++ WG14/N1256 Committee Draft -- Septermber 7, 2007 ISO/IEC 9899:TC3-Contents
+Contents
ISO (the International Organization for Standardization) and IEC (the International
Electrotechnical Commission) form the specialized system for worldwide
@@ -476,7 +477,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
also for information only.
-Introduction
+
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
@@ -515,7 +516,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-1. Scope
+
This International Standard specifies the form and establishes the interpretation of
programs written in the C programming language.1) It specifies
@@ -552,7 +553,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
data-processing systems. It is intended for use by implementors and programmers.
-2. Normative references
+
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this International Standard. For dated references,
@@ -584,7 +585,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
designated IEC 559:1989).
-3. Terms, definitions, and symbols
+
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.
@@ -593,9 +594,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
- access
+ access
<execution-time action> to read or modify the value of an object
NOTE 1 Where only one of these two actions is meant, ''read'' or ''modify'' is used.
@@ -607,38 +608,38 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NOTE 3 Expressions that are not evaluated do not access objects.
-3.2
+
- alignment
+ 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
+
- argument
- actual argument
- actual parameter (deprecated)
+ 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
+
- behavior
+ behavior
external appearance or action
-3.4.1
+
- implementation-defined behavior
+ implementation-defined behavior
unspecified behavior where each implementation documents how the choice is made
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
+
- locale-specific behavior
+ locale-specific behavior
behavior that depends on local conventions of nationality, culture, and language that each
implementation documents
@@ -647,9 +648,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters other than the 26 lowercase Latin letters.
-3.4.3
+
- undefined behavior
+ undefined behavior
behavior, upon use of a nonportable or erroneous program construct or of erroneous data,
for which this International Standard imposes no requirements
@@ -662,9 +663,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE An example of undefined behavior is the behavior on integer overflow.
-3.4.4
+
- unspecified behavior
+ 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
@@ -673,18 +674,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
evaluated.
-3.5
+
- bit
+ bit
unit of data storage in the execution environment large enough to hold an object that may
have one of two values
NOTE It need not be possible to express the address of each individual bit of an object.
-3.6
+
- byte
+ byte
addressable unit of data storage large enough to hold any member of the basic character
set of the execution environment
@@ -696,73 +697,73 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
bit.
-3.7
+
- character
+ character
<abstract> member of a set of elements used for the organization, control, or
representation of data
-3.7.1
+
- character
+ character
single-byte character
<C> bit representation that fits in a byte
-3.7.2
+
- multibyte character
+ multibyte character
sequence of one or more bytes representing a member of the extended character set of
either the source or the execution environment
NOTE The extended character set is a superset of the basic character set.
-3.7.3
+
- wide character
+ wide character
bit representation that fits in an object of type wchar_t, capable of representing any
character in the current locale
-3.8
+
- constraint
+ constraint
restriction, either syntactic or semantic, by which the exposition of language elements is
to be interpreted
-3.9
+
- correctly rounded result
+ 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
+
- diagnostic message
+ diagnostic message
message belonging to an implementation-defined subset of the implementation's message
output
-3.11
+
- forward reference
+ forward reference
reference to a later subclause of this International Standard that contains additional
information relevant to this subclause
-3.12
+
- implementation
+ 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
+
- implementation limit
+ implementation limit
restriction imposed upon programs by the implementation
-3.14
+
- object
+ object
region of data storage in the execution environment, the contents of which can represent
values
@@ -770,62 +771,62 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NOTE When referenced, an object may be interpreted as having a particular type; see 6.3.2.1.
-3.15
+
- parameter
+ 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
-3.16
+
- recommended practice
+ 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
-3.17
+
- value
+ value
precise meaning of the contents of an object when interpreted as having a specific type
-3.17.1
+
- implementation-defined value
+ implementation-defined value
unspecified value where each implementation documents how the choice is made
-3.17.2
+
- indeterminate value
+ indeterminate value
either an unspecified value or a trap representation
-3.17.3
+
- unspecified value
+ unspecified value
valid value of the relevant type where this International Standard imposes no
requirements on which value is chosen in any instance
NOTE An unspecified value cannot be a trap representation.
-3.18
+
- ??? x???
+ [^ x ^]
ceiling of x: the least integer greater than or equal to x
- EXAMPLE ???2.4??? is 3, ???-2.4??? is -2.
+ EXAMPLE [^2.4^] is 3, [^-2.4^] is -2.
-3.19
+
- ??? x???
+ [_ x _]
floor of x: the greatest integer less than or equal to x
- EXAMPLE ???2.4??? is 2, ???-2.4??? is -3.
+ EXAMPLE [_2.4_] is 2, [_-2.4_] is -3.
-4. Conformance
+
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 @@ -887,7 +888,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 /* ... */ fesetround(FE_UPWARD); /* ... */ - #endif + #endif +
3) This implies that a conforming implementation reserves no identifiers other than those explicitly
@@ -898,7 +900,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
implementation.
-5. Environment
+
An implementation translates C source files and executes C programs in two data- processing-system environments, which will be called the translation environment and @@ -908,11 +910,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: In this clause, only a few of many possible forward references
have been noted.
-5.1 Conceptual models
+
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 @@ -927,7 +929,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: linkages of identifiers (6.2.2), external definitions (6.9),
preprocessing directives (6.10).
-5.1.1.2 Translation phases
+
The precedence among the syntax rules of translation is specified by the following
phases.5)
@@ -992,7 +994,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character.
-5.1.1.3 Diagnostics
+
A conforming implementation shall produce at least one diagnostic message (identified in an implementation-defined manner) if a preprocessing translation unit or translation unit @@ -1003,7 +1005,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE An implementation shall issue a diagnostic for the translation unit:
char i;
- int 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.
@@ -1014,7 +1017,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
valid program is still correctly translated. It may also successfully translate an invalid program.
-Two execution environments are defined: freestanding and hosted. In both cases, program startup occurs when a designated C function is called by the execution @@ -1024,7 +1027,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 environment.
Forward references: storage durations of objects (6.2.4), initialization (6.7.8).
-5.1.2.1 Freestanding environment
+
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
@@ -1034,7 +1037,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The effect of program termination in a freestanding environment is implementation-
defined.
-5.1.2.2 Hosted environment
+
A hosted environment need not be provided, but shall conform to the following
specifications if present.
@@ -1044,17 +1047,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-5.1.2.2.1 Program startup
+
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) { /* ... */ }
+ 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[]) { /* ... */ }
+ int main(int argc, char *argv[]) { /* ... */ }
+
or equivalent;9) or in some other implementation-defined manner.
If they are declared, the parameters to the main function shall obey the following
@@ -1084,7 +1089,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
char ** argv, and so on.
-5.1.2.2.2 Program execution
+
In a hosted environment, a program may use all the functions, macros, type definitions,
and objects described in the library clause (clause 7).
@@ -1093,7 +1098,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-5.1.2.2.3 Program termination
+
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
@@ -1107,7 +1112,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
will have ended in the former case, even where they would not have in the latter.
-5.1.2.3 Program execution
+
The semantic descriptions in this International Standard describe the behavior of an abstract machine in which issues of optimization are irrelevant. @@ -1171,7 +1176,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
char c1, c2;
/* ... */
- c1 = 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
@@ -1183,7 +1189,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
float f1, f2;
double d;
/* ... */
- f1 = f2 * 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).
@@ -1198,7 +1205,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
double d1, d2;
float f;
d1 = f = expression;
- d2 = (float) expression;
+ d2 = (float) expression;
+
the values assigned to d1 and d2 are required to have been converted to float.
@@ -1214,30 +1222,36 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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; + y = x / 5.0; // not equivalent to y = x * 0.2; +
EXAMPLE 6 To illustrate the grouping behavior of expressions, in the following fragment
int a, b;
/* ... */
- a = a + 32760 + b + 5;
+ a = a + 32760 + b + 5;
+
the expression statement behaves exactly the same as
- a = (((a + 32760) + b) + 5);+ 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);+ 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
- a = ((a + 32765) + b);+ a = ((a + 32765) + b); + or
- a = (a + (b + 32765));+ 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 @@ -1251,10 +1265,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 int sum; char *p; /* ... */ - sum = sum * 10 - '0' + (*p++ = getchar()); + sum = sum * 10 - '0' + (*p++ = getchar()); + the expression statement is grouped as if it were written as
- sum = (((sum * 10) - '0') + ((*(p++)) = (getchar())));+ 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. @@ -1272,9 +1288,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 effects matter, freeing the implementations in other cases. -
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 @@ -1294,18 +1310,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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
+ 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
+ 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+ 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
@@ -1326,7 +1346,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
Before any other processing takes place, each occurrence of one of the following sequences of three characters (called trigraph sequences12)) is replaced with the @@ -1334,24 +1354,29 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
??= # ??) ] ??! |
??( [ ??' ^ ??> }
- ??/ \ ??< { ??- ~
+ ??/ \ ??< { ??- ~
+
No other trigraph sequences exist. Each ? that does not begin one of the trigraphs listed
above is not changed.
EXAMPLE 1
- ??=define arraycheck(a, b) a??(b??) ??!??! b??(a??)+ ??=define arraycheck(a, b) a??(b??) ??!??! b??(a??) + becomes
- #define arraycheck(a, b) a[b] || b[a]+ #define arraycheck(a, b) a[b] || b[a] +
EXAMPLE 2 The following source line
- printf("Eh???/n");
+ printf("Eh???/n");
+
becomes (after replacement of the trigraph sequence ??/)
- printf("Eh?\n");
+ printf("Eh?\n");
+
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
@@ -1390,7 +1415,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
of a sequence of valid multibyte characters.
-5.2.2 Character display semantics
+
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 @@ -1402,33 +1427,31 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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 -
+
- 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 -
+ device is unspecified. +
-
tabulation position. If the active position is at or past the last defined vertical
- tabulation position, the behavior of the display device is unspecified.
+ tabulation position, the behavior of the display device is unspecified.
+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 (7.19.7.3).
-5.2.3 Signals and interrupts
+
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,
@@ -1437,14 +1460,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
image (the instructions that compose the executable representation of a function) on a
per-invocation basis.
-5.2.4 Environmental limits
+
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
+
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:13) @@ -1490,14 +1513,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
14) See ''future language directions'' (6.11.3).
-5.2.4.2 Numerical limits
+
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> (7.18).
-5.2.4.2.1 Sizes of integer types
+
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 @@ -1510,58 +1533,96 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 (absolute value) to those shown, with the same sign.
CHAR_BIT 8 +
+ SCHAR_MIN -127 // -(27 - 1) +
+ SCHAR_MAX +127 // 27 - 1 +
+ UCHAR_MAX 255 // 28 - 1 +
CHAR_MIN see below +
CHAR_MAX see below +
MB_LEN_MAX 1 +
+ SHRT_MIN -32767 // -(215 - 1) +
+ SHRT_MAX +32767 // 215 - 1 +
+ USHRT_MAX 65535 // 216 - 1 +
+ INT_MIN -32767 // -(215 - 1) +
+ INT_MAX +32767 // 215 - 1 +
+ UINT_MAX 65535 // 216 - 1 +
+ LONG_MIN -2147483647 // -(231 - 1) +
+ LONG_MAX +2147483647 // 231 - 1 +
+ ULONG_MAX 4294967295 // 232 - 1 +
+ LLONG_MIN -9223372036854775807 // -(263 - 1) +
+ LLONG_MAX +9223372036854775807 // 263 - 1 +
+ ULLONG_MAX 18446744073709551615 // 264 - 1 +
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.15) The value UCHAR_MAX shall equal 2CHAR_BIT - 1. + UCHAR_MAX.15) The value UCHAR_MAX shall equal 2CHAR_BIT - 1.
Forward references: representations of types (6.2.6), conditional inclusion (6.10.1).
15) See 6.2.5.
-5.2.4.2.2 Characteristics of floating types
+
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 @@ -1573,19 +1634,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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) + fk nonnegative integers less than b (the significand digits) + A floating-point number (x) is defined by the following model:
p
- x = sb e (Sum) f k b-k ,
+ x = s be (Sum) fk b-k , emin <= e <= emax
k=1
- emin <= e <= emax
+
- In addition to normalized floating-point numbers ( f 1 > 0 if x != 0), floating types may be + In addition to normalized floating-point numbers ( f1 > 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 + numbers (x != 0, e = emin , f1 = 0) and unnormalized floating-point numbers (x != 0, + e > emin , f1 = 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 @@ -1609,8 +1671,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 + 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.
The rounding mode for floating-point addition is characterized by the implementation- @@ -1620,7 +1682,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 0 toward zero 1 to nearest 2 toward positive infinity - 3 toward negative infinity + 3 toward negative infinity + All other values for FLT_ROUNDS characterize implementation-defined rounding behavior.
@@ -1642,7 +1705,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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. + long double type. + All other negative values for FLT_EVAL_METHOD characterize implementation-defined behavior.
@@ -1651,19 +1715,26 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 those shown, with the same sign:
FLT_RADIX 2 +
FLT_MANT_DIG
DBL_MANT_DIG
LDBL_MANT_DIG
+
- ??? pmax log10 b if b is a power of 10 - ??? - ??? ???1 + pmax log10 b??? otherwise+ { pmax log10 b if b is a power of 10 + { + { [^1 + pmax log10 b^] otherwise + +
DECIMAL_DIG 10
+
- ??? p log10 b if b is a power of 10 - ??? - ??? ???( p - 1) log10 b??? otherwise+ { p log10 b if b is a power of 10 + { + { [_( p - 1) log10 b_] otherwise + +
FLT_DIG 6 DBL_DIG 10 LDBL_DIG 10 +
FLT_MIN_EXP DBL_MIN_EXP LDBL_MIN_EXP +
- ??? ???FLT_MIN_10_EXP -37 DBL_MIN_10_EXP -37 LDBL_MIN_10_EXP -37 +
FLT_MAX_EXP DBL_MAX_EXP LDBL_MAX_EXP +
FLT_MAX_10_EXP +37 DBL_MAX_10_EXP +37 LDBL_MAX_10_EXP +37 +
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:
FLT_MAX 1E+37 DBL_MAX 1E+37 LDBL_MAX 1E+37 +
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:
FLT_EPSILON 1E-5
DBL_EPSILON 1E-9
LDBL_EPSILON 1E-9
-
FLT_MIN 1E-37
DBL_MIN 1E-37
LDBL_MIN 1E-37
+
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back should be the identity function. @@ -1736,9 +1822,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 float:
6
- x = s16e (Sum) f k 16-k ,
+ x = s 16e (Sum) fk 16-k , -31 <= e <= +32
k=1
- -31 <= e <= +32
+
FLT_RADIX 16
@@ -1750,7 +1836,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
FLT_MIN_10_EXP -38
FLT_MAX_EXP +32
FLT_MAX 3.40282347E+38F
- FLT_MAX_10_EXP +38
+ FLT_MAX_10_EXP +38
+
EXAMPLE 2 The following describes floating-point representations that also meet the requirements for @@ -1758,22 +1845,24 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 <float.h> header for types float and double:
24
- x f = s2e (Sum) f k 2-k ,
+ xf = s 2e (Sum) fk 2-k , -125 <= e <= +128
k=1
- -125 <= e <= +128
+
53
- x d = s2e (Sum) f k 2-k ,
+ xd = s 2e (Sum) fk 2-k , -1021 <= e <= +1024
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_EPSILON 0X1P-23F // hex constant
+
@@ -1798,7 +1887,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
DBL_MAX_EXP +1024
DBL_MAX 1.7976931348623157E+308 // decimal constant
DBL_MAX 0X1.fffffffffffffP1023 // hex constant
- DBL_MAX_10_EXP +308
+ 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.
@@ -1829,9 +1919,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
limits are one less than shown here.
-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 @@ -1839,7 +1929,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 }
+ { expressionopt }
+
indicates an optional expression enclosed in braces.
When syntactic categories are referred to in the main text, they are not italicized and @@ -1847,9 +1938,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A summary of the language syntax is given in annex A.
-6.2 Concepts
+
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
@@ -1901,7 +1992,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(6.9.1), identifiers (6.4.2), name spaces of identifiers (6.2.3), macro replacement (6.10.3),
source file inclusion (6.10.2), statements (6.8).
-6.2.2 Linkages of identifiers
+
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.21) There are @@ -1949,7 +2040,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
23) As specified in 6.2.1, the later declaration might hide the prior declaration.
-6.2.3 Name spaces of identifiers
+
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. @@ -1977,7 +2068,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
24) There is only one name space for tags even though three are possible.
-6.2.4 Storage durations of objects
+
An object has a storage duration that determines its lifetime. There are three storage
durations: static, automatic, and allocated. Allocated storage is described in 7.20.3.
@@ -2028,7 +2119,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
embedded block prior to the declaration, leaves the scope of the declaration.
-6.2.5 Types
+
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
@@ -2245,9 +2336,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
arguments to functions, return values from functions, and members of unions.
-6.2.6 Representations of types
+
The representations of all types are unspecified except as stated in this subclause.
@@ -2299,11 +2390,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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.+ type unsigned char range from 0 to 2CHAR_BIT- 1.
41) 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.
@@ -2317,13 +2404,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
on values of type T may distinguish between them.
-6.2.6.2 Integer types
+
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 + power of 2 between 1 and 2N-1 , so that objects of that type shall be capable of + representing values from 0 to 2N - 1 using a pure binary representation; this shall be known as the value representation. The values of any padding bits are unspecified.44)
For signed integer types, the bits of the object representation shall be divided into three @@ -2337,8 +2424,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 modified in one of the following ways:
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, @@ -2432,11 +2519,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE Given the following two file scope declarations:
int f(int (*)(), double (*)[3]);
- int f(int (*)(char *), double (*)[]);
+ int f(int (*)(char *), double (*)[]);
+
The resulting composite type for the function is:
- int f(int (*)(char *), double (*)[3]);+ int f(int (*)(char *), double (*)[3]); +
46) Two types need not be identical to be compatible. @@ -2444,7 +2533,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
47) As specified in 6.2.1, the later declaration might hide the prior declaration.
-6.3 Conversions
+
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 @@ -2456,9 +2545,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 representation.
Forward references: cast operators (6.5.4).
-6.3.1 Arithmetic operands
+
Every integer type has an integer conversion rank defined as follows:
When any scalar value is converted to _Bool, the result is 0 if the value compares equal
to 0; otherwise, the result is 1.
-6.3.1.3 Signed and unsigned integers
+
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. @@ -2528,7 +2617,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
49) The rules describe arithmetic on the mathematical value, not the value of a given type of expression.
-6.3.1.4 Real floating and integer
+
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
@@ -2549,7 +2638,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
range of portable real floating values is (-1, Utype_MAX+1).
-6.3.1.5 Real floating types
+
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
@@ -2564,12 +2653,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
+
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
@@ -2579,7 +2668,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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 @@ -2590,32 +2679,35 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 and complex otherwise. This pattern is called the usual arithmetic conversions:
-
- First, if the corresponding real type of either operand is long double, the other +
An lvalue is an expression with an object type or an incomplete type other than void;53)
if an lvalue does not designate an object when it is evaluated, the behavior is undefined.
@@ -2683,7 +2775,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
designator and violates the constraint in 6.5.3.4.
-6.3.2.2 void
+
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
@@ -2691,7 +2783,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
expression, its value or designator is discarded. (A void expression is evaluated for its
side effects.)
-6.3.2.3 Pointers
+
A pointer to void may be converted to or from a pointer to any incomplete or object
type. A pointer to any incomplete or object type may be converted to a pointer to void
@@ -2748,7 +2840,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
correctly aligned for a pointer to type C.
-6.4 Lexical elements
+
@@ -2765,7 +2857,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character-constant
string-literal
punctuator
- each non-white-space character that cannot be one of the above
+ each non-white-space character that cannot be one of the above
+
Each preprocessing token that is converted to a token shall have the lexical form of a
@@ -2820,7 +2913,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
occur in source files.
-6.4.1 Keywords
+
@@ -2834,7 +2927,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
default inline struct _Imaginary
do int switch
double long typedef
- else register union
+ else register union
+
The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as @@ -2849,9 +2943,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
59) One possible specification for imaginary types appears in annex G.
-6.4.2 Identifiers
+
@@ -2869,7 +2963,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+ 0 1 2 3 4 5 6 7 8 9
+
An identifier is a sequence of nondigit characters (including the underscore _, the @@ -2890,7 +2985,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 - Implementation limits +
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
@@ -2909,13 +3004,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Extended characters may produce a long external identifier.
-6.4.2.2 Predefined identifiers
+
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";+ static const char __func__[] = "function-name"; + appeared, where function-name is the name of the lexically-enclosing function.61)
This name is encoded as if the implicit declaration had been written in the source @@ -2929,10 +3025,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 { printf("%s\n", __func__); /* ... */ - } + } + Each time the function is called, it will print to the standard output stream:
- myfunc+ myfunc +
Forward references: function definitions (6.9.1).
@@ -2946,7 +3044,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
identifier is explicitly declared using the name __func__, the behavior is undefined.
-6.4.3 Universal character names
+
@@ -2955,7 +3053,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
\U hex-quad hex-quad
hex-quad:
hexadecimal-digit hexadecimal-digit
- hexadecimal-digit hexadecimal-digit
+ hexadecimal-digit hexadecimal-digit
+
A universal character name shall not specify a character whose short identifier is less than @@ -2985,7 +3084,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
63) Short identifiers for characters were first specified in ISO/IEC 10646-1/AMD9:1997.
-6.4.4 Constants
+
@@ -2993,7 +3092,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
integer-constant
floating-constant
enumeration-constant
- character-constant
+ character-constant
+
Each constant shall have a type and the value of a constant shall be in the range of @@ -3002,15 +3102,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Each constant has a type, determined by its form and value, as detailed later.
-6.4.4.1 Integer constants
+
integer-constant:
- decimal-constant integer-suffixopt
- octal-constant integer-suffixopt
- hexadecimal-constant integer-suffixopt
+ decimal-constant integer-suffixopt
+ octal-constant integer-suffixopt
+ hexadecimal-constant integer-suffixopt
decimal-constant:
nonzero-digit
decimal-constant digit
@@ -3031,16 +3131,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
a b c d e f
A B C D E F
integer-suffix:
- unsigned-suffix long-suffixopt
+ unsigned-suffix long-suffixopt
unsigned-suffix long-long-suffix
- long-suffix unsigned-suffixopt
- long-long-suffix unsigned-suffixopt
+ 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
+ ll LL
+
An integer constant begins with a digit, but has no period or exponent part. It may have a @@ -3059,38 +3160,69 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The type of an integer constant is the first of the corresponding list in which its value can be represented. -
- 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 +
| Suffix | Decimal Constant | Octal or Hexadecimal Constant + |
|---|---|---|
| none + | +int +long int +long long int ++ | +int +unsigned int +long int +unsigned long int +long long int +unsigned long long int ++ |
| u or U + | +unsigned int +unsigned long int +unsigned long long int ++ | +unsigned int +unsigned long int +unsigned long long int ++ |
| l or L + | +long int +long long int ++ | +long int +unsigned long int +long long int +unsigned long long int ++ |
| Both u or U and l or L + | +unsigned long int +unsigned long long int ++ | +unsigned long int +unsigned long long int ++ |
| ll or LL + | +long long int ++ | +long long int +unsigned long long int ++ |
| Both u or U and ll or LL + | +unsigned long long int ++ | +unsigned long long int ++ |
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
@@ -3101,7 +3233,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
its list and has no extended integer type, then the integer constant has no type.
-6.4.4.2 Floating constants
+
@@ -3110,36 +3242,37 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 decimal-floating-constant hexadecimal-floating-constant decimal-floating-constant: - fractional-constant exponent-partopt floating-suffixopt - digit-sequence exponent-part floating-suffixopt + 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 + binary-exponent-part floating-suffixopt hexadecimal-prefix hexadecimal-digit-sequence - binary-exponent-part floating-suffixopt + binary-exponent-part floating-suffixopt fractional-constant: - digit-sequenceopt . digit-sequence + digit-sequenceopt . digit-sequence digit-sequence . exponent-part: - e signopt digit-sequence - E signopt digit-sequence + 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-sequenceopt . hexadecimal-digit-sequence hexadecimal-digit-sequence . binary-exponent-part: - p signopt digit-sequence - P signopt digit-sequence + 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 + f l F L +
A floating constant has a significand part that may be followed by an exponent part and a @@ -3168,7 +3301,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
The implementation should produce a diagnostic message if a hexadecimal constant
cannot be represented exactly in its evaluation format; the implementation should then
@@ -3189,18 +3322,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
floating constants (see 7.20.1.3).
-6.4.4.3 Enumeration constants
+
enumeration-constant:
- identifier
+ identifier
+
An identifier declared as an enumeration constant has type int.
Forward references: enumeration specifiers (6.7.2.2).
-6.4.4.4 Character constants
+
@@ -3229,7 +3363,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 \ octal-digit octal-digit octal-digit hexadecimal-escape-sequence: \x hexadecimal-digit - hexadecimal-escape-sequence hexadecimal-digit + hexadecimal-escape-sequence hexadecimal-digit +
An integer character constant is a sequence of one or more multibyte characters enclosed
@@ -3248,7 +3383,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
question mark ? \?
backslash \ \\
octal character \octal digits
- hexadecimal character \x hexadecimal digits
+ hexadecimal character \x hexadecimal digits
+
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 \\.
@@ -3332,20 +3468,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the result is not a token and a diagnostic is required. See ''future language directions'' (6.11.4).
-6.4.5 String literals
+
string-literal:
- " s-char-sequenceopt "
- L" s-char-sequenceopt "
+ " s-char-sequenceopt "
+ L" s-char-sequenceopt "
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
+ escape-sequence
+
A character string literal is a sequence of zero or more multibyte characters enclosed in @@ -3384,7 +3521,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE This pair of adjacent character string literals
- "\x12" "3"+ "\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. @@ -3397,7 +3535,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 it by a \0 escape sequence. -
@@ -3408,7 +3546,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
? : ; ...
= *= /= %= += -= <<= >>= &= ^= |=
, # ##
- <: :> <% %> %: %:%:
+ <: :> <% %> %: %:%:
+
A punctuator is a symbol that has independent syntactic and semantic significance. @@ -3420,10 +3559,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
In all aspects of the language, the six tokens67)
- <: :> <% %> %: %:%:+ <: :> <% %> %: %:%: + behave, respectively, the same as the six tokens
- [ ] { } # ##
+ [ ] { } # ##
+
except for their spelling.68)
Forward references: expressions (6.5), declarations (6.7), preprocessing directives
(6.10), statements (6.8).
@@ -3435,7 +3576,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
interchanged.
-6.4.7 Header names
+
@@ -3453,7 +3594,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
q-char-sequence q-char
q-char:
any member of the source character set except
- the new-line character and "
+ the new-line character and "
+
The sequences in both forms of header names are mapped in an implementation-defined @@ -3474,13 +3616,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
0x3<1/a.h>1e2
#include <1/a.h>
- #define const.member@$
+ #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}{@}{$}
+ {#}{define} {const}{.}{member}{@}{$}
+
Forward references: source file inclusion (6.10.2). @@ -3490,7 +3634,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
70) For an example of a header name preprocessing token used in a #pragma directive, see 6.10.9.
-6.4.8 Preprocessing numbers
+
@@ -3503,7 +3647,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
pp-number E sign
pp-number p sign
pp-number P sign
- pp-number .
+ pp-number .
+
A preprocessing number begins with a digit optionally preceded by a period (.) and may
@@ -3520,7 +3665,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-6.4.9 Comments
+
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 @@ -3545,7 +3690,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 glue(/,/) k(); // syntax error, not comment /*//*/ l(); // equivalent to l(); m = n//**/o - + p; // equivalent to m = n + p; + + p; // equivalent to m = n + p; + @@ -3556,7 +3702,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
71) Thus, /* ... */ comments do not nest.
-6.5 Expressions
+
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 @@ -3627,9 +3773,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
i = ++i + 1;
a[i++] = i;
+
while allowing
+
i = i + 1;
- a[i] = i;
+ a[i] = i;
+
74) The syntax specifies the precedence of operators in the evaluation of an expression, which is the same
@@ -3640,9 +3789,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
+ 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.
75) Allocated objects have no declared type.
@@ -3656,7 +3804,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
documented.
-6.5.1 Primary expressions
+
@@ -3664,7 +3812,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
identifier
constant
string-literal
- ( expression )
+ ( expression )
+
An identifier is a primary expression, provided it has been declared as designating an @@ -3686,20 +3835,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
79) Thus, an undeclared identifier is a violation of the syntax.
-6.5.2 Postfix operators
+
postfix-expression:
primary-expression
postfix-expression [ expression ]
- postfix-expression ( argument-expression-listopt )
+ postfix-expression ( argument-expression-listopt )
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
- ( type-name ) { initializer-list , }
+ ( type-name ) { initializer-list , }
+
@@ -3708,9 +3858,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
argument-expression-list:
assignment-expression
- argument-expression-list , assignment-expression
+ argument-expression-list , assignment-expression
+
-One of the expressions shall have type ''pointer to object type'', the other expression shall @@ -3734,7 +3885,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE Consider the array object defined by the declaration
- int x[3][5];+ 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 @@ -3747,7 +3899,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 (6.5.3.2), array declarators (6.7.5.2). -
The expression that denotes the called function80) shall have type pointer to function @@ -3819,7 +3971,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE In the function call
- (*pf[f1()]) (f2(), f3() + f4())+ (*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. @@ -3835,7 +3988,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 adjusted to have a pointer type as described in 6.9.1. -
The first operand of the . operator shall have a qualified or unqualified structure or union @@ -3875,7 +4028,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 struct s { int i; const int ci; }; struct s s; const struct s cs; - volatile struct s vs; + volatile struct s vs; + the various members have the types:
s.i int
@@ -3883,7 +4037,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
cs.i const int
cs.ci const int
vs.i volatile int
- vs.ci volatile const int
+ vs.ci volatile const int
+
@@ -3910,7 +4065,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
/* ... */
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; };
@@ -3929,7 +4085,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
} 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).
@@ -3945,7 +4102,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
its operand), the expression (&E)->MOS is the same as E.MOS.
-6.5.2.4 Postfix increment and decrement operators
+
The operand of the postfix increment or decrement operator shall have qualified or @@ -3964,7 +4121,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 it).
Forward references: additive operators (6.5.6), compound assignment (6.5.16.2).
-6.5.2.5 Compound literals
+
The type name shall specify an object type or an array of unknown size, but not a variable @@ -4003,7 +4160,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 1 The file scope definition
- int *p = (int []){2, 4};
+ 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.
@@ -4017,7 +4175,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
/*...*/
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.
@@ -4027,16 +4186,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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});
+ (struct point){.x=3, .y=4});
+
Or, if drawline instead expected pointers to struct point:
drawline(&(struct point){.x=1, .y=1},
- &(struct point){.x=3, .y=4});
+ &(struct point){.x=3, .y=4});
+
EXAMPLE 4 A read-only compound literal can be specified through constructions like:
- (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}
+ (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}
+
@@ -4047,7 +4209,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
"/tmp/fileXXXXXX"
(char []){"/tmp/fileXXXXXX"}
- (const 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.
@@ -4056,7 +4219,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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"
+ (const char []){"abc"} == "abc"
+
might yield 1 if the literals' storage is shared.
@@ -4066,7 +4230,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
struct int_list { int car; struct int_list *cdr; };
struct int_list endless_zeros = {0, &endless_zeros};
- eval(endless_zeros);
+ eval(endless_zeros);
+
EXAMPLE 8 Each compound literal creates only a single object in a given scope: @@ -4080,7 +4245,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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.
Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the
@@ -4100,7 +4266,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the same or overlapping representations.
-6.5.3 Unary operators
+
@@ -4112,9 +4278,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
sizeof unary-expression
sizeof ( type-name )
unary-operator: one of
- & * + - ~ !
+ & * + - ~ !
+
-The operand of the prefix increment or decrement operator shall have qualified or @@ -4130,7 +4297,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 operand is decremented.
Forward references: additive operators (6.5.6), compound assignment (6.5.16.2).
-6.5.3.2 Address and indirection operators
+
The operand of the unary & operator shall be either a function designator, the result of a
@@ -4168,7 +4335,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
end of its lifetime.
-6.5.3.3 Unary arithmetic operators
+
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
@@ -4196,7 +4363,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-6.5.3.4 The sizeof operator
+
The sizeof operator shall not be applied to an expression that has function type or an @@ -4224,14 +4391,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 allocate and return a pointer to void. For example:
extern void *alloc(size_t);
- double *dp = alloc(sizeof *dp);
+ 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.
EXAMPLE 2 Another use of the sizeof operator is to compute the number of elements in an array:
- sizeof array / sizeof array[0]+ sizeof array / sizeof array[0] +
EXAMPLE 3 In this example, the size of a variable length array is computed and returned from a @@ -4242,7 +4411,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 { char b[n+3]; // variable length array return sizeof b; // execution time sizeof - } + } + @@ -4253,7 +4423,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 size_t size; size = fsize3(10); // fsize3 returns 13 return 0; - } + } +
Forward references: common definitions <stddef.h> (7.17), declarations (6.7),
structure and union specifiers (6.7.2.1), type names (6.7.6), array declarators (6.7.5.2).
@@ -4263,13 +4434,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size of the adjusted (pointer) type (see 6.9.1).
-6.5.4 Cast operators
+
cast-expression:
unary-expression
- ( type-name ) cast-expression
+ ( type-name ) cast-expression
+
Unless the type name specifies a void type, the type name shall specify qualified or
@@ -4299,7 +4471,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
unqualified version of the type.
-6.5.5 Multiplicative operators
+
@@ -4307,7 +4479,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
- multiplicative-expression % cast-expression
+ multiplicative-expression % cast-expression
+
Each of the operands shall have arithmetic type. The operands of the % operator shall @@ -4330,14 +4503,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
90) This is often called ''truncation toward zero''.
-6.5.6 Additive operators
+
additive-expression:
multiplicative-expression
additive-expression + multiplicative-expression
- additive-expression - multiplicative-expression
+ additive-expression - multiplicative-expression
+
For addition, either both operands shall have arithmetic type, or one operand shall be a
@@ -4411,7 +4585,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
p += 1; // p == &a[1]
(*p)[2] = 99; // a[1][2] == 99
n = p - a; // n == 1
- }
+ }
+
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.
@@ -4430,14 +4605,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
element'' requirements.
-6.5.7 Bitwise shift operators
+
shift-expression:
additive-expression
shift-expression << additive-expression
- shift-expression >> additive-expression
+ shift-expression >> additive-expression
+
Each of the operands shall have integer type.
@@ -4463,7 +4639,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
@@ -4472,7 +4648,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
- relational-expression >= shift-expression
+ relational-expression >= shift-expression
+
One of the following shall hold:
@@ -4514,14 +4691,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
means (a<b)<c; in other words, ''if a is less than b, compare 1 to c; otherwise, compare 0 to c''.
-6.5.9 Equality operators
+
equality-expression:
relational-expression
equality-expression == relational-expression
- equality-expression != relational-expression
+ equality-expression != relational-expression
+
One of the following shall hold:
@@ -4574,13 +4752,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
behavior.
-6.5.10 Bitwise AND operator
+
AND-expression:
equality-expression
- AND-expression & equality-expression
+ AND-expression & equality-expression
+
Each of the operands shall have integer type.
@@ -4597,13 +4776,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-6.5.11 Bitwise exclusive OR operator
+
exclusive-OR-expression:
AND-expression
- exclusive-OR-expression ^ AND-expression
+ exclusive-OR-expression ^ AND-expression
+
Each of the operands shall have integer type.
@@ -4615,13 +4795,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
inclusive-OR-expression:
exclusive-OR-expression
- inclusive-OR-expression | exclusive-OR-expression
+ inclusive-OR-expression | exclusive-OR-expression
+
Each of the operands shall have integer type.
@@ -4634,13 +4815,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
operands is set).
-6.5.13 Logical AND operator
+
logical-AND-expression:
inclusive-OR-expression
- logical-AND-expression && inclusive-OR-expression
+ logical-AND-expression && inclusive-OR-expression
+
Each of the operands shall have scalar type.
@@ -4653,13 +4835,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
there is a sequence point after the evaluation of the first operand. If the first operand
compares equal to 0, the second operand is not evaluated.
-6.5.14 Logical OR operator
+
logical-OR-expression:
logical-AND-expression
- logical-OR-expression || logical-AND-expression
+ logical-OR-expression || logical-AND-expression
+
Each of the operands shall have scalar type.
@@ -4673,13 +4856,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
unequal to 0, the second operand is not evaluated.
-6.5.15 Conditional operator
+
conditional-expression:
logical-OR-expression
- logical-OR-expression ? expression : conditional-expression
+ logical-OR-expression ? expression : conditional-expression
+
The first operand shall have scalar type. @@ -4730,7 +4914,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 const int *c_ip; volatile int *v_ip; int *ip; - const char *c_cp; + 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):
@@ -4739,14 +4924,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
c_ip v_ip const volatile int *
vp c_cp const void *
ip c_ip const int *
- vp ip void *
+ vp ip void *
+
95) A conditional expression does not yield an lvalue.
-6.5.16 Assignment operators
+
@@ -4754,7 +4940,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
conditional-expression
unary-expression assignment-operator assignment-expression
assignment-operator: one of
- = *= /= %= += -= <<= >>= &= ^= |=
+ = *= /= %= += -= <<= >>= &= ^= |=
+
An assignment operator shall have a modifiable lvalue as its left operand.
@@ -4772,7 +4959,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
behavior is undefined.
-6.5.16.1 Simple assignment
+
One of the following shall hold:96)
@@ -4807,7 +4994,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
@@ -4824,7 +5012,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
char c;
int i;
long l;
- l = (c = i);
+ 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.
@@ -4837,7 +5026,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
const char c = 'A';
cpp = &p; // constraint violation
*cpp = &c; // valid
- *p = 0; // 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.
@@ -4849,7 +5039,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
not volatile from the type int volatile * const).
-6.5.16.2 Compound assignment
+
For the operators += and -= only, either the left operand shall be a pointer to an object
@@ -4864,13 +5054,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
expression E1 = E1 op (E2) only in that the lvalue E1 is evaluated only once.
-6.5.17 Comma operator
+
expression:
assignment-expression
- expression , assignment-expression
+ expression , assignment-expression
+
The left operand of a comma operator is evaluated as a void expression; there is a @@ -4883,7 +5074,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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)+ f(a, (t=3, t+2), c) + the function has three arguments, the second of which has the value 5.
Forward references: initialization (6.7.8). @@ -4897,12 +5089,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
97) A comma operator does not yield an lvalue.
-6.6 Constant expressions
+
constant-expression:
- conditional-expression
+ conditional-expression
+
A constant expression can be evaluated during translation rather than runtime, and @@ -4979,27 +5172,29 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
100) Thus, in the following initialization,
- static int i = 2 || 1 / 0;
+ static int i = 2 || 1 / 0;
+
the expression is a valid integer constant expression with value one.
-6.7 Declarations
+
declaration:
- declaration-specifiers init-declarator-listopt ;
+ declaration-specifiers init-declarator-listopt ;
declaration-specifiers:
- storage-class-specifier declaration-specifiersopt
- type-specifier declaration-specifiersopt
- type-qualifier declaration-specifiersopt
- function-specifier declaration-specifiersopt
+ storage-class-specifier declaration-specifiersopt
+ type-specifier declaration-specifiersopt
+ type-qualifier declaration-specifiersopt
+ function-specifier declaration-specifiersopt
init-declarator-list:
init-declarator
init-declarator-list , init-declarator
init-declarator:
declarator
- declarator = initializer
+ declarator = initializer
+
A declaration shall declare at least a declarator (other than the parameters of a function or @@ -5041,7 +5236,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
101) Function definitions have a different syntax, described in 6.9.1.
-6.7.1 Storage-class specifiers
+
@@ -5050,7 +5245,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
extern
static
auto
- register
+ register
+
At most, one storage-class specifier may be given in the declaration specifiers in a
@@ -5089,7 +5285,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
register is sizeof.
-6.7.2 Type specifiers
+
@@ -5107,7 +5303,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
_Complex
struct-or-union-specifier *
enum-specifier
- typedef-name
+ typedef-name
+
At least one type specifier shall be given in the declaration specifiers in each declaration, @@ -5165,12 +5362,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
104) Freestanding implementations are not required to provide complex types. *
-6.7.2.1 Structure and union specifiers
+
struct-or-union-specifier:
- struct-or-union identifieropt { struct-declaration-list }
+ struct-or-union identifieropt { struct-declaration-list }
struct-or-union identifier
struct-or-union:
struct
@@ -5181,14 +5378,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
struct-declaration:
specifier-qualifier-list struct-declarator-list ;
specifier-qualifier-list:
- type-specifier specifier-qualifier-listopt
- type-qualifier specifier-qualifier-listopt
+ 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
+ declaratoropt : constant-expression
+
A structure or union shall not contain a member with incomplete or function type (hence, @@ -5277,15 +5475,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE After the declaration:
- struct s { int n; double d[]; };
+ 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]));
+ 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;
+ 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).
@@ -5295,21 +5496,25 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 + 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
- sizeof (struct s) >= offsetof(struct s, d) + sizeof (double)+ 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.
After the further declaration:
- struct ss { int n; };
+ struct ss { int n; };
+
the expressions:
sizeof (struct s) >= sizeof (struct ss)
- sizeof (struct s) >= offsetof(struct s, d)
+ sizeof (struct s) >= offsetof(struct s, d)
+
are always equal to 1.
If sizeof (double) is 8, then after the following code is executed: @@ -5317,20 +5522,24 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 struct s *s1; struct s *s2; s1 = malloc(sizeof (struct s) + 64); - s2 = malloc(sizeof (struct s) + 46); + 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;
+ struct { int n; double d[5]; } *s2;
+
Following the further successful assignments:
s1 = malloc(sizeof (struct s) + 10);
- s2 = malloc(sizeof (struct s) + 6);
+ s2 = malloc(sizeof (struct s) + 6);
+
they then behave as if the declarations were:
- struct { int n; double d[1]; } *s1, *s2;
+ struct { int n; double d[1]; } *s1, *s2;
+
and:
@@ -5338,10 +5547,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
dp = &(s1->d[0]); // valid
*dp = 42; // valid
dp = &(s2->d[0]); // valid
- *dp = 42; // undefined behavior
+ *dp = 42; // undefined behavior
+
The assignment:
- *s1 = *s2;+ *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. @@ -5362,20 +5573,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 layouts. -
enum-specifier:
- enum identifieropt { enumerator-list }
- enum identifieropt { enumerator-list , }
+ enum identifieropt { enumerator-list }
+ enum identifieropt { enumerator-list , }
enum identifier
enumerator-list:
enumerator
enumerator-list , enumerator
enumerator:
enumeration-constant
- enumeration-constant = constant-expression
+ enumeration-constant = constant-expression
+
The expression that defines the value of an enumeration constant shall be an integer
@@ -5409,7 +5621,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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 }.
@@ -5423,7 +5636,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
been seen.
-6.7.2.3 Tags
+
A specific type shall have its content defined at most once. @@ -5433,7 +5646,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A type specifier of the form
- enum identifier+ enum identifier + without an enumerator list shall only appear after the type it specifies is complete.
@@ -5447,13 +5661,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A type specifier of the form
- struct-or-union identifieropt { struct-declaration-list }
+ struct-or-union identifieropt { struct-declaration-list }
+
or
- enum identifier { enumerator-list }
+ enum identifier { enumerator-list }
+
or
- enum identifier { enumerator-list , }
+ enum identifier { enumerator-list , }
+
declares a structure, union, or enumerated type. The list defines the structure content,
@@ -5462,22 +5679,26 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A declaration of the form
- struct-or-union identifier ;+ struct-or-union identifier ; + specifies a structure or union type and declares the identifier as a tag of that type.113)
If a type specifier of the form
- struct-or-union identifier+ 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.113)
If a type specifier of the form
- struct-or-union identifier+ struct-or-union identifier + or
- enum identifier+ 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. @@ -5487,11 +5708,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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
- struct tnode s, *sp;+ 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 @@ -5509,19 +5732,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 int count; TNODE *left, *right; }; - TNODE s, *sp; + TNODE s, *sp; +
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
+ 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;+ 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. @@ -5542,14 +5768,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
113) A similar construction with enum does not exist.
-6.7.3 Type qualifiers
+
type-qualifier:
const
restrict
- volatile
+ volatile
+
Types other than pointer types derived from object or incomplete types shall not be @@ -5599,7 +5826,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 1 An object declared
- extern const volatile int real_time_clock;+ extern const volatile int real_time_clock; + may be modifiable by hardware, but cannot be assigned to, incremented, or decremented. @@ -5621,7 +5849,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 *'' + pi = a[0]; // invalid: a[0] has type ''const int *'' +
118) Both of these can occur through the use of typedefs.
-6.7.3.1 Formal definition of restrict
+
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. @@ -5681,7 +5910,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int * restrict a;
int * restrict b;
- extern int c[];
+ 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.
@@ -5692,7 +5922,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
{
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.
@@ -5707,7 +5938,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 extern int d[100]; f(50, d + 50, d); // valid f(50, d + 1, d); // undefined behavior - } + } +
EXAMPLE 3 The function parameter declarations @@ -5717,7 +5949,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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. @@ -5739,7 +5972,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 p1 = q2; // undefined behavior p2 = q2; // undefined behavior } - } + } + 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. @@ -5751,7 +5985,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 t.n = n; t.v = malloc(n * sizeof (float)); return t; - } + } +
function-specifier:
- inline
+ inline
+
Function specifiers shall be used only in the declaration of an identifier for a function.
@@ -5815,7 +6051,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
{
/* A translator may perform inline substitutions */
return is_fahr ? cels(temp) : fahr(temp);
- }
+ }
+
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
@@ -5843,24 +6080,24 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
duration are also distinct in each of the definitions.
-6.7.5 Declarators
+
declarator:
- pointeropt direct-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-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 [ type-qualifier-listopt * ]
direct-declarator ( parameter-type-list )
- direct-declarator ( identifier-listopt )
+ direct-declarator ( identifier-listopt )
pointer:
- * type-qualifier-listopt
- * type-qualifier-listopt pointer
+ * type-qualifier-listopt
+ * type-qualifier-listopt pointer
type-qualifier-list:
type-qualifier
type-qualifier-list type-qualifier
@@ -5872,10 +6109,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
parameter-list , parameter-declaration
parameter-declaration:
declaration-specifiers declarator
- declaration-specifiers abstract-declaratoropt
+ declaration-specifiers abstract-declaratoropt
identifier-list:
identifier
- identifier-list , identifier
+ identifier-list , identifier
+
Each declarator declares one identifier, and asserts that when an operand of the same @@ -5891,35 +6129,39 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
In the following subclauses, consider a declaration
- T D1+ 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.
If, in the declaration ''T D1'', D1 has the form
- identifier+ identifier + then the type specified for ident is T .
If, in the declaration ''T D1'', D1 has the form
- ( D )+ ( 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 +
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 incomplete type, either directly or via one or more typedefs.
Forward references: array declarators (6.7.5.2), type definitions (6.7.7).
-6.7.5.1 Pointer declarators
+
If, in the declaration ''T D1'', D1 has the form
- * type-qualifier-listopt D+ * 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. @@ -5932,7 +6174,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
const int *ptr_to_constant;
- int *const constant_ptr;
+ 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
@@ -5942,11 +6185,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
type ''pointer to int''.
typedef int *int_ptr;
- const int_ptr constant_ptr;
+ const int_ptr constant_ptr;
+
declares constant_ptr as an object that has type ''const-qualified pointer to int''.
-In addition to optional type qualifiers and the keyword static, the [ and ] may delimit @@ -5964,10 +6208,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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-listopt assignment-expressionopt ]
+ D[ static type-qualifier-listopt assignment-expression ]
D[ type-qualifier-list static assignment-expression ]
- D[ type-qualifier-listopt * ]
+ 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 ''.123)
(See 6.7.5.3 for the meaning of the optional type qualifiers and the keyword static.)
@@ -5997,14 +6242,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 1
- float fa[11], *afp[17];+ float fa[11], *afp[17]; + declares an array of float numbers and an array of pointers to float numbers.
EXAMPLE 2 Note the distinction between the declarations
extern int *x;
- extern int y[];
+ 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.
@@ -6022,7 +6269,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
p = a; // invalid: not compatible because 4 != 6
r = c; // compatible, but defined behavior only if
// n == 6 and m == n+1
- }
+ }
+
@@ -6053,7 +6301,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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 (6.7.5.3), function definitions (6.9.1), initialization (6.7.8). @@ -6064,7 +6313,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
124) Thus, * can be used only in function declarations that are not definitions (see 6.7.5.3).
-6.7.5.3 Function declarators (including prototypes)
+
A function declarator shall not specify a return type that is a function type or an array @@ -6081,11 +6330,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
If, in the declaration ''T D1'', D1 has the form
- D( parameter-type-list )+ D( parameter-type-list ) + or
- D( identifier-listopt )+ 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 ''. @@ -6147,7 +6398,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 1 The declaration
- int f(void), *fip(), (*pfi)();+ 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 @@ -6164,7 +6416,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 2 The declaration
- int (*apfi[3])(int *x, int *y);+ 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. @@ -6172,7 +6425,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 3 The declaration
- int (*fpfi(int (*)(long), int))(int, ...);+ 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 @@ -6196,7 +6450,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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; - } + } +
EXAMPLE 5 The following are all compatible function prototype declarators. @@ -6204,13 +6459,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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]); + 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]);
+ void f(double a[restrict static 3][5]);
+
(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.)
@@ -6226,25 +6483,26 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
127) If both function types are ''old style'', parameter types are not compared.
-6.7.6 Type names
+
type-name:
- specifier-qualifier-list abstract-declaratoropt
+ specifier-qualifier-list abstract-declaratoropt
abstract-declarator:
pointer
- pointeropt direct-abstract-declarator
+ pointeropt direct-abstract-declarator
direct-abstract-declarator:
( abstract-declarator )
- direct-abstract-declaratoropt [ type-qualifier-listopt
- assignment-expressionopt ]
- direct-abstract-declaratoropt [ static type-qualifier-listopt
+ direct-abstract-declaratoropt [ type-qualifier-listopt
+ assignment-expressionopt ]
+ direct-abstract-declaratoropt [ static type-qualifier-listopt
assignment-expression ]
- direct-abstract-declaratoropt [ type-qualifier-list static
+ direct-abstract-declaratoropt [ type-qualifier-list static
assignment-expression ]
- direct-abstract-declaratoropt [ * ]
- direct-abstract-declaratoropt ( parameter-type-listopt )
+ direct-abstract-declaratoropt [ * ]
+ direct-abstract-declaratoropt ( parameter-type-listopt )
+
In several contexts, it is necessary to specify a type. This is accomplished using a type
@@ -6260,7 +6518,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(e) int (*)[*]
(f) int *()
(g) int (*)(void)
- (h) int (*const [])(unsigned int, ...)
+ (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
@@ -6278,12 +6537,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
parameter specification'', rather than redundant parentheses around the omitted identifier.
-6.7.7 Type definitions
+
typedef-name:
- identifier
+ identifier
+
If a typedef name specifies a variably modified type then it shall have block scope. @@ -6297,7 +6557,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 synonym for the type so specified. That is, in the following declarations:
typedef T type_ident;
- type_ident D;
+ 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
@@ -6307,13 +6568,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 1 After
typedef int MILES, KLICKSP();
- typedef struct { double hi, lo; } range;
+ typedef struct { double hi, lo; } range;
+
the constructions
MILES distance;
extern KLICKSP *metricp;
range x;
- range z, *zp;
+ 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.
@@ -6322,7 +6585,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE 2 After the declarations
typedef struct s1 { int x; } t1, *tp1;
- typedef struct s2 { int x; } t2, *tp2;
+ 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
s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int.
@@ -6335,7 +6599,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
@@ -6346,7 +6611,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
in an inner scope by
t f(t (t));
- long 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.
@@ -6359,7 +6625,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
typedef void fv(int), (*pfv)(int);
void (*signal(int, void (*)(int)))(int);
fv *signal(int, fv *);
- pfv signal(int, pfv);
+ pfv signal(int, pfv);
+
EXAMPLE 5 If a typedef name denotes a variable length array type, the length of the array is fixed at the
@@ -6374,9 +6641,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int b[n]; // a and b are different sizes
for (int i = 1; i < n; i++)
a[i-1] = b[i];
- }
+ }
+
-6.7.8 Initialization
+
@@ -6385,8 +6653,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
{ initializer-list }
{ initializer-list , }
initializer-list:
- designationopt initializer
- initializer-list , designationopt initializer
+ designationopt initializer
+ initializer-list , designationopt initializer
designation:
designator-list =
designator-list:
@@ -6394,7 +6662,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
designator-list designator
designator:
[ constant-expression ]
- . identifier
+ . identifier
+
No initializer shall attempt to provide a value for an object not contained within the entity @@ -6411,14 +6680,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
If a designator has the form
- [ constant-expression ]+ [ 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.
If a designator has the form
- . identifier+ . 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. @@ -6515,13 +6786,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE 1 Provided that <complex.h> has been #included, the declarations
int i = 3.5;
- double complex c = 5 + 3 * I;
+ double complex c = 5 + 3 * I;
+
define and initialize i with the value 3 and c with the value 5.0 + i3.0.
EXAMPLE 2 The declaration
- int x[] = { 1, 3, 5 };
+ 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.
@@ -6532,7 +6805,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
{ 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
@@ -6540,7 +6814,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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].
@@ -6549,13 +6824,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int z[4][3] = {
{ 1 }, { 2 }, { 3 }, { 4 }
- };
+ };
+
initializes the first column of z as specified and initializes the rest with zeros.
EXAMPLE 5 The declaration
- struct { int a[3], b; } w[] = { { 1 }, 2 };
+ 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.
@@ -6570,7 +6847,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
{ 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
@@ -6584,7 +6862,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
1, 0, 0, 0, 0, 0,
2, 3, 0, 0, 0, 0,
4, 5, 6
- };
+ };
+
or by:
short q[4][3][2] = {
@@ -6598,7 +6877,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
{ 4, 5 },
{ 6 },
}
- };
+ };
+
in a fully bracketed form.
Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to @@ -6608,27 +6888,33 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE 7 One form of initialization that completes array types involves typedef names. Given the declaration
- typedef int A[]; // OK - declared with block scope+ typedef int A[]; // OK - declared with block scope + the declaration
- A a = { 1, 2 }, b = { 3, 4, 5 };
+ A a = { 1, 2 }, b = { 3, 4, 5 };
+
is identical to
- int a[] = { 1, 2 }, b[] = { 3, 4, 5 };
+ int a[] = { 1, 2 }, b[] = { 3, 4, 5 };
+
due to the rules for incomplete types.
EXAMPLE 8 The declaration
- char s[] = "abc", t[3] = "abc";+ 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' };
+ t[] = { 'a', 'b', 'c' };
+
The contents of the arrays are modifiable. On the other hand, the declaration
- char *p = "abc";+ 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. @@ -6641,19 +6927,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 const char *nm[] = { [member_two] = "member two", [member_one] = "member one", - }; + }; +
EXAMPLE 10 Structure members can be initialized to nonzero values without depending on their order:
- div_t answer = { .quot = 2, .rem = -1 };
+ div_t answer = { .quot = 2, .rem = -1 };
+
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 };
+ { [0].a = {1}, [1].a[0] = 2 };
+
EXAMPLE 12 Space can be ''allocated'' from both ends of an array by using a single designator: @@ -6661,14 +6950,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int a[MAX] = {
1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
- };
+ };
+
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.
EXAMPLE 13 Any member of a union can be initialized:
- union { /* ... */ } u = { .any_member = 42 };
+ union { /* ... */ } u = { .any_member = 42 };
+
Forward references: common definitions <stddef.h> (7.17). @@ -6690,7 +6981,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
133) In particular, the evaluation order need not be the same as the order of subobject initialization.
-6.8 Statements and blocks
+
@@ -6700,7 +6991,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
expression-statement
selection-statement
iteration-statement
- jump-statement
+ jump-statement
+
A statement specifies an action to be performed. Except as indicated, statements are @@ -6722,14 +7014,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
labeled-statement:
identifier : statement
case constant-expression : statement
- default : statement
+ default : statement
+
A case or default label shall appear only in a switch statement. Further @@ -6744,28 +7037,30 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 them.
Forward references: the goto statement (6.8.6.1), the switch statement (6.8.4.2).
-6.8.2 Compound statement
+
compound-statement:
- { block-item-listopt }
+ { block-item-listopt }
block-item-list:
block-item
block-item-list block-item
block-item:
declaration
- statement
+ statement
+
A compound statement is a block.
-6.8.3 Expression and null statements
+
expression-statement:
- expressionopt ;
+ expressionopt ;
+
The expression in an expression statement is evaluated as a void expression for its side @@ -6779,7 +7074,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int p(int);
/* ... */
- (void)p(0);
+ (void)p(0);
+
@@ -6790,7 +7086,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
char *s;
/* ... */
while (*s++ != '\0')
- ;
+ ;
+
a null statement is used to supply an empty loop body to the iteration statement.
@@ -6807,7 +7104,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 } /* ... */ end_loop1: ; - } + } +
Forward references: iteration statements (6.8.5). @@ -6815,14 +7113,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
134) Such as assignments, and function calls which have side effects.
-6.8.4 Selection statements
+
selection-statement:
if ( expression ) statement
if ( expression ) statement else statement
- switch ( expression ) statement
+ switch ( expression ) statement
+
A selection statement selects among a set of statements depending on the value of a
@@ -6832,7 +7131,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
The controlling expression of an if statement shall have scalar type.
@@ -6847,7 +7146,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
An else is associated with the lexically nearest preceding if that is allowed by the
syntax.
-6.8.4.2 The switch statement
+
The controlling expression of a switch statement shall have integer type. @@ -6876,7 +7175,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
As discussed in 5.2.4.1, the implementation may limit the number of case values in a
switch statement.
@@ -6897,7 +7196,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
/* 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.
@@ -6908,15 +7208,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
default label associated with the switch that is in the block containing the declaration.
-6.8.5 Iteration statements
+
iteration-statement:
while ( expression ) statement
do statement while ( expression ) ;
- for ( expressionopt ; expressionopt ; expressionopt ) statement
- for ( declaration expressionopt ; expressionopt ) statement
+ for ( expressionopt ; expressionopt ; expressionopt ) statement
+ for ( declaration expressionopt ; expressionopt ) statement
+
The controlling expression of an iteration statement shall have scalar type.
@@ -6943,21 +7244,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
statement is not evaluated before entering the loop body, nor is clause-1 of a for statement.
-6.8.5.1 The while statement
+
The evaluation of the controlling expression takes place before each execution of the loop
body.
-6.8.5.2 The do statement
+
The evaluation of the controlling expression takes place after each execution of the loop
body.
-6.8.5.3 The for statement
+
The statement
- for ( clause-1 ; expression-2 ; expression-3 ) 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 @@ -6976,7 +7278,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 specifies an operation (such as incrementing) that is performed after each iteration. -
@@ -6984,7 +7286,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
goto identifier ;
continue ;
break ;
- return expressionopt ;
+ return expressionopt ;
+
A jump statement causes an unconditional jump to another place.
@@ -6994,7 +7297,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-6.8.6.1 The goto statement
+
The identifier in a goto statement shall name a label located somewhere in the enclosing @@ -7012,10 +7315,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
/* ... */
goto first_time;
for (;;) {
-
// determine next operation
/* ... */
if (need to reinitialize) {
@@ -7027,8 +7330,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
continue;
}
// handle other operations
- /* ... */
+ /* ... */
}
+
@@ -7046,10 +7350,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
lab4:
a[j] = 6.6;
}
- goto lab4; // invalid: going INTO scope of VLA.
+ goto lab4; // invalid: going INTO scope of VLA.
+
-6.8.6.2 The continue statement
+
A continue statement shall appear only in or as a loop body. @@ -7058,13 +7363,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 (/* ... */) {
+ 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;.138)
@@ -7072,7 +7378,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
138) Following the contin: label is a null statement.
-6.8.6.3 The break statement
+
A break statement shall appear only in or as a switch body or loop body.
@@ -7085,7 +7391,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-6.8.6.4 The return statement
+
A return statement with an expression shall not appear in a function whose return type
@@ -7119,7 +7425,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
return g.u1.f2;
}
/* ... */
- g.u2.f3 = f();
+ 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).
@@ -7135,7 +7442,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
range and precision.
-6.9 External definitions
+
@@ -7144,7 +7451,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
translation-unit external-declaration
external-declaration:
function-definition
- declaration
+ declaration
+
The storage-class specifiers auto and register shall not appear in the declaration
@@ -7180,15 +7488,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
external definition for it.
-6.9.1 Function definitions
+
function-definition:
- declaration-specifiers declarator declaration-listopt compound-statement
+ declaration-specifiers declarator declaration-listopt compound-statement
declaration-list:
declaration
- declaration-list declaration
+ declaration-list declaration
+
The identifier declared in a function definition (which is the name of the function) shall @@ -7249,11 +7558,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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; }
+ { return a > b ? a : b; }
+
is the function body. The following similar definition uses the identifier-list form for the parameter
declarations:
@@ -7266,7 +7577,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
@@ -7276,21 +7588,24 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int f(void);
/* ... */
- g(f);
+ 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)(); ... */
- }
+ }
+
142) See ''future language directions'' (6.11.7).
-6.9.2 External object definitions
+
If the declaration of an identifier for an object has file scope and an initializer, the @@ -7346,23 +7662,25 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 + extern int i5; // refers to previous, whose linkage is internal +
EXAMPLE 2 If at the end of the translation unit containing
- int i[];+ 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. -
preprocessing-file:
- groupopt
+ groupopt
group:
group-part
group group-part
@@ -7372,46 +7690,47 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
text-line
# non-directive
if-section:
- if-group elif-groupsopt else-groupopt endif-line
+ 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
+ # 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
+ # elif constant-expression new-line groupopt
else-group:
- # else new-line groupopt
+ # else new-line groupopt
endif-line:
# endif new-line
control-line:
# include pp-tokens new-line
# define identifier replacement-list new-line
- # define identifier lparen identifier-listopt )
+ # 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
+ # error pp-tokensopt new-line
+ # pragma pp-tokensopt new-line
# new-line
text-line:
- pp-tokensopt new-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-tokensopt
pp-tokens:
preprocessing-token
pp-tokens preprocessing-token
new-line:
- the new-line character
+ the new-line character
+
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the @@ -7450,7 +7769,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE In:
#define EMPTY
- EMPTY # include <file.h>
+ 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.
@@ -7462,7 +7782,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
# character string literal creation operator in 6.10.3.2, for example).
-The expression that controls conditional inclusion shall be an integer constant expression @@ -7475,10 +7795,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
- defined identifier+ defined identifier + or
- defined ( identifier )+ defined ( identifier ) + which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is 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. @@ -7490,8 +7812,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Preprocessing directives of the forms
- # if constant-expression new-line groupopt - # elif constant-expression new-line groupopt+ # if constant-expression new-line groupopt + # elif constant-expression new-line groupopt + check whether the controlling constant expression evaluates to nonzero.
Prior to evaluation, macro invocations in the list of preprocessing tokens that will become @@ -7519,8 +7842,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
- # ifdef identifier new-line groupopt - # ifndef identifier new-line groupopt+ # 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. @@ -7546,8 +7870,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
146) 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)
+
147) As indicated by the syntax, a preprocessing token shall not follow a #else or #endif directive
@@ -7555,7 +7881,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
including within a preprocessing directive.
-6.10.2 Source file inclusion
+
A #include directive shall identify a header or source file that can be processed by the @@ -7564,7 +7890,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A preprocessing directive of the form
- # include <h-char-sequence> new-line+ # 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 @@ -7576,19 +7903,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
- # include "q-char-sequence" new-line+ # 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 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+ # include <h-char-sequence> new-line + with the identical contained sequence (including > characters, if any) from the original directive.
A preprocessing directive of the form
- # include pp-tokens new-line+ # 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 @@ -7610,7 +7940,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following:
#include <stdio.h>
- #include "myprog.h"
+ #include "myprog.h"
+
EXAMPLE 2 This illustrates macro-replaced #include directives: @@ -7627,7 +7958,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #else #define INCFILE "versN.h" #endif - #include INCFILE + #include INCFILE +
Forward references: macro replacement (6.10.3).
@@ -7636,7 +7968,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
phases in 5.1.1.2); thus, an expansion that results in two string literals is an invalid directive.
-6.10.3 Macro replacement
+
Two replacement lists are identical if and only if the preprocessing tokens in both have @@ -7679,7 +8011,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A preprocessing directive of the form
- # define identifier replacement-list new-line+ # define identifier replacement-list new-line + defines an object-like macro that causes each subsequent instance of the macro name149) 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 @@ -7687,9 +8020,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A preprocessing directive of the form
- # define identifier lparen identifier-listopt ) 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
+ # 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
@@ -7726,7 +8060,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
150) Despite the name, a non-directive is a preprocessing directive.
-6.10.3.1 Argument substitution
+
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
@@ -7740,7 +8074,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
were a parameter, and the variable arguments shall form the preprocessing tokens used to
replace it.
-6.10.3.2 The # operator
+
Each # preprocessing token in the replacement list for a function-like macro shall be
@@ -7764,7 +8098,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
## operators is unspecified.
-6.10.3.3 The ## operator
+
A ## preprocessing token shall not occur at the beginning or at the end of a replacement @@ -7795,14 +8129,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #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"; + // 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"
+ "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.
@@ -7814,7 +8150,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
exist only within translation phase 4.
-
After all parameters in the replacement list have been substituted and # and ##
processing has taken place, all placemarker preprocessing tokens are removed. Then, the
@@ -7832,7 +8168,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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 @@ -7840,14 +8176,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A preprocessing directive of the form
- # undef identifier new-line+ # 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.
EXAMPLE 1 The simplest use of this facility is to define a ''manifest constant'', as in
#define TABSIZE 100
- int table[TABSIZE];
+ int table[TABSIZE];
+
EXAMPLE 2 The following defines a function-like macro whose value is the maximum of its arguments. @@ -7856,7 +8194,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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))+ #define max(a, b) ((a) > (b) ? (a) : (b)) + The parentheses ensure that the arguments and the resulting expression are bound properly.
@@ -7880,13 +8219,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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() }; + 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", "" };
+ char c[2][6] = { "hello", "" };
+
EXAMPLE 4 To illustrate the rules for creating character string literals and concatenating tokens, the @@ -7906,7 +8247,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 == 0) str(: @\n), s); #include xstr(INCFILE(2).h) glue(HIGH, LOW); - xglue(HIGH, LOW) + xglue(HIGH, LOW) + results in
@@ -7916,7 +8258,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
s);
#include "vers2.h" (after macro replacement, before file access)
"hello";
- "hello" ", world"
+ "hello" ", world"
+
or, after concatenation of the character string literals,
printf("x1= %d, x2= %s", x1, x2);
@@ -7925,7 +8268,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
s);
#include "vers2.h" (after macro replacement, before file access)
"hello";
- "hello, world"
+ "hello, world"
+
Space around the # and ## tokens in the macro definition is optional.
@@ -7933,11 +8277,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#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(,,) };
+ t(10,,), t(,11,), t(,,12), t(,,) };
+
results in
int j[] = { 123, 45, 67, 89,
- 10, 11, 12, };
+ 10, 11, 12, };
+
EXAMPLE 6 To demonstrate the redefinition rules, the following sequence is valid. @@ -7947,13 +8293,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #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
+ #define FUNC_LIKE(b) ( b ) // different parameter spelling
+
EXAMPLE 7 Finally, to show the variable argument list macro facilities: @@ -7966,17 +8314,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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); + report(x>y, "x is %d but y is %d", x, y); + 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));
+ printf("x is %d but y is %d", x, y));
+
-The string literal of a #line directive, if present, shall be a character string literal. @@ -7988,7 +8338,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A preprocessing directive of the form
- # line digit-sequence new-line+ # 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 @@ -7996,13 +8347,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A preprocessing directive of the form
- # line digit-sequence "s-char-sequenceopt" new-line+ # 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.
A preprocessing directive of the form
- # line pp-tokens new-line+ # 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 @@ -8010,21 +8363,23 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 previous forms and is then processed as appropriate. -
A preprocessing directive of the form
- # error pp-tokensopt new-line+ # error pp-tokensopt new-line + causes the implementation to produce a diagnostic message that includes the specified sequence of preprocessing tokens. -
A preprocessing directive of the form
- # pragma pp-tokensopt new-line+ # pragma pp-tokensopt new-line + where the preprocessing token STDC does not immediately follow pragma in the directive (prior to any macro replacement)152) causes the implementation to behave in an implementation-defined manner. The behavior might cause translation to fail or cause the @@ -8040,7 +8395,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #pragma STDC FENV_ACCESS on-off-switch #pragma STDC CX_LIMITED_RANGE on-off-switch on-off-switch: one of - ON OFF DEFAULT + 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). @@ -8059,65 +8415,61 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
153) See ''future language directions'' (6.11.8).
-6.10.7 Null directive
+
A preprocessing directive of the form
- # new-line+ # new-line + has no effect. -
The following macro names154) shall be defined by the implementation: - __DATE__ The date of translation of the preprocessing translation unit: a character -
+
- source line (an integer constant).155)- __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.- __STDC_MB_MIGHT_NEQ_WC__ The integer constant 1, intended to indicate that, in -
+ shall be supplied. +
+ integer character constant. +
The following macro names are conditionally defined by the implementation: - __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 -
+
-
+ compatible complex arithmetic). +
The values of the predefined macros (except for __FILE__ and __LINE__) remain constant throughout the translation unit.
@@ -8140,12 +8492,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int that is increased with each revision of this International Standard.
-6.10.9 Pragma operator
+
A unary operator expression of the form:
- _Pragma ( string-literal )+ _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 @@ -8156,72 +8509,75 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE A directive of the form:
- #pragma listing on "..\listing.dir"+ #pragma listing on "..\listing.dir" + can also be expressed as:
- _Pragma ( "listing on \"..\\listing.dir\"" )+ _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 )
+ LISTING ( ..\listing.dir )
+
-
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
+
Declaring an identifier with internal linkage at file scope without the static storage-
class specifier is an obsolescent feature.
-6.11.3 External names
+
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
+
Lowercase letters as escape sequences are reserved for future standardization. Other
characters may be used in extensions.
-6.11.5 Storage-class specifiers
+
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
+
The use of function declarators with empty parentheses (not prototype-format parameter
type declarators) is an obsolescent feature.
-6.11.7 Function definitions
+
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
+
Pragmas whose first preprocessing token is STDC are reserved for future standardization.
-6.11.9 Predefined macro names
+
Macro names beginning with __STDC_ are reserved for future standardization.
-7. Library
+
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
@@ -8264,7 +8620,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
implementation's choice.
-7.1.2 Standard headers
+
Each library function is declared, with a type that includes a prototype, in a header,159)
whose contents are made available by the #include preprocessing directive. The
@@ -8280,7 +8636,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
<ctype.h> <limits.h> <stdbool.h> <tgmath.h>
<errno.h> <locale.h> <stddef.h> <time.h>
<fenv.h> <math.h> <stdint.h> <wchar.h>
- <float.h> <setjmp.h> <stdio.h> <wctype.h>
+ <float.h> <setjmp.h> <stdio.h> <wctype.h>
+
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.
@@ -8315,7 +8672,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
necessarily valid source file names.
-7.1.3 Reserved identifiers
+
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
@@ -8349,7 +8706,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
setjmp, and va_end.
-7.1.4 Use of library functions
+
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 @@ -8399,27 +8756,31 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stdlib.h> const char *str; /* ... */ - i = atoi(str); + i = atoi(str); +
#include <stdlib.h>
#undef atoi
const char *str;
/* ... */
- i = atoi(str);
+ i = atoi(str);
+
or
#include <stdlib.h>
const char *str;
/* ... */
- i = (atoi)(str);
+ i = (atoi)(str);
+
extern int atoi(const char *);
const char *str;
/* ... */
- i = atoi(str);
+ i = atoi(str);
+
- #define abs(x) _BUILTIN_abs(x)+ #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+ #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. @@ -8448,16 +8811,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
164) Thus, a signal handler cannot, in general, call standard library functions.
-7.2 Diagnostics
+
The header <assert.h> defines the assert macro and refers to another macro,
- NDEBUG+ 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)+ #define assert(ignore) ((void)0) + The assert macro is redefined according to the current state of NDEBUG each time that <assert.h> is included.
@@ -8465,14 +8830,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
macro definition is suppressed in order to access an actual function, the behavior is
undefined.
-7.2.1 Program diagnostics
+
#include <assert.h>
- void assert(scalar expression);
+ void assert(scalar expression);
+
The assert macro puts diagnostic tests into programs; it expands to a void expression.
@@ -8498,9 +8864,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Assertion failed: expression, function abc, file xyz, line nnn.
-7.3 Complex arithmetic
+
The header <complex.h> defines macros and declares functions that support complex arithmetic.166) Each synopsis specifies a family of functions consisting of a principal @@ -8511,26 +8877,31 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macro
- complex+ complex + expands to _Complex; the macro
- _Complex_I+ _Complex_I + expands to a constant expression of type const float _Complex, with the value of the imaginary unit.167)
The macros
- imaginary+ imaginary + and
- _Imaginary_I+ _Imaginary_I + are defined if and only if the implementation supports imaginary types;168) if defined, they expand to _Imaginary and a constant expression of type const float _Imaginary with the value of the imaginary unit.
The macro
- I+ I + expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not defined, I shall expand to _Complex_I.
@@ -8545,17 +8916,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
166) See ''future library directions'' (7.26.1). -
167) The imaginary unit is a number i such that i 2 = -1. +
167) The imaginary unit is a number i such that i2 = -1.
168) A specification for imaginary types is in informative annex G.
-7.3.2 Conventions
+
Values are interpreted as radians, not degrees. An implementation may set errno but is
not required to.
-7.3.3 Branch cuts
+
Some of the functions below have branch cuts, across which the function is
discontinuous. For implementations with a signed zero (including all IEC 60559
@@ -8574,12 +8945,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <complex.h>
- #pragma STDC CX_LIMITED_RANGE on-off-switch
+ #pragma STDC CX_LIMITED_RANGE on-off-switch
+
The usual mathematical formulas for complex multiply, divide, and absolute value are @@ -8604,22 +8976,23 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(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
- ???????????????
+ (x + iy) / (u + iv) = [(xu + yv) + i(yu - xv)]/(u2 + v2)
+ | x + iy | = (sqrt)(x2 + y2)
+
where the programmer can determine they are safe.
-
#include <complex.h>
double complex cacos(double complex z);
float complex cacosf(float complex z);
- long double complex cacosl(long double complex z);
+ long double complex cacosl(long double complex z);
+
The cacos functions compute the complex arc cosine of z, with branch cuts outside the
@@ -8630,14 +9003,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the
real axis.
-7.3.5.2 The casin functions
+
#include <complex.h>
double complex casin(double complex z);
float complex casinf(float complex z);
- long double complex casinl(long double complex z);
+ long double complex casinl(long double complex z);
+
The casin functions compute the complex arc sine of z, with branch cuts outside the
@@ -8649,14 +9023,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
along the real axis.
-7.3.5.3 The catan functions
+
#include <complex.h>
double complex catan(double complex z);
float complex catanf(float complex z);
- long double complex catanl(long double complex z);
+ long double complex catanl(long double complex z);
+
The catan functions compute the complex arc tangent of z, with branch cuts outside the
@@ -8667,14 +9042,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <complex.h>
double complex ccos(double complex z);
float complex ccosf(float complex z);
- long double complex ccosl(long double complex z);
+ long double complex ccosl(long double complex z);
+
The ccos functions compute the complex cosine of z. @@ -8682,14 +9058,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The ccos functions return the complex cosine value.
-7.3.5.5 The csin functions
+
#include <complex.h>
double complex csin(double complex z);
float complex csinf(float complex z);
- long double complex csinl(long double complex z);
+ long double complex csinl(long double complex z);
+
The csin functions compute the complex sine of z.
@@ -8698,14 +9075,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The csin functions return the complex sine value.
-7.3.5.6 The ctan functions
+
#include <complex.h>
double complex ctan(double complex z);
float complex ctanf(float complex z);
- long double complex ctanl(long double complex z);
+ long double complex ctanl(long double complex z);
+
The ctan functions compute the complex tangent of z. @@ -8713,16 +9091,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The ctan functions return the complex tangent value.
-7.3.6 Hyperbolic functions
+
#include <complex.h>
double complex cacosh(double complex z);
float complex cacoshf(float complex z);
- long double complex cacoshl(long double complex z);
+ long double complex cacoshl(long double complex z);
+
The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch
@@ -8733,14 +9112,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <complex.h>
double complex casinh(double complex z);
float complex casinhf(float complex z);
- long double complex casinhl(long double complex z);
+ long double complex casinhl(long double complex z);
+
The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts
@@ -8752,14 +9132,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <complex.h>
double complex catanh(double complex z);
float complex catanhf(float complex z);
- long double complex catanhl(long double complex z);
+ long double complex catanhl(long double complex z);
+
The catanh functions compute the complex arc hyperbolic tangent of z, with branch
@@ -8770,14 +9151,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <complex.h>
double complex ccosh(double complex z);
float complex ccoshf(float complex z);
- long double complex ccoshl(long double complex z);
+ long double complex ccoshl(long double complex z);
+
The ccosh functions compute the complex hyperbolic cosine of z. @@ -8785,7 +9167,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The ccosh functions return the complex hyperbolic cosine value.
-7.3.6.5 The csinh functions
+
@@ -8793,7 +9175,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <complex.h> double complex csinh(double complex z); float complex csinhf(float complex z); - long double complex csinhl(long double complex z); + long double complex csinhl(long double complex z); +
The csinh functions compute the complex hyperbolic sine of z. @@ -8801,14 +9184,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The csinh functions return the complex hyperbolic sine value.
-7.3.6.6 The ctanh functions
+
#include <complex.h>
double complex ctanh(double complex z);
float complex ctanhf(float complex z);
- long double complex ctanhl(long double complex z);
+ long double complex ctanhl(long double complex z);
+
The ctanh functions compute the complex hyperbolic tangent of z. @@ -8816,16 +9200,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The ctanh functions return the complex hyperbolic tangent value.
-7.3.7 Exponential and logarithmic functions
+
#include <complex.h>
double complex cexp(double complex z);
float complex cexpf(float complex z);
- long double complex cexpl(long double complex z);
+ long double complex cexpl(long double complex z);
+
The cexp functions compute the complex base-e exponential of z. @@ -8833,7 +9218,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The cexp functions return the complex base-e exponential value.
-7.3.7.2 The clog functions
+
@@ -8841,7 +9226,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <complex.h> double complex clog(double complex z); float complex clogf(float complex z); - long double complex clogl(long double complex z); + long double complex clogl(long double complex z); +
The clog functions compute the complex natural (base-e) logarithm of z, with a branch
@@ -8852,16 +9238,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the
imaginary axis.
-7.3.8 Power and absolute-value functions
+
#include <complex.h>
double cabs(double complex z);
float cabsf(float complex z);
- long double cabsl(long double complex z);
+ long double cabsl(long double complex z);
+
The cabs functions compute the complex absolute value (also called norm, modulus, or @@ -8870,7 +9257,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The cabs functions return the complex absolute value.
-7.3.8.2 The cpow functions
+
@@ -8878,7 +9265,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ long double complex y);
+
The cpow functions compute the complex power function xy , with a branch cut for the
@@ -8888,14 +9276,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The cpow functions return the complex power function value.
-7.3.8.3 The csqrt functions
+
#include <complex.h>
double complex csqrt(double complex z);
float complex csqrtf(float complex z);
- long double complex csqrtl(long double complex z);
+ long double complex csqrtl(long double complex z);
+
The csqrt functions compute the complex square root of z, with a branch cut along the
@@ -8905,16 +9294,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <complex.h>
double carg(double complex z);
float cargf(float complex z);
- long double cargl(long double complex z);
+ long double cargl(long double complex z);
+
The carg functions compute the argument (also called phase angle) of z, with a branch @@ -8923,7 +9313,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The carg functions return the value of the argument in the interval [-pi , +pi ].
-7.3.9.2 The cimag functions
+
@@ -8931,7 +9321,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <complex.h> double cimag(double complex z); float cimagf(float complex z); - long double cimagl(long double complex z); + long double cimagl(long double complex z); +
The cimag functions compute the imaginary part of z.170) @@ -8943,14 +9334,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
170) For a variable z of complex type, z == creal(z) + cimag(z)*I.
-7.3.9.3 The conj functions
+
#include <complex.h>
double complex conj(double complex z);
float complex conjf(float complex z);
- long double complex conjl(long double complex z);
+ long double complex conjl(long double complex z);
+
The conj functions compute the complex conjugate of z, by reversing the sign of its @@ -8959,14 +9351,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The conj functions return the complex conjugate value.
-7.3.9.4 The cproj functions
+
#include <complex.h>
double complex cproj(double complex z);
float complex cprojf(float complex z);
- long double complex cprojl(long double complex z);
+ long double complex cprojl(long double complex z);
+
The cproj functions compute a projection of z onto the Riemann sphere: z projects to @@ -8974,7 +9367,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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))+ INFINITY + I * copysign(0.0, cimag(z)) +
The cproj functions return the value of the projection onto the Riemann sphere.
@@ -8984,14 +9378,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.3.9.5 The creal functions
+
#include <complex.h>
double creal(double complex z);
float crealf(float complex z);
- long double creall(long double complex z);
+ long double creall(long double complex z);
+
The creal functions compute the real part of z.171) @@ -9008,7 +9403,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
171) For a variable z of complex type, z == creal(z) + cimag(z)*I.
-7.4 Character handling
+
The header <ctype.h> declares several functions useful for classifying and mapping
characters.172) In all cases the argument is an int, the value of which shall be
@@ -9032,27 +9427,29 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
values lie from 0 (NUL) through 0x1F (US), and the character 0x7F (DEL).
-7.4.1 Character classification functions
+
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
+
#include <ctype.h>
- int isalnum(int c);
+ int isalnum(int c);
+
The isalnum function tests for any character for which isalpha or isdigit is true.
-7.4.1.2 The isalpha function
+
#include <ctype.h>
- int isalpha(int c);
+ int isalpha(int c);
+
The isalpha function tests for any character for which isupper or islower is true,
@@ -9069,12 +9466,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters; all four combinations are possible.
-7.4.1.3 The isblank function
+
#include <ctype.h>
- int isblank(int c);
+ int isblank(int c);
+
The isblank function tests for any character that is a standard blank character or is one
@@ -9083,32 +9481,35 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <ctype.h>
- int iscntrl(int c);
+ int iscntrl(int c);
+
The iscntrl function tests for any control character.
-7.4.1.5 The isdigit function
+
#include <ctype.h>
- int isdigit(int c);
+ int isdigit(int c);
+
The isdigit function tests for any decimal-digit character (as defined in 5.2.1).
-7.4.1.6 The isgraph function
+
#include <ctype.h>
- int isgraph(int c);
+ int isgraph(int c);
+
@@ -9118,12 +9519,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isgraph function tests for any printing character except space (' ').
-7.4.1.7 The islower function
+
#include <ctype.h>
- int islower(int c);
+ int islower(int c);
+
The islower function tests for any character that is a lowercase letter or is one of a
@@ -9131,22 +9533,24 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <ctype.h>
- int isprint(int c);
+ int isprint(int c);
+
The isprint function tests for any printing character including space (' ').
-7.4.1.9 The ispunct function
+
#include <ctype.h>
- int ispunct(int c);
+ int ispunct(int c);
+
The ispunct function tests for any printing character that is one of a locale-specific set
@@ -9154,12 +9558,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
locale, ispunct returns true for every printing character for which neither isspace
nor isalnum is true.
-7.4.1.10 The isspace function
+
#include <ctype.h>
- int isspace(int c);
+ int isspace(int c);
+
The isspace function tests for any character that is a standard white-space character or
@@ -9169,12 +9574,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
('\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
+
#include <ctype.h>
- int isupper(int c);
+ int isupper(int c);
+
The isupper function tests for any character that is an uppercase letter or is one of a
@@ -9182,24 +9588,26 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <ctype.h>
- int isxdigit(int c);
+ int isxdigit(int c);
+
The isxdigit function tests for any hexadecimal-digit character (as defined in 6.4.4.1).
-7.4.2 Character case mapping functions
+
#include <ctype.h>
- int tolower(int c);
+ int tolower(int c);
+
The tolower function converts an uppercase letter to a corresponding lowercase letter.
@@ -9211,12 +9619,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
for any given locale); otherwise, the argument is returned unchanged.
-7.4.2.2 The toupper function
+
#include <ctype.h>
- int toupper(int c);
+ int toupper(int c);
+
The toupper function converts a lowercase letter to a corresponding uppercase letter.
@@ -9228,7 +9637,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
for any given locale); otherwise, the argument is returned unchanged.
-7.5 Errors
+
The header <errno.h> defines several macros, all relating to the reporting of error conditions. @@ -9237,11 +9646,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EDOM
EILSEQ
- ERANGE
+ 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+ errno + which expands to a modifiable lvalue175) that has type int, the value of which is set to a positive error number by several library functions. It is unspecified whether errno is a macro or an identifier declared with external linkage. If a macro definition is suppressed @@ -9273,7 +9684,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
177) See ''future library directions'' (7.26.3).
-7.6 Floating-point environment
+
The header <fenv.h> declares two types and several macros and functions to provide access to the floating-point environment. The floating-point environment refers @@ -9298,12 +9709,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The type
- fenv_t+ fenv_t + represents the entire floating-point environment.
The type
- fexcept_t+ fexcept_t + represents the floating-point status flags collectively, including any status the implementation associates with the flags. @@ -9318,7 +9731,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 FE_INEXACT FE_INVALID FE_OVERFLOW - FE_UNDERFLOW + FE_UNDERFLOW + is defined if and only if the implementation supports the floating-point exception by means of the functions in 7.6.2.181) Additional implementation-defined floating-point exceptions, with macro definitions beginning with FE_ and an uppercase letter, may also @@ -9329,7 +9743,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macro
- FE_ALL_EXCEPT+ 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.
@@ -9338,7 +9753,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 FE_DOWNWARD FE_TONEAREST FE_TOWARDZERO - FE_UPWARD + 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 @@ -9352,11 +9768,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
- FE_DFL_ENV+ FE_DFL_ENV + represents the default floating-point environment -- the one installed at program startup -
Additional implementation-defined environments, with macro definitions beginning with
@@ -9384,12 +9799,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
FLT_ROUNDS, they are not required to do so.
-7.6.1 The FENV_ACCESS pragma
+
#include <fenv.h>
- #pragma STDC FENV_ACCESS on-off-switch
+ #pragma STDC FENV_ACCESS on-off-switch
+
The FENV_ACCESS pragma provides a means to inform the implementation when a
@@ -9429,7 +9845,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
g(x + 1);
h(x + 1);
/* ... */
- }
+ }
+
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.185)
@@ -9446,7 +9863,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
''off'', just one evaluation of x + 1 would suffice.
-7.6.2 Floating-point exceptions
+
The following functions provide access to the floating-point status flags.186) The int
input argument for the functions represents a subset of floating-point exceptions, and can
@@ -9462,12 +9879,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
content of flags.
-7.6.2.1 The feclearexcept function
+
#include <fenv.h>
- int feclearexcept(int excepts);
+ int feclearexcept(int excepts);
+
The feclearexcept function attempts to clear the supported floating-point exceptions
@@ -9480,13 +9898,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.6.2.2 The fegetexceptflag function
+
#include <fenv.h>
int fegetexceptflag(fexcept_t *flagp,
- int excepts);
+ int excepts);
+
The fegetexceptflag function attempts to store an implementation-defined
@@ -9497,12 +9916,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fegetexceptflag function returns zero if the representation was successfully
stored. Otherwise, it returns a nonzero value.
-7.6.2.3 The feraiseexcept function
+
#include <fenv.h>
- int feraiseexcept(int excepts);
+ int feraiseexcept(int excepts);
+
The feraiseexcept function attempts to raise the supported floating-point exceptions
@@ -9526,13 +9946,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
in F.7.6 is in the same spirit.
-7.6.2.4 The fesetexceptflag function
+
#include <fenv.h>
int fesetexceptflag(const fexcept_t *flagp,
- int excepts);
+ int excepts);
+
The fesetexceptflag function attempts to set the floating-point status flags
@@ -9547,12 +9968,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
all the specified flags were successfully set to the appropriate state. Otherwise, it returns
a nonzero value.
-7.6.2.5 The fetestexcept function
+
#include <fenv.h>
- int fetestexcept(int excepts);
+ int fetestexcept(int excepts);
+
The fetestexcept function determines which of a specified subset of the floating- @@ -9582,24 +10004,26 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 if (set_excepts & FE_INVALID) f(); if (set_excepts & FE_OVERFLOW) g(); /* ... */ - } + } +
188) This mechanism allows testing several floating-point exceptions with just one function call.
-7.6.3 Rounding
+
The fegetround and fesetround functions provide control of rounding direction
modes.
-7.6.3.1 The fegetround function
+
#include <fenv.h>
- int fegetround(void);
+ int fegetround(void);
+
The fegetround function gets the current rounding direction.
@@ -9609,12 +10033,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <fenv.h>
- int fesetround(int round);
+ int fesetround(int round);
+
The fesetround function establishes the rounding direction represented by its
@@ -9642,20 +10067,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
/* ... */
fesetround(save_round);
/* ... */
- }
+ }
+
-7.6.4 Environment
+
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
+
#include <fenv.h>
- int fegetenv(fenv_t *envp);
+ int fegetenv(fenv_t *envp);
+
The fegetenv function attempts to store the current floating-point environment in the
@@ -9665,12 +10092,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fegetenv function returns zero if the environment was successfully stored.
Otherwise, it returns a nonzero value.
-7.6.4.2 The feholdexcept function
+
#include <fenv.h>
- int feholdexcept(fenv_t *envp);
+ int feholdexcept(fenv_t *envp);
+
The feholdexcept function saves the current floating-point environment in the object
@@ -9690,12 +10118,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
function to write routines that hide spurious floating-point exceptions from their callers.
-7.6.4.3 The fesetenv function
+
#include <fenv.h>
- int fesetenv(const fenv_t *envp);
+ int fesetenv(const fenv_t *envp);
+
The fesetenv function attempts to establish the floating-point environment represented
@@ -9708,12 +10137,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fesetenv function returns zero if the environment was successfully established.
Otherwise, it returns a nonzero value.
-7.6.4.4 The feupdateenv function
+
#include <fenv.h>
- int feupdateenv(const fenv_t *envp);
+ int feupdateenv(const fenv_t *envp);
+
The feupdateenv function attempts to save the currently raised floating-point
@@ -9749,9 +10179,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
if (feupdateenv(&save_env))
return /* indication of an environmental problem */;
return result;
- }
+ }
+
-7.7 Characteristics of floating types
+
The header <float.h> defines several macros that expand to various limits and
parameters of the standard floating-point types.
@@ -9760,7 +10191,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
in 5.2.4.2.2.
-7.8 Format conversion of integer types
+
The header <inttypes.h> includes the header <stdint.h> and extends it with additional facilities provided by hosted implementations. @@ -9768,7 +10199,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 It declares functions for manipulating greatest-width integers and converting numeric character strings to greatest-width integers, and it declares the type
- imaxdiv_t+ 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.190) @@ -9779,7 +10211,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
190) See ''future library directions'' (7.26.4).
-7.8.1 Macros for format specifiers
+
Each of the following object-like macros191) expands to a character string literal containing a conversion specifier, possibly modified by a length modifier, suitable for use @@ -9794,7 +10226,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The fprintf macros for signed integers are:
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
- PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR
+ PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR
+
@@ -9807,18 +10240,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR
- PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR
+ PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR
+
The fscanf macros for signed integers are:
SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR
- SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR
+ SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR
+
The fscanf macros for unsigned integers are:
SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR
SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR
- SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR
+ SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR
+
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
@@ -9834,7 +10270,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
wprintf(L"The largest integer value is %020"
PRIxMAX "\n", i);
return 0;
- }
+ }
+
#include <inttypes.h>
- intmax_t imaxabs(intmax_t j);
+ intmax_t imaxabs(intmax_t j);
+
The imaxabs function computes the absolute value of an integer j. If the result cannot @@ -9870,12 +10308,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
193) The absolute value of the most negative number cannot be represented in two's complement.
-7.8.2.2 The imaxdiv function
+
#include <inttypes.h>
- imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
+ imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
+
The imaxdiv function computes numer / denom and numer % denom in a single
@@ -9887,7 +10326,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
@@ -9895,7 +10334,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
intmax_t strtoimax(const char * restrict nptr,
char ** restrict endptr, int base);
uintmax_t strtoumax(const char * restrict nptr,
- char ** restrict endptr, int base);
+ char ** restrict endptr, int base);
+
The strtoimax and strtoumax functions are equivalent to the strtol, strtoll,
@@ -9912,7 +10352,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(7.20.1.4).
-7.8.2.4 The wcstoimax and wcstoumax functions
+
@@ -9921,7 +10361,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ wchar_t ** restrict endptr, int base);
+
The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll,
@@ -9938,7 +10379,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(7.24.4.1.2).
-7.9 Alternative spellings
+
The header <iso646.h> defines the following eleven macros (on the left) that expand
to the corresponding tokens (on the right):
@@ -9954,9 +10395,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
or ||
or_eq |=
xor ^
- xor_eq ^=
+ xor_eq ^=
+
-7.10 Sizes of integer types
+
The header <limits.h> defines several macros that expand to various limits and
parameters of the standard integer types.
@@ -9965,13 +10407,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
in 5.2.4.2.1.
-7.11 Localization
+
The header <locale.h> declares two functions, one type, and defines several macros.
The type is
- struct lconv+ 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 @@ -10002,7 +10445,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 + char int_n_sign_posn; // CHAR_MAX + The macros defined are NULL (described in 7.17); and
LC_ALL
@@ -10010,7 +10454,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
LC_CTYPE
LC_MONETARY
LC_NUMERIC
- LC_TIME
+ LC_TIME
+
which expand to integer constant expressions with distinct values, suitable for use as the
first argument to the setlocale function.194) Additional macro definitions, beginning
with the characters LC_ and an uppercase letter,195) may also be specified by the
@@ -10022,14 +10467,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
195) See ''future library directions'' (7.26.5).
-7.11.1 Locale control
+
#include <locale.h>
- char *setlocale(int category, const char *locale);
+ char *setlocale(int category, const char *locale);
+
The setlocale function selects the appropriate portion of the program's locale as @@ -10053,7 +10499,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
At program startup, the equivalent of
- setlocale(LC_ALL, "C");+ setlocale(LC_ALL, "C"); + is executed.
The implementation shall behave as if no library function calls the setlocale function.
@@ -10085,14 +10532,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
locale when category has the value LC_ALL.
-7.11.2 Numeric formatting convention inquiry
+
#include <locale.h>
- struct lconv *localeconv(void);
+ struct lconv *localeconv(void);
+
The localeconv function sets the components of an object with type struct lconv @@ -10107,140 +10555,144 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 -
+
+ character in formatted nonmonetary quantities. +
- The decimal-point used to format monetary quantities.- char *mon_thousands_sep -
+ formatted nonmonetary quantities. +
+ monetary quantities. +
+ formatted monetary quantities. +
- 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 -
+ quantity. +
+ displayed in a locally formatted monetary quantity. +
+
+ succeeds the value for a negative locally formatted monetary quantity. +
+ quantity. +
+ quantity. +
+ nonnegative locally formatted monetary quantity. +
+ negative locally formatted monetary quantity. +
+ the international currency symbol from the monetary quantity. +
+ displayed in an internationally formatted monetary quantity. +
+ quantity. +
+
+ monetary quantity. +
+ quantity. +
-
+ nonnegative internationally formatted monetary quantity. +
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 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.+
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. +
The implementation shall behave as if no library function calls the localeconv @@ -10256,19 +10708,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 EXAMPLE 1 The following table illustrates rules which may well be used by four countries to format monetary quantities.
- Local format International format+ Local format International format - Country Positive Negative Positive Negative + 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 + 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 +
For these four countries, the respective values for the monetary members of the structure returned by localeconv could be:
- Country1 Country2 Country3 Country4+ Country1 Country2 Country3 Country4 mon_decimal_point "," "" "," "." mon_thousands_sep "." "." "." "," @@ -10291,31 +10744,30 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
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+ p_sep_by_space + p_cs_precedes p_sign_posn 0 1 2 -
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 @@ -10327,7 +10779,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The types
float_t
- double_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
@@ -10337,17 +10790,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macro
- HUGE_VAL+ HUGE_VAL + expands to a positive double constant expression, not necessarily representable as a float. The macros
HUGE_VALF
- HUGE_VALL
+ HUGE_VALL
+
are respectively float and long double analogs of HUGE_VAL.200)
The macro
- INFINITY+ 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 @@ -10358,7 +10814,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macro
- NAN+ 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.
@@ -10368,7 +10825,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 FP_NAN FP_NORMAL FP_SUBNORMAL - FP_ZERO + 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, @@ -10376,20 +10834,23 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macro
- FP_FAST_FMA+ 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.202) The macros
FP_FAST_FMAF
- FP_FAST_FMAL
+ FP_FAST_FMAL
+
are, respectively, float and long double analogs of FP_FAST_FMA. If defined,
these macros expand to the integer constant 1.
The macros
FP_ILOGB0
- FP_ILOGBNAN
+ 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.
@@ -10400,10 +10861,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macros
MATH_ERRNO
- MATH_ERREXCEPT
+ MATH_ERREXCEPT
+
expand to the integer constants 1 and 2, respectively; the macro
- math_errhandling+ 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 @@ -10432,7 +10895,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 substantially slower. -
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
@@ -10484,12 +10947,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
also ''flush-to-zero'' underflow.
-7.12.2 The FP_CONTRACT pragma
+
#include <math.h>
- #pragma STDC FP_CONTRACT on-off-switch
+ #pragma STDC FP_CONTRACT on-off-switch
+
The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the
@@ -10510,17 +10974,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.12.3 Classification macros
+
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
+
#include <math.h>
- int fpclassify(real-floating x);
+ int fpclassify(real-floating x);
+
The fpclassify macro classifies its argument value as NaN, infinite, normal, @@ -10537,7 +11002,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #define fpclassify(x) \ ((sizeof (x) == sizeof (float)) ? __fpclassifyf(x) : \ (sizeof (x) == sizeof (double)) ? __fpclassifyd(x) : \ - __fpclassifyl(x)) + __fpclassifyl(x)) +
#include <math.h>
- int isfinite(real-floating x);
+ int isfinite(real-floating x);
+
The isfinite macro determines whether its argument has a finite value (zero,
@@ -10568,12 +11035,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isfinite macro returns a nonzero value if and only if its argument has a finite
value.
-7.12.3.3 The isinf macro
+
#include <math.h>
- int isinf(real-floating x);
+ int isinf(real-floating x);
+
The isinf macro determines whether its argument value is an infinity (positive or
@@ -10584,12 +11052,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isinf macro returns a nonzero value if and only if its argument has an infinite
value.
-7.12.3.4 The isnan macro
+
#include <math.h>
- int isnan(real-floating x);
+ int isnan(real-floating x);
+
The isnan macro determines whether its argument value is a NaN. First, an argument
@@ -10604,12 +11073,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NaNs in the evaluation type but not in the semantic type.
-7.12.3.5 The isnormal macro
+
#include <math.h>
- int isnormal(real-floating x);
+ int isnormal(real-floating x);
+
@@ -10626,12 +11096,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isnormal macro returns a nonzero value if and only if its argument has a normal
value.
-
#include <math.h>
- int signbit(real-floating x);
+ int signbit(real-floating x);
+
The signbit macro determines whether the sign of its argument value is negative.207)
@@ -10645,16 +11116,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
unsigned, it is treated as positive.
-7.12.4 Trigonometric functions
+
#include <math.h>
double acos(double x);
float acosf(float x);
- long double acosl(long double x);
+ long double acosl(long double x);
+
The acos functions compute the principal value of the arc cosine of x. A domain error
@@ -10668,14 +11140,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.12.4.2 The asin functions
+
#include <math.h>
double asin(double x);
float asinf(float x);
- long double asinl(long double x);
+ long double asinl(long double x);
+
The asin functions compute the principal value of the arc sine of x. A domain error @@ -10684,14 +11157,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
-7.12.4.3 The atan functions
+
#include <math.h>
double atan(double x);
float atanf(float x);
- long double atanl(long double x);
+ long double atanl(long double x);
+
The atan functions compute the principal value of the arc tangent of x. @@ -10699,14 +11173,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
-7.12.4.4 The atan2 functions
+
#include <math.h>
double atan2(double y, double x);
float atan2f(float y, float x);
- long double atan2l(long double y, long double x);
+ long double atan2l(long double y, long double x);
+
The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
@@ -10717,14 +11192,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
-7.12.4.5 The cos functions
+
#include <math.h>
double cos(double x);
float cosf(float x);
- long double cosl(long double x);
+ long double cosl(long double x);
+
The cos functions compute the cosine of x (measured in radians). @@ -10732,14 +11208,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The cos functions return cos x.
-7.12.4.6 The sin functions
+
#include <math.h>
double sin(double x);
float sinf(float x);
- long double sinl(long double x);
+ long double sinl(long double x);
+
The sin functions compute the sine of x (measured in radians). @@ -10747,14 +11224,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The sin functions return sin x.
-7.12.4.7 The tan functions
+
#include <math.h>
double tan(double x);
float tanf(float x);
- long double tanl(long double x);
+ long double tanl(long double x);
+
The tan functions return the tangent of x (measured in radians).
@@ -10763,16 +11241,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The tan functions return tan x.
-7.12.5 Hyperbolic functions
+
#include <math.h>
double acosh(double x);
float acoshf(float x);
- long double acoshl(long double x);
+ long double acoshl(long double x);
+
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain @@ -10781,14 +11260,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The acosh functions return arcosh x in the interval [0, +(inf)].
-7.12.5.2 The asinh functions
+
#include <math.h>
double asinh(double x);
float asinhf(float x);
- long double asinhl(long double x);
+ long double asinhl(long double x);
+
The asinh functions compute the arc hyperbolic sine of x. @@ -10796,14 +11276,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The asinh functions return arsinh x.
-7.12.5.3 The atanh functions
+
#include <math.h>
double atanh(double x);
float atanhf(float x);
- long double atanhl(long double x);
+ long double atanhl(long double x);
+
The atanh functions compute the arc hyperbolic tangent of x. A domain error occurs @@ -10814,14 +11295,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The atanh functions return artanh x.
-7.12.5.4 The cosh functions
+
#include <math.h>
double cosh(double x);
float coshf(float x);
- long double coshl(long double x);
+ long double coshl(long double x);
+
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the @@ -10830,14 +11312,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The cosh functions return cosh x.
-7.12.5.5 The sinh functions
+
#include <math.h>
double sinh(double x);
float sinhf(float x);
- long double sinhl(long double x);
+ long double sinhl(long double x);
+
The sinh functions compute the hyperbolic sine of x. A range error occurs if the @@ -10846,14 +11329,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The sinh functions return sinh x.
-7.12.5.6 The tanh functions
+
#include <math.h>
double tanh(double x);
float tanhf(float x);
- long double tanhl(long double x);
+ long double tanhl(long double x);
+
The tanh functions compute the hyperbolic tangent of x. @@ -10862,41 +11346,43 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The tanh functions return tanh x.
-7.12.6 Exponential and logarithmic functions
+
#include <math.h>
double exp(double x);
float expf(float x);
- long double expl(long double x);
+ long double expl(long double x);
+
The exp functions compute the base-e exponential of x. A range error occurs if the magnitude of x is too large.
- The exp functions return ex .
+ The exp functions return ex.
-7.12.6.2 The exp2 functions
+
#include <math.h>
double exp2(double x);
float exp2f(float x);
- long double exp2l(long double x);
+ long double exp2l(long double x);
+
The exp2 functions compute the base-2 exponential of x. A range error occurs if the magnitude of x is too large.
- The exp2 functions return 2x .
+ The exp2 functions return 2x.
-7.12.6.3 The expm1 functions
+
@@ -10904,27 +11390,29 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <math.h> double expm1(double x); float expm1f(float x); - long double expm1l(long double x); + long double expm1l(long double x); +
The expm1 functions compute the base-e exponential of the argument, minus 1. A range error occurs if x is too large.208)
- The expm1 functions return ex - 1. + The expm1 functions return ex - 1.
208) For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
-7.12.6.4 The frexp functions
+
#include <math.h>
double frexp(double value, int *exp);
float frexpf(float value, int *exp);
- long double frexpl(long double value, int *exp);
+ long double frexpl(long double value, int *exp);
+
The frexp functions break a floating-point number into a normalized fraction and an @@ -10933,16 +11421,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
If value is not a floating-point number, 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.
+ zero, and value equals x 2*exp . If value is zero, both parts of the result are zero.
-7.12.6.5 The ilogb functions
+
#include <math.h>
int ilogb(double x);
int ilogbf(float x);
- int ilogbl(long double x);
+ int ilogbl(long double x);
+
The ilogb functions extract the exponent of x as a signed int value. If x is zero they @@ -10961,30 +11450,32 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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
+
#include <math.h>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
- long double ldexpl(long double x, int exp);
+ long double ldexpl(long double x, int exp);
+
The ldexp functions multiply a floating-point number by an integral power of 2. A range error may occur.
- The ldexp functions return x x 2exp .
+ The ldexp functions return x 2exp .
-7.12.6.7 The log functions
+
#include <math.h>
double log(double x);
float logf(float x);
- long double logl(long double x);
+ long double logl(long double x);
+
The log functions compute the base-e (natural) logarithm of x. A domain error occurs if @@ -10993,7 +11484,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The log functions return loge x.
-7.12.6.8 The log10 functions
+
@@ -11001,7 +11492,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <math.h> double log10(double x); float log10f(float x); - long double log10l(long double x); + long double log10l(long double x); +
The log10 functions compute the base-10 (common) logarithm of x. A domain error @@ -11010,14 +11502,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The log10 functions return log10 x.
-7.12.6.9 The log1p functions
+
#include <math.h>
double log1p(double x);
float log1pf(float x);
- long double log1pl(long double x);
+ long double log1pl(long double x);
+
The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.209) @@ -11031,14 +11524,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
209) For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
-7.12.6.10 The log2 functions
+
#include <math.h>
double log2(double x);
float log2f(float x);
- long double log2l(long double x);
+ long double log2l(long double x);
+
The log2 functions compute the base-2 logarithm of x. A domain error occurs if the
@@ -11052,34 +11546,37 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.12.6.11 The logb functions
+
#include <math.h>
double logb(double x);
float logbf(float x);
- long double logbl(long double x);
+ long double logbl(long double x);
+
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+ 1 <= x FLT_RADIX-logb(x) < FLT_RADIX + A domain error or range error may occur if the argument is zero.
The logb functions return the signed exponent of x.
-7.12.6.12 The modf functions
+
#include <math.h>
double modf(double value, double *iptr);
float modff(float value, float *iptr);
- long double modfl(long double value, long double *iptr);
+ long double modfl(long double value, long double *iptr);
+
The modf functions break the argument value into integral and fractional parts, each of
@@ -11090,7 +11587,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The modf functions return the signed fractional part of value.
-7.12.6.13 The scalbn and scalbln functions
+
@@ -11100,40 +11597,43 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ long double scalblnl(long double x, long int n);
+
- The scalbn and scalbln functions compute x x FLT_RADIXn efficiently, not - normally by computing FLT_RADIXn explicitly. A range error may occur. + The scalbn and scalbln functions compute x FLT_RADIXn efficiently, not + normally by computing FLT_RADIXn explicitly. A range error may occur.
- The scalbn and scalbln functions return x x FLT_RADIXn .
+ The scalbn and scalbln functions return x FLT_RADIXn .
-7.12.7 Power and absolute-value functions
+
#include <math.h>
double cbrt(double x);
float cbrtf(float x);
- long double cbrtl(long double x);
+ long double cbrtl(long double x);
+
The cbrt functions compute the real cube root of x.
- The cbrt functions return x1/3 .
+ The cbrt functions return x1/3.
-7.12.7.2 The fabs functions
+
#include <math.h>
double fabs(double x);
float fabsf(float x);
- long double fabsl(long double x);
+ long double fabsl(long double x);
+
The fabs functions compute the absolute value of a floating-point number x. @@ -11142,14 +11642,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fabs functions return | x |.
-7.12.7.3 The hypot functions
+
#include <math.h>
double hypot(double x, double y);
float hypotf(float x, float y);
- long double hypotl(long double x, long double y);
+ long double hypotl(long double x, long double y);
+
The hypot functions compute the square root of the sum of the squares of x and y, @@ -11157,19 +11658,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
- The hypot functions return (sqrt)x2 + y2 . -
- ??? - ???????????????+ The hypot functions return (sqrt)(x2 + y2). -
#include <math.h>
double pow(double x, double y);
float powf(float x, float y);
- long double powl(long double x, long double y);
+ long double powl(long double x, long double y);
+
The pow functions compute x raised to the power y. A domain error occurs if x is finite @@ -11178,9 +11677,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 is zero and y is less than zero.
- The pow functions return xy .
+ The pow functions return xy.
-7.12.7.5 The sqrt functions
+
@@ -11188,83 +11687,71 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <math.h> double sqrt(double x); float sqrtf(float x); - long double sqrtl(long double x); + long double sqrtl(long double x); +
The sqrt functions compute the nonnegative square root of x. A domain error occurs if the argument is less than zero.
- The sqrt functions return (sqrt)x. -
- ??? - ???+ The sqrt functions return (sqrt)(x). -
#include <math.h>
double erf(double x);
float erff(float x);
- long double erfl(long double x);
+ long double erfl(long double x);
+
The erf functions compute the error function of x.
+ The erf functions return
- 2 x - (integral)- - The erf functions return erf x = e-t dt. -
- 2- - -
- (sqrt)pi - ??? - ??? 0- + 2 x + erf x = --- (integral) e-t2 dt . + (sqrt)(pi) 0 + -
#include <math.h>
double erfc(double x);
float erfcf(float x);
- long double erfcl(long double x);
+ long double erfcl(long double x);
+
The erfc functions compute the complementary error function of x. A range error occurs if x is too large.
+ The erfc functions return
- 2 (inf) - (integral)- - The erfc functions return erfc x = 1 - erf x = e-t dt. -
- 2- + 2 (inf) + erfc x = 1 - erf x = --- (integral) e-t2 dt . + (sqrt)(pi) x + -
- (sqrt)pi - ??? - ??? x- -
#include <math.h>
double lgamma(double x);
float lgammaf(float x);
- long double lgammal(long double x);
+ long double lgammal(long double x);
+
The lgamma functions compute the natural logarithm of the absolute value of gamma of @@ -11274,14 +11761,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The lgamma functions return loge | (Gamma)(x) |.
-7.12.8.4 The tgamma functions
+
#include <math.h>
double tgamma(double x);
float tgammaf(float x);
- long double tgammal(long double x);
+ long double tgammal(long double x);
+
The tgamma functions compute the gamma function of x. A domain error or range error @@ -11291,47 +11779,50 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The tgamma functions return (Gamma)(x).
-7.12.9 Nearest integer functions
+
#include <math.h>
double ceil(double x);
float ceilf(float x);
- long double ceill(long double x);
+ long double ceill(long double x);
+
The ceil functions compute the smallest integer value not less than x.
- The ceil functions return ???x???, expressed as a floating-point number.
+ The ceil functions return [^x^], expressed as a floating-point number.
-7.12.9.2 The floor functions
+
#include <math.h>
double floor(double x);
float floorf(float x);
- long double floorl(long double x);
+ long double floorl(long double x);
+
The floor functions compute the largest integer value not greater than x.
- The floor functions return ???x???, expressed as a floating-point number.
+ The floor functions return [_x_], expressed as a floating-point number.
-7.12.9.3 The nearbyint functions
+
#include <math.h>
double nearbyint(double x);
float nearbyintf(float x);
- long double nearbyintl(long double x);
+ long double nearbyintl(long double x);
+
The nearbyint functions round their argument to an integer value in floating-point @@ -11341,14 +11832,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The nearbyint functions return the rounded integer value.
-7.12.9.4 The rint functions
+
#include <math.h>
double rint(double x);
float rintf(float x);
- long double rintl(long double x);
+ long double rintl(long double x);
+
The rint functions differ from the nearbyint functions (7.12.9.3) only in that the @@ -11359,7 +11851,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The rint functions return the rounded integer value.
-7.12.9.5 The lrint and llrint functions
+
@@ -11369,7 +11861,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ long long int llrintl(long double x);
+
The lrint and llrint functions round their argument to the nearest integer value, @@ -11380,14 +11873,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The lrint and llrint functions return the rounded integer value.
-7.12.9.6 The round functions
+
#include <math.h>
double round(double x);
float roundf(float x);
- long double roundl(long double x);
+ long double roundl(long double x);
+
The round functions round their argument to the nearest integer value in floating-point
@@ -11398,7 +11892,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The round functions return the rounded integer value.
-7.12.9.7 The lround and llround functions
+
@@ -11408,7 +11902,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ long long int llroundl(long double x);
+
The lround and llround functions round their argument to the nearest integer value, @@ -11419,14 +11914,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The lround and llround functions return the rounded integer value.
-7.12.9.8 The trunc functions
+
#include <math.h>
double trunc(double x);
float truncf(float x);
- long double truncl(long double x);
+ long double truncl(long double x);
+
The trunc functions round their argument to the integer value, in floating format,
@@ -11436,16 +11932,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The trunc functions return the truncated integer value.
-7.12.10 Remainder functions
+
#include <math.h>
double fmod(double x, double y);
float fmodf(float x, float y);
- long double fmodl(long double x, long double y);
+ long double fmodl(long double x, long double y);
+
The fmod functions compute the floating-point remainder of x/y.
@@ -11456,14 +11953,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
whether a domain error occurs or the fmod functions return zero is implementation-
defined.
-7.12.10.2 The remainder functions
+
#include <math.h>
double remainder(double x, double y);
float remainderf(float x, float y);
- long double remainderl(long double x, long double y);
+ long double remainderl(long double x, long double y);
+
The remainder functions compute the remainder x REM y required by IEC 60559.210)
@@ -11484,7 +11982,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
x.'' This definition is applicable for all implementations.
-7.12.10.3 The remquo functions
+
@@ -11492,12 +11990,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ int *quo);
+
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 + 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.
@@ -11505,16 +12004,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
#include <math.h>
double copysign(double x, double y);
float copysignf(float x, float y);
- long double copysignl(long double x, long double y);
+ long double copysignl(long double x, long double y);
+
The copysign functions produce a value with the magnitude of x and the sign of y.
@@ -11526,14 +12026,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The copysign functions return a value with the magnitude of x and the sign of y.
-7.12.11.2 The nan functions
+
#include <math.h>
double nan(const char *tagp);
float nanf(const char *tagp);
- long double nanl(const char *tagp);
+ long double nanl(const char *tagp);
+
The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char- @@ -11548,14 +12049,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 If the implementation does not support quiet NaNs, the functions return zero.
Forward references: the strtod, strtof, and strtold functions (7.20.1.3).
-7.12.11.3 The nextafter functions
+
#include <math.h>
double nextafter(double x, double y);
float nextafterf(float x, float y);
- long double nextafterl(long double x, long double y);
+ long double nextafterl(long double x, long double y);
+
The nextafter functions determine the next representable value, in the type of the
@@ -11576,14 +12078,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
function.
-7.12.11.4 The nexttoward functions
+
#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);
+ long double nexttowardl(long double x, long double y);
+
The nexttoward functions are equivalent to the nextafter functions except that the
@@ -11595,36 +12098,39 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
range or precision in a floating second argument.
-7.12.12 Maximum, minimum, and positive difference functions
+
#include <math.h>
double fdim(double x, double y);
float fdimf(float x, float y);
- long double fdiml(long double x, long double y);
+ long double fdiml(long double x, long double y);
+
The fdim functions determine the positive difference between their arguments:
- ???x - y if x > y - ??? - ???+0 if x <= y+ {x - y if x > y + { + {+0 if x <= y + A range error may occur.
The fdim functions return the positive difference value.
-7.12.12.2 The fmax functions
+
#include <math.h>
double fmax(double x, double y);
float fmaxf(float x, float y);
- long double fmaxl(long double x, long double y);
+ long double fmaxl(long double x, long double y);
+
@@ -11641,14 +12147,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
fmax functions choose the numeric value. See F.9.9.2.
-
#include <math.h>
double fmin(double x, double y);
float fminf(float x, float y);
- long double fminl(long double x, long double y);
+ long double fminl(long double x, long double y);
+
The fmin functions determine the minimum numeric value of their arguments.214) @@ -11660,9 +12167,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
214) The fmin functions are analogous to the fmax functions in their treatment of NaNs.
-7.12.13 Floating multiply-add
+
@@ -11670,22 +12177,23 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ long double z);
+
- The fma functions compute (x x y) + z, rounded as one ternary operation: they compute + The fma functions compute (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.
- The fma functions return (x x y) + z, rounded as one ternary operation.
+ The fma functions return (x y) + z, rounded as one ternary operation.
-7.12.14 Comparison macros
+
The relational and equality operators support the usual mathematical relationships
between numeric values. For any ordered pair of numeric values exactly one of the
@@ -11704,12 +12212,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NaNs; the result in these cases is false.
-7.12.14.1 The isgreater macro
+
#include <math.h>
- int isgreater(real-floating x, real-floating y);
+ int isgreater(real-floating x, real-floating y);
+
The isgreater macro determines whether its first argument is greater than its second @@ -11720,12 +12229,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isgreater macro returns the value of (x) > (y).
-7.12.14.2 The isgreaterequal macro
+
#include <math.h>
- int isgreaterequal(real-floating x, real-floating y);
+ int isgreaterequal(real-floating x, real-floating y);
+
The isgreaterequal macro determines whether its first argument is greater than or @@ -11740,12 +12250,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isgreaterequal macro returns the value of (x) >= (y).
-7.12.14.3 The isless macro
+
#include <math.h>
- int isless(real-floating x, real-floating y);
+ int isless(real-floating x, real-floating y);
+
The isless macro determines whether its first argument is less than its second @@ -11756,12 +12267,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isless macro returns the value of (x) < (y).
-7.12.14.4 The islessequal macro
+
#include <math.h>
- int islessequal(real-floating x, real-floating y);
+ int islessequal(real-floating x, real-floating y);
+
The islessequal macro determines whether its first argument is less than or equal to @@ -11772,12 +12284,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The islessequal macro returns the value of (x) <= (y).
-7.12.14.5 The islessgreater macro
+
#include <math.h>
- int islessgreater(real-floating x, real-floating y);
+ int islessgreater(real-floating x, real-floating y);
+
The islessgreater macro determines whether its first argument is less than or @@ -11790,12 +12303,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The islessgreater macro returns the value of (x) < (y) || (x) > (y).
-7.12.14.6 The isunordered macro
+
#include <math.h>
- int isunordered(real-floating x, real-floating y);
+ int isunordered(real-floating x, real-floating y);
+
The isunordered macro determines whether its arguments are unordered.
@@ -11804,14 +12318,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The isunordered macro returns 1 if its arguments are unordered and 0 otherwise.
-7.13 Nonlocal jumps
+
The header <setjmp.h> defines the macro setjmp, and declares one function and one type, for bypassing the normal function call and return discipline.216)
The type declared is
- jmp_buf+ 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 @@ -11828,14 +12343,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 a program. -
#include <setjmp.h>
- int setjmp(jmp_buf env);
+ int setjmp(jmp_buf env);
+
The setjmp macro saves its calling environment in its jmp_buf argument for later use @@ -11845,7 +12361,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
An invocation of the setjmp macro shall appear only in one of the following contexts:
If the invocation appears in any other context, the behavior is undefined.
-7.13.2 Restore calling environment
+
#include <setjmp.h>
- void longjmp(jmp_buf env, int val);
+ void longjmp(jmp_buf env, int val);
+
The longjmp function restores the environment saved by the most recent invocation of @@ -11922,7 +12439,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 { int b[n]; // b may remain allocated longjmp(buf, 2); // might cause memory loss - } + } +
217) For example, by executing a return statement or because another longjmp call has caused a @@ -11931,14 +12449,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
218) This includes, but is not limited to, the floating-point status flags and the state of open files.
-7.14 Signal handling
+
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).
The type defined is
- sig_atomic_t+ 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.
@@ -11946,7 +12465,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
SIG_DFL
SIG_ERR
- SIG_IGN
+ 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
@@ -11960,7 +12480,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+ SIGTERM a termination request sent to the program
+
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
@@ -11979,14 +12500,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
and termination.
-
#include <signal.h>
- void (*signal(int sig, void (*func)(int)))(int);
+ void (*signal(int sig, void (*func)(int)))(int);
+
The signal function chooses one of three ways in which receipt of the signal number @@ -12021,14 +12543,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
At program startup, the equivalent of
- signal(sig, SIG_IGN);+ signal(sig, SIG_IGN); + may be executed for some signals selected in an implementation-defined manner; the equivalent of
- signal(sig, SIG_DFL);+ signal(sig, SIG_DFL); + is executed for all other signals defined by the implementation.
The implementation shall behave as if no library function calls the signal function. @@ -12044,14 +12568,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
220) If any signal is generated by an asynchronous signal handler, the behavior is undefined.
-7.14.2 Send signal
+
#include <signal.h>
- int raise(int sig);
+ int raise(int sig);
+
The raise function carries out the actions described in 7.14.1.1 for the signal sig. If a
@@ -12062,7 +12587,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The raise function returns zero if successful, nonzero if unsuccessful.
-7.15 Variable arguments
+
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 @@ -12075,7 +12600,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The type declared is
- va_list+ va_list + which is an 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 @@ -12089,7 +12615,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 case the original function may make further use of the original list after the other function returns. -
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
@@ -12099,12 +12625,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
shall be matched by a corresponding invocation of the va_end macro in the same
function.
-7.15.1.1 The va_arg macro
+
#include <stdarg.h>
- type va_arg(va_list ap, type);
+ type va_arg(va_list ap, type);
+
The va_arg macro expands to an expression that has the specified type and the value of
@@ -12130,12 +12657,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
value of the argument after that specified by parmN . Successive invocations return the
values of the remaining arguments in succession.
-7.15.1.2 The va_copy macro
+
#include <stdarg.h>
- void va_copy(va_list dest, va_list src);
+ void va_copy(va_list dest, va_list src);
+
The va_copy macro initializes dest as a copy of src, as if the va_start macro had @@ -12147,12 +12675,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The va_copy macro returns no value.
-7.15.1.3 The va_end macro
+
#include <stdarg.h>
- void va_end(va_list ap);
+ void va_end(va_list ap);
+
The va_end macro facilitates a normal return from the function whose variable @@ -12167,12 +12696,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The va_end macro returns no value.
-7.15.1.4 The va_start macro
+
#include <stdarg.h>
- void va_start(va_list ap, parmN);
+ void va_start(va_list ap, parmN);
+
The va_start macro shall be invoked before any access to the unnamed arguments. @@ -12202,17 +12732,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 va_list ap; char *array[MAXARGS]; int ptr_no = 0; - 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); - } + 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, ...);+ void f1(int, ...); +
EXAMPLE 2 The function f3 is similar, but saves the status of the variable argument list after the
@@ -12244,27 +12776,32 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
array[ptr_no++] = va_arg(ap_save, char *);
va_end(ap_save);
f4(n_ptrs, array);
- }
+ }
+
-7.16 Boolean type and values
+
The header <stdbool.h> defines four macros.
The macro
- bool+ bool + expands to _Bool.
The remaining three macros are suitable for use in #if preprocessing directives. They are
- true+ true + which expands to the integer constant 1,
- false+ false + which expands to the integer constant 0, and
- __bool_true_false_are_defined+ __bool_true_false_are_defined + which expands to the integer constant 1.
Notwithstanding the provisions of 7.1.3, a program may undefine and perhaps then @@ -12279,20 +12816,23 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
222) See ''future library directions'' (7.26.7).
-7.17 Common definitions
+
The following types and macros are defined in the standard header <stddef.h>. Some are also defined in other headers, as noted in their respective subclauses.
The types are
- ptrdiff_t+ ptrdiff_t + which is the signed integer type of the result of subtracting two pointers;
- size_t+ size_t + which is the unsigned integer type of the result of the sizeof operator; and
- wchar_t+ 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 @@ -12302,19 +12842,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macros are
- NULL+ NULL + which expands to an implementation-defined null pointer constant; and
- offsetof(type, member-designator)+ 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;+ 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 +
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 @@ -12322,7 +12865,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: localization (7.11).
-7.18 Integer types
+
The header <stdint.h> declares sets of integer types having specified widths, and defines corresponding sets of macros.223) It also defines macros that specify limits of @@ -12354,7 +12897,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
224) Some of these types may denote implementation-defined extended integer types.
-7.18.1 Integer types
+
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
@@ -12368,7 +12911,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.18.1.1 Exact-width integer types
+
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 a signed integer
@@ -12381,7 +12924,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.18.1.2 Minimum-width integer types
+
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.
@@ -12397,10 +12940,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int_least8_t uint_least8_t
int_least16_t uint_least16_t
int_least32_t uint_least32_t
- int_least64_t uint_least64_t
+ int_least64_t uint_least64_t
+
All other types of this form are optional.
-7.18.1.3 Fastest minimum-width integer types
+
Each of the following types designates an integer type that is usually fastest225) to operate with among all integer types that have at least the specified width. @@ -12419,7 +12963,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 int_fast8_t uint_fast8_t int_fast16_t uint_fast16_t int_fast32_t uint_fast32_t - int_fast64_t uint_fast64_t + int_fast64_t uint_fast64_t + All other types of this form are optional.
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+ 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+ uintptr_t + These types are optional. -
The following type designates a signed integer type capable of representing any value of any signed integer type:
- intmax_t+ intmax_t + The following type designates an unsigned integer type capable of representing any value of any unsigned integer type:
- uintmax_t+ uintmax_t + These types are required. -
The following object-like macros226) specify the minimum and maximum limits of the
types declared in <stdint.h>. Each macro name corresponds to a similar type name in
@@ -12474,65 +13023,93 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
before <stdint.h> is included.
-7.18.2.1 Limits of exact-width integer types
+
+ INTN_MIN exactly -(2N-1) +
+ INTN_MAX exactly 2N-1 - 1 +
+ UINTN_MAX exactly 2N - 1 +
+ INT_LEASTN_MIN -(2N-1 - 1) +
+ INT_LEASTN_MAX 2N-1 - 1 +
+ UINT_LEASTN_MAX 2N - 1 +
+ INT_FASTN_MIN -(2N-1 - 1) +
+ INT_FASTN_MAX 2N-1 - 1 +
+ UINT_FASTN_MAX 2N - 1 +
- INTPTR_MIN -(215 - 1)+ INTPTR_MIN -(215 - 1) +
- INTPTR_MAX 215 - 1+ INTPTR_MAX 215 - 1 +
+ UINTPTR_MAX 216 - 1 +
+ INTMAX_MIN -(263 - 1) +
+ INTMAX_MAX 263 - 1 +
+ UINTMAX_MAX 264 - 1 +
The following object-like macros227) specify the minimum and maximum limits of integer types corresponding to types defined in other standard headers. @@ -12546,23 +13123,31 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 actually provides.228)
+ PTRDIFF_MIN -65535 + PTRDIFF_MAX +65535 +
+ SIG_ATOMIC_MIN see below + SIG_ATOMIC_MAX see below +
+ SIZE_MAX 65535 +
+ WCHAR_MIN see below + WCHAR_MAX see below +
+ WINT_MIN see below + WINT_MAX see below +
If sig_atomic_t (see 7.14) is defined as a signed integer type, the value of
@@ -12591,7 +13176,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character set.
-7.18.4 Macros for integer constants
+
The following function-like macros230) expand to integer constants suitable for
initializing objects that have integer types corresponding to types defined in
@@ -12616,7 +13201,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
defined before <stdint.h> is included.
-7.18.4.1 Macros for minimum-width integer constants
+
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
@@ -12624,34 +13209,38 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.18.4.2 Macros for greatest-width integer constants
+
The following macro expands to an integer constant expression having the value specified by its argument and the type intmax_t:
- INTMAX_C(value)+ 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)+ UINTMAX_C(value) + -
The header <stdio.h> declares three types, several macros, and many functions for performing input and output.
The types declared are size_t (described in 7.17);
- FILE+ 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+ fpos_t + which is an object type other than an array type capable of recording all the information needed to specify uniquely every position within a file.
@@ -12659,47 +13248,56 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
_IOFBF
_IOLBF
- _IONBF
+ _IONBF
+
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the setvbuf function;
- BUFSIZ+ BUFSIZ + which expands to an integer constant expression that is the size of the buffer used by the setbuf function;
- EOF+ 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+ 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+ 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 guarantees can be opened;231)
- L_tmpnam+ 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
+ SEEK_SET
+
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the fseek function;
- TMP_MAX+ TMP_MAX + which expands to an integer constant expression that is the maximum number of unique file names that can be generated by the tmpnam function;
stderr
stdin
- stdout
+ 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.
@@ -12738,7 +13336,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
all possible strings of length FILENAME_MAX cannot be expected to be opened successfully.
-7.19.2 Streams
+
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 @@ -12794,7 +13392,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
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 @@ -12816,7 +13414,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
233) The three predefined streams stdin, stdout, and stderr are unoriented at program startup.
-7.19.3 Files
+
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 @@ -12863,9 +13461,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
At program startup, three text streams are predefined and need not be opened explicitly -
The value of FOPEN_MAX shall be at least eight, including the three standard text
streams.
@@ -12928,14 +13524,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
with state-dependent encoding that does not assuredly end in the initial shift state.
-7.19.4 Operations on files
+
#include <stdio.h>
- int remove(const char *filename);
+ int remove(const char *filename);
+
The remove function causes the file whose name is the string pointed to by filename @@ -12946,12 +13543,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The remove function returns zero if the operation succeeds, nonzero if it fails.
-7.19.4.2 The rename function
+
#include <stdio.h>
- int rename(const char *old, const char *new);
+ int rename(const char *old, const char *new);
+
The rename function causes the file whose name is the string pointed to by old to be
@@ -12969,19 +13567,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
or that it is necessary to copy its contents to effectuate its renaming.
-7.19.4.3 The tmpfile function
+
#include <stdio.h>
- FILE *tmpfile(void);
+ FILE *tmpfile(void);
+
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 +
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 @@ -12993,12 +13592,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 cannot be created, the tmpfile function returns a null pointer.
Forward references: the fopen function (7.19.5.3).
-7.19.4.4 The tmpnam function
+
#include <stdio.h>
- char *tmpnam(char *s);
+ char *tmpnam(char *s);
+
The tmpnam function generates a string that is a valid file name and that is not the same @@ -13020,7 +13620,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
The value of the macro TMP_MAX shall be at least 25.
@@ -13031,14 +13631,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
is ended, and before program termination.
-7.19.5 File access functions
+
#include <stdio.h>
- int fclose(FILE *stream);
+ int fclose(FILE *stream);
+
A successful call to the fclose function causes the stream pointed to by stream to be
@@ -13052,13 +13653,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fclose function returns zero if the stream was successfully closed, or EOF if any
errors were detected.
-7.19.5.2 The fflush function
+
#include <stdio.h>
- int fflush(FILE *stream);
+ int fflush(FILE *stream);
+
If stream points to an output stream or an update stream in which the most recent @@ -13074,13 +13676,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 error occurs, otherwise it returns zero.
Forward references: the fopen function (7.19.5.3).
-7.19.5.3 The fopen function
+
#include <stdio.h>
FILE *fopen(const char * restrict filename,
- const char * restrict mode);
+ const char * restrict mode);
+
The fopen function opens the file whose name is the string pointed to by filename, @@ -13088,23 +13691,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.237) - r open text file for reading - w truncate to zero length or 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 - 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 - a+ append; open or create text file for update, writing at end-of-file - - - +
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.
@@ -13139,14 +13741,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
conform to the properties in 7.19.2).
-7.19.5.4 The freopen function
+
#include <stdio.h>
FILE *freopen(const char * restrict filename,
const char * restrict mode,
- FILE * restrict stream);
+ FILE * restrict stream);
+
The freopen function opens the file whose name is the string pointed to by filename
@@ -13173,13 +13776,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
returned by the fopen function may be assigned.
-7.19.5.5 The setbuf function
+
#include <stdio.h>
void setbuf(FILE * restrict stream,
- char * restrict buf);
+ char * restrict buf);
+
Except that it returns no value, the setbuf function is equivalent to the setvbuf @@ -13190,14 +13794,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The setbuf function returns no value.
Forward references: the setvbuf function (7.19.5.6).
-7.19.5.6 The setvbuf function
+
#include <stdio.h>
int setvbuf(FILE * restrict stream,
char * restrict buf,
- int mode, size_t size);
+ int mode, size_t size);
+
@@ -13225,7 +13830,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
before a buffer that has automatic storage duration is deallocated upon block exit.
-The formatted input/output functions shall behave as if there is a sequence point after the actions associated with each specifier.240) @@ -13234,13 +13839,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
240) The fprintf functions perform writes to memory for the %n specifier.
-7.19.6.1 The fprintf function
+
#include <stdio.h>
int fprintf(FILE * restrict stream,
- const char * restrict format, ...);
+ const char * restrict format, ...);
+
The fprintf function writes output to the stream pointed to by stream, under control @@ -13289,25 +13895,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 precision were omitted.
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.)242)- space If the first character of a signed conversion is not a sign, or if a signed conversion -
+ specified.)242) +
+ both appear, the space flag is ignored. +
-
+ result. For other conversions, the behavior is undefined. +
The length modifiers and their meanings are: - hh Specifies that a following d, i, o, u, x, or X conversion specifier applies to a -
+
+ argument. +
+ int argument. +
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
-+ specifier. +
+ argument. +
+ specifier applies to a pointer to an intmax_t argument. +
+ corresponding to size_t argument. +
- applies to a long double argument.- If a length modifier appears with any conversion specifier other than as specified above, + argument. +
The conversion specifiers and their meanings are: - d,i The int argument is converted to signed decimal in the style [-]dddd. The -
+
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
-+ zero value with a precision of zero is no characters. +
+ respectively.243) +
+ of an f or F conversion specifier. +
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
-+ of an f or F conversion specifier. +
+ of an f or F conversion specifier. +
- element of an array of character type.246) Characters from the array are- - + second a null wide character. +
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
@@ -13485,21 +14066,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
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.247)
- p The argument shall be a pointer to void. The value of the pointer is
-+ end of the array. In no case is a partial multibyte character written.247) +
+ manner. +
-
- conversion specification shall be %%.If a conversion specification is invalid, the behavior is undefined.248) If any argument is not the correct type for the corresponding conversion specification, the behavior is undefined. @@ -13515,7 +14094,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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 +
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 @@ -13534,7 +14113,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fprintf function returns the number of characters transmitted, or a negative value if an output or encoding error occurred. - Environmental limits +
The number of characters that can be produced by any single conversion shall be at least 4095. @@ -13549,7 +14128,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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)); + fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0)); +
EXAMPLE 2 In this example, multibyte characters do not have a state-dependent encoding, and the @@ -13563,7 +14143,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Given the following wide string with length seven,
- static wchar_t wstr[] = L" X Yabc Z W";+ static wchar_t wstr[] = L" X Yabc Z W"; + the seven calls
fprintf(stdout, "|1234567890123|\n");
@@ -13572,7 +14153,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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]);
+ fprintf(stdout, "|%13lc|\n", (wint_t) wstr[5]);
+
will print the following seven lines:
|1234567890123|
@@ -13581,7 +14163,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
| X Yabc Z|
| X Yabc Z W|
| abc Z W|
- | Z|
+ | Z|
+
Forward references: conversion state (7.24.6), the wcrtomb function (7.24.6.3.3). @@ -13597,7 +14180,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
244) 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. -
245) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is +
245) The precision p is sufficient to distinguish values of the source type if 16p-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.
@@ -13613,13 +14196,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the case of fixed-point conversion by the source value as well.
-7.19.6.2 The fscanf function
+
#include <stdio.h>
int fscanf(FILE * restrict stream,
- const char * restrict format, ...);
+ const char * restrict format, ...);
+
The fscanf function reads input from the stream pointed to by stream, under control @@ -13686,73 +14270,61 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 in the object, the behavior is undefined.
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 -
+
+ int. +
+ conversion specifier applies to an argument with type pointer to wchar_t. +
- 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 -
+ long long int. +
+ integer type. +
- applies to an argument with type pointer to long double.+ unsigned integer type. +
The conversion specifiers and their meanings are: - d Matches an optionally signed decimal integer, whose format is the same as -
+
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
-+ integer. +
+ unsigned integer. +
+ unsigned integer. +
+ unsigned integer. +
+ function. The corresponding argument shall be a pointer to floating. +
+ No null wide character is added. +
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).252) + added automatically. +
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
-+ equal to that value; otherwise the behavior of the %p conversion is undefined. +
-
- complete conversion specification shall be %%.If a conversion specification is invalid, the behavior is undefined.253)
The conversion specifiers A, E, F, G, and X are also valid and behave the same as, @@ -13849,10 +14414,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stdio.h> /* ... */ int n, i; float x; char name[50]; - n = fscanf(stdin, "%d%f%s", &i, &x, name); + n = fscanf(stdin, "%d%f%s", &i, &x, name); + with the input line:
- 25 54.32E-1 thompson+ 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. @@ -13862,14 +14429,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stdio.h> /* ... */ int i; float x; char name[50]; - fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name); + fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name); + with input:
- 56789 0123 56a72+ 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. @@ -13883,7 +14452,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 do { count = fscanf(stdin, "%f%20s of %20s", &quant, units, item); fscanf(stdin,"%*[^\n]"); - } while (!feof(stdin) && !ferror(stdin)); + } while (!feof(stdin) && !ferror(stdin)); + If the stdin stream contains the following lines:
2 quarts of oil
@@ -13891,7 +14461,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
lots of luck
10.0LBS of
dirt
- 100ergs of energy
+ 100ergs of energy
+
the execution of the above example will be analogous to the following assignments:
quant = 2; strcpy(units, "quarts"); strcpy(item, "oil");
@@ -13902,7 +14473,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
quant = 10.0; strcpy(units, "LBS"); strcpy(item, "dirt");
count = 3;
count = 0; // "100e" fails to match "%f"
- count = EOF;
+ count = EOF;
+
EXAMPLE 4 In: @@ -13910,7 +14482,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stdio.h> /* ... */ int d1, d2, n1, n2, i; - i = sscanf("123", "%d%n%n%d", &d1, &n1, &n2, &d2); + 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. @@ -13927,10 +14500,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stdio.h> /* ... */ char str[50]; - fscanf(stdin, "a%s", str); + fscanf(stdin, "a%s", str); + with the input line:
- a(uparrow) X Y(downarrow) bc+ 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.
@@ -13940,7 +14515,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stddef.h> /* ... */ wchar_t wstr[50]; - fscanf(stdin, "a%ls", wstr); + 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.
@@ -13950,7 +14526,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stddef.h> /* ... */ wchar_t wstr[50]; - fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr); + 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.
@@ -13961,7 +14538,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <stddef.h> /* ... */ wchar_t wstr[50]; - fscanf(stdin, "a(uparrow) Y(downarrow)%ls", wstr); + 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. @@ -13983,12 +14561,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
253) See ''future library directions'' (7.26.9).
-7.19.6.3 The printf function
+
#include <stdio.h>
- int printf(const char * restrict format, ...);
+ int printf(const char * restrict format, ...);
+
The printf function is equivalent to fprintf with the argument stdout interposed
@@ -13998,12 +14577,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The printf function returns the number of characters transmitted, or a negative value if
an output or encoding error occurred.
-7.19.6.4 The scanf function
+
#include <stdio.h>
- int scanf(const char * restrict format, ...);
+ int scanf(const char * restrict format, ...);
+
The scanf function is equivalent to fscanf with the argument stdin interposed
@@ -14015,13 +14595,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
assigned, which can be fewer than provided for, or even zero, in the event of an early
matching failure.
-7.19.6.5 The snprintf function
+
#include <stdio.h>
int snprintf(char * restrict s, size_t n,
- const char * restrict format, ...);
+ const char * restrict format, ...);
+
The snprintf function is equivalent to fprintf, except that the output is written into
@@ -14038,13 +14619,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.19.6.6 The sprintf function
+
#include <stdio.h>
int sprintf(char * restrict s,
- const char * restrict format, ...);
+ const char * restrict format, ...);
+
The sprintf function is equivalent to fprintf, except that the output is written into
@@ -14056,13 +14638,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.19.6.7 The sscanf function
+
#include <stdio.h>
int sscanf(const char * restrict s,
- const char * restrict format, ...);
+ const char * restrict format, ...);
+
The sscanf function is equivalent to fscanf, except that input is obtained from a
@@ -14077,7 +14660,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
early matching failure.
-7.19.6.8 The vfprintf function
+
@@ -14085,7 +14668,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <stdio.h>
int vfprintf(FILE * restrict stream,
const char * restrict format,
- va_list arg);
+ va_list arg);
+
The vfprintf function is equivalent to fprintf, with the variable argument list
@@ -14110,7 +14694,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
// print out remainder of message
vfprintf(stderr, format, args);
va_end(args);
- }
+ }
+
@@ -14122,7 +14707,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
vsscanf invoke the va_arg macro, the value of arg after the return is indeterminate.
-7.19.6.9 The vfscanf function
+
@@ -14130,13 +14715,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <stdio.h>
int vfscanf(FILE * restrict stream,
const char * restrict format,
- va_list arg);
+ va_list arg);
+
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.254) + va_end macro.254)
The vfscanf function returns the value of the macro EOF if an input failure occurs
@@ -14144,40 +14730,42 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-7.19.6.10 The vprintf function
+
#include <stdarg.h>
#include <stdio.h>
int vprintf(const char * restrict format,
- va_list arg);
+ va_list arg);
+
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 possibly subsequent va_arg calls). The vprintf function does not invoke the - va_end macro.254) + va_end macro.254)
The vprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
-7.19.6.11 The vscanf function
+
#include <stdarg.h>
#include <stdio.h>
int vscanf(const char * restrict format,
- va_list arg);
+ va_list arg);
+
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.254) + macro.254)
The vscanf function returns the value of the macro EOF if an input failure occurs
@@ -14185,7 +14773,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-7.19.6.12 The vsnprintf function
+
@@ -14193,13 +14781,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <stdio.h>
int vsnprintf(char * restrict s, size_t n,
const char * restrict format,
- va_list arg);
+ va_list arg);
+
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.254) If copying takes place between objects that overlap, the behavior is + va_end macro.254) If copying takes place between objects that overlap, the behavior is undefined.
@@ -14209,7 +14798,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
completely written if and only if the returned value is nonnegative and less than n.
-7.19.6.13 The vsprintf function
+
@@ -14217,20 +14806,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <stdio.h>
int vsprintf(char * restrict s,
const char * restrict format,
- va_list arg);
+ va_list arg);
+
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.254) If copying takes place between objects that overlap, the behavior is + va_end macro.254) If copying takes place between objects that overlap, the behavior is undefined.
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.
-7.19.6.14 The vsscanf function
+
@@ -14238,13 +14828,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <stdio.h>
int vsscanf(const char * restrict s,
const char * restrict format,
- va_list arg);
+ va_list arg);
+
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.254) + va_end macro.254)
The vsscanf function returns the value of the macro EOF if an input failure occurs
@@ -14253,14 +14844,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
early matching failure.
-7.19.7 Character input/output functions
+
#include <stdio.h>
- int fgetc(FILE *stream);
+ int fgetc(FILE *stream);
+
If the end-of-file indicator for the input stream pointed to by stream is not set and a @@ -14279,13 +14871,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
255) An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
-7.19.7.2 The fgets function
+
#include <stdio.h>
char *fgets(char * restrict s, int n,
- FILE * restrict stream);
+ FILE * restrict stream);
+
The fgets function reads at most one less than the number of characters specified by n
@@ -14304,12 +14897,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.19.7.3 The fputc function
+
#include <stdio.h>
- int fputc(int c, FILE *stream);
+ int fputc(int c, FILE *stream);
+
The fputc function writes the character specified by c (converted to an unsigned
@@ -14322,13 +14916,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fputc function returns the character written. If a write error occurs, the error
indicator for the stream is set and fputc returns EOF.
-7.19.7.4 The fputs function
+
#include <stdio.h>
int fputs(const char * restrict s,
- FILE * restrict stream);
+ FILE * restrict stream);
+
The fputs function writes the string pointed to by s to the stream pointed to by
@@ -14338,12 +14933,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The fputs function returns EOF if a write error occurs; otherwise it returns a
nonnegative value.
-7.19.7.5 The getc function
+
#include <stdio.h>
- int getc(FILE *stream);
+ int getc(FILE *stream);
+
The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
@@ -14357,12 +14953,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
getc returns EOF. If a read error occurs, the error indicator for the stream is set and
getc returns EOF.
-7.19.7.6 The getchar function
+
#include <stdio.h>
- int getchar(void);
+ int getchar(void);
+
The getchar function is equivalent to getc with the argument stdin.
@@ -14373,12 +14970,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
getchar returns EOF. If a read error occurs, the error indicator for the stream is set and
getchar returns EOF.
-7.19.7.7 The gets function
+
#include <stdio.h>
- char *gets(char *s);
+ char *gets(char *s);
+
The gets function reads characters from the input stream pointed to by stdin, into the @@ -14394,12 +14992,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: future library directions (7.26.9).
-7.19.7.8 The putc function
+
#include <stdio.h>
- int putc(int c, FILE *stream);
+ int putc(int c, FILE *stream);
+
The putc function is equivalent to fputc, except that if it is implemented as a macro, it
@@ -14410,12 +15009,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The putc function returns the character written. If a write error occurs, the error
indicator for the stream is set and putc returns EOF.
-7.19.7.9 The putchar function
+
#include <stdio.h>
- int putchar(int c);
+ int putchar(int c);
+
The putchar function is equivalent to putc with the second argument stdout.
@@ -14424,12 +15024,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The putchar function returns the character written. If a write error occurs, the error
indicator for the stream is set and putchar returns EOF.
-7.19.7.10 The puts function
+
#include <stdio.h>
- int puts(const char *s);
+ int puts(const char *s);
+
The puts function writes the string pointed to by s to the stream pointed to by stdout,
@@ -14441,12 +15042,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
value.
-7.19.7.11 The ungetc function
+
#include <stdio.h>
- int ungetc(int c, FILE *stream);
+ int ungetc(int c, FILE *stream);
+
The ungetc function pushes the character specified by c (converted to an unsigned @@ -14486,16 +15088,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
256) See ''future library directions'' (7.26.9).
-7.19.8 Direct input/output functions
+
#include <stdio.h>
size_t fread(void * restrict ptr,
size_t size, size_t nmemb,
- FILE * restrict stream);
+ FILE * restrict stream);
+
The fread function reads, into the array pointed to by ptr, up to nmemb elements
@@ -14512,14 +15115,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
fread returns zero and the contents of the array and the state of the stream remain
unchanged.
-7.19.8.2 The fwrite function
+
#include <stdio.h>
size_t fwrite(const void * restrict ptr,
size_t size, size_t nmemb,
- FILE * restrict stream);
+ FILE * restrict stream);
+
The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
@@ -14536,15 +15140,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.19.9 File positioning functions
+
#include <stdio.h>
int fgetpos(FILE * restrict stream,
- fpos_t * restrict pos);
+ fpos_t * restrict pos);
+
The fgetpos function stores the current values of the parse state (if any) and file @@ -14557,12 +15162,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 returns nonzero and stores an implementation-defined positive value in errno.
Forward references: the fsetpos function (7.19.9.3).
-7.19.9.2 The fseek function
+
#include <stdio.h>
- int fseek(FILE *stream, long int offset, int whence);
+ int fseek(FILE *stream, long int offset, int whence);
+
The fseek function sets the file position indicator for the stream pointed to by stream. @@ -14588,12 +15194,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The fseek function returns nonzero only for a request that cannot be satisfied.
Forward references: the ftell function (7.19.9.4).
-7.19.9.3 The fsetpos function
+
#include <stdio.h>
- int fsetpos(FILE *stream, const fpos_t *pos);
+ int fsetpos(FILE *stream, const fpos_t *pos);
+
The fsetpos function sets the mbstate_t object (if any) and file position indicator
@@ -14611,12 +15218,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
If successful, the fsetpos function returns zero; on failure, the fsetpos function
returns nonzero and stores an implementation-defined positive value in errno.
-7.19.9.4 The ftell function
+
#include <stdio.h>
- long int ftell(FILE *stream);
+ long int ftell(FILE *stream);
+
The ftell function obtains the current value of the file position indicator for the stream
@@ -14633,31 +15241,34 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
for the stream. On failure, the ftell function returns -1L and stores an
implementation-defined positive value in errno.
-7.19.9.5 The rewind function
+
#include <stdio.h>
- void rewind(FILE *stream);
+ void rewind(FILE *stream);
+
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)+ (void)fseek(stream, 0L, SEEK_SET) + except that the error indicator for the stream is also cleared.
The rewind function returns no value.
-7.19.10 Error-handling functions
+
#include <stdio.h>
- void clearerr(FILE *stream);
+ void clearerr(FILE *stream);
+
The clearerr function clears the end-of-file and error indicators for the stream pointed
@@ -14667,12 +15278,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The clearerr function returns no value.
-7.19.10.2 The feof function
+
#include <stdio.h>
- int feof(FILE *stream);
+ int feof(FILE *stream);
+
The feof function tests the end-of-file indicator for the stream pointed to by stream.
@@ -14681,12 +15293,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The feof function returns nonzero if and only if the end-of-file indicator is set for
stream.
-7.19.10.3 The ferror function
+
#include <stdio.h>
- int ferror(FILE *stream);
+ int ferror(FILE *stream);
+
The ferror function tests the error indicator for the stream pointed to by stream.
@@ -14695,12 +15308,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The ferror function returns nonzero if and only if the error indicator is set for
stream.
-7.19.10.4 The perror function
+
#include <stdio.h>
- void perror(const char *s);
+ void perror(const char *s);
+
The perror function maps the error number in the integer expression errno to an @@ -14715,37 +15329,44 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: the strerror function (7.21.6.2).
-7.20 General utilities
+
The header <stdlib.h> declares five types and several functions of general utility, and defines several macros.257)
The types declared are size_t and wchar_t (both described in 7.17),
- div_t+ div_t + which is a structure type that is the type of the value returned by the div function,
- ldiv_t+ ldiv_t + which is a structure type that is the type of the value returned by the ldiv function, and
- lldiv_t+ lldiv_t + which is a structure type that is the type of the value returned by the lldiv function.
The macros defined are NULL (described in 7.17);
- EXIT_FAILURE+ EXIT_FAILURE + and
- EXIT_SUCCESS+ 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+ RAND_MAX + which expands to an integer constant expression that is the maximum value returned by the rand function; and
- MB_CUR_MAX+ 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. @@ -14759,37 +15380,40 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
257) See ''future library directions'' (7.26.10).
-7.20.1 Numeric conversion functions
+
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.
-7.20.1.1 The atof function
+
#include <stdlib.h>
- double atof(const char *nptr);
+ double atof(const char *nptr);
+
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)+ strtod(nptr, (char **)NULL) +
The atof function returns the converted value.
Forward references: the strtod, strtof, and strtold functions (7.20.1.3).
-7.20.1.2 The atoi, atol, and atoll functions
+
#include <stdlib.h>
int atoi(const char *nptr);
long int atol(const char *nptr);
- long long int atoll(const char *nptr);
+ long long int atoll(const char *nptr);
+
The atoi, atol, and atoll functions convert the initial portion of the string pointed @@ -14798,7 +15422,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
atoi: (int)strtol(nptr, (char **)NULL, 10)
atol: strtol(nptr, (char **)NULL, 10)
- atoll: strtoll(nptr, (char **)NULL, 10)
+ atoll: strtoll(nptr, (char **)NULL, 10)
+
The atoi, atol, and atoll functions return the converted value.
@@ -14806,7 +15431,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(7.20.1.4).
-7.20.1.3 The strtod, strtof, and strtold functions
+
@@ -14816,7 +15441,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
float strtof(const char * restrict nptr,
char ** restrict endptr);
long double strtold(const char * restrict nptr,
- char ** restrict endptr);
+ char ** restrict endptr);
+
The strtod, strtof, and strtold functions convert the initial portion of the string @@ -14836,13 +15462,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
n-char-sequence:
digit
nondigit
n-char-sequence digit
- n-char-sequence nondigit
+ 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
@@ -14859,7 +15486,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the subject sequence begins with a minus sign, the sequence is interpreted as negated.258)
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
+ 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.259) A
pointer to the final string is stored in the object pointed to by endptr, provided that
@@ -14874,7 +15501,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
@@ -14916,7 +15543,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
to the same internal floating value, but if not will round to adjacent values.
-7.20.1.4 The strtol, strtoll, strtoul, and strtoull functions
+
@@ -14936,7 +15563,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
unsigned long long int strtoull(
const char * restrict nptr,
char ** restrict endptr,
- int base);
+ int base);
+
The strtol, strtoll, strtoul, and strtoull functions convert the initial
@@ -14991,14 +15619,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
and sign of the value, if any), and the value of the macro ERANGE is stored in errno.
-7.20.2 Pseudo-random sequence generation functions
+
#include <stdlib.h>
- int rand(void);
+ int rand(void);
+
The rand function computes a sequence of pseudo-random integers in the range 0 to @@ -15008,16 +15637,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The rand function returns a pseudo-random integer. - Environmental limits +
The value of the RAND_MAX macro shall be at least 32767.
-7.20.2.2 The srand function
+
#include <stdlib.h>
- void srand(unsigned int seed);
+ void srand(unsigned int seed);
+
The srand function uses the argument as a seed for a new sequence of pseudo-random
@@ -15043,10 +15673,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
void srand(unsigned int seed)
{
next = seed;
- }
+ }
+
-7.20.3 Memory management functions
+
The order and contiguity of storage allocated by successive calls to the calloc,
malloc, and realloc functions is unspecified. The pointer returned if the allocation
@@ -15060,12 +15691,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.20.3.1 The calloc function
+
#include <stdlib.h>
- void *calloc(size_t nmemb, size_t size);
+ void *calloc(size_t nmemb, size_t size);
+
The calloc function allocates space for an array of nmemb objects, each of whose size
@@ -15079,12 +15711,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
constant.
-7.20.3.2 The free function
+
#include <stdlib.h>
- void free(void *ptr);
+ void free(void *ptr);
+
The free function causes the space pointed to by ptr to be deallocated, that is, made @@ -15099,12 +15732,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The free function returns no value.
-7.20.3.3 The malloc function
+
#include <stdlib.h>
- void *malloc(size_t size);
+ void *malloc(size_t size);
+
The malloc function allocates space for an object whose size is specified by size and @@ -15113,12 +15747,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The malloc function returns either a null pointer or a pointer to the allocated space.
-7.20.3.4 The realloc function
+
#include <stdlib.h>
- void *realloc(void *ptr, size_t size);
+ void *realloc(void *ptr, size_t size);
+
The realloc function deallocates the old object pointed to by ptr and returns a
@@ -15139,14 +15774,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
allocated.
-7.20.4 Communication with the environment
+
#include <stdlib.h>
- void abort(void);
+ void abort(void);
+
The abort function causes abnormal program termination to occur, unless the signal @@ -15159,17 +15795,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The abort function does not return to its caller.
-7.20.4.2 The atexit function
+
#include <stdlib.h>
- int atexit(void (*func)(void));
+ int atexit(void (*func)(void));
+
The atexit function registers the function pointed to by func, to be called without arguments at normal program termination. - Environmental limits +
The implementation shall support the registration of at least 32 functions.
Forward references: the exit function (7.20.4.3).
-7.20.4.3 The exit function
+
#include <stdlib.h>
- void exit(int status);
+ void exit(int status);
+
The exit function causes normal program termination to occur. If more than one call to
@@ -15212,12 +15850,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
other registered functions.
-7.20.4.4 The _Exit function
+
#include <stdlib.h>
- void _Exit(int status);
+ void _Exit(int status);
+
The _Exit function causes normal program termination to occur and control to be
@@ -15235,12 +15874,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.20.4.5 The getenv function
+
#include <stdlib.h>
- char *getenv(const char *name);
+ char *getenv(const char *name);
+
The getenv function searches an environment list, provided by the host environment,
@@ -15255,12 +15895,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
overwritten by a subsequent call to the getenv function. If the specified name cannot
be found, a null pointer is returned.
-7.20.4.6 The system function
+
#include <stdlib.h>
- int system(const char *string);
+ int system(const char *string);
+
If string is a null pointer, the system function determines whether the host
@@ -15275,7 +15916,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
function does return, it returns an implementation-defined value.
-7.20.5 Searching and sorting utilities
+
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 @@ -15309,17 +15950,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
((char *)p - (char *)base) % size == 0
(char *)p >= (char *)base
- (char *)p < (char *)base + nmemb * size
+ (char *)p < (char *)base + nmemb * size
+
-
#include <stdlib.h>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
- int (*compar)(const void *, const void *));
+ int (*compar)(const void *, const void *));
+
The bsearch function searches an array of nmemb objects, the initial element of which @@ -15345,13 +15988,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
264) In practice, the entire array is sorted according to the comparison function.
-7.20.5.2 The qsort function
+
#include <stdlib.h>
void qsort(void *base, size_t nmemb, size_t size,
- int (*compar)(const void *, const void *));
+ int (*compar)(const void *, const void *));
+
The qsort function sorts an array of nmemb objects, the initial element of which is
@@ -15373,16 +16017,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.20.6 Integer arithmetic functions
+
#include <stdlib.h>
int abs(int j);
long int labs(long int j);
- long long int llabs(long long int j);
+ long long int llabs(long long int j);
+
The abs, labs, and llabs functions compute the absolute value of an integer j. If the @@ -15395,14 +16040,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
265) The absolute value of the most negative number cannot be represented in two's complement.
-7.20.6.2 The div, ldiv, and lldiv functions
+
#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);
+ lldiv_t lldiv(long long int numer, long long int denom);
+
The div, ldiv, and lldiv, functions compute numer / denom and numer %
@@ -15420,7 +16066,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.20.7 Multibyte/wide character conversion functions
+
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
@@ -15436,12 +16082,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character codes, but are grouped with an adjacent multibyte character.
-7.20.7.1 The mblen function
+
#include <stdlib.h>
- int mblen(const char *s, size_t n);
+ int mblen(const char *s, size_t n);
+
If s is not a null pointer, the mblen function determines the number of bytes contained @@ -15449,7 +16096,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 mbtowc function is not affected, it is equivalent to
- mbtowc((wchar_t *)0, s, n);+ mbtowc((wchar_t *)0, s, n); + The implementation shall behave as if no library function calls the mblen function.
@@ -15466,14 +16114,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.20.7.2 The mbtowc function
+
#include <stdlib.h>
int mbtowc(wchar_t * restrict pwc,
const char * restrict s,
- size_t n);
+ size_t n);
+
If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with
@@ -15497,12 +16146,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
In no case will the value returned be greater than n or the value of the MB_CUR_MAX
macro.
-7.20.7.3 The wctomb function
+
#include <stdlib.h>
- int wctomb(char *s, wchar_t wc);
+ int wctomb(char *s, wchar_t wc);
+
The wctomb function determines the number of bytes needed to represent the multibyte @@ -15525,19 +16175,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
In no case will the value returned be greater than the value of the MB_CUR_MAX macro.
-7.20.8 Multibyte/wide string conversion functions
+
The behavior of the multibyte string functions is affected by the LC_CTYPE category of
the current locale.
-7.20.8.1 The mbstowcs function
+
#include <stdlib.h>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s,
- size_t n);
+ size_t n);
+
The mbstowcs function converts a sequence of multibyte characters that begins in the @@ -15565,14 +16216,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
267) The array will not be null-terminated if the value returned is n.
-7.20.8.2 The wcstombs function
+
#include <stdlib.h>
size_t wcstombs(char * restrict s,
const wchar_t * restrict pwcs,
- size_t n);
+ size_t n);
+
The wcstombs function converts a sequence of wide characters from the array pointed
@@ -15589,12 +16241,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.267)
+ any.267)
-7.21 String handling
+
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 @@ -15619,16 +16271,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
268) See ''future library directions'' (7.26.11).
-7.21.2 Copying functions
+
#include <string.h>
void *memcpy(void * restrict s1,
const void * restrict s2,
- size_t n);
+ size_t n);
+
The memcpy function copies n characters from the object pointed to by s2 into the
@@ -15643,12 +16296,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.21.2.2 The memmove function
+
#include <string.h>
- void *memmove(void *s1, const void *s2, size_t n);
+ void *memmove(void *s1, const void *s2, size_t n);
+
The memmove function copies n characters from the object pointed to by s2 into the @@ -15660,13 +16314,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The memmove function returns the value of s1.
-7.21.2.3 The strcpy function
+
#include <string.h>
char *strcpy(char * restrict s1,
- const char * restrict s2);
+ const char * restrict s2);
+
The strcpy function copies the string pointed to by s2 (including the terminating null @@ -15676,14 +16331,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The strcpy function returns the value of s1.
-7.21.2.4 The strncpy function
+
#include <string.h>
char *strncpy(char * restrict s1,
const char * restrict s2,
- size_t n);
+ size_t n);
+
The strncpy function copies not more than n characters (characters that follow a null
@@ -15703,15 +16359,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
not be null-terminated.
-7.21.3 Concatenation functions
+
#include <string.h>
char *strcat(char * restrict s1,
- const char * restrict s2);
+ const char * restrict s2);
+
The strcat function appends a copy of the string pointed to by s2 (including the @@ -15722,14 +16379,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The strcat function returns the value of s1.
-7.21.3.2 The strncat function
+
#include <string.h>
char *strncat(char * restrict s1,
const char * restrict s2,
- size_t n);
+ size_t n);
+
The strncat function appends not more than n characters (a null character and
@@ -15749,19 +16407,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
strlen(s1)+n+1.
-7.21.4 Comparison functions
+
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.
-7.21.4.1 The memcmp function
+
#include <string.h>
- int memcmp(const void *s1, const void *s2, size_t n);
+ int memcmp(const void *s1, const void *s2, size_t n);
+
The memcmp function compares the first n characters of the object pointed to by s1 to
@@ -15778,12 +16437,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
comparison.
-7.21.4.2 The strcmp function
+
#include <string.h>
- int strcmp(const char *s1, const char *s2);
+ int strcmp(const char *s1, const char *s2);
+
The strcmp function compares the string pointed to by s1 to the string pointed to by
@@ -15796,12 +16456,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
pointed to by s2.
-7.21.4.3 The strcoll function
+
#include <string.h>
- int strcoll(const char *s1, const char *s2);
+ int strcoll(const char *s1, const char *s2);
+
The strcoll function compares the string pointed to by s1 to the string pointed to by
@@ -15812,12 +16473,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.21.4.4 The strncmp function
+
#include <string.h>
- int strncmp(const char *s1, const char *s2, size_t n);
+ int strncmp(const char *s1, const char *s2, size_t n);
+
The strncmp function compares not more than n characters (characters that follow a
@@ -15829,14 +16491,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.21.4.5 The strxfrm function
+
#include <string.h>
size_t strxfrm(char * restrict s1,
const char * restrict s2,
- size_t n);
+ size_t n);
+
The strxfrm function transforms the string pointed to by s2 and places the resulting @@ -15857,17 +16520,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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)+ 1 + strxfrm(NULL, s, 0) + -
#include <string.h>
- void *memchr(const void *s, int c, size_t n);
+ void *memchr(const void *s, int c, size_t n);
+
The memchr function locates the first occurrence of c (converted to an unsigned
@@ -15878,12 +16543,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The memchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the object.
-7.21.5.2 The strchr function
+
#include <string.h>
- char *strchr(const char *s, int c);
+ char *strchr(const char *s, int c);
+
The strchr function locates the first occurrence of c (converted to a char) in the
@@ -15895,12 +16561,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character does not occur in the string.
-7.21.5.3 The strcspn function
+
#include <string.h>
- size_t strcspn(const char *s1, const char *s2);
+ size_t strcspn(const char *s1, const char *s2);
+
The strcspn function computes the length of the maximum initial segment of the string @@ -15910,12 +16577,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The strcspn function returns the length of the segment.
-7.21.5.4 The strpbrk function
+
#include <string.h>
- char *strpbrk(const char *s1, const char *s2);
+ char *strpbrk(const char *s1, const char *s2);
+
The strpbrk function locates the first occurrence in the string pointed to by s1 of any
@@ -15925,12 +16593,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The strpbrk function returns a pointer to the character, or a null pointer if no character
from s2 occurs in s1.
-7.21.5.5 The strrchr function
+
#include <string.h>
- char *strrchr(const char *s, int c);
+ char *strrchr(const char *s, int c);
+
The strrchr function locates the last occurrence of c (converted to a char) in the
@@ -15942,12 +16611,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
occur in the string.
-7.21.5.6 The strspn function
+
#include <string.h>
- size_t strspn(const char *s1, const char *s2);
+ size_t strspn(const char *s1, const char *s2);
+
The strspn function computes the length of the maximum initial segment of the string @@ -15956,12 +16626,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The strspn function returns the length of the segment.
-7.21.5.7 The strstr function
+
#include <string.h>
- char *strstr(const char *s1, const char *s2);
+ char *strstr(const char *s1, const char *s2);
+
The strstr function locates the first occurrence in the string pointed to by s1 of the
@@ -15972,13 +16643,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.21.5.8 The strtok function
+
#include <string.h>
char *strtok(char * restrict s1,
- const char * restrict s2);
+ const char * restrict s2);
+
A sequence of calls to the strtok function breaks the string pointed to by s1 into a
@@ -16017,17 +16689,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+ t = strtok(NULL, "?"); // t is a null pointer
+
-7.21.6 Miscellaneous functions
+
#include <string.h>
- void *memset(void *s, int c, size_t n);
+ void *memset(void *s, int c, size_t n);
+
The memset function copies the value of c (converted to an unsigned char) into
@@ -16037,12 +16711,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The memset function returns the value of s.
-7.21.6.2 The strerror function
+
#include <string.h>
- char *strerror(int errnum);
+ char *strerror(int errnum);
+
The strerror function maps the number in errnum to a message string. Typically,
@@ -16056,12 +16731,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
specific. The array pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the strerror function.
-7.21.6.3 The strlen function
+
#include <string.h>
- size_t strlen(const char *s);
+ size_t strlen(const char *s);
+
The strlen function computes the length of the string pointed to by s.
@@ -16071,7 +16747,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character.
-7.22 Type-generic math
+
The header <tgmath.h> includes the headers <math.h> and <complex.h> and defines several type-generic macros. @@ -16106,6 +16782,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
<math.h> <complex.h> type-generic
function function macro
+
acos cacos acos
asin casin asin
atan catan atan
@@ -16122,7 +16799,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
log clog log
pow cpow pow
sqrt csqrt sqrt
- fabs cabs fabs
+ 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.
@@ -16139,7 +16817,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 exp2 ilogb lround tgamma expm1 ldexp nearbyint trunc fdim lgamma nextafter - floor llrint nexttoward + 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.
@@ -16149,7 +16828,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
carg conj creal
- cimag cproj
+ cimag cproj
+
Use of the macro with any real or complex argument invokes a complex function.
EXAMPLE With the declarations @@ -16161,11 +16841,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 long double ld; float complex fc; double complex dc; - long double complex ldc; + long double complex ldc; + functions invoked by use of type-generic macros are shown in the following table:
- macro use invokes
+ macro use invokes
+
exp(n) exp(n), the function
acosh(f) acoshf(f)
sin(d) sin(d), the function
@@ -16186,7 +16868,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
cimag(ld) cimagl(ld)
fabs(fc) cabsf(fc)
carg(dc) carg(dc), the function
- cproj(ldc) cprojl(ldc)
+ cproj(ldc) cprojl(ldc)
+
272) Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to
@@ -16196,9 +16879,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the behavior is undefined.
-7.23 Date and time
+
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 @@ -16209,19 +16892,23 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The macros defined are NULL (described in 7.17); and
- CLOCKS_PER_SEC+ 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.
The types declared are size_t (described in 7.17);
- clock_t+ clock_t + and
- time_t+ time_t + which are arithmetic types capable of representing times; and
- struct tm+ struct tm + which holds the components of a calendar time, called the broken-down time.
The range and precision of times representable in clock_t and time_t are @@ -16237,7 +16924,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 + int tm_isdst; // Daylight Saving Time flag + @@ -16249,14 +16937,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
274) The range [0, 60] for tm_sec allows for a positive leap second.
-7.23.2 Time manipulation functions
+
#include <time.h>
- clock_t clock(void);
+ clock_t clock(void);
+
The clock function determines the processor time used.
@@ -16274,12 +16963,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the program and its return value subtracted from the value returned by subsequent calls.
-7.23.2.2 The difftime function
+
#include <time.h>
- double difftime(time_t time1, time_t time0);
+ double difftime(time_t time1, time_t time0);
+
The difftime function computes the difference between two calendar times: time1 -
@@ -16293,12 +16983,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.23.2.3 The mktime function
+
#include <time.h>
- time_t mktime(struct tm *timeptr);
+ time_t mktime(struct tm *timeptr);
+
The mktime function converts the broken-down time, expressed as local time, in the @@ -16325,7 +17016,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 "Thursday", "Friday", "Saturday", "-unknown-" }; struct tm time_str; - /* ... */ + /* ... */ + @@ -16341,7 +17033,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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]); + printf("%s\n", wday[time_str.tm_wday]); +
#include <time.h>
- time_t time(time_t *timer);
+ time_t time(time_t *timer);
+
The time function determines the current calendar time. The encoding of the value is
@@ -16367,7 +17061,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
available. If timer is not a null pointer, the return value is also assigned to the object it
points to.
-7.23.3 Time conversion functions
+
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
@@ -16376,23 +17070,25 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
previous call to any of them. The implementation shall behave as if no other library
functions call these functions.
-7.23.3.1 The asctime function
+
#include <time.h>
- char *asctime(const struct tm *timeptr);
+ char *asctime(const struct tm *timeptr);
+
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+ Sun Sep 16 01:03:52 1973\n\0 + 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"
};
@@ -16407,24 +17103,27 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
timeptr->tm_mday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec,
1900 + timeptr->tm_year);
- return result;
+ return result;
}
+
The asctime function returns a pointer to the string.
-7.23.3.2 The ctime function
+
#include <time.h>
- char *ctime(const time_t *timer);
+ char *ctime(const time_t *timer);
+
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))+ asctime(localtime(timer)) +
The ctime function returns the pointer returned by the asctime function with that @@ -16432,12 +17131,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: the localtime function (7.23.3.4).
-7.23.3.3 The gmtime function
+
#include <time.h>
- struct tm *gmtime(const time_t *timer);
+ struct tm *gmtime(const time_t *timer);
+
The gmtime function converts the calendar time pointed to by timer into a broken-
@@ -16447,12 +17147,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The gmtime function returns a pointer to the broken-down time, or a null pointer if the
specified time cannot be converted to UTC.
-7.23.3.4 The localtime function
+
#include <time.h>
- struct tm *localtime(const time_t *timer);
+ struct tm *localtime(const time_t *timer);
+
The localtime function converts the calendar time pointed to by timer into a
@@ -16462,7 +17163,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.23.3.5 The strftime function
+
@@ -16470,7 +17171,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
- const struct tm * restrict timeptr);
+ const struct tm * restrict timeptr);
+
The strftime function places characters into the array pointed to by s as controlled by @@ -16489,125 +17191,102 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 7.23.1]- %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. - %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 7.23.1] - %X is replaced by the locale's appropriate time representation. [all specified in 7.23.1] - %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 -
+ tm_sec] +
- time zone is determinable. [tm_isdst]- %% is replaced by %. + zone is determinable. [tm_isdst] +
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. - %Od 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 + symbol for zero). +
- 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. +
-
- symbols.%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 @@ -16622,16 +17301,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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''. - %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. +
@@ -16641,33 +17322,37 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
zero is returned and the contents of the array are indeterminate.
-7.24 Extended multibyte and wide character utilities
+
The header <wchar.h> declares four data types, one tag, four macros, and many functions.277)
The types declared are wchar_t and size_t (both described in 7.17);
- mbstate_t+ mbstate_t + which is an 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+ 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);278) and
- struct tm+ struct tm + which is declared as an incomplete structure type (the contents are described in 7.23.1).
The macros defined are NULL (described in 7.17); WCHAR_MIN and WCHAR_MAX (described in 7.18.3); and
- WEOF+ WEOF + which expands to a constant expression of type wint_t whose value does not correspond to any member of the extended character set.279) It is accepted (and returned) by several functions in this subclause to indicate end-of-file, that is, no more input from a @@ -16700,7 +17385,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
279) The value of the macro WEOF may differ from that of EOF and need not be negative.
-7.24.2 Formatted wide character input/output functions
+
The formatted wide character input/output functions shall behave as if there is a sequence point after the actions associated with each specifier.280) @@ -16709,14 +17394,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
280) The fwprintf functions perform writes to memory for the %n specifier.
-7.24.2.1 The fwprintf function
+
#include <stdio.h>
#include <wchar.h>
int fwprintf(FILE * restrict stream,
- const wchar_t * restrict format, ...);
+ const wchar_t * restrict format, ...);
+
The fwprintf function writes output to the stream pointed to by stream, under @@ -16766,105 +17452,93 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 precision were omitted.
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 -
+
+ specified.)282) +
+ space and + flags both appear, the space flag is ignored. +
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
--
+ result. For other conversions, the behavior is undefined. +
The length modifiers and their meanings are: - hh Specifies that a following d, i, o, u, x, or X conversion specifier applies to a -
+
+ argument. +
+ int argument. +
+ specifier. +
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
-+ specifier applies to a pointer to an intmax_t argument. +
+ corresponding to size_t argument. +
- applies to a long double argument.+ argument. +
The conversion specifiers and their meanings are: - d,i The int argument is converted to signed decimal in the style [-]dddd. The -
+
+ value with a precision of zero is no wide characters. +
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
@@ -16877,9 +17551,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
[-]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
- nan, respectively.283)
- e,E A double argument representing a floating-point number is converted in the
-+ nan, respectively.283) +
+ of an f or F conversion specifier. +
+ of an f or F conversion specifier. +
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
distinguish285) values of type double, except that trailing zeros may be
@@ -16927,14 +17597,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
-+ of an f or F conversion specifier. +
+ wchar_t and written. +
- converted to a sequence of printing wide characters, in an implementation-- + shall contain a null wide character. +
- defined manner.- n The argument shall be a pointer to signed integer into which is written the -
+ defined manner. +
-
- conversion specification shall be %%.If a conversion specification is invalid, the behavior is undefined.286) If any argument is not the correct type for the corresponding conversion specification, the behavior is undefined. @@ -16977,7 +17641,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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 +
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 @@ -16998,7 +17662,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 value if an output or encoding error occurred. - Environmental limits +
The number of wide characters that can be produced by any single conversion shall be at least 4095. @@ -17014,7 +17678,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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)); + fwprintf(stdout, L"pi = %.5f\n", 4 * atan(1.0)); +
Forward references: the btowc function (7.24.6.1.1), the mbrtowc function (7.24.6.3.2). @@ -17031,7 +17696,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
284) 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. -
285) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is +
285) The precision p is sufficient to distinguish values of the source type if 16p-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.
@@ -17043,14 +17708,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the case of fixed-point conversion by the source value as well.
-7.24.2.2 The fwscanf function
+
#include <stdio.h>
#include <wchar.h>
int fwscanf(FILE * restrict stream,
- const wchar_t * restrict format, ...);
+ const wchar_t * restrict format, ...);
+
The fwscanf function reads input from the stream pointed to by stream, under @@ -17118,73 +17784,61 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 represented in the object, the behavior is undefined.
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 -
+
+ int. +
+ conversion specifier applies to an argument with type pointer to wchar_t. +
- 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 -
+ long long int. +
+ integer type. +
- applies to an argument with type pointer to long double.+ unsigned integer type. +
The conversion specifiers and their meanings are: - d Matches an optionally signed decimal integer, whose format is the same as -
+
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
- integer.
- o Matches an optionally signed octal integer, whose format is the same as
-+ integer. +
+ unsigned integer. +
+ unsigned integer. +
+ unsigned integer. +
+ function. The corresponding argument shall be a pointer to floating. +
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
@@ -17208,9 +17861,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
- [ Matches a nonempty sequence of wide characters from a set of expected
-+ automatically. +
+ last character, the behavior is implementation-defined. +
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
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
+ undefined.
+-
- complete conversion specification shall be %%.If a conversion specification is invalid, the behavior is undefined.290)
The conversion specifiers A, E, F, G, and X are also valid and behave the same as, @@ -17278,10 +17928,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <wchar.h> /* ... */ int n, i; float x; wchar_t name[50]; - n = fwscanf(stdin, L"%d%f%ls", &i, &x, name); + n = fwscanf(stdin, L"%d%f%ls", &i, &x, name); + with the input line:
- 25 54.32E-1 thompson+ 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. @@ -17292,10 +17944,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 #include <wchar.h> /* ... */ int i; float x; double y; - fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y); + fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y); + with input:
- 56789 0123 56a72+ 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. @@ -17314,14 +17968,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
290) See ''future library directions'' (7.26.12).
-7.24.2.3 The swprintf function
+
#include <wchar.h>
int swprintf(wchar_t * restrict s,
size_t n,
- const wchar_t * restrict format, ...);
+ const wchar_t * restrict format, ...);
+
The swprintf function is equivalent to fwprintf, except that the argument s
@@ -17334,13 +17989,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.2.4 The swscanf function
+
#include <wchar.h>
int swscanf(const wchar_t * restrict s,
- const wchar_t * restrict format, ...);
+ const wchar_t * restrict format, ...);
+
The swscanf function is equivalent to fwscanf, except that the argument s specifies a
@@ -17355,7 +18011,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
early matching failure.
-7.24.2.5 The vfwprintf function
+
@@ -17364,7 +18020,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <wchar.h>
int vfwprintf(FILE * restrict stream,
const wchar_t * restrict format,
- va_list arg);
+ va_list arg);
+
The vfwprintf function is equivalent to fwprintf, with the variable argument list
@@ -17391,7 +18048,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
// print out remainder of message
vfwprintf(stderr, format, args);
va_end(args);
- }
+ }
+
@@ -17403,7 +18061,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
invoke the va_arg macro, the value of arg after the return is indeterminate.
-7.24.2.6 The vfwscanf function
+
@@ -17412,13 +18070,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <wchar.h>
int vfwscanf(FILE * restrict stream,
const wchar_t * restrict format,
- va_list arg);
+ va_list arg);
+
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.291) + va_end macro.291)
The vfwscanf function returns the value of the macro EOF if an input failure occurs
@@ -17426,7 +18085,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-7.24.2.7 The vswprintf function
+
@@ -17435,13 +18094,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int vswprintf(wchar_t * restrict s,
size_t n,
const wchar_t * restrict format,
- va_list arg);
+ va_list arg);
+
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.291) + va_end macro.291)
The vswprintf function returns the number of wide characters written in the array, not
@@ -17449,7 +18109,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
occurred or if n or more wide characters were requested to be generated.
-7.24.2.8 The vswscanf function
+
@@ -17457,13 +18117,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#include <wchar.h>
int vswscanf(const wchar_t * restrict s,
const wchar_t * restrict format,
- va_list arg);
+ va_list arg);
+
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.291) + va_end macro.291)
The vswscanf function returns the value of the macro EOF if an input failure occurs
@@ -17471,40 +18132,42 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-7.24.2.9 The vwprintf function
+
#include <stdarg.h>
#include <wchar.h>
int vwprintf(const wchar_t * restrict format,
- va_list arg);
+ va_list arg);
+
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.291) + va_end macro.291)
The vwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-7.24.2.10 The vwscanf function
+
#include <stdarg.h>
#include <wchar.h>
int vwscanf(const wchar_t * restrict format,
- va_list arg);
+ va_list arg);
+
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.291) + va_end macro.291)
The vwscanf function returns the value of the macro EOF if an input failure occurs
@@ -17512,12 +18175,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-7.24.2.11 The wprintf function
+
#include <wchar.h>
- int wprintf(const wchar_t * restrict format, ...);
+ int wprintf(const wchar_t * restrict format, ...);
+
The wprintf function is equivalent to fwprintf with the argument stdout
@@ -17527,12 +18191,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-7.24.2.12 The wscanf function
+
#include <wchar.h>
- int wscanf(const wchar_t * restrict format, ...);
+ int wscanf(const wchar_t * restrict format, ...);
+
The wscanf function is equivalent to fwscanf with the argument stdin interposed
@@ -17545,15 +18210,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-7.24.3 Wide character input/output functions
+
#include <stdio.h>
#include <wchar.h>
- wint_t fgetwc(FILE *stream);
+ wint_t fgetwc(FILE *stream);
+
If the end-of-file indicator for the input stream pointed to by stream is not set and a
@@ -17574,14 +18240,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Also, errno will be set to EILSEQ by input/output functions only if an encoding error occurs.
-7.24.3.2 The fgetws function
+
#include <stdio.h>
#include <wchar.h>
wchar_t *fgetws(wchar_t * restrict s,
- int n, FILE * restrict stream);
+ int n, FILE * restrict stream);
+
The fgetws function reads at most one less than the number of wide characters
@@ -17599,13 +18266,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.3.3 The fputwc function
+
#include <stdio.h>
#include <wchar.h>
- wint_t fputwc(wchar_t c, FILE *stream);
+ wint_t fputwc(wchar_t c, FILE *stream);
+
The fputwc function writes the wide character specified by c to the output stream
@@ -17619,14 +18287,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.3.4 The fputws function
+
#include <stdio.h>
#include <wchar.h>
int fputws(const wchar_t * restrict s,
- FILE * restrict stream);
+ FILE * restrict stream);
+
The fputws function writes the wide string pointed to by s to the stream pointed to by
@@ -17637,13 +18306,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
returns a nonnegative value.
-7.24.3.5 The fwide function
+
#include <stdio.h>
#include <wchar.h>
- int fwide(FILE *stream, int mode);
+ int fwide(FILE *stream, int mode);
+
The fwide function determines the orientation of the stream pointed to by stream. If @@ -17660,13 +18330,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
293) If the orientation of the stream has already been determined, fwide does not change it.
-7.24.3.6 The getwc function
+
#include <stdio.h>
#include <wchar.h>
- wint_t getwc(FILE *stream);
+ wint_t getwc(FILE *stream);
+
The getwc function is equivalent to fgetwc, except that if it is implemented as a
@@ -17677,12 +18348,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The getwc function returns the next wide character from the input stream pointed to by
stream, or WEOF.
-7.24.3.7 The getwchar function
+
#include <wchar.h>
- wint_t getwchar(void);
+ wint_t getwchar(void);
+
@@ -17696,13 +18368,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The getwchar function returns the next wide character from the input stream pointed to
by stdin, or WEOF.
-
#include <stdio.h>
#include <wchar.h>
- wint_t putwc(wchar_t c, FILE *stream);
+ wint_t putwc(wchar_t c, FILE *stream);
+
The putwc function is equivalent to fputwc, except that if it is implemented as a @@ -17712,12 +18385,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The putwc function returns the wide character written, or WEOF.
-7.24.3.9 The putwchar function
+
#include <wchar.h>
- wint_t putwchar(wchar_t c);
+ wint_t putwchar(wchar_t c);
+
The putwchar function is equivalent to putwc with the second argument stdout. @@ -17725,13 +18399,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The putwchar function returns the character written, or WEOF.
-7.24.3.10 The ungetwc function
+
#include <stdio.h>
#include <wchar.h>
- wint_t ungetwc(wint_t c, FILE *stream);
+ wint_t ungetwc(wint_t c, FILE *stream);
+
The ungetwc function pushes the wide character specified by c back onto the input
@@ -17762,7 +18437,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The ungetwc function returns the wide character pushed back, or WEOF if the operation
fails.
-7.24.4 General wide string utilities
+
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
@@ -17778,9 +18453,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
zero wide characters.
-7.24.4.1 Wide string numeric conversion functions
+
@@ -17790,7 +18465,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
float wcstof(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);
long double wcstold(const wchar_t * restrict nptr,
- wchar_t ** restrict endptr);
+ wchar_t ** restrict endptr);
+
The wcstod, wcstof, and wcstold functions convert the initial portion of the wide @@ -17812,14 +18488,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 decimal-point wide character, then an optional binary exponent part as defined in 6.4.4.2;
n-wchar-sequence:
digit
nondigit
n-wchar-sequence digit
- n-wchar-sequence nondigit
+ 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.
@@ -17838,7 +18515,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
sign, the sequence is interpreted as negated.294) 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
+ 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.295) A pointer to the
final wide string is stored in the object pointed to by endptr, provided that endptr is
@@ -17853,7 +18530,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
@@ -17902,7 +18579,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
to the same internal floating value, but if not will round to adjacent values.
-7.24.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions
+
@@ -17922,7 +18599,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
unsigned long long int wcstoull(
const wchar_t * restrict nptr,
wchar_t ** restrict endptr,
- int base);
+ int base);
+
The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
@@ -17976,15 +18654,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.4.2 Wide string copying functions
+
#include <wchar.h>
wchar_t *wcscpy(wchar_t * restrict s1,
- const wchar_t * restrict s2);
+ const wchar_t * restrict s2);
+
The wcscpy function copies the wide string pointed to by s2 (including the terminating
@@ -17994,14 +18673,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wcscpy function returns the value of s1.
-7.24.4.2.2 The wcsncpy function
+
#include <wchar.h>
wchar_t *wcsncpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);
+ size_t n);
+
The wcsncpy function copies not more than n wide characters (those that follow a null
@@ -18020,14 +18700,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
result will not be null-terminated.
-7.24.4.2.3 The wmemcpy function
+
#include <wchar.h>
wchar_t *wmemcpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);
+ size_t n);
+
The wmemcpy function copies n wide characters from the object pointed to by s2 to the
@@ -18041,13 +18722,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-7.24.4.2.4 The wmemmove function
+
#include <wchar.h>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
- size_t n);
+ size_t n);
+
The wmemmove function copies n wide characters from the object pointed to by s2 to @@ -18059,15 +18741,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wmemmove function returns the value of s1.
-7.24.4.3 Wide string concatenation functions
+
#include <wchar.h>
wchar_t *wcscat(wchar_t * restrict s1,
- const wchar_t * restrict s2);
+ const wchar_t * restrict s2);
+
The wcscat function appends a copy of the wide string pointed to by s2 (including the @@ -18077,14 +18760,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wcscat function returns the value of s1.
-7.24.4.3.2 The wcsncat function
+
#include <wchar.h>
wchar_t *wcsncat(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);
+ size_t n);
+
The wcsncat function appends not more than n wide characters (a null wide character
@@ -18102,18 +18786,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
wcslen(s1)+n+1.
-7.24.4.4 Wide string comparison functions
+
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.
-7.24.4.4.1 The wcscmp function
+
#include <wchar.h>
- int wcscmp(const wchar_t *s1, const wchar_t *s2);
+ int wcscmp(const wchar_t *s1, const wchar_t *s2);
+
The wcscmp function compares the wide string pointed to by s1 to the wide string
@@ -18124,12 +18809,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
wide string pointed to by s2.
-7.24.4.4.2 The wcscoll function
+
#include <wchar.h>
- int wcscoll(const wchar_t *s1, const wchar_t *s2);
+ int wcscoll(const wchar_t *s1, const wchar_t *s2);
+
The wcscoll function compares the wide string pointed to by s1 to the wide string
@@ -18145,13 +18831,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
wide string pointed to by s2 when both are interpreted as appropriate to the current
locale.
-7.24.4.4.3 The wcsncmp function
+
#include <wchar.h>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
- size_t n);
+ size_t n);
+
The wcsncmp function compares not more than n wide characters (those that follow a
@@ -18163,14 +18850,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.4.4.4 The wcsxfrm function
+
#include <wchar.h>
size_t wcsxfrm(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);
+ size_t n);
+
The wcsxfrm function transforms the wide string pointed to by s2 and places the @@ -18190,16 +18878,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 transformation of the wide string pointed to by s:
- 1 + wcsxfrm(NULL, s, 0)+ 1 + wcsxfrm(NULL, s, 0) + -
#include <wchar.h>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
- size_t n);
+ size_t n);
+
The wmemcmp function compares the first n wide characters of the object pointed to by
@@ -18210,14 +18900,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
-7.24.4.5 Wide string search functions
+
#include <wchar.h>
- wchar_t *wcschr(const wchar_t *s, wchar_t c);
+ wchar_t *wcschr(const wchar_t *s, wchar_t c);
+
The wcschr function locates the first occurrence of c in the wide string pointed to by s.
@@ -18227,12 +18918,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.4.5.2 The wcscspn function
+
#include <wchar.h>
- size_t wcscspn(const wchar_t *s1, const wchar_t *s2);
+ size_t wcscspn(const wchar_t *s1, const wchar_t *s2);
+
The wcscspn function computes the length of the maximum initial segment of the wide @@ -18243,12 +18935,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wcscspn function returns the length of the segment.
-7.24.4.5.3 The wcspbrk function
+
#include <wchar.h>
- wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);
+ wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);
+
The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of
@@ -18258,12 +18951,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.4.5.4 The wcsrchr function
+
#include <wchar.h>
- wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
+ wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
+
The wcsrchr function locates the last occurrence of c in the wide string pointed to by
@@ -18273,12 +18967,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wcsrchr function returns a pointer to the wide character, or a null pointer if c does
not occur in the wide string.
-7.24.4.5.5 The wcsspn function
+
#include <wchar.h>
- size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
+ size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
+
The wcsspn function computes the length of the maximum initial segment of the wide
@@ -18289,12 +18984,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wcsspn function returns the length of the segment.
-7.24.4.5.6 The wcsstr function
+
#include <wchar.h>
- wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);
+ wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);
+
The wcsstr function locates the first occurrence in the wide string pointed to by s1 of
@@ -18306,14 +19002,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
wide string is not found. If s2 points to a wide string with zero length, the function
returns s1.
-7.24.4.5.7 The wcstok function
+
#include <wchar.h>
wchar_t *wcstok(wchar_t * restrict s1,
const wchar_t * restrict s2,
- wchar_t ** restrict ptr);
+ wchar_t ** restrict ptr);
+
A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into
@@ -18360,16 +19057,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+ t = wcstok(NULL, L"?", &ptr1); // t is a null pointer
+
-7.24.4.5.8 The wmemchr function
+
#include <wchar.h>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
- size_t n);
+ size_t n);
+
The wmemchr function locates the first occurrence of c in the initial n wide characters of
@@ -18380,14 +19079,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the wide character does not occur in the object.
-7.24.4.6 Miscellaneous functions
+
#include <wchar.h>
- size_t wcslen(const wchar_t *s);
+ size_t wcslen(const wchar_t *s);
+
The wcslen function computes the length of the wide string pointed to by s.
@@ -18396,12 +19096,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wcslen function returns the number of wide characters that precede the terminating
null wide character.
-7.24.4.6.2 The wmemset function
+
#include <wchar.h>
- wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
+ wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
+
The wmemset function copies the value of c into each of the first n wide characters of @@ -18410,9 +19111,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The wmemset function returns the value of s.
-7.24.5 Wide character time conversion functions
+
@@ -18421,7 +19122,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size_t wcsftime(wchar_t * restrict s,
size_t maxsize,
const wchar_t * restrict format,
- const struct tm * restrict timeptr);
+ const struct tm * restrict timeptr);
+
The wcsftime function is equivalent to the strftime function, except that:
@@ -18442,7 +19144,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
wide character. Otherwise, zero is returned and the contents of the array are
indeterminate.
-7.24.6 Extended multibyte/wide character conversion utilities
+
The header <wchar.h> declares an extended set of functions useful for conversion
between multibyte characters and wide characters.
@@ -18479,15 +19181,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character string.
-7.24.6.1 Single-byte/wide character conversion functions
+
#include <stdio.h>
#include <wchar.h>
- wint_t btowc(int c);
+ wint_t btowc(int c);
+
The btowc function determines whether c constitutes a valid single-byte character in the
@@ -18498,13 +19201,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
does not constitute a valid single-byte character in the initial shift state. Otherwise, it
returns the wide character representation of that character.
-7.24.6.1.2 The wctob function
+
#include <stdio.h>
#include <wchar.h>
- int wctob(wint_t c);
+ int wctob(wint_t c);
+
The wctob function determines whether c corresponds to a member of the extended
@@ -18516,14 +19220,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.
-7.24.6.2 Conversion state functions
+
#include <wchar.h>
- int mbsinit(const mbstate_t *ps);
+ int mbsinit(const mbstate_t *ps);
+
If ps is not a null pointer, the mbsinit function determines whether the pointed-to
@@ -18534,7 +19239,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The mbsinit function returns nonzero if ps is a null pointer or if the pointed-to object
describes an initial conversion state; otherwise, it returns zero.
-7.24.6.3 Restartable multibyte/wide character conversion functions
+
These functions differ from the corresponding multibyte character functions of 7.20.7
(mblen, mbtowc, and wctomb) in that they have an extra parameter, ps, of type
@@ -18547,19 +19252,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Also unlike their corresponding functions, the return value does not represent whether the
encoding is state-dependent.
-7.24.6.3.1 The mbrlen function
+
#include <wchar.h>
size_t mbrlen(const char * restrict s,
size_t n,
- mbstate_t * restrict ps);
+ mbstate_t * restrict ps);
+
The mbrlen function is equivalent to the call:
- mbrtowc(NULL, s, n, ps != NULL ? ps : &internal)+ 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.
Forward references: the mbrtowc function (7.24.6.3.2).
-7.24.6.3.2 The mbrtowc function
+
@@ -18577,12 +19284,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size_t mbrtowc(wchar_t * restrict pwc,
const char * restrict s,
size_t n,
- mbstate_t * restrict ps);
+ mbstate_t * restrict ps);
+
If s is a null pointer, the mbrtowc function is equivalent to the call:
- mbrtowc(NULL, "", 1, ps)+ mbrtowc(NULL, "", 1, ps) + In this case, the values of the parameters pwc and n are ignored.
If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with @@ -18596,23 +19305,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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 -
+
+ of bytes that complete the multibyte character. +
+ stored).300) +
#include <wchar.h>
size_t wcrtomb(char * restrict s,
wchar_t wc,
- mbstate_t * restrict ps);
+ mbstate_t * restrict ps);
+
If s is a null pointer, the wcrtomb function is equivalent to the call
- wcrtomb(buf, L'\0', ps)+ wcrtomb(buf, L'\0', ps) + where buf is an internal buffer.
If s is not a null pointer, the wcrtomb function determines the number of bytes needed
@@ -18648,7 +19356,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
the function stores the value of the macro EILSEQ in errno and returns
(size_t)(-1); the conversion state is unspecified.
-7.24.6.4 Restartable multibyte/wide string conversion functions
+
These functions differ from the corresponding multibyte string functions of 7.20.8
(mbstowcs and wcstombs) in that they have an extra parameter, ps, of type pointer to
@@ -18664,7 +19372,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
to reflect the amount of the source processed by that invocation.
-7.24.6.4.1 The mbsrtowcs function
+
@@ -18672,7 +19380,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size_t mbsrtowcs(wchar_t * restrict dst,
const char ** restrict src,
size_t len,
- mbstate_t * restrict ps);
+ mbstate_t * restrict ps);
+
The mbsrtowcs function converts a sequence of multibyte characters that begins in the @@ -18707,7 +19416,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
301) Thus, the value of len is ignored if dst is a null pointer.
-7.24.6.4.2 The wcsrtombs function
+
@@ -18715,7 +19424,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src,
size_t len,
- mbstate_t * restrict ps);
+ mbstate_t * restrict ps);
+
The wcsrtombs function converts a sequence of wide characters from the array
@@ -18752,22 +19462,25 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
include those necessary to reach the initial shift state immediately before the null byte.
-7.25 Wide character classification and mapping utilities
+
The header <wctype.h> declares three data types, one macro, and many functions.303)
The types declared are
- wint_t+ wint_t + described in 7.24.1;
- wctrans_t+ wctrans_t + which is a scalar type that can hold values which represent locale-specific character mappings; and
- wctype_t+ wctype_t + which is a scalar type that can hold values which represent locale-specific character classifications.
@@ -18797,7 +19510,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
303) See ''future library directions'' (7.26.13).
-7.25.2 Wide character classification utilities
+
The header <wctype.h> declares several functions useful for classifying wide
characters.
@@ -18807,7 +19520,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
term control wide character refers to a member of a locale-specific set of wide characters
that are not printing wide characters.
-7.25.2.1 Wide character classification functions
+
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.
@@ -18826,23 +19539,25 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
&& iswspace(wc) is true, but not both.
-7.25.2.1.1 The iswalnum function
+
#include <wctype.h>
- int iswalnum(wint_t wc);
+ int iswalnum(wint_t wc);
+
The iswalnum function tests for any wide character for which iswalpha or
iswdigit is true.
-7.25.2.1.2 The iswalpha function
+
#include <wctype.h>
- int iswalpha(wint_t wc);
+ int iswalpha(wint_t wc);
+
The iswalpha function tests for any wide character for which iswupper or
@@ -18857,12 +19572,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
wide characters; all four combinations are possible.
-7.25.2.1.3 The iswblank function
+
#include <wctype.h>
- int iswblank(wint_t wc);
+ int iswblank(wint_t wc);
+
The iswblank function tests for any wide character that is a standard blank wide
@@ -18871,33 +19587,36 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters are the following: space (L' '), and horizontal tab (L'\t'). In the "C"
locale, iswblank returns true only for the standard blank characters.
-7.25.2.1.4 The iswcntrl function
+
#include <wctype.h>
- int iswcntrl(wint_t wc);
+ int iswcntrl(wint_t wc);
+
The iswcntrl function tests for any control wide character.
-7.25.2.1.5 The iswdigit function
+
#include <wctype.h>
- int iswdigit(wint_t wc);
+ int iswdigit(wint_t wc);
+
The iswdigit function tests for any wide character that corresponds to a decimal-digit
character (as defined in 5.2.1).
-7.25.2.1.6 The iswgraph function
+
#include <wctype.h>
- int iswgraph(wint_t wc);
+ int iswgraph(wint_t wc);
+
@@ -18914,46 +19633,50 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters other than ' '.
-
#include <wctype.h>
- int iswlower(wint_t wc);
+ int iswlower(wint_t wc);
+
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.
-7.25.2.1.8 The iswprint function
+
#include <wctype.h>
- int iswprint(wint_t wc);
+ int iswprint(wint_t wc);
+
The iswprint function tests for any printing wide character.
-7.25.2.1.9 The iswpunct function
+
#include <wctype.h>
- int iswpunct(wint_t wc);
+ int iswpunct(wint_t wc);
+
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.306)
-7.25.2.1.10 The iswspace function
+
#include <wctype.h>
- int iswspace(wint_t wc);
+ int iswspace(wint_t wc);
+
@@ -18964,41 +19687,44 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
set of white-space wide characters for which none of iswalnum, iswgraph, or
iswpunct is true.
-
#include <wctype.h>
- int iswupper(wint_t wc);
+ int iswupper(wint_t wc);
+
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.
-7.25.2.1.12 The iswxdigit function
+
#include <wctype.h>
- int iswxdigit(wint_t wc);
+ int iswxdigit(wint_t wc);
+
The iswxdigit function tests for any wide character that corresponds to a
hexadecimal-digit character (as defined in 6.4.4.1).
-7.25.2.2 Extensible wide character classification functions
+
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 (7.25.2.1).
-7.25.2.2.1 The iswctype function
+
#include <wctype.h>
- int iswctype(wint_t wc, wctype_t desc);
+ int iswctype(wint_t wc, wctype_t desc);
+
The iswctype function determines whether the wide character wc has the property @@ -19020,19 +19746,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 iswctype(wc, wctype("punct")) // iswpunct(wc) iswctype(wc, wctype("space")) // iswspace(wc) iswctype(wc, wctype("upper")) // iswupper(wc) - iswctype(wc, wctype("xdigit")) // iswxdigit(wc) + iswctype(wc, wctype("xdigit")) // iswxdigit(wc) +
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 (7.25.2.2.2).
-7.25.2.2.2 The wctype function
+
#include <wctype.h>
- wctype_t wctype(const char *property);
+ wctype_t wctype(const char *property);
+
The wctype function constructs a value with type wctype_t that describes a class of
@@ -19047,18 +19775,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
as the second argument to the iswctype function; otherwise, it returns zero. *
-7.25.3 Wide character case mapping utilities
+
The header <wctype.h> declares several functions useful for mapping wide characters.
-7.25.3.1 Wide character case mapping functions
+
#include <wctype.h>
- wint_t towlower(wint_t wc);
+ wint_t towlower(wint_t wc);
+
The towlower function converts an uppercase letter to a corresponding lowercase letter.
@@ -19070,12 +19799,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters (always the same one for any given locale); otherwise, the argument is
returned unchanged.
-7.25.3.1.2 The towupper function
+
#include <wctype.h>
- wint_t towupper(wint_t wc);
+ wint_t towupper(wint_t wc);
+
The towupper function converts a lowercase letter to a corresponding uppercase letter.
@@ -19087,19 +19817,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters (always the same one for any given locale); otherwise, the argument is
returned unchanged.
-7.25.3.2 Extensible wide character case mapping functions
+
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 (7.25.3.1).
-7.25.3.2.1 The towctrans function
+
#include <wctype.h>
- wint_t towctrans(wint_t wc, wctrans_t desc);
+ wint_t towctrans(wint_t wc, wctrans_t desc);
+
The towctrans function maps the wide character wc using the mapping described by @@ -19110,18 +19841,20 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 mapping function (7.25.3.1) in the comment that follows the expression:
towctrans(wc, wctrans("tolower")) // towlower(wc)
- towctrans(wc, wctrans("toupper")) // towupper(wc)
+ towctrans(wc, wctrans("toupper")) // towupper(wc)
+
The towctrans function returns the mapped value of wc using the mapping described
by desc.
-7.25.3.2.2 The wctrans function
+
#include <wctype.h>
- wctrans_t wctrans(const char *property);
+ wctrans_t wctrans(const char *property);
+
The wctrans function constructs a value with type wctrans_t that describes a
@@ -19136,52 +19869,53 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
as the second argument to the towctrans function; otherwise, it returns zero.
-7.26 Future library directions
+
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.
-7.26.1 Complex arithmetic
+
The function names
cerf cexpm1 clog2
cerfc clog10 clgamma
- cexp2 clog1p ctgamma
+ cexp2 clog1p ctgamma
+
and the same names suffixed with f or l may be added to the declarations in the
<complex.h> header.
-
Function names that begin with either is or to, and a lowercase letter may be added to
the declarations in the <ctype.h> header.
-7.26.3 Errors
+
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.
-7.26.4 Format conversion of integer types
+
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.
-7.26.5 Localization
+
Macros that begin with LC_ and an uppercase letter may be added to the definitions in
the <locale.h> header.
-7.26.6 Signal handling
+
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.
-7.26.7 Boolean type and values
+
The ability to undefine and perhaps then redefine the macros bool, true, and false is
an obsolescent feature.
-7.26.8 Integer types
+
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
@@ -19189,7 +19923,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
<stdint.h> header.
-7.26.9 Input/output
+
Lowercase letters may be added to the conversion specifiers and length modifiers in
fprintf and fscanf. Other characters may be used in extensions.
@@ -19199,17 +19933,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The use of ungetc on a binary stream where the file position indicator is zero prior to
the call is an obsolescent feature.
-7.26.10 General utilities
+
Function names that begin with str and a lowercase letter may be added to the
declarations in the <stdlib.h> header.
-7.26.11 String handling
+
Function names that begin with str, mem, or wcs and a lowercase letter may be added
to the declarations in the <string.h> header.
-7.26.12 Extended multibyte and wide character utilities
+
Function names that begin with wcs and a lowercase letter may be added to the
declarations in the <wchar.h> header.
@@ -19217,31 +19951,33 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Lowercase letters may be added to the conversion specifiers and length modifiers in
fwprintf and fwscanf. Other characters may be used in extensions.
-7.26.13 Wide character classification and mapping utilities
+
Function names that begin with is or to and a lowercase letter may be added to the
declarations in the <wctype.h> header.
-Annex A
+
(informative)
- Language syntax summary
+ Language syntax summary
+
NOTE The notation is described in 6.1.
-
keyword
identifier
constant
string-literal
- punctuator
+ punctuator
+
(6.4) preprocessing-token:
header-name
@@ -19250,9 +19986,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
character-constant
string-literal
punctuator
- each non-white-space character that cannot be one of the above
+ each non-white-space character that cannot be one of the above
+
-
@@ -19265,193 +20002,235 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
default inline struct _Imaginary
do int switch
double long typedef
- else register union
+ else register union
+
-
identifier-nondigit
identifier identifier-nondigit
- identifier digit
+ identifier digit
+
(6.4.2.1) identifier-nondigit:
nondigit
universal-character-name
- other implementation-defined characters
+ 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
+ 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+ 0 1 2 3 4 5 6 7 8 9 + -
\u hex-quad
- \U hex-quad hex-quad
+ \U hex-quad hex-quad
+
(6.4.3) hex-quad:
hexadecimal-digit hexadecimal-digit
- hexadecimal-digit hexadecimal-digit
+ hexadecimal-digit hexadecimal-digit
+
-
integer-constant
floating-constant
enumeration-constant
- character-constant
+ character-constant
+
(6.4.4.1) integer-constant:
decimal-constant integer-suffixopt
octal-constant integer-suffixopt
- hexadecimal-constant integer-suffixopt
+ hexadecimal-constant integer-suffixopt
+
(6.4.4.1) decimal-constant:
nonzero-digit
- decimal-constant digit
+ decimal-constant digit
+
(6.4.4.1) octal-constant:
0
- octal-constant octal-digit
+ octal-constant octal-digit
+
(6.4.4.1) hexadecimal-constant:
hexadecimal-prefix hexadecimal-digit
- hexadecimal-constant hexadecimal-digit
+ hexadecimal-constant hexadecimal-digit
+
(6.4.4.1) hexadecimal-prefix: one of
- 0x 0X+ 0x 0X + (6.4.4.1) nonzero-digit: one of
- 1 2 3 4 5 6 7 8 9+ 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+ 0 1 2 3 4 5 6 7 + (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
+ 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
+ long-long-suffix unsigned-suffixopt
+
(6.4.4.1) unsigned-suffix: one of
- u U+ u U + (6.4.4.1) long-suffix: one of
- l L+ l L + (6.4.4.1) long-long-suffix: one of
- ll LL+ ll LL + (6.4.4.2) floating-constant:
decimal-floating-constant
- hexadecimal-floating-constant
+ hexadecimal-floating-constant
+
(6.4.4.2) decimal-floating-constant:
fractional-constant exponent-partopt floating-suffixopt
- digit-sequence exponent-part 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
+ binary-exponent-part floating-suffixopt
+
(6.4.4.2) fractional-constant:
digit-sequenceopt . digit-sequence
- digit-sequence .
+ digit-sequence .
+
(6.4.4.2) exponent-part:
e signopt digit-sequence
- E signopt digit-sequence
+ E signopt digit-sequence
+
(6.4.4.2) sign: one of
- + -+ + - + (6.4.4.2) digit-sequence:
digit
- digit-sequence digit
+ digit-sequence digit
+
(6.4.4.2) hexadecimal-fractional-constant:
hexadecimal-digit-sequenceopt .
hexadecimal-digit-sequence
- hexadecimal-digit-sequence .
+ hexadecimal-digit-sequence .
+
(6.4.4.2) binary-exponent-part:
p signopt digit-sequence
- P signopt digit-sequence
+ P signopt digit-sequence
+
(6.4.4.2) hexadecimal-digit-sequence:
hexadecimal-digit
- hexadecimal-digit-sequence hexadecimal-digit
+ hexadecimal-digit-sequence hexadecimal-digit
+
(6.4.4.2) floating-suffix: one of
- f l F L+ f l F L + (6.4.4.3) enumeration-constant:
- identifier+ identifier + (6.4.4.4) character-constant:
' c-char-sequence '
- L' c-char-sequence '
+ L' c-char-sequence '
+
(6.4.4.4) c-char-sequence:
c-char
- 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
+ escape-sequence
+
(6.4.4.4) escape-sequence:
simple-escape-sequence
octal-escape-sequence
hexadecimal-escape-sequence
- universal-character-name
+ universal-character-name
+
(6.4.4.4) simple-escape-sequence: one of
\' \" \? \\
- \a \b \f \n \r \t \v
+ \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
+ \ octal-digit octal-digit octal-digit
+
(6.4.4.4) hexadecimal-escape-sequence:
\x hexadecimal-digit
- hexadecimal-escape-sequence hexadecimal-digit
+ hexadecimal-escape-sequence hexadecimal-digit
+
-
" s-char-sequenceopt "
- L" s-char-sequenceopt "
+ L" s-char-sequenceopt "
+
(6.4.5) s-char-sequence:
s-char
- 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
+ escape-sequence
+
-
[ ] ( ) { } . ->
@@ -19460,31 +20239,37 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
? : ; ...
= *= /= %= += -= <<= >>= &= ^= |=
, # ##
- <: :> <% %> %: %:%:
+ <: :> <% %> %: %:%:
+
-
< h-char-sequence >
- " q-char-sequence "
+ " q-char-sequence "
+
(6.4.7) h-char-sequence:
h-char
- 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 >
+ the new-line character and >
+
(6.4.7) q-char-sequence:
q-char
- 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 "
+ the new-line character and "
+
-
@@ -19496,17 +20281,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
pp-number E sign
pp-number p sign
pp-number P sign
- pp-number .
+ pp-number .
+
-
identifier
constant
string-literal
- ( expression )
+ ( expression )
+
(6.5.2) postfix-expression:
primary-expression
@@ -19517,11 +20304,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
- ( type-name ) { initializer-list , }
+ ( type-name ) { initializer-list , }
+
(6.5.2) argument-expression-list:
assignment-expression
- argument-expression-list , assignment-expression
+ argument-expression-list , assignment-expression
+
(6.5.3) unary-expression:
postfix-expression
@@ -19529,101 +20318,123 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-- unary-expression
unary-operator cast-expression
sizeof unary-expression
- sizeof ( type-name )
+ sizeof ( type-name )
+
(6.5.3) unary-operator: one of
- & * + - ~ !+ & * + - ~ ! + (6.5.4) cast-expression:
unary-expression
- ( type-name ) cast-expression
+ ( type-name ) cast-expression
+
(6.5.5) multiplicative-expression:
cast-expression
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
+ additive-expression - multiplicative-expression
+
(6.5.7) shift-expression:
additive-expression
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
+ relational-expression >= shift-expression
+
(6.5.9) equality-expression:
relational-expression
equality-expression == relational-expression
- equality-expression != relational-expression
+ equality-expression != relational-expression
+
(6.5.10) AND-expression:
equality-expression
- AND-expression & equality-expression
+ AND-expression & equality-expression
+
(6.5.11) exclusive-OR-expression:
AND-expression
- exclusive-OR-expression ^ AND-expression
+ exclusive-OR-expression ^ AND-expression
+
(6.5.12) inclusive-OR-expression:
exclusive-OR-expression
- 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
+ logical-AND-expression && inclusive-OR-expression
+
(6.5.14) logical-OR-expression:
logical-AND-expression
- 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
+ logical-OR-expression ? expression : conditional-expression
+
(6.5.16) assignment-expression:
conditional-expression
- unary-expression assignment-operator assignment-expression
+ unary-expression assignment-operator assignment-expression
+
(6.5.16) assignment-operator: one of
- = *= /= %= += -= <<= >>= &= ^= |=+ = *= /= %= += -= <<= >>= &= ^= |= + (6.5.17) expression:
assignment-expression
- expression , assignment-expression
+ expression , assignment-expression
+
(6.6) constant-expression:
- conditional-expression+ conditional-expression + -
- declaration-specifiers init-declarator-listopt ;+ declaration-specifiers init-declarator-listopt ; + (6.7) declaration-specifiers:
storage-class-specifier declaration-specifiersopt
type-specifier declaration-specifiersopt
type-qualifier declaration-specifiersopt
- function-specifier declaration-specifiersopt
+ function-specifier declaration-specifiersopt
+
(6.7) init-declarator-list:
init-declarator
- init-declarator-list , init-declarator
+ init-declarator-list , init-declarator
+
(6.7) init-declarator:
declarator
- declarator = initializer
+ declarator = initializer
+
(6.7.1) storage-class-specifier:
@@ -19631,7 +20442,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
extern
static
auto
- register
+ register
+
(6.7.2) type-specifier:
void
@@ -19647,59 +20459,73 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
_Complex
struct-or-union-specifier *
enum-specifier
- typedef-name
+ typedef-name
+
(6.7.2.1) struct-or-union-specifier:
struct-or-union identifieropt { struct-declaration-list }
- struct-or-union identifier
+ struct-or-union identifier
+
(6.7.2.1) struct-or-union:
struct
- union
+ union
+
(6.7.2.1) struct-declaration-list:
struct-declaration
- struct-declaration-list struct-declaration
+ struct-declaration-list struct-declaration
+
(6.7.2.1) struct-declaration:
- specifier-qualifier-list struct-declarator-list ;+ specifier-qualifier-list struct-declarator-list ; + (6.7.2.1) specifier-qualifier-list:
type-specifier specifier-qualifier-listopt
- type-qualifier specifier-qualifier-listopt
+ type-qualifier specifier-qualifier-listopt
+
(6.7.2.1) struct-declarator-list:
struct-declarator
- struct-declarator-list , struct-declarator
+ struct-declarator-list , struct-declarator
+
(6.7.2.1) struct-declarator:
declarator
- declaratoropt : constant-expression
+ declaratoropt : constant-expression
+
(6.7.2.2) enum-specifier:
enum identifieropt { enumerator-list }
enum identifieropt { enumerator-list , }
- enum identifier
+ enum identifier
+
(6.7.2.2) enumerator-list:
enumerator
- enumerator-list , enumerator
+ enumerator-list , enumerator
+
(6.7.2.2) enumerator:
enumeration-constant
- enumeration-constant = constant-expression
+ enumeration-constant = constant-expression
+
(6.7.3) type-qualifier:
const
restrict
- volatile
+ volatile
+
(6.7.4) function-specifier:
- inline+ inline + (6.7.5) declarator:
- pointeropt direct-declarator+ pointeropt direct-declarator + (6.7.5) direct-declarator:
identifier
@@ -19709,39 +20535,48 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
direct-declarator [ type-qualifier-list static assignment-expression ]
direct-declarator [ type-qualifier-listopt * ]
direct-declarator ( parameter-type-list )
- direct-declarator ( identifier-listopt )
+ direct-declarator ( identifier-listopt )
+
(6.7.5) pointer:
* type-qualifier-listopt
- * type-qualifier-listopt pointer
+ * type-qualifier-listopt pointer
+
(6.7.5) type-qualifier-list:
type-qualifier
- type-qualifier-list type-qualifier
+ type-qualifier-list type-qualifier
+
(6.7.5) parameter-type-list:
parameter-list
- parameter-list , ...
+ parameter-list , ...
+
(6.7.5) parameter-list:
parameter-declaration
- parameter-list , parameter-declaration
+ parameter-list , parameter-declaration
+
(6.7.5) parameter-declaration:
declaration-specifiers declarator
- declaration-specifiers abstract-declaratoropt
+ declaration-specifiers abstract-declaratoropt
+
(6.7.5) identifier-list:
identifier
- identifier-list , identifier
+ identifier-list , identifier
+
(6.7.6) type-name:
- specifier-qualifier-list abstract-declaratoropt+ specifier-qualifier-list abstract-declaratoropt + (6.7.6) abstract-declarator:
pointer
- pointeropt direct-abstract-declarator
+ pointeropt direct-abstract-declarator
+
(6.7.6) direct-abstract-declarator:
( abstract-declarator )
@@ -19752,33 +20587,40 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
direct-abstract-declaratoropt [ type-qualifier-list static
assignment-expression ]
direct-abstract-declaratoropt [ * ]
- direct-abstract-declaratoropt ( parameter-type-listopt )
+ direct-abstract-declaratoropt ( parameter-type-listopt )
+
(6.7.7) typedef-name:
- identifier+ identifier + (6.7.8) initializer:
assignment-expression
{ initializer-list }
- { initializer-list , }
+ { initializer-list , }
+
(6.7.8) initializer-list:
designationopt initializer
- initializer-list , designationopt initializer
+ initializer-list , designationopt initializer
+
(6.7.8) designation:
- designator-list =+ designator-list = + (6.7.8) designator-list:
designator
- designator-list designator
+ designator-list designator
+
(6.7.8) designator:
[ constant-expression ]
- . identifier
+ . identifier
+
-
labeled-statement
@@ -19786,98 +20628,120 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
expression-statement
selection-statement
iteration-statement
- jump-statement
+ jump-statement
+
(6.8.1) labeled-statement:
identifier : statement
case constant-expression : statement
- default : statement
+ default : statement
+
(6.8.2) compound-statement:
- { block-item-listopt }
+ { block-item-listopt }
+
(6.8.2) block-item-list:
block-item
- block-item-list block-item
+ block-item-list block-item
+
(6.8.2) block-item:
declaration
- statement
+ statement
+
(6.8.3) expression-statement:
- expressionopt ;+ expressionopt ; + (6.8.4) selection-statement:
if ( expression ) statement
if ( expression ) statement else statement
- switch ( expression ) 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
+ for ( declaration expressionopt ; expressionopt ) statement
+
(6.8.6) jump-statement:
goto identifier ;
continue ;
break ;
- return expressionopt ;
+ return expressionopt ;
+
-
external-declaration
- translation-unit external-declaration
+ translation-unit external-declaration
+
(6.9) external-declaration:
function-definition
- declaration
+ declaration
+
(6.9.1) function-definition:
- declaration-specifiers declarator declaration-listopt compound-statement+ declaration-specifiers declarator declaration-listopt compound-statement + (6.9.1) declaration-list:
declaration
- declaration-list declaration
+ declaration-list declaration
+
-- groupopt+ groupopt + (6.10) group:
group-part
- group group-part
+ group group-part
+
(6.10) group-part:
if-section
control-line
text-line
- # non-directive
+ # non-directive
+
(6.10) if-section:
- if-group elif-groupsopt else-groupopt endif-line+ 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
+ # ifndef identifier new-line groupopt
+
(6.10) elif-groups:
elif-group
- elif-groups elif-group
+ elif-groups elif-group
+
(6.10) elif-group:
- # elif constant-expression new-line groupopt+ # elif constant-expression new-line groupopt + (6.10) else-group:
- # else new-line groupopt+ # else new-line groupopt + (6.10) endif-line:
- # endif new-line+ # endif new-line + (6.10) control-line:
# include pp-tokens new-line
@@ -19891,40 +20755,49 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
# line pp-tokens new-line
# error pp-tokensopt new-line
# pragma pp-tokensopt new-line
- # new-line
+ # new-line
+
(6.10) text-line:
- pp-tokensopt new-line+ pp-tokensopt new-line + (6.10) non-directive:
- pp-tokens new-line+ pp-tokens new-line + (6.10) lparen:
- a ( character not immediately preceded by white-space+ a ( character not immediately preceded by white-space + (6.10) replacement-list:
- pp-tokensopt+ pp-tokensopt + (6.10) pp-tokens:
preprocessing-token
- pp-tokens preprocessing-token
+ pp-tokens preprocessing-token
+
(6.10) new-line:
- the new-line character+ the new-line character + -
(informative)
- Library summary
+ Library summary
+
-
NDEBUG
- void assert(scalar expression);
+ void assert(scalar expression);
+
-
@@ -19997,9 +20870,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ long double creall(long double complex z);
+
-
int isalnum(int c);
int isalpha(int c);
@@ -20014,13 +20888,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int isupper(int c);
int isxdigit(int c);
int tolower(int c);
- int toupper(int c);
+ int toupper(int c);
+
-- EDOM EILSEQ ERANGE errno+ EDOM EILSEQ ERANGE errno + -
fenv_t FE_OVERFLOW FE_TOWARDZERO
@@ -20040,9 +20916,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
int fegetenv(fenv_t *envp);
int feholdexcept(fenv_t *envp);
int fesetenv(const fenv_t *envp);
- int feupdateenv(const fenv_t *envp);
+ int feupdateenv(const fenv_t *envp);
+
-
FLT_ROUNDS DBL_MIN_EXP FLT_MAX
FLT_EVAL_METHOD LDBL_MIN_EXP DBL_MAX
@@ -20054,9 +20931,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
FLT_DIG LDBL_MAX_EXP DBL_MIN
DBL_DIG FLT_MAX_10_EXP LDBL_MIN
LDBL_DIG DBL_MAX_10_EXP
- FLT_MIN_EXP LDBL_MAX_10_EXP
+ FLT_MIN_EXP LDBL_MAX_10_EXP
+
-
imaxdiv_t
@@ -20080,30 +20958,34 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ wchar_t ** restrict endptr, int base);
+
-
and bitor not_eq xor
and_eq compl or xor_eq
- bitand not or_eq
+ bitand not or_eq
+
-
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
+ CHAR_MIN USHRT_MAX LONG_MAX
+
-
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);
+ struct lconv *localeconv(void);
+
-
jmp_buf
int setjmp(jmp_buf env);
- void longjmp(jmp_buf env, int val);
+ void longjmp(jmp_buf env, int val);
+
-
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);
+ int raise(int sig);
+
-
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);
+ void va_start(va_list ap, parmN);
+
-
bool
true
false
- __bool_true_false_are_defined
+ __bool_true_false_are_defined
+
-
ptrdiff_t size_t wchar_t NULL
- offsetof(type, member-designator)
+ offsetof(type, member-designator)
+
-
intN_t INT_LEASTN_MIN PTRDIFF_MAX
uintN_t INT_LEASTN_MAX SIG_ATOMIC_MIN
@@ -20353,9 +21241,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+ UINTN_MAX PTRDIFF_MIN
+
-
@@ -20432,9 +21321,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
void clearerr(FILE *stream);
int feof(FILE *stream);
int ferror(FILE *stream);
- void perror(const char *s);
+ void perror(const char *s);
+
-
@@ -20492,9 +21382,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ const wchar_t * restrict pwcs, size_t n);
+
-
size_t
@@ -20527,9 +21418,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
const char * restrict s2);
void *memset(void *s, int c, size_t n);
char *strerror(int errnum);
- size_t strlen(const char *s);
+ size_t strlen(const char *s);
+
-
acos sqrt fmod nextafter
asin fabs frexp nexttoward
@@ -20545,9 +21437,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
tanh floor logb cimag
exp fma lrint conj
log fmax lround cproj
- pow fmin nearbyint creal
+ pow fmin nearbyint creal
+
-
NULL size_t time_t
@@ -20563,9 +21456,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
- const struct tm * restrict timeptr);
+ const struct tm * restrict timeptr);
+
-
@@ -20671,9 +21565,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
mbstate_t * restrict ps);
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src, size_t len,
- mbstate_t * restrict ps);
+ mbstate_t * restrict ps);
+
-
@@ -20695,13 +21590,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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);
+ wctrans_t wctrans(const char *property);
+
-
(informative)
- Sequence points
+ Sequence points
+
The following are the sequence points described in 5.1.2.3:
(normative)
- Universal character names for identifiers
+ Universal character names for identifiers
+
This clause lists the hexadecimal code values that are valid in universal character names
in identifiers.
@@ -20735,65 +21633,80 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 sets. Latin: 00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217,
- 0250-02A8, 1E00-1E9B, 1EA0-1EF9, 207F+ 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
+ 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+ 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+ 05F0-05F2 + Arabic: 0621-063A, 0640-0652, 0670-06B7, 06BA-06BE, 06C0-06CE,
- 06D0-06DC, 06E5-06E8, 06EA-06ED+ 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
+ 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
+ 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
+ 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,
- 0B5C-0B5D, 0B5F-0B61
+ 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
+ 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+ 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
+ 0CE0-0CE1
+
Malayalam: 0D02-0D03, 0D05-0D0C, 0D0E-0D10, 0D12-0D28, 0D2A-0D39,
- 0D3E-0D43, 0D46-0D48, 0D4A-0D4D, 0D60-0D61+ 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
+ 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
+ 0FB1-0FB7, 0FB9
+
Georgian: 10A0-10C5, 10D0-10F6
Hiragana: 3041-3093, 309B-309C
Katakana: 30A1-30F6, 30FB-30FC
@@ -20803,19 +21716,22 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+ 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
+ 2133-2138, 2160-2182, 3005-3007, 3021-3029
+
-
(informative)
- Implementation limits
+
#define FLT_EVAL_METHOD
- #define FLT_ROUNDS
+ #define FLT_ROUNDS
+
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:
@@ -20877,14 +21795,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#define LDBL_MAX_10_EXP +37
#define LDBL_MAX_EXP
#define LDBL_MIN_10_EXP -37
- #define LDBL_MIN_EXP
+ #define LDBL_MIN_EXP
+
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
+ #define LDBL_MAX 1E+37
+
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:
@@ -20894,14 +21814,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
#define FLT_EPSILON 1E-5
#define FLT_MIN 1E-37
#define LDBL_EPSILON 1E-9
- #define LDBL_MIN 1E-37
+ #define LDBL_MIN 1E-37
+
-
(normative)
- IEC 60559 floating-point arithmetic
+ IEC 60559 floating-point arithmetic
+
-
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
@@ -20915,7 +21837,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
a binding between the C language and IEC 60559 is indicated, the IEC 60559-specified
behavior is adopted by reference, unless stated otherwise.
-F.2 Types
+
The C floating types match the IEC 60559 formats as follows:
The long double type should match an IEC 60559 extended format.
@@ -20943,7 +21865,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
all double values.
-F.2.1 Infinities, signed zeros, and NaNs
+
This specification does not define the behavior of signaling NaNs.309) It generally uses
the term NaN to denote quiet NaNs. The NAN and INFINITY macros and the nan
@@ -20954,7 +21876,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
sufficient for closure of the arithmetic.
-F.3 Operators and functions
+
C operators and functions provide IEC 60559 required and recommended facilities as
listed below.
@@ -21032,7 +21954,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
macros defined in 7.12.3 do not distinguish signaling from quiet NaNs).
-F.4 Floating to integer conversion
+
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
@@ -21048,7 +21970,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
<math.h>.
-F.5 Binary-decimal conversion
+
Conversion from the widest supported IEC 60559 format to decimal with
DECIMAL_DIG digits and back is the identity function.311)
@@ -21076,18 +21998,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
DBL_DIG are 18 and 15, respectively, for these formats.)
-F.6 Contracted expressions
+
A contracted expression 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 +
A contracted expression should raise floating-point exceptions in a manner generally
consistent with the basic arithmetic operations. A contracted expression should deliver
the same value as its uncontracted counterpart, else should be correctly rounded (once).
-F.7 Floating-point environment
+
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 @@ -21098,7 +22020,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
312) This specification does not require dynamic rounding precision nor trap enablement modes.
-F.7.1 Environment management
+
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
@@ -21112,7 +22034,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
which allows certain optimizations (see F.8).
-F.7.2 Translation
+
During translation the IEC 60559 default modes are in effect:
The implementation should produce a diagnostic message for each translation-time
@@ -21138,7 +22060,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
strtod, provide execution-time conversion of numeric strings.
-F.7.3 Execution
+
At program startup the floating-point environment is initialized as prescribed by IEC 60559: @@ -21150,7 +22072,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
An arithmetic constant expression of floating type, other than one in an initializer for an object that has static storage duration, is evaluated (as if) during execution; thus, it is @@ -21170,7 +22092,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 float y = 0.0/0.0; // raises an exception double z = 0.0/0.0; // raises an exception /* ... */ - } + } + 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 @@ -21186,10 +22109,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 efficiency of translation-time evaluation through static initialization, such as
- const static double one_third = 1.0/3.0;+ const static double one_third = 1.0/3.0; + -
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 @@ -21211,7 +22135,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 float y = 1.1e75f; // may raise exceptions long double z = 1.1e75; // does not raise exceptions /* ... */ - } + } + 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 @@ -21231,11 +22156,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 For example, the automatic initialization
- double_t x = 1.1e75;+ double_t x = 1.1e75; + could be done at translation time, regardless of the expression evaluation method. -
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
@@ -21247,12 +22173,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
''inexact'', or ''underflow'' and ''inexact''), then ''overflow'' or ''underflow'' is raised
before ''inexact''.
-F.8 Optimization
+
This section identifies code transformations that might subvert IEC 60559-specified
behavior, and others that do not.
-F.8.1 Global transformations
+
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 @@ -21270,7 +22196,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 /* ... */ 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 @@ -21283,54 +22210,66 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 the preceding loop could be treated as
- if (0 < n) x + 1;+ if (0 < n) x + 1; + -
x / 2 <-> 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.
+ and others that round perfectly.
+
1 * x and x / 1 -> x The expressions 1 * x, x / 1, and x are equivalent
- (on IEC 60559 machines, among others).317)+ (on IEC 60559 machines, among others).317) + x / x -> 1.0 The expressions x / x and 1.0 are not equivalent if x
- can be zero, infinite, or NaN.+ 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).+ 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).318)
+ default rounding direction).318)
+
x - x -> 0.0 The expressions x - x and 0.0 are not equivalent if
- x is a NaN or infinite.+ x is a NaN or infinite. + 0 * x -> 0.0 The expressions 0 * x and 0.0 are not equivalent if
- x is a NaN, infinite, or -0.+ 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.
+ 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
+ implementation can replace x - 0 by x, even if x
+
- might be zero.+ 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).
+ (unless rounding is downward).
+
317) Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
@@ -21340,15 +22279,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Examples include:
- 1/(1/ (+-) (inf)) is (+-) (inf)
+ 1/(1/ (+-) (inf)) is (+-) (inf)
+
and
- conj(csqrt(z)) is csqrt(conj(z)),
+ conj(csqrt(z)) is csqrt(conj(z)),
+
for complex z.
-F.8.3 Relational operators
+
x != x -> false The statement x != x is true if x is a NaN. x == x -> true The statement x == x is false if x is a NaN. @@ -21360,7 +22301,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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''. + 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.
@@ -21370,21 +22312,24 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 if (a < b) f(); else - g(); + g(); + is not equivalent to
// calls f and raises ''invalid'' if a and b are unordered
if (a >= b)
g();
else
- f();
+ f();
+
nor to
// calls f without raising ''invalid'' if a and b are unordered
if (isgreaterequal(a,b))
g();
else
- f();
+ f();
+
nor, unless the state of the FENV_ACCESS pragma is ''off'', to
@@ -21392,16 +22337,18 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
if (isless(a,b))
f();
else
- g();
+ g();
+
but is equivalent to
if (!(a < b))
g();
else
- f();
+ f();
+
-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.7.4 @@ -21416,7 +22363,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
319) 0 - 0 yields -0 instead of +0 just when the rounding direction is downward.
-F.9 Mathematics
+
This subclause contains specifications of <math.h> facilities that are particularly suited for IEC 60559 implementations. @@ -21465,7 +22412,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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 +
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
@@ -21479,9 +22426,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
avoiding them would be too costly.
-F.9.1 Trigonometric functions
+
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.
-F.9.3.6 The ldexp functions
+
On a binary system, ldexp(x, exp) is equivalent to scalbn(x, exp).
-F.9.3.7 The log functions
+
sqrt is fully specified as a basic arithmetic operation in IEC 60559.
-F.9.5 Error and gamma functions
+
See the sample implementation for ceil in F.9.6.1.
-F.9.6.3 The nearbyint functions
+
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 @@ -21874,12 +22824,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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.9.6.5 The lrint and llrint functions
+
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
@@ -21889,7 +22839,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
exception.
-F.9.6.6 The round functions
+
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.9.6.8 The trunc functions
+
The trunc functions use IEC 60559 rounding toward zero (regardless of the current rounding direction). @@ -21934,9 +22885,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The remainder functions are fully specified as a basic arithmetic operation in
IEC 60559.
-F.9.7.3 The remquo functions
+
The remquo functions follow the specifications for the remainder functions. They
have no further specifications special to IEC 60559 implementations.
-F.9.8 Manipulation functions
+
copysign is specified in the Appendix to IEC 60559.
-F.9.8.2 The nan functions
+
All IEC 60559 implementations support quiet NaNs, in all floating formats.
-F.9.8.3 The nextafter functions
+
No additional requirements beyond those on nextafter.
-F.9.9 Maximum, minimum, and positive difference functions
+
No additional requirements.
-F.9.9.2 The fmax functions
+
If just one argument is a NaN, the fmax functions return the other argument (if both arguments are NaNs, the functions return a NaN). @@ -22006,20 +22958,21 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The body of the fmax function might be323)
{ return (isgreaterequal(x, y) ||
- isnan(y)) ? x : y; }
+ isnan(y)) ? x : y; }
+
323) 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.
-F.9.9.3 The fmin functions
+
The fmin functions are analogous to the fmax functions (see F.9.9.2).
-F.9.10 Floating multiply-add
+
(informative)
- IEC 60559-compatible complex arithmetic
+ IEC 60559-compatible complex arithmetic
+
-
This annex supplements annex F to specify complex arithmetic for compatibility with
IEC 60559 real floating-point arithmetic. Although these specifications have been
@@ -22050,7 +23004,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
recommended practice. An implementation that defines
__STDC_IEC_559_COMPLEX__ should conform to the specifications in this annex.
-G.2 Types
+
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 @@ -22069,7 +23023,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
The imaginary type domain comprises the imaginary types.
-G.3 Conventions
+
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
@@ -22077,14 +23031,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
a zero if each of its parts is a zero.
-G.4 Conversions
+
Conversions among imaginary types follow rules analogous to those for real floating
types.
-G.4.2 Real and imaginary
+
When a value of imaginary type is converted to a real type other than _Bool,324) the result is a positive zero. @@ -22096,7 +23050,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
324) See 6.3.1.2.
-G.4.3 Imaginary and complex
+
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
@@ -22106,7 +23060,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
The following subclauses supplement 6.5 in order to specify the type of the result for an
operation with an imaginary operand.
@@ -22123,7 +23077,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
-G.5.1 Multiplicative operators
+
If one operand has real type and the other operand has imaginary type, then the result has @@ -22133,31 +23087,39 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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+ * u iv u + iv +
- x xu i(xv) (xu) + i(xv)+ x xu i(xv) (xu) + i(xv) +
- iy i(yu) -yv (-yv) + i(yu)+ iy i(yu) -yv (-yv) + i(yu) +
- x + iy (xu) + i(yu) (-yv) + i(xv)+ x + iy (xu) + i(yu) (-yv) + i(xv) + 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+ / u iv +
- x x/u i(-x/v)+ x x/u i(-x/v) +
- iy i(y/u) y/v+ iy i(y/u) y/v +
- x + iy (x/u) + i(y/u) (y/v) + i(-x/v)+ x + iy (x/u) + i(y/u) (y/v) + i(-x/v) + The * and / operators satisfy the following infinity properties for all real, imaginary, and complex operands:325)
If both operands have imaginary type, then the result has imaginary type. (If one operand @@ -22304,29 +23268,36 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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+ + or - u iv u + iv +
- x x(+-)u x (+-) iv (x (+-) u) (+-) iv+ x x(+-)u x (+-) iv (x (+-) u) (+-) iv +
- iy (+-)u + iy i(y (+-) v) (+-)u + i(y (+-) v)+ iy (+-)u + iy i(y (+-) v) (+-)u + i(y (+-) v) +
- x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v)+ x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v) + -
The macros
- imaginary+ imaginary + and
- _Imaginary_I+ _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+ 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. @@ -22355,7 +23326,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
cabs(x + iy) = hypot(x, y)
- carg(x + iy) = atan2(y, x)
+ carg(x + iy) = atan2(y, x)
+
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):
@@ -22364,7 +23336,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
catan(z) = -i catanh(iz)
ccos(z) = ccosh(iz)
csin(z) = -i csinh(iz)
- ctan(z) = -i ctanh(iz)
+ ctan(z) = -i ctanh(iz)
+
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
@@ -22385,9 +23358,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
other part is a NaN.
-G.6.1 Trigonometric functions
+
The cpow functions raise floating-point exceptions if appropriate for the calculation of
the parts of the result, and may raise spurious exceptions.327)
@@ -22606,7 +23579,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
implementations that treat special cases more carefully.
-G.6.4.2 The csqrt functions
+
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,
@@ -22652,31 +23625,33 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
asin(iy) = i asinh(y)
atan(iy) = i atanh(y)
asinh(iy) = i asin(y)
- atanh(iy) = i atan(y)
+ atanh(iy) = i atan(y)
+
-Annex H
+
(informative)
- Language independent arithmetic
+ Language independent arithmetic
+
-
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
+
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
+
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
+
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 @@ -22689,14 +23664,15 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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+ ULLONG_MAX + minint INT_MIN, LONG_MIN, LLONG_MIN
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.
-H.2.2.1 Integer operations
+
The integer operations on integer types are the following:
addI x + y
@@ -22714,7 +23690,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
geqI x >= y
where x and y are expressions of the same integer type.
-H.2.3 Floating-point types
+
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
@@ -22723,7 +23699,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
operations (see annex F) along with IEC 60559 status flags and traps has LIA-1
conformant types.
-H.2.3.1 Floating-point parameters
+
The parameters for a floating point data type can be accessed by the following:
r FLT_RADIX
@@ -22738,7 +23714,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
epsilon FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON
rnd_style FLT_ROUNDS
-H.2.3.2 Floating-point operations
+
The floating-point operations on floating-point types are the following: addF x + y @@ -22750,7 +23726,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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)+ 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 @@ -22762,7 +23739,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 where x and y are expressions of the same floating point type, n is of type int, and li is of type long int. -
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.
@@ -22775,17 +23752,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
+ (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
+ (unsigned long long int)x
+
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
@@ -22812,14 +23791,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
implementation uses round-to-nearest.
-H.3 Notification
+
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
+
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-
@@ -22839,7 +23818,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
C's <fenv.h> status flags are compatible with the LIA-1 indicators.
@@ -22864,7 +23843,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
This documentation makes that distinction because <fenv.h> covers only the floating-
point indicators.
-H.3.1.2 Traps
+
C is compatible with LIA-1's trap requirements for arithmetic operations, but not for
math library functions (which are not permitted to generate any externally visible
@@ -22882,11 +23861,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
resume, at the programmer's option.
-Annex I
+
(informative)
- Common warnings
+ Common warnings
+
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.
@@ -22926,15 +23906,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
(informative)
- Portability issues
+ Portability issues
+
This annex collects some information about portability that appears in this International
Standard.
-The following are unspecified:
The behavior is undefined in the following circumstances:
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
+
The following characteristics of a hosted environment are locale-specific and are required to be documented by the implementation: @@ -23815,7 +24796,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
@@ -23823,34 +24804,34 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
+
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
+
All characters in identifiers (with or without external linkage) are significant (6.4.2).
-J.5.4 Scopes of identifiers
+
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
+
String literals are modifiable (in which case, identical string literals should denote distinct
objects) (6.4.5).
-J.5.6 Other arithmetic types
+
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
@@ -23858,7 +24839,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
other floating types, and may be used to define float_t or double_t.
-J.5.7 Function pointer casts
+
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).
@@ -23866,69 +24847,70 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
+
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
+
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 );+ asm ( character-string-literal ); + -
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
+
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).
-J.5.13 Floating-point status flags
+
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 7.20.4.3), 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
+
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
+
Additional mappings from files to streams are supported (7.19.2).
Additional file-opening modes may be specified by characters appended to the mode
argument of the fopen function (7.19.5.3).
-J.5.16 Defined file position indicator
+
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 (7.19.7.11,
7.24.3.10).
-J.5.17 Math error reporting
+
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).
-Bibliography
+
??? x ???, 3.18 , (comma punctuator), 6.5.2, 6.7, 6.7.2.1, 6.7.2.2, 6.7.2.3, 6.7.8