double x); - Description -2 The tgamma functions compute the gamma function of x. A domain error or pole error - may occur if x is a negative integer or zero. A range error occurs if the magnitude of x is - too large and may occur if the magnitude of x is too small. - Returns -3 The tgamma functions return (Gamma)(x). - - - - -[page 248] - - 7.12.9 Nearest integer functions - 7.12.9.1 The ceil functions - Synopsis -1 #include - double ceil(double x); - float ceilf(float x); - long double ceill(long double x); - Description -2 The ceil functions compute the smallest integer value not less than x. - Returns -3 The ceil functions return [^x^], expressed as a floating-point number. - 7.12.9.2 The floor functions - Synopsis -1 #include - double floor(double x); - float floorf(float x); - long double floorl(long double x); - Description -2 The floor functions compute the largest integer value not greater than x. - Returns -3 The floor functions return [_x_], expressed as a floating-point number. - 7.12.9.3 The nearbyint functions - Synopsis -1 #include - double nearbyint(double x); - float nearbyintf(float x); - long double nearbyintl(long double x); - Description -2 The nearbyint functions round their argument to an integer value in floating-point - format, using the current rounding direction and without raising the ''inexact'' floating- - point exception. - - - - -[page 249] - - Returns -3 The nearbyint functions return the rounded integer value. - 7.12.9.4 The rint functions - Synopsis -1 #include - double rint(double x); - float rintf(float x); - long double rintl(long double x); - Description -2 The rint functions differ from the nearbyint functions (7.12.9.3) only in that the - rint functions may raise the ''inexact'' floating-point exception if the result differs in - value from the argument. - Returns -3 The rint functions return the rounded integer value. - 7.12.9.5 The lrint and llrint functions - Synopsis -1 #include - long int lrint(double x); - long int lrintf(float x); - long int lrintl(long double x); - long long int llrint(double x); - long long int llrintf(float x); - long long int llrintl(long double x); - Description -2 The lrint and llrint functions round their argument to the nearest integer value, - rounding according to the current rounding direction. If the rounded value is outside the - range of the return type, the numeric result is unspecified and a domain error or range - error may occur. - Returns -3 The lrint and llrint functions return the rounded integer value. - - - - -[page 250] - - 7.12.9.6 The round functions - Synopsis -1 #include - double round(double x); - float roundf(float x); - long double roundl(long double x); - Description -2 The round functions round their argument to the nearest integer value in floating-point - format, rounding halfway cases away from zero, regardless of the current rounding - direction. - Returns -3 The round functions return the rounded integer value. - 7.12.9.7 The lround and llround functions - Synopsis -1 #include - long int lround(double x); - long int lroundf(float x); - long int lroundl(long double x); - long long int llround(double x); - long long int llroundf(float x); - long long int llroundl(long double x); - Description -2 The lround and llround functions round their argument to the nearest integer value, - rounding halfway cases away from zero, regardless of the current rounding direction. If - the rounded value is outside the range of the return type, the numeric result is unspecified - and a domain error or range error may occur. - Returns -3 The lround and llround functions return the rounded integer value. - 7.12.9.8 The trunc functions - Synopsis -1 #include - double trunc(double x); - float truncf(float x); - long double truncl(long double x); - - -[page 251] - - Description -2 The trunc functions round their argument to the integer value, in floating format, - nearest to but no larger in magnitude than the argument. - Returns -3 The trunc functions return the truncated integer value. - 7.12.10 Remainder functions - 7.12.10.1 The fmod functions - Synopsis -1 #include - double fmod(double x, double y); - float fmodf(float x, float y); - long double fmodl(long double x, long double y); - Description -2 The fmod functions compute the floating-point remainder of x/y. - Returns -3 The fmod functions return the value x - ny, for some integer n such that, if y is nonzero, - the result has the same sign as x and magnitude less than the magnitude of y. If y is zero, - whether a domain error occurs or the fmod functions return zero is implementation- - defined. - 7.12.10.2 The remainder functions - Synopsis -1 #include - double remainder(double x, double y); - float remainderf(float x, float y); - long double remainderl(long double x, long double y); - Description -2 The remainder functions compute the remainder x REM y required by IEC 60559.234) - - - - - 234) ''When y != 0, the remainder r = x REM y is defined regardless of the rounding mode by the - mathematical relation r = x - ny, where n is the integer nearest the exact value of x/y; whenever - | n - x/y | = 1/2, then n is even. If r = 0, its sign shall be that of x.'' This definition is applicable for - all implementations. - -[page 252] - - Returns -3 The remainder functions return x REM y. If y is zero, whether a domain error occurs - or the functions return zero is implementation defined. - 7.12.10.3 The remquo functions - Synopsis -1 #include - double remquo(double x, double y, int *quo); - float remquof(float x, float y, int *quo); - long double remquol(long double x, long double y, - int *quo); - Description -2 The remquo functions compute the same remainder as the remainder functions. In - the object pointed to by quo they store a value whose sign is the sign of x/y and whose - magnitude is congruent modulo 2n to the magnitude of the integral quotient of x/y, where - n is an implementation-defined integer greater than or equal to 3. - Returns -3 The remquo functions return x REM y. If y is zero, the value stored in the object - pointed to by quo is unspecified and whether a domain error occurs or the functions - return zero is implementation defined. - 7.12.11 Manipulation functions - 7.12.11.1 The copysign functions - Synopsis -1 #include - double copysign(double x, double y); - float copysignf(float x, float y); - long double copysignl(long double x, long double y); - Description -2 The copysign functions produce a value with the magnitude of x and the sign of y. - They produce a NaN (with the sign of y) if x is a NaN. On implementations that - represent a signed zero but do not treat negative zero consistently in arithmetic - operations, the copysign functions regard the sign of zero as positive. - Returns -3 The copysign functions return a value with the magnitude of x and the sign of y. - - - -[page 253] - - 7.12.11.2 The nan functions - Synopsis -1 #include - double nan(const char *tagp); - float nanf(const char *tagp); - long double nanl(const char *tagp); - Description -2 The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char- - sequence)", (char**) NULL); the call nan("") is equivalent to - strtod("NAN()", (char**) NULL). If tagp does not point to an n-char - sequence or an empty string, the call is equivalent to strtod("NAN", (char**) - NULL). Calls to nanf and nanl are equivalent to the corresponding calls to strtof - and strtold. - Returns -3 The nan functions return a quiet NaN, if available, with content indicated through tagp. - If the implementation does not support quiet NaNs, the functions return zero. - Forward references: the strtod, strtof, and strtold functions (7.22.1.3). - 7.12.11.3 The nextafter functions - Synopsis -1 #include - double nextafter(double x, double y); - float nextafterf(float x, float y); - long double nextafterl(long double x, long double y); - Description -2 The nextafter functions determine the next representable value, in the type of the - function, after x in the direction of y, where x and y are first converted to the type of the - function.235) The nextafter functions return y if x equals y. A range error may occur - if the magnitude of x is the largest finite value representable in the type and the result is - infinite or not representable in the type. - Returns -3 The nextafter functions return the next representable value in the specified format - after x in the direction of y. - - - 235) The argument values are converted to the type of the function, even by a macro implementation of the - function. - -[page 254] - - 7.12.11.4 The nexttoward functions - Synopsis -1 #include - double nexttoward(double x, long double y); - float nexttowardf(float x, long double y); - long double nexttowardl(long double x, long double y); - Description -2 The nexttoward functions are equivalent to the nextafter functions except that the - second parameter has type long double and the functions return y converted to the - type of the function if x equals y.236) - 7.12.12 Maximum, minimum, and positive difference functions - 7.12.12.1 The fdim functions - Synopsis -1 #include - double fdim(double x, double y); - float fdimf(float x, float y); - long double fdiml(long double x, long double y); - Description -2 The fdim functions determine the positive difference between their arguments: - {x - y if x > y - { - {+0 if x <= y - A range error may occur. - Returns -3 The fdim functions return the positive difference value. - 7.12.12.2 The fmax functions - Synopsis -1 #include - double fmax(double x, double y); - float fmaxf(float x, float y); - long double fmaxl(long double x, long double y); - - - - 236) The result of the nexttoward functions is determined in the type of the function, without loss of - range or precision in a floating second argument. - -[page 255] - - Description -2 The fmax functions determine the maximum numeric value of their arguments.237) - Returns -3 The fmax functions return the maximum numeric value of their arguments. - 7.12.12.3 The fmin functions - Synopsis -1 #include - double fmin(double x, double y); - float fminf(float x, float y); - long double fminl(long double x, long double y); - Description -2 The fmin functions determine the minimum numeric value of their arguments.238) - Returns -3 The fmin functions return the minimum numeric value of their arguments. - 7.12.13 Floating multiply-add - 7.12.13.1 The fma functions - Synopsis -1 #include - double fma(double x, double y, double z); - float fmaf(float x, float y, float z); - long double fmal(long double x, long double y, - long double z); - Description -2 The fma functions compute (x x y) + z, rounded as one ternary operation: they compute - the value (as if) to infinite precision and round once to the result format, according to the - current rounding mode. A range error may occur. - Returns -3 The fma functions return (x x y) + z, rounded as one ternary operation. - - - - - 237) NaN arguments are treated as missing data: if one argument is a NaN and the other numeric, then the - fmax functions choose the numeric value. See F.10.9.2. - 238) The fmin functions are analogous to the fmax functions in their treatment of NaNs. - -[page 256] - - 7.12.14 Comparison macros -1 The relational and equality operators support the usual mathematical relationships - between numeric values. For any ordered pair of numeric values exactly one of the - relationships -- less, greater, and equal -- is true. Relational operators may raise the - ''invalid'' floating-point exception when argument values are NaNs. For a NaN and a - numeric value, or for two NaNs, just the unordered relationship is true.239) The following - subclauses provide macros that are quiet (non floating-point exception raising) versions - of the relational operators, and other comparison macros that facilitate writing efficient - code that accounts for NaNs without suffering the ''invalid'' floating-point exception. In - the synopses in this subclause, real-floating indicates that the argument shall be an - expression of real floating type (both arguments need not have the same type).240) - 7.12.14.1 The isgreater macro - Synopsis -1 #include - int isgreater(real-floating x, real-floating y); - Description -2 The isgreater macro determines whether its first argument is greater than its second - argument. The value of isgreater(x, y) is always equal to (x) > (y); however, - unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point - exception when x and y are unordered. - Returns -3 The isgreater macro returns the value of (x) > (y). - 7.12.14.2 The isgreaterequal macro - Synopsis -1 #include - int isgreaterequal(real-floating x, real-floating y); - Description -2 The isgreaterequal macro determines whether its first argument is greater than or - equal to its second argument. The value of isgreaterequal(x, y) is always equal - to (x) >= (y); however, unlike (x) >= (y), isgreaterequal(x, y) does - - - 239) IEC 60559 requires that the built-in relational operators raise the ''invalid'' floating-point exception if - the operands compare unordered, as an error indicator for programs written without consideration of - NaNs; the result in these cases is false. - 240) Whether an argument represented in a format wider than its semantic type is converted to the semantic - type is unspecified. - -[page 257] - - not raise the ''invalid'' floating-point exception when x and y are unordered. - Returns -3 The isgreaterequal macro returns the value of (x) >= (y). - 7.12.14.3 The isless macro - Synopsis -1 #include - int isless(real-floating x, real-floating y); - Description -2 The isless macro determines whether its first argument is less than its second - argument. The value of isless(x, y) is always equal to (x) < (y); however, - unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point - exception when x and y are unordered. - Returns -3 The isless macro returns the value of (x) < (y). - 7.12.14.4 The islessequal macro - Synopsis -1 #include - int islessequal(real-floating x, real-floating y); - Description -2 The islessequal macro determines whether its first argument is less than or equal to - its second argument. The value of islessequal(x, y) is always equal to - (x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise - the ''invalid'' floating-point exception when x and y are unordered. - Returns -3 The islessequal macro returns the value of (x) <= (y). - 7.12.14.5 The islessgreater macro - Synopsis -1 #include - int islessgreater(real-floating x, real-floating y); - Description -2 The islessgreater macro determines whether its first argument is less than or - greater than its second argument. The islessgreater(x, y) macro is similar to - (x) < (y) || (x) > (y); however, islessgreater(x, y) does not raise - -[page 258] - - the ''invalid'' floating-point exception when x and y are unordered (nor does it evaluate x - and y twice). - Returns -3 The islessgreater macro returns the value of (x) < (y) || (x) > (y). - 7.12.14.6 The isunordered macro - Synopsis -1 #include - int isunordered(real-floating x, real-floating y); - Description -2 The isunordered macro determines whether its arguments are unordered. - Returns -3 The isunordered macro returns 1 if its arguments are unordered and 0 otherwise. - - - - -[page 259] - - 7.13 Nonlocal jumps -1 The header defines the macro setjmp, and declares one function and - one type, for bypassing the normal function call and return discipline.241) -2 The type declared is - jmp_buf - which is an array type suitable for holding the information needed to restore a calling - environment. The environment of a call to the setjmp macro consists of information - sufficient for a call to the longjmp function to return execution to the correct block and - invocation of that block, were it called recursively. It does not include the state of the - floating-point status flags, of open files, or of any other component of the abstract - machine. -3 It is unspecified whether setjmp is a macro or an identifier declared with external - linkage. If a macro definition is suppressed in order to access an actual function, or a - program defines an external identifier with the name setjmp, the behavior is undefined. - 7.13.1 Save calling environment - 7.13.1.1 The setjmp macro - Synopsis -1 #include - int setjmp(jmp_buf env); - Description -2 The setjmp macro saves its calling environment in its jmp_buf argument for later use - by the longjmp function. - Returns -3 If the return is from a direct invocation, the setjmp macro returns the value zero. If the - return is from a call to the longjmp function, the setjmp macro returns a nonzero - value. - Environmental limits -4 An invocation of the setjmp macro shall appear only in one of the following contexts: - -- the entire controlling expression of a selection or iteration statement; - -- one operand of a relational or equality operator with the other operand an integer - constant expression, with the resulting expression being the entire controlling - - - 241) These functions are useful for dealing with unusual conditions encountered in a low-level function of - a program. - -[page 260] - - expression of a selection or iteration statement; - -- the operand of a unary ! operator with the resulting expression being the entire - controlling expression of a selection or iteration statement; or - -- the entire expression of an expression statement (possibly cast to void). -5 If the invocation appears in any other context, the behavior is undefined. - 7.13.2 Restore calling environment - 7.13.2.1 The longjmp function - Synopsis -1 #include - _Noreturn void longjmp(jmp_buf env, int val); - Description -2 The longjmp function restores the environment saved by the most recent invocation of - the setjmp macro in the same invocation of the program with the corresponding - jmp_buf argument. If there has been no such invocation, or if the function containing - the invocation of the setjmp macro has terminated execution242) in the interim, or if the - invocation of the setjmp macro was within the scope of an identifier with variably - modified type and execution has left that scope in the interim, the behavior is undefined. -3 All accessible objects have values, and all other components of the abstract machine243) - have state, as of the time the longjmp function was called, except that the values of - objects of automatic storage duration that are local to the function containing the - invocation of the corresponding setjmp macro that do not have volatile-qualified type - and have been changed between the setjmp invocation and longjmp call are - indeterminate. - Returns -4 After longjmp is completed, program execution continues as if the corresponding - invocation of the setjmp macro had just returned the value specified by val. The - longjmp function cannot cause the setjmp macro to return the value 0; if val is 0, - the setjmp macro returns the value 1. -5 EXAMPLE The longjmp function that returns control back to the point of the setjmp invocation - might cause memory associated with a variable length array object to be squandered. - - - - - 242) For example, by executing a return statement or because another longjmp call has caused a - transfer to a setjmp invocation in a function earlier in the set of nested calls. - 243) This includes, but is not limited to, the floating-point status flags and the state of open files. - -[page 261] - - #include - jmp_buf buf; - void g(int n); - void h(int n); - int n = 6; - void f(void) - { - int x[n]; // valid: f is not terminated - setjmp(buf); - g(n); - } - void g(int n) - { - int a[n]; // a may remain allocated - h(n); - } - void h(int n) - { - int b[n]; // b may remain allocated - longjmp(buf, 2); // might cause memory loss - } - - - - -[page 262] - - 7.14 Signal handling -1 The header declares a type and two functions and defines several macros, - for handling various signals (conditions that may be reported during program execution). -2 The type defined is - sig_atomic_t - which is the (possibly volatile-qualified) integer type of an object that can be accessed as - an atomic entity, even in the presence of asynchronous interrupts. -3 The macros defined are - SIG_DFL - SIG_ERR - SIG_IGN - which expand to constant expressions with distinct values that have type compatible with - the second argument to, and the return value of, the signal function, and whose values - compare unequal to the address of any declarable function; and the following, which - expand to positive integer constant expressions with type int and distinct values that are - the signal numbers, each corresponding to the specified condition: - SIGABRT abnormal termination, such as is initiated by the abort function - SIGFPE an erroneous arithmetic operation, such as zero divide or an operation - resulting in overflow - SIGILL detection of an invalid function image, such as an invalid instruction - SIGINT receipt of an interactive attention signal - SIGSEGV an invalid access to storage - SIGTERM a termination request sent to the program -4 An implementation need not generate any of these signals, except as a result of explicit - calls to the raise function. Additional signals and pointers to undeclarable functions, - with macro definitions beginning, respectively, with the letters SIG and an uppercase - letter or with SIG_ and an uppercase letter,244) may also be specified by the - implementation. The complete set of signals, their semantics, and their default handling - is implementation-defined; all signal numbers shall be positive. - - - - - 244) See ''future library directions'' (7.30.6). The names of the signal numbers reflect the following terms - (respectively): abort, floating-point exception, illegal instruction, interrupt, segmentation violation, - and termination. - -[page 263] - - 7.14.1 Specify signal handling - 7.14.1.1 The signal function - Synopsis -1 #include - void (*signal(int sig, void (*func)(int)))(int); - Description -2 The signal function chooses one of three ways in which receipt of the signal number - sig is to be subsequently handled. If the value of func is SIG_DFL, default handling - for that signal will occur. If the value of func is SIG_IGN, the signal will be ignored. - Otherwise, func shall point to a function to be called when that signal occurs. An - invocation of such a function because of a signal, or (recursively) of any further functions - called by that invocation (other than functions in the standard library), is called a signal - handler. -3 When a signal occurs and func points to a function, it is implementation-defined - whether the equivalent of signal(sig, SIG_DFL); is executed or the - implementation prevents some implementation-defined set of signals (at least including - sig) from occurring until the current signal handling has completed; in the case of - SIGILL, the implementation may alternatively define that no action is taken. Then the - equivalent of (*func)(sig); is executed. If and when the function returns, if the - value of sig is SIGFPE, SIGILL, SIGSEGV, or any other implementation-defined - value corresponding to a computational exception, the behavior is undefined; otherwise - the program will resume execution at the point it was interrupted. -4 If the signal occurs as the result of calling the abort or raise function, the signal - handler shall not call the raise function. -5 If the signal occurs other than as the result of calling the abort or raise function, the - behavior is undefined if the signal handler refers to any object with static or thread - storage duration other than by assigning a value to an object declared as volatile - sig_atomic_t, or the signal handler calls any function in the standard library other - than the abort function, the _Exit function, the quick_exit function, or the - signal function with the first argument equal to the signal number corresponding to the - signal that caused the invocation of the handler. Furthermore, if such a call to the - signal function results in a SIG_ERR return, the value of errno is indeterminate.245) -6 At program startup, the equivalent of - signal(sig, SIG_IGN); - - - 245) If any signal is generated by an asynchronous signal handler, the behavior is undefined. - -[page 264] - - may be executed for some signals selected in an implementation-defined manner; the - equivalent of - signal(sig, SIG_DFL); - is executed for all other signals defined by the implementation. -7 The implementation shall behave as if no library function calls the signal function. - Returns -8 If the request can be honored, the signal function returns the value of func for the - most recent successful call to signal for the specified signal sig. Otherwise, a value of - SIG_ERR is returned and a positive value is stored in errno. - Forward references: the abort function (7.22.4.1), the exit function (7.22.4.4), the - _Exit function (7.22.4.5), the quick_exit function (7.22.4.7). - 7.14.2 Send signal - 7.14.2.1 The raise function - Synopsis -1 #include - int raise(int sig); - Description -2 The raise function carries out the actions described in 7.14.1.1 for the signal sig. If a - signal handler is called, the raise function shall not return until after the signal handler - does. - Returns -3 The raise function returns zero if successful, nonzero if unsuccessful. - - - - -[page 265] - - 7.15 Alignment -1 The header defines two macros. -2 The macro - alignas - expands to _Alignas. -3 The remaining macro is suitable for use in #if preprocessing directives. It is - __alignas_is_defined - which expands to the integer constant 1. - - - - -[page 266] - - 7.16 Variable arguments -1 The header declares a type and defines four macros, for advancing - through a list of arguments whose number and types are not known to the called function - when it is translated. -2 A function may be called with a variable number of arguments of varying types. As - described in 6.9.1, its parameter list contains one or more parameters. The rightmost - parameter plays a special role in the access mechanism, and will be designated parmN in - this description. -3 The type declared is - va_list - which is a complete object type suitable for holding information needed by the macros - va_start, va_arg, va_end, and va_copy. If access to the varying arguments is - desired, the called function shall declare an object (generally referred to as ap in this - subclause) having type va_list. The object ap may be passed as an argument to - another function; if that function invokes the va_arg macro with parameter ap, the - value of ap in the calling function is indeterminate and shall be passed to the va_end - macro prior to any further reference to ap.246) - 7.16.1 Variable argument list access macros -1 The va_start and va_arg macros described in this subclause shall be implemented - as macros, not functions. It is unspecified whether va_copy and va_end are macros or - identifiers declared with external linkage. If a macro definition is suppressed in order to - access an actual function, or a program defines an external identifier with the same name, - the behavior is undefined. Each invocation of the va_start and va_copy macros - shall be matched by a corresponding invocation of the va_end macro in the same - function. - 7.16.1.1 The va_arg macro - Synopsis -1 #include - type va_arg(va_list ap, type); - Description -2 The va_arg macro expands to an expression that has the specified type and the value of - the next argument in the call. The parameter ap shall have been initialized by the - va_start or va_copy macro (without an intervening invocation of the va_end - - 246) It is permitted to create a pointer to a va_list and pass that pointer to another function, in which - case the original function may make further use of the original list after the other function returns. - -[page 267] - - macro for the same ap). Each invocation of the va_arg macro modifies ap so that the - values of successive arguments are returned in turn. The parameter type shall be a type - name specified such that the type of a pointer to an object that has the specified type can - be obtained simply by postfixing a * to type. If there is no actual next argument, or if - type is not compatible with the type of the actual next argument (as promoted according - to the default argument promotions), the behavior is undefined, except for the following - cases: - -- one type is a signed integer type, the other type is the corresponding unsigned integer - type, and the value is representable in both types; - -- one type is pointer to void and the other is a pointer to a character type. - Returns -3 The first invocation of the va_arg macro after that of the va_start macro returns the - value of the argument after that specified by parmN . Successive invocations return the - values of the remaining arguments in succession. - 7.16.1.2 The va_copy macro - Synopsis -1 #include - void va_copy(va_list dest, va_list src); - Description -2 The va_copy macro initializes dest as a copy of src, as if the va_start macro had - been applied to dest followed by the same sequence of uses of the va_arg macro as - had previously been used to reach the present state of src. Neither the va_copy nor - va_start macro shall be invoked to reinitialize dest without an intervening - invocation of the va_end macro for the same dest. - Returns -3 The va_copy macro returns no value. - 7.16.1.3 The va_end macro - Synopsis -1 #include - void va_end(va_list ap); - Description -2 The va_end macro facilitates a normal return from the function whose variable - argument list was referred to by the expansion of the va_start macro, or the function - containing the expansion of the va_copy macro, that initialized the va_list ap. The - va_end macro may modify ap so that it is no longer usable (without being reinitialized - -[page 268] - - by the va_start or va_copy macro). If there is no corresponding invocation of the - va_start or va_copy macro, or if the va_end macro is not invoked before the - return, the behavior is undefined. - Returns -3 The va_end macro returns no value. - 7.16.1.4 The va_start macro - Synopsis -1 #include - void va_start(va_list ap, parmN); - Description -2 The va_start macro shall be invoked before any access to the unnamed arguments. -3 The va_start macro initializes ap for subsequent use by the va_arg and va_end - macros. Neither the va_start nor va_copy macro shall be invoked to reinitialize ap - without an intervening invocation of the va_end macro for the same ap. -4 The parameter parmN is the identifier of the rightmost parameter in the variable - parameter list in the function definition (the one just before the , ...). If the parameter - parmN is declared with the register storage class, with a function or array type, or - with a type that is not compatible with the type that results after application of the default - argument promotions, the behavior is undefined. - Returns -5 The va_start macro returns no value. -6 EXAMPLE 1 The function f1 gathers into an array a list of arguments that are pointers to strings (but not - more than MAXARGS arguments), then passes the array as a single argument to function f2. The number of - pointers is specified by the first argument to f1. - #include - #define MAXARGS 31 - void f1(int n_ptrs, ...) - { - va_list ap; - char *array[MAXARGS]; - int ptr_no = 0; - - - - -[page 269] - - if (n_ptrs > MAXARGS) - n_ptrs = MAXARGS; - va_start(ap, n_ptrs); - while (ptr_no < n_ptrs) - array[ptr_no++] = va_arg(ap, char *); - va_end(ap); - f2(n_ptrs, array); - } - Each call to f1 is required to have visible the definition of the function or a declaration such as - void f1(int, ...); - -7 EXAMPLE 2 The function f3 is similar, but saves the status of the variable argument list after the - indicated number of arguments; after f2 has been called once with the whole list, the trailing part of the list - is gathered again and passed to function f4. - #include - #define MAXARGS 31 - void f3(int n_ptrs, int f4_after, ...) - { - va_list ap, ap_save; - char *array[MAXARGS]; - int ptr_no = 0; - if (n_ptrs > MAXARGS) - n_ptrs = MAXARGS; - va_start(ap, f4_after); - while (ptr_no < n_ptrs) { - array[ptr_no++] = va_arg(ap, char *); - if (ptr_no == f4_after) - va_copy(ap_save, ap); - } - va_end(ap); - f2(n_ptrs, array); - // Now process the saved copy. - n_ptrs -= f4_after; - ptr_no = 0; - while (ptr_no < n_ptrs) - array[ptr_no++] = va_arg(ap_save, char *); - va_end(ap_save); - f4(n_ptrs, array); - } - - - - -[page 270] - - 7.17 Atomics - 7.17.1 Introduction -1 The header defines several macros and declares several types and - functions for performing atomic operations on data shared between threads. -2 Implementations that define the macro __STDC_NO_THREADS__ need not provide - this header nor support any of its facilities. -3 The macros defined are the atomic lock-free macros - ATOMIC_CHAR_LOCK_FREE - ATOMIC_CHAR16_T_LOCK_FREE - ATOMIC_CHAR32_T_LOCK_FREE - ATOMIC_WCHAR_T_LOCK_FREE - ATOMIC_SHORT_LOCK_FREE - ATOMIC_INT_LOCK_FREE - ATOMIC_LONG_LOCK_FREE - ATOMIC_LLONG_LOCK_FREE - ATOMIC_ADDRESS_LOCK_FREE - which indicate the lock-free property of the corresponding atomic types (both signed and - unsigned); and - ATOMIC_FLAG_INIT - which expands to an initializer for an object of type atomic_flag. -4 The types include - memory_order - which is an enumerated type whose enumerators identify memory ordering constraints; - atomic_flag - which is a structure type representing a lock-free, primitive atomic flag; - atomic_bool - which is a structure type representing the atomic analog of the type _Bool; - atomic_address - which is a structure type representing the atomic analog of a pointer type; and several - atomic analogs of integer types. -5 In the following operation definitions: - -- An A refers to one of the atomic types. - - -[page 271] - - -- A C refers to its corresponding non-atomic type. The atomic_address atomic - type corresponds to the void * non-atomic type. - -- An M refers to the type of the other argument for arithmetic operations. For atomic - integer types, M is C. For atomic address types, M is ptrdiff_t. - -- The functions not ending in _explicit have the same semantics as the - corresponding _explicit function with memory_order_seq_cst for the - memory_order argument. - 6 NOTE Many operations are volatile-qualified. The ''volatile as device register'' semantics have not - changed in the standard. This qualification means that volatility is preserved when applying these - operations to volatile objects. - - 7.17.2 Initialization - 7.17.2.1 The ATOMIC_VAR_INIT macro - Synopsis -1 #include - #define ATOMIC_VAR_INIT(C value) - Description -2 The ATOMIC_VAR_INIT macro expands to a token sequence suitable for initializing an - atomic object of a type that is initialization-compatible with value. An atomic object - with automatic storage duration that is not explicitly initialized using - ATOMIC_VAR_INIT is initially in an indeterminate state; however, the default (zero) - initialization for objects with static or thread-local storage duration is guaranteed to - produce a valid state. -3 Concurrent access to the variable being initialized, even via an atomic operation, - constitutes a data race. -4 EXAMPLE - atomic_int guide = ATOMIC_VAR_INIT(42); - - 7.17.2.2 The atomic_init generic function - Synopsis -1 #include - void atomic_init(volatile A *obj, C value); - Description -2 The atomic_init generic function initializes the atomic object pointed to by obj to - the value value, while also initializing any additional state that the implementation - might need to carry for the atomic object. - - - -[page 272] - -3 Although this function initializes an atomic object, it does not avoid data races; - concurrent access to the variable being initialized, even via an atomic operation, - constitutes a data race. - Returns -4 The atomic_init generic function returns no value. -5 EXAMPLE - atomic_int guide; - atomic_init(&guide, 42); - - 7.17.3 Order and consistency -1 The enumerated type memory_order specifies the detailed regular (non-atomic) - memory synchronization operations as defined in 5.1.2.4 and may provide for operation - ordering. Its enumeration constants are as follows: - memory_order_relaxed - memory_order_consume - memory_order_acquire - memory_order_release - memory_order_acq_rel - memory_order_seq_cst -2 For memory_order_relaxed, no operation orders memory. -3 For memory_order_release, memory_order_acq_rel, and - memory_order_seq_cst, a store operation performs a release operation on the - affected memory location. -4 For memory_order_acquire, memory_order_acq_rel, and - memory_order_seq_cst, a load operation performs an acquire operation on the - affected memory location. -5 For memory_order_consume, a load operation performs a consume operation on the - affected memory location. -6 For memory_order_seq_cst, there shall be a single total order S on all operations, - consistent with the ''happens before'' order and modification orders for all affected - locations, such that each memory_order_seq_cst operation that loads a value - observes either the last preceding modification according to this order S, or the result of - an operation that is not memory_order_seq_cst. -7 NOTE 1 Although it is not explicitly required that S include lock operations, it can always be extended to - an order that does include lock and unlock operations, since the ordering between those is already included - in the ''happens before'' ordering. - -8 NOTE 2 Atomic operations specifying memory_order_relaxed are relaxed only with respect to - memory ordering. Implementations must still guarantee that any given atomic access to a particular atomic - -[page 273] - - object be indivisible with respect to all other atomic accesses to that object. - -9 For an atomic operation B that reads the value of an atomic object M, if there is a - memory_order_seq_cst fence X sequenced before B, then B observes either the - last memory_order_seq_cst modification of M preceding X in the total order S or - a later modification of M in its modification order. -10 For atomic operations A and B on an atomic object M, where A modifies M and B takes - its value, if there is a memory_order_seq_cst fence X such that A is sequenced - before X and B follows X in S, then B observes either the effects of A or a later - modification of M in its modification order. -11 For atomic operations A and B on an atomic object M, where A modifies M and B takes - its value, if there are memory_order_seq_cst fences X and Y such that A is - sequenced before X, Y is sequenced before B, and X precedes Y in S, then B observes - either the effects of A or a later modification of M in its modification order. -12 Atomic read-modify-write operations shall always read the last value (in the modification - order) stored before the write associated with the read-modify-write operation. -13 An atomic store shall only store a value that has been computed from constants and - program input values by a finite sequence of program evaluations, such that each - evaluation observes the values of variables as computed by the last prior assignment in - the sequence.247) The ordering of evaluations in this sequence shall be such that - -- If an evaluation B observes a value computed by A in a different thread, then B does - not happen before A. - -- If an evaluation A is included in the sequence, then all evaluations that assign to the - same variable and happen before A are also included. -14 NOTE 3 The second requirement disallows ''out-of-thin-air'', or ''speculative'' stores of atomics when - relaxed atomics are used. Since unordered operations are involved, evaluations may appear in this - sequence out of thread order. For example, with x and y initially zero, - // Thread 1: - r1 = atomic_load_explicit(&y, memory_order_relaxed); - atomic_store_explicit(&x, r1, memory_order_relaxed); - - // Thread 2: - r2 = atomic_load_explicit(&x, memory_order_relaxed); - atomic_store_explicit(&y, 42, memory_order_relaxed); - is allowed to produce r1 == 42 && r2 == 42. The sequence of evaluations justifying this consists of: - - - - - 247) Among other implications, atomic variables shall not decay. - -[page 274] - - atomic_store_explicit(&y, 42, memory_order_relaxed); - r1 = atomic_load_explicit(&y, memory_order_relaxed); - atomic_store_explicit(&x, r1, memory_order_relaxed); - r2 = atomic_load_explicit(&x, memory_order_relaxed); - On the other hand, - // Thread 1: - r1 = atomic_load_explicit(&y, memory_order_relaxed); - atomic_store_explicit(&x, r1, memory_order_relaxed); - - // Thread 2: - r2 = atomic_load_explicit(&x, memory_order_relaxed); - atomic_store_explicit(&y, r2, memory_order_relaxed); - is not allowed to produce r1 == 42 && r2 = 42, since there is no sequence of evaluations that results - in the computation of 42. In the absence of ''relaxed'' operations and read-modify-write operations with - weaker than memory_order_acq_rel ordering, the second requirement has no impact. - - Recommended practice -15 The requirements do not forbid r1 == 42 && r2 == 42 in the following example, - with x and y initially zero: - // Thread 1: - r1 = atomic_load_explicit(&x, memory_order_relaxed); - if (r1 == 42) - atomic_store_explicit(&y, r1, memory_order_relaxed); - - // Thread 2: - r2 = atomic_load_explicit(&y, memory_order_relaxed); - if (r2 == 42) - atomic_store_explicit(&x, 42, memory_order_relaxed); - However, this is not useful behavior, and implementations should not allow it. -16 Implementations should make atomic stores visible to atomic loads within a reasonable - amount of time. - 7.17.3.1 The kill_dependency macro - Synopsis -1 #include - type kill_dependency(type y); - Description -2 The kill_dependency macro terminates a dependency chain; the argument does not - carry a dependency to the return value. - - - -[page 275] - - Returns -3 The kill_dependency macro returns the value of y. - 7.17.4 Fences -1 This subclause introduces synchronization primitives called fences. Fences can have - acquire semantics, release semantics, or both. A fence with acquire semantics is called - an acquire fence; a fence with release semantics is called a release fence. -2 A release fence A synchronizes with an acquire fence B if there exist atomic operations - X and Y , both operating on some atomic object M, such that A is sequenced before X, X - modifies M, Y is sequenced before B, and Y reads the value written by X or a value - written by any side effect in the hypothetical release sequence X would head if it were a - release operation. -3 A release fence A synchronizes with an atomic operation B that performs an acquire - operation on an atomic object M if there exists an atomic operation X such that A is - sequenced before X, X modifies M, and B reads the value written by X or a value written - by any side effect in the hypothetical release sequence X would head if it were a release - operation. -4 An atomic operation A that is a release operation on an atomic object M synchronizes - with an acquire fence B if there exists some atomic operation X on M such that X is - sequenced before B and reads the value written by A or a value written by any side effect - in the release sequence headed by A. - 7.17.4.1 The atomic_thread_fence function - Synopsis -1 #include - void atomic_thread_fence(memory_order order); - Description -2 Depending on the value of order, this operation: - -- has no effects, if order == memory_order_relaxed; - -- is an acquire fence, if order == memory_order_acquire or order == - memory_order_consume; - -- is a release fence, if order == memory_order_release; - -- is both an acquire fence and a release fence, if order == - memory_order_acq_rel; - -- is a sequentially consistent acquire and release fence, if order == - memory_order_seq_cst. - - -[page 276] - - Returns -3 The atomic_thread_fence function returns no value. - 7.17.4.2 The atomic_signal_fence function - Synopsis -1 #include - void atomic_signal_fence(memory_order order); - Description -2 Equivalent to atomic_thread_fence(order), except that ''synchronizes with'' - relationships are established only between a thread and a signal handler executed in the - same thread. -3 NOTE 1 The atomic_signal_fence function can be used to specify the order in which actions - performed by the thread become visible to the signal handler. - -4 NOTE 2 Compiler optimizations and reorderings of loads and stores are inhibited in the same way as with - atomic_thread_fence, but the hardware fence instructions that atomic_thread_fence would - have inserted are not emitted. - - Returns -5 The atomic_signal_fence function returns no value. - 7.17.5 Lock-free property -1 The atomic lock-free macros indicate the lock-free property of integer and address atomic - types. A value of 0 indicates that the type is never lock-free; a value of 1 indicates that - the type is sometimes lock-free; a value of 2 indicates that the type is always lock-free. -2 NOTE Operations that are lock-free should also be address-free. That is, atomic operations on the same - memory location via two different addresses will communicate atomically. The implementation should not - depend on any per-process state. This restriction enables communication via memory mapped into a - process more than once and memory shared between two processes. - - 7.17.5.1 The atomic_is_lock_free generic function - Synopsis -1 #include - _Bool atomic_is_lock_free(atomic_type const volatile *obj); - Description -2 The atomic_is_lock_free generic function indicates whether or not the object - pointed to by obj is lock-free. atomic_type can be any atomic type. - Returns -3 The atomic_is_lock_free generic function returns nonzero (true) if and only if the - object's operations are lock-free. The result of a lock-free query on one object cannot be - -[page 277] - - inferred from the result of a lock-free query on another object. - 7.17.6 Atomic integer and address types -1 For each line in the following table, the atomic type name is declared as the - corresponding direct type. - - - - -[page 278] - - - - Atomic type name Direct type - atomic_char _Atomic char - atomic_schar _Atomic signed char - atomic_uchar _Atomic unsigned char - atomic_short _Atomic short - atomic_ushort _Atomic unsigned short - atomic_int _Atomic int - atomic_uint _Atomic unsigned int - atomic_long _Atomic long - atomic_ulong _Atomic unsigned long - atomic_llong _Atomic long long - atomic_ullong _Atomic unsigned long long - atomic_char16_t _Atomic char16_t - atomic_char32_t _Atomic char32_t - atomic_wchar_t _Atomic wchar_t - atomic_int_least8_t _Atomic int_least8_t - atomic_uint_least8_t _Atomic uint_least8_t - atomic_int_least16_t _Atomic int_least16_t - atomic_uint_least16_t _Atomic uint_least16_t - atomic_int_least32_t _Atomic int_least32_t - atomic_uint_least32_t _Atomic uint_least32_t - atomic_int_least64_t _Atomic int_least64_t - atomic_uint_least64_t _Atomic uint_least64_t - atomic_int_fast8_t _Atomic int_fast8_t - atomic_uint_fast8_t _Atomic uint_fast8_t - atomic_int_fast16_t _Atomic int_fast16_t - atomic_uint_fast16_t _Atomic uint_fast16_t - atomic_int_fast32_t _Atomic int_fast32_t - atomic_uint_fast32_t _Atomic uint_fast32_t - atomic_int_fast64_t _Atomic int_fast64_t - atomic_uint_fast64_t _Atomic uint_fast64_t - atomic_intptr_t _Atomic intptr_t - atomic_uintptr_t _Atomic uintptr_t - atomic_size_t _Atomic size_t - atomic_ptrdiff_t _Atomic ptrdiff_t - atomic_intmax_t _Atomic intmax_t - atomic_uintmax_t _Atomic uintmax_t -2 The semantics of the operations on these types are defined in 7.17.7. - - - -[page 279] - -3 The atomic_bool type provides an atomic boolean. -4 The atomic_address type provides atomic void * operations. The unit of - addition/subtraction shall be one byte. -5 NOTE The representation of atomic integer and address types need not have the same size as their - corresponding regular types. They should have the same size whenever possible, as it eases effort required - to port existing code. - - 7.17.7 Operations on atomic types -1 There are only a few kinds of operations on atomic types, though there are many - instances of those kinds. This subclause specifies each general kind. - 7.17.7.1 The atomic_store generic functions - Synopsis -1 #include - void atomic_store(volatile A *object, C desired); - void atomic_store_explicit(volatile A *object, - C desired, memory_order order); - Description -2 The order argument shall not be memory_order_acquire, - memory_order_consume, nor memory_order_acq_rel. Atomically replace the - value pointed to by object with the value of desired. Memory is affected according - to the value of order. - Returns -3 The atomic_store generic functions return no value. - 7.17.7.2 The atomic_load generic functions - Synopsis -1 #include - C atomic_load(volatile A *object); - C atomic_load_explicit(volatile A *object, - memory_order order); - Description -2 The order argument shall not be memory_order_release nor - memory_order_acq_rel. Memory is affected according to the value of order. - Returns - Atomically returns the value pointed to by object. - - - -[page 280] - - 7.17.7.3 The atomic_exchange generic functions - Synopsis -1 #include - C atomic_exchange(volatile A *object, C desired); - C atomic_exchange_explicit(volatile A *object, - C desired, memory_order order); - Description -2 Atomically replace the value pointed to by object with desired. Memory is affected - according to the value of order. These operations are read-modify-write operations - (5.1.2.4). - Returns -3 Atomically returns the value pointed to by object immediately before the effects. - 7.17.7.4 The atomic_compare_exchange generic functions - Synopsis -1 #include - _Bool atomic_compare_exchange_strong(volatile A *object, - C *expected, C desired); - _Bool atomic_compare_exchange_strong_explicit( - volatile A *object, C *expected, C desired, - memory_order success, memory_order failure); - _Bool atomic_compare_exchange_weak(volatile A *object, - C *expected, C desired); - _Bool atomic_compare_exchange_weak_explicit( - volatile A *object, C *expected, C desired, - memory_order success, memory_order failure); - Description -2 The failure argument shall not be memory_order_release nor - memory_order_acq_rel. The failure argument shall be no stronger than the - success argument. Atomically, compares the value pointed to by object for equality - with that in expected, and if true, replaces the value pointed to by object with - desired, and if false, updates the value in expected with the value pointed to by - object. Further, if the comparison is true, memory is affected according to the value of - success, and if the comparison is false, memory is affected according to the value of - failure. These operations are atomic read-modify-write operations (5.1.2.4). -3 NOTE 1 The effect of the compare-and-exchange operations is - - - - -[page 281] - - if (*object == *expected) - *object = desired; - else - *expected = *object; - -4 The weak compare-and-exchange operations may fail spuriously, that is, return zero - while leaving the value pointed to by expected unchanged. -5 NOTE 2 This spurious failure enables implementation of compare-and-exchange on a broader class of - machines, e.g. load-locked store-conditional machines. - -6 EXAMPLE A consequence of spurious failure is that nearly all uses of weak compare-and-exchange will - be in a loop. - exp = atomic_load(&cur); - do { - des = function(exp); - } while (!atomic_compare_exchange_weak(&cur, &exp, des)); - When a compare-and-exchange is in a loop, the weak version will yield better performance on some - platforms. When a weak compare-and-exchange would require a loop and a strong one would not, the - strong one is preferable. - - Returns -7 The result of the comparison. - 7.17.7.5 The atomic_fetch and modify generic functions -1 The following operations perform arithmetic and bitwise computations. All of these - operations are applicable to an object of any atomic integer type. Only addition and - subtraction are applicable to atomic_address. None of these operations is applicable - to atomic_bool. The key, operator, and computation correspondence is: - - - key op computation - add + addition - sub - subtraction - or | bitwise inclusive or - xor ^ bitwise exclusive or - and & bitwise and - Synopsis -2 #include - C atomic_fetch_key(volatile A *object, M operand); - C atomic_fetch_key_explicit(volatile A *object, - M operand, memory_order order); - Description -3 Atomically replaces the value pointed to by object with the result of the computation - applied to the value pointed to by object and the given operand. Memory is affected -[page 282] - - according to the value of order. These operations are atomic read-modify-write - operations (5.1.2.4). For signed integer types, arithmetic is defined to use two's- - complement representation. There are no undefined results. For address types, the result - may be an undefined address, but the operations otherwise have no undefined behavior. - Returns -4 Atomically, the value pointed to by object immediately before the effects. -5 NOTE The operation of the atomic_fetch and modify generic functions are nearly equivalent to the - operation of the corresponding op= compound assignment operators. The only differences are that the - compound assignment operators are not guaranteed to operate atomically, and the value yielded by a - compound assignment operator is the updated value of the object, whereas the value returned by the - atomic_fetch and modify generic functions is the previous value of the atomic object. - - 7.17.8 Atomic flag type and operations -1 The atomic_flag type provides the classic test-and-set functionality. It has two - states, set and clear. -2 Operations on an object of type atomic_flag shall be lock free. -3 NOTE Hence the operations should also be address-free. No other type requires lock-free operations, so - the atomic_flag type is the minimum hardware-implemented type needed to conform to this - International standard. The remaining types can be emulated with atomic_flag, though with less than - ideal properties. - -4 The macro ATOMIC_FLAG_INIT may be used to initialize an atomic_flag to the - clear state. An atomic_flag that is not explicitly initialized with - ATOMIC_FLAG_INIT is initially in an indeterminate state. -5 EXAMPLE - atomic_flag guard = ATOMIC_FLAG_INIT; - - 7.17.8.1 The atomic_flag_test_and_set functions - Synopsis -1 #include - bool atomic_flag_test_and_set( - volatile atomic_flag *object); - bool atomic_flag_test_and_set_explicit( - volatile atomic_flag *object, memory_order order); - Description -2 Atomically sets the value pointed to by object to true. Memory is affected according - to the value of order. These operations are atomic read-modify-write operations - (5.1.2.4). - - - - -[page 283] - - Returns -3 Atomically, the value of the object immediately before the effects. - 7.17.8.2 The atomic_flag_clear functions - Synopsis -1 #include - void atomic_flag_clear(volatile atomic_flag *object); - void atomic_flag_clear_explicit( - volatile atomic_flag *object, memory_order order); - Description -2 The order argument shall not be memory_order_acquire nor - memory_order_acq_rel. Atomically sets the value pointed to by object to false. - Memory is affected according to the value of order. - Returns -3 The atomic_flag_clear functions return no value. - - - - -[page 284] - - 7.18 Boolean type and values -1 The header defines four macros. -2 The macro - bool - expands to _Bool. -3 The remaining three macros are suitable for use in #if preprocessing directives. They - are - true - which expands to the integer constant 1, - false - which expands to the integer constant 0, and - __bool_true_false_are_defined - which expands to the integer constant 1. -4 Notwithstanding the provisions of 7.1.3, a program may undefine and perhaps then - redefine the macros bool, true, and false.248) - - - - - 248) See ''future library directions'' (7.30.7). - -[page 285] - - 7.19 Common definitions -1 The header defines the following macros and declares the following types. - Some are also defined in other headers, as noted in their respective subclauses. -2 The types are - ptrdiff_t - which is the signed integer type of the result of subtracting two pointers; - size_t - which is the unsigned integer type of the result of the sizeof operator; - max_align_t - which is an object type whose alignment is as great as is supported by the implementation - in all contexts; and - wchar_t - which is an integer type whose range of values can represent distinct codes for all - members of the largest extended character set specified among the supported locales; the - null character shall have the code value zero. Each member of the basic character set - shall have a code value equal to its value when used as the lone character in an integer - character constant if an implementation does not define - __STDC_MB_MIGHT_NEQ_WC__. -3 The macros are - NULL - which expands to an implementation-defined null pointer constant; and - offsetof(type, member-designator) - which expands to an integer constant expression that has type size_t, the value of - which is the offset in bytes, to the structure member (designated by member-designator), - from the beginning of its structure (designated by type). The type and member designator - shall be such that given - static type t; - then the expression &(t.member-designator) evaluates to an address constant. (If the - specified member is a bit-field, the behavior is undefined.) - Recommended practice -4 The types used for size_t and ptrdiff_t should not have an integer conversion rank - greater than that of signed long int unless the implementation supports objects - large enough to make this necessary. - -[page 286] - -Forward references: localization (7.11). - - - - -[page 287] - - 7.20 Integer types -1 The header declares sets of integer types having specified widths, and - defines corresponding sets of macros.249) It also defines macros that specify limits of - integer types corresponding to types defined in other standard headers. -2 Types are defined in the following categories: - -- integer types having certain exact widths; - -- integer types having at least certain specified widths; - -- fastest integer types having at least certain specified widths; - -- integer types wide enough to hold pointers to objects; - -- integer types having greatest width. - (Some of these types may denote the same type.) -3 Corresponding macros specify limits of the declared types and construct suitable - constants. -4 For each type described herein that the implementation provides,250) shall - declare that typedef name and define the associated macros. Conversely, for each type - described herein that the implementation does not provide, shall not - declare that typedef name nor shall it define the associated macros. An implementation - shall provide those types described as ''required'', but need not provide any of the others - (described as ''optional''). - 7.20.1 Integer types -1 When typedef names differing only in the absence or presence of the initial u are defined, - they shall denote corresponding signed and unsigned types as described in 6.2.5; an - implementation providing one of these corresponding types shall also provide the other. -2 In the following descriptions, the symbol N represents an unsigned decimal integer with - no leading zeros (e.g., 8 or 24, but not 04 or 048). - - - - - 249) See ''future library directions'' (7.30.8). - 250) Some of these types may denote implementation-defined extended integer types. - -[page 288] - - 7.20.1.1 Exact-width integer types -1 The typedef name intN_t designates a signed integer type with width N , no padding - bits, and a two's complement representation. Thus, int8_t denotes such a signed - integer type with a width of exactly 8 bits. -2 The typedef name uintN_t designates an unsigned integer type with width N and no - padding bits. Thus, uint24_t denotes such an unsigned integer type with a width of - exactly 24 bits. -3 These types are optional. However, if an implementation provides integer types with - widths of 8, 16, 32, or 64 bits, no padding bits, and (for the signed types) that have a - two's complement representation, it shall define the corresponding typedef names. - 7.20.1.2 Minimum-width integer types -1 The typedef name int_leastN_t designates a signed integer type with a width of at - least N , such that no signed integer type with lesser size has at least the specified width. - Thus, int_least32_t denotes a signed integer type with a width of at least 32 bits. -2 The typedef name uint_leastN_t designates an unsigned integer type with a width - of at least N , such that no unsigned integer type with lesser size has at least the specified - width. Thus, uint_least16_t denotes an unsigned integer type with a width of at - least 16 bits. -3 The following types are required: - int_least8_t uint_least8_t - int_least16_t uint_least16_t - int_least32_t uint_least32_t - int_least64_t uint_least64_t - All other types of this form are optional. - 7.20.1.3 Fastest minimum-width integer types -1 Each of the following types designates an integer type that is usually fastest251) to operate - with among all integer types that have at least the specified width. -2 The typedef name int_fastN_t designates the fastest signed integer type with a width - of at least N . The typedef name uint_fastN_t designates the fastest unsigned integer - type with a width of at least N . - - - - - 251) The designated type is not guaranteed to be fastest for all purposes; if the implementation has no clear - grounds for choosing one type over another, it will simply pick some integer type satisfying the - signedness and width requirements. - -[page 289] - -3 The following types are required: - int_fast8_t uint_fast8_t - int_fast16_t uint_fast16_t - int_fast32_t uint_fast32_t - int_fast64_t uint_fast64_t - All other types of this form are optional. - 7.20.1.4 Integer types capable of holding object pointers -1 The following type designates a signed integer type with the property that any valid - pointer to void can be converted to this type, then converted back to pointer to void, - and the result will compare equal to the original pointer: - intptr_t - The following type designates an unsigned integer type with the property that any valid - pointer to void can be converted to this type, then converted back to pointer to void, - and the result will compare equal to the original pointer: - uintptr_t - These types are optional. - 7.20.1.5 Greatest-width integer types -1 The following type designates a signed integer type capable of representing any value of - any signed integer type: - intmax_t - The following type designates an unsigned integer type capable of representing any value - of any unsigned integer type: - uintmax_t - These types are required. - 7.20.2 Limits of specified-width integer types -1 The following object-like macros specify the minimum and maximum limits of the types - declared in . Each macro name corresponds to a similar type name in - 7.20.1. -2 Each instance of any defined macro shall be replaced by a constant expression suitable - for use in #if preprocessing directives, and this expression shall have the same type as - would an expression that is an object of the corresponding type converted according to - the integer promotions. Its implementation-defined value shall be equal to or greater in - magnitude (absolute value) than the corresponding value given below, with the same sign, - except where stated to be exactly the given value. - -[page 290] - - 7.20.2.1 Limits of exact-width integer types -1 -- minimum values of exact-width signed integer types - INTN_MIN exactly -(2 N -1 ) - -- maximum values of exact-width signed integer types - INTN_MAX exactly 2 N -1 - 1 - -- maximum values of exact-width unsigned integer types - UINTN_MAX exactly 2 N - 1 - 7.20.2.2 Limits of minimum-width integer types -1 -- minimum values of minimum-width signed integer types - INT_LEASTN_MIN -(2 N -1 - 1) - -- maximum values of minimum-width signed integer types - INT_LEASTN_MAX 2 N -1 - 1 - -- maximum values of minimum-width unsigned integer types - UINT_LEASTN_MAX 2N - 1 - 7.20.2.3 Limits of fastest minimum-width integer types -1 -- minimum values of fastest minimum-width signed integer types - INT_FASTN_MIN -(2 N -1 - 1) - -- maximum values of fastest minimum-width signed integer types - INT_FASTN_MAX 2 N -1 - 1 - -- maximum values of fastest minimum-width unsigned integer types - UINT_FASTN_MAX 2N - 1 - 7.20.2.4 Limits of integer types capable of holding object pointers -1 -- minimum value of pointer-holding signed integer type - INTPTR_MIN -(215 - 1) - -- maximum value of pointer-holding signed integer type - INTPTR_MAX 215 - 1 - -- maximum value of pointer-holding unsigned integer type - UINTPTR_MAX 216 - 1 - - - -[page 291] - - 7.20.2.5 Limits of greatest-width integer types -1 -- minimum value of greatest-width signed integer type - INTMAX_MIN -(263 - 1) - -- maximum value of greatest-width signed integer type - INTMAX_MAX 263 - 1 - -- maximum value of greatest-width unsigned integer type - UINTMAX_MAX 264 - 1 - 7.20.3 Limits of other integer types -1 The following object-like macros specify the minimum and maximum limits of integer - types corresponding to types defined in other standard headers. -2 Each instance of these macros shall be replaced by a constant expression suitable for use - in #if preprocessing directives, and this expression shall have the same type as would an - expression that is an object of the corresponding type converted according to the integer - promotions. Its implementation-defined value shall be equal to or greater in magnitude - (absolute value) than the corresponding value given below, with the same sign. An - implementation shall define only the macros corresponding to those typedef names it - actually provides.252) - -- limits of ptrdiff_t - PTRDIFF_MIN -65535 - PTRDIFF_MAX +65535 - -- limits of sig_atomic_t - SIG_ATOMIC_MIN see below - SIG_ATOMIC_MAX see below - -- limit of size_t - SIZE_MAX 65535 - -- limits of wchar_t - WCHAR_MIN see below - WCHAR_MAX see below - -- limits of wint_t - - - - - 252) A freestanding implementation need not provide all of these types. - -[page 292] - - WINT_MIN see below - WINT_MAX see below -3 If sig_atomic_t (see 7.14) is defined as a signed integer type, the value of - SIG_ATOMIC_MIN shall be no greater than -127 and the value of SIG_ATOMIC_MAX - shall be no less than 127; otherwise, sig_atomic_t is defined as an unsigned integer - type, and the value of SIG_ATOMIC_MIN shall be 0 and the value of - SIG_ATOMIC_MAX shall be no less than 255. -4 If wchar_t (see 7.19) is defined as a signed integer type, the value of WCHAR_MIN - shall be no greater than -127 and the value of WCHAR_MAX shall be no less than 127; - otherwise, wchar_t is defined as an unsigned integer type, and the value of - WCHAR_MIN shall be 0 and the value of WCHAR_MAX shall be no less than 255.253) -5 If wint_t (see 7.28) is defined as a signed integer type, the value of WINT_MIN shall - be no greater than -32767 and the value of WINT_MAX shall be no less than 32767; - otherwise, wint_t is defined as an unsigned integer type, and the value of WINT_MIN - shall be 0 and the value of WINT_MAX shall be no less than 65535. - 7.20.4 Macros for integer constants -1 The following function-like macros expand to integer constants suitable for initializing - objects that have integer types corresponding to types defined in . Each - macro name corresponds to a similar type name in 7.20.1.2 or 7.20.1.5. -2 The argument in any instance of these macros shall be an unsuffixed integer constant (as - defined in 6.4.4.1) with a value that does not exceed the limits for the corresponding type. -3 Each invocation of one of these macros shall expand to an integer constant expression - suitable for use in #if preprocessing directives. The type of the expression shall have - the same type as would an expression of the corresponding type converted according to - the integer promotions. The value of the expression shall be that of the argument. - 7.20.4.1 Macros for minimum-width integer constants -1 The macro INTN_C(value) shall expand to an integer constant expression - corresponding to the type int_leastN_t. The macro UINTN_C(value) shall expand - to an integer constant expression corresponding to the type uint_leastN_t. For - example, if uint_least64_t is a name for the type unsigned long long int, - then UINT64_C(0x123) might expand to the integer constant 0x123ULL. - - - - - 253) The values WCHAR_MIN and WCHAR_MAX do not necessarily correspond to members of the extended - character set. - -[page 293] - - 7.20.4.2 Macros for greatest-width integer constants -1 The following macro expands to an integer constant expression having the value specified - by its argument and the type intmax_t: - INTMAX_C(value) - The following macro expands to an integer constant expression having the value specified - by its argument and the type uintmax_t: - UINTMAX_C(value) - - - - -[page 294] - - 7.21 Input/output - 7.21.1 Introduction -1 The header defines several macros, and declares three types and many - functions for performing input and output. -2 The types declared are size_t (described in 7.19); - FILE - which is an object type capable of recording all the information needed to control a - stream, including its file position indicator, a pointer to its associated buffer (if any), an - error indicator that records whether a read/write error has occurred, and an end-of-file - indicator that records whether the end of the file has been reached; and - fpos_t - which is a complete object type other than an array type capable of recording all the - information needed to specify uniquely every position within a file. -3 The macros are NULL (described in 7.19); - _IOFBF - _IOLBF - _IONBF - which expand to integer constant expressions with distinct values, suitable for use as the - third argument to the setvbuf function; - BUFSIZ - which expands to an integer constant expression that is the size of the buffer used by the - setbuf function; - EOF - which expands to an integer constant expression, with type int and a negative value, that - is returned by several functions to indicate end-of-file, that is, no more input from a - stream; - FOPEN_MAX - which expands to an integer constant expression that is the minimum number of files that - the implementation guarantees can be open simultaneously; - FILENAME_MAX - which expands to an integer constant expression that is the size needed for an array of - char large enough to hold the longest file name string that the implementation - - - -[page 295] - - guarantees can be opened;254) - L_tmpnam - which expands to an integer constant expression that is the size needed for an array of - char large enough to hold a temporary file name string generated by the tmpnam - function; - SEEK_CUR - SEEK_END - SEEK_SET - which expand to integer constant expressions with distinct values, suitable for use as the - third argument to the fseek function; - TMP_MAX - which expands to an integer constant expression that is the minimum number of unique - file names that can be generated by the tmpnam function; - stderr - stdin - stdout - which are expressions of type ''pointer to FILE'' that point to the FILE objects - associated, respectively, with the standard error, input, and output streams. -4 The header declares a number of functions useful for wide character input - and output. The wide character input/output functions described in that subclause - provide operations analogous to most of those described here, except that the - fundamental units internal to the program are wide characters. The external - representation (in the file) is a sequence of ''generalized'' multibyte characters, as - described further in 7.21.3. -5 The input/output functions are given the following collective terms: - -- The wide character input functions -- those functions described in 7.28 that perform - input into wide characters and wide strings: fgetwc, fgetws, getwc, getwchar, - fwscanf, wscanf, vfwscanf, and vwscanf. - -- The wide character output functions -- those functions described in 7.28 that perform - output from wide characters and wide strings: fputwc, fputws, putwc, - putwchar, fwprintf, wprintf, vfwprintf, and vwprintf. - - - 254) If the implementation imposes no practical limit on the length of file name strings, the value of - FILENAME_MAX should instead be the recommended size of an array intended to hold a file name - string. Of course, file name string contents are subject to other system-specific constraints; therefore - all possible strings of length FILENAME_MAX cannot be expected to be opened successfully. - -[page 296] - - -- The wide character input/output functions -- the union of the ungetwc function, the - wide character input functions, and the wide character output functions. - -- The byte input/output functions -- those functions described in this subclause that - perform input/output: fgetc, fgets, fprintf, fputc, fputs, fread, - fscanf, fwrite, getc, getchar, printf, putc, putchar, puts, scanf, - ungetc, vfprintf, vfscanf, vprintf, and vscanf. - Forward references: files (7.21.3), the fseek function (7.21.9.2), streams (7.21.2), the - tmpnam function (7.21.4.4), (7.28). - 7.21.2 Streams -1 Input and output, whether to or from physical devices such as terminals and tape drives, - or whether to or from files supported on structured storage devices, are mapped into - logical data streams, whose properties are more uniform than their various inputs and - outputs. Two forms of mapping are supported, for text streams and for binary - streams.255) -2 A text stream is an ordered sequence of characters composed into lines, each line - consisting of zero or more characters plus a terminating new-line character. Whether the - last line requires a terminating new-line character is implementation-defined. Characters - may have to be added, altered, or deleted on input and output to conform to differing - conventions for representing text in the host environment. Thus, there need not be a one- - to-one correspondence between the characters in a stream and those in the external - representation. Data read in from a text stream will necessarily compare equal to the data - that were earlier written out to that stream only if: the data consist only of printing - characters and the control characters horizontal tab and new-line; no new-line character is - immediately preceded by space characters; and the last character is a new-line character. - Whether space characters that are written out immediately before a new-line character - appear when read in is implementation-defined. -3 A binary stream is an ordered sequence of characters that can transparently record - internal data. Data read in from a binary stream shall compare equal to the data that were - earlier written out to that stream, under the same implementation. Such a stream may, - however, have an implementation-defined number of null characters appended to the end - of the stream. -4 Each stream has an orientation. After a stream is associated with an external file, but - before any operations are performed on it, the stream is without orientation. Once a wide - character input/output function has been applied to a stream without orientation, the - - - 255) An implementation need not distinguish between text streams and binary streams. In such an - implementation, there need be no new-line characters in a text stream nor any limit to the length of a - line. - -[page 297] - - stream becomes a wide-oriented stream. Similarly, once a byte input/output function has - been applied to a stream without orientation, the stream becomes a byte-oriented stream. - Only a call to the freopen function or the fwide function can otherwise alter the - orientation of a stream. (A successful call to freopen removes any orientation.)256) -5 Byte input/output functions shall not be applied to a wide-oriented stream and wide - character input/output functions shall not be applied to a byte-oriented stream. The - remaining stream operations do not affect, and are not affected by, a stream's orientation, - except for the following additional restrictions: - -- Binary wide-oriented streams have the file-positioning restrictions ascribed to both - text and binary streams. - -- For wide-oriented streams, after a successful call to a file-positioning function that - leaves the file position indicator prior to the end-of-file, a wide character output - function can overwrite a partial multibyte character; any file contents beyond the - byte(s) written are henceforth indeterminate. -6 Each wide-oriented stream has an associated mbstate_t object that stores the current - parse state of the stream. A successful call to fgetpos stores a representation of the - value of this mbstate_t object as part of the value of the fpos_t object. A later - successful call to fsetpos using the same stored fpos_t value restores the value of - the associated mbstate_t object as well as the position within the controlled stream. - Environmental limits -7 An implementation shall support text files with lines containing at least 254 characters, - including the terminating new-line character. The value of the macro BUFSIZ shall be at - least 256. - Forward references: the freopen function (7.21.5.4), the fwide function (7.28.3.5), - mbstate_t (7.29.1), the fgetpos function (7.21.9.1), the fsetpos function - (7.21.9.3). - - - - - 256) The three predefined streams stdin, stdout, and stderr are unoriented at program startup. - -[page 298] - - 7.21.3 Files -1 A stream is associated with an external file (which may be a physical device) by opening - a file, which may involve creating a new file. Creating an existing file causes its former - contents to be discarded, if necessary. If a file can support positioning requests (such as a - disk file, as opposed to a terminal), then a file position indicator associated with the - stream is positioned at the start (character number zero) of the file, unless the file is - opened with append mode in which case it is implementation-defined whether the file - position indicator is initially positioned at the beginning or the end of the file. The file - position indicator is maintained by subsequent reads, writes, and positioning requests, to - facilitate an orderly progression through the file. -2 Binary files are not truncated, except as defined in 7.21.5.3. Whether a write on a text - stream causes the associated file to be truncated beyond that point is implementation- - defined. -3 When a stream is unbuffered, characters are intended to appear from the source or at the - destination as soon as possible. Otherwise characters may be accumulated and - transmitted to or from the host environment as a block. When a stream is fully buffered, - characters are intended to be transmitted to or from the host environment as a block when - a buffer is filled. When a stream is line buffered, characters are intended to be - transmitted to or from the host environment as a block when a new-line character is - encountered. Furthermore, characters are intended to be transmitted as a block to the host - environment when a buffer is filled, when input is requested on an unbuffered stream, or - when input is requested on a line buffered stream that requires the transmission of - characters from the host environment. Support for these characteristics is - implementation-defined, and may be affected via the setbuf and setvbuf functions. -4 A file may be disassociated from a controlling stream by closing the file. Output streams - are flushed (any unwritten buffer contents are transmitted to the host environment) before - the stream is disassociated from the file. The value of a pointer to a FILE object is - indeterminate after the associated file is closed (including the standard text streams). - Whether a file of zero length (on which no characters have been written by an output - stream) actually exists is implementation-defined. -5 The file may be subsequently reopened, by the same or another program execution, and - its contents reclaimed or modified (if it can be repositioned at its start). If the main - function returns to its original caller, or if the exit function is called, all open files are - closed (hence all output streams are flushed) before program termination. Other paths to - program termination, such as calling the abort function, need not close all files - properly. -6 The address of the FILE object used to control a stream may be significant; a copy of a - FILE object need not serve in place of the original. - -[page 299] - -7 At program startup, three text streams are predefined and need not be opened explicitly - -- standard input (for reading conventional input), standard output (for writing - conventional output), and standard error (for writing diagnostic output). As initially - opened, the standard error stream is not fully buffered; the standard input and standard - output streams are fully buffered if and only if the stream can be determined not to refer - to an interactive device. -8 Functions that open additional (nontemporary) files require a file name, which is a string. - The rules for composing valid file names are implementation-defined. Whether the same - file can be simultaneously open multiple times is also implementation-defined. -9 Although both text and binary wide-oriented streams are conceptually sequences of wide - characters, the external file associated with a wide-oriented stream is a sequence of - multibyte characters, generalized as follows: - -- Multibyte encodings within files may contain embedded null bytes (unlike multibyte - encodings valid for use internal to the program). - -- A file need not begin nor end in the initial shift state.257) -10 Moreover, the encodings used for multibyte characters may differ among files. Both the - nature and choice of such encodings are implementation-defined. -11 The wide character input functions read multibyte characters from the stream and convert - them to wide characters as if they were read by successive calls to the fgetwc function. - Each conversion occurs as if by a call to the mbrtowc function, with the conversion state - described by the stream's own mbstate_t object. The byte input functions read - characters from the stream as if by successive calls to the fgetc function. -12 The wide character output functions convert wide characters to multibyte characters and - write them to the stream as if they were written by successive calls to the fputwc - function. Each conversion occurs as if by a call to the wcrtomb function, with the - conversion state described by the stream's own mbstate_t object. The byte output - functions write characters to the stream as if by successive calls to the fputc function. -13 In some cases, some of the byte input/output functions also perform conversions between - multibyte characters and wide characters. These conversions also occur as if by calls to - the mbrtowc and wcrtomb functions. -14 An encoding error occurs if the character sequence presented to the underlying - mbrtowc function does not form a valid (generalized) multibyte character, or if the code - value passed to the underlying wcrtomb does not correspond to a valid (generalized) - - - 257) Setting the file position indicator to end-of-file, as with fseek(file, 0, SEEK_END), has - undefined behavior for a binary stream (because of possible trailing null characters) or for any stream - with state-dependent encoding that does not assuredly end in the initial shift state. - -[page 300] - - multibyte character. The wide character input/output functions and the byte input/output - functions store the value of the macro EILSEQ in errno if and only if an encoding error - occurs. - Environmental limits -15 The value of FOPEN_MAX shall be at least eight, including the three standard text - streams. - Forward references: the exit function (7.22.4.4), the fgetc function (7.21.7.1), the - fopen function (7.21.5.3), the fputc function (7.21.7.3), the setbuf function - (7.21.5.5), the setvbuf function (7.21.5.6), the fgetwc function (7.28.3.1), the - fputwc function (7.28.3.3), conversion state (7.28.6), the mbrtowc function - (7.28.6.3.2), the wcrtomb function (7.28.6.3.3). - 7.21.4 Operations on files - 7.21.4.1 The remove function - Synopsis -1 #include - int remove(const char *filename); - Description -2 The remove function causes the file whose name is the string pointed to by filename - to be no longer accessible by that name. A subsequent attempt to open that file using that - name will fail, unless it is created anew. If the file is open, the behavior of the remove - function is implementation-defined. - Returns -3 The remove function returns zero if the operation succeeds, nonzero if it fails. - 7.21.4.2 The rename function - Synopsis -1 #include - int rename(const char *old, const char *new); - Description -2 The rename function causes the file whose name is the string pointed to by old to be - henceforth known by the name given by the string pointed to by new. The file named - old is no longer accessible by that name. If a file named by the string pointed to by new - exists prior to the call to the rename function, the behavior is implementation-defined. - - - - -[page 301] - - Returns -3 The rename function returns zero if the operation succeeds, nonzero if it fails,258) in - which case if the file existed previously it is still known by its original name. - 7.21.4.3 The tmpfile function - Synopsis -1 #include - FILE *tmpfile(void); - Description -2 The tmpfile function creates a temporary binary file that is different from any other - existing file and that will automatically be removed when it is closed or at program - termination. If the program terminates abnormally, whether an open temporary file is - removed is implementation-defined. The file is opened for update with "wb+" mode. - Recommended practice -3 It should be possible to open at least TMP_MAX temporary files during the lifetime of the - program (this limit may be shared with tmpnam) and there should be no limit on the - number simultaneously open other than this limit and any limit on the number of open - files (FOPEN_MAX). - Returns -4 The tmpfile function returns a pointer to the stream of the file that it created. If the file - cannot be created, the tmpfile function returns a null pointer. - Forward references: the fopen function (7.21.5.3). - 7.21.4.4 The tmpnam function - Synopsis -1 #include - char *tmpnam(char *s); - Description -2 The tmpnam function generates a string that is a valid file name and that is not the same - as the name of an existing file.259) The function is potentially capable of generating at - - - 258) Among the reasons the implementation may cause the rename function to fail are that the file is open - or that it is necessary to copy its contents to effectuate its renaming. - 259) Files created using strings generated by the tmpnam function are temporary only in the sense that - their names should not collide with those generated by conventional naming rules for the - implementation. It is still necessary to use the remove function to remove such files when their use - is ended, and before program termination. - -[page 302] - - least TMP_MAX different strings, but any or all of them may already be in use by existing - files and thus not be suitable return values. -3 The tmpnam function generates a different string each time it is called. -4 Calls to the tmpnam function with a null pointer argument may introduce data races with - each other. The implementation shall behave as if no library function calls the tmpnam - function. - Returns -5 If no suitable string can be generated, the tmpnam function returns a null pointer. - Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an - internal static object and returns a pointer to that object (subsequent calls to the tmpnam - function may modify the same object). If the argument is not a null pointer, it is assumed - to point to an array of at least L_tmpnam chars; the tmpnam function writes its result - in that array and returns the argument as its value. - Environmental limits -6 The value of the macro TMP_MAX shall be at least 25. - 7.21.5 File access functions - 7.21.5.1 The fclose function - Synopsis -1 #include - int fclose(FILE *stream); - Description -2 A successful call to the fclose function causes the stream pointed to by stream to be - flushed and the associated file to be closed. Any unwritten buffered data for the stream - are delivered to the host environment to be written to the file; any unread buffered data - are discarded. Whether or not the call succeeds, the stream is disassociated from the file - and any buffer set by the setbuf or setvbuf function is disassociated from the stream - (and deallocated if it was automatically allocated). - Returns -3 The fclose function returns zero if the stream was successfully closed, or EOF if any - errors were detected. - - - - -[page 303] - - 7.21.5.2 The fflush function - Synopsis -1 #include - int fflush(FILE *stream); - Description -2 If stream points to an output stream or an update stream in which the most recent - operation was not input, the fflush function causes any unwritten data for that stream - to be delivered to the host environment to be written to the file; otherwise, the behavior is - undefined. -3 If stream is a null pointer, the fflush function performs this flushing action on all - streams for which the behavior is defined above. - Returns -4 The fflush function sets the error indicator for the stream and returns EOF if a write - error occurs, otherwise it returns zero. - Forward references: the fopen function (7.21.5.3). - 7.21.5.3 The fopen function - Synopsis -1 #include - FILE *fopen(const char * restrict filename, - const char * restrict mode); - Description -2 The fopen function opens the file whose name is the string pointed to by filename, - and associates a stream with it. -3 The argument mode points to a string. If the string is one of the following, the file is - open in the indicated mode. Otherwise, the behavior is undefined.260) - r open text file for reading - w truncate to zero length or create text file for writing - wx create text file for writing - a append; open or create text file for writing at end-of-file - rb open binary file for reading - wb truncate to zero length or create binary file for writing - - - 260) If the string begins with one of the above sequences, the implementation might choose to ignore the - remaining characters, or it might use them to select different kinds of a file (some of which might not - conform to the properties in 7.21.2). - -[page 304] - - wbx create binary file for writing - ab append; open or create binary file for writing at end-of-file - r+ open text file for update (reading and writing) - w+ truncate to zero length or create text file for update - w+x create text file for update - a+ append; open or create text file for update, writing at end-of-file - r+b or rb+ open binary file for update (reading and writing) - w+b or wb+ truncate to zero length or create binary file for update - w+bx or wb+x create binary file for update - a+b or ab+ append; open or create binary file for update, writing at end-of-file -4 Opening a file with read mode ('r' as the first character in the mode argument) fails if - the file does not exist or cannot be read. -5 Opening a file with exclusive mode ('x' as the last character in the mode argument) - fails if the file already exists or cannot be created. Otherwise, the file is created with - exclusive (also known as non-shared) access to the extent that the underlying system - supports exclusive access. -6 Opening a file with append mode ('a' as the first character in the mode argument) - causes all subsequent writes to the file to be forced to the then current end-of-file, - regardless of intervening calls to the fseek function. In some implementations, opening - a binary file with append mode ('b' as the second or third character in the above list of - mode argument values) may initially position the file position indicator for the stream - beyond the last data written, because of null character padding. -7 When a file is opened with update mode ('+' as the second or third character in the - above list of mode argument values), both input and output may be performed on the - associated stream. However, output shall not be directly followed by input without an - intervening call to the fflush function or to a file positioning function (fseek, - fsetpos, or rewind), and input shall not be directly followed by output without an - intervening call to a file positioning function, unless the input operation encounters end- - of-file. Opening (or creating) a text file with update mode may instead open (or create) a - binary stream in some implementations. -8 When opened, a stream is fully buffered if and only if it can be determined not to refer to - an interactive device. The error and end-of-file indicators for the stream are cleared. - Returns -9 The fopen function returns a pointer to the object controlling the stream. If the open - operation fails, fopen returns a null pointer. - Forward references: file positioning functions (7.21.9). - - - -[page 305] - - 7.21.5.4 The freopen function - Synopsis -1 #include - FILE *freopen(const char * restrict filename, - const char * restrict mode, - FILE * restrict stream); - Description -2 The freopen function opens the file whose name is the string pointed to by filename - and associates the stream pointed to by stream with it. The mode argument is used just - as in the fopen function.261) -3 If filename is a null pointer, the freopen function attempts to change the mode of - the stream to that specified by mode, as if the name of the file currently associated with - the stream had been used. It is implementation-defined which changes of mode are - permitted (if any), and under what circumstances. -4 The freopen function first attempts to close any file that is associated with the specified - stream. Failure to close the file is ignored. The error and end-of-file indicators for the - stream are cleared. - Returns -5 The freopen function returns a null pointer if the open operation fails. Otherwise, - freopen returns the value of stream. - 7.21.5.5 The setbuf function - Synopsis -1 #include - void setbuf(FILE * restrict stream, - char * restrict buf); - Description -2 Except that it returns no value, the setbuf function is equivalent to the setvbuf - function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf - is a null pointer), with the value _IONBF for mode. - - - - - 261) The primary use of the freopen function is to change the file associated with a standard text stream - (stderr, stdin, or stdout), as those identifiers need not be modifiable lvalues to which the value - returned by the fopen function may be assigned. - -[page 306] - - Returns -3 The setbuf function returns no value. - Forward references: the setvbuf function (7.21.5.6). - 7.21.5.6 The setvbuf function - Synopsis -1 #include - int setvbuf(FILE * restrict stream, - char * restrict buf, - int mode, size_t size); - Description -2 The setvbuf function may be used only after the stream pointed to by stream has - been associated with an open file and before any other operation (other than an - unsuccessful call to setvbuf) is performed on the stream. The argument mode - determines how stream will be buffered, as follows: _IOFBF causes input/output to be - fully buffered; _IOLBF causes input/output to be line buffered; _IONBF causes - input/output to be unbuffered. If buf is not a null pointer, the array it points to may be - used instead of a buffer allocated by the setvbuf function262) and the argument size - specifies the size of the array; otherwise, size may determine the size of a buffer - allocated by the setvbuf function. The contents of the array at any time are - indeterminate. - Returns -3 The setvbuf function returns zero on success, or nonzero if an invalid value is given - for mode or if the request cannot be honored. - - - - - 262) The buffer has to have a lifetime at least as great as the open stream, so the stream should be closed - before a buffer that has automatic storage duration is deallocated upon block exit. - -[page 307] - - 7.21.6 Formatted input/output functions -1 The formatted input/output functions shall behave as if there is a sequence point after the - actions associated with each specifier.263) - 7.21.6.1 The fprintf function - Synopsis -1 #include - int fprintf(FILE * restrict stream, - const char * restrict format, ...); - Description -2 The fprintf function writes output to the stream pointed to by stream, under control - of the string pointed to by format that specifies how subsequent arguments are - converted for output. If there are insufficient arguments for the format, the behavior is - undefined. If the format is exhausted while arguments remain, the excess arguments are - evaluated (as always) but are otherwise ignored. The fprintf function returns when - the end of the format string is encountered. -3 The format shall be a multibyte character sequence, beginning and ending in its initial - shift state. The format is composed of zero or more directives: ordinary multibyte - characters (not %), which are copied unchanged to the output stream; and conversion - specifications, each of which results in fetching zero or more subsequent arguments, - converting them, if applicable, according to the corresponding conversion specifier, and - then writing the result to the output stream. -4 Each conversion specification is introduced by the character %. After the %, the following - appear in sequence: - -- Zero or more flags (in any order) that modify the meaning of the conversion - specification. - -- An optional minimum field width. If the converted value has fewer characters than the - field width, it is padded with spaces (by default) on the left (or right, if the left - adjustment flag, described later, has been given) to the field width. The field width - takes the form of an asterisk * (described later) or a nonnegative decimal integer.264) - -- An optional precision that gives the minimum number of digits to appear for the d, i, - o, u, x, and X conversions, the number of digits to appear after the decimal-point - character for a, A, e, E, f, and F conversions, the maximum number of significant - digits for the g and G conversions, or the maximum number of bytes to be written for - - - 263) The fprintf functions perform writes to memory for the %n specifier. - 264) Note that 0 is taken as a flag, not as the beginning of a field width. - -[page 308] - - s conversions. The precision takes the form of a period (.) followed either by an - asterisk * (described later) or by an optional decimal integer; if only the period is - specified, the precision is taken as zero. If a precision appears with any other - conversion specifier, the behavior is undefined. - -- An optional length modifier that specifies the size of the argument. - -- A conversion specifier character that specifies the type of conversion to be applied. -5 As noted above, a field width, or precision, or both, may be indicated by an asterisk. In - this case, an int argument supplies the field width or precision. The arguments - specifying field width, or precision, or both, shall appear (in that order) before the - argument (if any) to be converted. A negative field width argument is taken as a - flag - followed by a positive field width. A negative precision argument is taken as if the - precision were omitted. -6 The flag characters and their meanings are: - - The result of the conversion is left-justified within the field. (It is right-justified if - this flag is not specified.) - + The result of a signed conversion always begins with a plus or minus sign. (It - begins with a sign only when a negative value is converted if this flag is not - specified.)265) - space If the first character of a signed conversion is not a sign, or if a signed conversion - results in no characters, a space is prefixed to the result. If the space and + flags - both appear, the space flag is ignored. - # The result is converted to an ''alternative form''. For o conversion, it increases - the precision, if and only if necessary, to force the first digit of the result to be a - zero (if the value and precision are both 0, a single 0 is printed). For x (or X) - conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g, - and G conversions, the result of converting a floating-point number always - contains a decimal-point character, even if no digits follow it. (Normally, a - decimal-point character appears in the result of these conversions only if a digit - follows it.) For g and G conversions, trailing zeros are not removed from the - result. For other conversions, the behavior is undefined. - 0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros - (following any indication of sign or base) are used to pad to the field width rather - than performing space padding, except when converting an infinity or NaN. If the - 0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X - - - 265) The results of all floating conversions of a negative zero, and of negative values that round to zero, - include a minus sign. - -[page 309] - - conversions, if a precision is specified, the 0 flag is ignored. For other - conversions, the behavior is undefined. -7 The length modifiers and their meanings are: - hh Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - signed char or unsigned char argument (the argument will have - been promoted according to the integer promotions, but its value shall be - converted to signed char or unsigned char before printing); or that - a following n conversion specifier applies to a pointer to a signed char - argument. - h Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - short int or unsigned short int argument (the argument will - have been promoted according to the integer promotions, but its value shall - be converted to short int or unsigned short int before printing); - or that a following n conversion specifier applies to a pointer to a short - int argument. - l (ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - long int or unsigned long int argument; that a following n - conversion specifier applies to a pointer to a long int argument; that a - following c conversion specifier applies to a wint_t argument; that a - following s conversion specifier applies to a pointer to a wchar_t - argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion - specifier. - ll (ell-ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - long long int or unsigned long long int argument; or that a - following n conversion specifier applies to a pointer to a long long int - argument. - j Specifies that a following d, i, o, u, x, or X conversion specifier applies to - an intmax_t or uintmax_t argument; or that a following n conversion - specifier applies to a pointer to an intmax_t argument. - z Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - size_t or the corresponding signed integer type argument; or that a - following n conversion specifier applies to a pointer to a signed integer type - corresponding to size_t argument. - t Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - ptrdiff_t or the corresponding unsigned integer type argument; or that a - following n conversion specifier applies to a pointer to a ptrdiff_t - argument. - - -[page 310] - - L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier - applies to a long double argument. - If a length modifier appears with any conversion specifier other than as specified above, - the behavior is undefined. -8 The conversion specifiers and their meanings are: - d,i The int argument is converted to signed decimal in the style [-]dddd. The - precision specifies the minimum number of digits to appear; if the value - being converted can be represented in fewer digits, it is expanded with - leading zeros. The default precision is 1. The result of converting a zero - value with a precision of zero is no characters. - o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned - decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the - letters abcdef are used for x conversion and the letters ABCDEF for X - conversion. The precision specifies the minimum number of digits to appear; - if the value being converted can be represented in fewer digits, it is expanded - with leading zeros. The default precision is 1. The result of converting a - zero value with a precision of zero is no characters. - f,F A double argument representing a floating-point number is converted to - decimal notation in the style [-]ddd.ddd, where the number of digits after - the decimal-point character is equal to the precision specification. If the - precision is missing, it is taken as 6; if the precision is zero and the # flag is - not specified, no decimal-point character appears. If a decimal-point - character appears, at least one digit appears before it. The value is rounded to - the appropriate number of digits. - A double argument representing an infinity is converted in one of the styles - [-]inf or [-]infinity -- which style is implementation-defined. A - double argument representing a NaN is converted in one of the styles - [-]nan or [-]nan(n-char-sequence) -- which style, and the meaning of - any n-char-sequence, is implementation-defined. The F conversion specifier - produces INF, INFINITY, or NAN instead of inf, infinity, or nan, - respectively.266) - e,E A double argument representing a floating-point number is converted in the - style [-]d.ddd e(+-)dd, where there is one digit (which is nonzero if the - argument is nonzero) before the decimal-point character and the number of - digits after it is equal to the precision; if the precision is missing, it is taken as - - - 266) When applied to infinite and NaN values, the -, +, and space flag characters have their usual meaning; - the # and 0 flag characters have no effect. - -[page 311] - - 6; if the precision is zero and the # flag is not specified, no decimal-point - character appears. The value is rounded to the appropriate number of digits. - The E conversion specifier produces a number with E instead of e - introducing the exponent. The exponent always contains at least two digits, - and only as many more digits as necessary to represent the exponent. If the - value is zero, the exponent is zero. - A double argument representing an infinity or NaN is converted in the style - of an f or F conversion specifier. -g,G A double argument representing a floating-point number is converted in - style f or e (or in style F or E in the case of a G conversion specifier), - depending on the value converted and the precision. Let P equal the - precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. - Then, if a conversion with style E would have an exponent of X: - -- if P > X >= -4, the conversion is with style f (or F) and precision - P - (X + 1). - -- otherwise, the conversion is with style e (or E) and precision P - 1. - Finally, unless the # flag is used, any trailing zeros are removed from the - fractional portion of the result and the decimal-point character is removed if - there is no fractional portion remaining. - A double argument representing an infinity or NaN is converted in the style - of an f or F conversion specifier. -a,A A double argument representing a floating-point number is converted in the - style [-]0xh.hhhh p(+-)d, where there is one hexadecimal digit (which is - nonzero if the argument is a normalized floating-point number and is - otherwise unspecified) before the decimal-point character267) and the number - of hexadecimal digits after it is equal to the precision; if the precision is - missing and FLT_RADIX is a power of 2, then the precision is sufficient for - an exact representation of the value; if the precision is missing and - FLT_RADIX is not a power of 2, then the precision is sufficient to - - - - -267) Binary implementations can choose the hexadecimal digit to the left of the decimal-point character so - that subsequent digits align to nibble (4-bit) boundaries. - -[page 312] - - distinguish268) values of type double, except that trailing zeros may be - omitted; if the precision is zero and the # flag is not specified, no decimal- - point character appears. The letters abcdef are used for a conversion and - the letters ABCDEF for A conversion. The A conversion specifier produces a - number with X and P instead of x and p. The exponent always contains at - least one digit, and only as many more digits as necessary to represent the - decimal exponent of 2. If the value is zero, the exponent is zero. - A double argument representing an infinity or NaN is converted in the style - of an f or F conversion specifier. -c If no l length modifier is present, the int argument is converted to an - unsigned char, and the resulting character is written. - If an l length modifier is present, the wint_t argument is converted as if by - an ls conversion specification with no precision and an argument that points - to the initial element of a two-element array of wchar_t, the first element - containing the wint_t argument to the lc conversion specification and the - second a null wide character. -s If no l length modifier is present, the argument shall be a pointer to the initial - element of an array of character type.269) Characters from the array are - written up to (but not including) the terminating null character. If the - precision is specified, no more than that many bytes are written. If the - precision is not specified or is greater than the size of the array, the array shall - contain a null character. - If an l length modifier is present, the argument shall be a pointer to the initial - element of an array of wchar_t type. Wide characters from the array are - converted to multibyte characters (each as if by a call to the wcrtomb - function, with the conversion state described by an mbstate_t object - initialized to zero before the first wide character is converted) up to and - including a terminating null wide character. The resulting multibyte - characters are written up to (but not including) the terminating null character - (byte). If no precision is specified, the array shall contain a null wide - character. If a precision is specified, no more than that many bytes are - written (including shift sequences, if any), and the array shall contain a null - wide character if, to equal the multibyte character sequence length given by - -268) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is - FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p - might suffice depending on the implementation's scheme for determining the digit to the left of the - decimal-point character. -269) No special provisions are made for multibyte characters. - -[page 313] - - the precision, the function would need to access a wide character one past the - end of the array. In no case is a partial multibyte character written.270) - p The argument shall be a pointer to void. The value of the pointer is - converted to a sequence of printing characters, in an implementation-defined - manner. - n The argument shall be a pointer to signed integer into which is written the - number of characters written to the output stream so far by this call to - fprintf. No argument is converted, but one is consumed. If the conversion - specification includes any flags, a field width, or a precision, the behavior is - undefined. - % A % character is written. No argument is converted. The complete - conversion specification shall be %%. -9 If a conversion specification is invalid, the behavior is undefined.271) If any argument is - not the correct type for the corresponding conversion specification, the behavior is - undefined. -10 In no case does a nonexistent or small field width cause truncation of a field; if the result - of a conversion is wider than the field width, the field is expanded to contain the - conversion result. -11 For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded - to a hexadecimal floating number with the given precision. - Recommended practice -12 For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly - representable in the given precision, the result should be one of the two adjacent numbers - in hexadecimal floating style with the given precision, with the extra stipulation that the - error should have a correct sign for the current rounding direction. -13 For e, E, f, F, g, and G conversions, if the number of significant decimal digits is at most - DECIMAL_DIG, then the result should be correctly rounded.272) If the number of - significant decimal digits is more than DECIMAL_DIG but the source value is exactly - representable with DECIMAL_DIG digits, then the result should be an exact - representation with trailing zeros. Otherwise, the source value is bounded by two - adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value - - - 270) Redundant shift sequences may result if multibyte characters have a state-dependent encoding. - 271) See ''future library directions'' (7.30.9). - 272) For binary-to-decimal conversion, the result format's values are the numbers representable with the - given format specifier. The number of significant digits is determined by the format specifier, and in - the case of fixed-point conversion by the source value as well. - -[page 314] - - of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that - the error should have a correct sign for the current rounding direction. - Returns -14 The fprintf function returns the number of characters transmitted, or a negative value - if an output or encoding error occurred. - Environmental limits -15 The number of characters that can be produced by any single conversion shall be at least - 4095. -16 EXAMPLE 1 To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal - places: - #include - #include - /* ... */ - char *weekday, *month; // pointers to strings - int day, hour, min; - fprintf(stdout, "%s, %s %d, %.2d:%.2d\n", - weekday, month, day, hour, min); - fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0)); - -17 EXAMPLE 2 In this example, multibyte characters do not have a state-dependent encoding, and the - members of the extended character set that consist of more than one byte each consist of exactly two bytes, - the first of which is denoted here by a and the second by an uppercase letter. -18 Given the following wide string with length seven, - static wchar_t wstr[] = L" X Yabc Z W"; - the seven calls - fprintf(stdout, "|1234567890123|\n"); - fprintf(stdout, "|%13ls|\n", wstr); - fprintf(stdout, "|%-13.9ls|\n", wstr); - fprintf(stdout, "|%13.10ls|\n", wstr); - fprintf(stdout, "|%13.11ls|\n", wstr); - fprintf(stdout, "|%13.15ls|\n", &wstr[2]); - fprintf(stdout, "|%13lc|\n", (wint_t) wstr[5]); - will print the following seven lines: - |1234567890123| - | X Yabc Z W| - | X Yabc Z | - | X Yabc Z| - | X Yabc Z W| - | abc Z W| - | Z| - - Forward references: conversion state (7.28.6), the wcrtomb function (7.28.6.3.3). - - - -[page 315] - - 7.21.6.2 The fscanf function - Synopsis -1 #include - int fscanf(FILE * restrict stream, - const char * restrict format, ...); - Description -2 The fscanf function reads input from the stream pointed to by stream, under control - of the string pointed to by format that specifies the admissible input sequences and how - they are to be converted for assignment, using subsequent arguments as pointers to the - objects to receive the converted input. If there are insufficient arguments for the format, - the behavior is undefined. If the format is exhausted while arguments remain, the excess - arguments are evaluated (as always) but are otherwise ignored. -3 The format shall be a multibyte character sequence, beginning and ending in its initial - shift state. The format is composed of zero or more directives: one or more white-space - characters, an ordinary multibyte character (neither % nor a white-space character), or a - conversion specification. Each conversion specification is introduced by the character %. - After the %, the following appear in sequence: - -- An optional assignment-suppressing character *. - -- An optional decimal integer greater than zero that specifies the maximum field width - (in characters). - -- An optional length modifier that specifies the size of the receiving object. - -- A conversion specifier character that specifies the type of conversion to be applied. -4 The fscanf function executes each directive of the format in turn. When all directives - have been executed, or if a directive fails (as detailed below), the function returns. - Failures are described as input failures (due to the occurrence of an encoding error or the - unavailability of input characters), or matching failures (due to inappropriate input). -5 A directive composed of white-space character(s) is executed by reading input up to the - first non-white-space character (which remains unread), or until no more characters can - be read. -6 A directive that is an ordinary multibyte character is executed by reading the next - characters of the stream. If any of those characters differ from the ones composing the - directive, the directive fails and the differing and subsequent characters remain unread. - Similarly, if end-of-file, an encoding error, or a read error prevents a character from being - read, the directive fails. -7 A directive that is a conversion specification defines a set of matching input sequences, as - described below for each specifier. A conversion specification is executed in the - -[page 316] - - following steps: -8 Input white-space characters (as specified by the isspace function) are skipped, unless - the specification includes a [, c, or n specifier.273) -9 An input item is read from the stream, unless the specification includes an n specifier. An - input item is defined as the longest sequence of input characters which does not exceed - any specified field width and which is, or is a prefix of, a matching input sequence.274) - The first character, if any, after the input item remains unread. If the length of the input - item is zero, the execution of the directive fails; this condition is a matching failure unless - end-of-file, an encoding error, or a read error prevented input from the stream, in which - case it is an input failure. -10 Except in the case of a % specifier, the input item (or, in the case of a %n directive, the - count of input characters) is converted to a type appropriate to the conversion specifier. If - the input item is not a matching sequence, the execution of the directive fails: this - condition is a matching failure. Unless assignment suppression was indicated by a *, the - result of the conversion is placed in the object pointed to by the first argument following - the format argument that has not already received a conversion result. If this object - does not have an appropriate type, or if the result of the conversion cannot be represented - in the object, the behavior is undefined. -11 The length modifiers and their meanings are: - hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to signed char or unsigned char. - h Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to short int or unsigned short - int. - l (ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to long int or unsigned long - int; that a following a, A, e, E, f, F, g, or G conversion specifier applies to - an argument with type pointer to double; or that a following c, s, or [ - conversion specifier applies to an argument with type pointer to wchar_t. - ll (ell-ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to long long int or unsigned - long long int. - - - - 273) These white-space characters are not counted against a specified field width. - 274) fscanf pushes back at most one input character onto the input stream. Therefore, some sequences - that are acceptable to strtod, strtol, etc., are unacceptable to fscanf. - -[page 317] - - j Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to intmax_t or uintmax_t. - z Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to size_t or the corresponding signed - integer type. - t Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to ptrdiff_t or the corresponding - unsigned integer type. - L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier - applies to an argument with type pointer to long double. - If a length modifier appears with any conversion specifier other than as specified above, - the behavior is undefined. -12 The conversion specifiers and their meanings are: - d Matches an optionally signed decimal integer, whose format is the same as - expected for the subject sequence of the strtol function with the value 10 - for the base argument. The corresponding argument shall be a pointer to - signed integer. - i Matches an optionally signed integer, whose format is the same as expected - for the subject sequence of the strtol function with the value 0 for the - base argument. The corresponding argument shall be a pointer to signed - integer. - o Matches an optionally signed octal integer, whose format is the same as - expected for the subject sequence of the strtoul function with the value 8 - for the base argument. The corresponding argument shall be a pointer to - unsigned integer. - u Matches an optionally signed decimal integer, whose format is the same as - expected for the subject sequence of the strtoul function with the value 10 - for the base argument. The corresponding argument shall be a pointer to - unsigned integer. - x Matches an optionally signed hexadecimal integer, whose format is the same - as expected for the subject sequence of the strtoul function with the value - 16 for the base argument. The corresponding argument shall be a pointer to - unsigned integer. - a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose - format is the same as expected for the subject sequence of the strtod - function. The corresponding argument shall be a pointer to floating. - - -[page 318] - -c Matches a sequence of characters of exactly the number specified by the field - width (1 if no field width is present in the directive).275) - If no l length modifier is present, the corresponding argument shall be a - pointer to the initial element of a character array large enough to accept the - sequence. No null character is added. - If an l length modifier is present, the input shall be a sequence of multibyte - characters that begins in the initial shift state. Each multibyte character in the - sequence is converted to a wide character as if by a call to the mbrtowc - function, with the conversion state described by an mbstate_t object - initialized to zero before the first multibyte character is converted. The - corresponding argument shall be a pointer to the initial element of an array of - wchar_t large enough to accept the resulting sequence of wide characters. - No null wide character is added. -s Matches a sequence of non-white-space characters.275) - If no l length modifier is present, the corresponding argument shall be a - pointer to the initial element of a character array large enough to accept the - sequence and a terminating null character, which will be added automatically. - If an l length modifier is present, the input shall be a sequence of multibyte - characters that begins in the initial shift state. Each multibyte character is - converted to a wide character as if by a call to the mbrtowc function, with - the conversion state described by an mbstate_t object initialized to zero - before the first multibyte character is converted. The corresponding argument - shall be a pointer to the initial element of an array of wchar_t large enough - to accept the sequence and the terminating null wide character, which will be - added automatically. -[ Matches a nonempty sequence of characters from a set of expected characters - (the scanset).275) - If no l length modifier is present, the corresponding argument shall be a - pointer to the initial element of a character array large enough to accept the - sequence and a terminating null character, which will be added automatically. - If an l length modifier is present, the input shall be a sequence of multibyte - characters that begins in the initial shift state. Each multibyte character is - converted to a wide character as if by a call to the mbrtowc function, with - the conversion state described by an mbstate_t object initialized to zero - -275) No special provisions are made for multibyte characters in the matching rules used by the c, s, and [ - conversion specifiers -- the extent of the input field is determined on a byte-by-byte basis. The - resulting field is nevertheless a sequence of multibyte characters that begins in the initial shift state. - -[page 319] - - before the first multibyte character is converted. The corresponding argument - shall be a pointer to the initial element of an array of wchar_t large enough - to accept the sequence and the terminating null wide character, which will be - added automatically. - The conversion specifier includes all subsequent characters in the format - string, up to and including the matching right bracket (]). The characters - between the brackets (the scanlist) compose the scanset, unless the character - after the left bracket is a circumflex (^), in which case the scanset contains all - characters that do not appear in the scanlist between the circumflex and the - right bracket. If the conversion specifier begins with [] or [^], the right - bracket character is in the scanlist and the next following right bracket - character is the matching right bracket that ends the specification; otherwise - the first following right bracket character is the one that ends the - specification. If a - character is in the scanlist and is not the first, nor the - second where the first character is a ^, nor the last character, the behavior is - implementation-defined. - p Matches an implementation-defined set of sequences, which should be the - same as the set of sequences that may be produced by the %p conversion of - the fprintf function. The corresponding argument shall be a pointer to a - pointer to void. The input item is converted to a pointer value in an - implementation-defined manner. If the input item is a value converted earlier - during the same program execution, the pointer that results shall compare - equal to that value; otherwise the behavior of the %p conversion is undefined. - n No input is consumed. The corresponding argument shall be a pointer to - signed integer into which is to be written the number of characters read from - the input stream so far by this call to the fscanf function. Execution of a - %n directive does not increment the assignment count returned at the - completion of execution of the fscanf function. No argument is converted, - but one is consumed. If the conversion specification includes an assignment- - suppressing character or a field width, the behavior is undefined. - % Matches a single % character; no conversion or assignment occurs. The - complete conversion specification shall be %%. -13 If a conversion specification is invalid, the behavior is undefined.276) -14 The conversion specifiers A, E, F, G, and X are also valid and behave the same as, - respectively, a, e, f, g, and x. - - - - 276) See ''future library directions'' (7.30.9). - -[page 320] - -15 Trailing white space (including new-line characters) is left unread unless matched by a - directive. The success of literal matches and suppressed assignments is not directly - determinable other than via the %n directive. - Returns -16 The fscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the function returns the - number of input items assigned, which can be fewer than provided for, or even zero, in - the event of an early matching failure. -17 EXAMPLE 1 The call: - #include - /* ... */ - int n, i; float x; char name[50]; - n = fscanf(stdin, "%d%f%s", &i, &x, name); - with the input line: - 25 54.32E-1 thompson - will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence - thompson\0. - -18 EXAMPLE 2 The call: - #include - /* ... */ - int i; float x; char name[50]; - fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name); - with input: - 56789 0123 56a72 - will assign to i the value 56 and to x the value 789.0, will skip 0123, and will assign to name the - sequence 56\0. The next character read from the input stream will be a. - -19 EXAMPLE 3 To accept repeatedly from stdin a quantity, a unit of measure, and an item name: - #include - /* ... */ - int count; float quant; char units[21], item[21]; - do { - count = fscanf(stdin, "%f%20s of %20s", &quant, units, item); - fscanf(stdin,"%*[^\n]"); - } while (!feof(stdin) && !ferror(stdin)); -20 If the stdin stream contains the following lines: - 2 quarts of oil - -12.8degrees Celsius - lots of luck - 10.0LBS of - dirt - 100ergs of energy - -[page 321] - - the execution of the above example will be analogous to the following assignments: - quant = 2; strcpy(units, "quarts"); strcpy(item, "oil"); - count = 3; - quant = -12.8; strcpy(units, "degrees"); - count = 2; // "C" fails to match "o" - count = 0; // "l" fails to match "%f" - quant = 10.0; strcpy(units, "LBS"); strcpy(item, "dirt"); - count = 3; - count = 0; // "100e" fails to match "%f" - count = EOF; - -21 EXAMPLE 4 In: - #include - /* ... */ - int d1, d2, n1, n2, i; - i = sscanf("123", "%d%n%n%d", &d1, &n1, &n2, &d2); - the value 123 is assigned to d1 and the value 3 to n1. Because %n can never get an input failure the value - of 3 is also assigned to n2. The value of d2 is not affected. The value 1 is assigned to i. - -22 EXAMPLE 5 In these examples, multibyte characters do have a state-dependent encoding, and the - members of the extended character set that consist of more than one byte each consist of exactly two bytes, - the first of which is denoted here by a and the second by an uppercase letter, but are only recognized as - such when in the alternate shift state. The shift sequences are denoted by (uparrow) and (downarrow), in which the first causes - entry into the alternate shift state. -23 After the call: - #include - /* ... */ - char str[50]; - fscanf(stdin, "a%s", str); - with the input line: - a(uparrow) X Y(downarrow) bc - str will contain (uparrow) X Y(downarrow)\0 assuming that none of the bytes of the shift sequences (or of the multibyte - characters, in the more general case) appears to be a single-byte white-space character. -24 In contrast, after the call: - #include - #include - /* ... */ - wchar_t wstr[50]; - fscanf(stdin, "a%ls", wstr); - with the same input line, wstr will contain the two wide characters that correspond to X and Y and a - terminating null wide character. -25 However, the call: - - - - -[page 322] - - #include - #include - /* ... */ - wchar_t wstr[50]; - fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr); - with the same input line will return zero due to a matching failure against the (downarrow) sequence in the format - string. -26 Assuming that the first byte of the multibyte character X is the same as the first byte of the multibyte - character Y, after the call: - #include - #include - /* ... */ - wchar_t wstr[50]; - fscanf(stdin, "a(uparrow) Y(downarrow)%ls", wstr); - with the same input line, zero will again be returned, but stdin will be left with a partially consumed - multibyte character. - - Forward references: the strtod, strtof, and strtold functions (7.22.1.3), the - strtol, strtoll, strtoul, and strtoull functions (7.22.1.4), conversion state - (7.28.6), the wcrtomb function (7.28.6.3.3). - 7.21.6.3 The printf function - Synopsis -1 #include - int printf(const char * restrict format, ...); - Description -2 The printf function is equivalent to fprintf with the argument stdout interposed - before the arguments to printf. - Returns -3 The printf function returns the number of characters transmitted, or a negative value if - an output or encoding error occurred. - 7.21.6.4 The scanf function - Synopsis -1 #include - int scanf(const char * restrict format, ...); - Description -2 The scanf function is equivalent to fscanf with the argument stdin interposed - before the arguments to scanf. - - - -[page 323] - - Returns -3 The scanf function returns the value of the macro EOF if an input failure occurs before - the first conversion (if any) has completed. Otherwise, the scanf function returns the - number of input items assigned, which can be fewer than provided for, or even zero, in - the event of an early matching failure. - 7.21.6.5 The snprintf function - Synopsis -1 #include - int snprintf(char * restrict s, size_t n, - const char * restrict format, ...); - Description -2 The snprintf function is equivalent to fprintf, except that the output is written into - an array (specified by argument s) rather than to a stream. If n is zero, nothing is written, - and s may be a null pointer. Otherwise, output characters beyond the n-1st are - discarded rather than being written to the array, and a null character is written at the end - of the characters actually written into the array. If copying takes place between objects - that overlap, the behavior is undefined. - Returns -3 The snprintf function returns the number of characters that would have been written - had n been sufficiently large, not counting the terminating null character, or a negative - value if an encoding error occurred. Thus, the null-terminated output has been - completely written if and only if the returned value is nonnegative and less than n. - 7.21.6.6 The sprintf function - Synopsis -1 #include - int sprintf(char * restrict s, - const char * restrict format, ...); - Description -2 The sprintf function is equivalent to fprintf, except that the output is written into - an array (specified by the argument s) rather than to a stream. A null character is written - at the end of the characters written; it is not counted as part of the returned value. If - copying takes place between objects that overlap, the behavior is undefined. - Returns -3 The sprintf function returns the number of characters written in the array, not - counting the terminating null character, or a negative value if an encoding error occurred. - -[page 324] - - 7.21.6.7 The sscanf function - Synopsis -1 #include - int sscanf(const char * restrict s, - const char * restrict format, ...); - Description -2 The sscanf function is equivalent to fscanf, except that input is obtained from a - string (specified by the argument s) rather than from a stream. Reaching the end of the - string is equivalent to encountering end-of-file for the fscanf function. If copying - takes place between objects that overlap, the behavior is undefined. - Returns -3 The sscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the sscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.21.6.8 The vfprintf function - Synopsis -1 #include - #include - int vfprintf(FILE * restrict stream, - const char * restrict format, - va_list arg); - Description -2 The vfprintf function is equivalent to fprintf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vfprintf function does not invoke the - va_end macro.277) - Returns -3 The vfprintf function returns the number of characters transmitted, or a negative - value if an output or encoding error occurred. -4 EXAMPLE The following shows the use of the vfprintf function in a general error-reporting routine. - - - - - 277) As the functions vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf, and - vsscanf invoke the va_arg macro, the value of arg after the return is indeterminate. - -[page 325] - - #include - #include - void error(char *function_name, char *format, ...) - { - va_list args; - va_start(args, format); - // print out name of function causing error - fprintf(stderr, "ERROR in %s: ", function_name); - // print out remainder of message - vfprintf(stderr, format, args); - va_end(args); - } - - 7.21.6.9 The vfscanf function - Synopsis -1 #include - #include - int vfscanf(FILE * restrict stream, - const char * restrict format, - va_list arg); - Description -2 The vfscanf function is equivalent to fscanf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vfscanf function does not invoke the - va_end macro.277) - Returns -3 The vfscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the vfscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.21.6.10 The vprintf function - Synopsis -1 #include - #include - int vprintf(const char * restrict format, - va_list arg); - Description -2 The vprintf function is equivalent to printf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - -[page 326] - - possibly subsequent va_arg calls). The vprintf function does not invoke the - va_end macro.277) - Returns -3 The vprintf function returns the number of characters transmitted, or a negative value - if an output or encoding error occurred. - 7.21.6.11 The vscanf function - Synopsis -1 #include - #include - int vscanf(const char * restrict format, - va_list arg); - Description -2 The vscanf function is equivalent to scanf, with the variable argument list replaced - by arg, which shall have been initialized by the va_start macro (and possibly - subsequent va_arg calls). The vscanf function does not invoke the va_end - macro.277) - Returns -3 The vscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the vscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.21.6.12 The vsnprintf function - Synopsis -1 #include - #include - int vsnprintf(char * restrict s, size_t n, - const char * restrict format, - va_list arg); - Description -2 The vsnprintf function is equivalent to snprintf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vsnprintf function does not invoke the - va_end macro.277) If copying takes place between objects that overlap, the behavior is - undefined. - - - -[page 327] - - Returns -3 The vsnprintf function returns the number of characters that would have been written - had n been sufficiently large, not counting the terminating null character, or a negative - value if an encoding error occurred. Thus, the null-terminated output has been - completely written if and only if the returned value is nonnegative and less than n. - 7.21.6.13 The vsprintf function - Synopsis -1 #include - #include - int vsprintf(char * restrict s, - const char * restrict format, - va_list arg); - Description -2 The vsprintf function is equivalent to sprintf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vsprintf function does not invoke the - va_end macro.277) If copying takes place between objects that overlap, the behavior is - undefined. - Returns -3 The vsprintf function returns the number of characters written in the array, not - counting the terminating null character, or a negative value if an encoding error occurred. - 7.21.6.14 The vsscanf function - Synopsis -1 #include - #include - int vsscanf(const char * restrict s, - const char * restrict format, - va_list arg); - Description -2 The vsscanf function is equivalent to sscanf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vsscanf function does not invoke the - va_end macro.277) - Returns -3 The vsscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the vsscanf function -[page 328] - - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.21.7 Character input/output functions - 7.21.7.1 The fgetc function - Synopsis -1 #include - int fgetc(FILE *stream); - Description -2 If the end-of-file indicator for the input stream pointed to by stream is not set and a - next character is present, the fgetc function obtains that character as an unsigned - char converted to an int and advances the associated file position indicator for the - stream (if defined). - Returns -3 If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end- - of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the - fgetc function returns the next character from the input stream pointed to by stream. - If a read error occurs, the error indicator for the stream is set and the fgetc function - returns EOF.278) - 7.21.7.2 The fgets function - Synopsis -1 #include - char *fgets(char * restrict s, int n, - FILE * restrict stream); - Description -2 The fgets function reads at most one less than the number of characters specified by n - from the stream pointed to by stream into the array pointed to by s. No additional - characters are read after a new-line character (which is retained) or after end-of-file. A - null character is written immediately after the last character read into the array. - Returns -3 The fgets function returns s if successful. If end-of-file is encountered and no - characters have been read into the array, the contents of the array remain unchanged and a - null pointer is returned. If a read error occurs during the operation, the array contents are - indeterminate and a null pointer is returned. - - 278) An end-of-file and a read error can be distinguished by use of the feof and ferror functions. - -[page 329] - - 7.21.7.3 The fputc function - Synopsis -1 #include - int fputc(int c, FILE *stream); - Description -2 The fputc function writes the character specified by c (converted to an unsigned - char) to the output stream pointed to by stream, at the position indicated by the - associated file position indicator for the stream (if defined), and advances the indicator - appropriately. If the file cannot support positioning requests, or if the stream was opened - with append mode, the character is appended to the output stream. - Returns -3 The fputc function returns the character written. If a write error occurs, the error - indicator for the stream is set and fputc returns EOF. - 7.21.7.4 The fputs function - Synopsis -1 #include - int fputs(const char * restrict s, - FILE * restrict stream); - Description -2 The fputs function writes the string pointed to by s to the stream pointed to by - stream. The terminating null character is not written. - Returns -3 The fputs function returns EOF if a write error occurs; otherwise it returns a - nonnegative value. - 7.21.7.5 The getc function - Synopsis -1 #include - int getc(FILE *stream); - Description -2 The getc function is equivalent to fgetc, except that if it is implemented as a macro, it - may evaluate stream more than once, so the argument should never be an expression - with side effects. - - - - -[page 330] - - Returns -3 The getc function returns the next character from the input stream pointed to by - stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and - getc returns EOF. If a read error occurs, the error indicator for the stream is set and - getc returns EOF. - 7.21.7.6 The getchar function - Synopsis -1 #include - int getchar(void); - Description -2 The getchar function is equivalent to getc with the argument stdin. - Returns -3 The getchar function returns the next character from the input stream pointed to by - stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and - getchar returns EOF. If a read error occurs, the error indicator for the stream is set and - getchar returns EOF. - 7.21.7.7 The putc function - Synopsis -1 #include - int putc(int c, FILE *stream); - Description -2 The putc function is equivalent to fputc, except that if it is implemented as a macro, it - may evaluate stream more than once, so that argument should never be an expression - with side effects. - Returns -3 The putc function returns the character written. If a write error occurs, the error - indicator for the stream is set and putc returns EOF. - 7.21.7.8 The putchar function - Synopsis -1 #include - int putchar(int c); - Description -2 The putchar function is equivalent to putc with the second argument stdout. - - -[page 331] - - Returns -3 The putchar function returns the character written. If a write error occurs, the error - indicator for the stream is set and putchar returns EOF. - 7.21.7.9 The puts function - Synopsis -1 #include - int puts(const char *s); - Description -2 The puts function writes the string pointed to by s to the stream pointed to by stdout, - and appends a new-line character to the output. The terminating null character is not - written. - Returns -3 The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative - value. - 7.21.7.10 The ungetc function - Synopsis -1 #include - int ungetc(int c, FILE *stream); - Description -2 The ungetc function pushes the character specified by c (converted to an unsigned - char) back onto the input stream pointed to by stream. Pushed-back characters will be - returned by subsequent reads on that stream in the reverse order of their pushing. A - successful intervening call (with the stream pointed to by stream) to a file positioning - function (fseek, fsetpos, or rewind) discards any pushed-back characters for the - stream. The external storage corresponding to the stream is unchanged. -3 One character of pushback is guaranteed. If the ungetc function is called too many - times on the same stream without an intervening read or file positioning operation on that - stream, the operation may fail. -4 If the value of c equals that of the macro EOF, the operation fails and the input stream is - unchanged. -5 A successful call to the ungetc function clears the end-of-file indicator for the stream. - The value of the file position indicator for the stream after reading or discarding all - pushed-back characters shall be the same as it was before the characters were pushed - back. For a text stream, the value of its file position indicator after a successful call to the - ungetc function is unspecified until all pushed-back characters are read or discarded. - -[page 332] - - For a binary stream, its file position indicator is decremented by each successful call to - the ungetc function; if its value was zero before a call, it is indeterminate after the - call.279) - Returns -6 The ungetc function returns the character pushed back after conversion, or EOF if the - operation fails. - Forward references: file positioning functions (7.21.9). - 7.21.8 Direct input/output functions - 7.21.8.1 The fread function - Synopsis -1 #include - size_t fread(void * restrict ptr, - size_t size, size_t nmemb, - FILE * restrict stream); - Description -2 The fread function reads, into the array pointed to by ptr, up to nmemb elements - whose size is specified by size, from the stream pointed to by stream. For each - object, size calls are made to the fgetc function and the results stored, in the order - read, in an array of unsigned char exactly overlaying the object. The file position - indicator for the stream (if defined) is advanced by the number of characters successfully - read. If an error occurs, the resulting value of the file position indicator for the stream is - indeterminate. If a partial element is read, its value is indeterminate. - Returns -3 The fread function returns the number of elements successfully read, which may be - less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero, - fread returns zero and the contents of the array and the state of the stream remain - unchanged. - - - - - 279) See ''future library directions'' (7.30.9). - -[page 333] - - 7.21.8.2 The fwrite function - Synopsis -1 #include - size_t fwrite(const void * restrict ptr, - size_t size, size_t nmemb, - FILE * restrict stream); - Description -2 The fwrite function writes, from the array pointed to by ptr, up to nmemb elements - whose size is specified by size, to the stream pointed to by stream. For each object, - size calls are made to the fputc function, taking the values (in order) from an array of - unsigned char exactly overlaying the object. The file position indicator for the - stream (if defined) is advanced by the number of characters successfully written. If an - error occurs, the resulting value of the file position indicator for the stream is - indeterminate. - Returns -3 The fwrite function returns the number of elements successfully written, which will be - less than nmemb only if a write error is encountered. If size or nmemb is zero, - fwrite returns zero and the state of the stream remains unchanged. - 7.21.9 File positioning functions - 7.21.9.1 The fgetpos function - Synopsis -1 #include - int fgetpos(FILE * restrict stream, - fpos_t * restrict pos); - Description -2 The fgetpos function stores the current values of the parse state (if any) and file - position indicator for the stream pointed to by stream in the object pointed to by pos. - The values stored contain unspecified information usable by the fsetpos function for - repositioning the stream to its position at the time of the call to the fgetpos function. - Returns -3 If successful, the fgetpos function returns zero; on failure, the fgetpos function - returns nonzero and stores an implementation-defined positive value in errno. - Forward references: the fsetpos function (7.21.9.3). - - - - -[page 334] - - 7.21.9.2 The fseek function - Synopsis -1 #include - int fseek(FILE *stream, long int offset, int whence); - Description -2 The fseek function sets the file position indicator for the stream pointed to by stream. - If a read or write error occurs, the error indicator for the stream is set and fseek fails. -3 For a binary stream, the new position, measured in characters from the beginning of the - file, is obtained by adding offset to the position specified by whence. The specified - position is the beginning of the file if whence is SEEK_SET, the current value of the file - position indicator if SEEK_CUR, or end-of-file if SEEK_END. A binary stream need not - meaningfully support fseek calls with a whence value of SEEK_END. -4 For a text stream, either offset shall be zero, or offset shall be a value returned by - an earlier successful call to the ftell function on a stream associated with the same file - and whence shall be SEEK_SET. -5 After determining the new position, a successful call to the fseek function undoes any - effects of the ungetc function on the stream, clears the end-of-file indicator for the - stream, and then establishes the new position. After a successful fseek call, the next - operation on an update stream may be either input or output. - Returns -6 The fseek function returns nonzero only for a request that cannot be satisfied. - Forward references: the ftell function (7.21.9.4). - 7.21.9.3 The fsetpos function - Synopsis -1 #include - int fsetpos(FILE *stream, const fpos_t *pos); - Description -2 The fsetpos function sets the mbstate_t object (if any) and file position indicator - for the stream pointed to by stream according to the value of the object pointed to by - pos, which shall be a value obtained from an earlier successful call to the fgetpos - function on a stream associated with the same file. If a read or write error occurs, the - error indicator for the stream is set and fsetpos fails. -3 A successful call to the fsetpos function undoes any effects of the ungetc function - on the stream, clears the end-of-file indicator for the stream, and then establishes the new - parse state and position. After a successful fsetpos call, the next operation on an - -[page 335] - - update stream may be either input or output. - Returns -4 If successful, the fsetpos function returns zero; on failure, the fsetpos function - returns nonzero and stores an implementation-defined positive value in errno. - 7.21.9.4 The ftell function - Synopsis -1 #include - long int ftell(FILE *stream); - Description -2 The ftell function obtains the current value of the file position indicator for the stream - pointed to by stream. For a binary stream, the value is the number of characters from - the beginning of the file. For a text stream, its file position indicator contains unspecified - information, usable by the fseek function for returning the file position indicator for the - stream to its position at the time of the ftell call; the difference between two such - return values is not necessarily a meaningful measure of the number of characters written - or read. - Returns -3 If successful, the ftell function returns the current value of the file position indicator - for the stream. On failure, the ftell function returns -1L and stores an - implementation-defined positive value in errno. - 7.21.9.5 The rewind function - Synopsis -1 #include - void rewind(FILE *stream); - Description -2 The rewind function sets the file position indicator for the stream pointed to by - stream to the beginning of the file. It is equivalent to - (void)fseek(stream, 0L, SEEK_SET) - except that the error indicator for the stream is also cleared. - Returns -3 The rewind function returns no value. - - - - -[page 336] - - 7.21.10 Error-handling functions - 7.21.10.1 The clearerr function - Synopsis -1 #include - void clearerr(FILE *stream); - Description -2 The clearerr function clears the end-of-file and error indicators for the stream pointed - to by stream. - Returns -3 The clearerr function returns no value. - 7.21.10.2 The feof function - Synopsis -1 #include - int feof(FILE *stream); - Description -2 The feof function tests the end-of-file indicator for the stream pointed to by stream. - Returns -3 The feof function returns nonzero if and only if the end-of-file indicator is set for - stream. - 7.21.10.3 The ferror function - Synopsis -1 #include - int ferror(FILE *stream); - Description -2 The ferror function tests the error indicator for the stream pointed to by stream. - Returns -3 The ferror function returns nonzero if and only if the error indicator is set for - stream. - - - - -[page 337] - - 7.21.10.4 The perror function - Synopsis -1 #include - void perror(const char *s); - Description -2 The perror function maps the error number in the integer expression errno to an - error message. It writes a sequence of characters to the standard error stream thus: first - (if s is not a null pointer and the character pointed to by s is not the null character), the - string pointed to by s followed by a colon (:) and a space; then an appropriate error - message string followed by a new-line character. The contents of the error message - strings are the same as those returned by the strerror function with argument errno. - Returns -3 The perror function returns no value. - Forward references: the strerror function (7.23.6.2). - - - - -[page 338] - - 7.22 General utilities -1 The header declares five types and several functions of general utility, and - defines several macros.280) -2 The types declared are size_t and wchar_t (both described in 7.19), - div_t - which is a structure type that is the type of the value returned by the div function, - ldiv_t - which is a structure type that is the type of the value returned by the ldiv function, and - lldiv_t - which is a structure type that is the type of the value returned by the lldiv function. -3 The macros defined are NULL (described in 7.19); - EXIT_FAILURE - and - EXIT_SUCCESS - which expand to integer constant expressions that can be used as the argument to the - exit function to return unsuccessful or successful termination status, respectively, to the - host environment; - RAND_MAX - which expands to an integer constant expression that is the maximum value returned by - the rand function; and - MB_CUR_MAX - which expands to a positive integer expression with type size_t that is the maximum - number of bytes in a multibyte character for the extended character set specified by the - current locale (category LC_CTYPE), which is never greater than MB_LEN_MAX. - - - - - 280) See ''future library directions'' (7.30.10). - -[page 339] - - 7.22.1 Numeric conversion functions -1 The functions atof, atoi, atol, and atoll need not affect the value of the integer - expression errno on an error. If the value of the result cannot be represented, the - behavior is undefined. - 7.22.1.1 The atof function - Synopsis -1 #include - double atof(const char *nptr); - Description -2 The atof function converts the initial portion of the string pointed to by nptr to - double representation. Except for the behavior on error, it is equivalent to - strtod(nptr, (char **)NULL) - Returns -3 The atof function returns the converted value. - Forward references: the strtod, strtof, and strtold functions (7.22.1.3). - 7.22.1.2 The atoi, atol, and atoll functions - Synopsis -1 #include - int atoi(const char *nptr); - long int atol(const char *nptr); - long long int atoll(const char *nptr); - Description -2 The atoi, atol, and atoll functions convert the initial portion of the string pointed - to by nptr to int, long int, and long long int representation, respectively. - Except for the behavior on error, they are equivalent to - atoi: (int)strtol(nptr, (char **)NULL, 10) - atol: strtol(nptr, (char **)NULL, 10) - atoll: strtoll(nptr, (char **)NULL, 10) - Returns -3 The atoi, atol, and atoll functions return the converted value. - Forward references: the strtol, strtoll, strtoul, and strtoull functions - (7.22.1.4). - - - -[page 340] - - 7.22.1.3 The strtod, strtof, and strtold functions - Synopsis -1 #include - double strtod(const char * restrict nptr, - char ** restrict endptr); - float strtof(const char * restrict nptr, - char ** restrict endptr); - long double strtold(const char * restrict nptr, - char ** restrict endptr); - Description -2 The strtod, strtof, and strtold functions convert the initial portion of the string - pointed to by nptr to double, float, and long double representation, - respectively. First, they decompose the input string into three parts: an initial, possibly - empty, sequence of white-space characters (as specified by the isspace function), a - subject sequence resembling a floating-point constant or representing an infinity or NaN; - and a final string of one or more unrecognized characters, including the terminating null - character of the input string. Then, they attempt to convert the subject sequence to a - floating-point number, and return the result. -3 The expected form of the subject sequence is an optional plus or minus sign, then one of - the following: - -- a nonempty sequence of decimal digits optionally containing a decimal-point - character, then an optional exponent part as defined in 6.4.4.2; - -- a 0x or 0X, then a nonempty sequence of hexadecimal digits optionally containing a - decimal-point character, then an optional binary exponent part as defined in 6.4.4.2; - -- INF or INFINITY, ignoring case - -- NAN or NAN(n-char-sequenceopt), ignoring case in the NAN part, where: - n-char-sequence: - digit - nondigit - n-char-sequence digit - n-char-sequence nondigit - The subject sequence is defined as the longest initial subsequence of the input string, - starting with the first non-white-space character, that is of the expected form. The subject - sequence contains no characters if the input string is not of the expected form. -4 If the subject sequence has the expected form for a floating-point number, the sequence of - characters starting with the first digit or the decimal-point character (whichever occurs - first) is interpreted as a floating constant according to the rules of 6.4.4.2, except that the -[page 341] - - decimal-point character is used in place of a period, and that if neither an exponent part - nor a decimal-point character appears in a decimal floating point number, or if a binary - exponent part does not appear in a hexadecimal floating point number, an exponent part - of the appropriate type with value zero is assumed to follow the last digit in the string. If - the subject sequence begins with a minus sign, the sequence is interpreted as negated.281) - A character sequence INF or INFINITY is interpreted as an infinity, if representable in - the return type, else like a floating constant that is too large for the range of the return - type. A character sequence NAN or NAN(n-char-sequenceopt), is interpreted as a quiet - NaN, if supported in the return type, else like a subject sequence part that does not have - the expected form; the meaning of the n-char sequences is implementation-defined.282) A - pointer to the final string is stored in the object pointed to by endptr, provided that - endptr is not a null pointer. -5 If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the - value resulting from the conversion is correctly rounded. -6 In other than the "C" locale, additional locale-specific subject sequence forms may be - accepted. -7 If the subject sequence is empty or does not have the expected form, no conversion is - performed; the value of nptr is stored in the object pointed to by endptr, provided - that endptr is not a null pointer. - Recommended practice -8 If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and - the result is not exactly representable, the result should be one of the two numbers in the - appropriate internal format that are adjacent to the hexadecimal floating source value, - with the extra stipulation that the error should have a correct sign for the current rounding - direction. -9 If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in - ) significant digits, the result should be correctly rounded. If the subject - sequence D has the decimal form and more than DECIMAL_DIG significant digits, - consider the two bounding, adjacent decimal strings L and U, both having - DECIMAL_DIG significant digits, such that the values of L, D, and U satisfy L <= D <= U. - The result should be one of the (equal or adjacent) values that would be obtained by - correctly rounding L and U according to the current rounding direction, with the extra - - 281) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by - negating the value resulting from converting the corresponding unsigned sequence (see F.5); the two - methods may yield different results if rounding is toward positive or negative infinity. In either case, - the functions honor the sign of zero if floating-point arithmetic supports signed zeros. - 282) An implementation may use the n-char sequence to determine extra information to be represented in - the NaN's significand. - -[page 342] - - stipulation that the error with respect to D should have a correct sign for the current - rounding direction.283) - Returns -10 The functions return the converted value, if any. If no conversion could be performed, - zero is returned. If the correct value overflows and default rounding is in effect (7.12.1), - plus or minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the - return type and sign of the value), and the value of the macro ERANGE is stored in - errno. If the result underflows (7.12.1), the functions return a value whose magnitude is - no greater than the smallest normalized positive number in the return type; whether - errno acquires the value ERANGE is implementation-defined. - 7.22.1.4 The strtol, strtoll, strtoul, and strtoull functions - Synopsis -1 #include - long int strtol( - const char * restrict nptr, - char ** restrict endptr, - int base); - long long int strtoll( - const char * restrict nptr, - char ** restrict endptr, - int base); - unsigned long int strtoul( - const char * restrict nptr, - char ** restrict endptr, - int base); - unsigned long long int strtoull( - const char * restrict nptr, - char ** restrict endptr, - int base); - Description -2 The strtol, strtoll, strtoul, and strtoull functions convert the initial - portion of the string pointed to by nptr to long int, long long int, unsigned - long int, and unsigned long long int representation, respectively. First, - they decompose the input string into three parts: an initial, possibly empty, sequence of - white-space characters (as specified by the isspace function), a subject sequence - - - 283) DECIMAL_DIG, defined in , should be sufficiently large that L and U will usually round - to the same internal floating value, but if not will round to adjacent values. - -[page 343] - - resembling an integer represented in some radix determined by the value of base, and a - final string of one or more unrecognized characters, including the terminating null - character of the input string. Then, they attempt to convert the subject sequence to an - integer, and return the result. -3 If the value of base is zero, the expected form of the subject sequence is that of an - integer constant as described in 6.4.4.1, optionally preceded by a plus or minus sign, but - not including an integer suffix. If the value of base is between 2 and 36 (inclusive), the - expected form of the subject sequence is a sequence of letters and digits representing an - integer with the radix specified by base, optionally preceded by a plus or minus sign, - but not including an integer suffix. The letters from a (or A) through z (or Z) are - ascribed the values 10 through 35; only letters and digits whose ascribed values are less - than that of base are permitted. If the value of base is 16, the characters 0x or 0X may - optionally precede the sequence of letters and digits, following the sign if present. -4 The subject sequence is defined as the longest initial subsequence of the input string, - starting with the first non-white-space character, that is of the expected form. The subject - sequence contains no characters if the input string is empty or consists entirely of white - space, or if the first non-white-space character is other than a sign or a permissible letter - or digit. -5 If the subject sequence has the expected form and the value of base is zero, the sequence - of characters starting with the first digit is interpreted as an integer constant according to - the rules of 6.4.4.1. If the subject sequence has the expected form and the value of base - is between 2 and 36, it is used as the base for conversion, ascribing to each letter its value - as given above. If the subject sequence begins with a minus sign, the value resulting from - the conversion is negated (in the return type). A pointer to the final string is stored in the - object pointed to by endptr, provided that endptr is not a null pointer. -6 In other than the "C" locale, additional locale-specific subject sequence forms may be - accepted. -7 If the subject sequence is empty or does not have the expected form, no conversion is - performed; the value of nptr is stored in the object pointed to by endptr, provided - that endptr is not a null pointer. - Returns -8 The strtol, strtoll, strtoul, and strtoull functions return the converted - value, if any. If no conversion could be performed, zero is returned. If the correct value - is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN, - LLONG_MAX, ULONG_MAX, or ULLONG_MAX is returned (according to the return type - and sign of the value, if any), and the value of the macro ERANGE is stored in errno. - - - - -[page 344] - - 7.22.2 Pseudo-random sequence generation functions - 7.22.2.1 The rand function - Synopsis -1 #include - int rand(void); - Description -2 The rand function computes a sequence of pseudo-random integers in the range 0 to - RAND_MAX.284) -3 The rand function is not required to avoid data races. The implementation shall behave - as if no library function calls the rand function. - Returns -4 The rand function returns a pseudo-random integer. - Environmental limits -5 The value of the RAND_MAX macro shall be at least 32767. - 7.22.2.2 The srand function - Synopsis -1 #include - void srand(unsigned int seed); - Description -2 The srand function uses the argument as a seed for a new sequence of pseudo-random - numbers to be returned by subsequent calls to rand. If srand is then called with the - same seed value, the sequence of pseudo-random numbers shall be repeated. If rand is - called before any calls to srand have been made, the same sequence shall be generated - as when srand is first called with a seed value of 1. -3 The implementation shall behave as if no library function calls the srand function. - Returns -4 The srand function returns no value. - - - - - 284) There are no guarantees as to the quality of the random sequence produced and some implementations - are known to produce sequences with distressingly non-random low-order bits. Applications with - particular requirements should use a generator that is known to be sufficient for their needs. - -[page 345] - -5 EXAMPLE The following functions define a portable implementation of rand and srand. - static unsigned long int next = 1; - int rand(void) // RAND_MAX assumed to be 32767 - { - next = next * 1103515245 + 12345; - return (unsigned int)(next/65536) % 32768; - } - void srand(unsigned int seed) - { - next = seed; - } - - 7.22.3 Memory management functions -1 The order and contiguity of storage allocated by successive calls to the - aligned_alloc, calloc, malloc, and realloc functions is unspecified. The - pointer returned if the allocation succeeds is suitably aligned so that it may be assigned to - a pointer to any type of object with a fundamental alignment requirement and then used - to access such an object or an array of such objects in the space allocated (until the space - is explicitly deallocated). The lifetime of an allocated object extends from the allocation - until the deallocation. Each such allocation shall yield a pointer to an object disjoint from - any other object. The pointer returned points to the start (lowest byte address) of the - allocated space. If the space cannot be allocated, a null pointer is returned. If the size of - the space requested is zero, the behavior is implementation-defined: either a null pointer - is returned, or the behavior is as if the size were some nonzero value, except that the - returned pointer shall not be used to access an object. - 7.22.3.1 The aligned_alloc function - Synopsis -1 #include - void *aligned_alloc(size_t alignment, size_t size); - Description -2 The aligned_alloc function allocates space for an object whose alignment is - specified by alignment, whose size is specified by size, and whose value is - indeterminate. The value of alignment shall be a valid alignment supported by the - implementation and the value of size shall be an integral multiple of alignment. - Returns -3 The aligned_alloc function returns either a null pointer or a pointer to the allocated - space. - - - - -[page 346] - - 7.22.3.2 The calloc function - Synopsis -1 #include - void *calloc(size_t nmemb, size_t size); - Description -2 The calloc function allocates space for an array of nmemb objects, each of whose size - is size. The space is initialized to all bits zero.285) - Returns -3 The calloc function returns either a null pointer or a pointer to the allocated space. - 7.22.3.3 The free function - Synopsis -1 #include - void free(void *ptr); - Description -2 The free function causes the space pointed to by ptr to be deallocated, that is, made - available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if - the argument does not match a pointer earlier returned by a memory management - function, or if the space has been deallocated by a call to free or realloc, the - behavior is undefined. - Returns -3 The free function returns no value. - 7.22.3.4 The malloc function - Synopsis -1 #include - void *malloc(size_t size); - Description -2 The malloc function allocates space for an object whose size is specified by size and - whose value is indeterminate. - - - - - 285) Note that this need not be the same as the representation of floating-point zero or a null pointer - constant. - -[page 347] - - Returns -3 The malloc function returns either a null pointer or a pointer to the allocated space. - 7.22.3.5 The realloc function - Synopsis -1 #include - void *realloc(void *ptr, size_t size); - Description -2 The realloc function deallocates the old object pointed to by ptr and returns a - pointer to a new object that has the size specified by size. The contents of the new - object shall be the same as that of the old object prior to deallocation, up to the lesser of - the new and old sizes. Any bytes in the new object beyond the size of the old object have - indeterminate values. -3 If ptr is a null pointer, the realloc function behaves like the malloc function for the - specified size. Otherwise, if ptr does not match a pointer earlier returned by a memory - management function, or if the space has been deallocated by a call to the free or - realloc function, the behavior is undefined. If memory for the new object cannot be - allocated, the old object is not deallocated and its value is unchanged. - Returns -4 The realloc function returns a pointer to the new object (which may have the same - value as a pointer to the old object), or a null pointer if the new object could not be - allocated. - 7.22.4 Communication with the environment - 7.22.4.1 The abort function - Synopsis -1 #include - _Noreturn void abort(void); - Description -2 The abort function causes abnormal program termination to occur, unless the signal - SIGABRT is being caught and the signal handler does not return. Whether open streams - with unwritten buffered data are flushed, open streams are closed, or temporary files are - removed is implementation-defined. An implementation-defined form of the status - unsuccessful termination is returned to the host environment by means of the function - call raise(SIGABRT). - - - - -[page 348] - - Returns -3 The abort function does not return to its caller. - 7.22.4.2 The atexit function - Synopsis -1 #include - int atexit(void (*func)(void)); - Description -2 The atexit function registers the function pointed to by func, to be called without - arguments at normal program termination.286) - Environmental limits -3 The implementation shall support the registration of at least 32 functions. - Returns -4 The atexit function returns zero if the registration succeeds, nonzero if it fails. - Forward references: the at_quick_exit function (7.22.4.3), the exit function - (7.22.4.4). - 7.22.4.3 The at_quick_exit function - Synopsis -1 #include - int at_quick_exit(void (*func)(void)); - Description -2 The at_quick_exit function registers the function pointed to by func, to be called - without arguments should quick_exit be called.287) - Environmental limits -3 The implementation shall support the registration of at least 32 functions. - Returns -4 The at_quick_exit function returns zero if the registration succeeds, nonzero if it - fails. - Forward references: the quick_exit function (7.22.4.7). - - 286) The atexit function registrations are distinct from the at_quick_exit registrations, so - applications may need to call both registration functions with the same argument. - 287) The at_quick_exit function registrations are distinct from the atexit registrations, so - applications may need to call both registration functions with the same argument. - -[page 349] - - 7.22.4.4 The exit function - Synopsis -1 #include - _Noreturn void exit(int status); - Description -2 The exit function causes normal program termination to occur. No functions registered - by the at_quick_exit function are called. If a program calls the exit function - more than once, or calls the quick_exit function in addition to the exit function, the - behavior is undefined. -3 First, all functions registered by the atexit function are called, in the reverse order of - their registration,288) except that a function is called after any previously registered - functions that had already been called at the time it was registered. If, during the call to - any such function, a call to the longjmp function is made that would terminate the call - to the registered function, the behavior is undefined. -4 Next, all open streams with unwritten buffered data are flushed, all open streams are - closed, and all files created by the tmpfile function are removed. -5 Finally, control is returned to the host environment. If the value of status is zero or - EXIT_SUCCESS, an implementation-defined form of the status successful termination is - returned. If the value of status is EXIT_FAILURE, an implementation-defined form - of the status unsuccessful termination is returned. Otherwise the status returned is - implementation-defined. - Returns -6 The exit function cannot return to its caller. - 7.22.4.5 The _Exit function - Synopsis -1 #include - _Noreturn void _Exit(int status); - Description -2 The _Exit function causes normal program termination to occur and control to be - returned to the host environment. No functions registered by the atexit function, the - at_quick_exit function, or signal handlers registered by the signal function are - called. The status returned to the host environment is determined in the same way as for - - - 288) Each function is called as many times as it was registered, and in the correct order with respect to - other registered functions. - -[page 350] - - the exit function (7.22.4.4). Whether open streams with unwritten buffered data are - flushed, open streams are closed, or temporary files are removed is implementation- - defined. - Returns -3 The _Exit function cannot return to its caller. - 7.22.4.6 The getenv function - Synopsis -1 #include - char *getenv(const char *name); - Description -2 The getenv function searches an environment list, provided by the host environment, - for a string that matches the string pointed to by name. The set of environment names - and the method for altering the environment list are implementation-defined. The - getenv function need not avoid data races with other threads of execution that modify - the environment list.289) -3 The implementation shall behave as if no library function calls the getenv function. - Returns -4 The getenv function returns a pointer to a string associated with the matched list - member. The string pointed to shall not be modified by the program, but may be - overwritten by a subsequent call to the getenv function. If the specified name cannot - be found, a null pointer is returned. - 7.22.4.7 The quick_exit function - Synopsis -1 #include - _Noreturn void quick_exit(int status); - Description -2 The quick_exit function causes normal program termination to occur. No functions - registered by the atexit function or signal handlers registered by the signal function - are called. If a program calls the quick_exit function more than once, or calls the - exit function in addition to the quick_exit function, the behavior is undefined. -3 The quick_exit function first calls all functions registered by the at_quick_exit - function, in the reverse order of their registration,290) except that a function is called after - - - 289) Many implementations provide non-standard functions that modify the environment list. - -[page 351] - - any previously registered functions that had already been called at the time it was - registered. If, during the call to any such function, a call to the longjmp function is - made that would terminate the call to the registered function, the behavior is undefined. -4 Then control is returned to the host environment by means of the function call - _Exit(status). - Returns -5 The quick_exit function cannot return to its caller. - 7.22.4.8 The system function - Synopsis -1 #include - int system(const char *string); - Description -2 If string is a null pointer, the system function determines whether the host - environment has a command processor. If string is not a null pointer, the system - function passes the string pointed to by string to that command processor to be - executed in a manner which the implementation shall document; this might then cause the - program calling system to behave in a non-conforming manner or to terminate. - Returns -3 If the argument is a null pointer, the system function returns nonzero only if a - command processor is available. If the argument is not a null pointer, and the system - function does return, it returns an implementation-defined value. - 7.22.5 Searching and sorting utilities -1 These utilities make use of a comparison function to search or sort arrays of unspecified - type. Where an argument declared as size_t nmemb specifies the length of the array - for a function, nmemb can have the value zero on a call to that function; the comparison - function is not called, a search finds no matching element, and sorting performs no - rearrangement. Pointer arguments on such a call shall still have valid values, as described - in 7.1.4. -2 The implementation shall ensure that the second argument of the comparison function - (when called from bsearch), or both arguments (when called from qsort), are - pointers to elements of the array.291) The first argument when called from bsearch - shall equal key. - - - - 290) Each function is called as many times as it was registered, and in the correct order with respect to - other registered functions. - -[page 352] - -3 The comparison function shall not alter the contents of the array. The implementation - may reorder elements of the array between calls to the comparison function, but shall not - alter the contents of any individual element. -4 When the same objects (consisting of size bytes, irrespective of their current positions - in the array) are passed more than once to the comparison function, the results shall be - consistent with one another. That is, for qsort they shall define a total ordering on the - array, and for bsearch the same object shall always compare the same way with the - key. -5 A sequence point occurs immediately before and immediately after each call to the - comparison function, and also between any call to the comparison function and any - movement of the objects passed as arguments to that call. - 7.22.5.1 The bsearch function - Synopsis -1 #include - void *bsearch(const void *key, const void *base, - size_t nmemb, size_t size, - int (*compar)(const void *, const void *)); - Description -2 The bsearch function searches an array of nmemb objects, the initial element of which - is pointed to by base, for an element that matches the object pointed to by key. The - size of each element of the array is specified by size. -3 The comparison function pointed to by compar is called with two arguments that point - to the key object and to an array element, in that order. The function shall return an - integer less than, equal to, or greater than zero if the key object is considered, - respectively, to be less than, to match, or to be greater than the array element. The array - shall consist of: all the elements that compare less than, all the elements that compare - equal to, and all the elements that compare greater than the key object, in that order.292) - Returns -4 The bsearch function returns a pointer to a matching element of the array, or a null - pointer if no match is found. If two elements compare as equal, which element is - - - 291) That is, if the value passed is p, then the following expressions are always nonzero: - ((char *)p - (char *)base) % size == 0 - (char *)p >= (char *)base - (char *)p < (char *)base + nmemb * size - - 292) In practice, the entire array is sorted according to the comparison function. - -[page 353] - - matched is unspecified. - 7.22.5.2 The qsort function - Synopsis -1 #include - void qsort(void *base, size_t nmemb, size_t size, - int (*compar)(const void *, const void *)); - Description -2 The qsort function sorts an array of nmemb objects, the initial element of which is - pointed to by base. The size of each object is specified by size. -3 The contents of the array are sorted into ascending order according to a comparison - function pointed to by compar, which is called with two arguments that point to the - objects being compared. The function shall return an integer less than, equal to, or - greater than zero if the first argument is considered to be respectively less than, equal to, - or greater than the second. -4 If two elements compare as equal, their order in the resulting sorted array is unspecified. - Returns -5 The qsort function returns no value. - 7.22.6 Integer arithmetic functions - 7.22.6.1 The abs, labs and llabs functions - Synopsis -1 #include - int abs(int j); - long int labs(long int j); - long long int llabs(long long int j); - Description -2 The abs, labs, and llabs functions compute the absolute value of an integer j. If the - result cannot be represented, the behavior is undefined.293) - Returns -3 The abs, labs, and llabs, functions return the absolute value. - - - - - 293) The absolute value of the most negative number cannot be represented in two's complement. - -[page 354] - - 7.22.6.2 The div, ldiv, and lldiv functions - Synopsis -1 #include - div_t div(int numer, int denom); - ldiv_t ldiv(long int numer, long int denom); - lldiv_t lldiv(long long int numer, long long int denom); - Description -2 The div, ldiv, and lldiv, functions compute numer / denom and numer % - denom in a single operation. - Returns -3 The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and - lldiv_t, respectively, comprising both the quotient and the remainder. The structures - shall contain (in either order) the members quot (the quotient) and rem (the remainder), - each of which has the same type as the arguments numer and denom. If either part of - the result cannot be represented, the behavior is undefined. - 7.22.7 Multibyte/wide character conversion functions -1 The behavior of the multibyte character functions is affected by the LC_CTYPE category - of the current locale. For a state-dependent encoding, each function is placed into its - initial conversion state at program startup and can be returned to that state by a call for - which its character pointer argument, s, is a null pointer. Subsequent calls with s as - other than a null pointer cause the internal conversion state of the function to be altered as - necessary. A call with s as a null pointer causes these functions to return a nonzero value - if encodings have state dependency, and zero otherwise.294) Changing the LC_CTYPE - category causes the conversion state of these functions to be indeterminate. - 7.22.7.1 The mblen function - Synopsis -1 #include - int mblen(const char *s, size_t n); - Description -2 If s is not a null pointer, the mblen function determines the number of bytes contained - in the multibyte character pointed to by s. Except that the conversion state of the - mbtowc function is not affected, it is equivalent to - - - - 294) If the locale employs special bytes to change the shift state, these bytes do not produce separate wide - character codes, but are grouped with an adjacent multibyte character. - -[page 355] - - mbtowc((wchar_t *)0, (const char *)0, 0); - mbtowc((wchar_t *)0, s, n); -3 The implementation shall behave as if no library function calls the mblen function. - Returns -4 If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte - character encodings, respectively, do or do not have state-dependent encodings. If s is - not a null pointer, the mblen function either returns 0 (if s points to the null character), - or returns the number of bytes that are contained in the multibyte character (if the next n - or fewer bytes form a valid multibyte character), or returns -1 (if they do not form a valid - multibyte character). - Forward references: the mbtowc function (7.22.7.2). - 7.22.7.2 The mbtowc function - Synopsis -1 #include - int mbtowc(wchar_t * restrict pwc, - const char * restrict s, - size_t n); - Description -2 If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with - the byte pointed to by s to determine the number of bytes needed to complete the next - multibyte character (including any shift sequences). If the function determines that the - next multibyte character is complete and valid, it determines the value of the - corresponding wide character and then, if pwc is not a null pointer, stores that value in - the object pointed to by pwc. If the corresponding wide character is the null wide - character, the function is left in the initial conversion state. -3 The implementation shall behave as if no library function calls the mbtowc function. - Returns -4 If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte - character encodings, respectively, do or do not have state-dependent encodings. If s is - not a null pointer, the mbtowc function either returns 0 (if s points to the null character), - or returns the number of bytes that are contained in the converted multibyte character (if - the next n or fewer bytes form a valid multibyte character), or returns -1 (if they do not - form a valid multibyte character). -5 In no case will the value returned be greater than n or the value of the MB_CUR_MAX - macro. - - -[page 356] - - 7.22.7.3 The wctomb function - Synopsis -1 #include - int wctomb(char *s, wchar_t wc); - Description -2 The wctomb function determines the number of bytes needed to represent the multibyte - character corresponding to the wide character given by wc (including any shift - sequences), and stores the multibyte character representation in the array whose first - element is pointed to by s (if s is not a null pointer). At most MB_CUR_MAX characters - are stored. If wc is a null wide character, a null byte is stored, preceded by any shift - sequence needed to restore the initial shift state, and the function is left in the initial - conversion state. -3 The implementation shall behave as if no library function calls the wctomb function. - Returns -4 If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte - character encodings, respectively, do or do not have state-dependent encodings. If s is - not a null pointer, the wctomb function returns -1 if the value of wc does not correspond - to a valid multibyte character, or returns the number of bytes that are contained in the - multibyte character corresponding to the value of wc. -5 In no case will the value returned be greater than the value of the MB_CUR_MAX macro. - 7.22.8 Multibyte/wide string conversion functions -1 The behavior of the multibyte string functions is affected by the LC_CTYPE category of - the current locale. - 7.22.8.1 The mbstowcs function - Synopsis -1 #include - size_t mbstowcs(wchar_t * restrict pwcs, - const char * restrict s, - size_t n); - Description -2 The mbstowcs function converts a sequence of multibyte characters that begins in the - initial shift state from the array pointed to by s into a sequence of corresponding wide - characters and stores not more than n wide characters into the array pointed to by pwcs. - No multibyte characters that follow a null character (which is converted into a null wide - character) will be examined or converted. Each multibyte character is converted as if by - a call to the mbtowc function, except that the conversion state of the mbtowc function is -[page 357] - - not affected. -3 No more than n elements will be modified in the array pointed to by pwcs. If copying - takes place between objects that overlap, the behavior is undefined. - Returns -4 If an invalid multibyte character is encountered, the mbstowcs function returns - (size_t)(-1). Otherwise, the mbstowcs function returns the number of array - elements modified, not including a terminating null wide character, if any.295) - 7.22.8.2 The wcstombs function - Synopsis -1 #include - size_t wcstombs(char * restrict s, - const wchar_t * restrict pwcs, - size_t n); - Description -2 The wcstombs function converts a sequence of wide characters from the array pointed - to by pwcs into a sequence of corresponding multibyte characters that begins in the - initial shift state, and stores these multibyte characters into the array pointed to by s, - stopping if a multibyte character would exceed the limit of n total bytes or if a null - character is stored. Each wide character is converted as if by a call to the wctomb - function, except that the conversion state of the wctomb function is not affected. -3 No more than n bytes will be modified in the array pointed to by s. If copying takes place - between objects that overlap, the behavior is undefined. - Returns -4 If a wide character is encountered that does not correspond to a valid multibyte character, - the wcstombs function returns (size_t)(-1). Otherwise, the wcstombs function - returns the number of bytes modified, not including a terminating null character, if - any.295) - - - - - 295) The array will not be null-terminated if the value returned is n. - -[page 358] - - 7.23 String handling - 7.23.1 String function conventions -1 The header declares one type and several functions, and defines one - macro useful for manipulating arrays of character type and other objects treated as arrays - of character type.296) The type is size_t and the macro is NULL (both described in - 7.19). Various methods are used for determining the lengths of the arrays, but in all cases - a char * or void * argument points to the initial (lowest addressed) character of the - array. If an array is accessed beyond the end of an object, the behavior is undefined. -2 Where an argument declared as size_t n specifies the length of the array for a - function, n can have the value zero on a call to that function. Unless explicitly stated - otherwise in the description of a particular function in this subclause, pointer arguments - on such a call shall still have valid values, as described in 7.1.4. On such a call, a - function that locates a character finds no occurrence, a function that compares two - character sequences returns zero, and a function that copies characters copies zero - characters. -3 For all functions in this subclause, each character shall be interpreted as if it had the type - unsigned char (and therefore every possible object representation is valid and has a - different value). - 7.23.2 Copying functions - 7.23.2.1 The memcpy function - Synopsis -1 #include - void *memcpy(void * restrict s1, - const void * restrict s2, - size_t n); - Description -2 The memcpy function copies n characters from the object pointed to by s2 into the - object pointed to by s1. If copying takes place between objects that overlap, the behavior - is undefined. - Returns -3 The memcpy function returns the value of s1. - - - - - 296) See ''future library directions'' (7.30.11). - -[page 359] - - 7.23.2.2 The memmove function - Synopsis -1 #include - void *memmove(void *s1, const void *s2, size_t n); - Description -2 The memmove function copies n characters from the object pointed to by s2 into the - object pointed to by s1. Copying takes place as if the n characters from the object - pointed to by s2 are first copied into a temporary array of n characters that does not - overlap the objects pointed to by s1 and s2, and then the n characters from the - temporary array are copied into the object pointed to by s1. - Returns -3 The memmove function returns the value of s1. - 7.23.2.3 The strcpy function - Synopsis -1 #include - char *strcpy(char * restrict s1, - const char * restrict s2); - Description -2 The strcpy function copies the string pointed to by s2 (including the terminating null - character) into the array pointed to by s1. If copying takes place between objects that - overlap, the behavior is undefined. - Returns -3 The strcpy function returns the value of s1. - 7.23.2.4 The strncpy function - Synopsis -1 #include - char *strncpy(char * restrict s1, - const char * restrict s2, - size_t n); - Description -2 The strncpy function copies not more than n characters (characters that follow a null - character are not copied) from the array pointed to by s2 to the array pointed to by - - - - -[page 360] - - s1.297) If copying takes place between objects that overlap, the behavior is undefined. -3 If the array pointed to by s2 is a string that is shorter than n characters, null characters - are appended to the copy in the array pointed to by s1, until n characters in all have been - written. - Returns -4 The strncpy function returns the value of s1. - 7.23.3 Concatenation functions - 7.23.3.1 The strcat function - Synopsis -1 #include - char *strcat(char * restrict s1, - const char * restrict s2); - Description -2 The strcat function appends a copy of the string pointed to by s2 (including the - terminating null character) to the end of the string pointed to by s1. The initial character - of s2 overwrites the null character at the end of s1. If copying takes place between - objects that overlap, the behavior is undefined. - Returns -3 The strcat function returns the value of s1. - 7.23.3.2 The strncat function - Synopsis -1 #include - char *strncat(char * restrict s1, - const char * restrict s2, - size_t n); - Description -2 The strncat function appends not more than n characters (a null character and - characters that follow it are not appended) from the array pointed to by s2 to the end of - the string pointed to by s1. The initial character of s2 overwrites the null character at the - end of s1. A terminating null character is always appended to the result.298) If copying - - 297) Thus, if there is no null character in the first n characters of the array pointed to by s2, the result will - not be null-terminated. - 298) Thus, the maximum number of characters that can end up in the array pointed to by s1 is - strlen(s1)+n+1. - -[page 361] - - takes place between objects that overlap, the behavior is undefined. - Returns -3 The strncat function returns the value of s1. - Forward references: the strlen function (7.23.6.3). - 7.23.4 Comparison functions -1 The sign of a nonzero value returned by the comparison functions memcmp, strcmp, - and strncmp is determined by the sign of the difference between the values of the first - pair of characters (both interpreted as unsigned char) that differ in the objects being - compared. - 7.23.4.1 The memcmp function - Synopsis -1 #include - int memcmp(const void *s1, const void *s2, size_t n); - Description -2 The memcmp function compares the first n characters of the object pointed to by s1 to - the first n characters of the object pointed to by s2.299) - Returns -3 The memcmp function returns an integer greater than, equal to, or less than zero, - accordingly as the object pointed to by s1 is greater than, equal to, or less than the object - pointed to by s2. - 7.23.4.2 The strcmp function - Synopsis -1 #include - int strcmp(const char *s1, const char *s2); - Description -2 The strcmp function compares the string pointed to by s1 to the string pointed to by - s2. - Returns -3 The strcmp function returns an integer greater than, equal to, or less than zero, - accordingly as the string pointed to by s1 is greater than, equal to, or less than the string - - 299) The contents of ''holes'' used as padding for purposes of alignment within structure objects are - indeterminate. Strings shorter than their allocated space and unions may also cause problems in - comparison. - -[page 362] - - pointed to by s2. - 7.23.4.3 The strcoll function - Synopsis -1 #include - int strcoll(const char *s1, const char *s2); - Description -2 The strcoll function compares the string pointed to by s1 to the string pointed to by - s2, both interpreted as appropriate to the LC_COLLATE category of the current locale. - Returns -3 The strcoll function returns an integer greater than, equal to, or less than zero, - accordingly as the string pointed to by s1 is greater than, equal to, or less than the string - pointed to by s2 when both are interpreted as appropriate to the current locale. - 7.23.4.4 The strncmp function - Synopsis -1 #include - int strncmp(const char *s1, const char *s2, size_t n); - Description -2 The strncmp function compares not more than n characters (characters that follow a - null character are not compared) from the array pointed to by s1 to the array pointed to - by s2. - Returns -3 The strncmp function returns an integer greater than, equal to, or less than zero, - accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal - to, or less than the possibly null-terminated array pointed to by s2. - 7.23.4.5 The strxfrm function - Synopsis -1 #include - size_t strxfrm(char * restrict s1, - const char * restrict s2, - size_t n); - Description -2 The strxfrm function transforms the string pointed to by s2 and places the resulting - string into the array pointed to by s1. The transformation is such that if the strcmp - function is applied to two transformed strings, it returns a value greater than, equal to, or - -[page 363] - - less than zero, corresponding to the result of the strcoll function applied to the same - two original strings. No more than n characters are placed into the resulting array - pointed to by s1, including the terminating null character. If n is zero, s1 is permitted to - be a null pointer. If copying takes place between objects that overlap, the behavior is - undefined. - Returns -3 The strxfrm function returns the length of the transformed string (not including the - terminating null character). If the value returned is n or more, the contents of the array - pointed to by s1 are indeterminate. -4 EXAMPLE The value of the following expression is the size of the array needed to hold the - transformation of the string pointed to by s. - 1 + strxfrm(NULL, s, 0) - - 7.23.5 Search functions - 7.23.5.1 The memchr function - Synopsis -1 #include - void *memchr(const void *s, int c, size_t n); - Description -2 The memchr function locates the first occurrence of c (converted to an unsigned - char) in the initial n characters (each interpreted as unsigned char) of the object - pointed to by s. - Returns -3 The memchr function returns a pointer to the located character, or a null pointer if the - character does not occur in the object. - 7.23.5.2 The strchr function - Synopsis -1 #include - char *strchr(const char *s, int c); - Description -2 The strchr function locates the first occurrence of c (converted to a char) in the - string pointed to by s. The terminating null character is considered to be part of the - string. - Returns -3 The strchr function returns a pointer to the located character, or a null pointer if the - character does not occur in the string. -[page 364] - - 7.23.5.3 The strcspn function - Synopsis -1 #include - size_t strcspn(const char *s1, const char *s2); - Description -2 The strcspn function computes the length of the maximum initial segment of the string - pointed to by s1 which consists entirely of characters not from the string pointed to by - s2. - Returns -3 The strcspn function returns the length of the segment. - 7.23.5.4 The strpbrk function - Synopsis -1 #include - char *strpbrk(const char *s1, const char *s2); - Description -2 The strpbrk function locates the first occurrence in the string pointed to by s1 of any - character from the string pointed to by s2. - Returns -3 The strpbrk function returns a pointer to the character, or a null pointer if no character - from s2 occurs in s1. - 7.23.5.5 The strrchr function - Synopsis -1 #include - char *strrchr(const char *s, int c); - Description -2 The strrchr function locates the last occurrence of c (converted to a char) in the - string pointed to by s. The terminating null character is considered to be part of the - string. - Returns -3 The strrchr function returns a pointer to the character, or a null pointer if c does not - occur in the string. - - - - -[page 365] - - 7.23.5.6 The strspn function - Synopsis -1 #include - size_t strspn(const char *s1, const char *s2); - Description -2 The strspn function computes the length of the maximum initial segment of the string - pointed to by s1 which consists entirely of characters from the string pointed to by s2. - Returns -3 The strspn function returns the length of the segment. - 7.23.5.7 The strstr function - Synopsis -1 #include - char *strstr(const char *s1, const char *s2); - Description -2 The strstr function locates the first occurrence in the string pointed to by s1 of the - sequence of characters (excluding the terminating null character) in the string pointed to - by s2. - Returns -3 The strstr function returns a pointer to the located string, or a null pointer if the string - is not found. If s2 points to a string with zero length, the function returns s1. - 7.23.5.8 The strtok function - Synopsis -1 #include - char *strtok(char * restrict s1, - const char * restrict s2); - Description -2 A sequence of calls to the strtok function breaks the string pointed to by s1 into a - sequence of tokens, each of which is delimited by a character from the string pointed to - by s2. The first call in the sequence has a non-null first argument; subsequent calls in the - sequence have a null first argument. The separator string pointed to by s2 may be - different from call to call. -3 The first call in the sequence searches the string pointed to by s1 for the first character - that is not contained in the current separator string pointed to by s2. If no such character - is found, then there are no tokens in the string pointed to by s1 and the strtok function - -[page 366] - - returns a null pointer. If such a character is found, it is the start of the first token. -4 The strtok function then searches from there for a character that is contained in the - current separator string. If no such character is found, the current token extends to the - end of the string pointed to by s1, and subsequent searches for a token will return a null - pointer. If such a character is found, it is overwritten by a null character, which - terminates the current token. The strtok function saves a pointer to the following - character, from which the next search for a token will start. -5 Each subsequent call, with a null pointer as the value of the first argument, starts - searching from the saved pointer and behaves as described above. -6 The strtok function is not required to avoid data races. The implementation shall - behave as if no library function calls the strtok function. - Returns -7 The strtok function returns a pointer to the first character of a token, or a null pointer - if there is no token. -8 EXAMPLE - #include - static char str[] = "?a???b,,,#c"; - char *t; - t = strtok(str, "?"); // t points to the token "a" - t = strtok(NULL, ","); // t points to the token "??b" - t = strtok(NULL, "#,"); // t points to the token "c" - t = strtok(NULL, "?"); // t is a null pointer - - 7.23.6 Miscellaneous functions - 7.23.6.1 The memset function - Synopsis -1 #include - void *memset(void *s, int c, size_t n); - Description -2 The memset function copies the value of c (converted to an unsigned char) into - each of the first n characters of the object pointed to by s. - Returns -3 The memset function returns the value of s. - - - - -[page 367] - - 7.23.6.2 The strerror function - Synopsis -1 #include - char *strerror(int errnum); - Description -2 The strerror function maps the number in errnum to a message string. Typically, - the values for errnum come from errno, but strerror shall map any value of type - int to a message. -3 The strerror function is not required to avoid data races. The implementation shall - behave as if no library function calls the strerror function. - Returns -4 The strerror function returns a pointer to the string, the contents of which are locale- - specific. The array pointed to shall not be modified by the program, but may be - overwritten by a subsequent call to the strerror function. - 7.23.6.3 The strlen function - Synopsis -1 #include - size_t strlen(const char *s); - Description -2 The strlen function computes the length of the string pointed to by s. - Returns -3 The strlen function returns the number of characters that precede the terminating null - character. - - - - -[page 368] - - 7.24 Type-generic math -1 The header includes the headers and and - defines several type-generic macros. -2 Of the and functions without an f (float) or l (long - double) suffix, several have one or more parameters whose corresponding real type is - double. For each such function, except modf, there is a corresponding type-generic - macro.300) The parameters whose corresponding real type is double in the function - synopsis are generic parameters. Use of the macro invokes a function whose - corresponding real type and type domain are determined by the arguments for the generic - parameters.301) -3 Use of the macro invokes a function whose generic parameters have the corresponding - real type determined as follows: - -- First, if any argument for generic parameters has type long double, the type - determined is long double. - -- Otherwise, if any argument for generic parameters has type double or is of integer - type, the type determined is double. - -- Otherwise, the type determined is float. -4 For each unsuffixed function in for which there is a function in - with the same name except for a c prefix, the corresponding type- - generic macro (for both functions) has the same name as the function in . The - corresponding type-generic macro for fabs and cabs is fabs. - - - - - 300) Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to - make available the corresponding ordinary function. - 301) If the type of the argument is not compatible with the type of the parameter for the selected function, - the behavior is undefined. - -[page 369] - - type-generic - function function macro - acos cacos acos - asin casin asin - atan catan atan - acosh cacosh acosh - asinh casinh asinh - atanh catanh atanh - cos ccos cos - sin csin sin - tan ctan tan - cosh ccosh cosh - sinh csinh sinh - tanh ctanh tanh - exp cexp exp - log clog log - pow cpow pow - sqrt csqrt sqrt - fabs cabs fabs - If at least one argument for a generic parameter is complex, then use of the macro invokes - a complex function; otherwise, use of the macro invokes a real function. -5 For each unsuffixed function in without a c-prefixed counterpart in - (except modf), the corresponding type-generic macro has the same - name as the function. These type-generic macros are: - atan2 fma llround remainder - cbrt fmax log10 remquo - ceil fmin log1p rint - copysign fmod log2 round - erf frexp logb scalbn - erfc hypot lrint scalbln - exp2 ilogb lround tgamma - expm1 ldexp nearbyint trunc - fdim lgamma nextafter - floor llrint nexttoward - If all arguments for generic parameters are real, then use of the macro invokes a real - function; otherwise, use of the macro results in undefined behavior. - - - - -[page 370] - -6 For each unsuffixed function in that is not a c-prefixed counterpart to a - function in , the corresponding type-generic macro has the same name as the - function. These type-generic macros are: - carg conj creal - cimag cproj - Use of the macro with any real or complex argument invokes a complex function. -7 EXAMPLE With the declarations - #include - int n; - float f; - double d; - long double ld; - float complex fc; - double complex dc; - long double complex ldc; - functions invoked by use of type-generic macros are shown in the following table: - macro use invokes - exp(n) exp(n), the function - acosh(f) acoshf(f) - sin(d) sin(d), the function - atan(ld) atanl(ld) - log(fc) clogf(fc) - sqrt(dc) csqrt(dc) - pow(ldc, f) cpowl(ldc, f) - remainder(n, n) remainder(n, n), the function - nextafter(d, f) nextafter(d, f), the function - nexttoward(f, ld) nexttowardf(f, ld) - copysign(n, ld) copysignl(n, ld) - ceil(fc) undefined behavior - rint(dc) undefined behavior - fmax(ldc, ld) undefined behavior - carg(n) carg(n), the function - cproj(f) cprojf(f) - creal(d) creal(d), the function - cimag(ld) cimagl(ld) - fabs(fc) cabsf(fc) - carg(dc) carg(dc), the function - cproj(ldc) cprojl(ldc) - - - - -[page 371] - - 7.25 Threads - 7.25.1 Introduction -1 The header defines macros, and declares types, enumeration constants, - and functions that support multiple threads of execution. -2 Implementations that define the macro __STDC_NO_THREADS__ need not provide - this header nor support any of its facilities. -3 The macros are - ONCE_FLAG_INIT - which expands to a value that can be used to initialize an object of type once_flag; - and - TSS_DTOR_ITERATIONS - which expands to an integer constant expression representing the maximum number of - times that destructors will be called when a thread terminates. -4 The types are - cnd_t - which is a complete object type that holds an identifier for a condition variable; - thrd_t - which is a complete object type that holds an identifier for a thread; - tss_t - which is a complete object type that holds an identifier for a thread-specific storage - pointer; - mtx_t - which is a complete object type that holds an identifier for a mutex; - tss_dtor_t - which is the function pointer type void (*)(void*), used for a destructor for a - thread-specific storage pointer; - thrd_start_t - which is the function pointer type int (*)(void*) that is passed to thrd_create - to create a new thread; - once_flag - which is a complete object type that holds a flag for use by call_once; and - - -[page 372] - - xtime - which is a structure type that holds a time specified in seconds and nanoseconds. The - structure shall contain at least the following members, in any order. - time_t sec; - long nsec; -5 The enumeration constants are - mtx_plain - which is passed to mtx_init to create a mutex object that supports neither timeout nor - test and return; - mtx_recursive - which is passed to mtx_init to create a mutex object that supports recursive locking; - mtx_timed - which is passed to mtx_init to create a mutex object that supports timeout; - mtx_try - which is passed to mtx_init to create a mutex object that supports test and return; - thrd_timeout - which is returned by a timed wait function to indicate that the time specified in the call - was reached without acquiring the requested resource; - thrd_success - which is returned by a function to indicate that the requested operation succeeded; - thrd_busy - which is returned by a function to indicate that the requested operation failed because a - resource requested by a test and return function is already in use; - thrd_error - which is returned by a function to indicate that the requested operation failed; and - thrd_nomem - which is returned by a function to indicate that the requested operation failed because it - was unable to allocate memory. - - - - -[page 373] - - 7.25.2 Initialization functions - 7.25.2.1 The call_once function - Synopsis -1 #include - void call_once(once_flag *flag, void (*func)(void)); - Description -2 The call_once function uses the once_flag pointed to by flag to ensure that - func is called exactly once, the first time the call_once function is called with that - value of flag. Completion of an effective call to the call_once function synchronizes - with all subsequent calls to the call_once function with the same value of flag. - Returns -3 The call_once function returns no value. - 7.25.3 Condition variable functions - 7.25.3.1 The cnd_broadcast function - Synopsis -1 #include - int cnd_broadcast(cnd_t *cond); - Description -2 The cnd_broadcast function unblocks all of the threads that are blocked on the - condition variable pointed to by cond at the time of the call. If no threads are blocked - on the condition variable pointed to by cond at the time of the call, the function does - nothing. - Returns -3 The cnd_broadcast function returns thrd_success on success, or thrd_error - if the request could not be honored. - 7.25.3.2 The cnd_destroy function - Synopsis -1 #include - void cnd_destroy(cnd_t *cond); - Description -2 The cnd_destroy function releases all resources used by the condition variable - pointed to by cond. The cnd_destroy function requires that no threads be blocked - waiting for the condition variable pointed to by cond. - -[page 374] - - Returns -3 The cnd_destroy function returns no value. - 7.25.3.3 The cnd_init function - Synopsis -1 #include - int cnd_init(cnd_t *cond); - Description -2 The cnd_init function creates a condition variable. If it succeeds it sets the variable - pointed to by cond to a value that uniquely identifies the newly created condition - variable. A thread that calls cnd_wait on a newly created condition variable will - block. - Returns -3 The cnd_init function returns thrd_success on success, or thrd_nomem if no - memory could be allocated for the newly created condition, or thrd_error if the - request could not be honored. - 7.25.3.4 The cnd_signal function - Synopsis -1 #include - int cnd_signal(cnd_t *cond); - Description -2 The cnd_signal function unblocks one of the threads that are blocked on the - condition variable pointed to by cond at the time of the call. If no threads are blocked - on the condition variable at the time of the call, the function does nothing and return - success. - Returns -3 The cnd_signal function returns thrd_success on success or thrd_error if - the request could not be honored. - 7.25.3.5 The cnd_timedwait function - Synopsis -1 #include - int cnd_timedwait(cnd_t *cond, mtx_t *mtx, - const xtime *xt); - - - - -[page 375] - - Description -2 The cnd_timedwait function atomically unlocks the mutex pointed to by mtx and - endeavors to block until the condition variable pointed to by cond is signaled by a call to - cnd_signal or to cnd_broadcast, or until after the time specified by the xtime - object pointed to by xt. When the calling thread becomes unblocked it locks the variable - pointed to by mtx before it returns. The cnd_timedwait function requires that the - mutex pointed to by mtx be locked by the calling thread. - Returns -3 The cnd_timedwait function returns thrd_success upon success, or - thrd_timeout if the time specified in the call was reached without acquiring the - requested resource, or thrd_error if the request could not be honored. - 7.25.3.6 The cnd_wait function - Synopsis -1 #include - int cnd_wait(cnd_t *cond, mtx_t *mtx); - Description -2 The cnd_wait function atomically unlocks the mutex pointed to by mtx and endeavors - to block until the condition variable pointed to by cond is signaled by a call to - cnd_signal or to cnd_broadcast. When the calling thread becomes unblocked it - locks the mutex pointed to by mtx before it returns. If the mutex pointed to by mtx is - not locked by the calling thread, the cnd_wait function will act as if the abort - function is called. - Returns -3 The cnd_wait function returns thrd_success on success or thrd_error if the - request could not be honored. - 7.25.4 Mutex functions - 7.25.4.1 The mtx_destroy function - Synopsis -1 #include - void mtx_destroy(mtx_t *mtx); - Description -2 The mtx_destroy function releases any resources used by the mutex pointed to by - mtx. No threads can be blocked waiting for the mutex pointed to by mtx. - - - -[page 376] - - Returns -3 The mtx_destroy function returns no value. - 7.25.4.2 The mtx_init function - Synopsis -1 #include - int mtx_init(mtx_t *mtx, int type); - Description -2 The mtx_init function creates a mutex object with properties indicated by type, - which must have one of the six values: - mtx_plain for a simple non-recursive mutex, - mtx_timed for a non-recursive mutex that supports timeout, - mtx_try for a non-recursive mutex that supports test and return, - mtx_plain | mtx_recursive for a simple recursive mutex, - mtx_timed | mtx_recursive for a recursive mutex that supports timeout, or - mtx_try | mtx_recursive for a recursive mutex that supports test and return. -3 If the mtx_init function succeeds, it sets the mutex pointed to by mtx to a value that - uniquely identifies the newly created mutex. - Returns -4 The mtx_init function returns thrd_success on success, or thrd_error if the - request could not be honored. - 7.25.4.3 The mtx_lock function - Synopsis -1 #include - int mtx_lock(mtx_t *mtx); - Description -2 The mtx_lock function blocks until it locks the mutex pointed to by mtx. If the mutex - is non-recursive, it shall not be locked by the calling thread. Prior calls to mtx_unlock - on the same mutex shall synchronize with this operation. - Returns -3 The mtx_lock function returns thrd_success on success, or thrd_busy if the - resource requested is already in use, or thrd_error if the request could not be - honored. - - - - -[page 377] - - 7.25.4.4 The mtx_timedlock function - Synopsis -1 #include - int mtx_timedlock(mtx_t *mtx, const xtime *xt); - Description -2 The mtx_timedlock function endeavors to block until it locks the mutex pointed to by - mtx or until the time specified by the xtime object xt has passed. The specified mutex - shall support timeout. Prior calls to mtx_unlock on the same mutex shall synchronize - with this operation. * - Returns -3 The mtx_timedlock function returns thrd_success on success, or thrd_busy - if the resource requested is already in use, or thrd_timeout if the time specified was - reached without acquiring the requested resource, or thrd_error if the request could - not be honored. - 7.25.4.5 The mtx_trylock function - Synopsis -1 #include - int mtx_trylock(mtx_t *mtx); - Description -2 The mtx_trylock function endeavors to lock the mutex pointed to by mtx. The - specified mutex shall support either test and return or timeout. If the mutex is already - locked, the function returns without blocking. Prior calls to mtx_unlock on the same - mutex shall synchronize with this operation. * - Returns -3 The mtx_trylock function returns thrd_success on success, or thrd_busy if - the resource requested is already in use, or thrd_error if the request could not be - honored. - 7.25.4.6 The mtx_unlock function - Synopsis -1 #include - int mtx_unlock(mtx_t *mtx); - Description -2 The mtx_unlock function unlocks the mutex pointed to by mtx. The mutex pointed to - by mtx shall be locked by the calling thread. - -[page 378] - - Returns -3 The mtx_unlock function returns thrd_success on success or thrd_error if - the request could not be honored. - 7.25.5 Thread functions - 7.25.5.1 The thrd_create function - Synopsis -1 #include - int thrd_create(thrd_t *thr, thrd_start_t func, - void *arg); - Description -2 The thrd_create function creates a new thread executing func(arg). If the - thrd_create function succeeds, it sets the thread thr to a value that uniquely - identifies the newly created thread. - Returns -3 The thrd_create function returns thrd_success on success, or thrd_nomem if - no memory could be allocated for the thread requested, or thrd_error if the request - could not be honored. - 7.25.5.2 The thrd_current function - Synopsis -1 #include - thrd_t thrd_current(void); - Description -2 The thrd_current function identifies the thread that called it. - Returns -3 The thrd_current function returns a value that uniquely identifies the thread that - called it. - 7.25.5.3 The thrd_detach function - Synopsis -1 #include - int thrd_detach(thrd_t thr); - Description -2 The thrd_detach function tells the operating system to dispose of any resources - allocated to the thread identified by thr when that thread terminates. The value of the - -[page 379] - - thread identified by thr value shall not have been set by a call to thrd_join or - thrd_detach. - Returns -3 The thrd_detach function returns thrd_success on success or thrd_error if - the request could not be honored. - 7.25.5.4 The thrd_equal function - Synopsis -1 #include - int thrd_equal(thrd_t thr0, thrd_t thr1); - Description -2 The thrd_equal function will determine whether the thread identified by thr0 refers - to the thread identified by thr1. - Returns -3 The thrd_equal function returns zero if the thread thr0 and the thread thr1 refer to - different threads. Otherwise the thrd_equal function returns a nonzero value. - 7.25.5.5 The thrd_exit function - Synopsis -1 #include - void thrd_exit(int res); - Description -2 The thrd_exit function terminates execution of the calling thread and sets its result - code to res. - Returns -3 The thrd_exit function returns no value. - 7.25.5.6 The thrd_join function - Synopsis -1 #include - int thrd_join(thrd_t thr, int *res); - Description -2 The thrd_join function blocks until the thread identified by thr has terminated. If - the parameter res is not a null pointer, it stores the thread's result code in the integer - pointed to by res. The value of the thread identified by thr shall not have been set by a - call to thrd_join or thrd_detach. - -[page 380] - - Returns -3 The thrd_join function returns thrd_success on success or thrd_error if the - request could not be honored. - 7.25.5.7 The thrd_sleep function - Synopsis -1 #include - void thrd_sleep(const xtime *xt); - Description -2 The thrd_sleep function suspends execution of the calling thread until after the time - specified by the xtime object pointed to by xt. - Returns -3 The thrd_sleep function returns no value. - 7.25.5.8 The thrd_yield function - Synopsis -1 #include - void thrd_yield(void); - Description -2 The thrd_yield function endeavors to permit other threads to run, even if the current - thread would ordinarily continue to run. - Returns -3 The thrd_yield function returns no value. - 7.25.6 Thread-specific storage functions - 7.25.6.1 The tss_create function - Synopsis -1 #include - int tss_create(tss_t *key, tss_dtor_t dtor); - Description -2 The tss_create function creates a thread-specific storage pointer with destructor - dtor, which may be null. - Returns -3 If the tss_create function is successful, it sets the thread-specific storage pointed to - by key to a value that uniquely identifies the newly created pointer and returns - thrd_success; otherwise, thrd_error is returned and the thread-specific storage -[page 381] - - pointed to by key is set to an undefined value. - 7.25.6.2 The tss_delete function - Synopsis -1 #include - void tss_delete(tss_t key); - Description -2 The tss_delete function releases any resources used by the thread-specific storage - identified by key. - Returns -3 The tss_delete function returns no value. - 7.25.6.3 The tss_get function - Synopsis -1 #include - void *tss_get(tss_t key); - Description -2 The tss_get function returns the value for the current thread held in the thread-specific - storage identified by key. - Returns -3 The tss_get function returns the value for the current thread if successful, or zero if - unsuccessful. - 7.25.6.4 The tss_set function - Synopsis -1 #include - int tss_set(tss_t key, void *val); - Description -2 The tss_set function sets the value for the current thread held in the thread-specific - storage identified by key to val. - Returns -3 The tss_set function returns thrd_success on success or thrd_error if the - request could not be honored. - - - - -[page 382] - - 7.25.7 Time functions - 7.25.7.1 The xtime_get function - Synopsis -1 #include - int xtime_get(xtime *xt, int base); - Description -2 The xtime_get function sets the xtime object pointed to by xt to hold the current - time based on the time base base. - Returns -3 If the xtime_get function is successful it returns the nonzero value base, which must - be TIME_UTC; otherwise, it returns zero.302) - - - - - 302) Although an xtime object describes times with nanosecond resolution, the actual resolution in an - xtime object is system dependent. - -[page 383] - - 7.26 Date and time - 7.26.1 Components of time -1 The header defines two macros, and declares several types and functions for - manipulating time. Many functions deal with a calendar time that represents the current - date (according to the Gregorian calendar) and time. Some functions deal with local - time, which is the calendar time expressed for some specific time zone, and with Daylight - Saving Time, which is a temporary change in the algorithm for determining local time. - The local time zone and Daylight Saving Time are implementation-defined. -2 The macros defined are NULL (described in 7.19); and - CLOCKS_PER_SEC - which expands to an expression with type clock_t (described below) that is the - number per second of the value returned by the clock function. -3 The types declared are size_t (described in 7.19); - clock_t - and - time_t - which are arithmetic types capable of representing times; and - struct tm - which holds the components of a calendar time, called the broken-down time. -4 The range and precision of times representable in clock_t and time_t are - implementation-defined. The tm structure shall contain at least the following members, - in any order. The semantics of the members and their normal ranges are expressed in the - comments.303) - int tm_sec; // seconds after the minute -- [0, 60] - int tm_min; // minutes after the hour -- [0, 59] - int tm_hour; // hours since midnight -- [0, 23] - int tm_mday; // day of the month -- [1, 31] - int tm_mon; // months since January -- [0, 11] - int tm_year; // years since 1900 - int tm_wday; // days since Sunday -- [0, 6] - int tm_yday; // days since January 1 -- [0, 365] - int tm_isdst; // Daylight Saving Time flag - - - - 303) The range [0, 60] for tm_sec allows for a positive leap second. - -[page 384] - - The value of tm_isdst is positive if Daylight Saving Time is in effect, zero if Daylight - Saving Time is not in effect, and negative if the information is not available. - 7.26.2 Time manipulation functions - 7.26.2.1 The clock function - Synopsis -1 #include - clock_t clock(void); - Description -2 The clock function determines the processor time used. - Returns -3 The clock function returns the implementation's best approximation to the processor - time used by the program since the beginning of an implementation-defined era related - only to the program invocation. To determine the time in seconds, the value returned by - the clock function should be divided by the value of the macro CLOCKS_PER_SEC. If - the processor time used is not available or its value cannot be represented, the function - returns the value (clock_t)(-1).304) - 7.26.2.2 The difftime function - Synopsis -1 #include - double difftime(time_t time1, time_t time0); - Description -2 The difftime function computes the difference between two calendar times: time1 - - time0. - Returns -3 The difftime function returns the difference expressed in seconds as a double. - - - - - 304) In order to measure the time spent in a program, the clock function should be called at the start of - the program and its return value subtracted from the value returned by subsequent calls. - -[page 385] - - 7.26.2.3 The mktime function - Synopsis -1 #include - time_t mktime(struct tm *timeptr); - Description -2 The mktime function converts the broken-down time, expressed as local time, in the - structure pointed to by timeptr into a calendar time value with the same encoding as - that of the values returned by the time function. The original values of the tm_wday - and tm_yday components of the structure are ignored, and the original values of the - other components are not restricted to the ranges indicated above.305) On successful - completion, the values of the tm_wday and tm_yday components of the structure are - set appropriately, and the other components are set to represent the specified calendar - time, but with their values forced to the ranges indicated above; the final value of - tm_mday is not set until tm_mon and tm_year are determined. - Returns -3 The mktime function returns the specified calendar time encoded as a value of type - time_t. If the calendar time cannot be represented, the function returns the value - (time_t)(-1). -4 EXAMPLE What day of the week is July 4, 2001? - #include - #include - static const char *const wday[] = { - "Sunday", "Monday", "Tuesday", "Wednesday", - "Thursday", "Friday", "Saturday", "-unknown-" - }; - struct tm time_str; - /* ... */ - - - - - 305) Thus, a positive or zero value for tm_isdst causes the mktime function to presume initially that - Daylight Saving Time, respectively, is or is not in effect for the specified time. A negative value - causes it to attempt to determine whether Daylight Saving Time is in effect for the specified time. - -[page 386] - - time_str.tm_year = 2001 - 1900; - time_str.tm_mon = 7 - 1; - time_str.tm_mday = 4; - time_str.tm_hour = 0; - time_str.tm_min = 0; - time_str.tm_sec = 1; - time_str.tm_isdst = -1; - if (mktime(&time_str) == (time_t)(-1)) - time_str.tm_wday = 7; - printf("%s\n", wday[time_str.tm_wday]); - - 7.26.2.4 The time function - Synopsis -1 #include - time_t time(time_t *timer); - Description -2 The time function determines the current calendar time. The encoding of the value is - unspecified. - Returns -3 The time function returns the implementation's best approximation to the current - calendar time. The value (time_t)(-1) is returned if the calendar time is not - available. If timer is not a null pointer, the return value is also assigned to the object it - points to. - 7.26.3 Time conversion functions -1 Except for the strftime function, these functions each return a pointer to one of two - types of static objects: a broken-down time structure or an array of char. Execution of - any of the functions that return a pointer to one of these object types may overwrite the - information in any object of the same type pointed to by the value returned from any - previous call to any of them and the functions are not required to avoid data races. The - implementation shall behave as if no other library functions call these functions. - 7.26.3.1 The asctime function - Synopsis -1 #include - char *asctime(const struct tm *timeptr); - Description -2 The asctime function converts the broken-down time in the structure pointed to by - timeptr into a string in the form - Sun Sep 16 01:03:52 1973\n\0 - -[page 387] - - using the equivalent of the following algorithm. - char *asctime(const struct tm *timeptr) - { - static const char wday_name[7][3] = { - "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" - }; - static const char mon_name[12][3] = { - "Jan", "Feb", "Mar", "Apr", "May", "Jun", - "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" - }; - static char result[26]; - sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n", - wday_name[timeptr->tm_wday], - mon_name[timeptr->tm_mon], - timeptr->tm_mday, timeptr->tm_hour, - timeptr->tm_min, timeptr->tm_sec, - 1900 + timeptr->tm_year); - return result; - } -3 If any of the fields of the broken-down time contain values that are outside their normal - ranges,306) the behavior of the asctime function is undefined. Likewise, if the - calculated year exceeds four digits or is less than the year 1000, the behavior is - undefined. - Returns -4 The asctime function returns a pointer to the string. - 7.26.3.2 The ctime function - Synopsis -1 #include - char *ctime(const time_t *timer); - Description -2 The ctime function converts the calendar time pointed to by timer to local time in the - form of a string. It is equivalent to - asctime(localtime(timer)) - - - - 306) See 7.26.1. - -[page 388] - - Returns -3 The ctime function returns the pointer returned by the asctime function with that - broken-down time as argument. - Forward references: the localtime function (7.26.3.4). - 7.26.3.3 The gmtime function - Synopsis -1 #include - struct tm *gmtime(const time_t *timer); - Description -2 The gmtime function converts the calendar time pointed to by timer into a broken- - down time, expressed as UTC. - Returns -3 The gmtime function returns a pointer to the broken-down time, or a null pointer if the - specified time cannot be converted to UTC. - 7.26.3.4 The localtime function - Synopsis -1 #include - struct tm *localtime(const time_t *timer); - Description -2 The localtime function converts the calendar time pointed to by timer into a - broken-down time, expressed as local time. - Returns -3 The localtime function returns a pointer to the broken-down time, or a null pointer if - the specified time cannot be converted to local time. - 7.26.3.5 The strftime function - Synopsis -1 #include - size_t strftime(char * restrict s, - size_t maxsize, - const char * restrict format, - const struct tm * restrict timeptr); - - - - -[page 389] - - Description -2 The strftime function places characters into the array pointed to by s as controlled by - the string pointed to by format. The format shall be a multibyte character sequence, - beginning and ending in its initial shift state. The format string consists of zero or - more conversion specifiers and ordinary multibyte characters. A conversion specifier - consists of a % character, possibly followed by an E or O modifier character (described - below), followed by a character that determines the behavior of the conversion specifier. - All ordinary multibyte characters (including the terminating null character) are copied - unchanged into the array. If copying takes place between objects that overlap, the - behavior is undefined. No more than maxsize characters are placed into the array. -3 Each conversion specifier is replaced by appropriate characters as described in the - following list. The appropriate characters are determined using the LC_TIME category - of the current locale and by the values of zero or more members of the broken-down time - structure pointed to by timeptr, as specified in brackets in the description. If any of - the specified values is outside the normal range, the characters stored are unspecified. - %a is replaced by the locale's abbreviated weekday name. [tm_wday] - %A is replaced by the locale's full weekday name. [tm_wday] - %b is replaced by the locale's abbreviated month name. [tm_mon] - %B is replaced by the locale's full month name. [tm_mon] - %c is replaced by the locale's appropriate date and time representation. [all specified - in 7.26.1] - %C is replaced by the year divided by 100 and truncated to an integer, as a decimal - number (00-99). [tm_year] - %d is replaced by the day of the month as a decimal number (01-31). [tm_mday] - %D is equivalent to ''%m/%d/%y''. [tm_mon, tm_mday, tm_year] - %e is replaced by the day of the month as a decimal number (1-31); a single digit is - preceded by a space. [tm_mday] - %F is equivalent to ''%Y-%m-%d'' (the ISO 8601 date format). [tm_year, tm_mon, - tm_mday] - %g is replaced by the last 2 digits of the week-based year (see below) as a decimal - number (00-99). [tm_year, tm_wday, tm_yday] - %G is replaced by the week-based year (see below) as a decimal number (e.g., 1997). - [tm_year, tm_wday, tm_yday] - %h is equivalent to ''%b''. [tm_mon] - %H is replaced by the hour (24-hour clock) as a decimal number (00-23). [tm_hour] - %I is replaced by the hour (12-hour clock) as a decimal number (01-12). [tm_hour] - %j is replaced by the day of the year as a decimal number (001-366). [tm_yday] - %m is replaced by the month as a decimal number (01-12). [tm_mon] - %M is replaced by the minute as a decimal number (00-59). [tm_min] - %n is replaced by a new-line character. - -[page 390] - - %p is replaced by the locale's equivalent of the AM/PM designations associated with a - 12-hour clock. [tm_hour] - %r is replaced by the locale's 12-hour clock time. [tm_hour, tm_min, tm_sec] - %R is equivalent to ''%H:%M''. [tm_hour, tm_min] - %S is replaced by the second as a decimal number (00-60). [tm_sec] - %t is replaced by a horizontal-tab character. - %T is equivalent to ''%H:%M:%S'' (the ISO 8601 time format). [tm_hour, tm_min, - tm_sec] - %u is replaced by the ISO 8601 weekday as a decimal number (1-7), where Monday - is 1. [tm_wday] - %U is replaced by the week number of the year (the first Sunday as the first day of week - 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday] - %V is replaced by the ISO 8601 week number (see below) as a decimal number - (01-53). [tm_year, tm_wday, tm_yday] - %w is replaced by the weekday as a decimal number (0-6), where Sunday is 0. - [tm_wday] - %W is replaced by the week number of the year (the first Monday as the first day of - week 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday] - %x is replaced by the locale's appropriate date representation. [all specified in 7.26.1] - %X is replaced by the locale's appropriate time representation. [all specified in 7.26.1] - %y is replaced by the last 2 digits of the year as a decimal number (00-99). - [tm_year] - %Y is replaced by the year as a decimal number (e.g., 1997). [tm_year] - %z is replaced by the offset from UTC in the ISO 8601 format ''-0430'' (meaning 4 - hours 30 minutes behind UTC, west of Greenwich), or by no characters if no time - zone is determinable. [tm_isdst] - %Z is replaced by the locale's time zone name or abbreviation, or by no characters if no - time zone is determinable. [tm_isdst] - %% is replaced by %. -4 Some conversion specifiers can be modified by the inclusion of an E or O modifier - character to indicate an alternative format or specification. If the alternative format or - specification does not exist for the current locale, the modifier is ignored. - %Ec is replaced by the locale's alternative date and time representation. - %EC is replaced by the name of the base year (period) in the locale's alternative - representation. - %Ex is replaced by the locale's alternative date representation. - %EX is replaced by the locale's alternative time representation. - %Ey is replaced by the offset from %EC (year only) in the locale's alternative - representation. - %EY is replaced by the locale's full alternative year representation. - -[page 391] - - %Od is replaced by the day of the month, using the locale's alternative numeric symbols - (filled as needed with leading zeros, or with leading spaces if there is no alternative - symbol for zero). - %Oe is replaced by the day of the month, using the locale's alternative numeric symbols - (filled as needed with leading spaces). - %OH is replaced by the hour (24-hour clock), using the locale's alternative numeric - symbols. - %OI is replaced by the hour (12-hour clock), using the locale's alternative numeric - symbols. - %Om is replaced by the month, using the locale's alternative numeric symbols. - %OM is replaced by the minutes, using the locale's alternative numeric symbols. - %OS is replaced by the seconds, using the locale's alternative numeric symbols. - %Ou is replaced by the ISO 8601 weekday as a number in the locale's alternative - representation, where Monday is 1. - %OU is replaced by the week number, using the locale's alternative numeric symbols. - %OV is replaced by the ISO 8601 week number, using the locale's alternative numeric - symbols. - %Ow is replaced by the weekday as a number, using the locale's alternative numeric - symbols. - %OW is replaced by the week number of the year, using the locale's alternative numeric - symbols. - %Oy is replaced by the last 2 digits of the year, using the locale's alternative numeric - symbols. -5 %g, %G, and %V give values according to the ISO 8601 week-based year. In this system, - weeks begin on a Monday and week 1 of the year is the week that includes January 4th, - which is also the week that includes the first Thursday of the year, and is also the first - week that contains at least four days in the year. If the first Monday of January is the - 2nd, 3rd, or 4th, the preceding days are part of the last week of the preceding year; thus, - for Saturday 2nd January 1999, %G is replaced by 1998 and %V is replaced by 53. If - December 29th, 30th, or 31st is a Monday, it and any following days are part of week 1 of - the following year. Thus, for Tuesday 30th December 1997, %G is replaced by 1998 and - %V is replaced by 01. -6 If a conversion specifier is not one of the above, the behavior is undefined. -7 In the "C" locale, the E and O modifiers are ignored and the replacement strings for the - following specifiers are: - %a the first three characters of %A. - %A one of ''Sunday'', ''Monday'', ... , ''Saturday''. - %b the first three characters of %B. - %B one of ''January'', ''February'', ... , ''December''. - %c equivalent to ''%a %b %e %T %Y''. -[page 392] - - %p one of ''AM'' or ''PM''. - %r equivalent to ''%I:%M:%S %p''. - %x equivalent to ''%m/%d/%y''. - %X equivalent to %T. - %Z implementation-defined. - Returns -8 If the total number of resulting characters including the terminating null character is not - more than maxsize, the strftime function returns the number of characters placed - into the array pointed to by s not including the terminating null character. Otherwise, - zero is returned and the contents of the array are indeterminate. - - - - -[page 393] - - 7.27 Unicode utilities -1 The header declares types and functions for manipulating Unicode - characters. -2 The types declared are mbstate_t (described in 7.29.1) and size_t (described in - 7.19); - char16_t - which is an unsigned integer type used for 16-bit characters and is the same type as - uint_least16_t (described in 7.20.1.2); and - char32_t - which is an unsigned integer type used for 32-bit characters and is the same type as - uint_least32_t (also described in 7.20.1.2). - 7.27.1 Restartable multibyte/wide character conversion functions -1 These functions have a parameter, ps, of type pointer to mbstate_t that points to an - object that can completely describe the current conversion state of the associated - multibyte character sequence, which the functions alter as necessary. If ps is a null - pointer, each function uses its own internal mbstate_t object instead, which is - initialized at program startup to the initial conversion state; the functions are not required - to avoid data races in this case. The implementation behaves as if no library function - calls these functions with a null pointer for ps. - 7.27.1.1 The mbrtoc16 function - Synopsis -1 #include - size_t mbrtoc16(char16_t * restrict pc16, - const char * restrict s, size_t n, - mbstate_t * restrict ps); - Description -2 If s is a null pointer, the mbrtoc16 function is equivalent to the call: - mbrtoc16(NULL, "", 1, ps) - In this case, the values of the parameters pc16 and n are ignored. -3 If s is not a null pointer, the mbrtoc16 function inspects at most n bytes beginning with - the byte pointed to by s to determine the number of bytes needed to complete the next - multibyte character (including any shift sequences). If the function determines that the - next multibyte character is complete and valid, it determines the values of the - corresponding wide characters and then, if pc16 is not a null pointer, stores the value of - the first (or only) such character in the object pointed to by pc16. Subsequent calls will -[page 394] - - store successive wide characters without consuming any additional input until all the - characters have been stored. If the corresponding wide character is the null wide - character, the resulting state described is the initial conversion state. - Returns -4 The mbrtoc16 function returns the first of the following that applies (given the current - conversion state): - 0 if the next n or fewer bytes complete the multibyte character that - corresponds to the null wide character (which is the value stored). - between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte - character (which is the value stored); the value returned is the number - of bytes that complete the multibyte character. - (size_t)(-3) if the next character resulting from a previous call has been stored (no - bytes from the input have been consumed by this call). - (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid) - multibyte character, and all n bytes have been processed (no value is - stored).307) - (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes - do not contribute to a complete and valid multibyte character (no - value is stored); the value of the macro EILSEQ is stored in errno, - and the conversion state is unspecified. - 7.27.1.2 The c16rtomb function - Synopsis -1 #include - size_t c16rtomb(char * restrict s, char16_t c16, - mbstate_t * restrict ps); - Description -2 If s is a null pointer, the c16rtomb function is equivalent to the call - c16rtomb(buf, L'\0', ps) - where buf is an internal buffer. -3 If s is not a null pointer, the c16rtomb function determines the number of bytes needed - to represent the multibyte character that corresponds to the wide character given by c16 - (including any shift sequences), and stores the multibyte character representation in the - - 307) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a - sequence of redundant shift sequences (for implementations with state-dependent encodings). - -[page 395] - - array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If - c16 is a null wide character, a null byte is stored, preceded by any shift sequence needed - to restore the initial shift state; the resulting state described is the initial conversion state. - Returns -4 The c16rtomb function returns the number of bytes stored in the array object (including - any shift sequences). When c16 is not a valid wide character, an encoding error occurs: - the function stores the value of the macro EILSEQ in errno and returns - (size_t)(-1); the conversion state is unspecified. - 7.27.1.3 The mbrtoc32 function - Synopsis -1 #include - size_t mbrtoc32(char32_t * restrict pc32, - const char * restrict s, size_t n, - mbstate_t * restrict ps); - Description -2 If s is a null pointer, the mbrtoc32 function is equivalent to the call: - mbrtoc32(NULL, "", 1, ps) - In this case, the values of the parameters pc32 and n are ignored. -3 If s is not a null pointer, the mbrtoc32 function inspects at most n bytes beginning with - the byte pointed to by s to determine the number of bytes needed to complete the next - multibyte character (including any shift sequences). If the function determines that the - next multibyte character is complete and valid, it determines the values of the - corresponding wide characters and then, if pc32 is not a null pointer, stores the value of - the first (or only) such character in the object pointed to by pc32. Subsequent calls will - store successive wide characters without consuming any additional input until all the - characters have been stored. If the corresponding wide character is the null wide - character, the resulting state described is the initial conversion state. - Returns -4 The mbrtoc32 function returns the first of the following that applies (given the current - conversion state): - 0 if the next n or fewer bytes complete the multibyte character that - corresponds to the null wide character (which is the value stored). - between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte - character (which is the value stored); the value returned is the number - of bytes that complete the multibyte character. - - -[page 396] - - (size_t)(-3) if the next character resulting from a previous call has been stored (no - bytes from the input have been consumed by this call). - (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid) - multibyte character, and all n bytes have been processed (no value is - stored).308) - (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes - do not contribute to a complete and valid multibyte character (no - value is stored); the value of the macro EILSEQ is stored in errno, - and the conversion state is unspecified. - 7.27.1.4 The c32rtomb function - Synopsis -1 #include - size_t c32rtomb(char * restrict s, char32_t c32, - mbstate_t * restrict ps); - Description -2 If s is a null pointer, the c32rtomb function is equivalent to the call - c32rtomb(buf, L'\0', ps) - where buf is an internal buffer. -3 If s is not a null pointer, the c32rtomb function determines the number of bytes needed - to represent the multibyte character that corresponds to the wide character given by c32 - (including any shift sequences), and stores the multibyte character representation in the - array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If - c32 is a null wide character, a null byte is stored, preceded by any shift sequence needed - to restore the initial shift state; the resulting state described is the initial conversion state. - Returns -4 The c32rtomb function returns the number of bytes stored in the array object (including - any shift sequences). When c32 is not a valid wide character, an encoding error occurs: - the function stores the value of the macro EILSEQ in errno and returns - (size_t)(-1); the conversion state is unspecified. - - - - - 308) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a - sequence of redundant shift sequences (for implementations with state-dependent encodings). - -[page 397] - - 7.28 Extended multibyte and wide character utilities - 7.28.1 Introduction -1 The header defines four macros, and declares four data types, one tag, and - many functions.309) -2 The types declared are wchar_t and size_t (both described in 7.19); - mbstate_t - which is a complete object type other than an array type that can hold the conversion state - information necessary to convert between sequences of multibyte characters and wide - characters; - wint_t - which is an integer type unchanged by default argument promotions that can hold any - value corresponding to members of the extended character set, as well as at least one - value that does not correspond to any member of the extended character set (see WEOF - below);310) and - struct tm - which is declared as an incomplete structure type (the contents are described in 7.26.1). -3 The macros defined are NULL (described in 7.19); WCHAR_MIN and WCHAR_MAX - (described in 7.20.3); and - WEOF - which expands to a constant expression of type wint_t whose value does not - correspond to any member of the extended character set.311) It is accepted (and returned) - by several functions in this subclause to indicate end-of-file, that is, no more input from a - stream. It is also used as a wide character value that does not correspond to any member - of the extended character set. -4 The functions declared are grouped as follows: - -- Functions that perform input and output of wide characters, or multibyte characters, - or both; - -- Functions that provide wide string numeric conversion; - -- Functions that perform general wide string manipulation; - - - 309) See ''future library directions'' (7.30.12). - 310) wchar_t and wint_t can be the same integer type. - 311) The value of the macro WEOF may differ from that of EOF and need not be negative. - -[page 398] - - -- Functions for wide string date and time conversion; and - -- Functions that provide extended capabilities for conversion between multibyte and - wide character sequences. -5 Unless explicitly stated otherwise, if the execution of a function described in this - subclause causes copying to take place between objects that overlap, the behavior is - undefined. - 7.28.2 Formatted wide character input/output functions -1 The formatted wide character input/output functions shall behave as if there is a sequence - point after the actions associated with each specifier.312) - 7.28.2.1 The fwprintf function - Synopsis -1 #include - #include - int fwprintf(FILE * restrict stream, - const wchar_t * restrict format, ...); - Description -2 The fwprintf function writes output to the stream pointed to by stream, under - control of the wide string pointed to by format that specifies how subsequent arguments - are converted for output. If there are insufficient arguments for the format, the behavior - is undefined. If the format is exhausted while arguments remain, the excess arguments - are evaluated (as always) but are otherwise ignored. The fwprintf function returns - when the end of the format string is encountered. -3 The format is composed of zero or more directives: ordinary wide characters (not %), - which are copied unchanged to the output stream; and conversion specifications, each of - which results in fetching zero or more subsequent arguments, converting them, if - applicable, according to the corresponding conversion specifier, and then writing the - result to the output stream. -4 Each conversion specification is introduced by the wide character %. After the %, the - following appear in sequence: - -- Zero or more flags (in any order) that modify the meaning of the conversion - specification. - -- An optional minimum field width. If the converted value has fewer wide characters - than the field width, it is padded with spaces (by default) on the left (or right, if the - - - 312) The fwprintf functions perform writes to memory for the %n specifier. - -[page 399] - - left adjustment flag, described later, has been given) to the field width. The field - width takes the form of an asterisk * (described later) or a nonnegative decimal - integer.313) - -- An optional precision that gives the minimum number of digits to appear for the d, i, - o, u, x, and X conversions, the number of digits to appear after the decimal-point - wide character for a, A, e, E, f, and F conversions, the maximum number of - significant digits for the g and G conversions, or the maximum number of wide - characters to be written for s conversions. The precision takes the form of a period - (.) followed either by an asterisk * (described later) or by an optional decimal - integer; if only the period is specified, the precision is taken as zero. If a precision - appears with any other conversion specifier, the behavior is undefined. - -- An optional length modifier that specifies the size of the argument. - -- A conversion specifier wide character that specifies the type of conversion to be - applied. -5 As noted above, a field width, or precision, or both, may be indicated by an asterisk. In - this case, an int argument supplies the field width or precision. The arguments - specifying field width, or precision, or both, shall appear (in that order) before the - argument (if any) to be converted. A negative field width argument is taken as a - flag - followed by a positive field width. A negative precision argument is taken as if the - precision were omitted. -6 The flag wide characters and their meanings are: - - The result of the conversion is left-justified within the field. (It is right-justified if - this flag is not specified.) - + The result of a signed conversion always begins with a plus or minus sign. (It - begins with a sign only when a negative value is converted if this flag is not - specified.)314) - space If the first wide character of a signed conversion is not a sign, or if a signed - conversion results in no wide characters, a space is prefixed to the result. If the - space and + flags both appear, the space flag is ignored. - # The result is converted to an ''alternative form''. For o conversion, it increases - the precision, if and only if necessary, to force the first digit of the result to be a - zero (if the value and precision are both 0, a single 0 is printed). For x (or X) - conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g, - - - 313) Note that 0 is taken as a flag, not as the beginning of a field width. - 314) The results of all floating conversions of a negative zero, and of negative values that round to zero, - include a minus sign. - -[page 400] - - and G conversions, the result of converting a floating-point number always - contains a decimal-point wide character, even if no digits follow it. (Normally, a - decimal-point wide character appears in the result of these conversions only if a - digit follows it.) For g and G conversions, trailing zeros are not removed from the - result. For other conversions, the behavior is undefined. - 0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros - (following any indication of sign or base) are used to pad to the field width rather - than performing space padding, except when converting an infinity or NaN. If the - 0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X - conversions, if a precision is specified, the 0 flag is ignored. For other - conversions, the behavior is undefined. -7 The length modifiers and their meanings are: - hh Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - signed char or unsigned char argument (the argument will have - been promoted according to the integer promotions, but its value shall be - converted to signed char or unsigned char before printing); or that - a following n conversion specifier applies to a pointer to a signed char - argument. - h Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - short int or unsigned short int argument (the argument will - have been promoted according to the integer promotions, but its value shall - be converted to short int or unsigned short int before printing); - or that a following n conversion specifier applies to a pointer to a short - int argument. - l (ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - long int or unsigned long int argument; that a following n - conversion specifier applies to a pointer to a long int argument; that a - following c conversion specifier applies to a wint_t argument; that a - following s conversion specifier applies to a pointer to a wchar_t - argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion - specifier. - ll (ell-ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - long long int or unsigned long long int argument; or that a - following n conversion specifier applies to a pointer to a long long int - argument. - j Specifies that a following d, i, o, u, x, or X conversion specifier applies to - an intmax_t or uintmax_t argument; or that a following n conversion - specifier applies to a pointer to an intmax_t argument. - -[page 401] - - z Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - size_t or the corresponding signed integer type argument; or that a - following n conversion specifier applies to a pointer to a signed integer type - corresponding to size_t argument. - t Specifies that a following d, i, o, u, x, or X conversion specifier applies to a - ptrdiff_t or the corresponding unsigned integer type argument; or that a - following n conversion specifier applies to a pointer to a ptrdiff_t - argument. - L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier - applies to a long double argument. - If a length modifier appears with any conversion specifier other than as specified above, - the behavior is undefined. -8 The conversion specifiers and their meanings are: - d,i The int argument is converted to signed decimal in the style [-]dddd. The - precision specifies the minimum number of digits to appear; if the value - being converted can be represented in fewer digits, it is expanded with - leading zeros. The default precision is 1. The result of converting a zero - value with a precision of zero is no wide characters. - o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned - decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the - letters abcdef are used for x conversion and the letters ABCDEF for X - conversion. The precision specifies the minimum number of digits to appear; - if the value being converted can be represented in fewer digits, it is expanded - with leading zeros. The default precision is 1. The result of converting a - zero value with a precision of zero is no wide characters. - f,F A double argument representing a floating-point number is converted to - decimal notation in the style [-]ddd.ddd, where the number of digits after - the decimal-point wide character is equal to the precision specification. If the - precision is missing, it is taken as 6; if the precision is zero and the # flag is - not specified, no decimal-point wide character appears. If a decimal-point - wide character appears, at least one digit appears before it. The value is - rounded to the appropriate number of digits. - A double argument representing an infinity is converted in one of the styles - [-]inf or [-]infinity -- which style is implementation-defined. A - double argument representing a NaN is converted in one of the styles - [-]nan or [-]nan(n-wchar-sequence) -- which style, and the meaning of - any n-wchar-sequence, is implementation-defined. The F conversion - specifier produces INF, INFINITY, or NAN instead of inf, infinity, or - -[page 402] - - nan, respectively.315) -e,E A double argument representing a floating-point number is converted in the - style [-]d.ddd e(+-)dd, where there is one digit (which is nonzero if the - argument is nonzero) before the decimal-point wide character and the number - of digits after it is equal to the precision; if the precision is missing, it is taken - as 6; if the precision is zero and the # flag is not specified, no decimal-point - wide character appears. The value is rounded to the appropriate number of - digits. The E conversion specifier produces a number with E instead of e - introducing the exponent. The exponent always contains at least two digits, - and only as many more digits as necessary to represent the exponent. If the - value is zero, the exponent is zero. - A double argument representing an infinity or NaN is converted in the style - of an f or F conversion specifier. -g,G A double argument representing a floating-point number is converted in - style f or e (or in style F or E in the case of a G conversion specifier), - depending on the value converted and the precision. Let P equal the - precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. - Then, if a conversion with style E would have an exponent of X: - -- if P > X >= -4, the conversion is with style f (or F) and precision - P - (X + 1). - -- otherwise, the conversion is with style e (or E) and precision P - 1. - Finally, unless the # flag is used, any trailing zeros are removed from the - fractional portion of the result and the decimal-point wide character is - removed if there is no fractional portion remaining. - A double argument representing an infinity or NaN is converted in the style - of an f or F conversion specifier. -a,A A double argument representing a floating-point number is converted in the - style [-]0xh.hhhh p(+-)d, where there is one hexadecimal digit (which is - nonzero if the argument is a normalized floating-point number and is - otherwise unspecified) before the decimal-point wide character316) and the - number of hexadecimal digits after it is equal to the precision; if the precision - is missing and FLT_RADIX is a power of 2, then the precision is sufficient - - -315) When applied to infinite and NaN values, the -, +, and space flag wide characters have their usual - meaning; the # and 0 flag wide characters have no effect. -316) Binary implementations can choose the hexadecimal digit to the left of the decimal-point wide - character so that subsequent digits align to nibble (4-bit) boundaries. - -[page 403] - - for an exact representation of the value; if the precision is missing and - FLT_RADIX is not a power of 2, then the precision is sufficient to - distinguish317) values of type double, except that trailing zeros may be - omitted; if the precision is zero and the # flag is not specified, no decimal- - point wide character appears. The letters abcdef are used for a conversion - and the letters ABCDEF for A conversion. The A conversion specifier - produces a number with X and P instead of x and p. The exponent always - contains at least one digit, and only as many more digits as necessary to - represent the decimal exponent of 2. If the value is zero, the exponent is - zero. - A double argument representing an infinity or NaN is converted in the style - of an f or F conversion specifier. -c If no l length modifier is present, the int argument is converted to a wide - character as if by calling btowc and the resulting wide character is written. - If an l length modifier is present, the wint_t argument is converted to - wchar_t and written. -s If no l length modifier is present, the argument shall be a pointer to the initial - element of a character array containing a multibyte character sequence - beginning in the initial shift state. Characters from the array are converted as - if by repeated calls to the mbrtowc function, with the conversion state - described by an mbstate_t object initialized to zero before the first - multibyte character is converted, and written up to (but not including) the - terminating null wide character. If the precision is specified, no more than - that many wide characters are written. If the precision is not specified or is - greater than the size of the converted array, the converted array shall contain a - null wide character. - If an l length modifier is present, the argument shall be a pointer to the initial - element of an array of wchar_t type. Wide characters from the array are - written up to (but not including) a terminating null wide character. If the - precision is specified, no more than that many wide characters are written. If - the precision is not specified or is greater than the size of the array, the array - shall contain a null wide character. -p The argument shall be a pointer to void. The value of the pointer is - converted to a sequence of printing wide characters, in an implementation- - -317) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is - FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p - might suffice depending on the implementation's scheme for determining the digit to the left of the - decimal-point wide character. - -[page 404] - - defined manner. - n The argument shall be a pointer to signed integer into which is written the - number of wide characters written to the output stream so far by this call to - fwprintf. No argument is converted, but one is consumed. If the - conversion specification includes any flags, a field width, or a precision, the - behavior is undefined. - % A % wide character is written. No argument is converted. The complete - conversion specification shall be %%. -9 If a conversion specification is invalid, the behavior is undefined.318) If any argument is - not the correct type for the corresponding conversion specification, the behavior is - undefined. -10 In no case does a nonexistent or small field width cause truncation of a field; if the result - of a conversion is wider than the field width, the field is expanded to contain the - conversion result. -11 For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded - to a hexadecimal floating number with the given precision. - Recommended practice -12 For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly - representable in the given precision, the result should be one of the two adjacent numbers - in hexadecimal floating style with the given precision, with the extra stipulation that the - error should have a correct sign for the current rounding direction. -13 For e, E, f, F, g, and G conversions, if the number of significant decimal digits is at most - DECIMAL_DIG, then the result should be correctly rounded.319) If the number of - significant decimal digits is more than DECIMAL_DIG but the source value is exactly - representable with DECIMAL_DIG digits, then the result should be an exact - representation with trailing zeros. Otherwise, the source value is bounded by two - adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value - of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that - the error should have a correct sign for the current rounding direction. - Returns -14 The fwprintf function returns the number of wide characters transmitted, or a negative - value if an output or encoding error occurred. - - 318) See ''future library directions'' (7.30.12). - 319) For binary-to-decimal conversion, the result format's values are the numbers representable with the - given format specifier. The number of significant digits is determined by the format specifier, and in - the case of fixed-point conversion by the source value as well. - -[page 405] - - Environmental limits -15 The number of wide characters that can be produced by any single conversion shall be at - least 4095. -16 EXAMPLE To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal - places: - #include - #include - #include - /* ... */ - wchar_t *weekday, *month; // pointers to wide strings - int day, hour, min; - fwprintf(stdout, L"%ls, %ls %d, %.2d:%.2d\n", - weekday, month, day, hour, min); - fwprintf(stdout, L"pi = %.5f\n", 4 * atan(1.0)); - - Forward references: the btowc function (7.28.6.1.1), the mbrtowc function - (7.28.6.3.2). - 7.28.2.2 The fwscanf function - Synopsis -1 #include - #include - int fwscanf(FILE * restrict stream, - const wchar_t * restrict format, ...); - Description -2 The fwscanf function reads input from the stream pointed to by stream, under - control of the wide string pointed to by format that specifies the admissible input - sequences and how they are to be converted for assignment, using subsequent arguments - as pointers to the objects to receive the converted input. If there are insufficient - arguments for the format, the behavior is undefined. If the format is exhausted while - arguments remain, the excess arguments are evaluated (as always) but are otherwise - ignored. -3 The format is composed of zero or more directives: one or more white-space wide - characters, an ordinary wide character (neither % nor a white-space wide character), or a - conversion specification. Each conversion specification is introduced by the wide - character %. After the %, the following appear in sequence: - -- An optional assignment-suppressing wide character *. - -- An optional decimal integer greater than zero that specifies the maximum field width - (in wide characters). - - - -[page 406] - - -- An optional length modifier that specifies the size of the receiving object. - -- A conversion specifier wide character that specifies the type of conversion to be - applied. -4 The fwscanf function executes each directive of the format in turn. When all directives - have been executed, or if a directive fails (as detailed below), the function returns. - Failures are described as input failures (due to the occurrence of an encoding error or the - unavailability of input characters), or matching failures (due to inappropriate input). -5 A directive composed of white-space wide character(s) is executed by reading input up to - the first non-white-space wide character (which remains unread), or until no more wide - characters can be read. -6 A directive that is an ordinary wide character is executed by reading the next wide - character of the stream. If that wide character differs from the directive, the directive - fails and the differing and subsequent wide characters remain unread. Similarly, if end- - of-file, an encoding error, or a read error prevents a wide character from being read, the - directive fails. -7 A directive that is a conversion specification defines a set of matching input sequences, as - described below for each specifier. A conversion specification is executed in the - following steps: -8 Input white-space wide characters (as specified by the iswspace function) are skipped, - unless the specification includes a [, c, or n specifier.320) -9 An input item is read from the stream, unless the specification includes an n specifier. An - input item is defined as the longest sequence of input wide characters which does not - exceed any specified field width and which is, or is a prefix of, a matching input - sequence.321) The first wide character, if any, after the input item remains unread. If the - length of the input item is zero, the execution of the directive fails; this condition is a - matching failure unless end-of-file, an encoding error, or a read error prevented input - from the stream, in which case it is an input failure. -10 Except in the case of a % specifier, the input item (or, in the case of a %n directive, the - count of input wide characters) is converted to a type appropriate to the conversion - specifier. If the input item is not a matching sequence, the execution of the directive fails: - this condition is a matching failure. Unless assignment suppression was indicated by a *, - the result of the conversion is placed in the object pointed to by the first argument - following the format argument that has not already received a conversion result. If this - - - 320) These white-space wide characters are not counted against a specified field width. - 321) fwscanf pushes back at most one input wide character onto the input stream. Therefore, some - sequences that are acceptable to wcstod, wcstol, etc., are unacceptable to fwscanf. - -[page 407] - - object does not have an appropriate type, or if the result of the conversion cannot be - represented in the object, the behavior is undefined. -11 The length modifiers and their meanings are: - hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to signed char or unsigned char. - h Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to short int or unsigned short - int. - l (ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to long int or unsigned long - int; that a following a, A, e, E, f, F, g, or G conversion specifier applies to - an argument with type pointer to double; or that a following c, s, or [ - conversion specifier applies to an argument with type pointer to wchar_t. - ll (ell-ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to long long int or unsigned - long long int. - j Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to intmax_t or uintmax_t. - z Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to size_t or the corresponding signed - integer type. - t Specifies that a following d, i, o, u, x, X, or n conversion specifier applies - to an argument with type pointer to ptrdiff_t or the corresponding - unsigned integer type. - L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier - applies to an argument with type pointer to long double. - If a length modifier appears with any conversion specifier other than as specified above, - the behavior is undefined. -12 The conversion specifiers and their meanings are: - d Matches an optionally signed decimal integer, whose format is the same as - expected for the subject sequence of the wcstol function with the value 10 - for the base argument. The corresponding argument shall be a pointer to - signed integer. - i Matches an optionally signed integer, whose format is the same as expected - for the subject sequence of the wcstol function with the value 0 for the - base argument. The corresponding argument shall be a pointer to signed - -[page 408] - - integer. -o Matches an optionally signed octal integer, whose format is the same as - expected for the subject sequence of the wcstoul function with the value 8 - for the base argument. The corresponding argument shall be a pointer to - unsigned integer. -u Matches an optionally signed decimal integer, whose format is the same as - expected for the subject sequence of the wcstoul function with the value 10 - for the base argument. The corresponding argument shall be a pointer to - unsigned integer. -x Matches an optionally signed hexadecimal integer, whose format is the same - as expected for the subject sequence of the wcstoul function with the value - 16 for the base argument. The corresponding argument shall be a pointer to - unsigned integer. -a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose - format is the same as expected for the subject sequence of the wcstod - function. The corresponding argument shall be a pointer to floating. -c Matches a sequence of wide characters of exactly the number specified by the - field width (1 if no field width is present in the directive). - If no l length modifier is present, characters from the input field are - converted as if by repeated calls to the wcrtomb function, with the - conversion state described by an mbstate_t object initialized to zero - before the first wide character is converted. The corresponding argument - shall be a pointer to the initial element of a character array large enough to - accept the sequence. No null character is added. - If an l length modifier is present, the corresponding argument shall be a - pointer to the initial element of an array of wchar_t large enough to accept - the sequence. No null wide character is added. -s Matches a sequence of non-white-space wide characters. - If no l length modifier is present, characters from the input field are - converted as if by repeated calls to the wcrtomb function, with the - conversion state described by an mbstate_t object initialized to zero - before the first wide character is converted. The corresponding argument - shall be a pointer to the initial element of a character array large enough to - accept the sequence and a terminating null character, which will be added - automatically. - If an l length modifier is present, the corresponding argument shall be a - pointer to the initial element of an array of wchar_t large enough to accept - -[page 409] - - the sequence and the terminating null wide character, which will be added - automatically. -[ Matches a nonempty sequence of wide characters from a set of expected - characters (the scanset). - If no l length modifier is present, characters from the input field are - converted as if by repeated calls to the wcrtomb function, with the - conversion state described by an mbstate_t object initialized to zero - before the first wide character is converted. The corresponding argument - shall be a pointer to the initial element of a character array large enough to - accept the sequence and a terminating null character, which will be added - automatically. - If an l length modifier is present, the corresponding argument shall be a - pointer to the initial element of an array of wchar_t large enough to accept - the sequence and the terminating null wide character, which will be added - automatically. - The conversion specifier includes all subsequent wide characters in the - format string, up to and including the matching right bracket (]). The wide - characters between the brackets (the scanlist) compose the scanset, unless the - wide character after the left bracket is a circumflex (^), in which case the - scanset contains all wide characters that do not appear in the scanlist between - the circumflex and the right bracket. If the conversion specifier begins with - [] or [^], the right bracket wide character is in the scanlist and the next - following right bracket wide character is the matching right bracket that ends - the specification; otherwise the first following right bracket wide character is - the one that ends the specification. If a - wide character is in the scanlist and - is not the first, nor the second where the first wide character is a ^, nor the - last character, the behavior is implementation-defined. -p Matches an implementation-defined set of sequences, which should be the - same as the set of sequences that may be produced by the %p conversion of - the fwprintf function. The corresponding argument shall be a pointer to a - pointer to void. The input item is converted to a pointer value in an - implementation-defined manner. If the input item is a value converted earlier - during the same program execution, the pointer that results shall compare - equal to that value; otherwise the behavior of the %p conversion is undefined. -n No input is consumed. The corresponding argument shall be a pointer to - signed integer into which is to be written the number of wide characters read - from the input stream so far by this call to the fwscanf function. Execution - of a %n directive does not increment the assignment count returned at the - completion of execution of the fwscanf function. No argument is -[page 410] - - converted, but one is consumed. If the conversion specification includes an - assignment-suppressing wide character or a field width, the behavior is - undefined. - % Matches a single % wide character; no conversion or assignment occurs. The - complete conversion specification shall be %%. -13 If a conversion specification is invalid, the behavior is undefined.322) -14 The conversion specifiers A, E, F, G, and X are also valid and behave the same as, - respectively, a, e, f, g, and x. -15 Trailing white space (including new-line wide characters) is left unread unless matched - by a directive. The success of literal matches and suppressed assignments is not directly - determinable other than via the %n directive. - Returns -16 The fwscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the function returns the - number of input items assigned, which can be fewer than provided for, or even zero, in - the event of an early matching failure. -17 EXAMPLE 1 The call: - #include - #include - /* ... */ - int n, i; float x; wchar_t name[50]; - n = fwscanf(stdin, L"%d%f%ls", &i, &x, name); - with the input line: - 25 54.32E-1 thompson - will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence - thompson\0. - -18 EXAMPLE 2 The call: - #include - #include - /* ... */ - int i; float x; double y; - fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y); - with input: - 56789 0123 56a72 - will assign to i the value 56 and to x the value 789.0, will skip past 0123, and will assign to y the value - 56.0. The next wide character read from the input stream will be a. - - - 322) See ''future library directions'' (7.30.12). - -[page 411] - - Forward references: the wcstod, wcstof, and wcstold functions (7.28.4.1.1), the - wcstol, wcstoll, wcstoul, and wcstoull functions (7.28.4.1.2), the wcrtomb - function (7.28.6.3.3). - 7.28.2.3 The swprintf function - Synopsis -1 #include - int swprintf(wchar_t * restrict s, - size_t n, - const wchar_t * restrict format, ...); - Description -2 The swprintf function is equivalent to fwprintf, except that the argument s - specifies an array of wide characters into which the generated output is to be written, - rather than written to a stream. No more than n wide characters are written, including a - terminating null wide character, which is always added (unless n is zero). - Returns -3 The swprintf function returns the number of wide characters written in the array, not - counting the terminating null wide character, or a negative value if an encoding error - occurred or if n or more wide characters were requested to be written. - 7.28.2.4 The swscanf function - Synopsis -1 #include - int swscanf(const wchar_t * restrict s, - const wchar_t * restrict format, ...); - Description -2 The swscanf function is equivalent to fwscanf, except that the argument s specifies a - wide string from which the input is to be obtained, rather than from a stream. Reaching - the end of the wide string is equivalent to encountering end-of-file for the fwscanf - function. - Returns -3 The swscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the swscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - - - - -[page 412] - - 7.28.2.5 The vfwprintf function - Synopsis -1 #include - #include - #include - int vfwprintf(FILE * restrict stream, - const wchar_t * restrict format, - va_list arg); - Description -2 The vfwprintf function is equivalent to fwprintf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vfwprintf function does not invoke the - va_end macro.323) - Returns -3 The vfwprintf function returns the number of wide characters transmitted, or a - negative value if an output or encoding error occurred. -4 EXAMPLE The following shows the use of the vfwprintf function in a general error-reporting - routine. - #include - #include - #include - void error(char *function_name, wchar_t *format, ...) - { - va_list args; - va_start(args, format); - // print out name of function causing error - fwprintf(stderr, L"ERROR in %s: ", function_name); - // print out remainder of message - vfwprintf(stderr, format, args); - va_end(args); - } - - - - - 323) As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf - invoke the va_arg macro, the value of arg after the return is indeterminate. - -[page 413] - - 7.28.2.6 The vfwscanf function - Synopsis -1 #include - #include - #include - int vfwscanf(FILE * restrict stream, - const wchar_t * restrict format, - va_list arg); - Description -2 The vfwscanf function is equivalent to fwscanf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vfwscanf function does not invoke the - va_end macro.323) - Returns -3 The vfwscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the vfwscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.28.2.7 The vswprintf function - Synopsis -1 #include - #include - int vswprintf(wchar_t * restrict s, - size_t n, - const wchar_t * restrict format, - va_list arg); - Description -2 The vswprintf function is equivalent to swprintf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vswprintf function does not invoke the - va_end macro.323) - Returns -3 The vswprintf function returns the number of wide characters written in the array, not - counting the terminating null wide character, or a negative value if an encoding error - occurred or if n or more wide characters were requested to be generated. - - -[page 414] - - 7.28.2.8 The vswscanf function - Synopsis -1 #include - #include - int vswscanf(const wchar_t * restrict s, - const wchar_t * restrict format, - va_list arg); - Description -2 The vswscanf function is equivalent to swscanf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vswscanf function does not invoke the - va_end macro.323) - Returns -3 The vswscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the vswscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.28.2.9 The vwprintf function - Synopsis -1 #include - #include - int vwprintf(const wchar_t * restrict format, - va_list arg); - Description -2 The vwprintf function is equivalent to wprintf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vwprintf function does not invoke the - va_end macro.323) - Returns -3 The vwprintf function returns the number of wide characters transmitted, or a negative - value if an output or encoding error occurred. - - - - -[page 415] - - 7.28.2.10 The vwscanf function - Synopsis -1 #include - #include - int vwscanf(const wchar_t * restrict format, - va_list arg); - Description -2 The vwscanf function is equivalent to wscanf, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vwscanf function does not invoke the - va_end macro.323) - Returns -3 The vwscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the vwscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.28.2.11 The wprintf function - Synopsis -1 #include - int wprintf(const wchar_t * restrict format, ...); - Description -2 The wprintf function is equivalent to fwprintf with the argument stdout - interposed before the arguments to wprintf. - Returns -3 The wprintf function returns the number of wide characters transmitted, or a negative - value if an output or encoding error occurred. - 7.28.2.12 The wscanf function - Synopsis -1 #include - int wscanf(const wchar_t * restrict format, ...); - Description -2 The wscanf function is equivalent to fwscanf with the argument stdin interposed - before the arguments to wscanf. - - -[page 416] - - Returns -3 The wscanf function returns the value of the macro EOF if an input failure occurs - before the first conversion (if any) has completed. Otherwise, the wscanf function - returns the number of input items assigned, which can be fewer than provided for, or even - zero, in the event of an early matching failure. - 7.28.3 Wide character input/output functions - 7.28.3.1 The fgetwc function - Synopsis -1 #include - #include - wint_t fgetwc(FILE *stream); - Description -2 If the end-of-file indicator for the input stream pointed to by stream is not set and a - next wide character is present, the fgetwc function obtains that wide character as a - wchar_t converted to a wint_t and advances the associated file position indicator for - the stream (if defined). - Returns -3 If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end- - of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise, - the fgetwc function returns the next wide character from the input stream pointed to by - stream. If a read error occurs, the error indicator for the stream is set and the fgetwc - function returns WEOF. If an encoding error occurs (including too few bytes), the value of - the macro EILSEQ is stored in errno and the fgetwc function returns WEOF.324) - 7.28.3.2 The fgetws function - Synopsis -1 #include - #include - wchar_t *fgetws(wchar_t * restrict s, - int n, FILE * restrict stream); - Description -2 The fgetws function reads at most one less than the number of wide characters - specified by n from the stream pointed to by stream into the array pointed to by s. No - - - 324) An end-of-file and a read error can be distinguished by use of the feof and ferror functions. - Also, errno will be set to EILSEQ by input/output functions only if an encoding error occurs. - -[page 417] - - additional wide characters are read after a new-line wide character (which is retained) or - after end-of-file. A null wide character is written immediately after the last wide - character read into the array. - Returns -3 The fgetws function returns s if successful. If end-of-file is encountered and no - characters have been read into the array, the contents of the array remain unchanged and a - null pointer is returned. If a read or encoding error occurs during the operation, the array - contents are indeterminate and a null pointer is returned. - 7.28.3.3 The fputwc function - Synopsis -1 #include - #include - wint_t fputwc(wchar_t c, FILE *stream); - Description -2 The fputwc function writes the wide character specified by c to the output stream - pointed to by stream, at the position indicated by the associated file position indicator - for the stream (if defined), and advances the indicator appropriately. If the file cannot - support positioning requests, or if the stream was opened with append mode, the - character is appended to the output stream. - Returns -3 The fputwc function returns the wide character written. If a write error occurs, the - error indicator for the stream is set and fputwc returns WEOF. If an encoding error - occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF. - 7.28.3.4 The fputws function - Synopsis -1 #include - #include - int fputws(const wchar_t * restrict s, - FILE * restrict stream); - Description -2 The fputws function writes the wide string pointed to by s to the stream pointed to by - stream. The terminating null wide character is not written. - Returns -3 The fputws function returns EOF if a write or encoding error occurs; otherwise, it - returns a nonnegative value. - -[page 418] - - 7.28.3.5 The fwide function - Synopsis -1 #include - #include - int fwide(FILE *stream, int mode); - Description -2 The fwide function determines the orientation of the stream pointed to by stream. If - mode is greater than zero, the function first attempts to make the stream wide oriented. If - mode is less than zero, the function first attempts to make the stream byte oriented.325) - Otherwise, mode is zero and the function does not alter the orientation of the stream. - Returns -3 The fwide function returns a value greater than zero if, after the call, the stream has - wide orientation, a value less than zero if the stream has byte orientation, or zero if the - stream has no orientation. - 7.28.3.6 The getwc function - Synopsis -1 #include - #include - wint_t getwc(FILE *stream); - Description -2 The getwc function is equivalent to fgetwc, except that if it is implemented as a - macro, it may evaluate stream more than once, so the argument should never be an - expression with side effects. - Returns -3 The getwc function returns the next wide character from the input stream pointed to by - stream, or WEOF. - 7.28.3.7 The getwchar function - Synopsis -1 #include - wint_t getwchar(void); - - - - - 325) If the orientation of the stream has already been determined, fwide does not change it. - -[page 419] - - Description -2 The getwchar function is equivalent to getwc with the argument stdin. - Returns -3 The getwchar function returns the next wide character from the input stream pointed to - by stdin, or WEOF. - 7.28.3.8 The putwc function - Synopsis -1 #include - #include - wint_t putwc(wchar_t c, FILE *stream); - Description -2 The putwc function is equivalent to fputwc, except that if it is implemented as a - macro, it may evaluate stream more than once, so that argument should never be an - expression with side effects. - Returns -3 The putwc function returns the wide character written, or WEOF. - 7.28.3.9 The putwchar function - Synopsis -1 #include - wint_t putwchar(wchar_t c); - Description -2 The putwchar function is equivalent to putwc with the second argument stdout. - Returns -3 The putwchar function returns the character written, or WEOF. - 7.28.3.10 The ungetwc function - Synopsis -1 #include - #include - wint_t ungetwc(wint_t c, FILE *stream); - Description -2 The ungetwc function pushes the wide character specified by c back onto the input - stream pointed to by stream. Pushed-back wide characters will be returned by - subsequent reads on that stream in the reverse order of their pushing. A successful - -[page 420] - - intervening call (with the stream pointed to by stream) to a file positioning function - (fseek, fsetpos, or rewind) discards any pushed-back wide characters for the - stream. The external storage corresponding to the stream is unchanged. -3 One wide character of pushback is guaranteed, even if the call to the ungetwc function - follows just after a call to a formatted wide character input function fwscanf, - vfwscanf, vwscanf, or wscanf. If the ungetwc function is called too many times - on the same stream without an intervening read or file positioning operation on that - stream, the operation may fail. -4 If the value of c equals that of the macro WEOF, the operation fails and the input stream is - unchanged. -5 A successful call to the ungetwc function clears the end-of-file indicator for the stream. - The value of the file position indicator for the stream after reading or discarding all - pushed-back wide characters is the same as it was before the wide characters were pushed - back. For a text or binary stream, the value of its file position indicator after a successful - call to the ungetwc function is unspecified until all pushed-back wide characters are - read or discarded. - Returns -6 The ungetwc function returns the wide character pushed back, or WEOF if the operation - fails. - 7.28.4 General wide string utilities -1 The header declares a number of functions useful for wide string - manipulation. Various methods are used for determining the lengths of the arrays, but in - all cases a wchar_t * argument points to the initial (lowest addressed) element of the - array. If an array is accessed beyond the end of an object, the behavior is undefined. -2 Where an argument declared as size_t n determines the length of the array for a - function, n can have the value zero on a call to that function. Unless explicitly stated - otherwise in the description of a particular function in this subclause, pointer arguments - on such a call shall still have valid values, as described in 7.1.4. On such a call, a - function that locates a wide character finds no occurrence, a function that compares two - wide character sequences returns zero, and a function that copies wide characters copies - zero wide characters. - - - - -[page 421] - - 7.28.4.1 Wide string numeric conversion functions - 7.28.4.1.1 The wcstod, wcstof, and wcstold functions - Synopsis -1 #include - double wcstod(const wchar_t * restrict nptr, - wchar_t ** restrict endptr); - float wcstof(const wchar_t * restrict nptr, - wchar_t ** restrict endptr); - long double wcstold(const wchar_t * restrict nptr, - wchar_t ** restrict endptr); - Description -2 The wcstod, wcstof, and wcstold functions convert the initial portion of the wide - string pointed to by nptr to double, float, and long double representation, - respectively. First, they decompose the input string into three parts: an initial, possibly - empty, sequence of white-space wide characters (as specified by the iswspace - function), a subject sequence resembling a floating-point constant or representing an - infinity or NaN; and a final wide string of one or more unrecognized wide characters, - including the terminating null wide character of the input wide string. Then, they attempt - to convert the subject sequence to a floating-point number, and return the result. -3 The expected form of the subject sequence is an optional plus or minus sign, then one of - the following: - -- a nonempty sequence of decimal digits optionally containing a decimal-point wide - character, then an optional exponent part as defined for the corresponding single-byte - characters in 6.4.4.2; - -- a 0x or 0X, then a nonempty sequence of hexadecimal digits optionally containing a - decimal-point wide character, then an optional binary exponent part as defined in - 6.4.4.2; - -- INF or INFINITY, or any other wide string equivalent except for case - -- NAN or NAN(n-wchar-sequenceopt), or any other wide string equivalent except for - case in the NAN part, where: - n-wchar-sequence: - digit - nondigit - n-wchar-sequence digit - n-wchar-sequence nondigit - The subject sequence is defined as the longest initial subsequence of the input wide - string, starting with the first non-white-space wide character, that is of the expected form. -[page 422] - - The subject sequence contains no wide characters if the input wide string is not of the - expected form. -4 If the subject sequence has the expected form for a floating-point number, the sequence of - wide characters starting with the first digit or the decimal-point wide character - (whichever occurs first) is interpreted as a floating constant according to the rules of - 6.4.4.2, except that the decimal-point wide character is used in place of a period, and that - if neither an exponent part nor a decimal-point wide character appears in a decimal - floating point number, or if a binary exponent part does not appear in a hexadecimal - floating point number, an exponent part of the appropriate type with value zero is - assumed to follow the last digit in the string. If the subject sequence begins with a minus - sign, the sequence is interpreted as negated.326) A wide character sequence INF or - INFINITY is interpreted as an infinity, if representable in the return type, else like a - floating constant that is too large for the range of the return type. A wide character - sequence NAN or NAN(n-wchar-sequenceopt) is interpreted as a quiet NaN, if supported - in the return type, else like a subject sequence part that does not have the expected form; - the meaning of the n-wchar sequences is implementation-defined.327) A pointer to the - final wide string is stored in the object pointed to by endptr, provided that endptr is - not a null pointer. -5 If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the - value resulting from the conversion is correctly rounded. -6 In other than the "C" locale, additional locale-specific subject sequence forms may be - accepted. -7 If the subject sequence is empty or does not have the expected form, no conversion is - performed; the value of nptr is stored in the object pointed to by endptr, provided - that endptr is not a null pointer. - Recommended practice -8 If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and - the result is not exactly representable, the result should be one of the two numbers in the - appropriate internal format that are adjacent to the hexadecimal floating source value, - with the extra stipulation that the error should have a correct sign for the current rounding - direction. - - - - 326) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by - negating the value resulting from converting the corresponding unsigned sequence (see F.5); the two - methods may yield different results if rounding is toward positive or negative infinity. In either case, - the functions honor the sign of zero if floating-point arithmetic supports signed zeros. - 327) An implementation may use the n-wchar sequence to determine extra information to be represented in - the NaN's significand. - -[page 423] - -9 If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in - ) significant digits, the result should be correctly rounded. If the subject - sequence D has the decimal form and more than DECIMAL_DIG significant digits, - consider the two bounding, adjacent decimal strings L and U, both having - DECIMAL_DIG significant digits, such that the values of L, D, and U satisfy L <= D <= U. - The result should be one of the (equal or adjacent) values that would be obtained by - correctly rounding L and U according to the current rounding direction, with the extra - stipulation that the error with respect to D should have a correct sign for the current - rounding direction.328) - Returns -10 The functions return the converted value, if any. If no conversion could be performed, - zero is returned. If the correct value overflows and default rounding is in effect (7.12.1), - plus or minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the - return type and sign of the value), and the value of the macro ERANGE is stored in - errno. If the result underflows (7.12.1), the functions return a value whose magnitude is - no greater than the smallest normalized positive number in the return type; whether - errno acquires the value ERANGE is implementation-defined. - - - - - 328) DECIMAL_DIG, defined in , should be sufficiently large that L and U will usually round - to the same internal floating value, but if not will round to adjacent values. - -[page 424] - - 7.28.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions - Synopsis -1 #include - long int wcstol( - const wchar_t * restrict nptr, - wchar_t ** restrict endptr, - int base); - long long int wcstoll( - const wchar_t * restrict nptr, - wchar_t ** restrict endptr, - int base); - unsigned long int wcstoul( - const wchar_t * restrict nptr, - wchar_t ** restrict endptr, - int base); - unsigned long long int wcstoull( - const wchar_t * restrict nptr, - wchar_t ** restrict endptr, - int base); - Description -2 The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial - portion of the wide string pointed to by nptr to long int, long long int, - unsigned long int, and unsigned long long int representation, - respectively. First, they decompose the input string into three parts: an initial, possibly - empty, sequence of white-space wide characters (as specified by the iswspace - function), a subject sequence resembling an integer represented in some radix determined - by the value of base, and a final wide string of one or more unrecognized wide - characters, including the terminating null wide character of the input wide string. Then, - they attempt to convert the subject sequence to an integer, and return the result. -3 If the value of base is zero, the expected form of the subject sequence is that of an - integer constant as described for the corresponding single-byte characters in 6.4.4.1, - optionally preceded by a plus or minus sign, but not including an integer suffix. If the - value of base is between 2 and 36 (inclusive), the expected form of the subject sequence - is a sequence of letters and digits representing an integer with the radix specified by - base, optionally preceded by a plus or minus sign, but not including an integer suffix. - The letters from a (or A) through z (or Z) are ascribed the values 10 through 35; only - letters and digits whose ascribed values are less than that of base are permitted. If the - value of base is 16, the wide characters 0x or 0X may optionally precede the sequence - of letters and digits, following the sign if present. - -[page 425] - -4 The subject sequence is defined as the longest initial subsequence of the input wide - string, starting with the first non-white-space wide character, that is of the expected form. - The subject sequence contains no wide characters if the input wide string is empty or - consists entirely of white space, or if the first non-white-space wide character is other - than a sign or a permissible letter or digit. -5 If the subject sequence has the expected form and the value of base is zero, the sequence - of wide characters starting with the first digit is interpreted as an integer constant - according to the rules of 6.4.4.1. If the subject sequence has the expected form and the - value of base is between 2 and 36, it is used as the base for conversion, ascribing to each - letter its value as given above. If the subject sequence begins with a minus sign, the value - resulting from the conversion is negated (in the return type). A pointer to the final wide - string is stored in the object pointed to by endptr, provided that endptr is not a null - pointer. -6 In other than the "C" locale, additional locale-specific subject sequence forms may be - accepted. -7 If the subject sequence is empty or does not have the expected form, no conversion is - performed; the value of nptr is stored in the object pointed to by endptr, provided - that endptr is not a null pointer. - Returns -8 The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted - value, if any. If no conversion could be performed, zero is returned. If the correct value - is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN, - LLONG_MAX, ULONG_MAX, or ULLONG_MAX is returned (according to the return type - sign of the value, if any), and the value of the macro ERANGE is stored in errno. - 7.28.4.2 Wide string copying functions - 7.28.4.2.1 The wcscpy function - Synopsis -1 #include - wchar_t *wcscpy(wchar_t * restrict s1, - const wchar_t * restrict s2); - Description -2 The wcscpy function copies the wide string pointed to by s2 (including the terminating - null wide character) into the array pointed to by s1. - Returns -3 The wcscpy function returns the value of s1. - - -[page 426] - - 7.28.4.2.2 The wcsncpy function - Synopsis -1 #include - wchar_t *wcsncpy(wchar_t * restrict s1, - const wchar_t * restrict s2, - size_t n); - Description -2 The wcsncpy function copies not more than n wide characters (those that follow a null - wide character are not copied) from the array pointed to by s2 to the array pointed to by - s1.329) -3 If the array pointed to by s2 is a wide string that is shorter than n wide characters, null - wide characters are appended to the copy in the array pointed to by s1, until n wide - characters in all have been written. - Returns -4 The wcsncpy function returns the value of s1. - 7.28.4.2.3 The wmemcpy function - Synopsis -1 #include - wchar_t *wmemcpy(wchar_t * restrict s1, - const wchar_t * restrict s2, - size_t n); - Description -2 The wmemcpy function copies n wide characters from the object pointed to by s2 to the - object pointed to by s1. - Returns -3 The wmemcpy function returns the value of s1. - - - - - 329) Thus, if there is no null wide character in the first n wide characters of the array pointed to by s2, the - result will not be null-terminated. - -[page 427] - - 7.28.4.2.4 The wmemmove function - Synopsis -1 #include - wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2, - size_t n); - Description -2 The wmemmove function copies n wide characters from the object pointed to by s2 to - the object pointed to by s1. Copying takes place as if the n wide characters from the - object pointed to by s2 are first copied into a temporary array of n wide characters that - does not overlap the objects pointed to by s1 or s2, and then the n wide characters from - the temporary array are copied into the object pointed to by s1. - Returns -3 The wmemmove function returns the value of s1. - 7.28.4.3 Wide string concatenation functions - 7.28.4.3.1 The wcscat function - Synopsis -1 #include - wchar_t *wcscat(wchar_t * restrict s1, - const wchar_t * restrict s2); - Description -2 The wcscat function appends a copy of the wide string pointed to by s2 (including the - terminating null wide character) to the end of the wide string pointed to by s1. The initial - wide character of s2 overwrites the null wide character at the end of s1. - Returns -3 The wcscat function returns the value of s1. - 7.28.4.3.2 The wcsncat function - Synopsis -1 #include - wchar_t *wcsncat(wchar_t * restrict s1, - const wchar_t * restrict s2, - size_t n); - Description -2 The wcsncat function appends not more than n wide characters (a null wide character - and those that follow it are not appended) from the array pointed to by s2 to the end of - -[page 428] - - the wide string pointed to by s1. The initial wide character of s2 overwrites the null - wide character at the end of s1. A terminating null wide character is always appended to - the result.330) - Returns -3 The wcsncat function returns the value of s1. - 7.28.4.4 Wide string comparison functions -1 Unless explicitly stated otherwise, the functions described in this subclause order two - wide characters the same way as two integers of the underlying integer type designated - by wchar_t. - 7.28.4.4.1 The wcscmp function - Synopsis -1 #include - int wcscmp(const wchar_t *s1, const wchar_t *s2); - Description -2 The wcscmp function compares the wide string pointed to by s1 to the wide string - pointed to by s2. - Returns -3 The wcscmp function returns an integer greater than, equal to, or less than zero, - accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the - wide string pointed to by s2. - 7.28.4.4.2 The wcscoll function - Synopsis -1 #include - int wcscoll(const wchar_t *s1, const wchar_t *s2); - Description -2 The wcscoll function compares the wide string pointed to by s1 to the wide string - pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the - current locale. - Returns -3 The wcscoll function returns an integer greater than, equal to, or less than zero, - accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the - - - 330) Thus, the maximum number of wide characters that can end up in the array pointed to by s1 is - wcslen(s1)+n+1. - -[page 429] - - wide string pointed to by s2 when both are interpreted as appropriate to the current - locale. - 7.28.4.4.3 The wcsncmp function - Synopsis -1 #include - int wcsncmp(const wchar_t *s1, const wchar_t *s2, - size_t n); - Description -2 The wcsncmp function compares not more than n wide characters (those that follow a - null wide character are not compared) from the array pointed to by s1 to the array - pointed to by s2. - Returns -3 The wcsncmp function returns an integer greater than, equal to, or less than zero, - accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal - to, or less than the possibly null-terminated array pointed to by s2. - 7.28.4.4.4 The wcsxfrm function - Synopsis -1 #include - size_t wcsxfrm(wchar_t * restrict s1, - const wchar_t * restrict s2, - size_t n); - Description -2 The wcsxfrm function transforms the wide string pointed to by s2 and places the - resulting wide string into the array pointed to by s1. The transformation is such that if - the wcscmp function is applied to two transformed wide strings, it returns a value greater - than, equal to, or less than zero, corresponding to the result of the wcscoll function - applied to the same two original wide strings. No more than n wide characters are placed - into the resulting array pointed to by s1, including the terminating null wide character. If - n is zero, s1 is permitted to be a null pointer. - Returns -3 The wcsxfrm function returns the length of the transformed wide string (not including - the terminating null wide character). If the value returned is n or greater, the contents of - the array pointed to by s1 are indeterminate. -4 EXAMPLE The value of the following expression is the length of the array needed to hold the - transformation of the wide string pointed to by s: - - -[page 430] - - 1 + wcsxfrm(NULL, s, 0) - - 7.28.4.4.5 The wmemcmp function - Synopsis -1 #include - int wmemcmp(const wchar_t *s1, const wchar_t *s2, - size_t n); - Description -2 The wmemcmp function compares the first n wide characters of the object pointed to by - s1 to the first n wide characters of the object pointed to by s2. - Returns -3 The wmemcmp function returns an integer greater than, equal to, or less than zero, - accordingly as the object pointed to by s1 is greater than, equal to, or less than the object - pointed to by s2. - 7.28.4.5 Wide string search functions - 7.28.4.5.1 The wcschr function - Synopsis -1 #include - wchar_t *wcschr(const wchar_t *s, wchar_t c); - Description -2 The wcschr function locates the first occurrence of c in the wide string pointed to by s. - The terminating null wide character is considered to be part of the wide string. - Returns -3 The wcschr function returns a pointer to the located wide character, or a null pointer if - the wide character does not occur in the wide string. - 7.28.4.5.2 The wcscspn function - Synopsis -1 #include - size_t wcscspn(const wchar_t *s1, const wchar_t *s2); - Description -2 The wcscspn function computes the length of the maximum initial segment of the wide - string pointed to by s1 which consists entirely of wide characters not from the wide - string pointed to by s2. - - - -[page 431] - - Returns -3 The wcscspn function returns the length of the segment. - 7.28.4.5.3 The wcspbrk function - Synopsis -1 #include - wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2); - Description -2 The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of - any wide character from the wide string pointed to by s2. - Returns -3 The wcspbrk function returns a pointer to the wide character in s1, or a null pointer if - no wide character from s2 occurs in s1. - 7.28.4.5.4 The wcsrchr function - Synopsis -1 #include - wchar_t *wcsrchr(const wchar_t *s, wchar_t c); - Description -2 The wcsrchr function locates the last occurrence of c in the wide string pointed to by - s. The terminating null wide character is considered to be part of the wide string. - Returns -3 The wcsrchr function returns a pointer to the wide character, or a null pointer if c does - not occur in the wide string. - 7.28.4.5.5 The wcsspn function - Synopsis -1 #include - size_t wcsspn(const wchar_t *s1, const wchar_t *s2); - Description -2 The wcsspn function computes the length of the maximum initial segment of the wide - string pointed to by s1 which consists entirely of wide characters from the wide string - pointed to by s2. - Returns -3 The wcsspn function returns the length of the segment. - - -[page 432] - - 7.28.4.5.6 The wcsstr function - Synopsis -1 #include - wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2); - Description -2 The wcsstr function locates the first occurrence in the wide string pointed to by s1 of - the sequence of wide characters (excluding the terminating null wide character) in the - wide string pointed to by s2. - Returns -3 The wcsstr function returns a pointer to the located wide string, or a null pointer if the - wide string is not found. If s2 points to a wide string with zero length, the function - returns s1. - 7.28.4.5.7 The wcstok function - Synopsis -1 #include - wchar_t *wcstok(wchar_t * restrict s1, - const wchar_t * restrict s2, - wchar_t ** restrict ptr); - Description -2 A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into - a sequence of tokens, each of which is delimited by a wide character from the wide string - pointed to by s2. The third argument points to a caller-provided wchar_t pointer into - which the wcstok function stores information necessary for it to continue scanning the - same wide string. -3 The first call in a sequence has a non-null first argument and stores an initial value in the - object pointed to by ptr. Subsequent calls in the sequence have a null first argument and - the object pointed to by ptr is required to have the value stored by the previous call in - the sequence, which is then updated. The separator wide string pointed to by s2 may be - different from call to call. -4 The first call in the sequence searches the wide string pointed to by s1 for the first wide - character that is not contained in the current separator wide string pointed to by s2. If no - such wide character is found, then there are no tokens in the wide string pointed to by s1 - and the wcstok function returns a null pointer. If such a wide character is found, it is - the start of the first token. -5 The wcstok function then searches from there for a wide character that is contained in - the current separator wide string. If no such wide character is found, the current token -[page 433] - - extends to the end of the wide string pointed to by s1, and subsequent searches in the - same wide string for a token return a null pointer. If such a wide character is found, it is - overwritten by a null wide character, which terminates the current token. -6 In all cases, the wcstok function stores sufficient information in the pointer pointed to - by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer - value for ptr, shall start searching just past the element overwritten by a null wide - character (if any). - Returns -7 The wcstok function returns a pointer to the first wide character of a token, or a null - pointer if there is no token. -8 EXAMPLE - #include - static wchar_t str1[] = L"?a???b,,,#c"; - static wchar_t str2[] = L"\t \t"; - wchar_t *t, *ptr1, *ptr2; - t = wcstok(str1, L"?", &ptr1); // t points to the token L"a" - t = wcstok(NULL, L",", &ptr1); // t points to the token L"??b" - t = wcstok(str2, L" \t", &ptr2); // t is a null pointer - t = wcstok(NULL, L"#,", &ptr1); // t points to the token L"c" - t = wcstok(NULL, L"?", &ptr1); // t is a null pointer - - 7.28.4.5.8 The wmemchr function - Synopsis -1 #include - wchar_t *wmemchr(const wchar_t *s, wchar_t c, - size_t n); - Description -2 The wmemchr function locates the first occurrence of c in the initial n wide characters of - the object pointed to by s. - Returns -3 The wmemchr function returns a pointer to the located wide character, or a null pointer if - the wide character does not occur in the object. - - - - -[page 434] - - 7.28.4.6 Miscellaneous functions - 7.28.4.6.1 The wcslen function - Synopsis -1 #include - size_t wcslen(const wchar_t *s); - Description -2 The wcslen function computes the length of the wide string pointed to by s. - Returns -3 The wcslen function returns the number of wide characters that precede the terminating - null wide character. - 7.28.4.6.2 The wmemset function - Synopsis -1 #include - wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n); - Description -2 The wmemset function copies the value of c into each of the first n wide characters of - the object pointed to by s. - Returns -3 The wmemset function returns the value of s. - 7.28.5 Wide character time conversion functions - 7.28.5.1 The wcsftime function - Synopsis -1 #include - #include - size_t wcsftime(wchar_t * restrict s, - size_t maxsize, - const wchar_t * restrict format, - const struct tm * restrict timeptr); - Description -2 The wcsftime function is equivalent to the strftime function, except that: - -- The argument s points to the initial element of an array of wide characters into which - the generated output is to be placed. - - -[page 435] - - -- The argument maxsize indicates the limiting number of wide characters. - -- The argument format is a wide string and the conversion specifiers are replaced by - corresponding sequences of wide characters. - -- The return value indicates the number of wide characters. - Returns -3 If the total number of resulting wide characters including the terminating null wide - character is not more than maxsize, the wcsftime function returns the number of - wide characters placed into the array pointed to by s not including the terminating null - wide character. Otherwise, zero is returned and the contents of the array are - indeterminate. - 7.28.6 Extended multibyte/wide character conversion utilities -1 The header declares an extended set of functions useful for conversion - between multibyte characters and wide characters. -2 Most of the following functions -- those that are listed as ''restartable'', 7.28.6.3 and - 7.28.6.4 -- take as a last argument a pointer to an object of type mbstate_t that is used - to describe the current conversion state from a particular multibyte character sequence to - a wide character sequence (or the reverse) under the rules of a particular setting for the - LC_CTYPE category of the current locale. -3 The initial conversion state corresponds, for a conversion in either direction, to the - beginning of a new multibyte character in the initial shift state. A zero-valued - mbstate_t object is (at least) one way to describe an initial conversion state. A zero- - valued mbstate_t object can be used to initiate conversion involving any multibyte - character sequence, in any LC_CTYPE category setting. If an mbstate_t object has - been altered by any of the functions described in this subclause, and is then used with a - different multibyte character sequence, or in the other conversion direction, or with a - different LC_CTYPE category setting than on earlier function calls, the behavior is - undefined.331) -4 On entry, each function takes the described conversion state (either internal or pointed to - by an argument) as current. The conversion state described by the referenced object is - altered as needed to track the shift state, and the position within a multibyte character, for - the associated multibyte character sequence. - - - - - 331) Thus, a particular mbstate_t object can be used, for example, with both the mbrtowc and - mbsrtowcs functions as long as they are used to step sequentially through the same multibyte - character string. - -[page 436] - - 7.28.6.1 Single-byte/wide character conversion functions - 7.28.6.1.1 The btowc function - Synopsis -1 #include * - wint_t btowc(int c); - Description -2 The btowc function determines whether c constitutes a valid single-byte character in the - initial shift state. - Returns -3 The btowc function returns WEOF if c has the value EOF or if (unsigned char)c - does not constitute a valid single-byte character in the initial shift state. Otherwise, it - returns the wide character representation of that character. - 7.28.6.1.2 The wctob function - Synopsis -1 #include * - int wctob(wint_t c); - Description -2 The wctob function determines whether c corresponds to a member of the extended - character set whose multibyte character representation is a single byte when in the initial - shift state. - Returns -3 The wctob function returns EOF if c does not correspond to a multibyte character with - length one in the initial shift state. Otherwise, it returns the single-byte representation of - that character as an unsigned char converted to an int. - 7.28.6.2 Conversion state functions - 7.28.6.2.1 The mbsinit function - Synopsis -1 #include - int mbsinit(const mbstate_t *ps); - Description -2 If ps is not a null pointer, the mbsinit function determines whether the referenced - mbstate_t object describes an initial conversion state. - - - -[page 437] - - Returns -3 The mbsinit function returns nonzero if ps is a null pointer or if the referenced object - describes an initial conversion state; otherwise, it returns zero. - 7.28.6.3 Restartable multibyte/wide character conversion functions -1 These functions differ from the corresponding multibyte character functions of 7.22.7 - (mblen, mbtowc, and wctomb) in that they have an extra parameter, ps, of type - pointer to mbstate_t that points to an object that can completely describe the current - conversion state of the associated multibyte character sequence. If ps is a null pointer, - each function uses its own internal mbstate_t object instead, which is initialized at - program startup to the initial conversion state; the functions are not required to avoid data - races in this case. The implementation behaves as if no library function calls these - functions with a null pointer for ps. -2 Also unlike their corresponding functions, the return value does not represent whether the - encoding is state-dependent. - 7.28.6.3.1 The mbrlen function - Synopsis -1 #include - size_t mbrlen(const char * restrict s, - size_t n, - mbstate_t * restrict ps); - Description -2 The mbrlen function is equivalent to the call: - mbrtowc(NULL, s, n, ps != NULL ? ps : &internal) - where internal is the mbstate_t object for the mbrlen function, except that the - expression designated by ps is evaluated only once. - Returns -3 The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2), - or (size_t)(-1). - Forward references: the mbrtowc function (7.28.6.3.2). - - - - -[page 438] - - 7.28.6.3.2 The mbrtowc function - Synopsis -1 #include - size_t mbrtowc(wchar_t * restrict pwc, - const char * restrict s, - size_t n, - mbstate_t * restrict ps); - Description -2 If s is a null pointer, the mbrtowc function is equivalent to the call: - mbrtowc(NULL, "", 1, ps) - In this case, the values of the parameters pwc and n are ignored. -3 If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with - the byte pointed to by s to determine the number of bytes needed to complete the next - multibyte character (including any shift sequences). If the function determines that the - next multibyte character is complete and valid, it determines the value of the - corresponding wide character and then, if pwc is not a null pointer, stores that value in - the object pointed to by pwc. If the corresponding wide character is the null wide - character, the resulting state described is the initial conversion state. - Returns -4 The mbrtowc function returns the first of the following that applies (given the current - conversion state): - 0 if the next n or fewer bytes complete the multibyte character that - corresponds to the null wide character (which is the value stored). - between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte - character (which is the value stored); the value returned is the number - of bytes that complete the multibyte character. - (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid) - multibyte character, and all n bytes have been processed (no value is - stored).332) - (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes - do not contribute to a complete and valid multibyte character (no - value is stored); the value of the macro EILSEQ is stored in errno, - and the conversion state is unspecified. - - 332) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a - sequence of redundant shift sequences (for implementations with state-dependent encodings). - -[page 439] - - 7.28.6.3.3 The wcrtomb function - Synopsis -1 #include - size_t wcrtomb(char * restrict s, - wchar_t wc, - mbstate_t * restrict ps); - Description -2 If s is a null pointer, the wcrtomb function is equivalent to the call - wcrtomb(buf, L'\0', ps) - where buf is an internal buffer. -3 If s is not a null pointer, the wcrtomb function determines the number of bytes needed - to represent the multibyte character that corresponds to the wide character given by wc - (including any shift sequences), and stores the multibyte character representation in the - array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If - wc is a null wide character, a null byte is stored, preceded by any shift sequence needed - to restore the initial shift state; the resulting state described is the initial conversion state. - Returns -4 The wcrtomb function returns the number of bytes stored in the array object (including - any shift sequences). When wc is not a valid wide character, an encoding error occurs: - the function stores the value of the macro EILSEQ in errno and returns - (size_t)(-1); the conversion state is unspecified. - 7.28.6.4 Restartable multibyte/wide string conversion functions -1 These functions differ from the corresponding multibyte string functions of 7.22.8 - (mbstowcs and wcstombs) in that they have an extra parameter, ps, of type pointer to - mbstate_t that points to an object that can completely describe the current conversion - state of the associated multibyte character sequence. If ps is a null pointer, each function - uses its own internal mbstate_t object instead, which is initialized at program startup - to the initial conversion state; the functions are not required to avoid data races in this - case. The implementation behaves as if no library function calls these functions with a - null pointer for ps. -2 Also unlike their corresponding functions, the conversion source parameter, src, has a - pointer-to-pointer type. When the function is storing the results of conversions (that is, - when dst is not a null pointer), the pointer object pointed to by this parameter is updated - to reflect the amount of the source processed by that invocation. - - - - -[page 440] - - 7.28.6.4.1 The mbsrtowcs function - Synopsis -1 #include - size_t mbsrtowcs(wchar_t * restrict dst, - const char ** restrict src, - size_t len, - mbstate_t * restrict ps); - Description -2 The mbsrtowcs function converts a sequence of multibyte characters that begins in the - conversion state described by the object pointed to by ps, from the array indirectly - pointed to by src into a sequence of corresponding wide characters. If dst is not a null - pointer, the converted characters are stored into the array pointed to by dst. Conversion - continues up to and including a terminating null character, which is also stored. - Conversion stops earlier in two cases: when a sequence of bytes is encountered that does - not form a valid multibyte character, or (if dst is not a null pointer) when len wide - characters have been stored into the array pointed to by dst.333) Each conversion takes - place as if by a call to the mbrtowc function. -3 If dst is not a null pointer, the pointer object pointed to by src is assigned either a null - pointer (if conversion stopped due to reaching a terminating null character) or the address - just past the last multibyte character converted (if any). If conversion stopped due to - reaching a terminating null character and if dst is not a null pointer, the resulting state - described is the initial conversion state. - Returns -4 If the input conversion encounters a sequence of bytes that do not form a valid multibyte - character, an encoding error occurs: the mbsrtowcs function stores the value of the - macro EILSEQ in errno and returns (size_t)(-1); the conversion state is - unspecified. Otherwise, it returns the number of multibyte characters successfully - converted, not including the terminating null character (if any). - - - - - 333) Thus, the value of len is ignored if dst is a null pointer. - -[page 441] - - 7.28.6.4.2 The wcsrtombs function - Synopsis -1 #include - size_t wcsrtombs(char * restrict dst, - const wchar_t ** restrict src, - size_t len, - mbstate_t * restrict ps); - Description -2 The wcsrtombs function converts a sequence of wide characters from the array - indirectly pointed to by src into a sequence of corresponding multibyte characters that - begins in the conversion state described by the object pointed to by ps. If dst is not a - null pointer, the converted characters are then stored into the array pointed to by dst. - Conversion continues up to and including a terminating null wide character, which is also - stored. Conversion stops earlier in two cases: when a wide character is reached that does - not correspond to a valid multibyte character, or (if dst is not a null pointer) when the - next multibyte character would exceed the limit of len total bytes to be stored into the - array pointed to by dst. Each conversion takes place as if by a call to the wcrtomb - function.334) -3 If dst is not a null pointer, the pointer object pointed to by src is assigned either a null - pointer (if conversion stopped due to reaching a terminating null wide character) or the - address just past the last wide character converted (if any). If conversion stopped due to - reaching a terminating null wide character, the resulting state described is the initial - conversion state. - Returns -4 If conversion stops because a wide character is reached that does not correspond to a - valid multibyte character, an encoding error occurs: the wcsrtombs function stores the - value of the macro EILSEQ in errno and returns (size_t)(-1); the conversion - state is unspecified. Otherwise, it returns the number of bytes in the resulting multibyte - character sequence, not including the terminating null character (if any). - - - - - 334) If conversion stops because a terminating null wide character has been reached, the bytes stored - include those necessary to reach the initial shift state immediately before the null byte. - -[page 442] - - 7.29 Wide character classification and mapping utilities - 7.29.1 Introduction -1 The header defines one macro, and declares three data types and many - functions.335) -2 The types declared are - wint_t - described in 7.28.1; - wctrans_t - which is a scalar type that can hold values which represent locale-specific character - mappings; and - wctype_t - which is a scalar type that can hold values which represent locale-specific character - classifications. -3 The macro defined is WEOF (described in 7.28.1). -4 The functions declared are grouped as follows: - -- Functions that provide wide character classification; - -- Extensible functions that provide wide character classification; - -- Functions that provide wide character case mapping; - -- Extensible functions that provide wide character mapping. -5 For all functions described in this subclause that accept an argument of type wint_t, the - value shall be representable as a wchar_t or shall equal the value of the macro WEOF. If - this argument has any other value, the behavior is undefined. -6 The behavior of these functions is affected by the LC_CTYPE category of the current - locale. - - - - - 335) See ''future library directions'' (7.30.13). - -[page 443] - - 7.29.2 Wide character classification utilities -1 The header declares several functions useful for classifying wide - characters. -2 The term printing wide character refers to a member of a locale-specific set of wide - characters, each of which occupies at least one printing position on a display device. The - term control wide character refers to a member of a locale-specific set of wide characters - that are not printing wide characters. - 7.29.2.1 Wide character classification functions -1 The functions in this subclause return nonzero (true) if and only if the value of the - argument wc conforms to that in the description of the function. -2 Each of the following functions returns true for each wide character that corresponds (as - if by a call to the wctob function) to a single-byte character for which the corresponding - character classification function from 7.4.1 returns true, except that the iswgraph and - iswpunct functions may differ with respect to wide characters other than L' ' that are - both printing and white-space wide characters.336) - Forward references: the wctob function (7.28.6.1.2). - 7.29.2.1.1 The iswalnum function - Synopsis -1 #include - int iswalnum(wint_t wc); - Description -2 The iswalnum function tests for any wide character for which iswalpha or - iswdigit is true. - 7.29.2.1.2 The iswalpha function - Synopsis -1 #include - int iswalpha(wint_t wc); - Description -2 The iswalpha function tests for any wide character for which iswupper or - iswlower is true, or any wide character that is one of a locale-specific set of alphabetic - - 336) For example, if the expression isalpha(wctob(wc)) evaluates to true, then the call - iswalpha(wc) also returns true. But, if the expression isgraph(wctob(wc)) evaluates to true - (which cannot occur for wc == L' ' of course), then either iswgraph(wc) or iswprint(wc) - && iswspace(wc) is true, but not both. - -[page 444] - - wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace - is true.337) - 7.29.2.1.3 The iswblank function - Synopsis -1 #include - int iswblank(wint_t wc); - Description -2 The iswblank function tests for any wide character that is a standard blank wide - character or is one of a locale-specific set of wide characters for which iswspace is true - and that is used to separate words within a line of text. The standard blank wide - characters are the following: space (L' '), and horizontal tab (L'\t'). In the "C" - locale, iswblank returns true only for the standard blank characters. - 7.29.2.1.4 The iswcntrl function - Synopsis -1 #include - int iswcntrl(wint_t wc); - Description -2 The iswcntrl function tests for any control wide character. - 7.29.2.1.5 The iswdigit function - Synopsis -1 #include - int iswdigit(wint_t wc); - Description -2 The iswdigit function tests for any wide character that corresponds to a decimal-digit - character (as defined in 5.2.1). - 7.29.2.1.6 The iswgraph function - Synopsis -1 #include - int iswgraph(wint_t wc); - - - - - 337) The functions iswlower and iswupper test true or false separately for each of these additional - wide characters; all four combinations are possible. - -[page 445] - - Description -2 The iswgraph function tests for any wide character for which iswprint is true and - iswspace is false.338) - 7.29.2.1.7 The iswlower function - Synopsis -1 #include - int iswlower(wint_t wc); - Description -2 The iswlower function tests for any wide character that corresponds to a lowercase - letter or is one of a locale-specific set of wide characters for which none of iswcntrl, - iswdigit, iswpunct, or iswspace is true. - 7.29.2.1.8 The iswprint function - Synopsis -1 #include - int iswprint(wint_t wc); - Description -2 The iswprint function tests for any printing wide character. - 7.29.2.1.9 The iswpunct function - Synopsis -1 #include - int iswpunct(wint_t wc); - Description -2 The iswpunct function tests for any printing wide character that is one of a locale- - specific set of punctuation wide characters for which neither iswspace nor iswalnum - is true.338) - 7.29.2.1.10 The iswspace function - Synopsis -1 #include - int iswspace(wint_t wc); - - - - 338) Note that the behavior of the iswgraph and iswpunct functions may differ from their - corresponding functions in 7.4.1 with respect to printing, white-space, single-byte execution - characters other than ' '. - -[page 446] - - Description -2 The iswspace function tests for any wide character that corresponds to a locale-specific - set of white-space wide characters for which none of iswalnum, iswgraph, or - iswpunct is true. - 7.29.2.1.11 The iswupper function - Synopsis -1 #include - int iswupper(wint_t wc); - Description -2 The iswupper function tests for any wide character that corresponds to an uppercase - letter or is one of a locale-specific set of wide characters for which none of iswcntrl, - iswdigit, iswpunct, or iswspace is true. - 7.29.2.1.12 The iswxdigit function - Synopsis -1 #include - int iswxdigit(wint_t wc); - Description -2 The iswxdigit function tests for any wide character that corresponds to a - hexadecimal-digit character (as defined in 6.4.4.1). - 7.29.2.2 Extensible wide character classification functions -1 The functions wctype and iswctype provide extensible wide character classification - as well as testing equivalent to that performed by the functions described in the previous - subclause (7.29.2.1). - 7.29.2.2.1 The iswctype function - Synopsis -1 #include - int iswctype(wint_t wc, wctype_t desc); - Description -2 The iswctype function determines whether the wide character wc has the property - described by desc. The current setting of the LC_CTYPE category shall be the same as - during the call to wctype that returned the value desc. -3 Each of the following expressions has a truth-value equivalent to the call to the wide - character classification function (7.29.2.1) in the comment that follows the expression: - - -[page 447] - - iswctype(wc, wctype("alnum")) // iswalnum(wc) - iswctype(wc, wctype("alpha")) // iswalpha(wc) - iswctype(wc, wctype("blank")) // iswblank(wc) - iswctype(wc, wctype("cntrl")) // iswcntrl(wc) - iswctype(wc, wctype("digit")) // iswdigit(wc) - iswctype(wc, wctype("graph")) // iswgraph(wc) - iswctype(wc, wctype("lower")) // iswlower(wc) - iswctype(wc, wctype("print")) // iswprint(wc) - iswctype(wc, wctype("punct")) // iswpunct(wc) - iswctype(wc, wctype("space")) // iswspace(wc) - iswctype(wc, wctype("upper")) // iswupper(wc) - iswctype(wc, wctype("xdigit")) // iswxdigit(wc) - Returns -4 The iswctype function returns nonzero (true) if and only if the value of the wide - character wc has the property described by desc. - Forward references: the wctype function (7.29.2.2.2). - 7.29.2.2.2 The wctype function - Synopsis -1 #include - wctype_t wctype(const char *property); - Description -2 The wctype function constructs a value with type wctype_t that describes a class of - wide characters identified by the string argument property. -3 The strings listed in the description of the iswctype function shall be valid in all - locales as property arguments to the wctype function. - Returns -4 If property identifies a valid class of wide characters according to the LC_CTYPE - category of the current locale, the wctype function returns a nonzero value that is valid - as the second argument to the iswctype function; otherwise, it returns zero. - - - - -[page 448] - - 7.29.3 Wide character case mapping utilities -1 The header declares several functions useful for mapping wide characters. - 7.29.3.1 Wide character case mapping functions - 7.29.3.1.1 The towlower function - Synopsis -1 #include - wint_t towlower(wint_t wc); - Description -2 The towlower function converts an uppercase letter to a corresponding lowercase letter. - Returns -3 If the argument is a wide character for which iswupper is true and there are one or - more corresponding wide characters, as specified by the current locale, for which - iswlower is true, the towlower function returns one of the corresponding wide - characters (always the same one for any given locale); otherwise, the argument is - returned unchanged. - 7.29.3.1.2 The towupper function - Synopsis -1 #include - wint_t towupper(wint_t wc); - Description -2 The towupper function converts a lowercase letter to a corresponding uppercase letter. - Returns -3 If the argument is a wide character for which iswlower is true and there are one or - more corresponding wide characters, as specified by the current locale, for which - iswupper is true, the towupper function returns one of the corresponding wide - characters (always the same one for any given locale); otherwise, the argument is - returned unchanged. - 7.29.3.2 Extensible wide character case mapping functions -1 The functions wctrans and towctrans provide extensible wide character mapping as - well as case mapping equivalent to that performed by the functions described in the - previous subclause (7.29.3.1). - - - - -[page 449] - - 7.29.3.2.1 The towctrans function - Synopsis -1 #include - wint_t towctrans(wint_t wc, wctrans_t desc); - Description -2 The towctrans function maps the wide character wc using the mapping described by - desc. The current setting of the LC_CTYPE category shall be the same as during the call - to wctrans that returned the value desc. -3 Each of the following expressions behaves the same as the call to the wide character case - mapping function (7.29.3.1) in the comment that follows the expression: - towctrans(wc, wctrans("tolower")) // towlower(wc) - towctrans(wc, wctrans("toupper")) // towupper(wc) - Returns -4 The towctrans function returns the mapped value of wc using the mapping described - by desc. - 7.29.3.2.2 The wctrans function - Synopsis -1 #include - wctrans_t wctrans(const char *property); - Description -2 The wctrans function constructs a value with type wctrans_t that describes a - mapping between wide characters identified by the string argument property. -3 The strings listed in the description of the towctrans function shall be valid in all - locales as property arguments to the wctrans function. - Returns -4 If property identifies a valid mapping of wide characters according to the LC_CTYPE - category of the current locale, the wctrans function returns a nonzero value that is valid - as the second argument to the towctrans function; otherwise, it returns zero. - - - - -[page 450] - - 7.30 Future library directions -1 The following names are grouped under individual headers for convenience. All external - names described below are reserved no matter what headers are included by the program. - 7.30.1 Complex arithmetic -1 The function names - cerf cexpm1 clog2 - cerfc clog10 clgamma - cexp2 clog1p ctgamma - and the same names suffixed with f or l may be added to the declarations in the - header. - 7.30.2 Character handling -1 Function names that begin with either is or to, and a lowercase letter may be added to - the declarations in the header. - 7.30.3 Errors -1 Macros that begin with E and a digit or E and an uppercase letter may be added to the - declarations in the header. - 7.30.4 Format conversion of integer types -1 Macro names beginning with PRI or SCN followed by any lowercase letter or X may be - added to the macros defined in the header. - 7.30.5 Localization -1 Macros that begin with LC_ and an uppercase letter may be added to the definitions in - the header. - 7.30.6 Signal handling -1 Macros that begin with either SIG and an uppercase letter or SIG_ and an uppercase - letter may be added to the definitions in the header. - 7.30.7 Boolean type and values -1 The ability to undefine and perhaps then redefine the macros bool, true, and false is - an obsolescent feature. - 7.30.8 Integer types -1 Typedef names beginning with int or uint and ending with _t may be added to the - types defined in the header. Macro names beginning with INT or UINT - and ending with _MAX, _MIN, or _C may be added to the macros defined in the - header. - -[page 451] - - 7.30.9 Input/output -1 Lowercase letters may be added to the conversion specifiers and length modifiers in - fprintf and fscanf. Other characters may be used in extensions. -2 The use of ungetc on a binary stream where the file position indicator is zero prior to - the call is an obsolescent feature. - 7.30.10 General utilities -1 Function names that begin with str and a lowercase letter may be added to the - declarations in the header. - 7.30.11 String handling -1 Function names that begin with str, mem, or wcs and a lowercase letter may be added - to the declarations in the header. - 7.30.12 Extended multibyte and wide character utilities -1 Function names that begin with wcs and a lowercase letter may be added to the - declarations in the header. -2 Lowercase letters may be added to the conversion specifiers and length modifiers in - fwprintf and fwscanf. Other characters may be used in extensions. - 7.30.13 Wide character classification and mapping utilities - -1 Function names that begin with is or to and a lowercase letter may be added to the - declarations in the header. - - - - -[page 452] - - Annex A - (informative) - Language syntax summary -1 NOTE The notation is described in 6.1. - - A.1 Lexical grammar - A.1.1 Lexical elements - (6.4) token: - keyword - identifier - constant - string-literal - punctuator - (6.4) preprocessing-token: - header-name - identifier - pp-number - character-constant - string-literal - punctuator - each non-white-space character that cannot be one of the above - - - - -[page 453] - -A.1.2 Keywords -(6.4.1) keyword: one of - alignof goto union - auto if unsigned - break inline void - case int volatile - char long while - const register _Alignas - continue restrict _Atomic - default return _Bool - do short _Complex - double signed _Generic - else sizeof _Imaginary - enum static _Noreturn - extern struct _Static_assert - float switch _Thread_local - for typedef -A.1.3 Identifiers -(6.4.2.1) identifier: - identifier-nondigit - identifier identifier-nondigit - identifier digit -(6.4.2.1) identifier-nondigit: - nondigit - universal-character-name - other implementation-defined characters -(6.4.2.1) nondigit: one of - _ a b c d e f g h i j k l m - n o p q r s t u v w x y z - A B C D E F G H I J K L M - N O P Q R S T U V W X Y Z -(6.4.2.1) digit: one of - 0 1 2 3 4 5 6 7 8 9 - - - - -[page 454] - -A.1.4 Universal character names -(6.4.3) universal-character-name: - \u hex-quad - \U hex-quad hex-quad -(6.4.3) hex-quad: - hexadecimal-digit hexadecimal-digit - hexadecimal-digit hexadecimal-digit -A.1.5 Constants -(6.4.4) constant: - integer-constant - floating-constant - enumeration-constant - character-constant -(6.4.4.1) integer-constant: - decimal-constant integer-suffixopt - octal-constant integer-suffixopt - hexadecimal-constant integer-suffixopt -(6.4.4.1) decimal-constant: - nonzero-digit - decimal-constant digit -(6.4.4.1) octal-constant: - 0 - octal-constant octal-digit -(6.4.4.1) hexadecimal-constant: - hexadecimal-prefix hexadecimal-digit - hexadecimal-constant hexadecimal-digit -(6.4.4.1) hexadecimal-prefix: one of - 0x 0X -(6.4.4.1) nonzero-digit: one of - 1 2 3 4 5 6 7 8 9 -(6.4.4.1) octal-digit: one of - 0 1 2 3 4 5 6 7 - - - - -[page 455] - -(6.4.4.1) hexadecimal-digit: one of - 0 1 2 3 4 5 6 7 8 9 - a b c d e f - A B C D E F -(6.4.4.1) integer-suffix: - unsigned-suffix long-suffixopt - unsigned-suffix long-long-suffix - long-suffix unsigned-suffixopt - long-long-suffix unsigned-suffixopt -(6.4.4.1) unsigned-suffix: one of - u U -(6.4.4.1) long-suffix: one of - l L -(6.4.4.1) long-long-suffix: one of - ll LL -(6.4.4.2) floating-constant: - decimal-floating-constant - hexadecimal-floating-constant -(6.4.4.2) decimal-floating-constant: - fractional-constant exponent-partopt floating-suffixopt - digit-sequence exponent-part floating-suffixopt -(6.4.4.2) hexadecimal-floating-constant: - hexadecimal-prefix hexadecimal-fractional-constant - binary-exponent-part floating-suffixopt - hexadecimal-prefix hexadecimal-digit-sequence - binary-exponent-part floating-suffixopt -(6.4.4.2) fractional-constant: - digit-sequenceopt . digit-sequence - digit-sequence . -(6.4.4.2) exponent-part: - e signopt digit-sequence - E signopt digit-sequence -(6.4.4.2) sign: one of - + - - - - -[page 456] - -(6.4.4.2) digit-sequence: - digit - digit-sequence digit -(6.4.4.2) hexadecimal-fractional-constant: - hexadecimal-digit-sequenceopt . - hexadecimal-digit-sequence - hexadecimal-digit-sequence . -(6.4.4.2) binary-exponent-part: - p signopt digit-sequence - P signopt digit-sequence -(6.4.4.2) hexadecimal-digit-sequence: - hexadecimal-digit - hexadecimal-digit-sequence hexadecimal-digit -(6.4.4.2) floating-suffix: one of - f l F L -(6.4.4.3) enumeration-constant: - identifier -(6.4.4.4) character-constant: - ' c-char-sequence ' - L' c-char-sequence ' - u' c-char-sequence ' - U' c-char-sequence ' -(6.4.4.4) c-char-sequence: - c-char - c-char-sequence c-char -(6.4.4.4) c-char: - any member of the source character set except - the single-quote ', backslash \, or new-line character - escape-sequence -(6.4.4.4) escape-sequence: - simple-escape-sequence - octal-escape-sequence - hexadecimal-escape-sequence - universal-character-name - - - - -[page 457] - -(6.4.4.4) simple-escape-sequence: one of - \' \" \? \\ - \a \b \f \n \r \t \v -(6.4.4.4) octal-escape-sequence: - \ octal-digit - \ octal-digit octal-digit - \ octal-digit octal-digit octal-digit -(6.4.4.4) hexadecimal-escape-sequence: - \x hexadecimal-digit - hexadecimal-escape-sequence hexadecimal-digit -A.1.6 String literals -(6.4.5) string-literal: - encoding-prefixopt " s-char-sequenceopt " -(6.4.5) encoding-prefix: - u8 - u - U - L -(6.4.5) s-char-sequence: - s-char - s-char-sequence s-char -(6.4.5) s-char: - any member of the source character set except - the double-quote ", backslash \, or new-line character - escape-sequence -A.1.7 Punctuators -(6.4.6) punctuator: one of - [ ] ( ) { } . -> - ++ -- & * + - ~ ! - / % << >> < > <= >= == != ^ | && || - ? : ; ... - = *= /= %= += -= <<= >>= &= ^= |= - , # ## - <: :> <% %> %: %:%: - - - - -[page 458] - -A.1.8 Header names -(6.4.7) header-name: - < h-char-sequence > - " q-char-sequence " -(6.4.7) h-char-sequence: - h-char - h-char-sequence h-char -(6.4.7) h-char: - any member of the source character set except - the new-line character and > -(6.4.7) q-char-sequence: - q-char - q-char-sequence q-char -(6.4.7) q-char: - any member of the source character set except - the new-line character and " -A.1.9 Preprocessing numbers -(6.4.8) pp-number: - digit - . digit - pp-number digit - pp-number identifier-nondigit - pp-number e sign - pp-number E sign - pp-number p sign - pp-number P sign - pp-number . - - - - -[page 459] - -A.2 Phrase structure grammar -A.2.1 Expressions -(6.5.1) primary-expression: - identifier - constant - string-literal - ( expression ) - generic-selection -(6.5.1.1) generic-selection: - _Generic ( assignment-expression , generic-assoc-list ) -(6.5.1.1) generic-assoc-list: - generic-association - generic-assoc-list , generic-association -(6.5.1.1) generic-association: - type-name : assignment-expression - default : assignment-expression -(6.5.2) postfix-expression: - primary-expression - postfix-expression [ expression ] - postfix-expression ( argument-expression-listopt ) - postfix-expression . identifier - postfix-expression -> identifier - postfix-expression ++ - postfix-expression -- - ( type-name ) { initializer-list } - ( type-name ) { initializer-list , } -(6.5.2) argument-expression-list: - assignment-expression - argument-expression-list , assignment-expression -(6.5.3) unary-expression: - postfix-expression - ++ unary-expression - -- unary-expression - unary-operator cast-expression - sizeof unary-expression - sizeof ( type-name ) - alignof ( type-name ) - -[page 460] - -(6.5.3) unary-operator: one of - & * + - ~ ! -(6.5.4) cast-expression: - unary-expression - ( type-name ) cast-expression -(6.5.5) multiplicative-expression: - cast-expression - multiplicative-expression * cast-expression - multiplicative-expression / cast-expression - multiplicative-expression % cast-expression -(6.5.6) additive-expression: - multiplicative-expression - additive-expression + multiplicative-expression - additive-expression - multiplicative-expression -(6.5.7) shift-expression: - additive-expression - shift-expression << additive-expression - shift-expression >> additive-expression -(6.5.8) relational-expression: - shift-expression - relational-expression < shift-expression - relational-expression > shift-expression - relational-expression <= shift-expression - relational-expression >= shift-expression -(6.5.9) equality-expression: - relational-expression - equality-expression == relational-expression - equality-expression != relational-expression -(6.5.10) AND-expression: - equality-expression - AND-expression & equality-expression -(6.5.11) exclusive-OR-expression: - AND-expression - exclusive-OR-expression ^ AND-expression - - - - -[page 461] - -(6.5.12) inclusive-OR-expression: - exclusive-OR-expression - inclusive-OR-expression | exclusive-OR-expression -(6.5.13) logical-AND-expression: - inclusive-OR-expression - logical-AND-expression && inclusive-OR-expression -(6.5.14) logical-OR-expression: - logical-AND-expression - logical-OR-expression || logical-AND-expression -(6.5.15) conditional-expression: - logical-OR-expression - logical-OR-expression ? expression : conditional-expression -(6.5.16) assignment-expression: - conditional-expression - unary-expression assignment-operator assignment-expression -(6.5.16) assignment-operator: one of - = *= /= %= += -= <<= >>= &= ^= |= -(6.5.17) expression: - assignment-expression - expression , assignment-expression -(6.6) constant-expression: - conditional-expression -A.2.2 Declarations -(6.7) declaration: - declaration-specifiers init-declarator-listopt ; - static_assert-declaration * -(6.7) declaration-specifiers: - storage-class-specifier declaration-specifiersopt - type-specifier declaration-specifiersopt - type-qualifier declaration-specifiersopt - function-specifier declaration-specifiersopt - alignment-specifier declaration-specifiersopt -(6.7) init-declarator-list: - init-declarator - init-declarator-list , init-declarator - - -[page 462] - -(6.7) init-declarator: - declarator - declarator = initializer -(6.7.1) storage-class-specifier: - typedef - extern - static - _Thread_local - auto - register -(6.7.2) type-specifier: - void - char - short - int - long - float - double - signed - unsigned - _Bool - _Complex - _Atomic ( type-name ) - struct-or-union-specifier - enum-specifier - typedef-name -(6.7.2.1) struct-or-union-specifier: - struct-or-union identifieropt { struct-declaration-list } - struct-or-union identifier -(6.7.2.1) struct-or-union: - struct - union -(6.7.2.1) struct-declaration-list: - struct-declaration - struct-declaration-list struct-declaration -(6.7.2.1) struct-declaration: - specifier-qualifier-list struct-declarator-listopt ; - static_assert-declaration - -[page 463] - -(6.7.2.1) specifier-qualifier-list: - type-specifier specifier-qualifier-listopt - type-qualifier specifier-qualifier-listopt -(6.7.2.1) struct-declarator-list: - struct-declarator - struct-declarator-list , struct-declarator -(6.7.2.1) struct-declarator: - declarator - declaratoropt : constant-expression -(6.7.2.2) enum-specifier: - enum identifieropt { enumerator-list } - enum identifieropt { enumerator-list , } - enum identifier -(6.7.2.2) enumerator-list: - enumerator - enumerator-list , enumerator -(6.7.2.2) enumerator: - enumeration-constant - enumeration-constant = constant-expression -(6.7.3) type-qualifier: - const - restrict - volatile - _Atomic -(6.7.4) function-specifier: - inline - _Noreturn -(6.7.5) alignment-specifier: - _Alignas ( type-name ) - _Alignas ( constant-expression ) -(6.7.6) declarator: - pointeropt direct-declarator - - - - -[page 464] - -(6.7.6) direct-declarator: - identifier - ( declarator ) - direct-declarator [ type-qualifier-listopt assignment-expressionopt ] - direct-declarator [ static type-qualifier-listopt assignment-expression ] - direct-declarator [ type-qualifier-list static assignment-expression ] - direct-declarator [ type-qualifier-listopt * ] - direct-declarator ( parameter-type-list ) - direct-declarator ( identifier-listopt ) -(6.7.6) pointer: - * type-qualifier-listopt - * type-qualifier-listopt pointer -(6.7.6) type-qualifier-list: - type-qualifier - type-qualifier-list type-qualifier -(6.7.6) parameter-type-list: - parameter-list - parameter-list , ... -(6.7.6) parameter-list: - parameter-declaration - parameter-list , parameter-declaration -(6.7.6) parameter-declaration: - declaration-specifiers declarator - declaration-specifiers abstract-declaratoropt -(6.7.6) identifier-list: - identifier - identifier-list , identifier -(6.7.7) type-name: - specifier-qualifier-list abstract-declaratoropt -(6.7.7) abstract-declarator: - pointer - pointeropt direct-abstract-declarator - - - - -[page 465] - -(6.7.7) direct-abstract-declarator: - ( abstract-declarator ) - direct-abstract-declaratoropt [ type-qualifier-listopt - assignment-expressionopt ] - direct-abstract-declaratoropt [ static type-qualifier-listopt - assignment-expression ] - direct-abstract-declaratoropt [ type-qualifier-list static - assignment-expression ] - direct-abstract-declaratoropt [ * ] - direct-abstract-declaratoropt ( parameter-type-listopt ) -(6.7.8) typedef-name: - identifier -(6.7.9) initializer: - assignment-expression - { initializer-list } - { initializer-list , } -(6.7.9) initializer-list: - designationopt initializer - initializer-list , designationopt initializer -(6.7.9) designation: - designator-list = -(6.7.9) designator-list: - designator - designator-list designator -(6.7.9) designator: - [ constant-expression ] - . identifier -(6.7.10) static_assert-declaration: - _Static_assert ( constant-expression , string-literal ) ; - - - - -[page 466] - -A.2.3 Statements -(6.8) statement: - labeled-statement - compound-statement - expression-statement - selection-statement - iteration-statement - jump-statement -(6.8.1) labeled-statement: - identifier : statement - case constant-expression : statement - default : statement -(6.8.2) compound-statement: - { block-item-listopt } -(6.8.2) block-item-list: - block-item - block-item-list block-item -(6.8.2) block-item: - declaration - statement -(6.8.3) expression-statement: - expressionopt ; -(6.8.4) selection-statement: - if ( expression ) statement - if ( expression ) statement else statement - switch ( expression ) statement -(6.8.5) iteration-statement: - while ( expression ) statement - do statement while ( expression ) ; - for ( expressionopt ; expressionopt ; expressionopt ) statement - for ( declaration expressionopt ; expressionopt ) statement -(6.8.6) jump-statement: - goto identifier ; - continue ; - break ; - return expressionopt ; - -[page 467] - -A.2.4 External definitions -(6.9) translation-unit: - external-declaration - translation-unit external-declaration -(6.9) external-declaration: - function-definition - declaration -(6.9.1) function-definition: - declaration-specifiers declarator declaration-listopt compound-statement -(6.9.1) declaration-list: - declaration - declaration-list declaration -A.3 Preprocessing directives -(6.10) preprocessing-file: - groupopt -(6.10) group: - group-part - group group-part -(6.10) group-part: - if-section - control-line - text-line - # non-directive -(6.10) if-section: - if-group elif-groupsopt else-groupopt endif-line -(6.10) if-group: - # if constant-expression new-line groupopt - # ifdef identifier new-line groupopt - # ifndef identifier new-line groupopt -(6.10) elif-groups: - elif-group - elif-groups elif-group -(6.10) elif-group: - # elif constant-expression new-line groupopt - - -[page 468] - -(6.10) else-group: - # else new-line groupopt -(6.10) endif-line: - # endif new-line -(6.10) control-line: - # include pp-tokens new-line - # define identifier replacement-list new-line - # define identifier lparen identifier-listopt ) - replacement-list new-line - # define identifier lparen ... ) replacement-list new-line - # define identifier lparen identifier-list , ... ) - replacement-list new-line - # undef identifier new-line - # line pp-tokens new-line - # error pp-tokensopt new-line - # pragma pp-tokensopt new-line - # new-line -(6.10) text-line: - pp-tokensopt new-line -(6.10) non-directive: - pp-tokens new-line -(6.10) lparen: - a ( character not immediately preceded by white-space -(6.10) replacement-list: - pp-tokensopt -(6.10) pp-tokens: - preprocessing-token - pp-tokens preprocessing-token -(6.10) new-line: - the new-line character - - - - -[page 469] - - Annex B - (informative) - Library summary -B.1 Diagnostics - NDEBUG - static_assert - void assert(scalar expression); -B.2 Complex - __STDC_NO_COMPLEX__ imaginary - complex _Imaginary_I - _Complex_I I - #pragma STDC CX_LIMITED_RANGE on-off-switch - double complex cacos(double complex z); - float complex cacosf(float complex z); - long double complex cacosl(long double complex z); - double complex casin(double complex z); - float complex casinf(float complex z); - long double complex casinl(long double complex z); - double complex catan(double complex z); - float complex catanf(float complex z); - long double complex catanl(long double complex z); - double complex ccos(double complex z); - float complex ccosf(float complex z); - long double complex ccosl(long double complex z); - double complex csin(double complex z); - float complex csinf(float complex z); - long double complex csinl(long double complex z); - double complex ctan(double complex z); - float complex ctanf(float complex z); - long double complex ctanl(long double complex z); - double complex cacosh(double complex z); - float complex cacoshf(float complex z); - long double complex cacoshl(long double complex z); - double complex casinh(double complex z); - float complex casinhf(float complex z); - long double complex casinhl(long double complex z); - -[page 470] - - double complex catanh(double complex z); - float complex catanhf(float complex z); - long double complex catanhl(long double complex z); - double complex ccosh(double complex z); - float complex ccoshf(float complex z); - long double complex ccoshl(long double complex z); - double complex csinh(double complex z); - float complex csinhf(float complex z); - long double complex csinhl(long double complex z); - double complex ctanh(double complex z); - float complex ctanhf(float complex z); - long double complex ctanhl(long double complex z); - double complex cexp(double complex z); - float complex cexpf(float complex z); - long double complex cexpl(long double complex z); - double complex clog(double complex z); - float complex clogf(float complex z); - long double complex clogl(long double complex z); - double cabs(double complex z); - float cabsf(float complex z); - long double cabsl(long double complex z); - double complex cpow(double complex x, double complex y); - float complex cpowf(float complex x, float complex y); - long double complex cpowl(long double complex x, - long double complex y); - double complex csqrt(double complex z); - float complex csqrtf(float complex z); - long double complex csqrtl(long double complex z); - double carg(double complex z); - float cargf(float complex z); - long double cargl(long double complex z); - double cimag(double complex z); - float cimagf(float complex z); - long double cimagl(long double complex z); - double complex CMPLX(double x, double y); - float complex CMPLXF(float x, float y); - long double complex CMPLXL(long double x, long double y); - double complex conj(double complex z); - float complex conjf(float complex z); - long double complex conjl(long double complex z); - double complex cproj(double complex z); - -[page 471] - - float complex cprojf(float complex z); - long double complex cprojl(long double complex z); - double creal(double complex z); - float crealf(float complex z); - long double creall(long double complex z); -B.3 Character handling - int isalnum(int c); - int isalpha(int c); - int isblank(int c); - int iscntrl(int c); - int isdigit(int c); - int isgraph(int c); - int islower(int c); - int isprint(int c); - int ispunct(int c); - int isspace(int c); - int isupper(int c); - int isxdigit(int c); - int tolower(int c); - int toupper(int c); -B.4 Errors - EDOM EILSEQ ERANGE errno - __STDC_WANT_LIB_EXT1__ - errno_t -B.5 Floating-point environment - fenv_t FE_OVERFLOW FE_TOWARDZERO - fexcept_t FE_UNDERFLOW FE_UPWARD - FE_DIVBYZERO FE_ALL_EXCEPT FE_DFL_ENV - FE_INEXACT FE_DOWNWARD - FE_INVALID FE_TONEAREST - #pragma STDC FENV_ACCESS on-off-switch - int feclearexcept(int excepts); - int fegetexceptflag(fexcept_t *flagp, int excepts); - int feraiseexcept(int excepts); - int fesetexceptflag(const fexcept_t *flagp, - int excepts); - int fetestexcept(int excepts); - -[page 472] - - int fegetround(void); - int fesetround(int round); - int fegetenv(fenv_t *envp); - int feholdexcept(fenv_t *envp); - int fesetenv(const fenv_t *envp); - int feupdateenv(const fenv_t *envp); -B.6 Characteristics of floating types - FLT_ROUNDS DBL_DIG FLT_MAX - FLT_EVAL_METHOD LDBL_DIG DBL_MAX - FLT_HAS_SUBNORM FLT_MIN_EXP LDBL_MAX - DBL_HAS_SUBNORM DBL_MIN_EXP FLT_EPSILON - LDBL_HAS_SUBNORM LDBL_MIN_EXP DBL_EPSILON - FLT_RADIX FLT_MIN_10_EXP LDBL_EPSILON - FLT_MANT_DIG DBL_MIN_10_EXP FLT_MIN - DBL_MANT_DIG LDBL_MIN_10_EXP DBL_MIN - LDBL_MANT_DIG FLT_MAX_EXP LDBL_MIN - FLT_DECIMAL_DIG DBL_MAX_EXP FLT_TRUE_MIN - DBL_DECIMAL_DIG LDBL_MAX_EXP DBL_TRUE_MIN - LDBL_DECIMAL_DIG FLT_MAX_10_EXP LDBL_TRUE_MIN - DECIMAL_DIG DBL_MAX_10_EXP - FLT_DIG LDBL_MAX_10_EXP -B.7 Format conversion of integer types - imaxdiv_t - PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR - PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR - PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR - PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR - PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR - PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR - SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR - SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR - SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR - SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR - SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR - intmax_t imaxabs(intmax_t j); - imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom); - intmax_t strtoimax(const char * restrict nptr, - char ** restrict endptr, int base); - -[page 473] - - uintmax_t strtoumax(const char * restrict nptr, - char ** restrict endptr, int base); - intmax_t wcstoimax(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - uintmax_t wcstoumax(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); -B.8 Alternative spellings - and bitor not_eq xor - and_eq compl or xor_eq - bitand not or_eq -B.9 Sizes of integer types - CHAR_BIT CHAR_MAX INT_MIN ULONG_MAX - SCHAR_MIN MB_LEN_MAX INT_MAX LLONG_MIN - SCHAR_MAX SHRT_MIN UINT_MAX LLONG_MAX - UCHAR_MAX SHRT_MAX LONG_MIN ULLONG_MAX - CHAR_MIN USHRT_MAX LONG_MAX -B.10 Localization - struct lconv LC_ALL LC_CTYPE LC_NUMERIC - NULL LC_COLLATE LC_MONETARY LC_TIME - char *setlocale(int category, const char *locale); - struct lconv *localeconv(void); -B.11 Mathematics - float_t FP_INFINITE FP_FAST_FMAL - double_t FP_NAN FP_ILOGB0 - HUGE_VAL FP_NORMAL FP_ILOGBNAN - HUGE_VALF FP_SUBNORMAL MATH_ERRNO - HUGE_VALL FP_ZERO MATH_ERREXCEPT - INFINITY FP_FAST_FMA math_errhandling - NAN FP_FAST_FMAF - #pragma STDC FP_CONTRACT on-off-switch - int fpclassify(real-floating x); - int isfinite(real-floating x); - int isinf(real-floating x); - int isnan(real-floating x); - int isnormal(real-floating x); - int signbit(real-floating x); -[page 474] - - double acos(double x); - float acosf(float x); - long double acosl(long double x); - double asin(double x); - float asinf(float x); - long double asinl(long double x); - double atan(double x); - float atanf(float x); - long double atanl(long double x); - double atan2(double y, double x); - float atan2f(float y, float x); - long double atan2l(long double y, long double x); - double cos(double x); - float cosf(float x); - long double cosl(long double x); - double sin(double x); - float sinf(float x); - long double sinl(long double x); - double tan(double x); - float tanf(float x); - long double tanl(long double x); - double acosh(double x); - float acoshf(float x); - long double acoshl(long double x); - double asinh(double x); - float asinhf(float x); - long double asinhl(long double x); - double atanh(double x); - float atanhf(float x); - long double atanhl(long double x); - double cosh(double x); - float coshf(float x); - long double coshl(long double x); - double sinh(double x); - float sinhf(float x); - long double sinhl(long double x); - double tanh(double x); - float tanhf(float x); - long double tanhl(long double x); - double exp(double x); - float expf(float x); - -[page 475] - - long double expl(long double x); - double exp2(double x); - float exp2f(float x); - long double exp2l(long double x); - double expm1(double x); - float expm1f(float x); - long double expm1l(long double x); - double frexp(double value, int *exp); - float frexpf(float value, int *exp); - long double frexpl(long double value, int *exp); - int ilogb(double x); - int ilogbf(float x); - int ilogbl(long double x); - double ldexp(double x, int exp); - float ldexpf(float x, int exp); - long double ldexpl(long double x, int exp); - double log(double x); - float logf(float x); - long double logl(long double x); - double log10(double x); - float log10f(float x); - long double log10l(long double x); - double log1p(double x); - float log1pf(float x); - long double log1pl(long double x); - double log2(double x); - float log2f(float x); - long double log2l(long double x); - double logb(double x); - float logbf(float x); - long double logbl(long double x); - double modf(double value, double *iptr); - float modff(float value, float *iptr); - long double modfl(long double value, long double *iptr); - double scalbn(double x, int n); - float scalbnf(float x, int n); - long double scalbnl(long double x, int n); - double scalbln(double x, long int n); - float scalblnf(float x, long int n); - long double scalblnl(long double x, long int n); - double cbrt(double x); - -[page 476] - - float cbrtf(float x); - long double cbrtl(long double x); - double fabs(double x); - float fabsf(float x); - long double fabsl(long double x); - double hypot(double x, double y); - float hypotf(float x, float y); - long double hypotl(long double x, long double y); - double pow(double x, double y); - float powf(float x, float y); - long double powl(long double x, long double y); - double sqrt(double x); - float sqrtf(float x); - long double sqrtl(long double x); - double erf(double x); - float erff(float x); - long double erfl(long double x); - double erfc(double x); - float erfcf(float x); - long double erfcl(long double x); - double lgamma(double x); - float lgammaf(float x); - long double lgammal(long double x); - double tgamma(double x); - float tgammaf(float x); - long double tgammal(long double x); - double ceil(double x); - float ceilf(float x); - long double ceill(long double x); - double floor(double x); - float floorf(float x); - long double floorl(long double x); - double nearbyint(double x); - float nearbyintf(float x); - long double nearbyintl(long double x); - double rint(double x); - float rintf(float x); - long double rintl(long double x); - long int lrint(double x); - long int lrintf(float x); - long int lrintl(long double x); - -[page 477] - - long long int llrint(double x); - long long int llrintf(float x); - long long int llrintl(long double x); - double round(double x); - float roundf(float x); - long double roundl(long double x); - long int lround(double x); - long int lroundf(float x); - long int lroundl(long double x); - long long int llround(double x); - long long int llroundf(float x); - long long int llroundl(long double x); - double trunc(double x); - float truncf(float x); - long double truncl(long double x); - double fmod(double x, double y); - float fmodf(float x, float y); - long double fmodl(long double x, long double y); - double remainder(double x, double y); - float remainderf(float x, float y); - long double remainderl(long double x, long double y); - double remquo(double x, double y, int *quo); - float remquof(float x, float y, int *quo); - long double remquol(long double x, long double y, - int *quo); - double copysign(double x, double y); - float copysignf(float x, float y); - long double copysignl(long double x, long double y); - double nan(const char *tagp); - float nanf(const char *tagp); - long double nanl(const char *tagp); - double nextafter(double x, double y); - float nextafterf(float x, float y); - long double nextafterl(long double x, long double y); - double nexttoward(double x, long double y); - float nexttowardf(float x, long double y); - long double nexttowardl(long double x, long double y); - double fdim(double x, double y); - float fdimf(float x, float y); - long double fdiml(long double x, long double y); - double fmax(double x, double y); - -[page 478] - - float fmaxf(float x, float y); - long double fmaxl(long double x, long double y); - double fmin(double x, double y); - float fminf(float x, float y); - long double fminl(long double x, long double y); - double fma(double x, double y, double z); - float fmaf(float x, float y, float z); - long double fmal(long double x, long double y, - long double z); - int isgreater(real-floating x, real-floating y); - int isgreaterequal(real-floating x, real-floating y); - int isless(real-floating x, real-floating y); - int islessequal(real-floating x, real-floating y); - int islessgreater(real-floating x, real-floating y); - int isunordered(real-floating x, real-floating y); -B.12 Nonlocal jumps - jmp_buf - int setjmp(jmp_buf env); - _Noreturn void longjmp(jmp_buf env, int val); -B.13 Signal handling - sig_atomic_t SIG_IGN SIGILL SIGTERM - SIG_DFL SIGABRT SIGINT - SIG_ERR SIGFPE SIGSEGV - void (*signal(int sig, void (*func)(int)))(int); - int raise(int sig); - - - - -[page 479] - -B.14 Alignment - alignas - __alignas_is_defined -B.15 Variable arguments - va_list - type va_arg(va_list ap, type); - void va_copy(va_list dest, va_list src); - void va_end(va_list ap); - void va_start(va_list ap, parmN); -B.16 Atomics - ATOMIC_CHAR_LOCK_FREE atomic_uint - ATOMIC_CHAR16_T_LOCK_FREE atomic_long - ATOMIC_CHAR32_T_LOCK_FREE atomic_ulong - ATOMIC_WCHAR_T_LOCK_FREE atomic_llong - ATOMIC_SHORT_LOCK_FREE atomic_ullong - ATOMIC_INT_LOCK_FREE atomic_char16_t - ATOMIC_LONG_LOCK_FREE atomic_char32_t - ATOMIC_LLONG_LOCK_FREE atomic_wchar_t - ATOMIC_ADDRESS_LOCK_FREE atomic_int_least8_t - ATOMIC_FLAG_INIT atomic_uint_least8_t - memory_order atomic_int_least16_t - atomic_flag atomic_uint_least16_t - atomic_bool atomic_int_least32_t - atomic_address atomic_uint_least32_t - memory_order_relaxed atomic_int_least64_t - memory_order_consume atomic_uint_least64_t - memory_order_acquire atomic_int_fast8_t - memory_order_release atomic_uint_fast8_t - memory_order_acq_rel atomic_int_fast16_t - memory_order_seq_cst atomic_uint_fast16_t - atomic_char atomic_int_fast32_t - atomic_schar atomic_uint_fast32_t - atomic_uchar atomic_int_fast64_t - atomic_short atomic_uint_fast64_t - atomic_ushort atomic_intptr_t - atomic_int atomic_uintptr_t - - - -[page 480] - - atomic_size_t atomic_intmax_t - atomic_ptrdiff_t atomic_uintmax_t - #define ATOMIC_VAR_INIT(C value) - void atomic_init(volatile A *obj, C value); - type kill_dependency(type y); - void atomic_thread_fence(memory_order order); - void atomic_signal_fence(memory_order order); - _Bool atomic_is_lock_free(atomic_type const volatile *obj); - void atomic_store(volatile A *object, C desired); - void atomic_store_explicit(volatile A *object, - C desired, memory_order order); - C atomic_load(volatile A *object); - C atomic_load_explicit(volatile A *object, - memory_order order); - C atomic_exchange(volatile A *object, C desired); - C atomic_exchange_explicit(volatile A *object, - C desired, memory_order order); - _Bool atomic_compare_exchange_strong(volatile A *object, - C *expected, C desired); - _Bool atomic_compare_exchange_strong_explicit( - volatile A *object, C *expected, C desired, - memory_order success, memory_order failure); - _Bool atomic_compare_exchange_weak(volatile A *object, - C *expected, C desired); - _Bool atomic_compare_exchange_weak_explicit( - volatile A *object, C *expected, C desired, - memory_order success, memory_order failure); - C atomic_fetch_key(volatile A *object, M operand); - C atomic_fetch_key_explicit(volatile A *object, - M operand, memory_order order); - bool atomic_flag_test_and_set( - volatile atomic_flag *object); - bool atomic_flag_test_and_set_explicit( - volatile atomic_flag *object, memory_order order); - void atomic_flag_clear(volatile atomic_flag *object); - void atomic_flag_clear_explicit( - volatile atomic_flag *object, memory_order order); - - - - -[page 481] - -B.17 Boolean type and values - bool - true - false - __bool_true_false_are_defined -B.18 Common definitions - ptrdiff_t max_align_t NULL - size_t wchar_t - offsetof(type, member-designator) - __STDC_WANT_LIB_EXT1__ - rsize_t -B.19 Integer types - intN_t INT_LEASTN_MIN PTRDIFF_MAX - uintN_t INT_LEASTN_MAX SIG_ATOMIC_MIN - int_leastN_t UINT_LEASTN_MAX SIG_ATOMIC_MAX - uint_leastN_t INT_FASTN_MIN SIZE_MAX - int_fastN_t INT_FASTN_MAX WCHAR_MIN - uint_fastN_t UINT_FASTN_MAX WCHAR_MAX - intptr_t INTPTR_MIN WINT_MIN - uintptr_t INTPTR_MAX WINT_MAX - intmax_t UINTPTR_MAX INTN_C(value) - uintmax_t INTMAX_MIN UINTN_C(value) - INTN_MIN INTMAX_MAX INTMAX_C(value) - INTN_MAX UINTMAX_MAX UINTMAX_C(value) - UINTN_MAX PTRDIFF_MIN - __STDC_WANT_LIB_EXT1__ - RSIZE_MAX - - - - -[page 482] - -B.20 Input/output - size_t _IOLBF FILENAME_MAX TMP_MAX - FILE _IONBF L_tmpnam stderr - fpos_t BUFSIZ SEEK_CUR stdin - NULL EOF SEEK_END stdout - _IOFBF FOPEN_MAX SEEK_SET - int remove(const char *filename); - int rename(const char *old, const char *new); - FILE *tmpfile(void); - char *tmpnam(char *s); - int fclose(FILE *stream); - int fflush(FILE *stream); - FILE *fopen(const char * restrict filename, - const char * restrict mode); - FILE *freopen(const char * restrict filename, - const char * restrict mode, - FILE * restrict stream); - void setbuf(FILE * restrict stream, - char * restrict buf); - int setvbuf(FILE * restrict stream, - char * restrict buf, - int mode, size_t size); - int fprintf(FILE * restrict stream, - const char * restrict format, ...); - int fscanf(FILE * restrict stream, - const char * restrict format, ...); - int printf(const char * restrict format, ...); - int scanf(const char * restrict format, ...); - int snprintf(char * restrict s, size_t n, - const char * restrict format, ...); - int sprintf(char * restrict s, - const char * restrict format, ...); - int sscanf(const char * restrict s, - const char * restrict format, ...); - int vfprintf(FILE * restrict stream, - const char * restrict format, va_list arg); - int vfscanf(FILE * restrict stream, - const char * restrict format, va_list arg); - int vprintf(const char * restrict format, va_list arg); - int vscanf(const char * restrict format, va_list arg); - -[page 483] - - int vsnprintf(char * restrict s, size_t n, - const char * restrict format, va_list arg); - int vsprintf(char * restrict s, - const char * restrict format, va_list arg); - int vsscanf(const char * restrict s, - const char * restrict format, va_list arg); - int fgetc(FILE *stream); - char *fgets(char * restrict s, int n, - FILE * restrict stream); - int fputc(int c, FILE *stream); - int fputs(const char * restrict s, - FILE * restrict stream); - int getc(FILE *stream); - int getchar(void); - int putc(int c, FILE *stream); - int putchar(int c); - int puts(const char *s); - int ungetc(int c, FILE *stream); - size_t fread(void * restrict ptr, - size_t size, size_t nmemb, - FILE * restrict stream); - size_t fwrite(const void * restrict ptr, - size_t size, size_t nmemb, - FILE * restrict stream); - int fgetpos(FILE * restrict stream, - fpos_t * restrict pos); - int fseek(FILE *stream, long int offset, int whence); - int fsetpos(FILE *stream, const fpos_t *pos); - long int ftell(FILE *stream); - void rewind(FILE *stream); - void clearerr(FILE *stream); - int feof(FILE *stream); - int ferror(FILE *stream); - void perror(const char *s); - __STDC_WANT_LIB_EXT1__ - L_tmpnam_s TMP_MAX_S errno_t rsize_t - errno_t tmpfile_s(FILE * restrict * restrict streamptr); - errno_t tmpnam_s(char *s, rsize_t maxsize); - - - -[page 484] - - errno_t fopen_s(FILE * restrict * restrict streamptr, - const char * restrict filename, - const char * restrict mode); - errno_t freopen_s(FILE * restrict * restrict newstreamptr, - const char * restrict filename, - const char * restrict mode, - FILE * restrict stream); - int fprintf_s(FILE * restrict stream, - const char * restrict format, ...); - int fscanf_s(FILE * restrict stream, - const char * restrict format, ...); - int printf_s(const char * restrict format, ...); - int scanf_s(const char * restrict format, ...); - int snprintf_s(char * restrict s, rsize_t n, - const char * restrict format, ...); - int sprintf_s(char * restrict s, rsize_t n, - const char * restrict format, ...); - int sscanf_s(const char * restrict s, - const char * restrict format, ...); - int vfprintf_s(FILE * restrict stream, - const char * restrict format, - va_list arg); - int vfscanf_s(FILE * restrict stream, - const char * restrict format, - va_list arg); - int vprintf_s(const char * restrict format, - va_list arg); - int vscanf_s(const char * restrict format, - va_list arg); - int vsnprintf_s(char * restrict s, rsize_t n, - const char * restrict format, - va_list arg); - int vsprintf_s(char * restrict s, rsize_t n, - const char * restrict format, - va_list arg); - int vsscanf_s(const char * restrict s, - const char * restrict format, - va_list arg); - char *gets_s(char *s, rsize_t n); - - - -[page 485] - -B.21 General utilities - size_t ldiv_t EXIT_FAILURE MB_CUR_MAX - wchar_t lldiv_t EXIT_SUCCESS - div_t NULL RAND_MAX - double atof(const char *nptr); - int atoi(const char *nptr); - long int atol(const char *nptr); - long long int atoll(const char *nptr); - double strtod(const char * restrict nptr, - char ** restrict endptr); - float strtof(const char * restrict nptr, - char ** restrict endptr); - long double strtold(const char * restrict nptr, - char ** restrict endptr); - long int strtol(const char * restrict nptr, - char ** restrict endptr, int base); - long long int strtoll(const char * restrict nptr, - char ** restrict endptr, int base); - unsigned long int strtoul( - const char * restrict nptr, - char ** restrict endptr, int base); - unsigned long long int strtoull( - const char * restrict nptr, - char ** restrict endptr, int base); - int rand(void); - void srand(unsigned int seed); - void *aligned_alloc(size_t alignment, size_t size); - void *calloc(size_t nmemb, size_t size); - void free(void *ptr); - void *malloc(size_t size); - void *realloc(void *ptr, size_t size); - _Noreturn void abort(void); - int atexit(void (*func)(void)); - int at_quick_exit(void (*func)(void)); - _Noreturn void exit(int status); - _Noreturn void _Exit(int status); - char *getenv(const char *name); - _Noreturn void quick_exit(int status); - int system(const char *string); - - -[page 486] - - void *bsearch(const void *key, const void *base, - size_t nmemb, size_t size, - int (*compar)(const void *, const void *)); - void qsort(void *base, size_t nmemb, size_t size, - int (*compar)(const void *, const void *)); - int abs(int j); - long int labs(long int j); - long long int llabs(long long int j); - div_t div(int numer, int denom); - ldiv_t ldiv(long int numer, long int denom); - lldiv_t lldiv(long long int numer, - long long int denom); - int mblen(const char *s, size_t n); - int mbtowc(wchar_t * restrict pwc, - const char * restrict s, size_t n); - int wctomb(char *s, wchar_t wchar); - size_t mbstowcs(wchar_t * restrict pwcs, - const char * restrict s, size_t n); - size_t wcstombs(char * restrict s, - const wchar_t * restrict pwcs, size_t n); - __STDC_WANT_LIB_EXT1__ - errno_t - rsize_t - constraint_handler_t - constraint_handler_t set_constraint_handler_s( - constraint_handler_t handler); - void abort_handler_s( - const char * restrict msg, - void * restrict ptr, - errno_t error); - void ignore_handler_s( - const char * restrict msg, - void * restrict ptr, - errno_t error); - errno_t getenv_s(size_t * restrict len, - char * restrict value, rsize_t maxsize, - const char * restrict name); - - - - -[page 487] - - void *bsearch_s(const void *key, const void *base, - rsize_t nmemb, rsize_t size, - int (*compar)(const void *k, const void *y, - void *context), - void *context); - errno_t qsort_s(void *base, rsize_t nmemb, rsize_t size, - int (*compar)(const void *x, const void *y, - void *context), - void *context); - errno_t wctomb_s(int * restrict status, - char * restrict s, - rsize_t smax, - wchar_t wc); - errno_t mbstowcs_s(size_t * restrict retval, - wchar_t * restrict dst, rsize_t dstmax, - const char * restrict src, rsize_t len); - errno_t wcstombs_s(size_t * restrict retval, - char * restrict dst, rsize_t dstmax, - const wchar_t * restrict src, rsize_t len); -B.22 String handling - size_t - NULL - void *memcpy(void * restrict s1, - const void * restrict s2, size_t n); - void *memmove(void *s1, const void *s2, size_t n); - char *strcpy(char * restrict s1, - const char * restrict s2); - char *strncpy(char * restrict s1, - const char * restrict s2, size_t n); - char *strcat(char * restrict s1, - const char * restrict s2); - char *strncat(char * restrict s1, - const char * restrict s2, size_t n); - int memcmp(const void *s1, const void *s2, size_t n); - int strcmp(const char *s1, const char *s2); - int strcoll(const char *s1, const char *s2); - int strncmp(const char *s1, const char *s2, size_t n); - size_t strxfrm(char * restrict s1, - const char * restrict s2, size_t n); - void *memchr(const void *s, int c, size_t n); -[page 488] - - char *strchr(const char *s, int c); - size_t strcspn(const char *s1, const char *s2); - char *strpbrk(const char *s1, const char *s2); - char *strrchr(const char *s, int c); - size_t strspn(const char *s1, const char *s2); - char *strstr(const char *s1, const char *s2); - char *strtok(char * restrict s1, - const char * restrict s2); - void *memset(void *s, int c, size_t n); - char *strerror(int errnum); - size_t strlen(const char *s); - __STDC_WANT_LIB_EXT1__ - errno_t - rsize_t - errno_t memcpy_s(void * restrict s1, rsize_t s1max, - const void * restrict s2, rsize_t n); - errno_t memmove_s(void *s1, rsize_t s1max, - const void *s2, rsize_t n); - errno_t strcpy_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2); - errno_t strncpy_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2, - rsize_t n); - errno_t strcat_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2); - errno_t strncat_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2, - rsize_t n); - char *strtok_s(char * restrict s1, - rsize_t * restrict s1max, - const char * restrict s2, - char ** restrict ptr); - errno_t memset_s(void *s, rsize_t smax, int c, rsize_t n) - errno_t strerror_s(char *s, rsize_t maxsize, - errno_t errnum); - size_t strerrorlen_s(errno_t errnum); - -[page 489] - - size_t strnlen_s(const char *s, size_t maxsize); -B.23 Type-generic math - acos sqrt fmod nextafter - asin fabs frexp nexttoward - atan atan2 hypot remainder - acosh cbrt ilogb remquo - asinh ceil ldexp rint - atanh copysign lgamma round - cos erf llrint scalbn - sin erfc llround scalbln - tan exp2 log10 tgamma - cosh expm1 log1p trunc - sinh fdim log2 carg - tanh floor logb cimag - exp fma lrint conj - log fmax lround cproj - pow fmin nearbyint creal -B.24 Threads - ONCE_FLAG_INIT mtx_plain - TSS_DTOR_ITERATIONS mtx_recursive - cnd_t mtx_timed - thrd_t mtx_try - tss_t thrd_timeout - mtx_t thrd_success - tss_dtor_t thrd_busy - thrd_start_t thrd_error - once_flag thrd_nomem - xtime - void call_once(once_flag *flag, void (*func)(void)); - int cnd_broadcast(cnd_t *cond); - void cnd_destroy(cnd_t *cond); - int cnd_init(cnd_t *cond); - int cnd_signal(cnd_t *cond); - int cnd_timedwait(cnd_t *cond, mtx_t *mtx, - const xtime *xt); - int cnd_wait(cnd_t *cond, mtx_t *mtx); - void mtx_destroy(mtx_t *mtx); - int mtx_init(mtx_t *mtx, int type); - int mtx_lock(mtx_t *mtx); -[page 490] - - int mtx_timedlock(mtx_t *mtx, const xtime *xt); - int mtx_trylock(mtx_t *mtx); - int mtx_unlock(mtx_t *mtx); - int thrd_create(thrd_t *thr, thrd_start_t func, - void *arg); - thrd_t thrd_current(void); - int thrd_detach(thrd_t thr); - int thrd_equal(thrd_t thr0, thrd_t thr1); - void thrd_exit(int res); - int thrd_join(thrd_t thr, int *res); - void thrd_sleep(const xtime *xt); - void thrd_yield(void); - int tss_create(tss_t *key, tss_dtor_t dtor); - void tss_delete(tss_t key); - void *tss_get(tss_t key); - int tss_set(tss_t key, void *val); - int xtime_get(xtime *xt, int base); -B.25 Date and time - NULL size_t time_t - CLOCKS_PER_SEC clock_t struct tm - clock_t clock(void); - double difftime(time_t time1, time_t time0); - time_t mktime(struct tm *timeptr); - time_t time(time_t *timer); - char *asctime(const struct tm *timeptr); - char *ctime(const time_t *timer); - struct tm *gmtime(const time_t *timer); - struct tm *localtime(const time_t *timer); - size_t strftime(char * restrict s, - size_t maxsize, - const char * restrict format, - const struct tm * restrict timeptr); - __STDC_WANT_LIB_EXT1__ - errno_t - rsize_t - errno_t asctime_s(char *s, rsize_t maxsize, - const struct tm *timeptr); - - - -[page 491] - - errno_t ctime_s(char *s, rsize_t maxsize, - const time_t *timer); - struct tm *gmtime_s(const time_t * restrict timer, - struct tm * restrict result); - struct tm *localtime_s(const time_t * restrict timer, - struct tm * restrict result); -B.26 Unicode utilities - mbstate_t size_t char16_t char32_t - size_t mbrtoc16(char16_t * restrict pc16, - const char * restrict s, size_t n, - mbstate_t * restrict ps); - size_t c16rtomb(char * restrict s, char16_t c16, - mbstate_t * restrict ps); - size_t mbrtoc32(char32_t * restrict pc32, - const char * restrict s, size_t n, - mbstate_t * restrict ps); - size_t c32rtomb(char * restrict s, char32_t c32, - mbstate_t * restrict ps); -B.27 Extended multibyte/wide character utilities - wchar_t wint_t WCHAR_MAX - size_t struct tm WCHAR_MIN - mbstate_t NULL WEOF - int fwprintf(FILE * restrict stream, - const wchar_t * restrict format, ...); - int fwscanf(FILE * restrict stream, - const wchar_t * restrict format, ...); - int swprintf(wchar_t * restrict s, size_t n, - const wchar_t * restrict format, ...); - int swscanf(const wchar_t * restrict s, - const wchar_t * restrict format, ...); - int vfwprintf(FILE * restrict stream, - const wchar_t * restrict format, va_list arg); - int vfwscanf(FILE * restrict stream, - const wchar_t * restrict format, va_list arg); - int vswprintf(wchar_t * restrict s, size_t n, - const wchar_t * restrict format, va_list arg); - - - -[page 492] - - int vswscanf(const wchar_t * restrict s, - const wchar_t * restrict format, va_list arg); - int vwprintf(const wchar_t * restrict format, - va_list arg); - int vwscanf(const wchar_t * restrict format, - va_list arg); - int wprintf(const wchar_t * restrict format, ...); - int wscanf(const wchar_t * restrict format, ...); - wint_t fgetwc(FILE *stream); - wchar_t *fgetws(wchar_t * restrict s, int n, - FILE * restrict stream); - wint_t fputwc(wchar_t c, FILE *stream); - int fputws(const wchar_t * restrict s, - FILE * restrict stream); - int fwide(FILE *stream, int mode); - wint_t getwc(FILE *stream); - wint_t getwchar(void); - wint_t putwc(wchar_t c, FILE *stream); - wint_t putwchar(wchar_t c); - wint_t ungetwc(wint_t c, FILE *stream); - double wcstod(const wchar_t * restrict nptr, - wchar_t ** restrict endptr); - float wcstof(const wchar_t * restrict nptr, - wchar_t ** restrict endptr); - long double wcstold(const wchar_t * restrict nptr, - wchar_t ** restrict endptr); - long int wcstol(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - long long int wcstoll(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - unsigned long int wcstoul(const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - unsigned long long int wcstoull( - const wchar_t * restrict nptr, - wchar_t ** restrict endptr, int base); - wchar_t *wcscpy(wchar_t * restrict s1, - const wchar_t * restrict s2); - wchar_t *wcsncpy(wchar_t * restrict s1, - const wchar_t * restrict s2, size_t n); - - - -[page 493] - - wchar_t *wmemcpy(wchar_t * restrict s1, - const wchar_t * restrict s2, size_t n); - wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2, - size_t n); - wchar_t *wcscat(wchar_t * restrict s1, - const wchar_t * restrict s2); - wchar_t *wcsncat(wchar_t * restrict s1, - const wchar_t * restrict s2, size_t n); - int wcscmp(const wchar_t *s1, const wchar_t *s2); - int wcscoll(const wchar_t *s1, const wchar_t *s2); - int wcsncmp(const wchar_t *s1, const wchar_t *s2, - size_t n); - size_t wcsxfrm(wchar_t * restrict s1, - const wchar_t * restrict s2, size_t n); - int wmemcmp(const wchar_t *s1, const wchar_t *s2, - size_t n); - wchar_t *wcschr(const wchar_t *s, wchar_t c); - size_t wcscspn(const wchar_t *s1, const wchar_t *s2); - wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2); - wchar_t *wcsrchr(const wchar_t *s, wchar_t c); - size_t wcsspn(const wchar_t *s1, const wchar_t *s2); - wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2); - wchar_t *wcstok(wchar_t * restrict s1, - const wchar_t * restrict s2, - wchar_t ** restrict ptr); - wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n); - size_t wcslen(const wchar_t *s); - wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n); - size_t wcsftime(wchar_t * restrict s, size_t maxsize, - const wchar_t * restrict format, - const struct tm * restrict timeptr); - wint_t btowc(int c); - int wctob(wint_t c); - int mbsinit(const mbstate_t *ps); - size_t mbrlen(const char * restrict s, size_t n, - mbstate_t * restrict ps); - size_t mbrtowc(wchar_t * restrict pwc, - const char * restrict s, size_t n, - mbstate_t * restrict ps); - - - -[page 494] - - size_t wcrtomb(char * restrict s, wchar_t wc, - mbstate_t * restrict ps); - size_t mbsrtowcs(wchar_t * restrict dst, - const char ** restrict src, size_t len, - mbstate_t * restrict ps); - size_t wcsrtombs(char * restrict dst, - const wchar_t ** restrict src, size_t len, - mbstate_t * restrict ps); - __STDC_WANT_LIB_EXT1__ - errno_t - rsize_t - int fwprintf_s(FILE * restrict stream, - const wchar_t * restrict format, ...); - int fwscanf_s(FILE * restrict stream, - const wchar_t * restrict format, ...); - int snwprintf_s(wchar_t * restrict s, - rsize_t n, - const wchar_t * restrict format, ...); - int swprintf_s(wchar_t * restrict s, rsize_t n, - const wchar_t * restrict format, ...); - int swscanf_s(const wchar_t * restrict s, - const wchar_t * restrict format, ...); - int vfwprintf_s(FILE * restrict stream, - const wchar_t * restrict format, - va_list arg); - int vfwscanf_s(FILE * restrict stream, - const wchar_t * restrict format, va_list arg); - int vsnwprintf_s(wchar_t * restrict s, - rsize_t n, - const wchar_t * restrict format, - va_list arg); - int vswprintf_s(wchar_t * restrict s, - rsize_t n, - const wchar_t * restrict format, - va_list arg); - int vswscanf_s(const wchar_t * restrict s, - const wchar_t * restrict format, - va_list arg); - - - -[page 495] - - int vwprintf_s(const wchar_t * restrict format, - va_list arg); - int vwscanf_s(const wchar_t * restrict format, - va_list arg); - int wprintf_s(const wchar_t * restrict format, ...); - int wscanf_s(const wchar_t * restrict format, ...); - errno_t wcscpy_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2); - errno_t wcsncpy_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2, - rsize_t n); - errno_t wmemcpy_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2, - rsize_t n); - errno_t wmemmove_s(wchar_t *s1, rsize_t s1max, - const wchar_t *s2, rsize_t n); - errno_t wcscat_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2); - errno_t wcsncat_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2, - rsize_t n); - wchar_t *wcstok_s(wchar_t * restrict s1, - rsize_t * restrict s1max, - const wchar_t * restrict s2, - wchar_t ** restrict ptr); - size_t wcsnlen_s(const wchar_t *s, size_t maxsize); - errno_t wcrtomb_s(size_t * restrict retval, - char * restrict s, rsize_t smax, - wchar_t wc, mbstate_t * restrict ps); - errno_t mbsrtowcs_s(size_t * restrict retval, - wchar_t * restrict dst, rsize_t dstmax, - const char ** restrict src, rsize_t len, - mbstate_t * restrict ps); - - - - -[page 496] - - errno_t wcsrtombs_s(size_t * restrict retval, - char * restrict dst, rsize_t dstmax, - const wchar_t ** restrict src, rsize_t len, - mbstate_t * restrict ps); -B.28 Wide character classification and mapping utilities - wint_t wctrans_t wctype_t WEOF - int iswalnum(wint_t wc); - int iswalpha(wint_t wc); - int iswblank(wint_t wc); - int iswcntrl(wint_t wc); - int iswdigit(wint_t wc); - int iswgraph(wint_t wc); - int iswlower(wint_t wc); - int iswprint(wint_t wc); - int iswpunct(wint_t wc); - int iswspace(wint_t wc); - int iswupper(wint_t wc); - int iswxdigit(wint_t wc); - int iswctype(wint_t wc, wctype_t desc); - wctype_t wctype(const char *property); - wint_t towlower(wint_t wc); - wint_t towupper(wint_t wc); - wint_t towctrans(wint_t wc, wctrans_t desc); - wctrans_t wctrans(const char *property); - - - - -[page 497] - - Annex C - (informative) - Sequence points -1 The following are the sequence points described in 5.1.2.3: - -- Between the evaluations of the function designator and actual arguments in a function - call and the actual call. (6.5.2.2). - -- Between the evaluations of the first and second operands of the following operators: - logical AND && (6.5.13); logical OR || (6.5.14); comma , (6.5.17). - -- Between the evaluations of the first operand of the conditional ? : operator and - whichever of the second and third operands is evaluated (6.5.15). - -- The end of a full declarator: declarators (6.7.6); - -- Between the evaluation of a full expression and the next full expression to be - evaluated. The following are full expressions: an initializer that is not part of a - compound literal (6.7.9); the expression in an expression statement (6.8.3); the - controlling expression of a selection statement (if or switch) (6.8.4); the - controlling expression of a while or do statement (6.8.5); each of the (optional) - expressions of a for statement (6.8.5.3); the (optional) expression in a return - statement (6.8.6.4). - -- Immediately before a library function returns (7.1.4). - -- After the actions associated with each formatted input/output function conversion - specifier (7.21.6, 7.28.2). - -- Immediately before and immediately after each call to a comparison function, and - also between any call to a comparison function and any movement of the objects - passed as arguments to that call (7.22.5). - - - - -[page 498] - - Annex D - (normative) - Universal character names for identifiers -1 This clause lists the hexadecimal code values that are valid in universal character names - in identifiers. -2 This table is reproduced unchanged from ISO/IEC TR 10176:1998, produced by ISO/IEC - JTC 1/SC 22/WG 20, except for the omission of ranges that are part of the basic character - sets. - Latin: 00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217, - 0250-02A8, 1E00-1E9B, 1EA0-1EF9, 207F - Greek: 0386, 0388-038A, 038C, 038E-03A1, 03A3-03CE, 03D0-03D6, - 03DA, 03DC, 03DE, 03E0, 03E2-03F3, 1F00-1F15, 1F18-1F1D, - 1F20-1F45, 1F48-1F4D, 1F50-1F57, 1F59, 1F5B, 1F5D, - 1F5F-1F7D, 1F80-1FB4, 1FB6-1FBC, 1FC2-1FC4, 1FC6-1FCC, - 1FD0-1FD3, 1FD6-1FDB, 1FE0-1FEC, 1FF2-1FF4, 1FF6-1FFC - Cyrillic: 0401-040C, 040E-044F, 0451-045C, 045E-0481, 0490-04C4, - 04C7-04C8, 04CB-04CC, 04D0-04EB, 04EE-04F5, 04F8-04F9 - Armenian: 0531-0556, 0561-0587 - Hebrew: 05B0-05B9, 05BB-05BD, 05BF, 05C1-05C2, 05D0-05EA, - 05F0-05F2 - Arabic: 0621-063A, 0640-0652, 0670-06B7, 06BA-06BE, 06C0-06CE, - 06D0-06DC, 06E5-06E8, 06EA-06ED - Devanagari: 0901-0903, 0905-0939, 093E-094D, 0950-0952, 0958-0963 - Bengali: 0981-0983, 0985-098C, 098F-0990, 0993-09A8, 09AA-09B0, - 09B2, 09B6-09B9, 09BE-09C4, 09C7-09C8, 09CB-09CD, - 09DC-09DD, 09DF-09E3, 09F0-09F1 - Gurmukhi: 0A02, 0A05-0A0A, 0A0F-0A10, 0A13-0A28, 0A2A-0A30, - 0A32-0A33, 0A35-0A36, 0A38-0A39, 0A3E-0A42, 0A47-0A48, - 0A4B-0A4D, 0A59-0A5C, 0A5E, 0A74 - Gujarati: 0A81-0A83, 0A85-0A8B, 0A8D, 0A8F-0A91, 0A93-0AA8, - 0AAA-0AB0, 0AB2-0AB3, 0AB5-0AB9, 0ABD-0AC5, - 0AC7-0AC9, 0ACB-0ACD, 0AD0, 0AE0 - Oriya: 0B01-0B03, 0B05-0B0C, 0B0F-0B10, 0B13-0B28, 0B2A-0B30, - 0B32-0B33, 0B36-0B39, 0B3E-0B43, 0B47-0B48, 0B4B-0B4D, -[page 499] - - 0B5C-0B5D, 0B5F-0B61 -Tamil: 0B82-0B83, 0B85-0B8A, 0B8E-0B90, 0B92-0B95, 0B99-0B9A, - 0B9C, 0B9E-0B9F, 0BA3-0BA4, 0BA8-0BAA, 0BAE-0BB5, - 0BB7-0BB9, 0BBE-0BC2, 0BC6-0BC8, 0BCA-0BCD -Telugu: 0C01-0C03, 0C05-0C0C, 0C0E-0C10, 0C12-0C28, 0C2A-0C33, - 0C35-0C39, 0C3E-0C44, 0C46-0C48, 0C4A-0C4D, 0C60-0C61 -Kannada: 0C82-0C83, 0C85-0C8C, 0C8E-0C90, 0C92-0CA8, 0CAA-0CB3, - 0CB5-0CB9, 0CBE-0CC4, 0CC6-0CC8, 0CCA-0CCD, 0CDE, - 0CE0-0CE1 -Malayalam: 0D02-0D03, 0D05-0D0C, 0D0E-0D10, 0D12-0D28, 0D2A-0D39, - 0D3E-0D43, 0D46-0D48, 0D4A-0D4D, 0D60-0D61 -Thai: 0E01-0E3A, 0E40-0E5B -Lao: 0E81-0E82, 0E84, 0E87-0E88, 0E8A, 0E8D, 0E94-0E97, - 0E99-0E9F, 0EA1-0EA3, 0EA5, 0EA7, 0EAA-0EAB, - 0EAD-0EAE, 0EB0-0EB9, 0EBB-0EBD, 0EC0-0EC4, 0EC6, - 0EC8-0ECD, 0EDC-0EDD -Tibetan: 0F00, 0F18-0F19, 0F35, 0F37, 0F39, 0F3E-0F47, 0F49-0F69, - 0F71-0F84, 0F86-0F8B, 0F90-0F95, 0F97, 0F99-0FAD, - 0FB1-0FB7, 0FB9 -Georgian: 10A0-10C5, 10D0-10F6 -Hiragana: 3041-3093, 309B-309C -Katakana: 30A1-30F6, 30FB-30FC -Bopomofo: 3105-312C -CJK Unified Ideographs: 4E00-9FA5 -Hangul: AC00-D7A3 -Digits: 0660-0669, 06F0-06F9, 0966-096F, 09E6-09EF, 0A66-0A6F, - 0AE6-0AEF, 0B66-0B6F, 0BE7-0BEF, 0C66-0C6F, 0CE6-0CEF, - 0D66-0D6F, 0E50-0E59, 0ED0-0ED9, 0F20-0F33 -Special characters: 00B5, 00B7, 02B0-02B8, 02BB, 02BD-02C1, 02D0-02D1, - 02E0-02E4, 037A, 0559, 093D, 0B3D, 1FBE, 203F-2040, 2102, - 2107, 210A-2113, 2115, 2118-211D, 2124, 2126, 2128, 212A-2131, - 2133-2138, 2160-2182, 3005-3007, 3021-3029 - - - - -[page 500] - - Annex E - (informative) - Implementation limits -1 The contents of the header are given below, in alphabetical order. The - minimum magnitudes shown shall be replaced by implementation-defined magnitudes - with the same sign. The values shall all be constant expressions suitable for use in #if - preprocessing directives. The components are described further in 5.2.4.2.1. - #define CHAR_BIT 8 - #define CHAR_MAX UCHAR_MAX or SCHAR_MAX - #define CHAR_MIN 0 or SCHAR_MIN - #define INT_MAX +32767 - #define INT_MIN -32767 - #define LONG_MAX +2147483647 - #define LONG_MIN -2147483647 - #define LLONG_MAX +9223372036854775807 - #define LLONG_MIN -9223372036854775807 - #define MB_LEN_MAX 1 - #define SCHAR_MAX +127 - #define SCHAR_MIN -127 - #define SHRT_MAX +32767 - #define SHRT_MIN -32767 - #define UCHAR_MAX 255 - #define USHRT_MAX 65535 - #define UINT_MAX 65535 - #define ULONG_MAX 4294967295 - #define ULLONG_MAX 18446744073709551615 -2 The contents of the header are given below. All integer values, except - FLT_ROUNDS, shall be constant expressions suitable for use in #if preprocessing - directives; all floating values shall be constant expressions. The components are - described further in 5.2.4.2.2. -3 The values given in the following list shall be replaced by implementation-defined - expressions: - #define FLT_EVAL_METHOD - #define FLT_ROUNDS -4 The values given in the following list shall be replaced by implementation-defined - constant expressions that are greater or equal in magnitude (absolute value) to those - shown, with the same sign: -[page 501] - - #define DLB_DECIMAL_DIG 10 - #define DBL_DIG 10 - #define DBL_MANT_DIG - #define DBL_MAX_10_EXP +37 - #define DBL_MAX_EXP - #define DBL_MIN_10_EXP -37 - #define DBL_MIN_EXP - #define DECIMAL_DIG 10 - #define FLT_DECIMAL_DIG 6 - #define FLT_DIG 6 - #define FLT_MANT_DIG - #define FLT_MAX_10_EXP +37 - #define FLT_MAX_EXP - #define FLT_MIN_10_EXP -37 - #define FLT_MIN_EXP - #define FLT_RADIX 2 - #define LDLB_DECIMAL_DIG 10 - #define LDBL_DIG 10 - #define LDBL_MANT_DIG - #define LDBL_MAX_10_EXP +37 - #define LDBL_MAX_EXP - #define LDBL_MIN_10_EXP -37 - #define LDBL_MIN_EXP -5 The values given in the following list shall be replaced by implementation-defined - constant expressions with values that are greater than or equal to those shown: - #define DBL_MAX 1E+37 - #define FLT_MAX 1E+37 - #define LDBL_MAX 1E+37 -6 The values given in the following list shall be replaced by implementation-defined - constant expressions with (positive) values that are less than or equal to those shown: - #define DBL_EPSILON 1E-9 - #define DBL_MIN 1E-37 - #define FLT_EPSILON 1E-5 - #define FLT_MIN 1E-37 - #define LDBL_EPSILON 1E-9 - #define LDBL_MIN 1E-37 - - - - -[page 502] - - Annex F - (normative) - IEC 60559 floating-point arithmetic - F.1 Introduction -1 This annex specifies C language support for the IEC 60559 floating-point standard. The - IEC 60559 floating-point standard is specifically Binary floating-point arithmetic for - microprocessor systems, second edition (IEC 60559:1989), previously designated - IEC 559:1989 and as IEEE Standard for Binary Floating-Point Arithmetic - (ANSI/IEEE 754-1985). IEEE Standard for Radix-Independent Floating-Point - Arithmetic (ANSI/IEEE 854-1987) generalizes the binary standard to remove - dependencies on radix and word length. IEC 60559 generally refers to the floating-point - standard, as in IEC 60559 operation, IEC 60559 format, etc. An implementation that - defines __STDC_IEC_559__ shall conform to the specifications in this annex.339) - Where a binding between the C language and IEC 60559 is indicated, the - IEC 60559-specified behavior is adopted by reference, unless stated otherwise. Since - negative and positive infinity are representable in IEC 60559 formats, all real numbers lie - within the range of representable values. - F.2 Types -1 The C floating types match the IEC 60559 formats as follows: - -- The float type matches the IEC 60559 single format. - -- The double type matches the IEC 60559 double format. - -- The long double type matches an IEC 60559 extended format,340) else a - non-IEC 60559 extended format, else the IEC 60559 double format. - Any non-IEC 60559 extended format used for the long double type shall have more - precision than IEC 60559 double and at least the range of IEC 60559 double.341) - - - - - 339) Implementations that do not define __STDC_IEC_559__ are not required to conform to these - specifications. - 340) ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit - and quadruple 128-bit IEC 60559 formats. - 341) A non-IEC 60559 long double type is required to provide infinity and NaNs, as its values include - all double values. - -[page 503] - - Recommended practice -2 The long double type should match an IEC 60559 extended format. - F.2.1 Infinities, signed zeros, and NaNs -1 This specification does not define the behavior of signaling NaNs.342) It generally uses - the term NaN to denote quiet NaNs. The NAN and INFINITY macros and the nan - functions in provide designations for IEC 60559 NaNs and infinities. - F.3 Operators and functions -1 C operators and functions provide IEC 60559 required and recommended facilities as - listed below. - -- The +, -, *, and / operators provide the IEC 60559 add, subtract, multiply, and - divide operations. - -- The sqrt functions in provide the IEC 60559 square root operation. - -- The remainder functions in provide the IEC 60559 remainder - operation. The remquo functions in provide the same operation but - with additional information. - -- The rint functions in provide the IEC 60559 operation that rounds a - floating-point number to an integer value (in the same precision). The nearbyint - functions in provide the nearbyinteger function recommended in the - Appendix to ANSI/IEEE 854. - -- The conversions for floating types provide the IEC 60559 conversions between - floating-point precisions. - -- The conversions from integer to floating types provide the IEC 60559 conversions - from integer to floating point. - -- The conversions from floating to integer types provide IEC 60559-like conversions - but always round toward zero. - -- The lrint and llrint functions in provide the IEC 60559 - conversions, which honor the directed rounding mode, from floating point to the - long int and long long int integer formats. The lrint and llrint - functions can be used to implement IEC 60559 conversions from floating to other - integer formats. - -- The translation time conversion of floating constants and the strtod, strtof, - strtold, fprintf, fscanf, and related library functions in , - - - 342) Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are - sufficient for closure of the arithmetic. - -[page 504] - - , and provide IEC 60559 binary-decimal conversions. The - strtold function in provides the conv function recommended in the - Appendix to ANSI/IEEE 854. --- The relational and equality operators provide IEC 60559 comparisons. IEC 60559 - identifies a need for additional comparison predicates to facilitate writing code that - accounts for NaNs. The comparison macros (isgreater, isgreaterequal, - isless, islessequal, islessgreater, and isunordered) in - supplement the language operators to address this need. The islessgreater and - isunordered macros provide respectively a quiet version of the <> predicate and - the unordered predicate recommended in the Appendix to IEC 60559. --- The feclearexcept, feraiseexcept, and fetestexcept functions in - provide the facility to test and alter the IEC 60559 floating-point - exception status flags. The fegetexceptflag and fesetexceptflag - functions in provide the facility to save and restore all five status flags at - one time. These functions are used in conjunction with the type fexcept_t and the - floating-point exception macros (FE_INEXACT, FE_DIVBYZERO, - FE_UNDERFLOW, FE_OVERFLOW, FE_INVALID) also in . --- The fegetround and fesetround functions in provide the facility - to select among the IEC 60559 directed rounding modes represented by the rounding - direction macros in (FE_TONEAREST, FE_UPWARD, FE_DOWNWARD, - FE_TOWARDZERO) and the values 0, 1, 2, and 3 of FLT_ROUNDS are the - IEC 60559 directed rounding modes. --- The fegetenv, feholdexcept, fesetenv, and feupdateenv functions in - provide a facility to manage the floating-point environment, comprising - the IEC 60559 status flags and control modes. --- The copysign functions in provide the copysign function - recommended in the Appendix to IEC 60559. --- The fabs functions in provide the abs function recommended in the - Appendix to IEC 60559. --- The unary minus (-) operator provides the unary minus (-) operation recommended - in the Appendix to IEC 60559. --- The scalbn and scalbln functions in provide the scalb function - recommended in the Appendix to IEC 60559. --- The logb functions in provide the logb function recommended in the - Appendix to IEC 60559, but following the newer specifications in ANSI/IEEE 854. --- The nextafter and nexttoward functions in provide the nextafter - function recommended in the Appendix to IEC 60559 (but with a minor change to - -[page 505] - - better handle signed zeros). - -- The isfinite macro in provides the finite function recommended in - the Appendix to IEC 60559. - -- The isnan macro in provides the isnan function recommended in the - Appendix to IEC 60559. - -- The signbit macro and the fpclassify macro in , used in - conjunction with the number classification macros (FP_NAN, FP_INFINITE, - FP_NORMAL, FP_SUBNORMAL, FP_ZERO), provide the facility of the class - function recommended in the Appendix to IEC 60559 (except that the classification - macros defined in 7.12.3 do not distinguish signaling from quiet NaNs). - F.4 Floating to integer conversion -1 If the integer type is _Bool, 6.3.1.2 applies and no floating-point exceptions are raised - (even for NaN). Otherwise, if the floating value is infinite or NaN or if the integral part - of the floating value exceeds the range of the integer type, then the ''invalid'' floating- - point exception is raised and the resulting value is unspecified. Otherwise, the resulting - value is determined by 6.3.1.4. Conversion of an integral floating value that does not - exceed the range of the integer type raises no floating-point exceptions; whether - conversion of a non-integral floating value raises the ''inexact'' floating-point exception is - unspecified.343) - F.5 Binary-decimal conversion -1 Conversion from the widest supported IEC 60559 format to decimal with - DECIMAL_DIG digits and back is the identity function.344) -2 Conversions involving IEC 60559 formats follow all pertinent recommended practice. In - particular, conversion between any supported IEC 60559 format and decimal with - DECIMAL_DIG or fewer significant digits is correctly rounded (honoring the current - rounding mode), which assures that conversion from the widest supported IEC 60559 - format to decimal with DECIMAL_DIG digits and back is the identity function. - - - - 343) ANSI/IEEE 854, but not IEC 60559 (ANSI/IEEE 754), directly specifies that floating-to-integer - conversions raise the ''inexact'' floating-point exception for non-integer in-range values. In those - cases where it matters, library functions can be used to effect such conversions with or without raising - the ''inexact'' floating-point exception. See rint, lrint, llrint, and nearbyint in - . - 344) If the minimum-width IEC 60559 extended format (64 bits of precision) is supported, - DECIMAL_DIG shall be at least 21. If IEC 60559 double (53 bits of precision) is the widest - IEC 60559 format supported, then DECIMAL_DIG shall be at least 17. (By contrast, LDBL_DIG and - DBL_DIG are 18 and 15, respectively, for these formats.) - -[page 506] - -3 Functions such as strtod that convert character sequences to floating types honor the - rounding direction. Hence, if the rounding direction might be upward or downward, the - implementation cannot convert a minus-signed sequence by negating the converted - unsigned sequence. - F.6 The return statement - If the return expression is evaluated in a floating-point format different from the return - type, the expression is converted to the return type of the function and the resulting value - is returned to the caller. - F.7 Contracted expressions -1 A contracted expression is correctly rounded (once) and treats infinities, NaNs, signed - zeros, subnormals, and the rounding directions in a manner consistent with the basic - arithmetic operations covered by IEC 60559. - Recommended practice -2 A contracted expression should raise floating-point exceptions in a manner generally - consistent with the basic arithmetic operations. - F.8 Floating-point environment -1 The floating-point environment defined in includes the IEC 60559 floating- - point exception status flags and directed-rounding control modes. It includes also - IEC 60559 dynamic rounding precision and trap enablement modes, if the - implementation supports them.345) - F.8.1 Environment management -1 IEC 60559 requires that floating-point operations implicitly raise floating-point exception - status flags, and that rounding control modes can be set explicitly to affect result values of - floating-point operations. When the state for the FENV_ACCESS pragma (defined in - ) is ''on'', these changes to the floating-point state are treated as side effects - which respect sequence points.346) - - - - - 345) This specification does not require dynamic rounding precision nor trap enablement modes. - 346) If the state for the FENV_ACCESS pragma is ''off'', the implementation is free to assume the floating- - point control modes will be the default ones and the floating-point status flags will not be tested, - which allows certain optimizations (see F.9). - -[page 507] - - F.8.2 Translation -1 During translation the IEC 60559 default modes are in effect: - -- The rounding direction mode is rounding to nearest. - -- The rounding precision mode (if supported) is set so that results are not shortened. - -- Trapping or stopping (if supported) is disabled on all floating-point exceptions. - Recommended practice -2 The implementation should produce a diagnostic message for each translation-time - floating-point exception, other than ''inexact'';347) the implementation should then - proceed with the translation of the program. - F.8.3 Execution -1 At program startup the floating-point environment is initialized as prescribed by - IEC 60559: - -- All floating-point exception status flags are cleared. - -- The rounding direction mode is rounding to nearest. - -- The dynamic rounding precision mode (if supported) is set so that results are not - shortened. - -- Trapping or stopping (if supported) is disabled on all floating-point exceptions. - F.8.4 Constant expressions -1 An arithmetic constant expression of floating type, other than one in an initializer for an - object that has static or thread storage duration, is evaluated (as if) during execution; thus, - it is affected by any operative floating-point control modes and raises floating-point - exceptions as required by IEC 60559 (provided the state for the FENV_ACCESS pragma - is ''on'').348) -2 EXAMPLE - - - - 347) As floating constants are converted to appropriate internal representations at translation time, their - conversion is subject to default rounding modes and raises no execution-time floating-point exceptions - (even where the state of the FENV_ACCESS pragma is ''on''). Library functions, for example - strtod, provide execution-time conversion of numeric strings. - 348) Where the state for the FENV_ACCESS pragma is ''on'', results of inexact expressions like 1.0/3.0 - are affected by rounding modes set at execution time, and expressions such as 0.0/0.0 and - 1.0/0.0 generate execution-time floating-point exceptions. The programmer can achieve the - efficiency of translation-time evaluation through static initialization, such as - const static double one_third = 1.0/3.0; - - -[page 508] - - #include - #pragma STDC FENV_ACCESS ON - void f(void) - { - float w[] = { 0.0/0.0 }; // raises an exception - static float x = 0.0/0.0; // does not raise an exception - float y = 0.0/0.0; // raises an exception - double z = 0.0/0.0; // raises an exception - /* ... */ - } -3 For the static initialization, the division is done at translation time, raising no (execution-time) floating- - point exceptions. On the other hand, for the three automatic initializations the invalid division occurs at - execution time. - - F.8.5 Initialization -1 All computation for automatic initialization is done (as if) at execution time; thus, it is - affected by any operative modes and raises floating-point exceptions as required by - IEC 60559 (provided the state for the FENV_ACCESS pragma is ''on''). All computation - for initialization of objects that have static or thread storage duration is done (as if) at - translation time. -2 EXAMPLE - #include - #pragma STDC FENV_ACCESS ON - void f(void) - { - float u[] = { 1.1e75 }; // raises exceptions - static float v = 1.1e75; // does not raise exceptions - float w = 1.1e75; // raises exceptions - double x = 1.1e75; // may raise exceptions - float y = 1.1e75f; // may raise exceptions - long double z = 1.1e75; // does not raise exceptions - /* ... */ - } -3 The static initialization of v raises no (execution-time) floating-point exceptions because its computation is - done at translation time. The automatic initialization of u and w require an execution-time conversion to - float of the wider value 1.1e75, which raises floating-point exceptions. The automatic initializations - of x and y entail execution-time conversion; however, in some expression evaluation methods, the - conversions is not to a narrower format, in which case no floating-point exception is raised.349) The - automatic initialization of z entails execution-time conversion, but not to a narrower format, so no floating- - point exception is raised. Note that the conversions of the floating constants 1.1e75 and 1.1e75f to - - - - 349) Use of float_t and double_t variables increases the likelihood of translation-time computation. - For example, the automatic initialization - double_t x = 1.1e75; - could be done at translation time, regardless of the expression evaluation method. - -[page 509] - - their internal representations occur at translation time in all cases. - - F.8.6 Changing the environment -1 Operations defined in 6.5 and functions and macros defined for the standard libraries - change floating-point status flags and control modes just as indicated by their - specifications (including conformance to IEC 60559). They do not change flags or modes - (so as to be detectable by the user) in any other cases. -2 If the argument to the feraiseexcept function in represents IEC 60559 - valid coincident floating-point exceptions for atomic operations (namely ''overflow'' and - ''inexact'', or ''underflow'' and ''inexact''), then ''overflow'' or ''underflow'' is raised - before ''inexact''. - F.9 Optimization -1 This section identifies code transformations that might subvert IEC 60559-specified - behavior, and others that do not. - F.9.1 Global transformations -1 Floating-point arithmetic operations and external function calls may entail side effects - which optimization shall honor, at least where the state of the FENV_ACCESS pragma is - ''on''. The flags and modes in the floating-point environment may be regarded as global - variables; floating-point operations (+, *, etc.) implicitly read the modes and write the - flags. -2 Concern about side effects may inhibit code motion and removal of seemingly useless - code. For example, in - #include - #pragma STDC FENV_ACCESS ON - void f(double x) - { - /* ... */ - for (i = 0; i < n; i++) x + 1; - /* ... */ - } - x + 1 might raise floating-point exceptions, so cannot be removed. And since the loop - body might not execute (maybe 0 >= n), x + 1 cannot be moved out of the loop. (Of - course these optimizations are valid if the implementation can rule out the nettlesome - cases.) -3 This specification does not require support for trap handlers that maintain information - about the order or count of floating-point exceptions. Therefore, between function calls, - floating-point exceptions need not be precise: the actual order and number of occurrences - of floating-point exceptions (> 1) may vary from what the source code expresses. Thus, -[page 510] - - the preceding loop could be treated as - if (0 < n) x + 1; - F.9.2 Expression transformations -1 x/2 (<->) x x 0.5 Although similar transformations involving inexact constants - generally do not yield numerically equivalent expressions, if the - constants are exact then such transformations can be made on - IEC 60559 machines and others that round perfectly. - 1 x x and x/1 (->) x The expressions 1 x x, x/1, and x are equivalent (on IEC 60559 - machines, among others).350) - x/x (->) 1.0 The expressions x/x and 1.0 are not equivalent if x can be zero, - infinite, or NaN. - x - y (<->) x + (-y) The expressions x - y, x + (-y), and (-y) + x are equivalent (on - IEC 60559 machines, among others). - x - y (<->) -(y - x) The expressions x - y and -(y - x) are not equivalent because 1 - 1 - is +0 but -(1 - 1) is -0 (in the default rounding direction).351) - x - x (->) 0.0 The expressions x - x and 0.0 are not equivalent if x is a NaN or - infinite. - 0 x x (->) 0.0 The expressions 0 x x and 0.0 are not equivalent if x is a NaN, - infinite, or -0. - x+0(->) x The expressions x + 0 and x are not equivalent if x is -0, because - (-0) + (+0) yields +0 (in the default rounding direction), not -0. - x-0(->) x (+0) - (+0) yields -0 when rounding is downward (toward -(inf)), but - +0 otherwise, and (-0) - (+0) always yields -0; so, if the state of the - FENV_ACCESS pragma is ''off'', promising default rounding, then - the implementation can replace x - 0 by x, even if x might be zero. - -x (<->) 0 - x The expressions -x and 0 - x are not equivalent if x is +0, because - -(+0) yields -0, but 0 - (+0) yields +0 (unless rounding is - downward). - - 350) Strict support for signaling NaNs -- not required by this specification -- would invalidate these and - other transformations that remove arithmetic operators. - 351) IEC 60559 prescribes a signed zero to preserve mathematical identities across certain discontinuities. - Examples include: - 1/(1/ (+-) (inf)) is (+-) (inf) - and - conj(csqrt(z)) is csqrt(conj(z)), - for complex z. - -[page 511] - - F.9.3 Relational operators -1 x != x (->) false The expression x != x is true if x is a NaN. - x = x (->) true The expression x = x is false if x is a NaN. - x < y (->) isless(x,y) (and similarly for <=, >, >=) Though numerically equal, these - expressions are not equivalent because of side effects when x or y is a - NaN and the state of the FENV_ACCESS pragma is ''on''. This - transformation, which would be desirable if extra code were required - to cause the ''invalid'' floating-point exception for unordered cases, - could be performed provided the state of the FENV_ACCESS pragma - is ''off''. - The sense of relational operators shall be maintained. This includes handling unordered - cases as expressed by the source code. -2 EXAMPLE - // calls g and raises ''invalid'' if a and b are unordered - if (a < b) - f(); - else - g(); - is not equivalent to - // calls f and raises ''invalid'' if a and b are unordered - if (a >= b) - g(); - else - f(); - nor to - // calls f without raising ''invalid'' if a and b are unordered - if (isgreaterequal(a,b)) - g(); - else - f(); - nor, unless the state of the FENV_ACCESS pragma is ''off'', to - // calls g without raising ''invalid'' if a and b are unordered - if (isless(a,b)) - f(); - else - g(); - but is equivalent to - - - - -[page 512] - - if (!(a < b)) - g(); - else - f(); - - F.9.4 Constant arithmetic -1 The implementation shall honor floating-point exceptions raised by execution-time - constant arithmetic wherever the state of the FENV_ACCESS pragma is ''on''. (See F.8.4 - and F.8.5.) An operation on constants that raises no floating-point exception can be - folded during translation, except, if the state of the FENV_ACCESS pragma is ''on'', a - further check is required to assure that changing the rounding direction to downward does - not alter the sign of the result,352) and implementations that support dynamic rounding - precision modes shall assure further that the result of the operation raises no floating- - point exception when converted to the semantic type of the operation. - F.10 Mathematics -1 This subclause contains specifications of facilities that are particularly suited - for IEC 60559 implementations. -2 The Standard C macro HUGE_VAL and its float and long double analogs, - HUGE_VALF and HUGE_VALL, expand to expressions whose values are positive - infinities. -3 Special cases for functions in are covered directly or indirectly by - IEC 60559. The functions that IEC 60559 specifies directly are identified in F.3. The - other functions in treat infinities, NaNs, signed zeros, subnormals, and - (provided the state of the FENV_ACCESS pragma is ''on'') the floating-point status flags - in a manner consistent with the basic arithmetic operations covered by IEC 60559. -4 The expression math_errhandling & MATH_ERREXCEPT shall evaluate to a - nonzero value. -5 The ''invalid'' and ''divide-by-zero'' floating-point exceptions are raised as specified in - subsequent subclauses of this annex. -6 The ''overflow'' floating-point exception is raised whenever an infinity -- or, because of - rounding direction, a maximal-magnitude finite number -- is returned in lieu of a value - whose magnitude is too large. -7 The ''underflow'' floating-point exception is raised whenever a result is tiny (essentially - subnormal or zero) and suffers loss of accuracy.353) - - - 352) 0 - 0 yields -0 instead of +0 just when the rounding direction is downward. - 353) IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on - when the floating-point exception is raised. - -[page 513] - -8 Whether or when library functions raise the ''inexact'' floating-point exception is - unspecified, unless explicitly specified otherwise. -9 Whether or when library functions raise an undeserved ''underflow'' floating-point - exception is unspecified.354) Otherwise, as implied by F.8.6, the functions do - not raise spurious floating-point exceptions (detectable by the user), other than the - ''inexact'' floating-point exception. -10 Whether the functions honor the rounding direction mode is implementation-defined, - unless explicitly specified otherwise. -11 Functions with a NaN argument return a NaN result and raise no floating-point exception, - except where stated otherwise. -12 The specifications in the following subclauses append to the definitions in . - For families of functions, the specifications apply to all of the functions even though only - the principal function is shown. Unless otherwise specified, where the symbol ''(+-)'' - occurs in both an argument and the result, the result has the same sign as the argument. - Recommended practice -13 If a function with one or more NaN arguments returns a NaN result, the result should be - the same as one of the NaN arguments (after possible type conversion), except perhaps - for the sign. - F.10.1 Trigonometric functions - F.10.1.1 The acos functions -1 -- acos(1) returns +0. - -- acos(x) returns a NaN and raises the ''invalid'' floating-point exception for - | x | > 1. - F.10.1.2 The asin functions -1 -- asin((+-)0) returns (+-)0. - -- asin(x) returns a NaN and raises the ''invalid'' floating-point exception for - | x | > 1. - - - - - 354) It is intended that undeserved ''underflow'' and ''inexact'' floating-point exceptions are raised only if - avoiding them would be too costly. - -[page 514] - - F.10.1.3 The atan functions -1 -- atan((+-)0) returns (+-)0. - -- atan((+-)(inf)) returns (+-)pi /2. - F.10.1.4 The atan2 functions -1 -- atan2((+-)0, -0) returns (+-)pi .355) - -- atan2((+-)0, +0) returns (+-)0. - -- atan2((+-)0, x) returns (+-)pi for x < 0. - -- atan2((+-)0, x) returns (+-)0 for x > 0. - -- atan2(y, (+-)0) returns -pi /2 for y < 0. - -- atan2(y, (+-)0) returns pi /2 for y > 0. - -- atan2((+-)y, -(inf)) returns (+-)pi for finite y > 0. - -- atan2((+-)y, +(inf)) returns (+-)0 for finite y > 0. - -- atan2((+-)(inf), x) returns (+-)pi /2 for finite x. - -- atan2((+-)(inf), -(inf)) returns (+-)3pi /4. - -- atan2((+-)(inf), +(inf)) returns (+-)pi /4. - F.10.1.5 The cos functions -1 -- cos((+-)0) returns 1. - -- cos((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception. - F.10.1.6 The sin functions -1 -- sin((+-)0) returns (+-)0. - -- sin((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception. - F.10.1.7 The tan functions -1 -- tan((+-)0) returns (+-)0. - -- tan((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception. - - - - - 355) atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise - the ''divide-by-zero'' floating-point exception. - -[page 515] - - F.10.2 Hyperbolic functions - F.10.2.1 The acosh functions -1 -- acosh(1) returns +0. - -- acosh(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 1. - -- acosh(+(inf)) returns +(inf). - F.10.2.2 The asinh functions -1 -- asinh((+-)0) returns (+-)0. - -- asinh((+-)(inf)) returns (+-)(inf). - F.10.2.3 The atanh functions -1 -- atanh((+-)0) returns (+-)0. - -- atanh((+-)1) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception. - -- atanh(x) returns a NaN and raises the ''invalid'' floating-point exception for - | x | > 1. - F.10.2.4 The cosh functions -1 -- cosh((+-)0) returns 1. - -- cosh((+-)(inf)) returns +(inf). - F.10.2.5 The sinh functions -1 -- sinh((+-)0) returns (+-)0. - -- sinh((+-)(inf)) returns (+-)(inf). - F.10.2.6 The tanh functions -1 -- tanh((+-)0) returns (+-)0. - -- tanh((+-)(inf)) returns (+-)1. - F.10.3 Exponential and logarithmic functions - F.10.3.1 The exp functions -1 -- exp((+-)0) returns 1. - -- exp(-(inf)) returns +0. - -- exp(+(inf)) returns +(inf). - - - - -[page 516] - - F.10.3.2 The exp2 functions -1 -- exp2((+-)0) returns 1. - -- exp2(-(inf)) returns +0. - -- exp2(+(inf)) returns +(inf). - F.10.3.3 The expm1 functions -1 -- expm1((+-)0) returns (+-)0. - -- expm1(-(inf)) returns -1. - -- expm1(+(inf)) returns +(inf). - F.10.3.4 The frexp functions -1 -- frexp((+-)0, exp) returns (+-)0, and stores 0 in the object pointed to by exp. - -- frexp((+-)(inf), exp) returns (+-)(inf), and stores an unspecified value in the object - pointed to by exp. - -- frexp(NaN, exp) stores an unspecified value in the object pointed to by exp - (and returns a NaN). -2 frexp raises no floating-point exceptions. -3 When the radix of the argument is a power of 2, the returned value is exact and is - independent of the current rounding direction mode. -4 On a binary system, the body of the frexp function might be - { - *exp = (value == 0) ? 0 : (int)(1 + logb(value)); - return scalbn(value, -(*exp)); - } - F.10.3.5 The ilogb functions -1 When the correct result is representable in the range of the return type, the returned value - is exact and is independent of the current rounding direction mode. -2 If the correct result is outside the range of the return type, the numeric result is - unspecified and the ''invalid'' floating-point exception is raised. - - - - -[page 517] - - F.10.3.6 The ldexp functions -1 On a binary system, ldexp(x, exp) is equivalent to scalbn(x, exp). - F.10.3.7 The log functions -1 -- log((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception. - -- log(1) returns +0. - -- log(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 0. - -- log(+(inf)) returns +(inf). - F.10.3.8 The log10 functions -1 -- log10((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception. - -- log10(1) returns +0. - -- log10(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 0. - -- log10(+(inf)) returns +(inf). - F.10.3.9 The log1p functions -1 -- log1p((+-)0) returns (+-)0. - -- log1p(-1) returns -(inf) and raises the ''divide-by-zero'' floating-point exception. - -- log1p(x) returns a NaN and raises the ''invalid'' floating-point exception for - x < -1. - -- log1p(+(inf)) returns +(inf). - F.10.3.10 The log2 functions -1 -- log2((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception. - -- log2(1) returns +0. - -- log2(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 0. - -- log2(+(inf)) returns +(inf). - F.10.3.11 The logb functions -1 -- logb((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception. - -- logb((+-)(inf)) returns +(inf). -2 The returned value is exact and is independent of the current rounding direction mode. - - - - -[page 518] - - F.10.3.12 The modf functions -1 -- modf((+-)x, iptr) returns a result with the same sign as x. - -- modf((+-)(inf), iptr) returns (+-)0 and stores (+-)(inf) in the object pointed to by iptr. - -- modf(NaN, iptr) stores a NaN in the object pointed to by iptr (and returns a - NaN). -2 The returned values are exact and are independent of the current rounding direction - mode. -3 modf behaves as though implemented by - #include - #include - #pragma STDC FENV_ACCESS ON - double modf(double value, double *iptr) - { - int save_round = fegetround(); - fesetround(FE_TOWARDZERO); - *iptr = nearbyint(value); - fesetround(save_round); - return copysign( - isinf(value) ? 0.0 : - value - (*iptr), value); - } - F.10.3.13 The scalbn and scalbln functions -1 -- scalbn((+-)0, n) returns (+-)0. - -- scalbn(x, 0) returns x. - -- scalbn((+-)(inf), n) returns (+-)(inf). - F.10.4 Power and absolute value functions - F.10.4.1 The cbrt functions -1 -- cbrt((+-)0) returns (+-)0. - -- cbrt((+-)(inf)) returns (+-)(inf). - - - - -[page 519] - - F.10.4.2 The fabs functions -1 -- fabs((+-)0) returns +0. - -- fabs((+-)(inf)) returns +(inf). -2 The returned value is exact and is independent of the current rounding direction mode. - F.10.4.3 The hypot functions -1 -- hypot(x, y), hypot(y, x), and hypot(x, -y) are equivalent. - -- hypot(x, (+-)0) is equivalent to fabs(x). - -- hypot((+-)(inf), y) returns +(inf), even if y is a NaN. - F.10.4.4 The pow functions -1 -- pow((+-)0, y) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception - for y an odd integer < 0. - -- pow((+-)0, y) returns +(inf) and raises the ''divide-by-zero'' floating-point exception - for y < 0 and not an odd integer. - -- pow((+-)0, y) returns (+-)0 for y an odd integer > 0. - -- pow((+-)0, y) returns +0 for y > 0 and not an odd integer. - -- pow(-1, (+-)(inf)) returns 1. - -- pow(+1, y) returns 1 for any y, even a NaN. - -- pow(x, (+-)0) returns 1 for any x, even a NaN. - -- pow(x, y) returns a NaN and raises the ''invalid'' floating-point exception for - finite x < 0 and finite non-integer y. - -- pow(x, -(inf)) returns +(inf) for | x | < 1. - -- pow(x, -(inf)) returns +0 for | x | > 1. - -- pow(x, +(inf)) returns +0 for | x | < 1. - -- pow(x, +(inf)) returns +(inf) for | x | > 1. - -- pow(-(inf), y) returns -0 for y an odd integer < 0. - -- pow(-(inf), y) returns +0 for y < 0 and not an odd integer. - -- pow(-(inf), y) returns -(inf) for y an odd integer > 0. - -- pow(-(inf), y) returns +(inf) for y > 0 and not an odd integer. - -- pow(+(inf), y) returns +0 for y < 0. - -- pow(+(inf), y) returns +(inf) for y > 0. - - -[page 520] - - F.10.4.5 The sqrt functions -1 sqrt is fully specified as a basic arithmetic operation in IEC 60559. The returned value - is dependent on the current rounding direction mode. - F.10.5 Error and gamma functions - F.10.5.1 The erf functions -1 -- erf((+-)0) returns (+-)0. - -- erf((+-)(inf)) returns (+-)1. - F.10.5.2 The erfc functions -1 -- erfc(-(inf)) returns 2. - -- erfc(+(inf)) returns +0. - F.10.5.3 The lgamma functions -1 -- lgamma(1) returns +0. - -- lgamma(2) returns +0. - -- lgamma(x) returns +(inf) and raises the ''divide-by-zero'' floating-point exception for - x a negative integer or zero. - -- lgamma(-(inf)) returns +(inf). - -- lgamma(+(inf)) returns +(inf). - F.10.5.4 The tgamma functions -1 -- tgamma((+-)0) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception. - -- tgamma(x) returns a NaN and raises the ''invalid'' floating-point exception for x a - negative integer. - -- tgamma(-(inf)) returns a NaN and raises the ''invalid'' floating-point exception. - -- tgamma(+(inf)) returns +(inf). - F.10.6 Nearest integer functions - F.10.6.1 The ceil functions -1 -- ceil((+-)0) returns (+-)0. - -- ceil((+-)(inf)) returns (+-)(inf). -2 The returned value is exact and is independent of the current rounding direction mode. -3 The double version of ceil behaves as though implemented by - - - -[page 521] - - #include - #include - #pragma STDC FENV_ACCESS ON - double ceil(double x) - { - double result; - int save_round = fegetround(); - fesetround(FE_UPWARD); - result = rint(x); // or nearbyint instead of rint - fesetround(save_round); - return result; - } - F.10.6.2 The floor functions -1 -- floor((+-)0) returns (+-)0. - -- floor((+-)(inf)) returns (+-)(inf). -2 The returned value is exact and is independent of the current rounding direction mode. -3 See the sample implementation for ceil in F.10.6.1. - F.10.6.3 The nearbyint functions -1 The nearbyint functions use IEC 60559 rounding according to the current rounding - direction. They do not raise the ''inexact'' floating-point exception if the result differs in - value from the argument. - -- nearbyint((+-)0) returns (+-)0 (for all rounding directions). - -- nearbyint((+-)(inf)) returns (+-)(inf) (for all rounding directions). - F.10.6.4 The rint functions -1 The rint functions differ from the nearbyint functions only in that they do raise the - ''inexact'' floating-point exception if the result differs in value from the argument. - F.10.6.5 The lrint and llrint functions -1 The lrint and llrint functions provide floating-to-integer conversion as prescribed - by IEC 60559. They round according to the current rounding direction. If the rounded - value is outside the range of the return type, the numeric result is unspecified and the - ''invalid'' floating-point exception is raised. When they raise no other floating-point - exception and the result differs from the argument, they raise the ''inexact'' floating-point - exception. - - - - -[page 522] - - F.10.6.6 The round functions -1 -- round((+-)0) returns (+-)0. - -- round((+-)(inf)) returns (+-)(inf). -2 The double version of round behaves as though implemented by - #include - #include - #pragma STDC FENV_ACCESS ON - double round(double x) - { - double result; - fenv_t save_env; - feholdexcept(&save_env); - result = rint(x); - if (fetestexcept(FE_INEXACT)) { - fesetround(FE_TOWARDZERO); - result = rint(copysign(0.5 + fabs(x), x)); - } - feupdateenv(&save_env); - return result; - } - The round functions may, but are not required to, raise the ''inexact'' floating-point - exception for non-integer numeric arguments, as this implementation does. - F.10.6.7 The lround and llround functions -1 The lround and llround functions differ from the lrint and llrint functions - with the default rounding direction just in that the lround and llround functions - round halfway cases away from zero and need not raise the ''inexact'' floating-point - exception for non-integer arguments that round to within the range of the return type. - F.10.6.8 The trunc functions -1 The trunc functions use IEC 60559 rounding toward zero (regardless of the current - rounding direction). The returned value is exact. - -- trunc((+-)0) returns (+-)0. - -- trunc((+-)(inf)) returns (+-)(inf). - - - - -[page 523] - - F.10.7 Remainder functions - F.10.7.1 The fmod functions -1 -- fmod((+-)0, y) returns (+-)0 for y not zero. - -- fmod(x, y) returns a NaN and raises the ''invalid'' floating-point exception for x - infinite or y zero. - -- fmod(x, (+-)(inf)) returns x for x not infinite. -2 When subnormal results are supported, the returned value is exact and is independent of - the current rounding direction mode. -3 The double version of fmod behaves as though implemented by - #include - #include - #pragma STDC FENV_ACCESS ON - double fmod(double x, double y) - { - double result; - result = remainder(fabs(x), (y = fabs(y))); - if (signbit(result)) result += y; - return copysign(result, x); - } - F.10.7.2 The remainder functions -1 The remainder functions are fully specified as a basic arithmetic operation in - IEC 60559. -2 When subnormal results are supported, the returned value is exact and is independent of - the current rounding direction mode. - F.10.7.3 The remquo functions -1 The remquo functions follow the specifications for the remainder functions. They - have no further specifications special to IEC 60559 implementations. -2 When subnormal results are supported, the returned value is exact and is independent of - the current rounding direction mode. - - - - -[page 524] - - F.10.8 Manipulation functions - F.10.8.1 The copysign functions -1 copysign is specified in the Appendix to IEC 60559. -2 The returned value is exact and is independent of the current rounding direction mode. - F.10.8.2 The nan functions -1 All IEC 60559 implementations support quiet NaNs, in all floating formats. -2 The returned value is exact and is independent of the current rounding direction mode. - F.10.8.3 The nextafter functions -1 -- nextafter(x, y) raises the ''overflow'' and ''inexact'' floating-point exceptions - for x finite and the function value infinite. - -- nextafter(x, y) raises the ''underflow'' and ''inexact'' floating-point - exceptions for the function value subnormal or zero and x != y. -2 Even though underflow or overflow can occur, the returned value is independent of the - current rounding direction mode. - F.10.8.4 The nexttoward functions -1 No additional requirements beyond those on nextafter. -2 Even though underflow or overflow can occur, the returned value is independent of the - current rounding direction mode. - F.10.9 Maximum, minimum, and positive difference functions - F.10.9.1 The fdim functions -1 No additional requirements. - F.10.9.2 The fmax functions -1 If just one argument is a NaN, the fmax functions return the other argument (if both - arguments are NaNs, the functions return a NaN). -2 The returned value is exact and is independent of the current rounding direction mode. -3 The body of the fmax function might be356) - { return (isgreaterequal(x, y) || - isnan(y)) ? x : y; } - - - - 356) Ideally, fmax would be sensitive to the sign of zero, for example fmax(-0.0, +0.0) would - return +0; however, implementation in software might be impractical. - -[page 525] - - F.10.9.3 The fmin functions -1 The fmin functions are analogous to the fmax functions (see F.10.9.2). -2 The returned value is exact and is independent of the current rounding direction mode. - F.10.10 Floating multiply-add - F.10.10.1 The fma functions -1 -- fma(x, y, z) computes xy + z, correctly rounded once. - -- fma(x, y, z) returns a NaN and optionally raises the ''invalid'' floating-point - exception if one of x and y is infinite, the other is zero, and z is a NaN. - -- fma(x, y, z) returns a NaN and raises the ''invalid'' floating-point exception if - one of x and y is infinite, the other is zero, and z is not a NaN. - -- fma(x, y, z) returns a NaN and raises the ''invalid'' floating-point exception if x - times y is an exact infinity and z is also an infinity but with the opposite sign. - F.10.11 Comparison macros -1 Relational operators and their corresponding comparison macros (7.12.14) produce - equivalent result values, even if argument values are represented in wider formats. Thus, - comparison macro arguments represented in formats wider than their semantic types are - not converted to the semantic types, unless the wide evaluation method converts operands - of relational operators to their semantic types. The standard wide evaluation methods - characterized by FLT_EVAL_METHOD equal to 1 or 2 (5.2.4.2.2), do not convert - operands of relational operators to their semantic types. - - - - -[page 526] - - Annex G - (informative) - IEC 60559-compatible complex arithmetic - G.1 Introduction -1 This annex supplements annex F to specify complex arithmetic for compatibility with - IEC 60559 real floating-point arithmetic. Although these specifications have been - carefully designed, there is little existing practice to validate the design decisions. - Therefore, these specifications are not normative, but should be viewed more as - recommended practice. An implementation that defines - __STDC_IEC_559_COMPLEX__ should conform to the specifications in this annex. - G.2 Types -1 There is a new keyword _Imaginary, which is used to specify imaginary types. It is - used as a type specifier within declaration specifiers in the same way as _Complex is - (thus, _Imaginary float is a valid type name). -2 There are three imaginary types, designated as float _Imaginary, double - _Imaginary, and long double _Imaginary. The imaginary types (along with - the real floating and complex types) are floating types. -3 For imaginary types, the corresponding real type is given by deleting the keyword - _Imaginary from the type name. -4 Each imaginary type has the same representation and alignment requirements as the - corresponding real type. The value of an object of imaginary type is the value of the real - representation times the imaginary unit. -5 The imaginary type domain comprises the imaginary types. - G.3 Conventions -1 A complex or imaginary value with at least one infinite part is regarded as an infinity - (even if its other part is a NaN). A complex or imaginary value is a finite number if each - of its parts is a finite number (neither infinite nor NaN). A complex or imaginary value is - a zero if each of its parts is a zero. - - - - -[page 527] - - G.4 Conversions - G.4.1 Imaginary types -1 Conversions among imaginary types follow rules analogous to those for real floating - types. - G.4.2 Real and imaginary -1 When a value of imaginary type is converted to a real type other than _Bool,357) the - result is a positive zero. -2 When a value of real type is converted to an imaginary type, the result is a positive - imaginary zero. - G.4.3 Imaginary and complex -1 When a value of imaginary type is converted to a complex type, the real part of the - complex result value is a positive zero and the imaginary part of the complex result value - is determined by the conversion rules for the corresponding real types. -2 When a value of complex type is converted to an imaginary type, the real part of the - complex value is discarded and the value of the imaginary part is converted according to - the conversion rules for the corresponding real types. - G.5 Binary operators -1 The following subclauses supplement 6.5 in order to specify the type of the result for an - operation with an imaginary operand. -2 For most operand types, the value of the result of a binary operator with an imaginary or - complex operand is completely determined, with reference to real arithmetic, by the usual - mathematical formula. For some operand types, the usual mathematical formula is - problematic because of its treatment of infinities and because of undue overflow or - underflow; in these cases the result satisfies certain properties (specified in G.5.1), but is - not completely determined. - - - - - 357) See 6.3.1.2. - -[page 528] - - G.5.1 Multiplicative operators - Semantics -1 If one operand has real type and the other operand has imaginary type, then the result has - imaginary type. If both operands have imaginary type, then the result has real type. (If - either operand has complex type, then the result has complex type.) -2 If the operands are not both complex, then the result and floating-point exception - behavior of the * operator is defined by the usual mathematical formula: - * u iv u + iv - - x xu i(xv) (xu) + i(xv) - - iy i(yu) -yv (-yv) + i(yu) - - x + iy (xu) + i(yu) (-yv) + i(xv) -3 If the second operand is not complex, then the result and floating-point exception - behavior of the / operator is defined by the usual mathematical formula: - / u iv - - x x/u i(-x/v) - - iy i(y/u) y/v - - x + iy (x/u) + i(y/u) (y/v) + i(-x/v) -4 The * and / operators satisfy the following infinity properties for all real, imaginary, and - complex operands:358) - -- if one operand is an infinity and the other operand is a nonzero finite number or an - infinity, then the result of the * operator is an infinity; - -- if the first operand is an infinity and the second operand is a finite number, then the - result of the / operator is an infinity; - -- if the first operand is a finite number and the second operand is an infinity, then the - result of the / operator is a zero; - - - - - 358) These properties are already implied for those cases covered in the tables, but are required for all cases - (at least where the state for CX_LIMITED_RANGE is ''off''). - -[page 529] - - -- if the first operand is a nonzero finite number or an infinity and the second operand is - a zero, then the result of the / operator is an infinity. -5 If both operands of the * operator are complex or if the second operand of the / operator - is complex, the operator raises floating-point exceptions if appropriate for the calculation - of the parts of the result, and may raise spurious floating-point exceptions. -6 EXAMPLE 1 Multiplication of double _Complex operands could be implemented as follows. Note - that the imaginary unit I has imaginary type (see G.6). - #include - #include - /* Multiply z * w ... */ - double complex _Cmultd(double complex z, double complex w) - { - #pragma STDC FP_CONTRACT OFF - double a, b, c, d, ac, bd, ad, bc, x, y; - a = creal(z); b = cimag(z); - c = creal(w); d = cimag(w); - ac = a * c; bd = b * d; - ad = a * d; bc = b * c; - x = ac - bd; y = ad + bc; - if (isnan(x) && isnan(y)) { - /* Recover infinities that computed as NaN+iNaN ... */ - int recalc = 0; - if ( isinf(a) || isinf(b) ) { // z is infinite - /* "Box" the infinity and change NaNs in the other factor to 0 */ - a = copysign(isinf(a) ? 1.0 : 0.0, a); - b = copysign(isinf(b) ? 1.0 : 0.0, b); - if (isnan(c)) c = copysign(0.0, c); - if (isnan(d)) d = copysign(0.0, d); - recalc = 1; - } - if ( isinf(c) || isinf(d) ) { // w is infinite - /* "Box" the infinity and change NaNs in the other factor to 0 */ - c = copysign(isinf(c) ? 1.0 : 0.0, c); - d = copysign(isinf(d) ? 1.0 : 0.0, d); - if (isnan(a)) a = copysign(0.0, a); - if (isnan(b)) b = copysign(0.0, b); - recalc = 1; - } - if (!recalc && (isinf(ac) || isinf(bd) || - isinf(ad) || isinf(bc))) { - /* Recover infinities from overflow by changing NaNs to 0 ... */ - if (isnan(a)) a = copysign(0.0, a); - if (isnan(b)) b = copysign(0.0, b); - if (isnan(c)) c = copysign(0.0, c); - if (isnan(d)) d = copysign(0.0, d); - recalc = 1; - } - if (recalc) { - -[page 530] - - x = INFINITY * ( a * c - b * d ); - y = INFINITY * ( a * d + b * c ); - } - } - return x + I * y; - } -7 This implementation achieves the required treatment of infinities at the cost of only one isnan test in - ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur. - -8 EXAMPLE 2 Division of two double _Complex operands could be implemented as follows. - #include - #include - /* Divide z / w ... */ - double complex _Cdivd(double complex z, double complex w) - { - #pragma STDC FP_CONTRACT OFF - double a, b, c, d, logbw, denom, x, y; - int ilogbw = 0; - a = creal(z); b = cimag(z); - c = creal(w); d = cimag(w); - logbw = logb(fmax(fabs(c), fabs(d))); - if (isfinite(logbw)) { - ilogbw = (int)logbw; - c = scalbn(c, -ilogbw); d = scalbn(d, -ilogbw); - } - denom = c * c + d * d; - x = scalbn((a * c + b * d) / denom, -ilogbw); - y = scalbn((b * c - a * d) / denom, -ilogbw); - /* Recover infinities and zeros that computed as NaN+iNaN; */ - /* the only cases are nonzero/zero, infinite/finite, and finite/infinite, ... */ - if (isnan(x) && isnan(y)) { - if ((denom == 0.0) && - (!isnan(a) || !isnan(b))) { - x = copysign(INFINITY, c) * a; - y = copysign(INFINITY, c) * b; - } - else if ((isinf(a) || isinf(b)) && - isfinite(c) && isfinite(d)) { - a = copysign(isinf(a) ? 1.0 : 0.0, a); - b = copysign(isinf(b) ? 1.0 : 0.0, b); - x = INFINITY * ( a * c + b * d ); - y = INFINITY * ( b * c - a * d ); - } - else if (isinf(logbw) && - isfinite(a) && isfinite(b)) { - c = copysign(isinf(c) ? 1.0 : 0.0, c); - d = copysign(isinf(d) ? 1.0 : 0.0, d); - x = 0.0 * ( a * c + b * d ); - y = 0.0 * ( b * c - a * d ); - -[page 531] - - } - } - return x + I * y; - } -9 Scaling the denominator alleviates the main overflow and underflow problem, which is more serious than - for multiplication. In the spirit of the multiplication example above, this code does not defend against - overflow and underflow in the calculation of the numerator. Scaling with the scalbn function, instead of - with division, provides better roundoff characteristics. - - G.5.2 Additive operators - Semantics -1 If both operands have imaginary type, then the result has imaginary type. (If one operand - has real type and the other operand has imaginary type, or if either operand has complex - type, then the result has complex type.) -2 In all cases the result and floating-point exception behavior of a + or - operator is defined - by the usual mathematical formula: - + or - u iv u + iv - - x x(+-)u x (+-) iv (x (+-) u) (+-) iv - - iy (+-)u + iy i(y (+-) v) (+-)u + i(y (+-) v) - - x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v) - G.6 Complex arithmetic -1 The macros - imaginary - and - _Imaginary_I - are defined, respectively, as _Imaginary and a constant expression of type const - float _Imaginary with the value of the imaginary unit. The macro - I - is defined to be _Imaginary_I (not _Complex_I as stated in 7.3). Notwithstanding - the provisions of 7.1.3, a program may undefine and then perhaps redefine the macro - imaginary. -2 This subclause contains specifications for the functions that are - particularly suited to IEC 60559 implementations. For families of functions, the - specifications apply to all of the functions even though only the principal function is - -[page 532] - - shown. Unless otherwise specified, where the symbol ''(+-)'' occurs in both an argument - and the result, the result has the same sign as the argument. -3 The functions are continuous onto both sides of their branch cuts, taking into account the - sign of zero. For example, csqrt(-2 (+-) i0) = (+-)isqrt:2. - -4 Since complex and imaginary values are composed of real values, each function may be - regarded as computing real values from real values. Except as noted, the functions treat - real infinities, NaNs, signed zeros, subnormals, and the floating-point exception flags in a - manner consistent with the specifications for real functions in F.10.359) -5 The functions cimag, conj, cproj, and creal are fully specified for all - implementations, including IEC 60559 ones, in 7.3.9. These functions raise no floating- - point exceptions. -6 Each of the functions cabs and carg is specified by a formula in terms of a real - function (whose special cases are covered in annex F): - cabs(x + iy) = hypot(x, y) - carg(x + iy) = atan2(y, x) -7 Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by - a formula in terms of other complex functions (whose special cases are specified below): - casin(z) = -i casinh(iz) - catan(z) = -i catanh(iz) - ccos(z) = ccosh(iz) - csin(z) = -i csinh(iz) - ctan(z) = -i ctanh(iz) -8 For the other functions, the following subclauses specify behavior for special cases, - including treatment of the ''invalid'' and ''divide-by-zero'' floating-point exceptions. For - families of functions, the specifications apply to all of the functions even though only the - principal function is shown. For a function f satisfying f (conj(z)) = conj( f (z)), the - specifications for the upper half-plane imply the specifications for the lower half-plane; if - the function f is also either even, f (-z) = f (z), or odd, f (-z) = - f (z), then the - specifications for the first quadrant imply the specifications for the other three quadrants. -9 In the following subclauses, cis(y) is defined as cos(y) + i sin(y). - - - - - 359) As noted in G.3, a complex value with at least one infinite part is regarded as an infinity even if its - other part is a NaN. - -[page 533] - - G.6.1 Trigonometric functions - G.6.1.1 The cacos functions -1 -- cacos(conj(z)) = conj(cacos(z)). - -- cacos((+-)0 + i0) returns pi /2 - i0. - -- cacos((+-)0 + iNaN) returns pi /2 + iNaN. - -- cacos(x + i (inf)) returns pi /2 - i (inf), for finite x. - -- cacos(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for nonzero finite x. - -- cacos(-(inf) + iy) returns pi - i (inf), for positive-signed finite y. - -- cacos(+(inf) + iy) returns +0 - i (inf), for positive-signed finite y. - -- cacos(-(inf) + i (inf)) returns 3pi /4 - i (inf). - -- cacos(+(inf) + i (inf)) returns pi /4 - i (inf). - -- cacos((+-)(inf) + iNaN) returns NaN (+-) i (inf) (where the sign of the imaginary part of the - result is unspecified). - -- cacos(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite y. - -- cacos(NaN + i (inf)) returns NaN - i (inf). - -- cacos(NaN + iNaN) returns NaN + iNaN. - G.6.2 Hyperbolic functions - G.6.2.1 The cacosh functions -1 -- cacosh(conj(z)) = conj(cacosh(z)). - -- cacosh((+-)0 + i0) returns +0 + ipi /2. - -- cacosh(x + i (inf)) returns +(inf) + ipi /2, for finite x. - -- cacosh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' - floating-point exception, for finite x. - -- cacosh(-(inf) + iy) returns +(inf) + ipi , for positive-signed finite y. - -- cacosh(+(inf) + iy) returns +(inf) + i0, for positive-signed finite y. - -- cacosh(-(inf) + i (inf)) returns +(inf) + i3pi /4. - -- cacosh(+(inf) + i (inf)) returns +(inf) + ipi /4. - -- cacosh((+-)(inf) + iNaN) returns +(inf) + iNaN. - - -[page 534] - - -- cacosh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' - floating-point exception, for finite y. - -- cacosh(NaN + i (inf)) returns +(inf) + iNaN. - -- cacosh(NaN + iNaN) returns NaN + iNaN. - G.6.2.2 The casinh functions -1 -- casinh(conj(z)) = conj(casinh(z)) and casinh is odd. - -- casinh(+0 + i0) returns 0 + i0. - -- casinh(x + i (inf)) returns +(inf) + ipi /2 for positive-signed finite x. - -- casinh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' - floating-point exception, for finite x. - -- casinh(+(inf) + iy) returns +(inf) + i0 for positive-signed finite y. - -- casinh(+(inf) + i (inf)) returns +(inf) + ipi /4. - -- casinh(+(inf) + iNaN) returns +(inf) + iNaN. - -- casinh(NaN + i0) returns NaN + i0. - -- casinh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' - floating-point exception, for finite nonzero y. - -- casinh(NaN + i (inf)) returns (+-)(inf) + iNaN (where the sign of the real part of the result - is unspecified). - -- casinh(NaN + iNaN) returns NaN + iNaN. - G.6.2.3 The catanh functions -1 -- catanh(conj(z)) = conj(catanh(z)) and catanh is odd. - -- catanh(+0 + i0) returns +0 + i0. - -- catanh(+0 + iNaN) returns +0 + iNaN. - -- catanh(+1 + i0) returns +(inf) + i0 and raises the ''divide-by-zero'' floating-point - exception. - -- catanh(x + i (inf)) returns +0 + ipi /2, for finite positive-signed x. - -- catanh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' - floating-point exception, for nonzero finite x. - -- catanh(+(inf) + iy) returns +0 + ipi /2, for finite positive-signed y. - -- catanh(+(inf) + i (inf)) returns +0 + ipi /2. - -- catanh(+(inf) + iNaN) returns +0 + iNaN. - -[page 535] - - -- catanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' - floating-point exception, for finite y. - -- catanh(NaN + i (inf)) returns (+-)0 + ipi /2 (where the sign of the real part of the result is - unspecified). - -- catanh(NaN + iNaN) returns NaN + iNaN. - G.6.2.4 The ccosh functions -1 -- ccosh(conj(z)) = conj(ccosh(z)) and ccosh is even. - -- ccosh(+0 + i0) returns 1 + i0. - -- ccosh(+0 + i (inf)) returns NaN (+-) i0 (where the sign of the imaginary part of the - result is unspecified) and raises the ''invalid'' floating-point exception. - -- ccosh(+0 + iNaN) returns NaN (+-) i0 (where the sign of the imaginary part of the - result is unspecified). - -- ccosh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point - exception, for finite nonzero x. - -- ccosh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite nonzero x. - -- ccosh(+(inf) + i0) returns +(inf) + i0. - -- ccosh(+(inf) + iy) returns +(inf) cis(y), for finite nonzero y. - -- ccosh(+(inf) + i (inf)) returns (+-)(inf) + iNaN (where the sign of the real part of the result is - unspecified) and raises the ''invalid'' floating-point exception. - -- ccosh(+(inf) + iNaN) returns +(inf) + iNaN. - -- ccosh(NaN + i0) returns NaN (+-) i0 (where the sign of the imaginary part of the - result is unspecified). - -- ccosh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for all nonzero numbers y. - -- ccosh(NaN + iNaN) returns NaN + iNaN. - G.6.2.5 The csinh functions -1 -- csinh(conj(z)) = conj(csinh(z)) and csinh is odd. - -- csinh(+0 + i0) returns +0 + i0. - -- csinh(+0 + i (inf)) returns (+-)0 + iNaN (where the sign of the real part of the result is - unspecified) and raises the ''invalid'' floating-point exception. - -- csinh(+0 + iNaN) returns (+-)0 + iNaN (where the sign of the real part of the result is - unspecified). -[page 536] - - -- csinh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point - exception, for positive finite x. - -- csinh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite nonzero x. - -- csinh(+(inf) + i0) returns +(inf) + i0. - -- csinh(+(inf) + iy) returns +(inf) cis(y), for positive finite y. - -- csinh(+(inf) + i (inf)) returns (+-)(inf) + iNaN (where the sign of the real part of the result is - unspecified) and raises the ''invalid'' floating-point exception. - -- csinh(+(inf) + iNaN) returns (+-)(inf) + iNaN (where the sign of the real part of the result - is unspecified). - -- csinh(NaN + i0) returns NaN + i0. - -- csinh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for all nonzero numbers y. - -- csinh(NaN + iNaN) returns NaN + iNaN. - G.6.2.6 The ctanh functions -1 -- ctanh(conj(z)) = conj(ctanh(z))and ctanh is odd. - -- ctanh(+0 + i0) returns +0 + i0. - -- ctanh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point - exception, for finite x. - -- ctanh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite x. - -- ctanh(+(inf) + iy) returns 1 + i0 sin(2y), for positive-signed finite y. - -- ctanh(+(inf) + i (inf)) returns 1 (+-) i0 (where the sign of the imaginary part of the result - is unspecified). - -- ctanh(+(inf) + iNaN) returns 1 (+-) i0 (where the sign of the imaginary part of the - result is unspecified). - -- ctanh(NaN + i0) returns NaN + i0. - -- ctanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for all nonzero numbers y. - -- ctanh(NaN + iNaN) returns NaN + iNaN. - - - - -[page 537] - - G.6.3 Exponential and logarithmic functions - G.6.3.1 The cexp functions -1 -- cexp(conj(z)) = conj(cexp(z)). - -- cexp((+-)0 + i0) returns 1 + i0. - -- cexp(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point - exception, for finite x. - -- cexp(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite x. - -- cexp(+(inf) + i0) returns +(inf) + i0. - -- cexp(-(inf) + iy) returns +0 cis(y), for finite y. - -- cexp(+(inf) + iy) returns +(inf) cis(y), for finite nonzero y. - -- cexp(-(inf) + i (inf)) returns (+-)0 (+-) i0 (where the signs of the real and imaginary parts of - the result are unspecified). - -- cexp(+(inf) + i (inf)) returns (+-)(inf) + iNaN and raises the ''invalid'' floating-point - exception (where the sign of the real part of the result is unspecified). - -- cexp(-(inf) + iNaN) returns (+-)0 (+-) i0 (where the signs of the real and imaginary parts - of the result are unspecified). - -- cexp(+(inf) + iNaN) returns (+-)(inf) + iNaN (where the sign of the real part of the result - is unspecified). - -- cexp(NaN + i0) returns NaN + i0. - -- cexp(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for all nonzero numbers y. - -- cexp(NaN + iNaN) returns NaN + iNaN. - G.6.3.2 The clog functions -1 -- clog(conj(z)) = conj(clog(z)). - -- clog(-0 + i0) returns -(inf) + ipi and raises the ''divide-by-zero'' floating-point - exception. - -- clog(+0 + i0) returns -(inf) + i0 and raises the ''divide-by-zero'' floating-point - exception. - -- clog(x + i (inf)) returns +(inf) + ipi /2, for finite x. - -- clog(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite x. - -[page 538] - - -- clog(-(inf) + iy) returns +(inf) + ipi , for finite positive-signed y. - -- clog(+(inf) + iy) returns +(inf) + i0, for finite positive-signed y. - -- clog(-(inf) + i (inf)) returns +(inf) + i3pi /4. - -- clog(+(inf) + i (inf)) returns +(inf) + ipi /4. - -- clog((+-)(inf) + iNaN) returns +(inf) + iNaN. - -- clog(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite y. - -- clog(NaN + i (inf)) returns +(inf) + iNaN. - -- clog(NaN + iNaN) returns NaN + iNaN. - G.6.4 Power and absolute-value functions - G.6.4.1 The cpow functions -1 The cpow functions raise floating-point exceptions if appropriate for the calculation of - the parts of the result, and may raise spurious exceptions.360) - G.6.4.2 The csqrt functions -1 -- csqrt(conj(z)) = conj(csqrt(z)). - -- csqrt((+-)0 + i0) returns +0 + i0. - -- csqrt(x + i (inf)) returns +(inf) + i (inf), for all x (including NaN). - -- csqrt(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite x. - -- csqrt(-(inf) + iy) returns +0 + i (inf), for finite positive-signed y. - -- csqrt(+(inf) + iy) returns +(inf) + i0, for finite positive-signed y. - -- csqrt(-(inf) + iNaN) returns NaN (+-) i (inf) (where the sign of the imaginary part of the - result is unspecified). - -- csqrt(+(inf) + iNaN) returns +(inf) + iNaN. - -- csqrt(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating- - point exception, for finite y. - -- csqrt(NaN + iNaN) returns NaN + iNaN. - - - - - 360) This allows cpow( z , c ) to be implemented as cexp(c clog( z )) without precluding - implementations that treat special cases more carefully. - -[page 539] - - G.7 Type-generic math -1 Type-generic macros that accept complex arguments also accept imaginary arguments. If - an argument is imaginary, the macro expands to an expression whose type is real, - imaginary, or complex, as appropriate for the particular function: if the argument is - imaginary, then the types of cos, cosh, fabs, carg, cimag, and creal are real; the - types of sin, tan, sinh, tanh, asin, atan, asinh, and atanh are imaginary; and - the types of the others are complex. -2 Given an imaginary argument, each of the type-generic macros cos, sin, tan, cosh, - sinh, tanh, asin, atan, asinh, atanh is specified by a formula in terms of real - functions: - cos(iy) = cosh(y) - sin(iy) = i sinh(y) - tan(iy) = i tanh(y) - cosh(iy) = cos(y) - sinh(iy) = i sin(y) - tanh(iy) = i tan(y) - asin(iy) = i asinh(y) - atan(iy) = i atanh(y) - asinh(iy) = i asin(y) - atanh(iy) = i atan(y) - - - - -[page 540] - - Annex H - (informative) - Language independent arithmetic - H.1 Introduction -1 This annex documents the extent to which the C language supports the ISO/IEC 10967-1 - standard for language-independent arithmetic (LIA-1). LIA-1 is more general than - IEC 60559 (annex F) in that it covers integer and diverse floating-point arithmetics. - H.2 Types -1 The relevant C arithmetic types meet the requirements of LIA-1 types if an - implementation adds notification of exceptional arithmetic operations and meets the 1 - unit in the last place (ULP) accuracy requirement (LIA-1 subclause 5.2.8). - H.2.1 Boolean type -1 The LIA-1 data type Boolean is implemented by the C data type bool with values of - true and false, all from . - H.2.2 Integer types -1 The signed C integer types int, long int, long long int, and the corresponding - unsigned types are compatible with LIA-1. If an implementation adds support for the - LIA-1 exceptional values ''integer_overflow'' and ''undefined'', then those types are - LIA-1 conformant types. C's unsigned integer types are ''modulo'' in the LIA-1 sense - in that overflows or out-of-bounds results silently wrap. An implementation that defines - signed integer types as also being modulo need not detect integer overflow, in which case, - only integer divide-by-zero need be detected. -2 The parameters for the integer data types can be accessed by the following: - maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX, - ULLONG_MAX - minint INT_MIN, LONG_MIN, LLONG_MIN -3 The parameter ''bounded'' is always true, and is not provided. The parameter ''minint'' - is always 0 for the unsigned types, and is not provided for those types. - - - - -[page 541] - - H.2.2.1 Integer operations -1 The integer operations on integer types are the following: - addI x + y - subI x - y - mulI x * y - divI, divtI x / y - remI, remtI x % y - negI -x - absI abs(x), labs(x), llabs(x) - eqI x == y - neqI x != y - lssI x < y - leqI x <= y - gtrI x > y - geqI x >= y - where x and y are expressions of the same integer type. - H.2.3 Floating-point types -1 The C floating-point types float, double, and long double are compatible with - LIA-1. If an implementation adds support for the LIA-1 exceptional values - ''underflow'', ''floating_overflow'', and ''"undefined'', then those types are conformant - with LIA-1. An implementation that uses IEC 60559 floating-point formats and - operations (see annex F) along with IEC 60559 status flags and traps has LIA-1 - conformant types. - H.2.3.1 Floating-point parameters -1 The parameters for a floating point data type can be accessed by the following: - r FLT_RADIX - p FLT_MANT_DIG, DBL_MANT_DIG, LDBL_MANT_DIG - emax FLT_MAX_EXP, DBL_MAX_EXP, LDBL_MAX_EXP - emin FLT_MIN_EXP, DBL_MIN_EXP, LDBL_MIN_EXP -2 The derived constants for the floating point types are accessed by the following: - - -[page 542] - - fmax FLT_MAX, DBL_MAX, LDBL_MAX - fminN FLT_MIN, DBL_MIN, LDBL_MIN - epsilon FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON - rnd_style FLT_ROUNDS - H.2.3.2 Floating-point operations -1 The floating-point operations on floating-point types are the following: - addF x + y - subF x - y - mulF x * y - divF x / y - negF -x - absF fabsf(x), fabs(x), fabsl(x) - exponentF 1.f+logbf(x), 1.0+logb(x), 1.L+logbl(x) - scaleF scalbnf(x, n), scalbn(x, n), scalbnl(x, n), - scalblnf(x, li), scalbln(x, li), scalblnl(x, li) - intpartF modff(x, &y), modf(x, &y), modfl(x, &y) - fractpartF modff(x, &y), modf(x, &y), modfl(x, &y) - eqF x == y - neqF x != y - lssF x < y - leqF x <= y - gtrF x > y - geqF x >= y - where x and y are expressions of the same floating point type, n is of type int, and li - is of type long int. - H.2.3.3 Rounding styles -1 The C Standard requires all floating types to use the same radix and rounding style, so - that only one identifier for each is provided to map to LIA-1. -2 The FLT_ROUNDS parameter can be used to indicate the LIA-1 rounding styles: - truncate FLT_ROUNDS == 0 - - -[page 543] - - nearest FLT_ROUNDS == 1 - other FLT_ROUNDS != 0 && FLT_ROUNDS != 1 - provided that an implementation extends FLT_ROUNDS to cover the rounding style used - in all relevant LIA-1 operations, not just addition as in C. - H.2.4 Type conversions -1 The LIA-1 type conversions are the following type casts: - cvtI' (->) I (int)i, (long int)i, (long long int)i, - (unsigned int)i, (unsigned long int)i, - (unsigned long long int)i - cvtF (->) I (int)x, (long int)x, (long long int)x, - (unsigned int)x, (unsigned long int)x, - (unsigned long long int)x - cvtI (->) F (float)i, (double)i, (long double)i - cvtF' (->) F (float)x, (double)x, (long double)x -2 In the above conversions from floating to integer, the use of (cast)x can be replaced with - (cast)round(x), (cast)rint(x), (cast)nearbyint(x), (cast)trunc(x), - (cast)ceil(x), or (cast)floor(x). In addition, C's floating-point to integer - conversion functions, lrint(), llrint(), lround(), and llround(), can be - used. They all meet LIA-1's requirements on floating to integer rounding for in-range - values. For out-of-range values, the conversions shall silently wrap for the modulo types. -3 The fmod() function is useful for doing silent wrapping to unsigned integer types, e.g., - fmod( fabs(rint(x)), 65536.0 ) or (0.0 <= (y = fmod( rint(x), - 65536.0 )) ? y : 65536.0 + y) will compute an integer value in the range 0.0 - to 65535.0 which can then be cast to unsigned short int. But, the - remainder() function is not useful for doing silent wrapping to signed integer types, - e.g., remainder( rint(x), 65536.0 ) will compute an integer value in the - range -32767.0 to +32768.0 which is not, in general, in the range of signed short - int. -4 C's conversions (casts) from floating-point to floating-point can meet LIA-1 - requirements if an implementation uses round-to-nearest (IEC 60559 default). -5 C's conversions (casts) from integer to floating-point can meet LIA-1 requirements if an - implementation uses round-to-nearest. - - - - -[page 544] - - H.3 Notification -1 Notification is the process by which a user or program is informed that an exceptional - arithmetic operation has occurred. C's operations are compatible with LIA-1 in that C - allows an implementation to cause a notification to occur when any arithmetic operation - returns an exceptional value as defined in LIA-1 clause 5. - H.3.1 Notification alternatives -1 LIA-1 requires at least the following two alternatives for handling of notifications: - setting indicators or trap-and-terminate. LIA-1 allows a third alternative: trap-and- - resume. -2 An implementation need only support a given notification alternative for the entire - program. An implementation may support the ability to switch between notification - alternatives during execution, but is not required to do so. An implementation can - provide separate selection for each kind of notification, but this is not required. -3 C allows an implementation to provide notification. C's SIGFPE (for traps) and - FE_INVALID, FE_DIVBYZERO, FE_OVERFLOW, FE_UNDERFLOW (for indicators) - can provide LIA-1 notification. -4 C's signal handlers are compatible with LIA-1. Default handling of SIGFPE can - provide trap-and-terminate behavior, except for those LIA-1 operations implemented by - math library function calls. User-provided signal handlers for SIGFPE allow for trap- - and-resume behavior with the same constraint. - H.3.1.1 Indicators -1 C's status flags are compatible with the LIA-1 indicators. -2 The following mapping is for floating-point types: - undefined FE_INVALID, FE_DIVBYZERO - floating_overflow FE_OVERFLOW - underflow FE_UNDERFLOW -3 The floating-point indicator interrogation and manipulation operations are: - set_indicators feraiseexcept(i) - clear_indicators feclearexcept(i) - test_indicators fetestexcept(i) - current_indicators fetestexcept(FE_ALL_EXCEPT) - where i is an expression of type int representing a subset of the LIA-1 indicators. -4 C allows an implementation to provide the following LIA-1 required behavior: at - program termination if any indicator is set the implementation shall send an unambiguous -[page 545] - - and ''hard to ignore'' message (see LIA-1 subclause 6.1.2) -5 LIA-1 does not make the distinction between floating-point and integer for ''undefined''. - This documentation makes that distinction because covers only the floating- - point indicators. - H.3.1.2 Traps -1 C is compatible with LIA-1's trap requirements for arithmetic operations, but not for - math library functions (which are not permitted to invoke a user's signal handler for - SIGFPE). An implementation can provide an alternative of notification through - termination with a ''hard-to-ignore'' message (see LIA-1 subclause 6.1.3). -2 LIA-1 does not require that traps be precise. -3 C does require that SIGFPE be the signal corresponding to arithmetic exceptions, if there - is any signal raised for them. -4 C supports signal handlers for SIGFPE and allows trapping of arithmetic exceptions. - When arithmetic exceptions do trap, C's signal-handler mechanism allows trap-and- - terminate (either default implementation behavior or user replacement for it) or trap-and- - resume, at the programmer's option. - - - - -[page 546] - - Annex I - (informative) - Common warnings -1 An implementation may generate warnings in many situations, none of which are - specified as part of this International Standard. The following are a few of the more - common situations. -2 -- A new struct or union type appears in a function prototype (6.2.1, 6.7.2.3). - -- A block with initialization of an object that has automatic storage duration is jumped - into (6.2.4). - -- An implicit narrowing conversion is encountered, such as the assignment of a long - int or a double to an int, or a pointer to void to a pointer to any type other than - a character type (6.3). - -- A hexadecimal floating constant cannot be represented exactly in its evaluation format - (6.4.4.2). - -- An integer character constant includes more than one character or a wide character - constant includes more than one multibyte character (6.4.4.4). - -- The characters /* are found in a comment (6.4.7). - -- An ''unordered'' binary operator (not comma, &&, or ||) contains a side effect to an - lvalue in one operand, and a side effect to, or an access to the value of, the identical - lvalue in the other operand (6.5). - -- A function is called but no prototype has been supplied (6.5.2.2). - -- The arguments in a function call do not agree in number and type with those of the - parameters in a function definition that is not a prototype (6.5.2.2). - -- An object is defined but not used (6.7). - -- A value is given to an object of an enumerated type other than by assignment of an - enumeration constant that is a member of that type, or an enumeration object that has - the same type, or the value of a function that returns the same enumerated type - (6.7.2.2). - -- An aggregate has a partly bracketed initialization (6.7.8). - -- A statement cannot be reached (6.8). - -- A statement with no apparent effect is encountered (6.8). - -- A constant expression is used as the controlling expression of a selection statement - (6.8.4). -[page 547] - --- An incorrectly formed preprocessing group is encountered while skipping a - preprocessing group (6.10.1). --- An unrecognized #pragma directive is encountered (6.10.6). - - - - -[page 548] - - Annex J - (informative) - Portability issues -1 This annex collects some information about portability that appears in this International - Standard. - J.1 Unspecified behavior -1 The following are unspecified: - -- The manner and timing of static initialization (5.1.2). - -- The termination status returned to the hosted environment if the return type of main - is not compatible with int (5.1.2.2.3). - -- The behavior of the display device if a printing character is written when the active - position is at the final position of a line (5.2.2). - -- The behavior of the display device if a backspace character is written when the active - position is at the initial position of a line (5.2.2). - -- The behavior of the display device if a horizontal tab character is written when the - active position is at or past the last defined horizontal tabulation position (5.2.2). - -- The behavior of the display device if a vertical tab character is written when the active - position is at or past the last defined vertical tabulation position (5.2.2). - -- How an extended source character that does not correspond to a universal character - name counts toward the significant initial characters in an external identifier (5.2.4.1). - -- Many aspects of the representations of types (6.2.6). - -- The value of padding bytes when storing values in structures or unions (6.2.6.1). - -- The values of bytes that correspond to union members other than the one last stored - into (6.2.6.1). - -- The representation used when storing a value in an object that has more than one - object representation for that value (6.2.6.1). - -- The values of any padding bits in integer representations (6.2.6.2). - -- Whether certain operators can generate negative zeros and whether a negative zero - becomes a normal zero when stored in an object (6.2.6.2). - -- Whether two string literals result in distinct arrays (6.4.5). - -- The order in which subexpressions are evaluated and the order in which side effects - take place, except as specified for the function-call (), &&, ||, ? :, and comma -[page 549] - - operators (6.5). --- The order in which the function designator, arguments, and subexpressions within the - arguments are evaluated in a function call (6.5.2.2). --- The order of side effects among compound literal initialization list expressions - (6.5.2.5). --- The order in which the operands of an assignment operator are evaluated (6.5.16). --- The alignment of the addressable storage unit allocated to hold a bit-field (6.7.2.1). --- Whether a call to an inline function uses the inline definition or the external definition - of the function (6.7.4). --- Whether or not a size expression is evaluated when it is part of the operand of a - sizeof operator and changing the value of the size expression would not affect the - result of the operator (6.7.6.2). --- The order in which any side effects occur among the initialization list expressions in - an initializer (6.7.9). --- The layout of storage for function parameters (6.9.1). --- When a fully expanded macro replacement list contains a function-like macro name - as its last preprocessing token and the next preprocessing token from the source file is - a (, and the fully expanded replacement of that macro ends with the name of the first - macro and the next preprocessing token from the source file is again a (, whether that - is considered a nested replacement (6.10.3). --- The order in which # and ## operations are evaluated during macro substitution - (6.10.3.2, 6.10.3.3). --- The state of the floating-point status flags when execution passes from a part of the - program translated with FENV_ACCESS ''off'' to a part translated with - FENV_ACCESS ''on'' (7.6.1). --- The order in which feraiseexcept raises floating-point exceptions, except as - stated in F.8.6 (7.6.2.3). --- Whether math_errhandling is a macro or an identifier with external linkage - (7.12). --- The results of the frexp functions when the specified value is not a floating-point - number (7.12.6.4). --- The numeric result of the ilogb functions when the correct value is outside the - range of the return type (7.12.6.5, F.10.3.5). --- The result of rounding when the value is out of range (7.12.9.5, 7.12.9.7, F.10.6.5). - - -[page 550] - --- The value stored by the remquo functions in the object pointed to by quo when y is - zero (7.12.10.3). --- Whether a comparison macro argument that is represented in a format wider than its - semantic type is converted to the semantic type (7.12.14). --- Whether setjmp is a macro or an identifier with external linkage (7.13). --- Whether va_copy and va_end are macros or identifiers with external linkage - (7.16.1). --- The hexadecimal digit before the decimal point when a non-normalized floating-point - number is printed with an a or A conversion specifier (7.21.6.1, 7.28.2.1). --- The value of the file position indicator after a successful call to the ungetc function - for a text stream, or the ungetwc function for any stream, until all pushed-back - characters are read or discarded (7.21.7.10, 7.28.3.10). --- The details of the value stored by the fgetpos function (7.21.9.1). --- The details of the value returned by the ftell function for a text stream (7.21.9.4). --- Whether the strtod, strtof, strtold, wcstod, wcstof, and wcstold - functions convert a minus-signed sequence to a negative number directly or by - negating the value resulting from converting the corresponding unsigned sequence - (7.22.1.3, 7.28.4.1.1). --- The order and contiguity of storage allocated by successive calls to the calloc, - malloc, and realloc functions (7.22.3). --- The amount of storage allocated by a successful call to the calloc, malloc, or - realloc function when 0 bytes was requested (7.22.3). --- Which of two elements that compare as equal is matched by the bsearch function - (7.22.5.1). --- The order of two elements that compare as equal in an array sorted by the qsort - function (7.22.5.2). --- The encoding of the calendar time returned by the time function (7.26.2.4). --- The characters stored by the strftime or wcsftime function if any of the time - values being converted is outside the normal range (7.26.3.5, 7.28.5.1). --- The conversion state after an encoding error occurs (7.28.6.3.2, 7.28.6.3.3, 7.28.6.4.1, - 7.28.6.4.2, --- The resulting value when the ''invalid'' floating-point exception is raised during - IEC 60559 floating to integer conversion (F.4). - - - -[page 551] - - -- Whether conversion of non-integer IEC 60559 floating values to integer raises the - ''inexact'' floating-point exception (F.4). - -- Whether or when library functions in raise the ''inexact'' floating-point - exception in an IEC 60559 conformant implementation (F.10). - -- Whether or when library functions in raise an undeserved ''underflow'' - floating-point exception in an IEC 60559 conformant implementation (F.10). - -- The exponent value stored by frexp for a NaN or infinity (F.10.3.4). - -- The numeric result returned by the lrint, llrint, lround, and llround - functions if the rounded value is outside the range of the return type (F.10.6.5, - F.10.6.7). - -- The sign of one part of the complex result of several math functions for certain - exceptional values in IEC 60559 compatible implementations (G.6.1.1, G.6.2.2, - G.6.2.3, G.6.2.4, G.6.2.5, G.6.2.6, G.6.3.1, G.6.4.2). - J.2 Undefined behavior -1 The behavior is undefined in the following circumstances: - -- A ''shall'' or ''shall not'' requirement that appears outside of a constraint is violated - (clause 4). - -- A nonempty source file does not end in a new-line character which is not immediately - preceded by a backslash character or ends in a partial preprocessing token or - comment (5.1.1.2). - -- Token concatenation produces a character sequence matching the syntax of a - universal character name (5.1.1.2). - -- A program in a hosted environment does not define a function named main using one - of the specified forms (5.1.2.2.1). - -- The execution of a program contains a data race (5.1.2.4). - -- A character not in the basic source character set is encountered in a source file, except - in an identifier, a character constant, a string literal, a header name, a comment, or a - preprocessing token that is never converted to a token (5.2.1). - -- An identifier, comment, string literal, character constant, or header name contains an - invalid multibyte character or does not begin and end in the initial shift state (5.2.1.2). - -- The same identifier has both internal and external linkage in the same translation unit - (6.2.2). - -- An object is referred to outside of its lifetime (6.2.4). - - - -[page 552] - --- The value of a pointer to an object whose lifetime has ended is used (6.2.4). --- The value of an object with automatic storage duration is used while it is - indeterminate (6.2.4, 6.7.9, 6.8). --- A trap representation is read by an lvalue expression that does not have character type - (6.2.6.1). --- A trap representation is produced by a side effect that modifies any part of the object - using an lvalue expression that does not have character type (6.2.6.1). --- The operands to certain operators are such that they could produce a negative zero - result, but the implementation does not support negative zeros (6.2.6.2). --- Two declarations of the same object or function specify types that are not compatible - (6.2.7). --- A program requires the formation of a composite type from a variable length array - type whose size is specified by an expression that is not evaluated (6.2.7). --- Conversion to or from an integer type produces a value outside the range that can be - represented (6.3.1.4). --- Demotion of one real floating type to another produces a value outside the range that - can be represented (6.3.1.5). --- An lvalue does not designate an object when evaluated (6.3.2.1). --- A non-array lvalue with an incomplete type is used in a context that requires the value - of the designated object (6.3.2.1). --- An lvalue designating an object of automatic storage duration that could have been - declared with the register storage class is used in a context that requires the value - of the designated object, but the object is uninitialized. (6.3.2.1). --- An lvalue having array type is converted to a pointer to the initial element of the - array, and the array object has register storage class (6.3.2.1). --- An attempt is made to use the value of a void expression, or an implicit or explicit - conversion (except to void) is applied to a void expression (6.3.2.2). --- Conversion of a pointer to an integer type produces a value outside the range that can - be represented (6.3.2.3). --- Conversion between two pointer types produces a result that is incorrectly aligned - (6.3.2.3). --- A pointer is used to call a function whose type is not compatible with the referenced - type (6.3.2.3). - - - -[page 553] - --- An unmatched ' or " character is encountered on a logical source line during - tokenization (6.4). --- A reserved keyword token is used in translation phase 7 or 8 for some purpose other - than as a keyword (6.4.1). --- A universal character name in an identifier does not designate a character whose - encoding falls into one of the specified ranges (6.4.2.1). --- The initial character of an identifier is a universal character name designating a digit - (6.4.2.1). --- Two identifiers differ only in nonsignificant characters (6.4.2.1). --- The identifier __func__ is explicitly declared (6.4.2.2). --- The program attempts to modify a string literal (6.4.5). --- The characters ', \, ", //, or /* occur in the sequence between the < and > - delimiters, or the characters ', \, //, or /* occur in the sequence between the " - delimiters, in a header name preprocessing token (6.4.7). --- A side effect on a scalar object is unsequenced relative to either a different side effect - on the same scalar object or a value computation using the value of the same scalar - object (6.5). --- An exceptional condition occurs during the evaluation of an expression (6.5). --- An object has its stored value accessed other than by an lvalue of an allowable type - (6.5). --- For a call to a function without a function prototype in scope, the number of - arguments does not equal the number of parameters (6.5.2.2). --- For call to a function without a function prototype in scope where the function is - defined with a function prototype, either the prototype ends with an ellipsis or the - types of the arguments after promotion are not compatible with the types of the - parameters (6.5.2.2). --- For a call to a function without a function prototype in scope where the function is not - defined with a function prototype, the types of the arguments after promotion are not - compatible with those of the parameters after promotion (with certain exceptions) - (6.5.2.2). --- A function is defined with a type that is not compatible with the type (of the - expression) pointed to by the expression that denotes the called function (6.5.2.2). --- A member of an _Atomic-qualified structure or union is accessed (6.5.2.3). --- The operand of the unary * operator has an invalid value (6.5.3.2). - - -[page 554] - --- A pointer is converted to other than an integer or pointer type (6.5.4). --- The value of the second operand of the / or % operator is zero (6.5.5). --- Addition or subtraction of a pointer into, or just beyond, an array object and an - integer type produces a result that does not point into, or just beyond, the same array - object (6.5.6). --- Addition or subtraction of a pointer into, or just beyond, an array object and an - integer type produces a result that points just beyond the array object and is used as - the operand of a unary * operator that is evaluated (6.5.6). --- Pointers that do not point into, or just beyond, the same array object are subtracted - (6.5.6). --- An array subscript is out of range, even if an object is apparently accessible with the - given subscript (as in the lvalue expression a[1][7] given the declaration int - a[4][5]) (6.5.6). --- The result of subtracting two pointers is not representable in an object of type - ptrdiff_t (6.5.6). --- An expression is shifted by a negative number or by an amount greater than or equal - to the width of the promoted expression (6.5.7). --- An expression having signed promoted type is left-shifted and either the value of the - expression is negative or the result of shifting would be not be representable in the - promoted type (6.5.7). --- Pointers that do not point to the same aggregate or union (nor just beyond the same - array object) are compared using relational operators (6.5.8). --- An object is assigned to an inexactly overlapping object or to an exactly overlapping - object with incompatible type (6.5.16.1). --- An expression that is required to be an integer constant expression does not have an - integer type; has operands that are not integer constants, enumeration constants, - character constants, sizeof expressions whose results are integer constants, or - immediately-cast floating constants; or contains casts (outside operands to sizeof - operators) other than conversions of arithmetic types to integer types (6.6). --- A constant expression in an initializer is not, or does not evaluate to, one of the - following: an arithmetic constant expression, a null pointer constant, an address - constant, or an address constant for a complete object type plus or minus an integer - constant expression (6.6). --- An arithmetic constant expression does not have arithmetic type; has operands that - are not integer constants, floating constants, enumeration constants, character - constants, or sizeof expressions; or contains casts (outside operands to sizeof - -[page 555] - - operators) other than conversions of arithmetic types to arithmetic types (6.6). --- The value of an object is accessed by an array-subscript [], member-access . or ->, - address &, or indirection * operator or a pointer cast in creating an address constant - (6.6). --- An identifier for an object is declared with no linkage and the type of the object is - incomplete after its declarator, or after its init-declarator if it has an initializer (6.7). --- A function is declared at block scope with an explicit storage-class specifier other - than extern (6.7.1). --- A structure or union is defined as containing no named members, no anonymous - structures, and no anonymous unions (6.7.2.1). --- An attempt is made to access, or generate a pointer to just past, a flexible array - member of a structure when the referenced object provides no elements for that array - (6.7.2.1). --- When the complete type is needed, an incomplete structure or union type is not - completed in the same scope by another declaration of the tag that defines the content - (6.7.2.3). --- An attempt is made to modify an object defined with a const-qualified type through - use of an lvalue with non-const-qualified type (6.7.3). --- An attempt is made to refer to an object defined with a volatile-qualified type through - use of an lvalue with non-volatile-qualified type (6.7.3). --- An attempt is made to refer to an object defined with an _Atomic-qualified type - through use of an lvalue with non-_Atomic-qualified type (6.7.3). --- The specification of a function type includes any type qualifiers (6.7.3). --- Two qualified types that are required to be compatible do not have the identically - qualified version of a compatible type (6.7.3). --- An object which has been modified is accessed through a restrict-qualified pointer to - a const-qualified type, or through a restrict-qualified pointer and another pointer that - are not both based on the same object (6.7.3.1). --- A restrict-qualified pointer is assigned a value based on another restricted pointer - whose associated block neither began execution before the block associated with this - pointer, nor ended before the assignment (6.7.3.1). --- A function with external linkage is declared with an inline function specifier, but is - not also defined in the same translation unit (6.7.4). --- A function declared with a _Noreturn function specifier returns to its caller (6.7.4). - - -[page 556] - --- The definition of an object has an alignment specifier and another declaration of that - object has a different alignment specifier (6.7.5). --- Declarations of an object in different translation units have different alignment - specifiers (6.7.5). --- Two pointer types that are required to be compatible are not identically qualified, or - are not pointers to compatible types (6.7.6.1). --- The size expression in an array declaration is not a constant expression and evaluates - at program execution time to a nonpositive value (6.7.6.2). --- In a context requiring two array types to be compatible, they do not have compatible - element types, or their size specifiers evaluate to unequal values (6.7.6.2). --- A declaration of an array parameter includes the keyword static within the [ and - ] and the corresponding argument does not provide access to the first element of an - array with at least the specified number of elements (6.7.6.3). --- A storage-class specifier or type qualifier modifies the keyword void as a function - parameter type list (6.7.6.3). --- In a context requiring two function types to be compatible, they do not have - compatible return types, or their parameters disagree in use of the ellipsis terminator - or the number and type of parameters (after default argument promotion, when there - is no parameter type list or when one type is specified by a function definition with an - identifier list) (6.7.6.3). --- The value of an unnamed member of a structure or union is used (6.7.9). --- The initializer for a scalar is neither a single expression nor a single expression - enclosed in braces (6.7.9). --- The initializer for a structure or union object that has automatic storage duration is - neither an initializer list nor a single expression that has compatible structure or union - type (6.7.9). --- The initializer for an aggregate or union, other than an array initialized by a string - literal, is not a brace-enclosed list of initializers for its elements or members (6.7.9). --- An identifier with external linkage is used, but in the program there does not exist - exactly one external definition for the identifier, or the identifier is not used and there - exist multiple external definitions for the identifier (6.9). --- A function definition includes an identifier list, but the types of the parameters are not - declared in a following declaration list (6.9.1). --- An adjusted parameter type in a function definition is not a complete object type - (6.9.1). - -[page 557] - --- A function that accepts a variable number of arguments is defined without a - parameter type list that ends with the ellipsis notation (6.9.1). --- The } that terminates a function is reached, and the value of the function call is used - by the caller (6.9.1). --- An identifier for an object with internal linkage and an incomplete type is declared - with a tentative definition (6.9.2). --- The token defined is generated during the expansion of a #if or #elif - preprocessing directive, or the use of the defined unary operator does not match - one of the two specified forms prior to macro replacement (6.10.1). --- The #include preprocessing directive that results after expansion does not match - one of the two header name forms (6.10.2). --- The character sequence in an #include preprocessing directive does not start with a - letter (6.10.2). --- There are sequences of preprocessing tokens within the list of macro arguments that - would otherwise act as preprocessing directives (6.10.3). --- The result of the preprocessing operator # is not a valid character string literal - (6.10.3.2). --- The result of the preprocessing operator ## is not a valid preprocessing token - (6.10.3.3). --- The #line preprocessing directive that results after expansion does not match one of - the two well-defined forms, or its digit sequence specifies zero or a number greater - than 2147483647 (6.10.4). --- A non-STDC #pragma preprocessing directive that is documented as causing - translation failure or some other form of undefined behavior is encountered (6.10.6). --- A #pragma STDC preprocessing directive does not match one of the well-defined - forms (6.10.6). --- The name of a predefined macro, or the identifier defined, is the subject of a - #define or #undef preprocessing directive (6.10.8). --- An attempt is made to copy an object to an overlapping object by use of a library - function, other than as explicitly allowed (e.g., memmove) (clause 7). --- A file with the same name as one of the standard headers, not provided as part of the - implementation, is placed in any of the standard places that are searched for included - source files (7.1.2). --- A header is included within an external declaration or definition (7.1.2). - - -[page 558] - --- A function, object, type, or macro that is specified as being declared or defined by - some standard header is used before any header that declares or defines it is included - (7.1.2). --- A standard header is included while a macro is defined with the same name as a - keyword (7.1.2). --- The program attempts to declare a library function itself, rather than via a standard - header, but the declaration does not have external linkage (7.1.2). --- The program declares or defines a reserved identifier, other than as allowed by 7.1.4 - (7.1.3). --- The program removes the definition of a macro whose name begins with an - underscore and either an uppercase letter or another underscore (7.1.3). --- An argument to a library function has an invalid value or a type not expected by a - function with variable number of arguments (7.1.4). --- The pointer passed to a library function array parameter does not have a value such - that all address computations and object accesses are valid (7.1.4). --- The macro definition of assert is suppressed in order to access an actual function - (7.2). --- The argument to the assert macro does not have a scalar type (7.2). --- The CX_LIMITED_RANGE, FENV_ACCESS, or FP_CONTRACT pragma is used in - any context other than outside all external declarations or preceding all explicit - declarations and statements inside a compound statement (7.3.4, 7.6.1, 7.12.2). --- The value of an argument to a character handling function is neither equal to the value - of EOF nor representable as an unsigned char (7.4). --- A macro definition of errno is suppressed in order to access an actual object, or the - program defines an identifier with the name errno (7.5). --- Part of the program tests floating-point status flags, sets floating-point control modes, - or runs under non-default mode settings, but was translated with the state for the - FENV_ACCESS pragma ''off'' (7.6.1). --- The exception-mask argument for one of the functions that provide access to the - floating-point status flags has a nonzero value not obtained by bitwise OR of the - floating-point exception macros (7.6.2). --- The fesetexceptflag function is used to set floating-point status flags that were - not specified in the call to the fegetexceptflag function that provided the value - of the corresponding fexcept_t object (7.6.2.4). - - - -[page 559] - --- The argument to fesetenv or feupdateenv is neither an object set by a call to - fegetenv or feholdexcept, nor is it an environment macro (7.6.4.3, 7.6.4.4). --- The value of the result of an integer arithmetic or conversion function cannot be - represented (7.8.2.1, 7.8.2.2, 7.8.2.3, 7.8.2.4, 7.22.6.1, 7.22.6.2, 7.22.1). --- The program modifies the string pointed to by the value returned by the setlocale - function (7.11.1.1). --- The program modifies the structure pointed to by the value returned by the - localeconv function (7.11.2.1). --- A macro definition of math_errhandling is suppressed or the program defines - an identifier with the name math_errhandling (7.12). --- An argument to a floating-point classification or comparison macro is not of real - floating type (7.12.3, 7.12.14). --- A macro definition of setjmp is suppressed in order to access an actual function, or - the program defines an external identifier with the name setjmp (7.13). --- An invocation of the setjmp macro occurs other than in an allowed context - (7.13.2.1). --- The longjmp function is invoked to restore a nonexistent environment (7.13.2.1). --- After a longjmp, there is an attempt to access the value of an object of automatic - storage duration that does not have volatile-qualified type, local to the function - containing the invocation of the corresponding setjmp macro, that was changed - between the setjmp invocation and longjmp call (7.13.2.1). --- The program specifies an invalid pointer to a signal handler function (7.14.1.1). --- A signal handler returns when the signal corresponded to a computational exception - (7.14.1.1). --- A signal occurs as the result of calling the abort or raise function, and the signal - handler calls the raise function (7.14.1.1). --- A signal occurs other than as the result of calling the abort or raise function, and - the signal handler refers to an object with static storage duration other than by - assigning a value to an object declared as volatile sig_atomic_t, or calls any - function in the standard library other than the abort function, the _Exit function, - the quick_exit function, or the signal function (for the same signal number) - (7.14.1.1). --- The value of errno is referred to after a signal occurred other than as the result of - calling the abort or raise function and the corresponding signal handler obtained - a SIG_ERR return from a call to the signal function (7.14.1.1). - -[page 560] - --- A signal is generated by an asynchronous signal handler (7.14.1.1). --- A function with a variable number of arguments attempts to access its varying - arguments other than through a properly declared and initialized va_list object, or - before the va_start macro is invoked (7.16, 7.16.1.1, 7.16.1.4). --- The macro va_arg is invoked using the parameter ap that was passed to a function - that invoked the macro va_arg with the same parameter (7.16). --- A macro definition of va_start, va_arg, va_copy, or va_end is suppressed in - order to access an actual function, or the program defines an external identifier with - the name va_copy or va_end (7.16.1). --- The va_start or va_copy macro is invoked without a corresponding invocation - of the va_end macro in the same function, or vice versa (7.16.1, 7.16.1.2, 7.16.1.3, - 7.16.1.4). --- The type parameter to the va_arg macro is not such that a pointer to an object of - that type can be obtained simply by postfixing a * (7.16.1.1). --- The va_arg macro is invoked when there is no actual next argument, or with a - specified type that is not compatible with the promoted type of the actual next - argument, with certain exceptions (7.16.1.1). --- The va_copy or va_start macro is called to initialize a va_list that was - previously initialized by either macro without an intervening invocation of the - va_end macro for the same va_list (7.16.1.2, 7.16.1.4). --- The parameter parmN of a va_start macro is declared with the register - storage class, with a function or array type, or with a type that is not compatible with - the type that results after application of the default argument promotions (7.16.1.4). --- The member designator parameter of an offsetof macro is an invalid right - operand of the . operator for the type parameter, or designates a bit-field (7.19). --- The argument in an instance of one of the integer-constant macros is not a decimal, - octal, or hexadecimal constant, or it has a value that exceeds the limits for the - corresponding type (7.20.4). --- A byte input/output function is applied to a wide-oriented stream, or a wide character - input/output function is applied to a byte-oriented stream (7.21.2). --- Use is made of any portion of a file beyond the most recent wide character written to - a wide-oriented stream (7.21.2). --- The value of a pointer to a FILE object is used after the associated file is closed - (7.21.3). --- The stream for the fflush function points to an input stream or to an update stream - in which the most recent operation was input (7.21.5.2). -[page 561] - --- The string pointed to by the mode argument in a call to the fopen function does not - exactly match one of the specified character sequences (7.21.5.3). --- An output operation on an update stream is followed by an input operation without an - intervening call to the fflush function or a file positioning function, or an input - operation on an update stream is followed by an output operation with an intervening - call to a file positioning function (7.21.5.3). --- An attempt is made to use the contents of the array that was supplied in a call to the - setvbuf function (7.21.5.6). --- There are insufficient arguments for the format in a call to one of the formatted - input/output functions, or an argument does not have an appropriate type (7.21.6.1, - 7.21.6.2, 7.28.2.1, 7.28.2.2). --- The format in a call to one of the formatted input/output functions or to the - strftime or wcsftime function is not a valid multibyte character sequence that - begins and ends in its initial shift state (7.21.6.1, 7.21.6.2, 7.26.3.5, 7.28.2.1, 7.28.2.2, - 7.28.5.1). --- In a call to one of the formatted output functions, a precision appears with a - conversion specifier other than those described (7.21.6.1, 7.28.2.1). --- A conversion specification for a formatted output function uses an asterisk to denote - an argument-supplied field width or precision, but the corresponding argument is not - provided (7.21.6.1, 7.28.2.1). --- A conversion specification for a formatted output function uses a # or 0 flag with a - conversion specifier other than those described (7.21.6.1, 7.28.2.1). --- A conversion specification for one of the formatted input/output functions uses a - length modifier with a conversion specifier other than those described (7.21.6.1, - 7.21.6.2, 7.28.2.1, 7.28.2.2). --- An s conversion specifier is encountered by one of the formatted output functions, - and the argument is missing the null terminator (unless a precision is specified that - does not require null termination) (7.21.6.1, 7.28.2.1). --- An n conversion specification for one of the formatted input/output functions includes - any flags, an assignment-suppressing character, a field width, or a precision (7.21.6.1, - 7.21.6.2, 7.28.2.1, 7.28.2.2). --- A % conversion specifier is encountered by one of the formatted input/output - functions, but the complete conversion specification is not exactly %% (7.21.6.1, - 7.21.6.2, 7.28.2.1, 7.28.2.2). --- An invalid conversion specification is found in the format for one of the formatted - input/output functions, or the strftime or wcsftime function (7.21.6.1, 7.21.6.2, - -[page 562] - - 7.26.3.5, 7.28.2.1, 7.28.2.2, 7.28.5.1). --- The number of characters transmitted by a formatted output function is greater than - INT_MAX (7.21.6.1, 7.21.6.3, 7.21.6.8, 7.21.6.10). --- The result of a conversion by one of the formatted input functions cannot be - represented in the corresponding object, or the receiving object does not have an - appropriate type (7.21.6.2, 7.28.2.2). --- A c, s, or [ conversion specifier is encountered by one of the formatted input - functions, and the array pointed to by the corresponding argument is not large enough - to accept the input sequence (and a null terminator if the conversion specifier is s or - [) (7.21.6.2, 7.28.2.2). --- A c, s, or [ conversion specifier with an l qualifier is encountered by one of the - formatted input functions, but the input is not a valid multibyte character sequence - that begins in the initial shift state (7.21.6.2, 7.28.2.2). --- The input item for a %p conversion by one of the formatted input functions is not a - value converted earlier during the same program execution (7.21.6.2, 7.28.2.2). --- The vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf, - vsscanf, vfwprintf, vfwscanf, vswprintf, vswscanf, vwprintf, or - vwscanf function is called with an improperly initialized va_list argument, or - the argument is used (other than in an invocation of va_end) after the function - returns (7.21.6.8, 7.21.6.9, 7.21.6.10, 7.21.6.11, 7.21.6.12, 7.21.6.13, 7.21.6.14, - 7.28.2.5, 7.28.2.6, 7.28.2.7, 7.28.2.8, 7.28.2.9, 7.28.2.10). --- The contents of the array supplied in a call to the fgets or fgetws function are - used after a read error occurred (7.21.7.2, 7.28.3.2). --- The file position indicator for a binary stream is used after a call to the ungetc - function where its value was zero before the call (7.21.7.10). --- The file position indicator for a stream is used after an error occurred during a call to - the fread or fwrite function (7.21.8.1, 7.21.8.2). --- A partial element read by a call to the fread function is used (7.21.8.1). --- The fseek function is called for a text stream with a nonzero offset and either the - offset was not returned by a previous successful call to the ftell function on a - stream associated with the same file or whence is not SEEK_SET (7.21.9.2). --- The fsetpos function is called to set a position that was not returned by a previous - successful call to the fgetpos function on a stream associated with the same file - (7.21.9.3). --- A non-null pointer returned by a call to the calloc, malloc, or realloc function - with a zero requested size is used to access an object (7.22.3). - -[page 563] - --- The value of a pointer that refers to space deallocated by a call to the free or - realloc function is used (7.22.3). --- The alignment requested of the aligned_alloc function is not valid or not - supported by the implementation, or the size requested is not an integral multiple of - the alignment (7.22.3.1). --- The pointer argument to the free or realloc function does not match a pointer - earlier returned by a memory management function, or the space has been deallocated - by a call to free or realloc (7.22.3.3, 7.22.3.5). --- The value of the object allocated by the malloc function is used (7.22.3.4). --- The value of any bytes in a new object allocated by the realloc function beyond - the size of the old object are used (7.22.3.5). --- The program calls the exit or quick_exit function more than once, or calls both - functions (7.22.4.4, 7.22.4.7). --- During the call to a function registered with the atexit or at_quick_exit - function, a call is made to the longjmp function that would terminate the call to the - registered function (7.22.4.4, 7.22.4.7). --- The string set up by the getenv or strerror function is modified by the program - (7.22.4.6, 7.23.6.2). --- A command is executed through the system function in a way that is documented as - causing termination or some other form of undefined behavior (7.22.4.8). --- A searching or sorting utility function is called with an invalid pointer argument, even - if the number of elements is zero (7.22.5). --- The comparison function called by a searching or sorting utility function alters the - contents of the array being searched or sorted, or returns ordering values - inconsistently (7.22.5). --- The array being searched by the bsearch function does not have its elements in - proper order (7.22.5.1). --- The current conversion state is used by a multibyte/wide character conversion - function after changing the LC_CTYPE category (7.22.7). --- A string or wide string utility function is instructed to access an array beyond the end - of an object (7.23.1, 7.28.4). --- A string or wide string utility function is called with an invalid pointer argument, even - if the length is zero (7.23.1, 7.28.4). --- The contents of the destination array are used after a call to the strxfrm, - strftime, wcsxfrm, or wcsftime function in which the specified length was - -[page 564] - - too small to hold the entire null-terminated result (7.23.4.5, 7.26.3.5, 7.28.4.4.4, - 7.28.5.1). --- The first argument in the very first call to the strtok or wcstok is a null pointer - (7.23.5.8, 7.28.4.5.7). --- The type of an argument to a type-generic macro is not compatible with the type of - the corresponding parameter of the selected function (7.24). --- A complex argument is supplied for a generic parameter of a type-generic macro that - has no corresponding complex function (7.24). --- At least one field of the broken-down time passed to asctime contains a value - outside its normal range, or the calculated year exceeds four digits or is less than the - year 1000 (7.26.3.1). --- The argument corresponding to an s specifier without an l qualifier in a call to the - fwprintf function does not point to a valid multibyte character sequence that - begins in the initial shift state (7.28.2.11). --- In a call to the wcstok function, the object pointed to by ptr does not have the - value stored by the previous call for the same wide string (7.28.4.5.7). --- An mbstate_t object is used inappropriately (7.28.6). --- The value of an argument of type wint_t to a wide character classification or case - mapping function is neither equal to the value of WEOF nor representable as a - wchar_t (7.29.1). --- The iswctype function is called using a different LC_CTYPE category from the - one in effect for the call to the wctype function that returned the description - (7.29.2.2.1). --- The towctrans function is called using a different LC_CTYPE category from the - one in effect for the call to the wctrans function that returned the description - (7.29.3.2.1). - - - - -[page 565] - - J.3 Implementation-defined behavior -1 A conforming implementation is required to document its choice of behavior in each of - the areas listed in this subclause. The following are implementation-defined: - J.3.1 Translation -1 -- How a diagnostic is identified (3.10, 5.1.1.3). - -- Whether each nonempty sequence of white-space characters other than new-line is - retained or replaced by one space character in translation phase 3 (5.1.1.2). - J.3.2 Environment -1 -- The mapping between physical source file multibyte characters and the source - character set in translation phase 1 (5.1.1.2). - -- The name and type of the function called at program startup in a freestanding - environment (5.1.2.1). - -- The effect of program termination in a freestanding environment (5.1.2.1). - -- An alternative manner in which the main function may be defined (5.1.2.2.1). - -- The values given to the strings pointed to by the argv argument to main (5.1.2.2.1). - -- What constitutes an interactive device (5.1.2.3). - -- Whether a program can have more than one thread of execution in a freestanding - environment (5.1.2.4). - -- The set of signals, their semantics, and their default handling (7.14). - -- Signal values other than SIGFPE, SIGILL, and SIGSEGV that correspond to a - computational exception (7.14.1.1). - -- Signals for which the equivalent of signal(sig, SIG_IGN); is executed at - program startup (7.14.1.1). - -- The set of environment names and the method for altering the environment list used - by the getenv function (7.22.4.6). - -- The manner of execution of the string by the system function (7.22.4.8). - - - - -[page 566] - - J.3.3 Identifiers -1 -- Which additional multibyte characters may appear in identifiers and their - correspondence to universal character names (6.4.2). - -- The number of significant initial characters in an identifier (5.2.4.1, 6.4.2). - J.3.4 Characters -1 -- The number of bits in a byte (3.6). - -- The values of the members of the execution character set (5.2.1). - -- The unique value of the member of the execution character set produced for each of - the standard alphabetic escape sequences (5.2.2). - -- The value of a char object into which has been stored any character other than a - member of the basic execution character set (6.2.5). - -- Which of signed char or unsigned char has the same range, representation, - and behavior as ''plain'' char (6.2.5, 6.3.1.1). - -- The mapping of members of the source character set (in character constants and string - literals) to members of the execution character set (6.4.4.4, 5.1.1.2). - -- The value of an integer character constant containing more than one character or - containing a character or escape sequence that does not map to a single-byte - execution character (6.4.4.4). - -- The value of a wide character constant containing more than one multibyte character - or a single multibyte character that maps to multiple members of the extended - execution character set, or containing a multibyte character or escape sequence not - represented in the extended execution character set (6.4.4.4). - -- The current locale used to convert a wide character constant consisting of a single - multibyte character that maps to a member of the extended execution character set - into a corresponding wide character code (6.4.4.4). - -- Whether differently-prefixed wide string literal tokens can be concatenated and, if so, - the treatment of the resulting multibyte character sequence (6.4.5). - -- The current locale used to convert a wide string literal into corresponding wide - character codes (6.4.5). - -- The value of a string literal containing a multibyte character or escape sequence not - represented in the execution character set (6.4.5). - -- The encoding of any of wchar_t, char16_t, and char32_t where the - corresponding standard encoding macro (__STDC_ISO_10646__, - __STDC_UTF_16__, or __STDC_UTF_32__) is not defined (6.10.8.2). - -[page 567] - - J.3.5 Integers -1 -- Any extended integer types that exist in the implementation (6.2.5). - -- Whether signed integer types are represented using sign and magnitude, two's - complement, or ones' complement, and whether the extraordinary value is a trap - representation or an ordinary value (6.2.6.2). - -- The rank of any extended integer type relative to another extended integer type with - the same precision (6.3.1.1). - -- The result of, or the signal raised by, converting an integer to a signed integer type - when the value cannot be represented in an object of that type (6.3.1.3). - -- The results of some bitwise operations on signed integers (6.5). - J.3.6 Floating point -1 -- The accuracy of the floating-point operations and of the library functions in - and that return floating-point results (5.2.4.2.2). - -- The accuracy of the conversions between floating-point internal representations and - string representations performed by the library functions in , - , and (5.2.4.2.2). - -- The rounding behaviors characterized by non-standard values of FLT_ROUNDS - (5.2.4.2.2). - -- The evaluation methods characterized by non-standard negative values of - FLT_EVAL_METHOD (5.2.4.2.2). - -- The direction of rounding when an integer is converted to a floating-point number that - cannot exactly represent the original value (6.3.1.4). - -- The direction of rounding when a floating-point number is converted to a narrower - floating-point number (6.3.1.5). - -- How the nearest representable value or the larger or smaller representable value - immediately adjacent to the nearest representable value is chosen for certain floating - constants (6.4.4.2). - -- Whether and how floating expressions are contracted when not disallowed by the - FP_CONTRACT pragma (6.5). - -- The default state for the FENV_ACCESS pragma (7.6.1). - -- Additional floating-point exceptions, rounding modes, environments, and - classifications, and their macro names (7.6, 7.12). - -- The default state for the FP_CONTRACT pragma (7.12.2). - - -[page 568] - - J.3.7 Arrays and pointers -1 -- The result of converting a pointer to an integer or vice versa (6.3.2.3). - -- The size of the result of subtracting two pointers to elements of the same array - (6.5.6). - J.3.8 Hints -1 -- The extent to which suggestions made by using the register storage-class - specifier are effective (6.7.1). - -- The extent to which suggestions made by using the inline function specifier are - effective (6.7.4). - J.3.9 Structures, unions, enumerations, and bit-fields -1 -- Whether a ''plain'' int bit-field is treated as a signed int bit-field or as an - unsigned int bit-field (6.7.2, 6.7.2.1). - -- Allowable bit-field types other than _Bool, signed int, and unsigned int - (6.7.2.1). - -- Whether a bit-field can straddle a storage-unit boundary (6.7.2.1). - -- The order of allocation of bit-fields within a unit (6.7.2.1). - -- The alignment of non-bit-field members of structures (6.7.2.1). This should present - no problem unless binary data written by one implementation is read by another. - -- The integer type compatible with each enumerated type (6.7.2.2). - J.3.10 Qualifiers -1 -- What constitutes an access to an object that has volatile-qualified type (6.7.3). - J.3.11 Preprocessing directives -1 -- The locations within #pragma directives where header name preprocessing tokens - are recognized (6.4, 6.4.7). - -- How sequences in both forms of header names are mapped to headers or external - source file names (6.4.7). - -- Whether the value of a character constant in a constant expression that controls - conditional inclusion matches the value of the same character constant in the - execution character set (6.10.1). - -- Whether the value of a single-character character constant in a constant expression - that controls conditional inclusion may have a negative value (6.10.1). - -- The places that are searched for an included < > delimited header, and how the places - are specified or the header is identified (6.10.2). -[page 569] - - -- How the named source file is searched for in an included " " delimited header - (6.10.2). - -- The method by which preprocessing tokens (possibly resulting from macro - expansion) in a #include directive are combined into a header name (6.10.2). - -- The nesting limit for #include processing (6.10.2). - -- Whether the # operator inserts a \ character before the \ character that begins a - universal character name in a character constant or string literal (6.10.3.2). - -- The behavior on each recognized non-STDC #pragma directive (6.10.6). - -- The definitions for __DATE__ and __TIME__ when respectively, the date and - time of translation are not available (6.10.8.1). - J.3.12 Library functions -1 -- Any library facilities available to a freestanding program, other than the minimal set - required by clause 4 (5.1.2.1). - -- The format of the diagnostic printed by the assert macro (7.2.1.1). - -- The representation of the floating-point status flags stored by the - fegetexceptflag function (7.6.2.2). - -- Whether the feraiseexcept function raises the ''inexact'' floating-point - exception in addition to the ''overflow'' or ''underflow'' floating-point exception - (7.6.2.3). - -- Strings other than "C" and "" that may be passed as the second argument to the - setlocale function (7.11.1.1). - -- The types defined for float_t and double_t when the value of the - FLT_EVAL_METHOD macro is less than 0 (7.12). - -- Domain errors for the mathematics functions, other than those required by this - International Standard (7.12.1). - -- The values returned by the mathematics functions on domain errors or pole errors - (7.12.1). - -- The values returned by the mathematics functions on underflow range errors, whether - errno is set to the value of the macro ERANGE when the integer expression - math_errhandling & MATH_ERRNO is nonzero, and whether the ''underflow'' - floating-point exception is raised when the integer expression math_errhandling - & MATH_ERREXCEPT is nonzero. (7.12.1). - -- Whether a domain error occurs or zero is returned when an fmod function has a - second argument of zero (7.12.10.1). - -[page 570] - --- Whether a domain error occurs or zero is returned when a remainder function has - a second argument of zero (7.12.10.2). --- The base-2 logarithm of the modulus used by the remquo functions in reducing the - quotient (7.12.10.3). --- Whether a domain error occurs or zero is returned when a remquo function has a - second argument of zero (7.12.10.3). --- Whether the equivalent of signal(sig, SIG_DFL); is executed prior to the call - of a signal handler, and, if not, the blocking of signals that is performed (7.14.1.1). --- The null pointer constant to which the macro NULL expands (7.19). --- Whether the last line of a text stream requires a terminating new-line character - (7.21.2). --- Whether space characters that are written out to a text stream immediately before a - new-line character appear when read in (7.21.2). --- The number of null characters that may be appended to data written to a binary - stream (7.21.2). --- Whether the file position indicator of an append-mode stream is initially positioned at - the beginning or end of the file (7.21.3). --- Whether a write on a text stream causes the associated file to be truncated beyond that - point (7.21.3). --- The characteristics of file buffering (7.21.3). --- Whether a zero-length file actually exists (7.21.3). --- The rules for composing valid file names (7.21.3). --- Whether the same file can be simultaneously open multiple times (7.21.3). --- The nature and choice of encodings used for multibyte characters in files (7.21.3). --- The effect of the remove function on an open file (7.21.4.1). --- The effect if a file with the new name exists prior to a call to the rename function - (7.21.4.2). --- Whether an open temporary file is removed upon abnormal program termination - (7.21.4.3). --- Which changes of mode are permitted (if any), and under what circumstances - (7.21.5.4). --- The style used to print an infinity or NaN, and the meaning of any n-char or n-wchar - sequence printed for a NaN (7.21.6.1, 7.28.2.1). - -[page 571] - --- The output for %p conversion in the fprintf or fwprintf function (7.21.6.1, - 7.28.2.1). --- The interpretation of a - character that is neither the first nor the last character, nor - the second where a ^ character is the first, in the scanlist for %[ conversion in the - fscanf or fwscanf function (7.21.6.2, 7.28.2.1). --- The set of sequences matched by a %p conversion and the interpretation of the - corresponding input item in the fscanf or fwscanf function (7.21.6.2, 7.28.2.2). --- The value to which the macro errno is set by the fgetpos, fsetpos, or ftell - functions on failure (7.21.9.1, 7.21.9.3, 7.21.9.4). --- The meaning of any n-char or n-wchar sequence in a string representing a NaN that is - converted by the strtod, strtof, strtold, wcstod, wcstof, or wcstold - function (7.22.1.3, 7.28.4.1.1). --- Whether or not the strtod, strtof, strtold, wcstod, wcstof, or wcstold - function sets errno to ERANGE when underflow occurs (7.22.1.3, 7.28.4.1.1). --- Whether the calloc, malloc, and realloc functions return a null pointer or a - pointer to an allocated object when the size requested is zero (7.22.3). --- Whether open streams with unwritten buffered data are flushed, open streams are - closed, or temporary files are removed when the abort or _Exit function is called - (7.22.4.1, 7.22.4.5). --- The termination status returned to the host environment by the abort, exit, - _Exit, or quick_exit function (7.22.4.1, 7.22.4.4, 7.22.4.5, 7.22.4.7). --- The value returned by the system function when its argument is not a null pointer - (7.22.4.8). --- The local time zone and Daylight Saving Time (7.26.1). --- The range and precision of times representable in clock_t and time_t (7.26). --- The era for the clock function (7.26.2.1). --- The replacement string for the %Z specifier to the strftime, and wcsftime - functions in the "C" locale (7.26.3.5, 7.28.5.1). --- Whether the functions in honor the rounding direction mode in an - IEC 60559 conformant implementation, unless explicitly specified otherwise (F.10). - - - - -[page 572] - - J.3.13 Architecture -1 -- The values or expressions assigned to the macros specified in the headers - , , and (5.2.4.2, 7.20.2, 7.20.3). - -- The result of attempting to indirectly access an object with automatic or thread - storage duration from a thread other than the one with which it is associated (6.2.4). - -- The number, order, and encoding of bytes in any object (when not explicitly specified - in this International Standard) (6.2.6.1). - -- Whether any extended alignments are supported and the contexts in which they are - supported (6.2.8). - -- Valid alignment values other than those returned by an alignof expression for - fundamental types, if any (6.2.8). - -- The value of the result of the sizeof and alignof operators (6.5.3.4). - J.4 Locale-specific behavior -1 The following characteristics of a hosted environment are locale-specific and are required - to be documented by the implementation: - -- Additional members of the source and execution character sets beyond the basic - character set (5.2.1). - -- The presence, meaning, and representation of additional multibyte characters in the - execution character set beyond the basic character set (5.2.1.2). - -- The shift states used for the encoding of multibyte characters (5.2.1.2). - -- The direction of writing of successive printing characters (5.2.2). - -- The decimal-point character (7.1.1). - -- The set of printing characters (7.4, 7.29.2). - -- The set of control characters (7.4, 7.29.2). - -- The sets of characters tested for by the isalpha, isblank, islower, ispunct, - isspace, isupper, iswalpha, iswblank, iswlower, iswpunct, - iswspace, or iswupper functions (7.4.1.2, 7.4.1.3, 7.4.1.7, 7.4.1.9, 7.4.1.10, - 7.4.1.11, 7.29.2.1.2, 7.29.2.1.3, 7.29.2.1.7, 7.29.2.1.9, 7.29.2.1.10, 7.29.2.1.11). - -- The native environment (7.11.1.1). - -- Additional subject sequences accepted by the numeric conversion functions (7.22.1, - 7.28.4.1). - -- The collation sequence of the execution character set (7.23.4.3, 7.28.4.4.2). - - -[page 573] - - -- The contents of the error message strings set up by the strerror function - (7.23.6.2). - -- The formats for time and date (7.26.3.5, 7.28.5.1). - -- Character mappings that are supported by the towctrans function (7.29.1). - -- Character classifications that are supported by the iswctype function (7.29.1). - J.5 Common extensions -1 The following extensions are widely used in many systems, but are not portable to all - implementations. The inclusion of any extension that may cause a strictly conforming - program to become invalid renders an implementation nonconforming. Examples of such - extensions are new keywords, extra library functions declared in standard headers, or - predefined macros with names that do not begin with an underscore. - J.5.1 Environment arguments -1 In a hosted environment, the main function receives a third argument, char *envp[], - that points to a null-terminated array of pointers to char, each of which points to a string - that provides information about the environment for this execution of the program - (5.1.2.2.1). - J.5.2 Specialized identifiers -1 Characters other than the underscore _, letters, and digits, that are not part of the basic - source character set (such as the dollar sign $, or characters in national character sets) - may appear in an identifier (6.4.2). - J.5.3 Lengths and cases of identifiers -1 All characters in identifiers (with or without external linkage) are significant (6.4.2). - J.5.4 Scopes of identifiers -1 A function identifier, or the identifier of an object the declaration of which contains the - keyword extern, has file scope (6.2.1). - J.5.5 Writable string literals -1 String literals are modifiable (in which case, identical string literals should denote distinct - objects) (6.4.5). - - - - -[page 574] - - J.5.6 Other arithmetic types -1 Additional arithmetic types, such as __int128 or double double, and their - appropriate conversions are defined (6.2.5, 6.3.1). Additional floating types may have - more range or precision than long double, may be used for evaluating expressions of - other floating types, and may be used to define float_t or double_t. - J.5.7 Function pointer casts -1 A pointer to an object or to void may be cast to a pointer to a function, allowing data to - be invoked as a function (6.5.4). -2 A pointer to a function may be cast to a pointer to an object or to void, allowing a - function to be inspected or modified (for example, by a debugger) (6.5.4). - J.5.8 Extended bit-field types -1 A bit-field may be declared with a type other than _Bool, unsigned int, or - signed int, with an appropriate maximum width (6.7.2.1). - J.5.9 The fortran keyword -1 The fortran function specifier may be used in a function declaration to indicate that - calls suitable for FORTRAN should be generated, or that a different representation for the - external name is to be generated (6.7.4). - J.5.10 The asm keyword -1 The asm keyword may be used to insert assembly language directly into the translator - output (6.8). The most common implementation is via a statement of the form: - asm ( character-string-literal ); - J.5.11 Multiple external definitions -1 There may be more than one external definition for the identifier of an object, with or - without the explicit use of the keyword extern; if the definitions disagree, or more than - one is initialized, the behavior is undefined (6.9.2). - J.5.12 Predefined macro names -1 Macro names that do not begin with an underscore, describing the translation and - execution environments, are defined by the implementation before translation begins - (6.10.8). - - - - -[page 575] - - J.5.13 Floating-point status flags -1 If any floating-point status flags are set on normal termination after all calls to functions - registered by the atexit function have been made (see 7.22.4.4), the implementation - writes some diagnostics indicating the fact to the stderr stream, if it is still open, - J.5.14 Extra arguments for signal handlers -1 Handlers for specific signals are called with extra arguments in addition to the signal - number (7.14.1.1). - J.5.15 Additional stream types and file-opening modes -1 Additional mappings from files to streams are supported (7.21.2). -2 Additional file-opening modes may be specified by characters appended to the mode - argument of the fopen function (7.21.5.3). - J.5.16 Defined file position indicator -1 The file position indicator is decremented by each successful call to the ungetc or - ungetwc function for a text stream, except if its value was zero before a call (7.21.7.10, - 7.28.3.10). - J.5.17 Math error reporting -1 Functions declared in and raise SIGFPE to report errors - instead of, or in addition to, setting errno or raising floating-point exceptions (7.3, - 7.12). - - - - -[page 576] - - Annex K - (normative) - Bounds-checking interfaces - K.1 Background -1 Traditionally, the C Library has contained many functions that trust the programmer to - provide output character arrays big enough to hold the result being produced. Not only - do these functions not check that the arrays are big enough, they frequently lack the - information needed to perform such checks. While it is possible to write safe, robust, and - error-free code using the existing library, the library tends to promote programming styles - that lead to mysterious failures if a result is too big for the provided array. -2 A common programming style is to declare character arrays large enough to handle most - practical cases. However, if these arrays are not large enough to handle the resulting - strings, data can be written past the end of the array overwriting other data and program - structures. The program never gets any indication that a problem exists, and so never has - a chance to recover or to fail gracefully. -3 Worse, this style of programming has compromised the security of computers and - networks. Buffer overflows can often be exploited to run arbitrary code with the - permissions of the vulnerable (defective) program. -4 If the programmer writes runtime checks to verify lengths before calling library - functions, then those runtime checks frequently duplicate work done inside the library - functions, which discover string lengths as a side effect of doing their job. -5 This annex provides alternative library functions that promote safer, more secure - programming. The alternative functions verify that output buffers are large enough for - the intended result and return a failure indicator if they are not. Data is never written past - the end of an array. All string results are null terminated. -6 This annex also addresses another problem that complicates writing robust code: - functions that are not reentrant because they return pointers to static objects owned by the - function. Such functions can be troublesome since a previously returned result can - change if the function is called again, perhaps by another thread. - - - - -[page 577] - - K.2 Scope -1 This annex specifies a series of optional extensions that can be useful in the mitigation of - security vulnerabilities in programs, and comprise new functions, macros, and types - declared or defined in existing standard headers. -2 An implementation that defines __STDC_LIB_EXT1__ shall conform to the - specifications in this annex.361) -3 Subclause K.3 should be read as if it were merged into the parallel structure of named - subclauses of clause 7. - K.3 Library - K.3.1 Introduction - K.3.1.1 Standard headers -1 The functions, macros, and types declared or defined in K.3 and its subclauses are not - declared or defined by their respective headers if __STDC_WANT_LIB_EXT1__ is - defined as a macro which expands to the integer constant 0 at the point in the source file - where the appropriate header is first included. -2 The functions, macros, and types declared or defined in K.3 and its subclauses are - declared and defined by their respective headers if __STDC_WANT_LIB_EXT1__ is - defined as a macro which expands to the integer constant 1 at the point in the source file - where the appropriate header is first included.362) -3 It is implementation-defined whether the functions, macros, and types declared or defined - in K.3 and its subclauses are declared or defined by their respective headers if - __STDC_WANT_LIB_EXT1__ is not defined as a macro at the point in the source file - where the appropriate header is first included.363) -4 Within a preprocessing translation unit, __STDC_WANT_LIB_EXT1__ shall be - defined identically for all inclusions of any headers from subclause K.3. If - __STDC_WANT_LIB_EXT1__ is defined differently for any such inclusion, the - implementation shall issue a diagnostic as if a preprocessor error directive were used. - - - 361) Implementations that do not define __STDC_LIB_EXT1__ are not required to conform to these - specifications. - 362) Future revisions of this International Standard may define meanings for other values of - __STDC_WANT_LIB_EXT1__. - 363) Subclause 7.1.3 reserves certain names and patterns of names that an implementation may use in - headers. All other names are not reserved, and a conforming implementation is not permitted to use - them. While some of the names defined in K.3 and its subclauses are reserved, others are not. If an - unreserved name is defined in a header when __STDC_WANT_LIB_EXT1__ is defined as 0, the - implementation is not conforming. - -[page 578] - - K.3.1.2 Reserved identifiers -1 Each macro name in any of the following subclauses is reserved for use as specified if it - is defined by any of its associated headers when included; unless explicitly stated - otherwise (see 7.1.4). -2 All identifiers with external linkage in any of the following subclauses are reserved for - use as identifiers with external linkage if any of them are used by the program. None of - them are reserved if none of them are used. -3 Each identifier with file scope listed in any of the following subclauses is reserved for use - as a macro name and as an identifier with file scope in the same name space if it is - defined by any of its associated headers when included. - K.3.1.3 Use of errno -1 An implementation may set errno for the functions defined in this annex, but is not - required to. - K.3.1.4 Runtime-constraint violations -1 Most functions in this annex include as part of their specification a list of runtime- - constraints. These runtime-constraints are requirements on the program using the - library.364) -2 Implementations shall verify that the runtime-constraints for a function are not violated - by the program. If a runtime-constraint is violated, the implementation shall call the - currently registered runtime-constraint handler (see set_constraint_handler_s - in ). Multiple runtime-constraint violations in the same call to a library - function result in only one call to the runtime-constraint handler. It is unspecified which - one of the multiple runtime-constraint violations cause the handler to be called. -3 If the runtime-constraints section for a function states an action to be performed when a - runtime-constraint violation occurs, the function shall perform the action before calling - the runtime-constraint handler. If the runtime-constraints section lists actions that are - prohibited when a runtime-constraint violation occurs, then such actions are prohibited to - the function both before calling the handler and after the handler returns. -4 The runtime-constraint handler might not return. If the handler does return, the library - function whose runtime-constraint was violated shall return some indication of failure as - given by the returns section in the function's specification. - - - - 364) Although runtime-constraints replace many cases of undefined behavior, undefined behavior still - exists in this annex. Implementations are free to detect any case of undefined behavior and treat it as a - runtime-constraint violation by calling the runtime-constraint handler. This license comes directly - from the definition of undefined behavior. - -[page 579] - - K.3.2 Errors -1 The header defines a type. -2 The type is - errno_t - which is type int.365) - K.3.3 Common definitions -1 The header defines a type. -2 The type is - rsize_t - which is the type size_t.366) - K.3.4 Integer types -1 The header defines a macro. -2 The macro is - RSIZE_MAX - which expands to a value367) of type size_t. Functions that have parameters of type - rsize_t consider it a runtime-constraint violation if the values of those parameters are - greater than RSIZE_MAX. - Recommended practice -3 Extremely large object sizes are frequently a sign that an object's size was calculated - incorrectly. For example, negative numbers appear as very large positive numbers when - converted to an unsigned type like size_t. Also, some implementations do not support - objects as large as the maximum value that can be represented by type size_t. -4 For those reasons, it is sometimes beneficial to restrict the range of object sizes to detect - programming errors. For implementations targeting machines with large address spaces, - it is recommended that RSIZE_MAX be defined as the smaller of the size of the largest - object supported or (SIZE_MAX >> 1), even if this limit is smaller than the size of - some legitimate, but very large, objects. Implementations targeting machines with small - address spaces may wish to define RSIZE_MAX as SIZE_MAX, which means that there - - 365) As a matter of programming style, errno_t may be used as the type of something that deals only - with the values that might be found in errno. For example, a function which returns the value of - errno might be declared as having the return type errno_t. - 366) See the description of the RSIZE_MAX macro in . - 367) The macro RSIZE_MAX need not expand to a constant expression. - -[page 580] - - is no object size that is considered a runtime-constraint violation. - K.3.5 Input/output -1 The header defines several macros and two types. -2 The macros are - L_tmpnam_s - which expands to an integer constant expression that is the size needed for an array of - char large enough to hold a temporary file name string generated by the tmpnam_s - function; - TMP_MAX_S - which expands to an integer constant expression that is the maximum number of unique - file names that can be generated by the tmpnam_s function. -3 The types are - errno_t - which is type int; and - rsize_t - which is the type size_t. - K.3.5.1 Operations on files - K.3.5.1.1 The tmpfile_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t tmpfile_s(FILE * restrict * restrict streamptr); - Runtime-constraints -2 streamptr shall not be a null pointer. -3 If there is a runtime-constraint violation, tmpfile_s does not attempt to create a file. - Description -4 The tmpfile_s function creates a temporary binary file that is different from any other - existing file and that will automatically be removed when it is closed or at program - termination. If the program terminates abnormally, whether an open temporary file is - removed is implementation-defined. The file is opened for update with "wb+" mode - with the meaning that mode has in the fopen_s function (including the mode's effect - on exclusive access and file permissions). - - -[page 581] - -5 If the file was created successfully, then the pointer to FILE pointed to by streamptr - will be set to the pointer to the object controlling the opened file. Otherwise, the pointer - to FILE pointed to by streamptr will be set to a null pointer. - Recommended practice - It should be possible to open at least TMP_MAX_S temporary files during the lifetime of - the program (this limit may be shared with tmpnam_s) and there should be no limit on - the number simultaneously open other than this limit and any limit on the number of open - files (FOPEN_MAX). - Returns -6 The tmpfile_s function returns zero if it created the file. If it did not create the file or - there was a runtime-constraint violation, tmpfile_s returns a nonzero value. - K.3.5.1.2 The tmpnam_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t tmpnam_s(char *s, rsize_t maxsize); - Runtime-constraints -2 s shall not be a null pointer. maxsize shall be less than or equal to RSIZE_MAX. - maxsize shall be greater than the length of the generated file name string. - Description -3 The tmpnam_s function generates a string that is a valid file name and that is not the - same as the name of an existing file.368) The function is potentially capable of generating - TMP_MAX_S different strings, but any or all of them may already be in use by existing - files and thus not be suitable return values. The lengths of these strings shall be less than - the value of the L_tmpnam_s macro. -4 The tmpnam_s function generates a different string each time it is called. -5 It is assumed that s points to an array of at least maxsize characters. This array will be - set to generated string, as specified below. - - - - 368) Files created using strings generated by the tmpnam_s function are temporary only in the sense that - their names should not collide with those generated by conventional naming rules for the - implementation. It is still necessary to use the remove function to remove such files when their use - is ended, and before program termination. Implementations should take care in choosing the patterns - used for names returned by tmpnam_s. For example, making a thread id part of the names avoids the - race condition and possible conflict when multiple programs run simultaneously by the same user - generate the same temporary file names. - -[page 582] - -6 The implementation shall behave as if no library function except tmpnam calls the - tmpnam_s function.369) - Recommended practice -7 After a program obtains a file name using the tmpnam_s function and before the - program creates a file with that name, the possibility exists that someone else may create - a file with that same name. To avoid this race condition, the tmpfile_s function - should be used instead of tmpnam_s when possible. One situation that requires the use - of the tmpnam_s function is when the program needs to create a temporary directory - rather than a temporary file. - Returns -8 If no suitable string can be generated, or if there is a runtime-constraint violation, the - tmpnam_s function writes a null character to s[0] (only if s is not null and maxsize - is greater than zero) and returns a nonzero value. -9 Otherwise, the tmpnam_s function writes the string in the array pointed to by s and - returns zero. - Environmental limits -10 The value of the macro TMP_MAX_S shall be at least 25. - K.3.5.2 File access functions - K.3.5.2.1 The fopen_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t fopen_s(FILE * restrict * restrict streamptr, - const char * restrict filename, - const char * restrict mode); - Runtime-constraints -2 None of streamptr, filename, or mode shall be a null pointer. -3 If there is a runtime-constraint violation, fopen_s does not attempt to open a file. - Furthermore, if streamptr is not a null pointer, fopen_s sets *streamptr to the - null pointer. - - - - - 369) An implementation may have tmpnam call tmpnam_s (perhaps so there is only one naming - convention for temporary files), but this is not required. - -[page 583] - - Description -4 The fopen_s function opens the file whose name is the string pointed to by - filename, and associates a stream with it. -5 The mode string shall be as described for fopen, with the addition that modes starting - with the character 'w' or 'a' may be preceded by the character 'u', see below: - uw truncate to zero length or create text file for writing, default - permissions - uwx create text file for writing, default permissions - ua append; open or create text file for writing at end-of-file, default - permissions - uwb truncate to zero length or create binary file for writing, default - permissions - uwbx create binary file for writing, default permissions - uab append; open or create binary file for writing at end-of-file, default - permissions - uw+ truncate to zero length or create text file for update, default - permissions - uw+x create text file for update, default permissions - ua+ append; open or create text file for update, writing at end-of-file, - default permissions - uw+b or uwb+ truncate to zero length or create binary file for update, default - permissions - uw+bx or uwb+x create binary file for update, default permissions - ua+b or uab+ append; open or create binary file for update, writing at end-of-file, - default permissions -6 Opening a file with exclusive mode ('x' as the last character in the mode argument) - fails if the file already exists or cannot be created. -7 To the extent that the underlying system supports the concepts, files opened for writing - shall be opened with exclusive (also known as non-shared) access. If the file is being - created, and the first character of the mode string is not 'u', to the extent that the - underlying system supports it, the file shall have a file permission that prevents other - users on the system from accessing the file. If the file is being created and first character - of the mode string is 'u', then by the time the file has been closed, it shall have the - system default file access permissions.370) -8 If the file was opened successfully, then the pointer to FILE pointed to by streamptr - will be set to the pointer to the object controlling the opened file. Otherwise, the pointer - - - 370) These are the same permissions that the file would have been created with by fopen. - -[page 584] - - to FILE pointed to by streamptr will be set to a null pointer. - Returns -9 The fopen_s function returns zero if it opened the file. If it did not open the file or if - there was a runtime-constraint violation, fopen_s returns a nonzero value. - K.3.5.2.2 The freopen_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t freopen_s(FILE * restrict * restrict newstreamptr, - const char * restrict filename, - const char * restrict mode, - FILE * restrict stream); - Runtime-constraints -2 None of newstreamptr, mode, and stream shall be a null pointer. -3 If there is a runtime-constraint violation, freopen_s neither attempts to close any file - associated with stream nor attempts to open a file. Furthermore, if newstreamptr is - not a null pointer, fopen_s sets *newstreamptr to the null pointer. - Description -4 The freopen_s function opens the file whose name is the string pointed to by - filename and associates the stream pointed to by stream with it. The mode - argument has the same meaning as in the fopen_s function (including the mode's effect - on exclusive access and file permissions). -5 If filename is a null pointer, the freopen_s function attempts to change the mode of - the stream to that specified by mode, as if the name of the file currently associated with - the stream had been used. It is implementation-defined which changes of mode are - permitted (if any), and under what circumstances. -6 The freopen_s function first attempts to close any file that is associated with stream. - Failure to close the file is ignored. The error and end-of-file indicators for the stream are - cleared. -7 If the file was opened successfully, then the pointer to FILE pointed to by - newstreamptr will be set to the value of stream. Otherwise, the pointer to FILE - pointed to by newstreamptr will be set to a null pointer. - Returns -8 The freopen_s function returns zero if it opened the file. If it did not open the file or - there was a runtime-constraint violation, freopen_s returns a nonzero value. - -[page 585] - - K.3.5.3 Formatted input/output functions -1 Unless explicitly stated otherwise, if the execution of a function described in this - subclause causes copying to take place between objects that overlap, the objects take on - unspecified values. - K.3.5.3.1 The fprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int fprintf_s(FILE * restrict stream, - const char * restrict format, ...); - Runtime-constraints -2 Neither stream nor format shall be a null pointer. The %n specifier371) (modified or - not by flags, field width, or precision) shall not appear in the string pointed to by - format. Any argument to fprintf_s corresponding to a %s specifier shall not be a - null pointer. -3 If there is a runtime-constraint violation,372) the fprintf_s function does not attempt - to produce further output, and it is unspecified to what extent fprintf_s produced - output before discovering the runtime-constraint violation. - Description -4 The fprintf_s function is equivalent to the fprintf function except for the explicit - runtime-constraints listed above. - Returns -5 The fprintf_s function returns the number of characters transmitted, or a negative - value if an output error, encoding error, or runtime-constraint violation occurred. - - - - - 371) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - 372) Because an implementation may treat any undefined behavior as a runtime-constraint violation, an - implementation may treat any unsupported specifiers in the string pointed to by format as a runtime- - constraint violation. - -[page 586] - - K.3.5.3.2 The fscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int fscanf_s(FILE * restrict stream, - const char * restrict format, ...); - Runtime-constraints -2 Neither stream nor format shall be a null pointer. Any argument indirected though in - order to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation,373) the fscanf_s function does not attempt to - perform further input, and it is unspecified to what extent fscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The fscanf_s function is equivalent to fscanf except that the c, s, and [ conversion - specifiers apply to a pair of arguments (unless assignment suppression is indicated by a - *). The first of these arguments is the same as for fscanf. That argument is - immediately followed in the argument list by the second argument, which has type - rsize_t and gives the number of elements in the array pointed to by the first argument - of the pair. If the first argument points to a scalar object, it is considered to be an array of - one element.374) -5 A matching failure occurs if the number of elements in a receiving object is insufficient to - hold the converted input (including any trailing null character). - Returns -6 The fscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - - 373) Because an implementation may treat any undefined behavior as a runtime-constraint violation, an - implementation may treat any unsupported specifiers in the string pointed to by format as a runtime- - constraint violation. - 374) If the format is known at translation time, an implementation may issue a diagnostic for any argument - used to store the result from a c, s, or [ conversion specifier if that argument is not followed by an - argument of a type compatible with rsize_t. A limited amount of checking may be done if even if - the format is not known at translation time. For example, an implementation may issue a diagnostic - for each argument after format that has of type pointer to one of char, signed char, - unsigned char, or void that is not followed by an argument of a type compatible with - rsize_t. The diagnostic could warn that unless the pointer is being used with a conversion specifier - using the hh length modifier, a length argument must follow the pointer argument. Another useful - diagnostic could flag any non-pointer argument following format that did not have a type - compatible with rsize_t. - -[page 587] - - fscanf_s function returns the number of input items assigned, which can be fewer than - provided for, or even zero, in the event of an early matching failure. -7 EXAMPLE 1 The call: - #define __STDC_WANT_LIB_EXT1__ 1 - #include - /* ... */ - int n, i; float x; char name[50]; - n = fscanf_s(stdin, "%d%f%s", &i, &x, name, (rsize_t) 50); - with the input line: - 25 54.32E-1 thompson - will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence - thompson\0. - -8 EXAMPLE 2 The call: - #define __STDC_WANT_LIB_EXT1__ 1 - #include - /* ... */ - int n; char s[5]; - n = fscanf_s(stdin, "%s", s, sizeof s); - with the input line: - hello - will assign to n the value 0 since a matching failure occurred because the sequence hello\0 requires an - array of six characters to store it. - - K.3.5.3.3 The printf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int printf_s(const char * restrict format, ...); - Runtime-constraints -2 format shall not be a null pointer. The %n specifier375) (modified or not by flags, field - width, or precision) shall not appear in the string pointed to by format. Any argument - to printf_s corresponding to a %s specifier shall not be a null pointer. -3 If there is a runtime-constraint violation, the printf_s function does not attempt to - produce further output, and it is unspecified to what extent printf_s produced output - before discovering the runtime-constraint violation. - - - 375) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - -[page 588] - - Description -4 The printf_s function is equivalent to the printf function except for the explicit - runtime-constraints listed above. - Returns -5 The printf_s function returns the number of characters transmitted, or a negative - value if an output error, encoding error, or runtime-constraint violation occurred. - K.3.5.3.4 The scanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int scanf_s(const char * restrict format, ...); - Runtime-constraints -2 format shall not be a null pointer. Any argument indirected though in order to store - converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the scanf_s function does not attempt to - perform further input, and it is unspecified to what extent scanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The scanf_s function is equivalent to fscanf_s with the argument stdin - interposed before the arguments to scanf_s. - Returns -5 The scanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - scanf_s function returns the number of input items assigned, which can be fewer than - provided for, or even zero, in the event of an early matching failure. - K.3.5.3.5 The snprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int snprintf_s(char * restrict s, rsize_t n, - const char * restrict format, ...); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The %n specifier376) (modified or not by flags, field width, or - precision) shall not appear in the string pointed to by format. Any argument to -[page 589] - - snprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding - error shall occur. -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the snprintf_s function sets s[0] to the - null character. - Description -4 The snprintf_s function is equivalent to the snprintf function except for the - explicit runtime-constraints listed above. -5 The snprintf_s function, unlike sprintf_s, will truncate the result to fit within the - array pointed to by s. - Returns -6 The snprintf_s function returns the number of characters that would have been - written had n been sufficiently large, not counting the terminating null character, or a - negative value if a runtime-constraint violation occurred. Thus, the null-terminated - output has been completely written if and only if the returned value is nonnegative and - less than n. - K.3.5.3.6 The sprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int sprintf_s(char * restrict s, rsize_t n, - const char * restrict format, ...); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The number of characters (including the trailing null) required for the - result to be written to the array pointed to by s shall not be greater than n. The %n - specifier377) (modified or not by flags, field width, or precision) shall not appear in the - string pointed to by format. Any argument to sprintf_s corresponding to a %s - specifier shall not be a null pointer. No encoding error shall occur. - - - - 376) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - 377) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - -[page 590] - -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the sprintf_s function sets s[0] to the - null character. - Description -4 The sprintf_s function is equivalent to the sprintf function except for the - parameter n and the explicit runtime-constraints listed above. -5 The sprintf_s function, unlike snprintf_s, treats a result too big for the array - pointed to by s as a runtime-constraint violation. - Returns -6 If no runtime-constraint violation occurred, the sprintf_s function returns the number - of characters written in the array, not counting the terminating null character. If an - encoding error occurred, sprintf_s returns a negative value. If any other runtime- - constraint violation occurred, sprintf_s returns zero. - K.3.5.3.7 The sscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int sscanf_s(const char * restrict s, - const char * restrict format, ...); - Runtime-constraints -2 Neither s nor format shall be a null pointer. Any argument indirected though in order - to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the sscanf_s function does not attempt to - perform further input, and it is unspecified to what extent sscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The sscanf_s function is equivalent to fscanf_s, except that input is obtained from - a string (specified by the argument s) rather than from a stream. Reaching the end of the - string is equivalent to encountering end-of-file for the fscanf_s function. If copying - takes place between objects that overlap, the objects take on unspecified values. - Returns -5 The sscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - sscanf_s function returns the number of input items assigned, which can be fewer than - provided for, or even zero, in the event of an early matching failure. - -[page 591] - - K.3.5.3.8 The vfprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vfprintf_s(FILE * restrict stream, - const char * restrict format, - va_list arg); - Runtime-constraints -2 Neither stream nor format shall be a null pointer. The %n specifier378) (modified or - not by flags, field width, or precision) shall not appear in the string pointed to by - format. Any argument to vfprintf_s corresponding to a %s specifier shall not be a - null pointer. -3 If there is a runtime-constraint violation, the vfprintf_s function does not attempt to - produce further output, and it is unspecified to what extent vfprintf_s produced - output before discovering the runtime-constraint violation. - Description -4 The vfprintf_s function is equivalent to the vfprintf function except for the - explicit runtime-constraints listed above. - Returns -5 The vfprintf_s function returns the number of characters transmitted, or a negative - value if an output error, encoding error, or runtime-constraint violation occurred. - K.3.5.3.9 The vfscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vfscanf_s(FILE * restrict stream, - const char * restrict format, - va_list arg); - - - - - 378) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - -[page 592] - - Runtime-constraints -2 Neither stream nor format shall be a null pointer. Any argument indirected though in - order to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the vfscanf_s function does not attempt to - perform further input, and it is unspecified to what extent vfscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The vfscanf_s function is equivalent to fscanf_s, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vfscanf_s function does not invoke the - va_end macro.379) - Returns -5 The vfscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - vfscanf_s function returns the number of input items assigned, which can be fewer - than provided for, or even zero, in the event of an early matching failure. - K.3.5.3.10 The vprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vprintf_s(const char * restrict format, - va_list arg); - Runtime-constraints -2 format shall not be a null pointer. The %n specifier380) (modified or not by flags, field - width, or precision) shall not appear in the string pointed to by format. Any argument - to vprintf_s corresponding to a %s specifier shall not be a null pointer. -3 If there is a runtime-constraint violation, the vprintf_s function does not attempt to - produce further output, and it is unspecified to what extent vprintf_s produced output - before discovering the runtime-constraint violation. - - 379) As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s, - vsprintf_s, and vsscanf_s invoke the va_arg macro, the value of arg after the return is - indeterminate. - 380) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - -[page 593] - - Description -4 The vprintf_s function is equivalent to the vprintf function except for the explicit - runtime-constraints listed above. - Returns -5 The vprintf_s function returns the number of characters transmitted, or a negative - value if an output error, encoding error, or runtime-constraint violation occurred. - K.3.5.3.11 The vscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vscanf_s(const char * restrict format, - va_list arg); - Runtime-constraints -2 format shall not be a null pointer. Any argument indirected though in order to store - converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the vscanf_s function does not attempt to - perform further input, and it is unspecified to what extent vscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The vscanf_s function is equivalent to scanf_s, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vscanf_s function does not invoke the - va_end macro.381) - Returns -5 The vscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - vscanf_s function returns the number of input items assigned, which can be fewer than - provided for, or even zero, in the event of an early matching failure. - - - - - 381) As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s, - vsprintf_s, and vsscanf_s invoke the va_arg macro, the value of arg after the return is - indeterminate. - -[page 594] - - K.3.5.3.12 The vsnprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vsnprintf_s(char * restrict s, rsize_t n, - const char * restrict format, - va_list arg); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The %n specifier382) (modified or not by flags, field width, or - precision) shall not appear in the string pointed to by format. Any argument to - vsnprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding - error shall occur. -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the vsnprintf_s function sets s[0] to the - null character. - Description -4 The vsnprintf_s function is equivalent to the vsnprintf function except for the - explicit runtime-constraints listed above. -5 The vsnprintf_s function, unlike vsprintf_s, will truncate the result to fit within - the array pointed to by s. - Returns -6 The vsnprintf_s function returns the number of characters that would have been - written had n been sufficiently large, not counting the terminating null character, or a - negative value if a runtime-constraint violation occurred. Thus, the null-terminated - output has been completely written if and only if the returned value is nonnegative and - less than n. - - - - - 382) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - -[page 595] - - K.3.5.3.13 The vsprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vsprintf_s(char * restrict s, rsize_t n, - const char * restrict format, - va_list arg); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The number of characters (including the trailing null) required for the - result to be written to the array pointed to by s shall not be greater than n. The %n - specifier383) (modified or not by flags, field width, or precision) shall not appear in the - string pointed to by format. Any argument to vsprintf_s corresponding to a %s - specifier shall not be a null pointer. No encoding error shall occur. -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the vsprintf_s function sets s[0] to the - null character. - Description -4 The vsprintf_s function is equivalent to the vsprintf function except for the - parameter n and the explicit runtime-constraints listed above. -5 The vsprintf_s function, unlike vsnprintf_s, treats a result too big for the array - pointed to by s as a runtime-constraint violation. - Returns -6 If no runtime-constraint violation occurred, the vsprintf_s function returns the - number of characters written in the array, not counting the terminating null character. If - an encoding error occurred, vsprintf_s returns a negative value. If any other - runtime-constraint violation occurred, vsprintf_s returns zero. - - - - - 383) It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed - at by format when those characters are not a interpreted as a %n specifier. For example, if the entire - format string was %%n. - -[page 596] - - K.3.5.3.14 The vsscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vsscanf_s(const char * restrict s, - const char * restrict format, - va_list arg); - Runtime-constraints -2 Neither s nor format shall be a null pointer. Any argument indirected though in order - to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the vsscanf_s function does not attempt to - perform further input, and it is unspecified to what extent vsscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The vsscanf_s function is equivalent to sscanf_s, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vsscanf_s function does not invoke the - va_end macro.384) - Returns -5 The vsscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - vscanf_s function returns the number of input items assigned, which can be fewer than - provided for, or even zero, in the event of an early matching failure. - K.3.5.4 Character input/output functions - K.3.5.4.1 The gets_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - char *gets_s(char *s, rsize_t n); - - - - - 384) As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s, - vsprintf_s, and vsscanf_s invoke the va_arg macro, the value of arg after the return is - indeterminate. - -[page 597] - - Runtime-constraints -2 s shall not be a null pointer. n shall neither be equal to zero nor be greater than - RSIZE_MAX. A new-line character, end-of-file, or read error shall occur within reading - n-1 characters from stdin.385) -3 If there is a runtime-constraint violation, s[0] is set to the null character, and characters - are read and discarded from stdin until a new-line character is read, or end-of-file or a - read error occurs. - Description -4 The gets_s function reads at most one less than the number of characters specified by n - from the stream pointed to by stdin, into the array pointed to by s. No additional - characters are read after a new-line character (which is discarded) or after end-of-file. - The discarded new-line character does not count towards number of characters read. A - null character is written immediately after the last character read into the array. -5 If end-of-file is encountered and no characters have been read into the array, or if a read - error occurs during the operation, then s[0] is set to the null character, and the other - elements of s take unspecified values. - Recommended practice -6 The fgets function allows properly-written programs to safely process input lines too - long to store in the result array. In general this requires that callers of fgets pay - attention to the presence or absence of a new-line character in the result array. Consider - using fgets (along with any needed processing based on new-line characters) instead of - gets_s. - Returns -7 The gets_s function returns s if successful. If there was a runtime-constraint violation, - or if end-of-file is encountered and no characters have been read into the array, or if a - read error occurs during the operation, then a null pointer is returned. - - - - - 385) The gets_s function, unlike the historical gets function, makes it a runtime-constraint violation for - a line of input to overflow the buffer to store it. Unlike the fgets function, gets_s maintains a - one-to-one relationship between input lines and successful calls to gets_s. Programs that use gets - expect such a relationship. - -[page 598] - - K.3.6 General utilities -1 The header defines three types. -2 The types are - errno_t - which is type int; and - rsize_t - which is the type size_t; and - constraint_handler_t - which has the following definition - typedef void (*constraint_handler_t)( - const char * restrict msg, - void * restrict ptr, - errno_t error); - K.3.6.1 Runtime-constraint handling - K.3.6.1.1 The set_constraint_handler_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - constraint_handler_t set_constraint_handler_s( - constraint_handler_t handler); - Description -2 The set_constraint_handler_s function sets the runtime-constraint handler to - be handler. The runtime-constraint handler is the function to be called when a library - function detects a runtime-constraint violation. Only the most recent handler registered - with set_constraint_handler_s is called when a runtime-constraint violation - occurs. -3 When the handler is called, it is passed the following arguments in the following order: - 1. A pointer to a character string describing the runtime-constraint violation. - 2. A null pointer or a pointer to an implementation defined object. - 3. If the function calling the handler has a return type declared as errno_t, the - return value of the function is passed. Otherwise, a positive value of type - errno_t is passed. - - - -[page 599] - -4 The implementation has a default constraint handler that is used if no calls to the - set_constraint_handler_s function have been made. The behavior of the - default handler is implementation-defined, and it may cause the program to exit or abort. -5 If the handler argument to set_constraint_handler_s is a null pointer, the - implementation default handler becomes the current constraint handler. - Returns -6 The set_constraint_handler_s function returns a pointer to the previously - registered handler.386) - K.3.6.1.2 The abort_handler_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - void abort_handler_s( - const char * restrict msg, - void * restrict ptr, - errno_t error); - Description -2 A pointer to the abort_handler_s function shall be a suitable argument to the - set_constraint_handler_s function. -3 The abort_handler_s function writes a message on the standard error stream in an - implementation-defined format. The message shall include the string pointed to by msg. - The abort_handler_s function then calls the abort function.387) - Returns -4 The abort_handler_s function does not return to its caller. - - - - - 386) If the previous handler was registered by calling set_constraint_handler_s with a null - pointer argument, a pointer to the implementation default handler is returned (not NULL). - 387) Many implementations invoke a debugger when the abort function is called. - -[page 600] - - K.3.6.1.3 The ignore_handler_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - void ignore_handler_s( - const char * restrict msg, - void * restrict ptr, - errno_t error); - Description -2 A pointer to the ignore_handler_s function shall be a suitable argument to the - set_constraint_handler_s function. -3 The ignore_handler_s function simply returns to its caller.388) - Returns -4 The ignore_handler_s function returns no value. - K.3.6.2 Communication with the environment - K.3.6.2.1 The getenv_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t getenv_s(size_t * restrict len, - char * restrict value, rsize_t maxsize, - const char * restrict name); - Runtime-constraints -2 name shall not be a null pointer. maxsize shall neither equal zero nor be greater than - RSIZE_MAX. If maxsize is not equal to zero, then value shall not be a null pointer. -3 If there is a runtime-constraint violation, the integer pointed to by len is set to 0 (if len - is not null), and the environment list is not searched. - Description -4 The getenv_s function searches an environment list, provided by the host environment, - for a string that matches the string pointed to by name. - - - 388) If the runtime-constraint handler is set to the ignore_handler_s function, any library function in - which a runtime-constraint violation occurs will return to its caller. The caller can determine whether - a runtime-constraint violation occurred based on the library function's specification (usually, the - library function returns a nonzero errno_t). - -[page 601] - -5 If that name is found then getenv_s performs the following actions. If len is not a - null pointer, the length of the string associated with the matched list member is stored in - the integer pointed to by len. If the length of the associated string is less than maxsize, - then the associated string is copied to the array pointed to by value. -6 If that name is not found then getenv_s performs the following actions. If len is not - a null pointer, zero is stored in the integer pointed to by len. If maxsize is greater than - zero, then value[0] is set to the null character. -7 The set of environment names and the method for altering the environment list are - implementation-defined. - Returns -8 The getenv_s function returns zero if the specified name is found and the associated - string was successfully stored in value. Otherwise, a nonzero value is returned. - K.3.6.3 Searching and sorting utilities -1 These utilities make use of a comparison function to search or sort arrays of unspecified - type. Where an argument declared as size_t nmemb specifies the length of the array - for a function, if nmemb has the value zero on a call to that function, then the comparison - function is not called, a search finds no matching element, sorting performs no - rearrangement, and the pointer to the array may be null. -2 The implementation shall ensure that the second argument of the comparison function - (when called from bsearch_s), or both arguments (when called from qsort_s), are - pointers to elements of the array.389) The first argument when called from bsearch_s - shall equal key. -3 The comparison function shall not alter the contents of either the array or search key. The - implementation may reorder elements of the array between calls to the comparison - function, but shall not otherwise alter the contents of any individual element. -4 When the same objects (consisting of size bytes, irrespective of their current positions - in the array) are passed more than once to the comparison function, the results shall be - consistent with one another. That is, for qsort_s they shall define a total ordering on - the array, and for bsearch_s the same object shall always compare the same way with - the key. - - - - - 389) That is, if the value passed is p, then the following expressions are always valid and nonzero: - ((char *)p - (char *)base) % size == 0 - (char *)p >= (char *)base - (char *)p < (char *)base + nmemb * size - - -[page 602] - -5 A sequence point occurs immediately before and immediately after each call to the - comparison function, and also between any call to the comparison function and any - movement of the objects passed as arguments to that call. - K.3.6.3.1 The bsearch_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - void *bsearch_s(const void *key, const void *base, - rsize_t nmemb, rsize_t size, - int (*compar)(const void *k, const void *y, - void *context), - void *context); - Runtime-constraints -2 Neither nmemb nor size shall be greater than RSIZE_MAX. If nmemb is not equal to - zero, then none of key, base, or compar shall be a null pointer. -3 If there is a runtime-constraint violation, the bsearch_s function does not search the - array. - Description -4 The bsearch_s function searches an array of nmemb objects, the initial element of - which is pointed to by base, for an element that matches the object pointed to by key. - The size of each element of the array is specified by size. -5 The comparison function pointed to by compar is called with three arguments. The first - two point to the key object and to an array element, in that order. The function shall - return an integer less than, equal to, or greater than zero if the key object is considered, - respectively, to be less than, to match, or to be greater than the array element. The array - shall consist of: all the elements that compare less than, all the elements that compare - equal to, and all the elements that compare greater than the key object, in that order.390) - The third argument to the comparison function is the context argument passed to - bsearch_s. The sole use of context by bsearch_s is to pass it to the comparison - function.391) - - - - - 390) In practice, this means that the entire array has been sorted according to the comparison function. - 391) The context argument is for the use of the comparison function in performing its duties. For - example, it might specify a collating sequence used by the comparison function. - -[page 603] - - Returns -6 The bsearch_s function returns a pointer to a matching element of the array, or a null - pointer if no match is found or there is a runtime-constraint violation. If two elements - compare as equal, which element is matched is unspecified. - K.3.6.3.2 The qsort_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t qsort_s(void *base, rsize_t nmemb, rsize_t size, - int (*compar)(const void *x, const void *y, - void *context), - void *context); - Runtime-constraints -2 Neither nmemb nor size shall be greater than RSIZE_MAX. If nmemb is not equal to - zero, then neither base nor compar shall be a null pointer. -3 If there is a runtime-constraint violation, the qsort_s function does not sort the array. - Description -4 The qsort_s function sorts an array of nmemb objects, the initial element of which is - pointed to by base. The size of each object is specified by size. -5 The contents of the array are sorted into ascending order according to a comparison - function pointed to by compar, which is called with three arguments. The first two - point to the objects being compared. The function shall return an integer less than, equal - to, or greater than zero if the first argument is considered to be respectively less than, - equal to, or greater than the second. The third argument to the comparison function is the - context argument passed to qsort_s. The sole use of context by qsort_s is to - pass it to the comparison function.392) -6 If two elements compare as equal, their relative order in the resulting sorted array is - unspecified. - Returns -7 The qsort_s function returns zero if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - - - - - 392) The context argument is for the use of the comparison function in performing its duties. For - example, it might specify a collating sequence used by the comparison function. - -[page 604] - - K.3.6.4 Multibyte/wide character conversion functions -1 The behavior of the multibyte character functions is affected by the LC_CTYPE category - of the current locale. For a state-dependent encoding, each function is placed into its - initial conversion state by a call for which its character pointer argument, s, is a null - pointer. Subsequent calls with s as other than a null pointer cause the internal conversion - state of the function to be altered as necessary. A call with s as a null pointer causes - these functions to set the int pointed to by their status argument to a nonzero value if - encodings have state dependency, and zero otherwise.393) Changing the LC_CTYPE - category causes the conversion state of these functions to be indeterminate. - K.3.6.4.1 The wctomb_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wctomb_s(int * restrict status, - char * restrict s, - rsize_t smax, - wchar_t wc); - Runtime-constraints -2 Let n denote the number of bytes needed to represent the multibyte character - corresponding to the wide character given by wc (including any shift sequences). -3 If s is not a null pointer, then smax shall not be less than n, and smax shall not be - greater than RSIZE_MAX. If s is a null pointer, then smax shall equal zero. -4 If there is a runtime-constraint violation, wctomb_s does not modify the int pointed to - by status, and if s is not a null pointer, no more than smax elements in the array - pointed to by s will be accessed. - Description -5 The wctomb_s function determines n and stores the multibyte character representation - of wc in the array whose first element is pointed to by s (if s is not a null pointer). The - number of characters stored never exceeds MB_CUR_MAX or smax. If wc is a null wide - character, a null byte is stored, preceded by any shift sequence needed to restore the - initial shift state, and the function is left in the initial conversion state. -6 The implementation shall behave as if no library function calls the wctomb_s function. - - - - 393) If the locale employs special bytes to change the shift state, these bytes do not produce separate wide - character codes, but are grouped with an adjacent multibyte character. - -[page 605] - -7 If s is a null pointer, the wctomb_s function stores into the int pointed to by status a - nonzero or zero value, if multibyte character encodings, respectively, do or do not have - state-dependent encodings. -8 If s is not a null pointer, the wctomb_s function stores into the int pointed to by - status either n or -1 if wc, respectively, does or does not correspond to a valid - multibyte character. -9 In no case will the int pointed to by status be set to a value greater than the - MB_CUR_MAX macro. - Returns -10 The wctomb_s function returns zero if successful, and a nonzero value if there was a - runtime-constraint violation or wc did not correspond to a valid multibyte character. - K.3.6.5 Multibyte/wide string conversion functions -1 The behavior of the multibyte string functions is affected by the LC_CTYPE category of - the current locale. - K.3.6.5.1 The mbstowcs_s function - Synopsis -1 #include - errno_t mbstowcs_s(size_t * restrict retval, - wchar_t * restrict dst, rsize_t dstmax, - const char * restrict src, rsize_t len); - Runtime-constraints -2 Neither retval nor src shall be a null pointer. If dst is not a null pointer, then - neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null pointer, - then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall not equal - zero. If dst is not a null pointer and len is not less than dstmax, then a null character - shall occur within the first dstmax multibyte characters of the array pointed to by src. -3 If there is a runtime-constraint violation, then mbstowcs_s does the following. If - retval is not a null pointer, then mbstowcs_s sets *retval to (size_t)(-1). If - dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX, - then mbstowcs_s sets dst[0] to the null wide character. - Description -4 The mbstowcs_s function converts a sequence of multibyte characters that begins in - the initial shift state from the array pointed to by src into a sequence of corresponding - wide characters. If dst is not a null pointer, the converted characters are stored into the - array pointed to by dst. Conversion continues up to and including a terminating null - character, which is also stored. Conversion stops earlier in two cases: when a sequence of -[page 606] - - bytes is encountered that does not form a valid multibyte character, or (if dst is not a - null pointer) when len wide characters have been stored into the array pointed to by - dst.394) If dst is not a null pointer and no null wide character was stored into the array - pointed to by dst, then dst[len] is set to the null wide character. Each conversion - takes place as if by a call to the mbrtowc function. -5 Regardless of whether dst is or is not a null pointer, if the input conversion encounters a - sequence of bytes that do not form a valid multibyte character, an encoding error occurs: - the mbstowcs_s function stores the value (size_t)(-1) into *retval. - Otherwise, the mbstowcs_s function stores into *retval the number of multibyte - characters successfully converted, not including the terminating null character (if any). -6 All elements following the terminating null wide character (if any) written by - mbstowcs_s in the array of dstmax wide characters pointed to by dst take - unspecified values when mbstowcs_s returns.395) -7 If copying takes place between objects that overlap, the objects take on unspecified - values. - Returns -8 The mbstowcs_s function returns zero if no runtime-constraint violation and no - encoding error occurred. Otherwise, a nonzero value is returned. - K.3.6.5.2 The wcstombs_s function - Synopsis -1 #include - errno_t wcstombs_s(size_t * restrict retval, - char * restrict dst, rsize_t dstmax, - const wchar_t * restrict src, rsize_t len); - Runtime-constraints -2 Neither retval nor src shall be a null pointer. If dst is not a null pointer, then - neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null pointer, - then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall not equal - zero. If dst is not a null pointer and len is not less than dstmax, then the conversion - shall have been stopped (see below) because a terminating null wide character was - reached or because an encoding error occurred. - - - - - 394) Thus, the value of len is ignored if dst is a null pointer. - 395) This allows an implementation to attempt converting the multibyte string before discovering a - terminating null character did not occur where required. - -[page 607] - -3 If there is a runtime-constraint violation, then wcstombs_s does the following. If - retval is not a null pointer, then wcstombs_s sets *retval to (size_t)(-1). If - dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX, - then wcstombs_s sets dst[0] to the null character. - Description -4 The wcstombs_s function converts a sequence of wide characters from the array - pointed to by src into a sequence of corresponding multibyte characters that begins in - the initial shift state. If dst is not a null pointer, the converted characters are then stored - into the array pointed to by dst. Conversion continues up to and including a terminating - null wide character, which is also stored. Conversion stops earlier in two cases: - -- when a wide character is reached that does not correspond to a valid multibyte - character; - -- (if dst is not a null pointer) when the next multibyte character would exceed the - limit of n total bytes to be stored into the array pointed to by dst. If the wide - character being converted is the null wide character, then n is the lesser of len or - dstmax. Otherwise, n is the lesser of len or dstmax-1. - If the conversion stops without converting a null wide character and dst is not a null - pointer, then a null character is stored into the array pointed to by dst immediately - following any multibyte characters already stored. Each conversion takes place as if by a - call to the wcrtomb function.396) -5 Regardless of whether dst is or is not a null pointer, if the input conversion encounters a - wide character that does not correspond to a valid multibyte character, an encoding error - occurs: the wcstombs_s function stores the value (size_t)(-1) into *retval. - Otherwise, the wcstombs_s function stores into *retval the number of bytes in the - resulting multibyte character sequence, not including the terminating null character (if - any). -6 All elements following the terminating null character (if any) written by wcstombs_s - in the array of dstmax elements pointed to by dst take unspecified values when - wcstombs_s returns.397) -7 If copying takes place between objects that overlap, the objects take on unspecified - values. - - - 396) If conversion stops because a terminating null wide character has been reached, the bytes stored - include those necessary to reach the initial shift state immediately before the null byte. However, if - the conversion stops before a terminating null wide character has been reached, the result will be null - terminated, but might not end in the initial shift state. - 397) When len is not less than dstmax, the implementation might fill the array before discovering a - runtime-constraint violation. - -[page 608] - - Returns -8 The wcstombs_s function returns zero if no runtime-constraint violation and no - encoding error occurred. Otherwise, a nonzero value is returned. - K.3.7 String handling -1 The header defines two types. -2 The types are - errno_t - which is type int; and - rsize_t - which is the type size_t. - K.3.7.1 Copying functions - K.3.7.1.1 The memcpy_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t memcpy_s(void * restrict s1, rsize_t s1max, - const void * restrict s2, rsize_t n); - Runtime-constraints -2 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. n shall not be greater than s1max. Copying shall not take place between - objects that overlap. -3 If there is a runtime-constraint violation, the memcpy_s function stores zeros in the first - s1max characters of the object pointed to by s1 if s1 is not a null pointer and s1max is - not greater than RSIZE_MAX. - Description -4 The memcpy_s function copies n characters from the object pointed to by s2 into the - object pointed to by s1. - Returns -5 The memcpy_s function returns zero if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - - - - -[page 609] - - K.3.7.1.2 The memmove_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t memmove_s(void *s1, rsize_t s1max, - const void *s2, rsize_t n); - Runtime-constraints -2 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. n shall not be greater than s1max. -3 If there is a runtime-constraint violation, the memmove_s function stores zeros in the - first s1max characters of the object pointed to by s1 if s1 is not a null pointer and - s1max is not greater than RSIZE_MAX. - Description -4 The memmove_s function copies n characters from the object pointed to by s2 into the - object pointed to by s1. This copying takes place as if the n characters from the object - pointed to by s2 are first copied into a temporary array of n characters that does not - overlap the objects pointed to by s1 or s2, and then the n characters from the temporary - array are copied into the object pointed to by s1. - Returns -5 The memmove_s function returns zero if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - K.3.7.1.3 The strcpy_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t strcpy_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2); - Runtime-constraints -2 Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX. - s1max shall not equal zero. s1max shall be greater than strnlen_s(s2, s1max). - Copying shall not take place between objects that overlap. -3 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then strcpy_s sets s1[0] to the - null character. - -[page 610] - - Description -4 The strcpy_s function copies the string pointed to by s2 (including the terminating - null character) into the array pointed to by s1. -5 All elements following the terminating null character (if any) written by strcpy_s in - the array of s1max characters pointed to by s1 take unspecified values when - strcpy_s returns.398) - Returns -6 The strcpy_s function returns zero399) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - K.3.7.1.4 The strncpy_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t strncpy_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2, - rsize_t n); - Runtime-constraints -2 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. s1max shall not equal zero. If n is not less than s1max, then s1max - shall be greater than strnlen_s(s2, s1max). Copying shall not take place between - objects that overlap. -3 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then strncpy_s sets s1[0] to the - null character. - Description -4 The strncpy_s function copies not more than n successive characters (characters that - follow a null character are not copied) from the array pointed to by s2 to the array - pointed to by s1. If no null character was copied from s2, then s1[n] is set to a null - character. - - - 398) This allows an implementation to copy characters from s2 to s1 while simultaneously checking if - any of those characters are null. Such an approach might write a character to every element of s1 - before discovering that the first element should be set to the null character. - 399) A zero return value implies that all of the requested characters from the string pointed to by s2 fit - within the array pointed to by s1 and that the result in s1 is null terminated. - -[page 611] - -5 All elements following the terminating null character (if any) written by strncpy_s in - the array of s1max characters pointed to by s1 take unspecified values when - strncpy_s returns.400) - Returns -6 The strncpy_s function returns zero401) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. -7 EXAMPLE 1 The strncpy_s function can be used to copy a string without the danger that the result - will not be null terminated or that characters will be written past the end of the destination array. - #define __STDC_WANT_LIB_EXT1__ 1 - #include - /* ... */ - char src1[100] = "hello"; - char src2[7] = {'g', 'o', 'o', 'd', 'b', 'y', 'e'}; - char dst1[6], dst2[5], dst3[5]; - int r1, r2, r3; - r1 = strncpy_s(dst1, 6, src1, 100); - r2 = strncpy_s(dst2, 5, src2, 7); - r3 = strncpy_s(dst3, 5, src2, 4); - The first call will assign to r1 the value zero and to dst1 the sequence hello\0. - The second call will assign to r2 a nonzero value and to dst2 the sequence \0. - The third call will assign to r3 the value zero and to dst3 the sequence good\0. - - K.3.7.2 Concatenation functions - K.3.7.2.1 The strcat_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t strcat_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2); - Runtime-constraints -2 Let m denote the value s1max - strnlen_s(s1, s1max) upon entry to - strcat_s. - - - - - 400) This allows an implementation to copy characters from s2 to s1 while simultaneously checking if - any of those characters are null. Such an approach might write a character to every element of s1 - before discovering that the first element should be set to the null character. - 401) A zero return value implies that all of the requested characters from the string pointed to by s2 fit - within the array pointed to by s1 and that the result in s1 is null terminated. - -[page 612] - -3 Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX. - s1max shall not equal zero. m shall not equal zero.402) m shall be greater than - strnlen_s(s2, m). Copying shall not take place between objects that overlap. -4 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then strcat_s sets s1[0] to the - null character. - Description -5 The strcat_s function appends a copy of the string pointed to by s2 (including the - terminating null character) to the end of the string pointed to by s1. The initial character - from s2 overwrites the null character at the end of s1. -6 All elements following the terminating null character (if any) written by strcat_s in - the array of s1max characters pointed to by s1 take unspecified values when - strcat_s returns.403) - Returns -7 The strcat_s function returns zero404) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - K.3.7.2.2 The strncat_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t strncat_s(char * restrict s1, - rsize_t s1max, - const char * restrict s2, - rsize_t n); - Runtime-constraints -2 Let m denote the value s1max - strnlen_s(s1, s1max) upon entry to - strncat_s. -3 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. s1max shall not equal zero. m shall not equal zero.405) If n is not less - - - 402) Zero means that s1 was not null terminated upon entry to strcat_s. - 403) This allows an implementation to append characters from s2 to s1 while simultaneously checking if - any of those characters are null. Such an approach might write a character to every element of s1 - before discovering that the first element should be set to the null character. - 404) A zero return value implies that all of the requested characters from the string pointed to by s2 were - appended to the string pointed to by s1 and that the result in s1 is null terminated. - -[page 613] - - than m, then m shall be greater than strnlen_s(s2, m). Copying shall not take - place between objects that overlap. -4 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then strncat_s sets s1[0] to the - null character. - Description -5 The strncat_s function appends not more than n successive characters (characters - that follow a null character are not copied) from the array pointed to by s2 to the end of - the string pointed to by s1. The initial character from s2 overwrites the null character at - the end of s1. If no null character was copied from s2, then s1[s1max-m+n] is set to - a null character. -6 All elements following the terminating null character (if any) written by strncat_s in - the array of s1max characters pointed to by s1 take unspecified values when - strncat_s returns.406) - Returns -7 The strncat_s function returns zero407) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. -8 EXAMPLE 1 The strncat_s function can be used to copy a string without the danger that the result - will not be null terminated or that characters will be written past the end of the destination array. - #define __STDC_WANT_LIB_EXT1__ 1 - #include - /* ... */ - char s1[100] = "good"; - char s2[6] = "hello"; - char s3[6] = "hello"; - char s4[7] = "abc"; - char s5[1000] = "bye"; - int r1, r2, r3, r4; - r1 = strncat_s(s1, 100, s5, 1000); - r2 = strncat_s(s2, 6, "", 1); - r3 = strncat_s(s3, 6, "X", 2); - r4 = strncat_s(s4, 7, "defghijklmn", 3); - After the first call r1 will have the value zero and s1 will contain the sequence goodbye\0. - - - - 405) Zero means that s1 was not null terminated upon entry to strncat_s. - 406) This allows an implementation to append characters from s2 to s1 while simultaneously checking if - any of those characters are null. Such an approach might write a character to every element of s1 - before discovering that the first element should be set to the null character. - 407) A zero return value implies that all of the requested characters from the string pointed to by s2 were - appended to the string pointed to by s1 and that the result in s1 is null terminated. - -[page 614] - - After the second call r2 will have the value zero and s2 will contain the sequence hello\0. - After the third call r3 will have a nonzero value and s3 will contain the sequence \0. - After the fourth call r4 will have the value zero and s4 will contain the sequence abcdef\0. - - K.3.7.3 Search functions - K.3.7.3.1 The strtok_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - char *strtok_s(char * restrict s1, - rsize_t * restrict s1max, - const char * restrict s2, - char ** restrict ptr); - Runtime-constraints -2 None of s1max, s2, or ptr shall be a null pointer. If s1 is a null pointer, then *ptr - shall not be a null pointer. The value of *s1max shall not be greater than RSIZE_MAX. - The end of the token found shall occur within the first *s1max characters of s1 for the - first call, and shall occur within the first *s1max characters of where searching resumes - on subsequent calls. -3 If there is a runtime-constraint violation, the strtok_s function does not indirect - through the s1 or s2 pointers, and does not store a value in the object pointed to by ptr. - Description -4 A sequence of calls to the strtok_s function breaks the string pointed to by s1 into a - sequence of tokens, each of which is delimited by a character from the string pointed to - by s2. The fourth argument points to a caller-provided char pointer into which the - strtok_s function stores information necessary for it to continue scanning the same - string. -5 The first call in a sequence has a non-null first argument and s1max points to an object - whose value is the number of elements in the character array pointed to by the first - argument. The first call stores an initial value in the object pointed to by ptr and - updates the value pointed to by s1max to reflect the number of elements that remain in - relation to ptr. Subsequent calls in the sequence have a null first argument and the - objects pointed to by s1max and ptr are required to have the values stored by the - previous call in the sequence, which are then updated. The separator string pointed to by - s2 may be different from call to call. -6 The first call in the sequence searches the string pointed to by s1 for the first character - that is not contained in the current separator string pointed to by s2. If no such character - is found, then there are no tokens in the string pointed to by s1 and the strtok_s - function returns a null pointer. If such a character is found, it is the start of the first token. -[page 615] - -7 The strtok_s function then searches from there for the first character in s1 that is - contained in the current separator string. If no such character is found, the current token - extends to the end of the string pointed to by s1, and subsequent searches in the same - string for a token return a null pointer. If such a character is found, it is overwritten by a - null character, which terminates the current token. -8 In all cases, the strtok_s function stores sufficient information in the pointer pointed - to by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer - value for ptr, shall start searching just past the element overwritten by a null character - (if any). - Returns -9 The strtok_s function returns a pointer to the first character of a token, or a null - pointer if there is no token or there is a runtime-constraint violation. -10 EXAMPLE - #define __STDC_WANT_LIB_EXT1__ 1 - #include - static char str1[] = "?a???b,,,#c"; - static char str2[] = "\t \t"; - char *t, *ptr1, *ptr2; - rsize_t max1 = sizeof(str1); - rsize_t max2 = sizeof(str2); - t = strtok_s(str1, &max1, "?", &ptr1); // t points to the token "a" - t = strtok_s(NULL, &max1, ",", &ptr1); // t points to the token "??b" - t = strtok_s(str2, &max2, " \t", &ptr2); // t is a null pointer - t = strtok_s(NULL, &max1, "#,", &ptr1); // t points to the token "c" - t = strtok_s(NULL, &max1, "?", &ptr1); // t is a null pointer - - K.3.7.4 Miscellaneous functions - K.3.7.4.1 The memset_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t memset_s(void *s, rsize_t smax, int c, rsize_t n) - Runtime-constraints -2 s shall not be a null pointer. Neither smax nor n shall be greater than RSIZE_MAX. n - shall not be greater than smax. -3 If there is a runtime-constraint violation, then if s is not a null pointer and smax is not - greater than RSIZE_MAX, the memset_s function stores the value of c (converted to an - unsigned char) into each of the first smax characters of the object pointed to by s. - - - -[page 616] - - Description -4 The memset_s function copies the value of c (converted to an unsigned char) into - each of the first n characters of the object pointed to by s. Unlike memset, any call to - the memset_s function shall be evaluated strictly according to the rules of the abstract - machine as described in (5.1.2.3). That is, any call to the memset_s function shall - assume that the memory indicated by s and n may be accessible in the future and thus - must contain the values indicated by c. - Returns -5 The memset_s function returns zero if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - K.3.7.4.2 The strerror_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t strerror_s(char *s, rsize_t maxsize, - errno_t errnum); - Runtime-constraints -2 s shall not be a null pointer. maxsize shall not be greater than RSIZE_MAX. - maxsize shall not equal zero. -3 If there is a runtime-constraint violation, then the array (if any) pointed to by s is not - modified. - Description -4 The strerror_s function maps the number in errnum to a locale-specific message - string. Typically, the values for errnum come from errno, but strerror_s shall - map any value of type int to a message. -5 If the length of the desired string is less than maxsize, then the string is copied to the - array pointed to by s. -6 Otherwise, if maxsize is greater than zero, then maxsize-1 characters are copied - from the string to the array pointed to by s and then s[maxsize-1] is set to the null - character. Then, if maxsize is greater than 3, then s[maxsize-2], - s[maxsize-3], and s[maxsize-4] are set to the character period (.). - Returns -7 The strerror_s function returns zero if the length of the desired string was less than - maxsize and there was no runtime-constraint violation. Otherwise, the strerror_s - function returns a nonzero value. - -[page 617] - - K.3.7.4.3 The strerrorlen_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - size_t strerrorlen_s(errno_t errnum); - Description -2 The strerrorlen_s function calculates the length of the (untruncated) locale-specific - message string that the strerror_s function maps to errnum. - Returns -3 The strerrorlen_s function returns the number of characters (not including the null - character) in the full message string. - K.3.7.4.4 The strnlen_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - size_t strnlen_s(const char *s, size_t maxsize); - Description -2 The strnlen_s function computes the length of the string pointed to by s. - Returns -3 If s is a null pointer,408) then the strnlen_s function returns zero. -4 Otherwise, the strnlen_s function returns the number of characters that precede the - terminating null character. If there is no null character in the first maxsize characters of - s then strnlen_s returns maxsize. At most the first maxsize characters of s shall - be accessed by strnlen_s. - - - - - 408) Note that the strnlen_s function has no runtime-constraints. This lack of runtime-constraints - along with the values returned for a null pointer or an unterminated string argument make - strnlen_s useful in algorithms that gracefully handle such exceptional data. - -[page 618] - - K.3.8 Date and time -1 The header defines two types. -2 The types are - errno_t - which is type int; and - rsize_t - which is the type size_t. - K.3.8.1 Components of time -1 A broken-down time is normalized if the values of the members of the tm structure are in - their normal rages.409) - K.3.8.2 Time conversion functions -1 Like the strftime function, the asctime_s and ctime_s functions do not return a - pointer to a static object, and other library functions are permitted to call them. - K.3.8.2.1 The asctime_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t asctime_s(char *s, rsize_t maxsize, - const struct tm *timeptr); - Runtime-constraints -2 Neither s nor timeptr shall be a null pointer. maxsize shall not be less than 26 and - shall not be greater than RSIZE_MAX. The broken-down time pointed to by timeptr - shall be normalized. The calendar year represented by the broken-down time pointed to - by timeptr shall not be less than calendar year 0 and shall not be greater than calendar - year 9999. -3 If there is a runtime-constraint violation, there is no attempt to convert the time, and - s[0] is set to a null character if s is not a null pointer and maxsize is not zero and is - not greater than RSIZE_MAX. - Description -4 The asctime_s function converts the normalized broken-down time in the structure - pointed to by timeptr into a 26 character (including the null character) string in the - - - 409) The normal ranges are defined in 7.26.1. - -[page 619] - - form - Sun Sep 16 01:03:52 1973\n\0 - The fields making up this string are (in order): - 1. The name of the day of the week represented by timeptr->tm_wday using the - following three character weekday names: Sun, Mon, Tue, Wed, Thu, Fri, and Sat. - 2. The character space. - 3. The name of the month represented by timeptr->tm_mon using the following - three character month names: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, - Nov, and Dec. - 4. The character space. - 5. The value of timeptr->tm_mday as if printed using the fprintf format - "%2d". - 6. The character space. - 7. The value of timeptr->tm_hour as if printed using the fprintf format - "%.2d". - 8. The character colon. - 9. The value of timeptr->tm_min as if printed using the fprintf format - "%.2d". - 10. The character colon. - 11. The value of timeptr->tm_sec as if printed using the fprintf format - "%.2d". - 12. The character space. - 13. The value of timeptr->tm_year + 1900 as if printed using the fprintf - format "%4d". - 14. The character new line. - 15. The null character. - Recommended practice - The strftime function allows more flexible formatting and supports locale-specific - behavior. If you do not require the exact form of the result string produced by the - asctime_s function, consider using the strftime function instead. - Returns -5 The asctime_s function returns zero if the time was successfully converted and stored - into the array pointed to by s. Otherwise, it returns a nonzero value. -[page 620] - - K.3.8.2.2 The ctime_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t ctime_s(char *s, rsize_t maxsize, - const time_t *timer); - Runtime-constraints -2 Neither s nor timer shall be a null pointer. maxsize shall not be less than 26 and - shall not be greater than RSIZE_MAX. -3 If there is a runtime-constraint violation, s[0] is set to a null character if s is not a null - pointer and maxsize is not equal zero and is not greater than RSIZE_MAX. - Description -4 The ctime_s function converts the calendar time pointed to by timer to local time in - the form of a string. It is equivalent to - asctime_s(s, maxsize, localtime_s(timer)) - Recommended practice - The strftime function allows more flexible formatting and supports locale-specific - behavior. If you do not require the exact form of the result string produced by the - ctime_s function, consider using the strftime function instead. - Returns -5 The ctime_s function returns zero if the time was successfully converted and stored - into the array pointed to by s. Otherwise, it returns a nonzero value. - K.3.8.2.3 The gmtime_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - struct tm *gmtime_s(const time_t * restrict timer, - struct tm * restrict result); - Runtime-constraints -2 Neither timer nor result shall be a null pointer. -3 If there is a runtime-constraint violation, there is no attempt to convert the time. - Description -4 The gmtime_s function converts the calendar time pointed to by timer into a broken- - down time, expressed as UTC. The broken-down time is stored in the structure pointed -[page 621] - - to by result. - Returns -5 The gmtime_s function returns result, or a null pointer if the specified time cannot - be converted to UTC or there is a runtime-constraint violation. - K.3.8.2.4 The localtime_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - struct tm *localtime_s(const time_t * restrict timer, - struct tm * restrict result); - Runtime-constraints -2 Neither timer nor result shall be a null pointer. -3 If there is a runtime-constraint violation, there is no attempt to convert the time. - Description -4 The localtime_s function converts the calendar time pointed to by timer into a - broken-down time, expressed as local time. The broken-down time is stored in the - structure pointed to by result. - Returns -5 The localtime_s function returns result, or a null pointer if the specified time - cannot be converted to local time or there is a runtime-constraint violation. - K.3.9 Extended multibyte and wide character utilities -1 The header defines two types. -2 The types are - errno_t - which is type int; and - rsize_t - which is the type size_t. -3 Unless explicitly stated otherwise, if the execution of a function described in this - subclause causes copying to take place between objects that overlap, the objects take on - unspecified values. - - - - -[page 622] - - K.3.9.1 Formatted wide character input/output functions - K.3.9.1.1 The fwprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int fwprintf_s(FILE * restrict stream, - const wchar_t * restrict format, ...); - Runtime-constraints -2 Neither stream nor format shall be a null pointer. The %n specifier410) (modified or - not by flags, field width, or precision) shall not appear in the wide string pointed to by - format. Any argument to fwprintf_s corresponding to a %s specifier shall not be a - null pointer. -3 If there is a runtime-constraint violation, the fwprintf_s function does not attempt to - produce further output, and it is unspecified to what extent fwprintf_s produced - output before discovering the runtime-constraint violation. - Description -4 The fwprintf_s function is equivalent to the fwprintf function except for the - explicit runtime-constraints listed above. - Returns -5 The fwprintf_s function returns the number of wide characters transmitted, or a - negative value if an output error, encoding error, or runtime-constraint violation occurred. - K.3.9.1.2 The fwscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int fwscanf_s(FILE * restrict stream, - const wchar_t * restrict format, ...); - Runtime-constraints -2 Neither stream nor format shall be a null pointer. Any argument indirected though in - order to store converted input shall not be a null pointer. - - - 410) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 623] - -3 If there is a runtime-constraint violation, the fwscanf_s function does not attempt to - perform further input, and it is unspecified to what extent fwscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The fwscanf_s function is equivalent to fwscanf except that the c, s, and [ - conversion specifiers apply to a pair of arguments (unless assignment suppression is - indicated by a *). The first of these arguments is the same as for fwscanf. That - argument is immediately followed in the argument list by the second argument, which has - type size_t and gives the number of elements in the array pointed to by the first - argument of the pair. If the first argument points to a scalar object, it is considered to be - an array of one element.411) -5 A matching failure occurs if the number of elements in a receiving object is insufficient to - hold the converted input (including any trailing null character). - Returns -6 The fwscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - fwscanf_s function returns the number of input items assigned, which can be fewer - than provided for, or even zero, in the event of an early matching failure. - K.3.9.1.3 The snwprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int snwprintf_s(wchar_t * restrict s, - rsize_t n, - const wchar_t * restrict format, ...); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The %n specifier412) (modified or not by flags, field width, or - - 411) If the format is known at translation time, an implementation may issue a diagnostic for any argument - used to store the result from a c, s, or [ conversion specifier if that argument is not followed by an - argument of a type compatible with rsize_t. A limited amount of checking may be done if even if - the format is not known at translation time. For example, an implementation may issue a diagnostic - for each argument after format that has of type pointer to one of char, signed char, - unsigned char, or void that is not followed by an argument of a type compatible with - rsize_t. The diagnostic could warn that unless the pointer is being used with a conversion specifier - using the hh length modifier, a length argument must follow the pointer argument. Another useful - diagnostic could flag any non-pointer argument following format that did not have a type - compatible with rsize_t. - -[page 624] - - precision) shall not appear in the wide string pointed to by format. Any argument to - snwprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding - error shall occur. -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the snwprintf_s function sets s[0] to the - null wide character. - Description -4 The snwprintf_s function is equivalent to the swprintf function except for the - explicit runtime-constraints listed above. -5 The snwprintf_s function, unlike swprintf_s, will truncate the result to fit within - the array pointed to by s. - Returns -6 The snwprintf_s function returns the number of wide characters that would have - been written had n been sufficiently large, not counting the terminating wide null - character, or a negative value if a runtime-constraint violation occurred. Thus, the null- - terminated output has been completely written if and only if the returned value is - nonnegative and less than n. - K.3.9.1.4 The swprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int swprintf_s(wchar_t * restrict s, rsize_t n, - const wchar_t * restrict format, ...); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The number of wide characters (including the trailing null) required - for the result to be written to the array pointed to by s shall not be greater than n. The %n - specifier413) (modified or not by flags, field width, or precision) shall not appear in the - wide string pointed to by format. Any argument to swprintf_s corresponding to a - %s specifier shall not be a null pointer. No encoding error shall occur. - - - 412) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - 413) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 625] - -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the swprintf_s function sets s[0] to the - null wide character. - Description -4 The swprintf_s function is equivalent to the swprintf function except for the - explicit runtime-constraints listed above. -5 The swprintf_s function, unlike snwprintf_s, treats a result too big for the array - pointed to by s as a runtime-constraint violation. - Returns -6 If no runtime-constraint violation occurred, the swprintf_s function returns the - number of wide characters written in the array, not counting the terminating null wide - character. If an encoding error occurred or if n or more wide characters are requested to - be written, swprintf_s returns a negative value. If any other runtime-constraint - violation occurred, swprintf_s returns zero. - K.3.9.1.5 The swscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int swscanf_s(const wchar_t * restrict s, - const wchar_t * restrict format, ...); - Runtime-constraints -2 Neither s nor format shall be a null pointer. Any argument indirected though in order - to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the swscanf_s function does not attempt to - perform further input, and it is unspecified to what extent swscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The swscanf_s function is equivalent to fwscanf_s, except that the argument s - specifies a wide string from which the input is to be obtained, rather than from a stream. - Reaching the end of the wide string is equivalent to encountering end-of-file for the - fwscanf_s function. - Returns -5 The swscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - swscanf_s function returns the number of input items assigned, which can be fewer - than provided for, or even zero, in the event of an early matching failure. -[page 626] - - K.3.9.1.6 The vfwprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - #include - int vfwprintf_s(FILE * restrict stream, - const wchar_t * restrict format, - va_list arg); - Runtime-constraints -2 Neither stream nor format shall be a null pointer. The %n specifier414) (modified or - not by flags, field width, or precision) shall not appear in the wide string pointed to by - format. Any argument to vfwprintf_s corresponding to a %s specifier shall not be - a null pointer. -3 If there is a runtime-constraint violation, the vfwprintf_s function does not attempt - to produce further output, and it is unspecified to what extent vfwprintf_s produced - output before discovering the runtime-constraint violation. - Description -4 The vfwprintf_s function is equivalent to the vfwprintf function except for the - explicit runtime-constraints listed above. - Returns -5 The vfwprintf_s function returns the number of wide characters transmitted, or a - negative value if an output error, encoding error, or runtime-constraint violation occurred. - K.3.9.1.7 The vfwscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - #include - int vfwscanf_s(FILE * restrict stream, - const wchar_t * restrict format, va_list arg); - - - - 414) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 627] - - Runtime-constraints -2 Neither stream nor format shall be a null pointer. Any argument indirected though in - order to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the vfwscanf_s function does not attempt to - perform further input, and it is unspecified to what extent vfwscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The vfwscanf_s function is equivalent to fwscanf_s, with the variable argument - list replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vfwscanf_s function does not invoke the - va_end macro.415) - Returns -5 The vfwscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - vfwscanf_s function returns the number of input items assigned, which can be fewer - than provided for, or even zero, in the event of an early matching failure. - K.3.9.1.8 The vsnwprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vsnwprintf_s(wchar_t * restrict s, - rsize_t n, - const wchar_t * restrict format, - va_list arg); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The %n specifier416) (modified or not by flags, field width, or - precision) shall not appear in the wide string pointed to by format. Any argument to - vsnwprintf_s corresponding to a %s specifier shall not be a null pointer. No - encoding error shall occur. - - 415) As the functions vfwscanf_s, vwscanf_s, and vswscanf_s invoke the va_arg macro, the - value of arg after the return is indeterminate. - 416) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 628] - -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the vsnwprintf_s function sets s[0] to - the null wide character. - Description -4 The vsnwprintf_s function is equivalent to the vswprintf function except for the - explicit runtime-constraints listed above. -5 The vsnwprintf_s function, unlike vswprintf_s, will truncate the result to fit - within the array pointed to by s. - Returns -6 The vsnwprintf_s function returns the number of wide characters that would have - been written had n been sufficiently large, not counting the terminating null character, or - a negative value if a runtime-constraint violation occurred. Thus, the null-terminated - output has been completely written if and only if the returned value is nonnegative and - less than n. - K.3.9.1.9 The vswprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vswprintf_s(wchar_t * restrict s, - rsize_t n, - const wchar_t * restrict format, - va_list arg); - Runtime-constraints -2 Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater - than RSIZE_MAX. The number of wide characters (including the trailing null) required - for the result to be written to the array pointed to by s shall not be greater than n. The %n - specifier417) (modified or not by flags, field width, or precision) shall not appear in the - wide string pointed to by format. Any argument to vswprintf_s corresponding to a - %s specifier shall not be a null pointer. No encoding error shall occur. -3 If there is a runtime-constraint violation, then if s is not a null pointer and n is greater - than zero and less than RSIZE_MAX, then the vswprintf_s function sets s[0] to the - null wide character. - - 417) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 629] - - Description -4 The vswprintf_s function is equivalent to the vswprintf function except for the - explicit runtime-constraints listed above. -5 The vswprintf_s function, unlike vsnwprintf_s, treats a result too big for the - array pointed to by s as a runtime-constraint violation. - Returns -6 If no runtime-constraint violation occurred, the vswprintf_s function returns the - number of wide characters written in the array, not counting the terminating null wide - character. If an encoding error occurred or if n or more wide characters are requested to - be written, vswprintf_s returns a negative value. If any other runtime-constraint - violation occurred, vswprintf_s returns zero. - K.3.9.1.10 The vswscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vswscanf_s(const wchar_t * restrict s, - const wchar_t * restrict format, - va_list arg); - Runtime-constraints -2 Neither s nor format shall be a null pointer. Any argument indirected though in order - to store converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the vswscanf_s function does not attempt to - perform further input, and it is unspecified to what extent vswscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The vswscanf_s function is equivalent to swscanf_s, with the variable argument - list replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vswscanf_s function does not invoke the - va_end macro.418) - - - - - 418) As the functions vfwscanf_s, vwscanf_s, and vswscanf_s invoke the va_arg macro, the - value of arg after the return is indeterminate. - -[page 630] - - Returns -5 The vswscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - vswscanf_s function returns the number of input items assigned, which can be fewer - than provided for, or even zero, in the event of an early matching failure. - K.3.9.1.11 The vwprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vwprintf_s(const wchar_t * restrict format, - va_list arg); - Runtime-constraints -2 format shall not be a null pointer. The %n specifier419) (modified or not by flags, field - width, or precision) shall not appear in the wide string pointed to by format. Any - argument to vwprintf_s corresponding to a %s specifier shall not be a null pointer. -3 If there is a runtime-constraint violation, the vwprintf_s function does not attempt to - produce further output, and it is unspecified to what extent vwprintf_s produced - output before discovering the runtime-constraint violation. - Description -4 The vwprintf_s function is equivalent to the vwprintf function except for the - explicit runtime-constraints listed above. - Returns -5 The vwprintf_s function returns the number of wide characters transmitted, or a - negative value if an output error, encoding error, or runtime-constraint violation occurred. - - - - - 419) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 631] - - K.3.9.1.12 The vwscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - #include - int vwscanf_s(const wchar_t * restrict format, - va_list arg); - Runtime-constraints -2 format shall not be a null pointer. Any argument indirected though in order to store - converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the vwscanf_s function does not attempt to - perform further input, and it is unspecified to what extent vwscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The vwscanf_s function is equivalent to wscanf_s, with the variable argument list - replaced by arg, which shall have been initialized by the va_start macro (and - possibly subsequent va_arg calls). The vwscanf_s function does not invoke the - va_end macro.420) - Returns -5 The vwscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - vwscanf_s function returns the number of input items assigned, which can be fewer - than provided for, or even zero, in the event of an early matching failure. - K.3.9.1.13 The wprintf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int wprintf_s(const wchar_t * restrict format, ...); - Runtime-constraints -2 format shall not be a null pointer. The %n specifier421) (modified or not by flags, field - - 420) As the functions vfwscanf_s, vwscanf_s, and vswscanf_s invoke the va_arg macro, the - value of arg after the return is indeterminate. - 421) It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide - string pointed at by format when those wide characters are not a interpreted as a %n specifier. For - example, if the entire format string was L"%%n". - -[page 632] - - width, or precision) shall not appear in the wide string pointed to by format. Any - argument to wprintf_s corresponding to a %s specifier shall not be a null pointer. -3 If there is a runtime-constraint violation, the wprintf_s function does not attempt to - produce further output, and it is unspecified to what extent wprintf_s produced output - before discovering the runtime-constraint violation. - Description -4 The wprintf_s function is equivalent to the wprintf function except for the explicit - runtime-constraints listed above. - Returns -5 The wprintf_s function returns the number of wide characters transmitted, or a - negative value if an output error, encoding error, or runtime-constraint violation occurred. - K.3.9.1.14 The wscanf_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - int wscanf_s(const wchar_t * restrict format, ...); - Runtime-constraints -2 format shall not be a null pointer. Any argument indirected though in order to store - converted input shall not be a null pointer. -3 If there is a runtime-constraint violation, the wscanf_s function does not attempt to - perform further input, and it is unspecified to what extent wscanf_s performed input - before discovering the runtime-constraint violation. - Description -4 The wscanf_s function is equivalent to fwscanf_s with the argument stdin - interposed before the arguments to wscanf_s. - Returns -5 The wscanf_s function returns the value of the macro EOF if an input failure occurs - before any conversion or if there is a runtime-constraint violation. Otherwise, the - wscanf_s function returns the number of input items assigned, which can be fewer than - provided for, or even zero, in the event of an early matching failure. - - - - -[page 633] - - K.3.9.2 General wide string utilities - K.3.9.2.1 Wide string copying functions - K.3.9.2.1.1 The wcscpy_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wcscpy_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2); - Runtime-constraints -2 Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX. - s1max shall not equal zero. s1max shall be greater than wcsnlen_s(s2, s1max). - Copying shall not take place between objects that overlap. -3 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then wcscpy_s sets s1[0] to the - null wide character. - Description -4 The wcscpy_s function copies the wide string pointed to by s2 (including the - terminating null wide character) into the array pointed to by s1. -5 All elements following the terminating null wide character (if any) written by - wcscpy_s in the array of s1max wide characters pointed to by s1 take unspecified - values when wcscpy_s returns.422) - Returns -6 The wcscpy_s function returns zero423) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - - - - - 422) This allows an implementation to copy wide characters from s2 to s1 while simultaneously checking - if any of those wide characters are null. Such an approach might write a wide character to every - element of s1 before discovering that the first element should be set to the null wide character. - 423) A zero return value implies that all of the requested wide characters from the string pointed to by s2 - fit within the array pointed to by s1 and that the result in s1 is null terminated. - -[page 634] - - K.3.9.2.1.2 The wcsncpy_s function - Synopsis -7 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wcsncpy_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2, - rsize_t n); - Runtime-constraints -8 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. s1max shall not equal zero. If n is not less than s1max, then s1max - shall be greater than wcsnlen_s(s2, s1max). Copying shall not take place between - objects that overlap. -9 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then wcsncpy_s sets s1[0] to the - null wide character. - Description -10 The wcsncpy_s function copies not more than n successive wide characters (wide - characters that follow a null wide character are not copied) from the array pointed to by - s2 to the array pointed to by s1. If no null wide character was copied from s2, then - s1[n] is set to a null wide character. -11 All elements following the terminating null wide character (if any) written by - wcsncpy_s in the array of s1max wide characters pointed to by s1 take unspecified - values when wcsncpy_s returns.424) - Returns -12 The wcsncpy_s function returns zero425) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. -13 EXAMPLE 1 The wcsncpy_s function can be used to copy a wide string without the danger that the - result will not be null terminated or that wide characters will be written past the end of the destination - array. - - - - - 424) This allows an implementation to copy wide characters from s2 to s1 while simultaneously checking - if any of those wide characters are null. Such an approach might write a wide character to every - element of s1 before discovering that the first element should be set to the null wide character. - 425) A zero return value implies that all of the requested wide characters from the string pointed to by s2 - fit within the array pointed to by s1 and that the result in s1 is null terminated. - -[page 635] - - #define __STDC_WANT_LIB_EXT1__ 1 - #include - /* ... */ - wchar_t src1[100] = L"hello"; - wchar_t src2[7] = {L'g', L'o', L'o', L'd', L'b', L'y', L'e'}; - wchar_t dst1[6], dst2[5], dst3[5]; - int r1, r2, r3; - r1 = wcsncpy_s(dst1, 6, src1, 100); - r2 = wcsncpy_s(dst2, 5, src2, 7); - r3 = wcsncpy_s(dst3, 5, src2, 4); - The first call will assign to r1 the value zero and to dst1 the sequence of wide characters hello\0. - The second call will assign to r2 a nonzero value and to dst2 the sequence of wide characters \0. - The third call will assign to r3 the value zero and to dst3 the sequence of wide characters good\0. - - K.3.9.2.1.3 The wmemcpy_s function - Synopsis -14 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wmemcpy_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2, - rsize_t n); - Runtime-constraints -15 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. n shall not be greater than s1max. Copying shall not take place between - objects that overlap. -16 If there is a runtime-constraint violation, the wmemcpy_s function stores zeros in the - first s1max wide characters of the object pointed to by s1 if s1 is not a null pointer and - s1max is not greater than RSIZE_MAX. - Description -17 The wmemcpy_s function copies n successive wide characters from the object pointed - to by s2 into the object pointed to by s1. - Returns -18 The wmemcpy_s function returns zero if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - - - - -[page 636] - - K.3.9.2.1.4 The wmemmove_s function - Synopsis -19 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wmemmove_s(wchar_t *s1, rsize_t s1max, - const wchar_t *s2, rsize_t n); - Runtime-constraints -20 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. n shall not be greater than s1max. -21 If there is a runtime-constraint violation, the wmemmove_s function stores zeros in the - first s1max wide characters of the object pointed to by s1 if s1 is not a null pointer and - s1max is not greater than RSIZE_MAX. - Description -22 The wmemmove_s function copies n successive wide characters from the object pointed - to by s2 into the object pointed to by s1. This copying takes place as if the n wide - characters from the object pointed to by s2 are first copied into a temporary array of n - wide characters that does not overlap the objects pointed to by s1 or s2, and then the n - wide characters from the temporary array are copied into the object pointed to by s1. - Returns -23 The wmemmove_s function returns zero if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - K.3.9.2.2 Wide string concatenation functions - K.3.9.2.2.1 The wcscat_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wcscat_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2); - Runtime-constraints -2 Let m denote the value s1max - wcsnlen_s(s1, s1max) upon entry to - wcscat_s. -3 Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX. - s1max shall not equal zero. m shall not equal zero.426) m shall be greater than - wcsnlen_s(s2, m). Copying shall not take place between objects that overlap. - -[page 637] - -4 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then wcscat_s sets s1[0] to the - null wide character. - Description -5 The wcscat_s function appends a copy of the wide string pointed to by s2 (including - the terminating null wide character) to the end of the wide string pointed to by s1. The - initial wide character from s2 overwrites the null wide character at the end of s1. -6 All elements following the terminating null wide character (if any) written by - wcscat_s in the array of s1max wide characters pointed to by s1 take unspecified - values when wcscat_s returns.427) - Returns -7 The wcscat_s function returns zero428) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. - K.3.9.2.2.2 The wcsncat_s function - Synopsis -8 #define __STDC_WANT_LIB_EXT1__ 1 - #include - errno_t wcsncat_s(wchar_t * restrict s1, - rsize_t s1max, - const wchar_t * restrict s2, - rsize_t n); - Runtime-constraints -9 Let m denote the value s1max - wcsnlen_s(s1, s1max) upon entry to - wcsncat_s. -10 Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than - RSIZE_MAX. s1max shall not equal zero. m shall not equal zero.429) If n is not less - than m, then m shall be greater than wcsnlen_s(s2, m). Copying shall not take - place between objects that overlap. - - - 426) Zero means that s1 was not null terminated upon entry to wcscat_s. - 427) This allows an implementation to append wide characters from s2 to s1 while simultaneously - checking if any of those wide characters are null. Such an approach might write a wide character to - every element of s1 before discovering that the first element should be set to the null wide character. - 428) A zero return value implies that all of the requested wide characters from the wide string pointed to by - s2 were appended to the wide string pointed to by s1 and that the result in s1 is null terminated. - 429) Zero means that s1 was not null terminated upon entry to wcsncat_s. - -[page 638] - -11 If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is - greater than zero and not greater than RSIZE_MAX, then wcsncat_s sets s1[0] to the - null wide character. - Description -12 The wcsncat_s function appends not more than n successive wide characters (wide - characters that follow a null wide character are not copied) from the array pointed to by - s2 to the end of the wide string pointed to by s1. The initial wide character from s2 - overwrites the null wide character at the end of s1. If no null wide character was copied - from s2, then s1[s1max-m+n] is set to a null wide character. -13 All elements following the terminating null wide character (if any) written by - wcsncat_s in the array of s1max wide characters pointed to by s1 take unspecified - values when wcsncat_s returns.430) - Returns -14 The wcsncat_s function returns zero431) if there was no runtime-constraint violation. - Otherwise, a nonzero value is returned. -15 EXAMPLE 1 The wcsncat_s function can be used to copy a wide string without the danger that the - result will not be null terminated or that wide characters will be written past the end of the destination - array. - #define __STDC_WANT_LIB_EXT1__ 1 - #include - /* ... */ - wchar_t s1[100] = L"good"; - wchar_t s2[6] = L"hello"; - wchar_t s3[6] = L"hello"; - wchar_t s4[7] = L"abc"; - wchar_t s5[1000] = L"bye"; - int r1, r2, r3, r4; - r1 = wcsncat_s(s1, 100, s5, 1000); - r2 = wcsncat_s(s2, 6, L"", 1); - r3 = wcsncat_s(s3, 6, L"X", 2); - r4 = wcsncat_s(s4, 7, L"defghijklmn", 3); - After the first call r1 will have the value zero and s1 will be the wide character sequence goodbye\0. - After the second call r2 will have the value zero and s2 will be the wide character sequence hello\0. - After the third call r3 will have a nonzero value and s3 will be the wide character sequence \0. - After the fourth call r4 will have the value zero and s4 will be the wide character sequence abcdef\0. - - - - - 430) This allows an implementation to append wide characters from s2 to s1 while simultaneously - checking if any of those wide characters are null. Such an approach might write a wide character to - every element of s1 before discovering that the first element should be set to the null wide character. - 431) A zero return value implies that all of the requested wide characters from the wide string pointed to by - s2 were appended to the wide string pointed to by s1 and that the result in s1 is null terminated. - -[page 639] - - K.3.9.2.3 Wide string search functions - K.3.9.2.3.1 The wcstok_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - wchar_t *wcstok_s(wchar_t * restrict s1, - rsize_t * restrict s1max, - const wchar_t * restrict s2, - wchar_t ** restrict ptr); - Runtime-constraints -2 None of s1max, s2, or ptr shall be a null pointer. If s1 is a null pointer, then *ptr - shall not be a null pointer. The value of *s1max shall not be greater than RSIZE_MAX. - The end of the token found shall occur within the first *s1max wide characters of s1 for - the first call, and shall occur within the first *s1max wide characters of where searching - resumes on subsequent calls. -3 If there is a runtime-constraint violation, the wcstok_s function does not indirect - through the s1 or s2 pointers, and does not store a value in the object pointed to by ptr. - Description -4 A sequence of calls to the wcstok_s function breaks the wide string pointed to by s1 - into a sequence of tokens, each of which is delimited by a wide character from the wide - string pointed to by s2. The fourth argument points to a caller-provided wchar_t - pointer into which the wcstok_s function stores information necessary for it to - continue scanning the same wide string. -5 The first call in a sequence has a non-null first argument and s1max points to an object - whose value is the number of elements in the wide character array pointed to by the first - argument. The first call stores an initial value in the object pointed to by ptr and - updates the value pointed to by s1max to reflect the number of elements that remain in - relation to ptr. Subsequent calls in the sequence have a null first argument and the - objects pointed to by s1max and ptr are required to have the values stored by the - previous call in the sequence, which are then updated. The separator wide string pointed - to by s2 may be different from call to call. -6 The first call in the sequence searches the wide string pointed to by s1 for the first wide - character that is not contained in the current separator wide string pointed to by s2. If no - such wide character is found, then there are no tokens in the wide string pointed to by s1 - and the wcstok_s function returns a null pointer. If such a wide character is found, it is - the start of the first token. - - -[page 640] - -7 The wcstok_s function then searches from there for the first wide character in s1 that - is contained in the current separator wide string. If no such wide character is found, the - current token extends to the end of the wide string pointed to by s1, and subsequent - searches in the same wide string for a token return a null pointer. If such a wide character - is found, it is overwritten by a null wide character, which terminates the current token. -8 In all cases, the wcstok_s function stores sufficient information in the pointer pointed - to by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer - value for ptr, shall start searching just past the element overwritten by a null wide - character (if any). - Returns -9 The wcstok_s function returns a pointer to the first wide character of a token, or a null - pointer if there is no token or there is a runtime-constraint violation. -10 EXAMPLE - #define __STDC_WANT_LIB_EXT1__ 1 - #include - static wchar_t str1[] = L"?a???b,,,#c"; - static wchar_t str2[] = L"\t \t"; - wchar_t *t, *ptr1, *ptr2; - rsize_t max1 = wcslen(str1)+1; - rsize_t max2 = wcslen(str2)+1; - t = wcstok_s(str1, &max1, "?", &ptr1); // t points to the token "a" - t = wcstok_s(NULL, &max1, ",", &ptr1); // t points to the token "??b" - t = wcstok_s(str2, &max2, " \t", &ptr2); // t is a null pointer - t = wcstok_s(NULL, &max1, "#,", &ptr1); // t points to the token "c" - t = wcstok_s(NULL, &max1, "?", &ptr1); // t is a null pointer - - K.3.9.2.4 Miscellaneous functions - K.3.9.2.4.1 The wcsnlen_s function - Synopsis -1 #define __STDC_WANT_LIB_EXT1__ 1 - #include - size_t wcsnlen_s(const wchar_t *s, size_t maxsize); - Description -2 The wcsnlen_s function computes the length of the wide string pointed to by s. - Returns -3 If s is a null pointer,432) then the wcsnlen_s function returns zero. -4 Otherwise, the wcsnlen_s function returns the number of wide characters that precede - the terminating null wide character. If there is no null wide character in the first - maxsize wide characters of s then wcsnlen_s returns maxsize. At most the first - -[page 641] - - maxsize wide characters of s shall be accessed by wcsnlen_s. - K.3.9.3 Extended multibyte/wide character conversion utilities - K.3.9.3.1 Restartable multibyte/wide character conversion functions -1 Unlike wcrtomb, wcrtomb_s does not permit the ps parameter (the pointer to the - conversion state) to be a null pointer. - K.3.9.3.1.1 The wcrtomb_s function - Synopsis -2 #include - errno_t wcrtomb_s(size_t * restrict retval, - char * restrict s, rsize_t smax, - wchar_t wc, mbstate_t * restrict ps); - Runtime-constraints -3 Neither retval nor ps shall be a null pointer. If s is not a null pointer, then smax - shall not equal zero and shall not be greater than RSIZE_MAX. If s is not a null pointer, - then smax shall be not be less than the number of bytes to be stored in the array pointed - to by s. If s is a null pointer, then smax shall equal zero. -4 If there is a runtime-constraint violation, then wcrtomb_s does the following. If s is - not a null pointer and smax is greater than zero and not greater than RSIZE_MAX, then - wcrtomb_s sets s[0] to the null character. If retval is not a null pointer, then - wcrtomb_s sets *retval to (size_t)(-1). - Description -5 If s is a null pointer, the wcrtomb_s function is equivalent to the call - wcrtomb_s(&retval, buf, sizeof buf, L'\0', ps) - where retval and buf are internal variables of the appropriate types, and the size of - buf is greater than MB_CUR_MAX. -6 If s is not a null pointer, the wcrtomb_s function determines the number of bytes - needed to represent the multibyte character that corresponds to the wide character given - by wc (including any shift sequences), and stores the multibyte character representation - in the array whose first element is pointed to by s. At most MB_CUR_MAX bytes are - stored. If wc is a null wide character, a null byte is stored, preceded by any shift - sequence needed to restore the initial shift state; the resulting state described is the initial - conversion state. - - 432) Note that the wcsnlen_s function has no runtime-constraints. This lack of runtime-constraints - along with the values returned for a null pointer or an unterminated wide string argument make - wcsnlen_s useful in algorithms that gracefully handle such exceptional data. - -[page 642] - -7 If wc does not correspond to a valid multibyte character, an encoding error occurs: the - wcrtomb_s function stores the value (size_t)(-1) into *retval and the - conversion state is unspecified. Otherwise, the wcrtomb_s function stores into - *retval the number of bytes (including any shift sequences) stored in the array pointed - to by s. - Returns -8 The wcrtomb_s function returns zero if no runtime-constraint violation and no - encoding error occurred. Otherwise, a nonzero value is returned. - K.3.9.3.2 Restartable multibyte/wide string conversion functions -1 Unlike mbsrtowcs and wcsrtombs, mbsrtowcs_s and wcsrtombs_s do not - permit the ps parameter (the pointer to the conversion state) to be a null pointer. - K.3.9.3.2.1 The mbsrtowcs_s function - Synopsis -2 #include - errno_t mbsrtowcs_s(size_t * restrict retval, - wchar_t * restrict dst, rsize_t dstmax, - const char ** restrict src, rsize_t len, - mbstate_t * restrict ps); - Runtime-constraints -3 None of retval, src, *src, or ps shall be null pointers. If dst is not a null pointer, - then neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null - pointer, then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall - not equal zero. If dst is not a null pointer and len is not less than dstmax, then a null - character shall occur within the first dstmax multibyte characters of the array pointed to - by *src. -4 If there is a runtime-constraint violation, then mbsrtowcs_s does the following. If - retval is not a null pointer, then mbsrtowcs_s sets *retval to (size_t)(-1). - If dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX, - then mbsrtowcs_s sets dst[0] to the null wide character. - Description -5 The mbsrtowcs_s function converts a sequence of multibyte characters that begins in - the conversion state described by the object pointed to by ps, from the array indirectly - pointed to by src into a sequence of corresponding wide characters. If dst is not a null - pointer, the converted characters are stored into the array pointed to by dst. Conversion - continues up to and including a terminating null character, which is also stored. - Conversion stops earlier in two cases: when a sequence of bytes is encountered that does - not form a valid multibyte character, or (if dst is not a null pointer) when len wide -[page 643] - - characters have been stored into the array pointed to by dst.433) If dst is not a null - pointer and no null wide character was stored into the array pointed to by dst, then - dst[len] is set to the null wide character. Each conversion takes place as if by a call - to the mbrtowc function. -6 If dst is not a null pointer, the pointer object pointed to by src is assigned either a null - pointer (if conversion stopped due to reaching a terminating null character) or the address - just past the last multibyte character converted (if any). If conversion stopped due to - reaching a terminating null character and if dst is not a null pointer, the resulting state - described is the initial conversion state. -7 Regardless of whether dst is or is not a null pointer, if the input conversion encounters a - sequence of bytes that do not form a valid multibyte character, an encoding error occurs: - the mbsrtowcs_s function stores the value (size_t)(-1) into *retval and the - conversion state is unspecified. Otherwise, the mbsrtowcs_s function stores into - *retval the number of multibyte characters successfully converted, not including the - terminating null character (if any). -8 All elements following the terminating null wide character (if any) written by - mbsrtowcs_s in the array of dstmax wide characters pointed to by dst take - unspecified values when mbsrtowcs_s returns.434) -9 If copying takes place between objects that overlap, the objects take on unspecified - values. - Returns -10 The mbsrtowcs_s function returns zero if no runtime-constraint violation and no - encoding error occurred. Otherwise, a nonzero value is returned. - K.3.9.3.2.2 The wcsrtombs_s function - Synopsis -11 #include - errno_t wcsrtombs_s(size_t * restrict retval, - char * restrict dst, rsize_t dstmax, - const wchar_t ** restrict src, rsize_t len, - mbstate_t * restrict ps); - - - - - 433) Thus, the value of len is ignored if dst is a null pointer. - 434) This allows an implementation to attempt converting the multibyte string before discovering a - terminating null character did not occur where required. - -[page 644] - - Runtime-constraints -12 None of retval, src, *src, or ps shall be null pointers. If dst is not a null pointer, - then neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null - pointer, then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall - not equal zero. If dst is not a null pointer and len is not less than dstmax, then the - conversion shall have been stopped (see below) because a terminating null wide character - was reached or because an encoding error occurred. -13 If there is a runtime-constraint violation, then wcsrtombs_s does the following. If - retval is not a null pointer, then wcsrtombs_s sets *retval to (size_t)(-1). - If dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX, - then wcsrtombs_s sets dst[0] to the null character. - Description -14 The wcsrtombs_s function converts a sequence of wide characters from the array - indirectly pointed to by src into a sequence of corresponding multibyte characters that - begins in the conversion state described by the object pointed to by ps. If dst is not a - null pointer, the converted characters are then stored into the array pointed to by dst. - Conversion continues up to and including a terminating null wide character, which is also - stored. Conversion stops earlier in two cases: - -- when a wide character is reached that does not correspond to a valid multibyte - character; - -- (if dst is not a null pointer) when the next multibyte character would exceed the - limit of n total bytes to be stored into the array pointed to by dst. If the wide - character being converted is the null wide character, then n is the lesser of len or - dstmax. Otherwise, n is the lesser of len or dstmax-1. - If the conversion stops without converting a null wide character and dst is not a null - pointer, then a null character is stored into the array pointed to by dst immediately - following any multibyte characters already stored. Each conversion takes place as if by a - call to the wcrtomb function.435) -15 If dst is not a null pointer, the pointer object pointed to by src is assigned either a null - pointer (if conversion stopped due to reaching a terminating null wide character) or the - address just past the last wide character converted (if any). If conversion stopped due to - reaching a terminating null wide character, the resulting state described is the initial - conversion state. - - - 435) If conversion stops because a terminating null wide character has been reached, the bytes stored - include those necessary to reach the initial shift state immediately before the null byte. However, if - the conversion stops before a terminating null wide character has been reached, the result will be null - terminated, but might not end in the initial shift state. - -[page 645] - -16 Regardless of whether dst is or is not a null pointer, if the input conversion encounters a - wide character that does not correspond to a valid multibyte character, an encoding error - occurs: the wcsrtombs_s function stores the value (size_t)(-1) into *retval - and the conversion state is unspecified. Otherwise, the wcsrtombs_s function stores - into *retval the number of bytes in the resulting multibyte character sequence, not - including the terminating null character (if any). -17 All elements following the terminating null character (if any) written by wcsrtombs_s - in the array of dstmax elements pointed to by dst take unspecified values when - wcsrtombs_s returns.436) -18 If copying takes place between objects that overlap, the objects take on unspecified - values. - Returns -19 The wcsrtombs_s function returns zero if no runtime-constraint violation and no - encoding error occurred. Otherwise, a nonzero value is returned. - - - - - 436) When len is not less than dstmax, the implementation might fill the array before discovering a - runtime-constraint violation. - -[page 646] - - Annex L - (normative) - Analyzability - L.1 Scope -1 This annex specifies optional behavior that can aid in the analyzability of C programs. -2 An implementation that defines __STDC_ANALYZABLE__ shall conform to the - specifications in this annex.437) - L.2 Definitions - L.2.1 -1 out-of-bounds store - an (attempted) access (3.1) that, at run time, for a given computational state, would - modify (or, for an object declared volatile, fetch) one or more bytes that lie outside - the bounds permitted by this Standard. - L.2.2 -1 bounded undefined behavior - undefined behavior (3.4.3) that does not perform an out-of-bounds store. -2 NOTE 1 The behavior might perform a trap. - -3 NOTE 2 Any values produced or stored might be indeterminate values. - - L.2.3 -1 critical undefined behavior - undefined behavior that is not bounded undefined behavior. -2 NOTE The behavior might perform an out-of-bounds store or perform a trap. - - - - - 437) Implementations that do not define __STDC_ANALYZABLE__ are not required to conform to these - specifications. - -[page 647] - - L.3 Requirements -1 If the program performs a trap (3.19.5), the implementation is permitted to invoke a - runtime-constraint handler. Any such semantics are implementation-defined. -2 All undefined behavior shall be limited to bounded undefined behavior, except for the - following which are permitted to result in critical undefined behavior: - -- An object is referred to outside of its lifetime (6.2.4). - -- An lvalue does not designate an object when evaluated (6.3.2.1). - -- A pointer is used to call a function whose type is not compatible with the referenced - type (6.3.2.3). - -- The operand of the unary * operator has an invalid value (6.5.3.2). - -- Addition or subtraction of a pointer into, or just beyond, an array object and an - integer type produces a result that points just beyond the array object and is used as - the operand of a unary * operator that is evaluated (6.5.6). - -- An argument to a library function has an invalid value or a type not expected by a - function with variable number of arguments (7.1.4). - -- The value of a pointer that refers to space deallocated by a call to the free or realloc - function is used (7.22.3). - -- A string or wide string utility function is instructed to access an array beyond the end - of an object (7.23.1, 7.28.4). - - - - -[page 648] - - - Bibliography - 1. ''The C Reference Manual'' by Dennis M. Ritchie, a version of which was - published in The C Programming Language by Brian W. Kernighan and Dennis - M. Ritchie, Prentice-Hall, Inc., (1978). Copyright owned by AT&T. - 2. 1984 /usr/group Standard by the /usr/group Standards Committee, Santa Clara, - California, USA, November 1984. - 3. ANSI X3/TR-1-82 (1982), American National Dictionary for Information - Processing Systems, Information Processing Systems Technical Report. - 4. ANSI/IEEE 754-1985, American National Standard for Binary Floating-Point - Arithmetic. - 5. ANSI/IEEE 854-1988, American National Standard for Radix-Independent - Floating-Point Arithmetic. - 6. IEC 60559:1989, Binary floating-point arithmetic for microprocessor systems, - second edition (previously designated IEC 559:1989). - 7. ISO 31-11:1992, Quantities and units -- Part 11: Mathematical signs and - symbols for use in the physical sciences and technology. - 8. ISO/IEC 646:1991, Information technology -- ISO 7-bit coded character set for - information interchange. - 9. ISO/IEC 2382-1:1993, Information technology -- Vocabulary -- Part 1: - Fundamental terms. - 10. ISO 4217:1995, Codes for the representation of currencies and funds. - 11. ISO 8601:1988, Data elements and interchange formats -- Information - interchange -- Representation of dates and times. - 12. ISO/IEC 9899:1990, Programming languages -- C. - 13. ISO/IEC 9899/COR1:1994, Technical Corrigendum 1. - 14. ISO/IEC 9899/COR2:1996, Technical Corrigendum 2. - 15. ISO/IEC 9899/AMD1:1995, Amendment 1 to ISO/IEC 9899:1990 C Integrity. - 16. ISO/IEC 9899:1999, Programming languages -- C. - 17. ISO/IEC 9899:1999/Cor.1:2001, Technical Corrigendum 1. - 18. ISO/IEC 9899:1999/Cor.2:2004, Technical Corrigendum 2. - 19. ISO/IEC 9899:1999/Cor.3:2007, Technical Corrigendum 3. - - - -[page 649] - - 20. ISO/IEC 9945-2:1993, Information technology -- Portable Operating System - Interface (POSIX) -- Part 2: Shell and Utilities. - 21. ISO/IEC TR 10176:1998, Information technology -- Guidelines for the - preparation of programming language standards. - 22. ISO/IEC 10646-1:1993, Information technology -- Universal Multiple-Octet - Coded Character Set (UCS) -- Part 1: Architecture and Basic Multilingual Plane. - 23. ISO/IEC 10646-1/COR1:1996, Technical Corrigendum 1 to - ISO/IEC 10646-1:1993. - 24. ISO/IEC 10646-1/COR2:1998, Technical Corrigendum 2 to - ISO/IEC 10646-1:1993. - 25. ISO/IEC 10646-1/AMD1:1996, Amendment 1 to ISO/IEC 10646-1:1993 - Transformation Format for 16 planes of group 00 (UTF-16). - 26. ISO/IEC 10646-1/AMD2:1996, Amendment 2 to ISO/IEC 10646-1:1993 UCS - Transformation Format 8 (UTF-8). - 27. ISO/IEC 10646-1/AMD3:1996, Amendment 3 to ISO/IEC 10646-1:1993. - 28. ISO/IEC 10646-1/AMD4:1996, Amendment 4 to ISO/IEC 10646-1:1993. - 29. ISO/IEC 10646-1/AMD5:1998, Amendment 5 to ISO/IEC 10646-1:1993 Hangul - syllables. - 30. ISO/IEC 10646-1/AMD6:1997, Amendment 6 to ISO/IEC 10646-1:1993 - Tibetan. - 31. ISO/IEC 10646-1/AMD7:1997, Amendment 7 to ISO/IEC 10646-1:1993 33 - additional characters. - 32. ISO/IEC 10646-1/AMD8:1997, Amendment 8 to ISO/IEC 10646-1:1993. - 33. ISO/IEC 10646-1/AMD9:1997, Amendment 9 to ISO/IEC 10646-1:1993 - Identifiers for characters. - 34. ISO/IEC 10646-1/AMD10:1998, Amendment 10 to ISO/IEC 10646-1:1993 - Ethiopic. - 35. ISO/IEC 10646-1/AMD11:1998, Amendment 11 to ISO/IEC 10646-1:1993 - Unified Canadian Aboriginal Syllabics. - 36. ISO/IEC 10646-1/AMD12:1998, Amendment 12 to ISO/IEC 10646-1:1993 - Cherokee. - 37. ISO/IEC 10967-1:1994, Information technology -- Language independent - arithmetic -- Part 1: Integer and floating point arithmetic. - - -[page 650] - - 38. ISO/IEC TR 19769:2004, Information technology -- Programming languages, - their environments and system software interfaces -- Extensions for the - programming language C to support new character data types. - 39. ISO/IEC TR 24731-1:2007, Information technology -- Programming languages, - their environments and system software interfaces -- Extensions to the C library - -- Part 1: Bounds-checking interfaces. - - - - -[page 651] - - - -[page 652] - - -Index -[^ x ^], 3.20 , (comma operator), 5.1.2.4, 6.5.17 - , (comma punctuator), 6.5.2, 6.7, 6.7.2.1, 6.7.2.2, -[_ x _], 3.21 6.7.2.3, 6.7.9 -! (logical negation operator), 6.5.3.3 - (subtraction operator), 6.2.6.2, 6.5.6, F.3, G.5.2 -!= (inequality operator), 6.5.9 - (unary minus operator), 6.5.3.3, F.3 -# operator, 6.10.3.2 -- (postfix decrement operator), 6.3.2.1, 6.5.2.4 -# preprocessing directive, 6.10.7 -- (prefix decrement operator), 6.3.2.1, 6.5.3.1 -# punctuator, 6.10 -= (subtraction assignment operator), 6.5.16.2 -## operator, 6.10.3.3 -> (structure/union pointer operator), 6.5.2.3 -#define preprocessing directive, 6.10.3 . (structure/union member operator), 6.3.2.1, -#elif preprocessing directive, 6.10.1 6.5.2.3 -#else preprocessing directive, 6.10.1 . punctuator, 6.7.9 -#endif preprocessing directive, 6.10.1 ... (ellipsis punctuator), 6.5.2.2, 6.7.6.3, 6.10.3 -#error preprocessing directive, 4, 6.10.5 / (division operator), 6.2.6.2, 6.5.5, F.3, G.5.1 -#if preprocessing directive, 5.2.4.2.1, 5.2.4.2.2, /* */ (comment delimiters), 6.4.9 - 6.10.1, 7.1.4 // (comment delimiter), 6.4.9 -#ifdef preprocessing directive, 6.10.1 /= (division assignment operator), 6.5.16.2 -#ifndef preprocessing directive, 6.10.1 : (colon punctuator), 6.7.2.1 -#include preprocessing directive, 5.1.1.2, :> (alternative spelling of ]), 6.4.6 - 6.10.2 ; (semicolon punctuator), 6.7, 6.7.2.1, 6.8.3, -#line preprocessing directive, 6.10.4 6.8.5, 6.8.6 -#pragma preprocessing directive, 6.10.6 < (less-than operator), 6.5.8 -#undef preprocessing directive, 6.10.3.5, 7.1.3, <% (alternative spelling of {), 6.4.6 - 7.1.4 <: (alternative spelling of [), 6.4.6 -% (remainder operator), 6.2.6.2, 6.5.5 << (left-shift operator), 6.2.6.2, 6.5.7 -%: (alternative spelling of #), 6.4.6 <<= (left-shift assignment operator), 6.5.16.2 -%:%: (alternative spelling of ##), 6.4.6 <= (less-than-or-equal-to operator), 6.5.8 -%= (remainder assignment operator), 6.5.16.2 header, 7.2 -%> (alternative spelling of }), 6.4.6 header, 5.2.4.2.2, 6.10.8.3, 7.1.2, -& (address operator), 6.3.2.1, 6.5.3.2 7.3, 7.24, 7.30.1, G.6, J.5.17 -& (bitwise AND operator), 6.2.6.2, 6.5.10 header, 7.4, 7.30.2 -&& (logical AND operator), 5.1.2.4, 6.5.13 header, 7.5, 7.30.3, K.3.2 -&= (bitwise AND assignment operator), 6.5.16.2 header, 5.1.2.3, 5.2.4.2.2, 7.6, 7.12, F, -' ' (space character), 5.1.1.2, 5.2.1, 6.4, 7.4.1.3, H - 7.4.1.10, 7.29.2.1.3 header, 4, 5.2.4.2.2, 7.7, 7.22.1.3, -( ) (cast operator), 6.5.4 7.28.4.1.1 -( ) (function-call operator), 6.5.2.2 header, 7.8, 7.30.4 -( ) (parentheses punctuator), 6.7.6.3, 6.8.4, 6.8.5 header, 4, 7.9 -( ){ } (compound-literal operator), 6.5.2.5 header, 4, 5.2.4.2.1, 6.2.5, 7.10 -* (asterisk punctuator), 6.7.6.1, 6.7.6.2 header, 7.11, 7.30.5 -* (indirection operator), 6.5.2.1, 6.5.3.2 header, 5.2.4.2.2, 6.5, 7.12, 7.24, F, -* (multiplication operator), 6.2.6.2, 6.5.5, F.3, F.10, J.5.17 - G.5.1 header, 7.13 -*= (multiplication assignment operator), 6.5.16.2 header, 7.14, 7.30.6 -+ (addition operator), 6.2.6.2, 6.5.2.1, 6.5.3.2, header, 4, 7.15 - 6.5.6, F.3, G.5.2 header, 4, 6.7.6.3, 7.16 -+ (unary plus operator), 6.5.3.3 header, 6.10.8.3, 7.1.2, 7.17 -++ (postfix increment operator), 6.3.2.1, 6.5.2.4 header, 4, 7.18, 7.30.7, H -++ (prefix increment operator), 6.3.2.1, 6.5.3.1 header, 4, 6.3.2.1, 6.3.2.3, 6.4.4.4, -+= (addition assignment operator), 6.5.16.2 -[page 653] - - 6.4.5, 6.5.3.4, 6.5.6, 7.19, K.3.3 \x hexadecimal digits (hexadecimal-character - header, 4, 5.2.4.2, 6.10.1, 7.8, escape sequence), 6.4.4.4 - 7.20, 7.30.8, K.3.3, K.3.4 ^ (bitwise exclusive OR operator), 6.2.6.2, 6.5.11 - header, 5.2.4.2.2, 7.21, 7.30.9, F, ^= (bitwise exclusive OR assignment operator), - K.3.5 6.5.16.2 - header, 5.2.4.2.2, 7.22, 7.30.10, F, __alignas_is_defined macro, 7.15 - K.3.1.4, K.3.6 __bool_true_false_are_defined - header, 7.23, 7.30.11, K.3.7 macro, 7.18 - header, 7.24, G.7 __cplusplus macro, 6.10.8 - header, 6.10.8.3, 7.1.2, 7.25 __DATE__ macro, 6.10.8.1 - header, 7.26, K.3.8 __FILE__ macro, 6.10.8.1, 7.2.1.1 - header, 6.4.4.4, 6.4.5, 7.27 __func__ identifier, 6.4.2.2, 7.2.1.1 - header, 5.2.4.2.2, 7.21.1, 7.28, __LINE__ macro, 6.10.8.1, 7.2.1.1 - 7.30.12, F, K.3.9 __STDC_, 6.11.9 - header, 7.29, 7.30.13 __STDC__ macro, 6.10.8.1 -= (equal-sign punctuator), 6.7, 6.7.2.2, 6.7.9 __STDC_ANALYZABLE__ macro, 6.10.8.3, L.1 -= (simple assignment operator), 6.5.16.1 __STDC_HOSTED__ macro, 6.10.8.1 -== (equality operator), 6.5.9 __STDC_IEC_559__ macro, 6.10.8.3, F.1 -> (greater-than operator), 6.5.8 __STDC_IEC_559_COMPLEX__ macro, ->= (greater-than-or-equal-to operator), 6.5.8 6.10.8.3, G.1 ->> (right-shift operator), 6.2.6.2, 6.5.7 __STDC_ISO_10646__ macro, 6.10.8.2 ->>= (right-shift assignment operator), 6.5.16.2 __STDC_LIB_EXT1__ macro, 6.10.8.3, K.2 -? : (conditional operator), 5.1.2.4, 6.5.15 __STDC_MB_MIGHT_NEQ_WC__ macro, -?? (trigraph sequences), 5.2.1.1 6.10.8.2, 7.19 -[ ] (array subscript operator), 6.5.2.1, 6.5.3.2 __STDC_NO_COMPLEX__ macro, 6.10.8.3, -[ ] (brackets punctuator), 6.7.6.2, 6.7.9 7.3.1 -\ (backslash character), 5.1.1.2, 5.2.1, 6.4.4.4 __STDC_NO_THREADS__ macro, 6.10.8.3, -\ (escape character), 6.4.4.4 7.17.1, 7.25.1 -\" (double-quote escape sequence), 6.4.4.4, __STDC_NO_VLA__ macro, 6.10.8.3 - 6.4.5, 6.10.9 __STDC_UTF_16__ macro, 6.10.8.2 -\\ (backslash escape sequence), 6.4.4.4, 6.10.9 __STDC_UTF_32__ macro, 6.10.8.2 -\' (single-quote escape sequence), 6.4.4.4, 6.4.5 __STDC_VERSION__ macro, 6.10.8.1 -\0 (null character), 5.2.1, 6.4.4.4, 6.4.5 __STDC_WANT_LIB_EXT1__ macro, K.3.1.1 - padding of binary stream, 7.21.2 __TIME__ macro, 6.10.8.1 -\? (question-mark escape sequence), 6.4.4.4 __VA_ARGS__ identifier, 6.10.3, 6.10.3.1 -\a (alert escape sequence), 5.2.2, 6.4.4.4 _Alignas, 6.7.5 -\b (backspace escape sequence), 5.2.2, 6.4.4.4 _Atomic type qualifier, 6.7.2, 6.7.3 -\f (form-feed escape sequence), 5.2.2, 6.4.4.4, _Atomic-qualified type, 6.2.5, 6.2.6.1, 6.5.2.3, - 7.4.1.10 6.5.2.4, 6.5.16.2, 6.7.2, 6.7.3 -\n (new-line escape sequence), 5.2.2, 6.4.4.4, _Bool type, 6.2.5, 6.3.1.1, 6.3.1.2, 6.7.2, 7.17.1, - 7.4.1.10 F.4 -\octal digits (octal-character escape sequence), _Bool type conversions, 6.3.1.2 - 6.4.4.4 _Complex types, 6.2.5, 6.7.2, 7.3.1, G -\r (carriage-return escape sequence), 5.2.2, _Complex_I macro, 7.3.1 - 6.4.4.4, 7.4.1.10 _Exit function, 7.22.4.5, 7.22.4.7 -\t (horizontal-tab escape sequence), 5.2.2, _Imaginary keyword, G.2 - 6.4.4.4, 7.4.1.3, 7.4.1.10, 7.29.2.1.3 _Imaginary types, 7.3.1, G -\U (universal character names), 6.4.3 _Imaginary_I macro, 7.3.1, G.6 -\u (universal character names), 6.4.3 _IOFBF macro, 7.21.1, 7.21.5.5, 7.21.5.6 -\v (vertical-tab escape sequence), 5.2.2, 6.4.4.4, _IOLBF macro, 7.21.1, 7.21.5.6 - 7.4.1.10 _IONBF macro, 7.21.1, 7.21.5.5, 7.21.5.6 - -[page 654] - -_Noreturn, 6.7.4 alignment specifier, 6.7.5 -_Pragma operator, 5.1.1.2, 6.10.9 alignof operator, 6.5.3, 6.5.3.4 -_Static_assert, 6.7.10, 7.2 allocated storage, order and contiguity, 7.22.3 -_Thread_local storage-class specifier, 6.2.4, and macro, 7.9 - 6.7.1 AND operators -{ } (braces punctuator), 6.7.2.2, 6.7.2.3, 6.7.9, bitwise (&), 6.2.6.2, 6.5.10 - 6.8.2 bitwise assignment (&=), 6.5.16.2 -{ } (compound-literal operator), 6.5.2.5 logical (&&), 5.1.2.4, 6.5.13 -| (bitwise inclusive OR operator), 6.2.6.2, 6.5.12 and_eq macro, 7.9 -|= (bitwise inclusive OR assignment operator), anonymous structure, 6.7.2.1 - 6.5.16.2 anonymous union, 6.7.2.1 -|| (logical OR operator), 5.1.2.4, 6.5.14 ANSI/IEEE 754, F.1 -~ (bitwise complement operator), 6.2.6.2, 6.5.3.3 ANSI/IEEE 854, F.1 - argc (main function parameter), 5.1.2.2.1 -abort function, 7.2.1.1, 7.14.1.1, 7.21.3, argument, 3.3 - 7.22.4.1, 7.25.3.6, K.3.6.1.2 array, 6.9.1 -abort_handler_s function, K.3.6.1.2 default promotions, 6.5.2.2 -abs function, 7.22.6.1 function, 6.5.2.2, 6.9.1 -absolute-value functions macro, substitution, 6.10.3.1 - complex, 7.3.8, G.6.4 argument, complex, 7.3.9.1 - integer, 7.8.2.1, 7.22.6.1 argv (main function parameter), 5.1.2.2.1 - real, 7.12.7, F.10.4 arithmetic constant expression, 6.6 -abstract declarator, 6.7.7 arithmetic conversions, usual, see usual arithmetic -abstract machine, 5.1.2.3 conversions -access, 3.1, 6.7.3, L.2.1 arithmetic operators -accuracy, see floating-point accuracy additive, 6.2.6.2, 6.5.6, G.5.2 -acos functions, 7.12.4.1, F.10.1.1 bitwise, 6.2.6.2, 6.5.3.3, 6.5.10, 6.5.11, 6.5.12 -acos type-generic macro, 7.24 increment and decrement, 6.5.2.4, 6.5.3.1 -acosh functions, 7.12.5.1, F.10.2.1 multiplicative, 6.2.6.2, 6.5.5, G.5.1 -acosh type-generic macro, 7.24 shift, 6.2.6.2, 6.5.7 -acquire fence, 7.17.4 unary, 6.5.3.3 -acquire operation, 5.1.2.4 arithmetic types, 6.2.5 -active position, 5.2.2 arithmetic, pointer, 6.5.6 -actual argument, 3.3 array -actual parameter (deprecated), 3.3 argument, 6.9.1 -addition assignment operator (+=), 6.5.16.2 declarator, 6.7.6.2 -addition operator (+), 6.2.6.2, 6.5.2.1, 6.5.3.2, initialization, 6.7.9 - 6.5.6, F.3, G.5.2 multidimensional, 6.5.2.1 -additive expressions, 6.5.6, G.5.2 parameter, 6.9.1 -address constant, 6.6 storage order, 6.5.2.1 -address operator (&), 6.3.2.1, 6.5.3.2 subscript operator ([ ]), 6.5.2.1, 6.5.3.2 -address-free, 7.17.5 subscripting, 6.5.2.1 -aggregate initialization, 6.7.9 type, 6.2.5 -aggregate types, 6.2.5 type conversion, 6.3.2.1 -alert escape sequence (\a), 5.2.2, 6.4.4.4 variable length, 6.7.6, 6.7.6.2, 6.10.8.3 -aliasing, 6.5 arrow operator (->), 6.5.2.3 -alignas macro, 7.15 as-if rule, 5.1.2.3 -aligned_alloc function, 7.22.3, 7.22.3.1 ASCII code set, 5.2.1.1 -alignment, 3.2, 6.2.8, 7.22.3.1 asctime function, 7.26.3.1 - pointer, 6.2.5, 6.3.2.3 asctime_s function, K.3.8.2, K.3.8.2.1 - structure/union member, 6.7.2.1 asin functions, 7.12.4.2, F.10.1.2 - -[page 655] - -asin type-generic macro, 7.24, G.7 atomic_is_lock_free generic function, -asinh functions, 7.12.5.2, F.10.2.2 7.17.5.1 -asinh type-generic macro, 7.24, G.7 ATOMIC_LLONG_LOCK_FREE macro, 7.17.1 -asm keyword, J.5.10 atomic_load generic functions, 7.17.7.2 -assert macro, 7.2.1.1 ATOMIC_LONG_LOCK_FREE macro, 7.17.1 -assert.h header, 7.2 ATOMIC_SHORT_LOCK_FREE macro, 7.17.1 -assignment atomic_signal_fence function, 7.17.4.2 - compound, 6.5.16.2 atomic_store generic functions, 7.17.7.1 - conversion, 6.5.16.1 atomic_thread_fence function, 7.17.4.1 - expression, 6.5.16 ATOMIC_VAR_INIT macro, 7.17.2.1 - operators, 6.3.2.1, 6.5.16 ATOMIC_WCHAR_T_LOCK_FREE macro, 7.17.1 - simple, 6.5.16.1 atomics header, 7.17 -associativity of operators, 6.5 auto storage-class specifier, 6.7.1, 6.9 -asterisk punctuator (*), 6.7.6.1, 6.7.6.2 automatic storage duration, 5.2.3, 6.2.4 -at_quick_exit function, 7.22.4.2, 7.22.4.3, - 7.22.4.4, 7.22.4.5, 7.22.4.7 backslash character (\), 5.1.1.2, 5.2.1, 6.4.4.4 -atan functions, 7.12.4.3, F.10.1.3 backslash escape sequence (\\), 6.4.4.4, 6.10.9 -atan type-generic macro, 7.24, G.7 backspace escape sequence (\b), 5.2.2, 6.4.4.4 -atan2 functions, 7.12.4.4, F.10.1.4 basic character set, 3.6, 3.7.2, 5.2.1 -atan2 type-generic macro, 7.24 basic types, 6.2.5 -atanh functions, 7.12.5.3, F.10.2.3 behavior, 3.4 -atanh type-generic macro, 7.24, G.7 binary streams, 7.21.2, 7.21.7.10, 7.21.9.2, -atexit function, 7.22.4.2, 7.22.4.3, 7.22.4.4, 7.21.9.4 - 7.22.4.5, 7.22.4.7, J.5.13 bit, 3.5 -atof function, 7.22.1, 7.22.1.1 high order, 3.6 -atoi function, 7.22.1, 7.22.1.2 low order, 3.6 -atol function, 7.22.1, 7.22.1.2 bit-field, 6.7.2.1 -atoll function, 7.22.1, 7.22.1.2 bitand macro, 7.9 -atomic lock-free macros, 7.17.1, 7.17.5 bitor macro, 7.9 -atomic operations, 5.1.2.4 bitwise operators, 6.5 -atomic types, 5.1.2.3, 6.10.8.3, 7.17.6 AND, 6.2.6.2, 6.5.10 -atomic_address type, 7.17.1, 7.17.6 AND assignment (&=), 6.5.16.2 -ATOMIC_ADDRESS_LOCK_FREE macro, 7.17.1 complement (~), 6.2.6.2, 6.5.3.3 -atomic_bool type, 7.17.1, 7.17.6 exclusive OR, 6.2.6.2, 6.5.11 -ATOMIC_CHAR16_T_LOCK_FREE macro, exclusive OR assignment (^=), 6.5.16.2 - 7.17.1 inclusive OR, 6.2.6.2, 6.5.12 -ATOMIC_CHAR32_T_LOCK_FREE macro, inclusive OR assignment (|=), 6.5.16.2 - 7.17.1 shift, 6.2.6.2, 6.5.7 -ATOMIC_CHAR_LOCK_FREE macro, 7.17.1 blank character, 7.4.1.3 -atomic_compare_exchange generic block, 6.8, 6.8.2, 6.8.4, 6.8.5 - functions, 7.17.7.4 block scope, 6.2.1 -atomic_exchange generic functions, 7.17.7.3 block structure, 6.2.1 -atomic_fetch and modify generic functions, bold type convention, 6.1 - 7.17.7.5 bool macro, 7.18 -atomic_flag type, 7.17.1, 7.17.8 boolean type, 6.3.1.2 -atomic_flag_clear functions, 7.17.8.2 boolean type conversion, 6.3.1.1, 6.3.1.2 -ATOMIC_FLAG_INIT macro, 7.17.1, 7.17.8 bounded undefined behavior, L.2.2 -atomic_flag_test_and_set functions, braces punctuator ({ }), 6.7.2.2, 6.7.2.3, 6.7.9, - 7.17.8.1 6.8.2 -atomic_init generic function, 7.17.2.2 brackets operator ([ ]), 6.5.2.1, 6.5.3.2 -ATOMIC_INT_LOCK_FREE macro, 7.17.1 brackets punctuator ([ ]), 6.7.6.2, 6.7.9 - -[page 656] - -branch cuts, 7.3.3 type-generic macro for, 7.24 -break statement, 6.8.6.3 ccosh functions, 7.3.6.4, G.6.2.4 -broken-down time, 7.26.1, 7.26.2.3, 7.26.3, type-generic macro for, 7.24 - 7.26.3.1, 7.26.3.3, 7.26.3.4, 7.26.3.5, ceil functions, 7.12.9.1, F.10.6.1 - K.3.8.2.1, K.3.8.2.3, K.3.8.2.4 ceil type-generic macro, 7.24 -bsearch function, 7.22.5, 7.22.5.1 cerf function, 7.30.1 -bsearch_s function, K.3.6.3, K.3.6.3.1 cerfc function, 7.30.1 -btowc function, 7.28.6.1.1 cexp functions, 7.3.7.1, G.6.3.1 -BUFSIZ macro, 7.21.1, 7.21.2, 7.21.5.5 type-generic macro for, 7.24 -byte, 3.6, 6.5.3.4 cexp2 function, 7.30.1 -byte input/output functions, 7.21.1 cexpm1 function, 7.30.1 -byte-oriented stream, 7.21.2 char type, 6.2.5, 6.3.1.1, 6.7.2, K.3.5.3.2, - K.3.9.1.2 -C program, 5.1.1.1 char type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4, -c16rtomb function, 7.27.1.2 6.3.1.8 -c32rtomb function, 7.27.1.4 char16_t type, 6.4.4.4, 6.4.5, 6.10.8.2, 7.27 -cabs functions, 7.3.8.1, G.6 char32_t type, 6.4.4.4, 6.4.5, 6.10.8.2, 7.27 - type-generic macro for, 7.24 CHAR_BIT macro, 5.2.4.2.1, 6.7.2.1 -cacos functions, 7.3.5.1, G.6.1.1 CHAR_MAX macro, 5.2.4.2.1, 7.11.2.1 - type-generic macro for, 7.24 CHAR_MIN macro, 5.2.4.2.1 -cacosh functions, 7.3.6.1, G.6.2.1 character, 3.7, 3.7.1 - type-generic macro for, 7.24 character array initialization, 6.7.9 -calendar time, 7.26.1, 7.26.2.2, 7.26.2.3, 7.26.2.4, character case mapping functions, 7.4.2 - 7.26.3.2, 7.26.3.3, 7.26.3.4, K.3.8.2.2, wide character, 7.29.3.1 - K.3.8.2.3, K.3.8.2.4 extensible, 7.29.3.2 -call by value, 6.5.2.2 character classification functions, 7.4.1 -call_once function, 7.25.1, 7.25.2.1 wide character, 7.29.2.1 -calloc function, 7.22.3, 7.22.3.2 extensible, 7.29.2.2 -carg functions, 7.3.9.1, G.6 character constant, 5.1.1.2, 5.2.1, 6.4.4.4 -carg type-generic macro, 7.24, G.7 character display semantics, 5.2.2 -carriage-return escape sequence (\r), 5.2.2, character handling header, 7.4, 7.11.1.1 - 6.4.4.4, 7.4.1.10 character input/output functions, 7.21.7, K.3.5.4 -carries a dependency, 5.1.2.4 wide character, 7.28.3 -case label, 6.8.1, 6.8.4.2 character sets, 5.2.1 -case mapping functions character string literal, see string literal - character, 7.4.2 character type conversion, 6.3.1.1 - wide character, 7.29.3.1 character types, 6.2.5, 6.7.9 - extensible, 7.29.3.2 cimag functions, 7.3.9.2, 7.3.9.5, G.6 -casin functions, 7.3.5.2, G.6 cimag type-generic macro, 7.24, G.7 - type-generic macro for, 7.24 cis function, G.6 -casinh functions, 7.3.6.2, G.6.2.2 classification functions - type-generic macro for, 7.24 character, 7.4.1 -cast expression, 6.5.4 floating-point, 7.12.3 -cast operator (( )), 6.5.4 wide character, 7.29.2.1 -catan functions, 7.3.5.3, G.6 extensible, 7.29.2.2 - type-generic macro for, 7.24 clearerr function, 7.21.10.1 -catanh functions, 7.3.6.3, G.6.2.3 clgamma function, 7.30.1 - type-generic macro for, 7.24 clock function, 7.26.2.1 -cbrt functions, 7.12.7.1, F.10.4.1 clock_t type, 7.26.1, 7.26.2.1 -cbrt type-generic macro, 7.24 CLOCKS_PER_SEC macro, 7.26.1, 7.26.2.1 -ccos functions, 7.3.5.4, G.6 clog functions, 7.3.7.2, G.6.3.2 - -[page 657] - - type-generic macro for, 7.24 string, 7.23.3, K.3.7.2 -clog10 function, 7.30.1 wide string, 7.28.4.3, K.3.9.2.2 -clog1p function, 7.30.1 concatenation, preprocessing, see preprocessing -clog2 function, 7.30.1 concatenation -CMPLX macros, 7.3.9.3 conceptual models, 5.1 -cnd_broadcast function, 7.25.3.1, 7.25.3.5, conditional features, 4, 6.2.5, 6.7.6.2, 6.10.8.3, - 7.25.3.6 7.1.2, F.1, G.1, K.2, L.1 -cnd_destroy function, 7.25.3.2 conditional inclusion, 6.10.1 -cnd_init function, 7.25.3.3 conditional operator (? :), 5.1.2.4, 6.5.15 -cnd_signal function, 7.25.3.4, 7.25.3.5, conflict, 5.1.2.4 - 7.25.3.6 conformance, 4 -cnd_t type, 7.25.1 conj functions, 7.3.9.4, G.6 -cnd_timedwait function, 7.25.3.5 conj type-generic macro, 7.24 -cnd_wait function, 7.25.3.3, 7.25.3.6 const type qualifier, 6.7.3 -collating sequences, 5.2.1 const-qualified type, 6.2.5, 6.3.2.1, 6.7.3 -colon punctuator (:), 6.7.2.1 constant expression, 6.6, F.8.4 -comma operator (,), 5.1.2.4, 6.5.17 constants, 6.4.4 -comma punctuator (,), 6.5.2, 6.7, 6.7.2.1, 6.7.2.2, as primary expression, 6.5.1 - 6.7.2.3, 6.7.9 character, 6.4.4.4 -command processor, 7.22.4.8 enumeration, 6.2.1, 6.4.4.3 -comment delimiters (/* */ and //), 6.4.9 floating, 6.4.4.2 -comments, 5.1.1.2, 6.4, 6.4.9 hexadecimal, 6.4.4.1 -common extensions, J.5 integer, 6.4.4.1 -common initial sequence, 6.5.2.3 octal, 6.4.4.1 -common real type, 6.3.1.8 constraint, 3.8, 4 -common warnings, I constraint_handler_t type, K.3.6 -comparison functions, 7.22.5, 7.22.5.1, 7.22.5.2, consume operation, 5.1.2.4 - K.3.6.3, K.3.6.3.1, K.3.6.3.2 content of structure/union/enumeration, 6.7.2.3 - string, 7.23.4 contiguity of allocated storage, 7.22.3 - wide string, 7.28.4.4 continue statement, 6.8.6.2 -comparison macros, 7.12.14 contracted expression, 6.5, 7.12.2, F.7 -comparison, pointer, 6.5.8 control character, 5.2.1, 7.4 -compatible type, 6.2.7, 6.7.2, 6.7.3, 6.7.6 control wide character, 7.29.2 -compl macro, 7.9 conversion, 6.3 -complement operator (~), 6.2.6.2, 6.5.3.3 arithmetic operands, 6.3.1 -complete type, 6.2.5 array argument, 6.9.1 -complex macro, 7.3.1 array parameter, 6.9.1 -complex numbers, 6.2.5, G arrays, 6.3.2.1 -complex type conversion, 6.3.1.6, 6.3.1.7 boolean, 6.3.1.2 -complex type domain, 6.2.5 boolean, characters, and integers, 6.3.1.1 -complex types, 6.2.5, 6.7.2, 6.10.8.3, G by assignment, 6.5.16.1 -complex.h header, 5.2.4.2.2, 6.10.8.3, 7.1.2, by return statement, 6.8.6.4 - 7.3, 7.24, 7.30.1, G.6, J.5.17 complex types, 6.3.1.6 -compliance, see conformance explicit, 6.3 -components of time, 7.26.1, K.3.8.1 function, 6.3.2.1 -composite type, 6.2.7 function argument, 6.5.2.2, 6.9.1 -compound assignment, 6.5.16.2 function designators, 6.3.2.1 -compound literals, 6.5.2.5 function parameter, 6.9.1 -compound statement, 6.8.2 imaginary, G.4.1 -compound-literal operator (( ){ }), 6.5.2.5 imaginary and complex, G.4.3 -concatenation functions implicit, 6.3 - -[page 658] - - lvalues, 6.3.2.1 csinh functions, 7.3.6.5, G.6.2.5 - pointer, 6.3.2.1, 6.3.2.3 type-generic macro for, 7.24 - real and complex, 6.3.1.7 csqrt functions, 7.3.8.3, G.6.4.2 - real and imaginary, G.4.2 type-generic macro for, 7.24 - real floating and integer, 6.3.1.4, F.3, F.4 ctan functions, 7.3.5.6, G.6 - real floating types, 6.3.1.5, F.3 type-generic macro for, 7.24 - signed and unsigned integers, 6.3.1.3 ctanh functions, 7.3.6.6, G.6.2.6 - usual arithmetic, see usual arithmetic type-generic macro for, 7.24 - conversions ctgamma function, 7.30.1 - void type, 6.3.2.2 ctime function, 7.26.3.2 -conversion functions ctime_s function, K.3.8.2, K.3.8.2.2 - multibyte/wide character, 7.22.7, K.3.6.4 ctype.h header, 7.4, 7.30.2 - extended, 7.28.6, K.3.9.3 current object, 6.7.9 - restartable, 7.27.1, 7.28.6.3, K.3.9.3.1 CX_LIMITED_RANGE pragma, 6.10.6, 7.3.4 - multibyte/wide string, 7.22.8, K.3.6.5 - restartable, 7.28.6.4, K.3.9.3.2 data race, 5.1.2.4, 7.1.4, 7.22.2.1, 7.22.4.6, - numeric, 7.8.2.3, 7.22.1 7.23.5.8, 7.23.6.2, 7.26.3, 7.27.1, 7.28.6.3, - wide string, 7.8.2.4, 7.28.4.1 7.28.6.4 - single byte/wide character, 7.28.6.1 data stream, see streams - time, 7.26.3, K.3.8.2 date and time header, 7.26, K.3.8 - wide character, 7.28.5 Daylight Saving Time, 7.26.1 -conversion specifier, 7.21.6.1, 7.21.6.2, 7.28.2.1, DBL_DECIMAL_DIG macro, 5.2.4.2.2 - 7.28.2.2 DBL_DIG macro, 5.2.4.2.2 -conversion state, 7.22.7, 7.27.1, 7.27.1.1, DBL_EPSILON macro, 5.2.4.2.2 - 7.27.1.2, 7.27.1.3, 7.27.1.4, 7.28.6, DBL_HAS_SUBNORM macro, 5.2.4.2.2 - 7.28.6.2.1, 7.28.6.3, 7.28.6.3.2, 7.28.6.3.3, DBL_MANT_DIG macro, 5.2.4.2.2 - 7.28.6.4, 7.28.6.4.1, 7.28.6.4.2, K.3.6.4, DBL_MAX macro, 5.2.4.2.2 - K.3.9.3.1, K.3.9.3.1.1, K.3.9.3.2, K.3.9.3.2.1, DBL_MAX_10_EXP macro, 5.2.4.2.2 - K.3.9.3.2.2 DBL_MAX_EXP macro, 5.2.4.2.2 -conversion state functions, 7.28.6.2 DBL_MIN macro, 5.2.4.2.2 -copying functions DBL_MIN_10_EXP macro, 5.2.4.2.2 - string, 7.23.2, K.3.7.1 DBL_MIN_EXP macro, 5.2.4.2.2 - wide string, 7.28.4.2, K.3.9.2.1 DBL_TRUE_MIN macro, 5.2.4.2.2 -copysign functions, 7.3.9.5, 7.12.11.1, F.3, decimal constant, 6.4.4.1 - F.10.8.1 decimal digit, 5.2.1 -copysign type-generic macro, 7.24 decimal-point character, 7.1.1, 7.11.2.1 -correctly rounded result, 3.9 DECIMAL_DIG macro, 5.2.4.2.2, 7.21.6.1, -corresponding real type, 6.2.5 7.22.1.3, 7.28.2.1, 7.28.4.1.1, F.5 -cos functions, 7.12.4.5, F.10.1.5 declaration specifiers, 6.7 -cos type-generic macro, 7.24, G.7 declarations, 6.7 -cosh functions, 7.12.5.4, F.10.2.4 function, 6.7.6.3 -cosh type-generic macro, 7.24, G.7 pointer, 6.7.6.1 -cpow functions, 7.3.8.2, G.6.4.1 structure/union, 6.7.2.1 - type-generic macro for, 7.24 typedef, 6.7.8 -cproj functions, 7.3.9.5, G.6 declarator, 6.7.6 -cproj type-generic macro, 7.24 abstract, 6.7.7 -creal functions, 7.3.9.6, G.6 declarator type derivation, 6.2.5, 6.7.6 -creal type-generic macro, 7.24, G.7 decrement operators, see arithmetic operators, -critical undefined behavior, L.2.3 increment and decrement -csin functions, 7.3.5.5, G.6 default argument promotions, 6.5.2.2 - type-generic macro for, 7.24 default initialization, 6.7.9 - -[page 659] - -default label, 6.8.1, 6.8.4.2 elif preprocessing directive, 6.10.1 -define preprocessing directive, 6.10.3 ellipsis punctuator (...), 6.5.2.2, 6.7.6.3, 6.10.3 -defined operator, 6.10.1, 6.10.8 else preprocessing directive, 6.10.1 -definition, 6.7 else statement, 6.8.4.1 - function, 6.9.1 empty statement, 6.8.3 -dependency-ordered before, 5.1.2.4 encoding error, 7.21.3, 7.27.1.1, 7.27.1.2, -derived declarator types, 6.2.5 7.27.1.3, 7.27.1.4, 7.28.3.1, 7.28.3.3, -derived types, 6.2.5 7.28.6.3.2, 7.28.6.3.3, 7.28.6.4.1, 7.28.6.4.2, -designated initializer, 6.7.9 K.3.6.5.1, K.3.6.5.2, K.3.9.3.1.1, K.3.9.3.2.1, -destringizing, 6.10.9 K.3.9.3.2.2 -device input/output, 5.1.2.3 end-of-file, 7.28.1 -diagnostic message, 3.10, 5.1.1.3 end-of-file indicator, 7.21.1, 7.21.5.3, 7.21.7.1, -diagnostics, 5.1.1.3 7.21.7.5, 7.21.7.6, 7.21.7.10, 7.21.9.2, -diagnostics header, 7.2 7.21.9.3, 7.21.10.1, 7.21.10.2, 7.28.3.1, -difftime function, 7.26.2.2 7.28.3.10 -digit, 5.2.1, 7.4 end-of-file macro, see EOF macro -digraphs, 6.4.6 end-of-line indicator, 5.2.1 -direct input/output functions, 7.21.8 endif preprocessing directive, 6.10.1 -display device, 5.2.2 enum type, 6.2.5, 6.7.2, 6.7.2.2 -div function, 7.22.6.2 enumerated type, 6.2.5 -div_t type, 7.22 enumeration, 6.2.5, 6.7.2.2 -division assignment operator (/=), 6.5.16.2 enumeration constant, 6.2.1, 6.4.4.3 -division operator (/), 6.2.6.2, 6.5.5, F.3, G.5.1 enumeration content, 6.7.2.3 -do statement, 6.8.5.2 enumeration members, 6.7.2.2 -documentation of implementation, 4 enumeration specifiers, 6.7.2.2 -domain error, 7.12.1, 7.12.4.1, 7.12.4.2, 7.12.4.4, enumeration tag, 6.2.3, 6.7.2.3 - 7.12.5.1, 7.12.5.3, 7.12.6.5, 7.12.6.7, enumerator, 6.7.2.2 - 7.12.6.8, 7.12.6.9, 7.12.6.10, 7.12.6.11, environment, 5 - 7.12.7.4, 7.12.7.5, 7.12.8.4, 7.12.9.5, environment functions, 7.22.4, K.3.6.2 - 7.12.9.7, 7.12.10.1, 7.12.10.2, 7.12.10.3 environment list, 7.22.4.6, K.3.6.2.1 -dot operator (.), 6.5.2.3 environmental considerations, 5.2 -double _Complex type, 6.2.5 environmental limits, 5.2.4, 7.13.1.1, 7.21.2, -double _Complex type conversion, 6.3.1.6, 7.21.3, 7.21.4.4, 7.21.6.1, 7.22.2.1, 7.22.4.2, - 6.3.1.7, 6.3.1.8 7.22.4.3, 7.28.2.1, K.3.5.1.2 -double _Imaginary type, G.2 EOF macro, 7.4, 7.21.1, 7.21.5.1, 7.21.5.2, -double type, 6.2.5, 6.4.4.2, 6.7.2, 7.21.6.2, 7.21.6.2, 7.21.6.7, 7.21.6.9, 7.21.6.11, - 7.28.2.2, F.2 7.21.6.14, 7.21.7.1, 7.21.7.3, 7.21.7.4, -double type conversion, 6.3.1.4, 6.3.1.5, 6.3.1.7, 7.21.7.5, 7.21.7.6, 7.21.7.8, 7.21.7.9, - 6.3.1.8 7.21.7.10, 7.28.1, 7.28.2.2, 7.28.2.4, -double-precision arithmetic, 5.1.2.3 7.28.2.6, 7.28.2.8, 7.28.2.10, 7.28.2.12, -double-quote escape sequence (\"), 6.4.4.4, 7.28.3.4, 7.28.6.1.1, 7.28.6.1.2, K.3.5.3.7, - 6.4.5, 6.10.9 K.3.5.3.9, K.3.5.3.11, K.3.5.3.14, K.3.9.1.2, -double_t type, 7.12, J.5.6 K.3.9.1.5, K.3.9.1.7, K.3.9.1.10, K.3.9.1.12, - K.3.9.1.14 -EDOM macro, 7.5, 7.12.1, see also domain error equal-sign punctuator (=), 6.7, 6.7.2.2, 6.7.9 -effective type, 6.5 equal-to operator, see equality operator -EILSEQ macro, 7.5, 7.21.3, 7.27.1.1, 7.27.1.2, equality expressions, 6.5.9 - 7.27.1.3, 7.27.1.4, 7.28.3.1, 7.28.3.3, equality operator (==), 6.5.9 - 7.28.6.3.2, 7.28.6.3.3, 7.28.6.4.1, 7.28.6.4.2, ERANGE macro, 7.5, 7.8.2.3, 7.8.2.4, 7.12.1, - see also encoding error 7.22.1.3, 7.22.1.4, 7.28.4.1.1, 7.28.4.1.2, see -element type, 6.2.5 also range error, pole error - -[page 660] - -erf functions, 7.12.8.1, F.10.5.1 exp type-generic macro, 7.24 -erf type-generic macro, 7.24 exp2 functions, 7.12.6.2, F.10.3.2 -erfc functions, 7.12.8.2, F.10.5.2 exp2 type-generic macro, 7.24 -erfc type-generic macro, 7.24 explicit conversion, 6.3 -errno macro, 7.1.3, 7.3.2, 7.5, 7.8.2.3, 7.8.2.4, expm1 functions, 7.12.6.3, F.10.3.3 - 7.12.1, 7.14.1.1, 7.21.3, 7.21.9.3, 7.21.10.4, expm1 type-generic macro, 7.24 - 7.22.1, 7.22.1.3, 7.22.1.4, 7.23.6.2, 7.27.1.1, exponent part, 6.4.4.2 - 7.27.1.2, 7.27.1.3, 7.27.1.4, 7.28.3.1, exponential functions - 7.28.3.3, 7.28.4.1.1, 7.28.4.1.2, 7.28.6.3.2, complex, 7.3.7, G.6.3 - 7.28.6.3.3, 7.28.6.4.1, 7.28.6.4.2, J.5.17, real, 7.12.6, F.10.3 - K.3.1.3, K.3.7.4.2 expression, 6.5 -errno.h header, 7.5, 7.30.3, K.3.2 assignment, 6.5.16 -errno_t type, K.3.2, K.3.5, K.3.6, K.3.6.1.1, cast, 6.5.4 - K.3.7, K.3.8, K.3.9 constant, 6.6 -error evaluation, 5.1.2.3 - domain, see domain error full, 6.8 - encoding, see encoding error order of evaluation, see order of evaluation - pole, see pole error parenthesized, 6.5.1 - range, see range error primary, 6.5.1 -error conditions, 7.12.1 unary, 6.5.3 -error functions, 7.12.8, F.10.5 expression statement, 6.8.3 -error indicator, 7.21.1, 7.21.5.3, 7.21.7.1, extended alignment, 6.2.8 - 7.21.7.3, 7.21.7.5, 7.21.7.6, 7.21.7.7, extended character set, 3.7.2, 5.2.1, 5.2.1.2 - 7.21.7.8, 7.21.9.2, 7.21.10.1, 7.21.10.3, extended characters, 5.2.1 - 7.28.3.1, 7.28.3.3 extended integer types, 6.2.5, 6.3.1.1, 6.4.4.1, -error preprocessing directive, 4, 6.10.5 7.20 -error-handling functions, 7.21.10, 7.23.6.2, extended multibyte/wide character conversion - K.3.7.4.2, K.3.7.4.3 utilities, 7.28.6, K.3.9.3 -escape character (\), 6.4.4.4 extensible wide character case mapping functions, -escape sequences, 5.2.1, 5.2.2, 6.4.4.4, 6.11.4 7.29.3.2 -evaluation format, 5.2.4.2.2, 6.4.4.2, 7.12 extensible wide character classification functions, -evaluation method, 5.2.4.2.2, 6.5, F.8.5 7.29.2.2 -evaluation of expression, 5.1.2.3 extern storage-class specifier, 6.2.2, 6.7.1 -evaluation order, see order of evaluation external definition, 6.9 -exceptional condition, 6.5 external identifiers, underscore, 7.1.3 -excess precision, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, external linkage, 6.2.2 - 6.8.6.4 external name, 6.4.2.1 -excess range, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, 6.8.6.4 external object definitions, 6.9.2 -exclusive OR operators - bitwise (^), 6.2.6.2, 6.5.11 fabs functions, 7.12.7.2, F.3, F.10.4.2 - bitwise assignment (^=), 6.5.16.2 fabs type-generic macro, 7.24, G.7 -executable program, 5.1.1.1 false macro, 7.18 -execution character set, 5.2.1 fclose function, 7.21.5.1 -execution environment, 5, 5.1.2, see also fdim functions, 7.12.12.1, F.10.9.1 - environmental limits fdim type-generic macro, 7.24 -execution sequence, 5.1.2.3, 6.8 FE_ALL_EXCEPT macro, 7.6 -exit function, 5.1.2.2.3, 7.21.3, 7.22, 7.22.4.4, FE_DFL_ENV macro, 7.6 - 7.22.4.5, 7.22.4.7 FE_DIVBYZERO macro, 7.6, 7.12, F.3 -EXIT_FAILURE macro, 7.22, 7.22.4.4 FE_DOWNWARD macro, 7.6, F.3 -EXIT_SUCCESS macro, 7.22, 7.22.4.4 FE_INEXACT macro, 7.6, F.3 -exp functions, 7.12.6.1, F.10.3.1 FE_INVALID macro, 7.6, 7.12, F.3 - -[page 661] - -FE_OVERFLOW macro, 7.6, 7.12, F.3 float _Complex type, 6.2.5 -FE_TONEAREST macro, 7.6, F.3 float _Complex type conversion, 6.3.1.6, -FE_TOWARDZERO macro, 7.6, F.3 6.3.1.7, 6.3.1.8 -FE_UNDERFLOW macro, 7.6, F.3 float _Imaginary type, G.2 -FE_UPWARD macro, 7.6, F.3 float type, 6.2.5, 6.4.4.2, 6.7.2, F.2 -feclearexcept function, 7.6.2, 7.6.2.1, F.3 float type conversion, 6.3.1.4, 6.3.1.5, 6.3.1.7, -fegetenv function, 7.6.4.1, 7.6.4.3, 7.6.4.4, F.3 6.3.1.8 -fegetexceptflag function, 7.6.2, 7.6.2.2, F.3 float.h header, 4, 5.2.4.2.2, 7.7, 7.22.1.3, -fegetround function, 7.6, 7.6.3.1, F.3 7.28.4.1.1 -feholdexcept function, 7.6.4.2, 7.6.4.3, float_t type, 7.12, J.5.6 - 7.6.4.4, F.3 floating constant, 6.4.4.2 -fence, 5.1.2.4 floating suffix, f or F, 6.4.4.2 -fences, 7.17.4 floating type conversion, 6.3.1.4, 6.3.1.5, 6.3.1.7, -fenv.h header, 5.1.2.3, 5.2.4.2.2, 7.6, 7.12, F, H F.3, F.4 -FENV_ACCESS pragma, 6.10.6, 7.6.1, F.8, F.9, floating types, 6.2.5, 6.11.1 - F.10 floating-point accuracy, 5.2.4.2.2, 6.4.4.2, 6.5, -fenv_t type, 7.6 7.22.1.3, F.5, see also contracted expression -feof function, 7.21.10.2 floating-point arithmetic functions, 7.12, F.10 -feraiseexcept function, 7.6.2, 7.6.2.3, F.3 floating-point classification functions, 7.12.3 -ferror function, 7.21.10.3 floating-point control mode, 7.6, F.8.6 -fesetenv function, 7.6.4.3, F.3 floating-point environment, 7.6, F.8, F.8.6 -fesetexceptflag function, 7.6.2, 7.6.2.4, F.3 floating-point exception, 7.6, 7.6.2, F.10 -fesetround function, 7.6, 7.6.3.2, F.3 floating-point number, 5.2.4.2.2, 6.2.5 -fetestexcept function, 7.6.2, 7.6.2.5, F.3 floating-point rounding mode, 5.2.4.2.2 -feupdateenv function, 7.6.4.2, 7.6.4.4, F.3 floating-point status flag, 7.6, F.8.6 -fexcept_t type, 7.6, F.3 floor functions, 7.12.9.2, F.10.6.2 -fflush function, 7.21.5.2, 7.21.5.3 floor type-generic macro, 7.24 -fgetc function, 7.21.1, 7.21.3, 7.21.7.1, FLT_DECIMAL_DIG macro, 5.2.4.2.2 - 7.21.7.5, 7.21.8.1 FLT_DIG macro, 5.2.4.2.2 -fgetpos function, 7.21.2, 7.21.9.1, 7.21.9.3 FLT_EPSILON macro, 5.2.4.2.2 -fgets function, 7.21.1, 7.21.7.2, K.3.5.4.1 FLT_EVAL_METHOD macro, 5.2.4.2.2, 6.6, 7.12, -fgetwc function, 7.21.1, 7.21.3, 7.28.3.1, F.10.11 - 7.28.3.6 FLT_HAS_SUBNORM macro, 5.2.4.2.2 -fgetws function, 7.21.1, 7.28.3.2 FLT_MANT_DIG macro, 5.2.4.2.2 -field width, 7.21.6.1, 7.28.2.1 FLT_MAX macro, 5.2.4.2.2 -file, 7.21.3 FLT_MAX_10_EXP macro, 5.2.4.2.2 - access functions, 7.21.5, K.3.5.2 FLT_MAX_EXP macro, 5.2.4.2.2 - name, 7.21.3 FLT_MIN macro, 5.2.4.2.2 - operations, 7.21.4, K.3.5.1 FLT_MIN_10_EXP macro, 5.2.4.2.2 - position indicator, 7.21.1, 7.21.2, 7.21.3, FLT_MIN_EXP macro, 5.2.4.2.2 - 7.21.5.3, 7.21.7.1, 7.21.7.3, 7.21.7.10, FLT_RADIX macro, 5.2.4.2.2, 7.21.6.1, 7.22.1.3, - 7.21.8.1, 7.21.8.2, 7.21.9.1, 7.21.9.2, 7.28.2.1, 7.28.4.1.1 - 7.21.9.3, 7.21.9.4, 7.21.9.5, 7.28.3.1, FLT_ROUNDS macro, 5.2.4.2.2, 7.6, F.3 - 7.28.3.3, 7.28.3.10 FLT_TRUE_MIN macro, 5.2.4.2.2 - positioning functions, 7.21.9 fma functions, 7.12, 7.12.13.1, F.10.10.1 -file scope, 6.2.1, 6.9 fma type-generic macro, 7.24 -FILE type, 7.21.1, 7.21.3 fmax functions, 7.12.12.2, F.10.9.2 -FILENAME_MAX macro, 7.21.1 fmax type-generic macro, 7.24 -flags, 7.21.6.1, 7.28.2.1, see also floating-point fmin functions, 7.12.12.3, F.10.9.3 - status flag fmin type-generic macro, 7.24 -flexible array member, 6.7.2.1 fmod functions, 7.12.10.1, F.10.7.1 - -[page 662] - -fmod type-generic macro, 7.24 fscanf_s function, K.3.5.3.2, K.3.5.3.4, -fopen function, 7.21.5.3, 7.21.5.4, K.3.5.2.1 K.3.5.3.7, K.3.5.3.9 -FOPEN_MAX macro, 7.21.1, 7.21.3, 7.21.4.3, fseek function, 7.21.1, 7.21.5.3, 7.21.7.10, - K.3.5.1.1 7.21.9.2, 7.21.9.4, 7.21.9.5, 7.28.3.10 -fopen_s function, K.3.5.1.1, K.3.5.2.1, fsetpos function, 7.21.2, 7.21.5.3, 7.21.7.10, - K.3.5.2.2 7.21.9.1, 7.21.9.3, 7.28.3.10 -for statement, 6.8.5, 6.8.5.3 ftell function, 7.21.9.2, 7.21.9.4 -form-feed character, 5.2.1, 6.4 full declarator, 6.7.6 -form-feed escape sequence (\f), 5.2.2, 6.4.4.4, full expression, 6.8 - 7.4.1.10 fully buffered stream, 7.21.3 -formal argument (deprecated), 3.16 function -formal parameter, 3.16 argument, 6.5.2.2, 6.9.1 -formatted input/output functions, 7.11.1.1, 7.21.6, body, 6.9.1 - K.3.5.3 call, 6.5.2.2 - wide character, 7.28.2, K.3.9.1 library, 7.1.4 -fortran keyword, J.5.9 declarator, 6.7.6.3, 6.11.6 -forward reference, 3.11 definition, 6.7.6.3, 6.9.1, 6.11.7 -FP_CONTRACT pragma, 6.5, 6.10.6, 7.12.2, see designator, 6.3.2.1 - also contracted expression image, 5.2.3 -FP_FAST_FMA macro, 7.12 inline, 6.7.4 -FP_FAST_FMAF macro, 7.12 library, 5.1.1.1, 7.1.4 -FP_FAST_FMAL macro, 7.12 name length, 5.2.4.1, 6.4.2.1, 6.11.3 -FP_ILOGB0 macro, 7.12, 7.12.6.5 no-return, 6.7.4 -FP_ILOGBNAN macro, 7.12, 7.12.6.5 parameter, 5.1.2.2.1, 6.5.2.2, 6.7, 6.9.1 -FP_INFINITE macro, 7.12, F.3 prototype, 5.1.2.2.1, 6.2.1, 6.2.7, 6.5.2.2, 6.7, -FP_NAN macro, 7.12, F.3 6.7.6.3, 6.9.1, 6.11.6, 6.11.7, 7.1.2, 7.12 -FP_NORMAL macro, 7.12, F.3 prototype scope, 6.2.1, 6.7.6.2 -FP_SUBNORMAL macro, 7.12, F.3 recursive call, 6.5.2.2 -FP_ZERO macro, 7.12, F.3 return, 6.8.6.4, F.6 -fpclassify macro, 7.12.3.1, F.3 scope, 6.2.1 -fpos_t type, 7.21.1, 7.21.2 type, 6.2.5 -fprintf function, 7.8.1, 7.21.1, 7.21.6.1, type conversion, 6.3.2.1 - 7.21.6.2, 7.21.6.3, 7.21.6.5, 7.21.6.6, function specifiers, 6.7.4 - 7.21.6.8, 7.28.2.2, F.3, K.3.5.3.1 function type, 6.2.5 -fprintf_s function, K.3.5.3.1 function-call operator (( )), 6.5.2.2 -fputc function, 5.2.2, 7.21.1, 7.21.3, 7.21.7.3, function-like macro, 6.10.3 - 7.21.7.7, 7.21.8.2 fundamental alignment, 6.2.8 -fputs function, 7.21.1, 7.21.7.4 future directions -fputwc function, 7.21.1, 7.21.3, 7.28.3.3, language, 6.11 - 7.28.3.8 library, 7.30 -fputws function, 7.21.1, 7.28.3.4 fwide function, 7.21.2, 7.28.3.5 -fread function, 7.21.1, 7.21.8.1 fwprintf function, 7.8.1, 7.21.1, 7.21.6.2, -free function, 7.22.3.3, 7.22.3.5 7.28.2.1, 7.28.2.2, 7.28.2.3, 7.28.2.5, -freestanding execution environment, 4, 5.1.2, 7.28.2.11, K.3.9.1.1 - 5.1.2.1 fwprintf_s function, K.3.9.1.1 -freopen function, 7.21.2, 7.21.5.4 fwrite function, 7.21.1, 7.21.8.2 -freopen_s function, K.3.5.2.2 fwscanf function, 7.8.1, 7.21.1, 7.28.2.2, -frexp functions, 7.12.6.4, F.10.3.4 7.28.2.4, 7.28.2.6, 7.28.2.12, 7.28.3.10, -frexp type-generic macro, 7.24 K.3.9.1.2 -fscanf function, 7.8.1, 7.21.1, 7.21.6.2, fwscanf_s function, K.3.9.1.2, K.3.9.1.5, - 7.21.6.4, 7.21.6.7, 7.21.6.9, F.3, K.3.5.3.2 K.3.9.1.7, K.3.9.1.14 - -[page 663] - -gamma functions, 7.12.8, F.10.5 name spaces, 6.2.3 -general utilities, 7.22, K.3.6 reserved, 6.4.1, 7.1.3, K.3.1.2 - wide string, 7.28.4, K.3.9.2 scope, 6.2.1 -general wide string utilities, 7.28.4, K.3.9.2 type, 6.2.5 -generic parameters, 7.24 identifier list, 6.7.6 -generic selection, 6.5.1.1 identifier nondigit, 6.4.2.1 -getc function, 7.21.1, 7.21.7.5, 7.21.7.6 IEC 559, F.1 -getchar function, 7.21.1, 7.21.7.6 IEC 60559, 2, 5.1.2.3, 5.2.4.2.2, 6.10.8.3, 7.3.3, -getenv function, 7.22.4.6 7.6, 7.6.4.2, 7.12.1, 7.12.10.2, 7.12.14, F, G, -getenv_s function, K.3.6.2.1 H.1 -gets function, K.3.5.4.1 IEEE 754, F.1 -gets_s function, K.3.5.4.1 IEEE 854, F.1 -getwc function, 7.21.1, 7.28.3.6, 7.28.3.7 IEEE floating-point arithmetic standard, see -getwchar function, 7.21.1, 7.28.3.7 IEC 60559, ANSI/IEEE 754, -gmtime function, 7.26.3.3 ANSI/IEEE 854 -gmtime_s function, K.3.8.2.3 if preprocessing directive, 5.2.4.2.1, 5.2.4.2.2, -goto statement, 6.2.1, 6.8.1, 6.8.6.1 6.10.1, 7.1.4 -graphic characters, 5.2.1 if statement, 6.8.4.1 -greater-than operator (>), 6.5.8 ifdef preprocessing directive, 6.10.1 -greater-than-or-equal-to operator (>=), 6.5.8 ifndef preprocessing directive, 6.10.1 - ignore_handler_s function, K.3.6.1.3 -happens before, 5.1.2.4 ilogb functions, 7.12, 7.12.6.5, F.10.3.5 -header, 5.1.1.1, 7.1.2, see also standard headers ilogb type-generic macro, 7.24 -header names, 6.4, 6.4.7, 6.10.2 imaginary macro, 7.3.1, G.6 -hexadecimal constant, 6.4.4.1 imaginary numbers, G -hexadecimal digit, 6.4.4.1, 6.4.4.2, 6.4.4.4 imaginary type domain, G.2 -hexadecimal prefix, 6.4.4.1 imaginary types, G -hexadecimal-character escape sequence imaxabs function, 7.8.2.1 - (\x hexadecimal digits), 6.4.4.4 imaxdiv function, 7.8, 7.8.2.2 -high-order bit, 3.6 imaxdiv_t type, 7.8 -horizontal-tab character, 5.2.1, 6.4 implementation, 3.12 -horizontal-tab escape sequence (\r), 7.29.2.1.3 implementation limit, 3.13, 4, 5.2.4.2, 6.4.2.1, -horizontal-tab escape sequence (\t), 5.2.2, 6.7.6, 6.8.4.2, E, see also environmental - 6.4.4.4, 7.4.1.3, 7.4.1.10 limits -hosted execution environment, 4, 5.1.2, 5.1.2.2 implementation-defined behavior, 3.4.1, 4, J.3 -HUGE_VAL macro, 7.12, 7.12.1, 7.22.1.3, implementation-defined value, 3.19.1 - 7.28.4.1.1, F.10 implicit conversion, 6.3 -HUGE_VALF macro, 7.12, 7.12.1, 7.22.1.3, implicit initialization, 6.7.9 - 7.28.4.1.1, F.10 include preprocessing directive, 5.1.1.2, 6.10.2 -HUGE_VALL macro, 7.12, 7.12.1, 7.22.1.3, inclusive OR operators - 7.28.4.1.1, F.10 bitwise (|), 6.2.6.2, 6.5.12 -hyperbolic functions bitwise assignment (|=), 6.5.16.2 - complex, 7.3.6, G.6.2 incomplete type, 6.2.5 - real, 7.12.5, F.10.2 increment operators, see arithmetic operators, -hypot functions, 7.12.7.3, F.10.4.3 increment and decrement -hypot type-generic macro, 7.24 indeterminate value, 3.19.2 - indeterminately sequenced, 5.1.2.3, 6.5.2.2, -I macro, 7.3.1, 7.3.9.5, G.6 6.5.2.4, 6.5.16.2, see also sequenced before, -identifier, 6.4.2.1, 6.5.1 unsequenced - linkage, see linkage indirection operator (*), 6.5.2.1, 6.5.3.2 - maximum length, 6.4.2.1 inequality operator (!=), 6.5.9 - -[page 664] - -infinitary, 7.12.1 extended, 6.2.5, 6.3.1.1, 6.4.4.1, 7.20 -INFINITY macro, 7.3.9.5, 7.12, F.2.1 inter-thread happens before, 5.1.2.4 -initial position, 5.2.2 interactive device, 5.1.2.3, 7.21.3, 7.21.5.3 -initial shift state, 5.2.1.2 internal linkage, 6.2.2 -initialization, 5.1.2, 6.2.4, 6.3.2.1, 6.5.2.5, 6.7.9, internal name, 6.4.2.1 - F.8.5 interrupt, 5.2.3 - in blocks, 6.8 INTMAX_C macro, 7.20.4.2 -initializer, 6.7.9 INTMAX_MAX macro, 7.8.2.3, 7.8.2.4, 7.20.2.5 - permitted form, 6.6 INTMAX_MIN macro, 7.8.2.3, 7.8.2.4, 7.20.2.5 - string literal, 6.3.2.1 intmax_t type, 7.20.1.5, 7.21.6.1, 7.21.6.2, -inline, 6.7.4 7.28.2.1, 7.28.2.2 -inner scope, 6.2.1 INTN_C macros, 7.20.4.1 -input failure, 7.28.2.6, 7.28.2.8, 7.28.2.10, INTN_MAX macros, 7.20.2.1 - K.3.5.3.2, K.3.5.3.4, K.3.5.3.7, K.3.5.3.9, INTN_MIN macros, 7.20.2.1 - K.3.5.3.11, K.3.5.3.14, K.3.9.1.2, K.3.9.1.5, intN_t types, 7.20.1.1 - K.3.9.1.7, K.3.9.1.10, K.3.9.1.12, K.3.9.1.14 INTPTR_MAX macro, 7.20.2.4 -input/output functions INTPTR_MIN macro, 7.20.2.4 - character, 7.21.7, K.3.5.4 intptr_t type, 7.20.1.4 - direct, 7.21.8 inttypes.h header, 7.8, 7.30.4 - formatted, 7.21.6, K.3.5.3 isalnum function, 7.4.1.1, 7.4.1.9, 7.4.1.10 - wide character, 7.28.2, K.3.9.1 isalpha function, 7.4.1.1, 7.4.1.2 - wide character, 7.28.3 isblank function, 7.4.1.3 - formatted, 7.28.2, K.3.9.1 iscntrl function, 7.4.1.2, 7.4.1.4, 7.4.1.7, -input/output header, 7.21, K.3.5 7.4.1.11 -input/output, device, 5.1.2.3 isdigit function, 7.4.1.1, 7.4.1.2, 7.4.1.5, -int type, 6.2.5, 6.3.1.1, 6.3.1.3, 6.4.4.1, 6.7.2 7.4.1.7, 7.4.1.11, 7.11.1.1 -int type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4, isfinite macro, 7.12.3.2, F.3 - 6.3.1.8 isgraph function, 7.4.1.6 -INT_FASTN_MAX macros, 7.20.2.3 isgreater macro, 7.12.14.1, F.3 -INT_FASTN_MIN macros, 7.20.2.3 isgreaterequal macro, 7.12.14.2, F.3 -int_fastN_t types, 7.20.1.3 isinf macro, 7.12.3.3 -INT_LEASTN_MAX macros, 7.20.2.2 isless macro, 7.12.14.3, F.3 -INT_LEASTN_MIN macros, 7.20.2.2 islessequal macro, 7.12.14.4, F.3 -int_leastN_t types, 7.20.1.2 islessgreater macro, 7.12.14.5, F.3 -INT_MAX macro, 5.2.4.2.1, 7.12, 7.12.6.5 islower function, 7.4.1.2, 7.4.1.7, 7.4.2.1, -INT_MIN macro, 5.2.4.2.1, 7.12 7.4.2.2 -integer arithmetic functions, 7.8.2.1, 7.8.2.2, isnan macro, 7.12.3.4, F.3 - 7.22.6 isnormal macro, 7.12.3.5 -integer character constant, 6.4.4.4 ISO 31-11, 2, 3 -integer constant, 6.4.4.1 ISO 4217, 2, 7.11.2.1 -integer constant expression, 6.3.2.3, 6.6, 6.7.2.1, ISO 8601, 2, 7.26.3.5 - 6.7.2.2, 6.7.6.2, 6.7.9, 6.7.10, 6.8.4.2, 6.10.1, ISO/IEC 10646, 2, 6.4.2.1, 6.4.3, 6.10.8.2 - 7.1.4 ISO/IEC 10976-1, H.1 -integer conversion rank, 6.3.1.1 ISO/IEC 2382-1, 2, 3 -integer promotions, 5.1.2.3, 5.2.4.2.1, 6.3.1.1, ISO/IEC 646, 2, 5.2.1.1 - 6.5.2.2, 6.5.3.3, 6.5.7, 6.8.4.2, 7.20.2, 7.20.3, ISO/IEC 9945-2, 7.11 - 7.21.6.1, 7.28.2.1 ISO/IEC TR 10176, D -integer suffix, 6.4.4.1 iso646.h header, 4, 7.9 -integer type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4, isprint function, 5.2.2, 7.4.1.8 - F.3, F.4 ispunct function, 7.4.1.2, 7.4.1.7, 7.4.1.9, -integer types, 6.2.5, 7.20 7.4.1.11 - -[page 665] - -isspace function, 7.4.1.2, 7.4.1.7, 7.4.1.9, Latin alphabet, 5.2.1, 6.4.2.1 - 7.4.1.10, 7.4.1.11, 7.21.6.2, 7.22.1.3, LC_ALL macro, 7.11, 7.11.1.1, 7.11.2.1 - 7.22.1.4, 7.28.2.2 LC_COLLATE macro, 7.11, 7.11.1.1, 7.23.4.3, -isunordered macro, 7.12.14.6, F.3 7.28.4.4.2 -isupper function, 7.4.1.2, 7.4.1.11, 7.4.2.1, LC_CTYPE macro, 7.11, 7.11.1.1, 7.22, 7.22.7, - 7.4.2.2 7.22.8, 7.28.6, 7.29.1, 7.29.2.2.1, 7.29.2.2.2, -iswalnum function, 7.29.2.1.1, 7.29.2.1.9, 7.29.3.2.1, 7.29.3.2.2, K.3.6.4, K.3.6.5 - 7.29.2.1.10, 7.29.2.2.1 LC_MONETARY macro, 7.11, 7.11.1.1, 7.11.2.1 -iswalpha function, 7.29.2.1.1, 7.29.2.1.2, LC_NUMERIC macro, 7.11, 7.11.1.1, 7.11.2.1 - 7.29.2.2.1 LC_TIME macro, 7.11, 7.11.1.1, 7.26.3.5 -iswblank function, 7.29.2.1.3, 7.29.2.2.1 lconv structure type, 7.11 -iswcntrl function, 7.29.2.1.2, 7.29.2.1.4, LDBL_DECIMAL_DIG macro, 5.2.4.2.2 - 7.29.2.1.7, 7.29.2.1.11, 7.29.2.2.1 LDBL_DIG macro, 5.2.4.2.2 -iswctype function, 7.29.2.2.1, 7.29.2.2.2 LDBL_EPSILON macro, 5.2.4.2.2 -iswdigit function, 7.29.2.1.1, 7.29.2.1.2, LDBL_HAS_SUBNORM macro, 5.2.4.2.2 - 7.29.2.1.5, 7.29.2.1.7, 7.29.2.1.11, 7.29.2.2.1 LDBL_MANT_DIG macro, 5.2.4.2.2 -iswgraph function, 7.29.2.1, 7.29.2.1.6, LDBL_MAX macro, 5.2.4.2.2 - 7.29.2.1.10, 7.29.2.2.1 LDBL_MAX_10_EXP macro, 5.2.4.2.2 -iswlower function, 7.29.2.1.2, 7.29.2.1.7, LDBL_MAX_EXP macro, 5.2.4.2.2 - 7.29.2.2.1, 7.29.3.1.1, 7.29.3.1.2 LDBL_MIN macro, 5.2.4.2.2 -iswprint function, 7.29.2.1.6, 7.29.2.1.8, LDBL_MIN_10_EXP macro, 5.2.4.2.2 - 7.29.2.2.1 LDBL_MIN_EXP macro, 5.2.4.2.2 -iswpunct function, 7.29.2.1, 7.29.2.1.2, LDBL_TRUE_MIN macro, 5.2.4.2.2 - 7.29.2.1.7, 7.29.2.1.9, 7.29.2.1.10, ldexp functions, 7.12.6.6, F.10.3.6 - 7.29.2.1.11, 7.29.2.2.1 ldexp type-generic macro, 7.24 -iswspace function, 7.21.6.2, 7.28.2.2, ldiv function, 7.22.6.2 - 7.28.4.1.1, 7.28.4.1.2, 7.29.2.1.2, 7.29.2.1.6, ldiv_t type, 7.22 - 7.29.2.1.7, 7.29.2.1.9, 7.29.2.1.10, leading underscore in identifiers, 7.1.3 - 7.29.2.1.11, 7.29.2.2.1 left-shift assignment operator (<<=), 6.5.16.2 -iswupper function, 7.29.2.1.2, 7.29.2.1.11, left-shift operator (<<), 6.2.6.2, 6.5.7 - 7.29.2.2.1, 7.29.3.1.1, 7.29.3.1.2 length -iswxdigit function, 7.29.2.1.12, 7.29.2.2.1 external name, 5.2.4.1, 6.4.2.1, 6.11.3 -isxdigit function, 7.4.1.12, 7.11.1.1 function name, 5.2.4.1, 6.4.2.1, 6.11.3 -italic type convention, 3, 6.1 identifier, 6.4.2.1 -iteration statements, 6.8.5 internal name, 5.2.4.1, 6.4.2.1 - length function, 7.22.7.1, 7.23.6.3, 7.28.4.6.1, -jmp_buf type, 7.13 7.28.6.3.1, K.3.7.4.4, K.3.9.2.4.1 -jump statements, 6.8.6 length modifier, 7.21.6.1, 7.21.6.2, 7.28.2.1, - 7.28.2.2 -keywords, 6.4.1, G.2, J.5.9, J.5.10 less-than operator (<), 6.5.8 -kill_dependency macro, 5.1.2.4, 7.17.3.1 less-than-or-equal-to operator (<=), 6.5.8 -known constant size, 6.2.5 letter, 5.2.1, 7.4 - lexical elements, 5.1.1.2, 6.4 -L_tmpnam macro, 7.21.1, 7.21.4.4 lgamma functions, 7.12.8.3, F.10.5.3 -L_tmpnam_s macro, K.3.5, K.3.5.1.2 lgamma type-generic macro, 7.24 -label name, 6.2.1, 6.2.3 library, 5.1.1.1, 7, K.3 -labeled statement, 6.8.1 future directions, 7.30 -labs function, 7.22.6.1 summary, B -language, 6 terms, 7.1.1 - future directions, 6.11 use of functions, 7.1.4 - syntax summary, A lifetime, 6.2.4 - -[page 666] - -limits long double _Complex type conversion, - environmental, see environmental limits 6.3.1.6, 6.3.1.7, 6.3.1.8 - implementation, see implementation limits long double _Imaginary type, G.2 - numerical, see numerical limits long double suffix, l or L, 6.4.4.2 - translation, see translation limits long double type, 6.2.5, 6.4.4.2, 6.7.2, -limits.h header, 4, 5.2.4.2.1, 6.2.5, 7.10 7.21.6.1, 7.21.6.2, 7.28.2.1, 7.28.2.2, F.2 -line buffered stream, 7.21.3 long double type conversion, 6.3.1.4, 6.3.1.5, -line number, 6.10.4, 6.10.8.1 6.3.1.7, 6.3.1.8 -line preprocessing directive, 6.10.4 long int type, 6.2.5, 6.3.1.1, 6.7.2, 7.21.6.1, -lines, 5.1.1.2, 7.21.2 7.21.6.2, 7.28.2.1, 7.28.2.2 - preprocessing directive, 6.10 long int type conversion, 6.3.1.1, 6.3.1.3, -linkage, 6.2.2, 6.7, 6.7.4, 6.7.6.2, 6.9, 6.9.2, 6.3.1.4, 6.3.1.8 - 6.11.2 long integer suffix, l or L, 6.4.4.1 -llabs function, 7.22.6.1 long long int type, 6.2.5, 6.3.1.1, 6.7.2, -lldiv function, 7.22.6.2 7.21.6.1, 7.21.6.2, 7.28.2.1, 7.28.2.2 -lldiv_t type, 7.22 long long int type conversion, 6.3.1.1, -LLONG_MAX macro, 5.2.4.2.1, 7.22.1.4, 6.3.1.3, 6.3.1.4, 6.3.1.8 - 7.28.4.1.2 long long integer suffix, ll or LL, 6.4.4.1 -LLONG_MIN macro, 5.2.4.2.1, 7.22.1.4, LONG_MAX macro, 5.2.4.2.1, 7.22.1.4, 7.28.4.1.2 - 7.28.4.1.2 LONG_MIN macro, 5.2.4.2.1, 7.22.1.4, 7.28.4.1.2 -llrint functions, 7.12.9.5, F.3, F.10.6.5 longjmp function, 7.13.1.1, 7.13.2.1, 7.22.4.4, -llrint type-generic macro, 7.24 7.22.4.7 -llround functions, 7.12.9.7, F.10.6.7 loop body, 6.8.5 -llround type-generic macro, 7.24 low-order bit, 3.6 -local time, 7.26.1 lowercase letter, 5.2.1 -locale, 3.4.2 lrint functions, 7.12.9.5, F.3, F.10.6.5 -locale-specific behavior, 3.4.2, J.4 lrint type-generic macro, 7.24 -locale.h header, 7.11, 7.30.5 lround functions, 7.12.9.7, F.10.6.7 -localeconv function, 7.11.1.1, 7.11.2.1 lround type-generic macro, 7.24 -localization, 7.11 lvalue, 6.3.2.1, 6.5.1, 6.5.2.4, 6.5.3.1, 6.5.16 -localtime function, 7.26.3.4 -localtime_s function, K.3.8.2.4 macro argument substitution, 6.10.3.1 -log functions, 7.12.6.7, F.10.3.7 macro definition -log type-generic macro, 7.24 library function, 7.1.4 -log10 functions, 7.12.6.8, F.10.3.8 macro invocation, 6.10.3 -log10 type-generic macro, 7.24 macro name, 6.10.3 -log1p functions, 7.12.6.9, F.10.3.9 length, 5.2.4.1 -log1p type-generic macro, 7.24 predefined, 6.10.8, 6.11.9 -log2 functions, 7.12.6.10, F.10.3.10 redefinition, 6.10.3 -log2 type-generic macro, 7.24 scope, 6.10.3.5 -logarithmic functions macro parameter, 6.10.3 - complex, 7.3.7, G.6.3 macro preprocessor, 6.10 - real, 7.12.6, F.10.3 macro replacement, 6.10.3 -logb functions, 7.12.6.11, F.3, F.10.3.11 magnitude, complex, 7.3.8.1 -logb type-generic macro, 7.24 main function, 5.1.2.2.1, 5.1.2.2.3, 6.7.3.1, 6.7.4, -logical operators 7.21.3 - AND (&&), 5.1.2.4, 6.5.13 malloc function, 7.22.3, 7.22.3.4, 7.22.3.5 - negation (!), 6.5.3.3 manipulation functions - OR (||), 5.1.2.4, 6.5.14 complex, 7.3.9 -logical source lines, 5.1.1.2 real, 7.12.11, F.10.8 -long double _Complex type, 6.2.5 matching failure, 7.28.2.6, 7.28.2.8, 7.28.2.10, - -[page 667] - - K.3.9.1.7, K.3.9.1.10, K.3.9.1.12 modification order, 5.1.2.4 -math.h header, 5.2.4.2.2, 6.5, 7.12, 7.24, F, modulus functions, 7.12.6.12 - F.10, J.5.17 modulus, complex, 7.3.8.1 -MATH_ERREXCEPT macro, 7.12, F.10 mtx_destroy function, 7.25.4.1 -math_errhandling macro, 7.1.3, 7.12, F.10 mtx_init function, 7.25.1, 7.25.4.2 -MATH_ERRNO macro, 7.12 mtx_lock function, 7.25.4.3 -max_align_t type, 7.19 mtx_t type, 7.25.1 -maximum functions, 7.12.12, F.10.9 mtx_timedlock function, 7.25.4.4 -MB_CUR_MAX macro, 7.1.1, 7.22, 7.22.7.2, mtx_trylock function, 7.25.4.5 - 7.22.7.3, 7.27.1.2, 7.27.1.4, 7.28.6.3.3, mtx_unlock function, 7.25.4.3, 7.25.4.4, - K.3.6.4.1, K.3.9.3.1.1 7.25.4.5, 7.25.4.6 -MB_LEN_MAX macro, 5.2.4.2.1, 7.1.1, 7.22 multibyte character, 3.7.2, 5.2.1.2, 6.4.4.4 -mblen function, 7.22.7.1, 7.28.6.3 multibyte conversion functions -mbrlen function, 7.28.6.3.1 wide character, 7.22.7, K.3.6.4 -mbrtoc16 function, 6.4.4.4, 6.4.5, 7.27.1.1 extended, 7.28.6, K.3.9.3 -mbrtoc32 function, 6.4.4.4, 6.4.5, 7.27.1.3 restartable, 7.27.1, 7.28.6.3, K.3.9.3.1 -mbrtowc function, 7.21.3, 7.21.6.1, 7.21.6.2, wide string, 7.22.8, K.3.6.5 - 7.28.2.1, 7.28.2.2, 7.28.6.3.1, 7.28.6.3.2, restartable, 7.28.6.4, K.3.9.3.2 - 7.28.6.4.1, K.3.6.5.1, K.3.9.3.2.1 multibyte string, 7.1.1 -mbsinit function, 7.28.6.2.1 multibyte/wide character conversion functions, -mbsrtowcs function, 7.28.6.4.1, K.3.9.3.2 7.22.7, K.3.6.4 -mbsrtowcs_s function, K.3.9.3.2, K.3.9.3.2.1 extended, 7.28.6, K.3.9.3 -mbstate_t type, 7.21.2, 7.21.3, 7.21.6.1, restartable, 7.27.1, 7.28.6.3, K.3.9.3.1 - 7.21.6.2, 7.27, 7.27.1, 7.28.1, 7.28.2.1, multibyte/wide string conversion functions, - 7.28.2.2, 7.28.6, 7.28.6.2.1, 7.28.6.3, 7.22.8, K.3.6.5 - 7.28.6.3.1, 7.28.6.4 restartable, 7.28.6.4, K.3.9.3.2 -mbstowcs function, 6.4.5, 7.22.8.1, 7.28.6.4 multidimensional array, 6.5.2.1 -mbstowcs_s function, K.3.6.5.1 multiplication assignment operator (*=), 6.5.16.2 -mbtowc function, 6.4.4.4, 7.22.7.1, 7.22.7.2, multiplication operator (*), 6.2.6.2, 6.5.5, F.3, - 7.22.8.1, 7.28.6.3 G.5.1 -member access operators (. and ->), 6.5.2.3 multiplicative expressions, 6.5.5, G.5.1 -member alignment, 6.7.2.1 -memchr function, 7.23.5.1 n-char sequence, 7.22.1.3 -memcmp function, 7.23.4, 7.23.4.1 n-wchar sequence, 7.28.4.1.1 -memcpy function, 7.23.2.1 name -memcpy_s function, K.3.7.1.1 external, 5.2.4.1, 6.4.2.1, 6.11.3 -memmove function, 7.23.2.2 file, 7.21.3 -memmove_s function, K.3.7.1.2 internal, 5.2.4.1, 6.4.2.1 -memory location, 3.14 label, 6.2.3 -memory management functions, 7.22.3 structure/union member, 6.2.3 -memory_order type, 7.17.1, 7.17.3 name spaces, 6.2.3 -memset function, 7.23.6.1, K.3.7.4.1 named label, 6.8.1 -memset_s function, K.3.7.4.1 NaN, 5.2.4.2.2 -minimum functions, 7.12.12, F.10.9 nan functions, 7.12.11.2, F.2.1, F.10.8.2 -minus operator, unary, 6.5.3.3 NAN macro, 7.12, F.2.1 -miscellaneous functions NDEBUG macro, 7.2 - string, 7.23.6, K.3.7.4 nearbyint functions, 7.12.9.3, 7.12.9.4, F.3, - wide string, 7.28.4.6, K.3.9.2.4 F.10.6.3 -mktime function, 7.26.2.3 nearbyint type-generic macro, 7.24 -modf functions, 7.12.6.12, F.10.3.12 nearest integer functions, 7.12.9, F.10.6 -modifiable lvalue, 6.3.2.1 negation operator (!), 6.5.3.3 - -[page 668] - -negative zero, 6.2.6.2, 7.12.11.1 operator, 6.4.6 -new-line character, 5.1.1.2, 5.2.1, 6.4, 6.10, 6.10.4 operators, 6.5 -new-line escape sequence (\n), 5.2.2, 6.4.4.4, additive, 6.2.6.2, 6.5.6 - 7.4.1.10 alignof, 6.5.3.4 -nextafter functions, 7.12.11.3, 7.12.11.4, F.3, assignment, 6.5.16 - F.10.8.3 associativity, 6.5 -nextafter type-generic macro, 7.24 equality, 6.5.9 -nexttoward functions, 7.12.11.4, F.3, F.10.8.4 multiplicative, 6.2.6.2, 6.5.5, G.5.1 -nexttoward type-generic macro, 7.24 postfix, 6.5.2 -no linkage, 6.2.2 precedence, 6.5 -no-return function, 6.7.4 preprocessing, 6.10.1, 6.10.3.2, 6.10.3.3, 6.10.9 -non-stop floating-point control mode, 7.6.4.2 relational, 6.5.8 -nongraphic characters, 5.2.2, 6.4.4.4 shift, 6.5.7 -nonlocal jumps header, 7.13 sizeof, 6.5.3.4 -norm, complex, 7.3.8.1 unary, 6.5.3 -normalized broken-down time, K.3.8.1, K.3.8.2.1 unary arithmetic, 6.5.3.3 -not macro, 7.9 optional features, see conditional features -not-equal-to operator, see inequality operator or macro, 7.9 -not_eq macro, 7.9 OR operators -null character (\0), 5.2.1, 6.4.4.4, 6.4.5 bitwise exclusive (^), 6.2.6.2, 6.5.11 - padding of binary stream, 7.21.2 bitwise exclusive assignment (^=), 6.5.16.2 -NULL macro, 7.11, 7.19, 7.21.1, 7.22, 7.23.1, bitwise inclusive (|), 6.2.6.2, 6.5.12 - 7.26.1, 7.28.1 bitwise inclusive assignment (|=), 6.5.16.2 -null pointer, 6.3.2.3 logical (||), 5.1.2.4, 6.5.14 -null pointer constant, 6.3.2.3 or_eq macro, 7.9 -null preprocessing directive, 6.10.7 order of allocated storage, 7.22.3 -null statement, 6.8.3 order of evaluation, 6.5, 6.5.16, 6.10.3.2, 6.10.3.3, -null wide character, 7.1.1 see also sequence points -number classification macros, 7.12, 7.12.3.1 ordinary identifier name space, 6.2.3 -numeric conversion functions, 7.8.2.3, 7.22.1 orientation of stream, 7.21.2, 7.28.3.5 - wide string, 7.8.2.4, 7.28.4.1 out-of-bounds store, L.2.1 -numerical limits, 5.2.4.2 outer scope, 6.2.1 - over-aligned, 6.2.8 -object, 3.15 -object representation, 6.2.6.1 padding -object type, 6.2.5 binary stream, 7.21.2 -object-like macro, 6.10.3 bits, 6.2.6.2, 7.20.1.1 -observable behavior, 5.1.2.3 structure/union, 6.2.6.1, 6.7.2.1 -obsolescence, 6.11, 7.30 parameter, 3.16 -octal constant, 6.4.4.1 array, 6.9.1 -octal digit, 6.4.4.1, 6.4.4.4 ellipsis, 6.7.6.3, 6.10.3 -octal-character escape sequence (\octal digits), function, 6.5.2.2, 6.7, 6.9.1 - 6.4.4.4 macro, 6.10.3 -offsetof macro, 7.19 main function, 5.1.2.2.1 -on-off switch, 6.10.6 program, 5.1.2.2.1 -once_flag type, 7.25.1 parameter type list, 6.7.6.3 -ONCE_FLAG_INIT macro, 7.25.1 parentheses punctuator (( )), 6.7.6.3, 6.8.4, 6.8.5 -ones' complement, 6.2.6.2 parenthesized expression, 6.5.1 -operand, 6.4.6, 6.5 parse state, 7.21.2 -operating system, 5.1.2.1, 7.22.4.8 perform a trap, 3.19.5 -operations on files, 7.21.4, K.3.5.1 permitted form of initializer, 6.6 - -[page 669] - -perror function, 7.21.10.4 PRIcLEASTN macros, 7.8.1 -phase angle, complex, 7.3.9.1 PRIcMAX macros, 7.8.1 -physical source lines, 5.1.1.2 PRIcN macros, 7.8.1 -placemarker, 6.10.3.3 PRIcPTR macros, 7.8.1 -plus operator, unary, 6.5.3.3 primary expression, 6.5.1 -pointer arithmetic, 6.5.6 printf function, 7.21.1, 7.21.6.3, 7.21.6.10, -pointer comparison, 6.5.8 K.3.5.3.3 -pointer declarator, 6.7.6.1 printf_s function, K.3.5.3.3 -pointer operator (->), 6.5.2.3 printing character, 5.2.2, 7.4, 7.4.1.8 -pointer to function, 6.5.2.2 printing wide character, 7.29.2 -pointer type, 6.2.5 program diagnostics, 7.2.1 -pointer type conversion, 6.3.2.1, 6.3.2.3 program execution, 5.1.2.2.2, 5.1.2.3 -pointer, null, 6.3.2.3 program file, 5.1.1.1 -pole error, 7.12.1, 7.12.5.3, 7.12.6.7, 7.12.6.8, program image, 5.1.1.2 - 7.12.6.9, 7.12.6.10, 7.12.6.11, 7.12.7.4, program name (argv[0]), 5.1.2.2.1 - 7.12.8.3, 7.12.8.4 program parameters, 5.1.2.2.1 -portability, 4, J program startup, 5.1.2, 5.1.2.1, 5.1.2.2.1 -position indicator, file, see file position indicator program structure, 5.1.1.1 -positive difference, 7.12.12.1 program termination, 5.1.2, 5.1.2.1, 5.1.2.2.3, -positive difference functions, 7.12.12, F.10.9 5.1.2.3 -postfix decrement operator (--), 6.3.2.1, 6.5.2.4 program, conforming, 4 -postfix expressions, 6.5.2 program, strictly conforming, 4 -postfix increment operator (++), 6.3.2.1, 6.5.2.4 promotions -pow functions, 7.12.7.4, F.10.4.4 default argument, 6.5.2.2 -pow type-generic macro, 7.24 integer, 5.1.2.3, 6.3.1.1 -power functions prototype, see function prototype - complex, 7.3.8, G.6.4 pseudo-random sequence functions, 7.22.2 - real, 7.12.7, F.10.4 PTRDIFF_MAX macro, 7.20.3 -pp-number, 6.4.8 PTRDIFF_MIN macro, 7.20.3 -pragma operator, 6.10.9 ptrdiff_t type, 7.17.1, 7.19, 7.20.3, 7.21.6.1, -pragma preprocessing directive, 6.10.6, 6.11.8 7.21.6.2, 7.28.2.1, 7.28.2.2 -precedence of operators, 6.5 punctuators, 6.4.6 -precedence of syntax rules, 5.1.1.2 putc function, 7.21.1, 7.21.7.7, 7.21.7.8 -precision, 6.2.6.2, 6.3.1.1, 7.21.6.1, 7.28.2.1 putchar function, 7.21.1, 7.21.7.8 - excess, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, 6.8.6.4 puts function, 7.21.1, 7.21.7.9 -predefined macro names, 6.10.8, 6.11.9 putwc function, 7.21.1, 7.28.3.8, 7.28.3.9 -prefix decrement operator (--), 6.3.2.1, 6.5.3.1 putwchar function, 7.21.1, 7.28.3.9 -prefix increment operator (++), 6.3.2.1, 6.5.3.1 -preprocessing concatenation, 6.10.3.3 qsort function, 7.22.5, 7.22.5.2 -preprocessing directives, 5.1.1.2, 6.10 qsort_s function, K.3.6.3, K.3.6.3.2 -preprocessing file, 5.1.1.1, 6.10 qualified types, 6.2.5 -preprocessing numbers, 6.4, 6.4.8 qualified version of type, 6.2.5 -preprocessing operators question-mark escape sequence (\?), 6.4.4.4 - #, 6.10.3.2 quick_exit function, 7.22.4.3, 7.22.4.4, - ##, 6.10.3.3 7.22.4.7 - _Pragma, 5.1.1.2, 6.10.9 quiet NaN, 5.2.4.2.2 - defined, 6.10.1 -preprocessing tokens, 5.1.1.2, 6.4, 6.10 raise function, 7.14, 7.14.1.1, 7.14.2.1, 7.22.4.1 -preprocessing translation unit, 5.1.1.1 rand function, 7.22, 7.22.2.1, 7.22.2.2 -preprocessor, 6.10 RAND_MAX macro, 7.22, 7.22.2.1 -PRIcFASTN macros, 7.8.1 range - -[page 670] - - excess, 5.2.4.2.2, 6.3.1.5, 6.3.1.8, 6.8.6.4 rewind function, 7.21.5.3, 7.21.7.10, 7.21.9.5, -range error, 7.12.1, 7.12.5.4, 7.12.5.5, 7.12.6.1, 7.28.3.10 - 7.12.6.2, 7.12.6.3, 7.12.6.5, 7.12.6.6, right-shift assignment operator (>>=), 6.5.16.2 - 7.12.6.13, 7.12.7.3, 7.12.7.4, 7.12.8.2, right-shift operator (>>), 6.2.6.2, 6.5.7 - 7.12.8.3, 7.12.8.4, 7.12.9.5, 7.12.9.7, rint functions, 7.12.9.4, F.3, F.10.6.4 - 7.12.11.3, 7.12.12.1, 7.12.13.1 rint type-generic macro, 7.24 -rank, see integer conversion rank round functions, 7.12.9.6, F.10.6.6 -read-modify-write operations, 5.1.2.4 round type-generic macro, 7.24 -real floating type conversion, 6.3.1.4, 6.3.1.5, rounding mode, floating point, 5.2.4.2.2 - 6.3.1.7, F.3, F.4 RSIZE_MAX macro, K.3.3, K.3.4, K.3.5.1.2, -real floating types, 6.2.5 K.3.5.3.5, K.3.5.3.6, K.3.5.3.12, K.3.5.3.13, -real type domain, 6.2.5 K.3.5.4.1, K.3.6.2.1, K.3.6.3.1, K.3.6.3.2, -real types, 6.2.5 K.3.6.4.1, K.3.6.5.1, K.3.6.5.2, K.3.7.1.1, -real-floating, 7.12.3 K.3.7.1.2, K.3.7.1.3, K.3.7.1.4, K.3.7.2.1, -realloc function, 7.22.3, 7.22.3.5 K.3.7.2.2, K.3.7.3.1, K.3.7.4.1, K.3.7.4.2, -recommended practice, 3.17 K.3.8.2.1, K.3.8.2.2, K.3.9.1.3, K.3.9.1.4, -recursion, 6.5.2.2 K.3.9.1.8, K.3.9.1.9, K.3.9.2.1.1, K.3.9.2.1.2, -recursive function call, 6.5.2.2 K.3.9.2.1.3, K.3.9.2.1.4, K.3.9.2.2.1, -redefinition of macro, 6.10.3 K.3.9.2.2.2, K.3.9.2.3.1, K.3.9.3.1.1, -reentrancy, 5.1.2.3, 5.2.3 K.3.9.3.2.1, K.3.9.3.2.2 - library functions, 7.1.4 rsize_t type, K.3.3, K.3.4, K.3.5, K.3.5.3.2, -referenced type, 6.2.5 K.3.6, K.3.7, K.3.8, K.3.9, K.3.9.1.2 -register storage-class specifier, 6.7.1, 6.9 runtime-constraint, 3.18 -relational expressions, 6.5.8 Runtime-constraint handling functions, K.3.6.1 -relaxed atomic operations, 5.1.2.4 rvalue, 6.3.2.1 -release fence, 7.17.4 -release operation, 5.1.2.4 same scope, 6.2.1 -release sequence, 5.1.2.4 save calling environment function, 7.13.1 -reliability of data, interrupted, 5.1.2.3 scalar types, 6.2.5 -remainder assignment operator (%=), 6.5.16.2 scalbln function, 7.12.6.13, F.3, F.10.3.13 -remainder functions, 7.12.10, F.10.7 scalbln type-generic macro, 7.24 -remainder functions, 7.12.10.2, 7.12.10.3, F.3, scalbn function, 7.12.6.13, F.3, F.10.3.13 - F.10.7.2 scalbn type-generic macro, 7.24 -remainder operator (%), 6.2.6.2, 6.5.5 scanf function, 7.21.1, 7.21.6.4, 7.21.6.11 -remainder type-generic macro, 7.24 scanf_s function, K.3.5.3.4, K.3.5.3.11 -remove function, 7.21.4.1, 7.21.4.4, K.3.5.1.2 scanlist, 7.21.6.2, 7.28.2.2 -remquo functions, 7.12.10.3, F.3, F.10.7.3 scanset, 7.21.6.2, 7.28.2.2 -remquo type-generic macro, 7.24 SCHAR_MAX macro, 5.2.4.2.1 -rename function, 7.21.4.2 SCHAR_MIN macro, 5.2.4.2.1 -representations of types, 6.2.6 SCNcFASTN macros, 7.8.1 - pointer, 6.2.5 SCNcLEASTN macros, 7.8.1 -rescanning and replacement, 6.10.3.4 SCNcMAX macros, 7.8.1 -reserved identifiers, 6.4.1, 7.1.3, K.3.1.2 SCNcN macros, 7.8.1 -restartable multibyte/wide character conversion SCNcPTR macros, 7.8.1 - functions, 7.27.1, 7.28.6.3, K.3.9.3.1 scope of identifier, 6.2.1, 6.9.2 -restartable multibyte/wide string conversion search functions - functions, 7.28.6.4, K.3.9.3.2 string, 7.23.5, K.3.7.3 -restore calling environment function, 7.13.2 utility, 7.22.5, K.3.6.3 -restrict type qualifier, 6.7.3, 6.7.3.1 wide string, 7.28.4.5, K.3.9.2.3 -restrict-qualified type, 6.2.5, 6.7.3 SEEK_CUR macro, 7.21.1, 7.21.9.2 -return statement, 6.8.6.4, F.6 SEEK_END macro, 7.21.1, 7.21.9.2 - -[page 671] - -SEEK_SET macro, 7.21.1, 7.21.9.2 signal function, 7.14.1.1, 7.22.4.5, 7.22.4.7 -selection statements, 6.8.4 signal handler, 5.1.2.3, 5.2.3, 7.14.1.1, 7.14.2.1 -self-referential structure, 6.7.2.3 signal handling functions, 7.14.1 -semicolon punctuator (;), 6.7, 6.7.2.1, 6.8.3, signal.h header, 7.14, 7.30.6 - 6.8.5, 6.8.6 signaling NaN, 5.2.4.2.2, F.2.1 -separate compilation, 5.1.1.1 signals, 5.1.2.3, 5.2.3, 7.14.1 -separate translation, 5.1.1.1 signbit macro, 7.12.3.6, F.3 -sequence points, 5.1.2.3, 6.5.2.2, 6.5.13, 6.5.14, signed char type, 6.2.5, 7.21.6.1, 7.21.6.2, - 6.5.15, 6.5.17, 6.7.3, 6.7.3.1, 6.7.6, 6.8, 7.28.2.1, 7.28.2.2, K.3.5.3.2, K.3.9.1.2 - 7.1.4, 7.21.6, 7.22.5, 7.28.2, C, K.3.6.3 signed character, 6.3.1.1 -sequenced after, see sequenced before signed integer types, 6.2.5, 6.3.1.3, 6.4.4.1 -sequenced before, 5.1.2.3, 6.5, 6.5.2.2, 6.5.2.4, signed type conversion, 6.3.1.1, 6.3.1.3, 6.3.1.4, - 6.5.16, see also indeterminately sequenced, 6.3.1.8 - unsequenced signed types, 6.2.5, 6.7.2 -sequencing of statements, 6.8 significand part, 6.4.4.2 -set_constraint_handler_s function, SIGSEGV macro, 7.14, 7.14.1.1 - K.3.1.4, K.3.6.1.1, K.3.6.1.2, K.3.6.1.3 SIGTERM macro, 7.14 -setbuf function, 7.21.3, 7.21.5.1, 7.21.5.5 simple assignment operator (=), 6.5.16.1 -setjmp macro, 7.1.3, 7.13.1.1, 7.13.2.1 sin functions, 7.12.4.6, F.10.1.6 -setjmp.h header, 7.13 sin type-generic macro, 7.24, G.7 -setlocale function, 7.11.1.1, 7.11.2.1 single-byte character, 3.7.1, 5.2.1.2 -setvbuf function, 7.21.1, 7.21.3, 7.21.5.1, single-byte/wide character conversion functions, - 7.21.5.5, 7.21.5.6 7.28.6.1 -shall, 4 single-precision arithmetic, 5.1.2.3 -shift expressions, 6.5.7 single-quote escape sequence (\'), 6.4.4.4, 6.4.5 -shift sequence, 7.1.1 singularity, 7.12.1 -shift states, 5.2.1.2 sinh functions, 7.12.5.5, F.10.2.5 -short identifier, character, 5.2.4.1, 6.4.3 sinh type-generic macro, 7.24, G.7 -short int type, 6.2.5, 6.3.1.1, 6.7.2, 7.21.6.1, SIZE_MAX macro, 7.20.3 - 7.21.6.2, 7.28.2.1, 7.28.2.2 size_t type, 6.2.8, 6.5.3.4, 7.19, 7.20.3, 7.21.1, -short int type conversion, 6.3.1.1, 6.3.1.3, 7.21.6.1, 7.21.6.2, 7.22, 7.23.1, 7.26.1, 7.27, - 6.3.1.4, 6.3.1.8 7.28.1, 7.28.2.1, 7.28.2.2, K.3.3, K.3.4, -SHRT_MAX macro, 5.2.4.2.1 K.3.5, K.3.6, K.3.7, K.3.8, K.3.9, K.3.9.1.2 -SHRT_MIN macro, 5.2.4.2.1 sizeof operator, 6.3.2.1, 6.5.3, 6.5.3.4 -side effects, 5.1.2.3, 6.2.6.1, 6.3.2.2, 6.5, 6.5.2.4, snprintf function, 7.21.6.5, 7.21.6.12, - 6.5.16, 6.7.9, 6.8.3, 7.6, 7.6.1, 7.21.7.5, K.3.5.3.5 - 7.21.7.7, 7.28.3.6, 7.28.3.8, F.8.1, F.9.1, snprintf_s function, K.3.5.3.5, K.3.5.3.6 - F.9.3 snwprintf_s function, K.3.9.1.3, K.3.9.1.4 -SIG_ATOMIC_MAX macro, 7.20.3 sorting utility functions, 7.22.5, K.3.6.3 -SIG_ATOMIC_MIN macro, 7.20.3 source character set, 5.1.1.2, 5.2.1 -sig_atomic_t type, 5.1.2.3, 7.14, 7.14.1.1, source file, 5.1.1.1 - 7.20.3 name, 6.10.4, 6.10.8.1 -SIG_DFL macro, 7.14, 7.14.1.1 source file inclusion, 6.10.2 -SIG_ERR macro, 7.14, 7.14.1.1 source lines, 5.1.1.2 -SIG_IGN macro, 7.14, 7.14.1.1 source text, 5.1.1.2 -SIGABRT macro, 7.14, 7.22.4.1 space character (' '), 5.1.1.2, 5.2.1, 6.4, 7.4.1.3, -SIGFPE macro, 7.12.1, 7.14, 7.14.1.1, J.5.17 7.4.1.10, 7.29.2.1.3 -SIGILL macro, 7.14, 7.14.1.1 sprintf function, 7.21.6.6, 7.21.6.13, K.3.5.3.6 -SIGINT macro, 7.14 sprintf_s function, K.3.5.3.5, K.3.5.3.6 -sign and magnitude, 6.2.6.2 sqrt functions, 7.12.7.5, F.3, F.10.4.5 -sign bit, 6.2.6.2 sqrt type-generic macro, 7.24 - -[page 672] - -srand function, 7.22.2.2 expression, 6.8.3 -sscanf function, 7.21.6.7, 7.21.6.14 for, 6.8.5.3 -sscanf_s function, K.3.5.3.7, K.3.5.3.14 goto, 6.8.6.1 -standard error stream, 7.21.1, 7.21.3, 7.21.10.4 if, 6.8.4.1 -standard headers, 4, 7.1.2 iteration, 6.8.5 - , 7.2 jump, 6.8.6 - , 5.2.4.2.2, 6.10.8.3, 7.1.2, 7.3, labeled, 6.8.1 - 7.24, 7.30.1, G.6, J.5.17 null, 6.8.3 - , 7.4, 7.30.2 return, 6.8.6.4, F.6 - , 7.5, 7.30.3, K.3.2 selection, 6.8.4 - , 5.1.2.3, 5.2.4.2.2, 7.6, 7.12, F, H sequencing, 6.8 - , 4, 5.2.4.2.2, 7.7, 7.22.1.3, switch, 6.8.4.2 - 7.28.4.1.1 while, 6.8.5.1 - , 7.8, 7.30.4 static assertions, 6.7.10 - , 4, 7.9 static storage duration, 6.2.4 - , 4, 5.2.4.2.1, 6.2.5, 7.10 static storage-class specifier, 6.2.2, 6.2.4, 6.7.1 - , 7.11, 7.30.5 static, in array declarators, 6.7.6.2, 6.7.6.3 - , 5.2.4.2.2, 6.5, 7.12, 7.24, F, F.10, static_assert declaration, 6.7.10 - J.5.17 static_assert macro, 7.2 - , 7.13 stdalign.h header, 4, 7.15 - , 7.14, 7.30.6 stdarg.h header, 4, 6.7.6.3, 7.16 - , 4, 7.15 stdatomic.h header, 6.10.8.3, 7.1.2, 7.17 - , 4, 6.7.6.3, 7.16 stdbool.h header, 4, 7.18, 7.30.7, H - , 6.10.8.3, 7.1.2, 7.17 STDC, 6.10.6, 6.11.8 - , 4, 7.18, 7.30.7, H stddef.h header, 4, 6.3.2.1, 6.3.2.3, 6.4.4.4, - , 4, 6.3.2.1, 6.3.2.3, 6.4.4.4, 6.4.5, 6.5.3.4, 6.5.6, 7.19, K.3.3 - 6.4.5, 6.5.3.4, 6.5.6, 7.19, K.3.3 stderr macro, 7.21.1, 7.21.2, 7.21.3 - , 4, 5.2.4.2, 6.10.1, 7.8, 7.20, stdin macro, 7.21.1, 7.21.2, 7.21.3, 7.21.6.4, - 7.30.8, K.3.3, K.3.4 7.21.7.6, 7.28.2.12, 7.28.3.7, K.3.5.3.4, - , 5.2.4.2.2, 7.21, 7.30.9, F, K.3.5 K.3.5.4.1, K.3.9.1.14 - , 5.2.4.2.2, 7.22, 7.30.10, F, stdint.h header, 4, 5.2.4.2, 6.10.1, 7.8, 7.20, - K.3.1.4, K.3.6 7.30.8, K.3.3, K.3.4 - , 7.23, 7.30.11, K.3.7 stdio.h header, 5.2.4.2.2, 7.21, 7.30.9, F, K.3.5 - , 7.24, G.7 stdlib.h header, 5.2.4.2.2, 7.22, 7.30.10, F, - , 6.10.8.3, 7.1.2, 7.25 K.3.1.4, K.3.6 - , 7.26, K.3.8 stdout macro, 7.21.1, 7.21.2, 7.21.3, 7.21.6.3, - , 6.4.4.4, 6.4.5, 7.27 7.21.7.8, 7.21.7.9, 7.28.2.11, 7.28.3.9 - , 5.2.4.2.2, 7.21.1, 7.28, 7.30.12, storage duration, 6.2.4 - F, K.3.9 storage order of array, 6.5.2.1 - , 7.29, 7.30.13 storage unit (bit-field), 6.2.6.1, 6.7.2.1 -standard input stream, 7.21.1, 7.21.3 storage-class specifiers, 6.7.1, 6.11.5 -standard integer types, 6.2.5 strcat function, 7.23.3.1 -standard output stream, 7.21.1, 7.21.3 strcat_s function, K.3.7.2.1 -standard signed integer types, 6.2.5 strchr function, 7.23.5.2 -state-dependent encoding, 5.2.1.2, 7.22.7, K.3.6.4 strcmp function, 7.23.4, 7.23.4.2 -statements, 6.8 strcoll function, 7.11.1.1, 7.23.4.3, 7.23.4.5 - break, 6.8.6.3 strcpy function, 7.23.2.3 - compound, 6.8.2 strcpy_s function, K.3.7.1.3 - continue, 6.8.6.2 strcspn function, 7.23.5.3 - do, 6.8.5.2 streams, 7.21.2, 7.22.4.4 - else, 6.8.4.1 fully buffered, 7.21.3 - -[page 673] - - line buffered, 7.21.3 strtoumax function, 7.8.2.3 - orientation, 7.21.2 struct hack, see flexible array member - standard error, 7.21.1, 7.21.3 struct lconv, 7.11 - standard input, 7.21.1, 7.21.3 struct tm, 7.26.1 - standard output, 7.21.1, 7.21.3 structure - unbuffered, 7.21.3 arrow operator (->), 6.5.2.3 -strerror function, 7.21.10.4, 7.23.6.2 content, 6.7.2.3 -strerror_s function, K.3.7.4.2, K.3.7.4.3 dot operator (.), 6.5.2.3 -strerrorlen_s function, K.3.7.4.3 initialization, 6.7.9 -strftime function, 7.11.1.1, 7.26.3, 7.26.3.5, member alignment, 6.7.2.1 - 7.28.5.1, K.3.8.2, K.3.8.2.1, K.3.8.2.2 member name space, 6.2.3 -stricter, 6.2.8 member operator (.), 6.3.2.1, 6.5.2.3 -strictly conforming program, 4 pointer operator (->), 6.5.2.3 -string, 7.1.1 specifier, 6.7.2.1 - comparison functions, 7.23.4 tag, 6.2.3, 6.7.2.3 - concatenation functions, 7.23.3, K.3.7.2 type, 6.2.5, 6.7.2.1 - conversion functions, 7.11.1.1 strxfrm function, 7.11.1.1, 7.23.4.5 - copying functions, 7.23.2, K.3.7.1 subnormal floating-point numbers, 5.2.4.2.2 - library function conventions, 7.23.1 subscripting, 6.5.2.1 - literal, 5.1.1.2, 5.2.1, 6.3.2.1, 6.4.5, 6.5.1, 6.7.9 subtraction assignment operator (-=), 6.5.16.2 - miscellaneous functions, 7.23.6, K.3.7.4 subtraction operator (-), 6.2.6.2, 6.5.6, F.3, G.5.2 - numeric conversion functions, 7.8.2.3, 7.22.1 suffix - search functions, 7.23.5, K.3.7.3 floating constant, 6.4.4.2 -string handling header, 7.23, K.3.7 integer constant, 6.4.4.1 -string.h header, 7.23, 7.30.11, K.3.7 switch body, 6.8.4.2 -stringizing, 6.10.3.2, 6.10.9 switch case label, 6.8.1, 6.8.4.2 -strlen function, 7.23.6.3 switch default label, 6.8.1, 6.8.4.2 -strncat function, 7.23.3.2 switch statement, 6.8.1, 6.8.4.2 -strncat_s function, K.3.7.2.2 swprintf function, 7.28.2.3, 7.28.2.7, -strncmp function, 7.23.4, 7.23.4.4 K.3.9.1.3, K.3.9.1.4 -strncpy function, 7.23.2.4 swprintf_s function, K.3.9.1.3, K.3.9.1.4 -strncpy_s function, K.3.7.1.4 swscanf function, 7.28.2.4, 7.28.2.8 -strnlen_s function, K.3.7.4.4 swscanf_s function, K.3.9.1.5, K.3.9.1.10 -stronger, 6.2.8 symbols, 3 -strpbrk function, 7.23.5.4 synchronization operation, 5.1.2.4 -strrchr function, 7.23.5.5 synchronize with, 5.1.2.4 -strspn function, 7.23.5.6 syntactic categories, 6.1 -strstr function, 7.23.5.7 syntax notation, 6.1 -strtod function, 7.12.11.2, 7.21.6.2, 7.22.1.3, syntax rule precedence, 5.1.1.2 - 7.28.2.2, F.3 syntax summary, language, A -strtof function, 7.12.11.2, 7.22.1.3, F.3 system function, 7.22.4.8 -strtoimax function, 7.8.2.3 -strtok function, 7.23.5.8 tab characters, 5.2.1, 6.4 -strtok_s function, K.3.7.3.1 tag compatibility, 6.2.7 -strtol function, 7.8.2.3, 7.21.6.2, 7.22.1.2, tag name space, 6.2.3 - 7.22.1.4, 7.28.2.2 tags, 6.7.2.3 -strtold function, 7.12.11.2, 7.22.1.3, F.3 tan functions, 7.12.4.7, F.10.1.7 -strtoll function, 7.8.2.3, 7.22.1.2, 7.22.1.4 tan type-generic macro, 7.24, G.7 -strtoul function, 7.8.2.3, 7.21.6.2, 7.22.1.2, tanh functions, 7.12.5.6, F.10.2.6 - 7.22.1.4, 7.28.2.2 tanh type-generic macro, 7.24, G.7 -strtoull function, 7.8.2.3, 7.22.1.2, 7.22.1.4 temporary lifetime, 6.2.4 - -[page 674] - -tentative definition, 6.9.2 towlower function, 7.29.3.1.1, 7.29.3.2.1 -terms, 3 towupper function, 7.29.3.1.2, 7.29.3.2.1 -text streams, 7.21.2, 7.21.7.10, 7.21.9.2, 7.21.9.4 translation environment, 5, 5.1.1 -tgamma functions, 7.12.8.4, F.10.5.4 translation limits, 5.2.4.1 -tgamma type-generic macro, 7.24 translation phases, 5.1.1.2 -tgmath.h header, 7.24, G.7 translation unit, 5.1.1.1, 6.9 -thrd_create function, 7.25.1, 7.25.5.1 trap, see perform a trap -thrd_current function, 7.25.5.2 trap representation, 3.19.4, 6.2.6.1, 6.2.6.2, -thrd_detach function, 7.25.5.3, 7.25.5.6 6.3.2.3, 6.5.2.3 -thrd_equal function, 7.25.5.4 trigonometric functions -thrd_exit function, 7.25.5.5 complex, 7.3.5, G.6.1 -thrd_join function, 7.25.5.3, 7.25.5.6 real, 7.12.4, F.10.1 -thrd_sleep function, 7.25.5.7 trigraph sequences, 5.1.1.2, 5.2.1.1 -thrd_start_t type, 7.25.1 true macro, 7.18 -thrd_t type, 7.25.1 trunc functions, 7.12.9.8, F.10.6.8 -thrd_yield function, 7.25.5.8 trunc type-generic macro, 7.24 -thread of execution, 5.1.2.4, 7.1.4, 7.6, 7.22.4.6 truncation, 6.3.1.4, 7.12.9.8, 7.21.3, 7.21.5.3 -thread storage duration, 6.2.4, 7.6 truncation toward zero, 6.5.5 -threads header, 7.25 tss_create function, 7.25.6.1 -threads.h header, 6.10.8.3, 7.1.2, 7.25 tss_delete function, 7.25.6.2 -time TSS_DTOR_ITERATIONS macro, 7.25.1 - broken down, 7.26.1, 7.26.2.3, 7.26.3, 7.26.3.1, tss_dtor_t type, 7.25.1 - 7.26.3.3, 7.26.3.4, 7.26.3.5, K.3.8.2.1, tss_get function, 7.25.6.3 - K.3.8.2.3, K.3.8.2.4 tss_set function, 7.25.6.4 - calendar, 7.26.1, 7.26.2.2, 7.26.2.3, 7.26.2.4, tss_t type, 7.25.1 - 7.26.3.2, 7.26.3.3, 7.26.3.4, K.3.8.2.2, two's complement, 6.2.6.2, 7.20.1.1 - K.3.8.2.3, K.3.8.2.4 type category, 6.2.5 - components, 7.26.1, K.3.8.1 type conversion, 6.3 - conversion functions, 7.26.3, K.3.8.2 type definitions, 6.7.8 - wide character, 7.28.5 type domain, 6.2.5, G.2 - local, 7.26.1 type names, 6.7.7 - manipulation functions, 7.26.2 type punning, 6.5.2.3 - normalized broken down, K.3.8.1, K.3.8.2.1 type qualifiers, 6.7.3 -time function, 7.26.2.4 type specifiers, 6.7.2 -time.h header, 7.26, K.3.8 type-generic macro, 7.24, G.7 -time_t type, 7.26.1 typedef declaration, 6.7.8 -TIME_UTC macro, 7.25.7.1 typedef storage-class specifier, 6.7.1, 6.7.8 -tm structure type, 7.26.1, 7.28.1, K.3.8.1 types, 6.2.5 -TMP_MAX macro, 7.21.1, 7.21.4.3, 7.21.4.4 _Atomic qualified, 6.2.5, 6.2.6.1, 6.5.2.3, -TMP_MAX_S macro, K.3.5, K.3.5.1.1, K.3.5.1.2 6.5.2.4, 6.5.16.2, 6.7.2, 6.7.3 -tmpfile function, 7.21.4.3, 7.22.4.4 atomic, 5.1.2.3, 6.10.8.3, 7.17.6 -tmpfile_s function, K.3.5.1.1, K.3.5.1.2 character, 6.7.9 -tmpnam function, 7.21.1, 7.21.4.3, 7.21.4.4, compatible, 6.2.7, 6.7.2, 6.7.3, 6.7.6 - K.3.5.1.2 complex, 6.2.5, G -tmpnam_s function, K.3.5, K.3.5.1.1, K.3.5.1.2 composite, 6.2.7 -token, 5.1.1.2, 6.4, see also preprocessing tokens const qualified, 6.7.3 -token concatenation, 6.10.3.3 conversions, 6.3 -token pasting, 6.10.3.3 imaginary, G -tolower function, 7.4.2.1 restrict qualified, 6.7.3 -toupper function, 7.4.2.2 volatile qualified, 6.7.3 -towctrans function, 7.29.3.2.1, 7.29.3.2.2 - -[page 675] - -uchar.h header, 6.4.4.4, 6.4.5, 7.27 universal character name, 6.4.3 -UCHAR_MAX macro, 5.2.4.2.1 unnormalized floating-point numbers, 5.2.4.2.2 -UINT_FASTN_MAX macros, 7.20.2.3 unqualified type, 6.2.5 -uint_fastN_t types, 7.20.1.3 unqualified version of type, 6.2.5 -uint_least16_t type, 7.27 unsequenced, 5.1.2.3, 6.5, 6.5.16, see also -uint_least32_t type, 7.27 indeterminately sequenced, sequenced -UINT_LEASTN_MAX macros, 7.20.2.2 before -uint_leastN_t types, 7.20.1.2 unsigned char type, K.3.5.3.2, K.3.9.1.2 -UINT_MAX macro, 5.2.4.2.1 unsigned integer suffix, u or U, 6.4.4.1 -UINTMAX_C macro, 7.20.4.2 unsigned integer types, 6.2.5, 6.3.1.3, 6.4.4.1 -UINTMAX_MAX macro, 7.8.2.3, 7.8.2.4, 7.20.2.5 unsigned type conversion, 6.3.1.1, 6.3.1.3, -uintmax_t type, 7.20.1.5, 7.21.6.1, 7.21.6.2, 6.3.1.4, 6.3.1.8 - 7.28.2.1, 7.28.2.2 unsigned types, 6.2.5, 6.7.2, 7.21.6.1, 7.21.6.2, -UINTN_C macros, 7.20.4.1 7.28.2.1, 7.28.2.2 -UINTN_MAX macros, 7.20.2.1 unspecified behavior, 3.4.4, 4, J.1 -uintN_t types, 7.20.1.1 unspecified value, 3.19.3 -UINTPTR_MAX macro, 7.20.2.4 uppercase letter, 5.2.1 -uintptr_t type, 7.20.1.4 use of library functions, 7.1.4 -ULLONG_MAX macro, 5.2.4.2.1, 7.22.1.4, USHRT_MAX macro, 5.2.4.2.1 - 7.28.4.1.2 usual arithmetic conversions, 6.3.1.8, 6.5.5, 6.5.6, -ULONG_MAX macro, 5.2.4.2.1, 7.22.1.4, 6.5.8, 6.5.9, 6.5.10, 6.5.11, 6.5.12, 6.5.15 - 7.28.4.1.2 UTF-16, 6.10.8.2 -unary arithmetic operators, 6.5.3.3 UTF-32, 6.10.8.2 -unary expression, 6.5.3 UTF-8 string literal, see string literal -unary minus operator (-), 6.5.3.3, F.3 utilities, general, 7.22, K.3.6 -unary operators, 6.5.3 wide string, 7.28.4, K.3.9.2 -unary plus operator (+), 6.5.3.3 -unbuffered stream, 7.21.3 va_arg macro, 7.16, 7.16.1, 7.16.1.1, 7.16.1.2, -undef preprocessing directive, 6.10.3.5, 7.1.3, 7.16.1.4, 7.21.6.8, 7.21.6.9, 7.21.6.10, - 7.1.4 7.21.6.11, 7.21.6.12, 7.21.6.13, 7.21.6.14, -undefined behavior, 3.4.3, 4, J.2 7.28.2.5, 7.28.2.6, 7.28.2.7, 7.28.2.8, -underscore character, 6.4.2.1 7.28.2.9, 7.28.2.10, K.3.5.3.9, K.3.5.3.11, -underscore, leading, in identifier, 7.1.3 K.3.5.3.14, K.3.9.1.7, K.3.9.1.10, K.3.9.1.12 -ungetc function, 7.21.1, 7.21.7.10, 7.21.9.2, va_copy macro, 7.1.3, 7.16, 7.16.1, 7.16.1.1, - 7.21.9.3 7.16.1.2, 7.16.1.3 -ungetwc function, 7.21.1, 7.28.3.10 va_end macro, 7.1.3, 7.16, 7.16.1, 7.16.1.3, -Unicode, 7.27, see also char16_t type, 7.16.1.4, 7.21.6.8, 7.21.6.9, 7.21.6.10, - char32_t type, wchar_t type 7.21.6.11, 7.21.6.12, 7.21.6.13, 7.21.6.14, -Unicode required set, 6.10.8.2 7.28.2.5, 7.28.2.6, 7.28.2.7, 7.28.2.8, -union 7.28.2.9, 7.28.2.10, K.3.5.3.9, K.3.5.3.11, - arrow operator (->), 6.5.2.3 K.3.5.3.14, K.3.9.1.7, K.3.9.1.10, K.3.9.1.12 - content, 6.7.2.3 va_list type, 7.16, 7.16.1.3 - dot operator (.), 6.5.2.3 va_start macro, 7.16, 7.16.1, 7.16.1.1, - initialization, 6.7.9 7.16.1.2, 7.16.1.3, 7.16.1.4, 7.21.6.8, - member alignment, 6.7.2.1 7.21.6.9, 7.21.6.10, 7.21.6.11, 7.21.6.12, - member name space, 6.2.3 7.21.6.13, 7.21.6.14, 7.28.2.5, 7.28.2.6, - member operator (.), 6.3.2.1, 6.5.2.3 7.28.2.7, 7.28.2.8, 7.28.2.9, 7.28.2.10, - pointer operator (->), 6.5.2.3 K.3.5.3.9, K.3.5.3.11, K.3.5.3.14, K.3.9.1.7, - specifier, 6.7.2.1 K.3.9.1.10, K.3.9.1.12 - tag, 6.2.3, 6.7.2.3 value, 3.19 - type, 6.2.5, 6.7.2.1 value bits, 6.2.6.2 - -[page 676] - -variable arguments, 6.10.3, 7.16 vswscanf function, 7.28.2.8 -variable arguments header, 7.16 vswscanf_s function, K.3.9.1.10 -variable length array, 6.7.6, 6.7.6.2, 6.10.8.3 vwprintf function, 7.21.1, 7.28.2.9, K.3.9.1.11 -variably modified type, 6.7.6, 6.7.6.2, 6.10.8.3 vwprintf_s function, K.3.9.1.11 -vertical-tab character, 5.2.1, 6.4 vwscanf function, 7.21.1, 7.28.2.10, 7.28.3.10 -vertical-tab escape sequence (\v), 5.2.2, 6.4.4.4, vwscanf_s function, K.3.9.1.12 - 7.4.1.10 -vfprintf function, 7.21.1, 7.21.6.8, K.3.5.3.8 warnings, I -vfprintf_s function, K.3.5.3.8, K.3.5.3.9, wchar.h header, 5.2.4.2.2, 7.21.1, 7.28, 7.30.12, - K.3.5.3.11, K.3.5.3.14 F, K.3.9 -vfscanf function, 7.21.1, 7.21.6.8, 7.21.6.9 WCHAR_MAX macro, 7.20.3, 7.28.1 -vfscanf_s function, K.3.5.3.9, K.3.5.3.11, WCHAR_MIN macro, 7.20.3, 7.28.1 - K.3.5.3.14 wchar_t type, 3.7.3, 6.4.5, 6.7.9, 6.10.8.2, 7.19, -vfwprintf function, 7.21.1, 7.28.2.5, K.3.9.1.6 7.20.3, 7.21.6.1, 7.21.6.2, 7.22, 7.28.1, -vfwprintf_s function, K.3.9.1.6 7.28.2.1, 7.28.2.2 -vfwscanf function, 7.21.1, 7.28.2.6, 7.28.3.10 wcrtomb function, 7.21.3, 7.21.6.2, 7.28.2.2, -vfwscanf_s function, K.3.9.1.7 7.28.6.3.3, 7.28.6.4.2, K.3.6.5.2, K.3.9.3.1, -visibility of identifier, 6.2.1 K.3.9.3.2.2 -visible sequence of side effects, 5.1.2.4 wcrtomb_s function, K.3.9.3.1, K.3.9.3.1.1 -visible side effect, 5.1.2.4 wcscat function, 7.28.4.3.1 -VLA, see variable length array wcscat_s function, K.3.9.2.2.1 -void expression, 6.3.2.2 wcschr function, 7.28.4.5.1 -void function parameter, 6.7.6.3 wcscmp function, 7.28.4.4.1, 7.28.4.4.4 -void type, 6.2.5, 6.3.2.2, 6.7.2, K.3.5.3.2, wcscoll function, 7.28.4.4.2, 7.28.4.4.4 - K.3.9.1.2 wcscpy function, 7.28.4.2.1 -void type conversion, 6.3.2.2 wcscpy_s function, K.3.9.2.1.1 -volatile storage, 5.1.2.3 wcscspn function, 7.28.4.5.2 -volatile type qualifier, 6.7.3 wcsftime function, 7.11.1.1, 7.28.5.1 -volatile-qualified type, 6.2.5, 6.7.3 wcslen function, 7.28.4.6.1 -vprintf function, 7.21.1, 7.21.6.8, 7.21.6.10, wcsncat function, 7.28.4.3.2 - K.3.5.3.10 wcsncat_s function, K.3.9.2.2.2 -vprintf_s function, K.3.5.3.9, K.3.5.3.10, wcsncmp function, 7.28.4.4.3 - K.3.5.3.11, K.3.5.3.14 wcsncpy function, 7.28.4.2.2 -vscanf function, 7.21.1, 7.21.6.8, 7.21.6.11 wcsncpy_s function, K.3.9.2.1.2 -vscanf_s function, K.3.5.3.9, K.3.5.3.11, wcsnlen_s function, K.3.9.2.4.1 - K.3.5.3.14 wcspbrk function, 7.28.4.5.3 -vsnprintf function, 7.21.6.8, 7.21.6.12, wcsrchr function, 7.28.4.5.4 - K.3.5.3.12 wcsrtombs function, 7.28.6.4.2, K.3.9.3.2 -vsnprintf_s function, K.3.5.3.9, K.3.5.3.11, wcsrtombs_s function, K.3.9.3.2, K.3.9.3.2.2 - K.3.5.3.12, K.3.5.3.13, K.3.5.3.14 wcsspn function, 7.28.4.5.5 -vsnwprintf_s function, K.3.9.1.8, K.3.9.1.9 wcsstr function, 7.28.4.5.6 -vsprintf function, 7.21.6.8, 7.21.6.13, wcstod function, 7.21.6.2, 7.28.2.2 - K.3.5.3.13 wcstod function, 7.28.4.1.1 -vsprintf_s function, K.3.5.3.9, K.3.5.3.11, wcstof function, 7.28.4.1.1 - K.3.5.3.12, K.3.5.3.13, K.3.5.3.14 wcstoimax function, 7.8.2.4 -vsscanf function, 7.21.6.8, 7.21.6.14 wcstok function, 7.28.4.5.7 -vsscanf_s function, K.3.5.3.9, K.3.5.3.11, wcstok_s function, K.3.9.2.3.1 - K.3.5.3.14 wcstol function, 7.8.2.4, 7.21.6.2, 7.28.2.2, -vswprintf function, 7.28.2.7, K.3.9.1.8, 7.28.4.1.2 - K.3.9.1.9 wcstold function, 7.28.4.1.1 -vswprintf_s function, K.3.9.1.8, K.3.9.1.9 wcstoll function, 7.8.2.4, 7.28.4.1.2 - -[page 677] - -wcstombs function, 7.22.8.2, 7.28.6.4 7.29.1 -wcstombs_s function, K.3.6.5.2 wmemchr function, 7.28.4.5.8 -wcstoul function, 7.8.2.4, 7.21.6.2, 7.28.2.2, wmemcmp function, 7.28.4.4.5 - 7.28.4.1.2 wmemcpy function, 7.28.4.2.3 -wcstoull function, 7.8.2.4, 7.28.4.1.2 wmemcpy_s function, K.3.9.2.1.3 -wcstoumax function, 7.8.2.4 wmemmove function, 7.28.4.2.4 -wcsxfrm function, 7.28.4.4.4 wmemmove_s function, K.3.9.2.1.4 -wctob function, 7.28.6.1.2, 7.29.2.1 wmemset function, 7.28.4.6.2 -wctomb function, 7.22.7.3, 7.22.8.2, 7.28.6.3 wprintf function, 7.21.1, 7.28.2.9, 7.28.2.11, -wctomb_s function, K.3.6.4.1 K.3.9.1.13 -wctrans function, 7.29.3.2.1, 7.29.3.2.2 wprintf_s function, K.3.9.1.13 -wctrans_t type, 7.29.1, 7.29.3.2.2 wscanf function, 7.21.1, 7.28.2.10, 7.28.2.12, -wctype function, 7.29.2.2.1, 7.29.2.2.2 7.28.3.10 -wctype.h header, 7.29, 7.30.13 wscanf_s function, K.3.9.1.12, K.3.9.1.14 -wctype_t type, 7.29.1, 7.29.2.2.2 -weaker, 6.2.8 xor macro, 7.9 -WEOF macro, 7.28.1, 7.28.3.1, 7.28.3.3, 7.28.3.6, xor_eq macro, 7.9 - 7.28.3.7, 7.28.3.8, 7.28.3.9, 7.28.3.10, xtime type, 7.25.1, 7.25.3.5, 7.25.4.4, 7.25.5.7, - 7.28.6.1.1, 7.29.1 7.25.7.1 -while statement, 6.8.5.1 xtime_get function, 7.25.7.1 -white space, 5.1.1.2, 6.4, 6.10, 7.4.1.10, - 7.29.2.1.10 -white-space characters, 6.4 -wide character, 3.7.3 - case mapping functions, 7.29.3.1 - extensible, 7.29.3.2 - classification functions, 7.29.2.1 - extensible, 7.29.2.2 - constant, 6.4.4.4 - formatted input/output functions, 7.28.2, - K.3.9.1 - input functions, 7.21.1 - input/output functions, 7.21.1, 7.28.3 - output functions, 7.21.1 - single-byte conversion functions, 7.28.6.1 -wide string, 7.1.1 -wide string comparison functions, 7.28.4.4 -wide string concatenation functions, 7.28.4.3, - K.3.9.2.2 -wide string copying functions, 7.28.4.2, K.3.9.2.1 -wide string literal, see string literal -wide string miscellaneous functions, 7.28.4.6, - K.3.9.2.4 -wide string numeric conversion functions, 7.8.2.4, - 7.28.4.1 -wide string search functions, 7.28.4.5, K.3.9.2.3 -wide-oriented stream, 7.21.2 -width, 6.2.6.2 -WINT_MAX macro, 7.20.3 -WINT_MIN macro, 7.20.3 -wint_t type, 7.20.3, 7.21.6.1, 7.28.1, 7.28.2.1, - -[page 678] -- 2.20.1