ISO (the International Organization for Standardization) and IEC (the International @@ -476,6 +478,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 also for information only. +
With the introduction of new devices and extended character sets, new features may be @@ -509,12 +512,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The library clause (clause 7) is based on the 1984 /usr/group Standard. +
This International Standard specifies the form and establishes the interpretation of @@ -547,11 +552,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
1) This International Standard is designed to promote the portability of C programs among a variety of data-processing systems. It is intended for use by implementors and programmers. +
The following normative documents contain provisions which, through reference in this @@ -584,6 +590,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 designated IEC 559:1989). +
For the purposes of this International Standard, the following definitions apply. Other @@ -593,6 +600,7 @@ 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. +
access
@@ -607,12 +615,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NOTE 3 Expressions that are not evaluated do not access objects.
+
alignment
requirement that objects of a particular type be located on storage boundaries with
addresses that are particular multiples of a byte address
+
argument
@@ -622,11 +632,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
expression, or a sequence of preprocessing tokens in the comma-separated list bounded
by the parentheses in a function-like macro invocation
+
behavior
external appearance or action
+
implementation-defined behavior
@@ -636,6 +648,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
when a signed integer is shifted right.
+
locale-specific behavior
@@ -647,6 +660,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
characters other than the 26 lowercase Latin letters.
+
undefined behavior
@@ -662,6 +676,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE An example of undefined behavior is the behavior on integer overflow.
+
unspecified behavior
@@ -673,6 +688,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
evaluated.
+
bit
@@ -682,6 +698,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NOTE It need not be possible to express the address of each individual bit of an object.
+
byte
@@ -696,12 +713,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
bit.
+
character
<abstract> member of a set of elements used for the organization, control, or
representation of data
+
character
@@ -709,6 +728,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
<C> bit representation that fits in a byte
+
multibyte character
@@ -718,36 +738,42 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NOTE The extended character set is a superset of the basic character set.
+
wide character
bit representation that fits in an object of type wchar_t, capable of representing any
character in the current locale
+
constraint
restriction, either syntactic or semantic, by which the exposition of language elements is
to be interpreted
+
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
+
diagnostic message
message belonging to an implementation-defined subset of the implementation's message
output
+
forward reference
reference to a later subclause of this International Standard that contains additional
information relevant to this subclause
+
implementation
@@ -755,11 +781,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
control options, that performs translation of programs for, and supports execution of
functions in, a particular execution environment
+
implementation limit
restriction imposed upon programs by the implementation
+
object
@@ -770,6 +798,7 @@ 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.
+
parameter
@@ -779,27 +808,32 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
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
+
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
+
value
precise meaning of the contents of an object when interpreted as having a specific type
+
implementation-defined value
unspecified value where each implementation documents how the choice is made
+
indeterminate value
either an unspecified value or a trap representation
+
unspecified value
@@ -809,6 +843,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
NOTE An unspecified value cannot be a trap representation.
+
[^ x ^]
@@ -817,6 +852,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE [^2.4^] is 3, [^-2.4^] is -2.
+
[_ x _]
@@ -825,6 +861,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
EXAMPLE [_2.4_] is 2, [_-2.4_] is -3.
+
In this International Standard, ''shall'' is to be interpreted as a requirement on an @@ -878,7 +915,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
2) A strictly conforming program can use conditional features (such as those in annex F) provided the use is guarded by a #ifdef directive with the appropriate macro. For example: @@ -899,6 +936,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 implementation. +
An implementation translates C source files and executes C programs in two data- @@ -909,10 +947,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: In this clause, only a few of many possible forward references have been noted. +
A C program need not all be translated at the same time. The text of the program is kept @@ -928,6 +969,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: linkages of identifiers (6.2.2), external definitions (6.9), preprocessing directives (6.10). +
The precedence among the syntax rules of translation is specified by the following @@ -979,7 +1021,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
5) Implementations shall behave as if these separate phases occur, even though many are typically folded together in practice. Source files, translation units, and translated translation units need not necessarily be stored as files, nor need there be any one-to-one correspondence between these entities @@ -993,6 +1035,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 character. +
A conforming implementation shall produce at least one diagnostic message (identified in @@ -1010,12 +1053,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 as being both a constraint error and resulting in undefined behavior, the constraint error shall be diagnosed. -
Footnotes
8) The intent is that an implementation should identify the nature of, and where possible localize, each violation. Of course, an implementation is free to produce any number of diagnostics as long as a valid program is still correctly translated. It may also successfully translate an invalid program. +
Two execution environments are defined: freestanding and hosted. In both cases, @@ -1026,6 +1070,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 environment.
Forward references: storage durations of objects (6.2.4), initialization (6.7.8). +
In a freestanding environment (in which C program execution may take place without any @@ -1036,6 +1081,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 The effect of program termination in a freestanding environment is implementation- defined. +
A hosted environment need not be provided, but shall conform to the following @@ -1046,6 +1092,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 +
The function called at program startup is named main. The implementation declares no @@ -1083,11 +1130,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 startup and program termination. -
Footnotes
9) Thus, int can be replaced by a typedef name defined as int, or the type of argv can be written as char ** argv, and so on. +
In a hosted environment, a program may use all the functions, macros, type definitions, @@ -1097,6 +1145,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 +
If the return type of the main function is a type compatible with int, a return from the @@ -1106,11 +1155,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 termination status returned to the host environment is unspecified.
Forward references: definition of terms (7.1.1), the exit function (7.20.4.3). -
Footnotes
10) In accordance with 6.2.4, the lifetimes of objects with automatic storage duration declared in main will have ended in the former case, even where they would not have in the latter. +
The semantic descriptions in this International Standard describe the behavior of an @@ -1278,7 +1328,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 signal function (7.14), files (7.19.3). -
Footnotes
11) The IEC 60559 standard for binary floating-point arithmetic requires certain user-accessible status flags and control modes. Floating-point operations implicitly set the status flags; modes affect result values of floating-point operations. Implementations that support such floating-point state are @@ -1287,8 +1337,10 @@ 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 @@ -1345,6 +1397,7 @@ 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). +
Before any other processing takes place, each occurrence of one of the following @@ -1378,11 +1431,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
12) The trigraph sequences enable the input of characters that are not defined in the Invariant Code Set as described in ISO/IEC 646, which is a subset of the seven-bit US ASCII code set. +
The source character set may contain multibyte characters, used to represent members of @@ -1414,6 +1468,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 of a sequence of valid multibyte characters. +
The active position is that location on a display device where the next character output by @@ -1450,6 +1505,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 International Standard.
Forward references: the isprint function (7.4.1.8), the fputc function (7.19.7.3). +
Functions shall be implemented such that they may be interrupted at any time by a signal, @@ -1459,6 +1515,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 image (the instructions that compose the executable representation of a function) on a per-invocation basis. +
Both the translation and execution environments constrain the implementation of @@ -1466,6 +1523,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 environmental limits on a conforming implementation; the library-related limits are discussed in clause 7. +
The implementation shall be able to translate and execute at least one program that @@ -1506,12 +1564,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Footnotes
13) Implementations should avoid imposing fixed translation limits whenever possible.
14) See ''future language directions'' (6.11.3). +
An implementation is required to document all the limits specified in this subclause, @@ -1519,7 +1578,8 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 specified in <stdint.h>.
Forward references: integer types <stdint.h> (7.18). -
Contents +
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 @@ -1617,11 +1677,12 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 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). -
Footnotes
Contents +
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 @@ -1811,7 +1872,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 LDBL_MIN 1E-37 -
Recommended practice
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back should be the identity function. @@ -1898,7 +1959,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 (7.20), input/output <stdio.h> (7.19), mathematics <math.h> (7.12). -
Footnotes
16) The floating-point model is intended to clarify the description of each floating-point characteristic and does not require the floating-point arithmetic of the implementation to be identical. @@ -1918,8 +1979,10 @@ 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 @@ -1937,8 +2000,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
A summary of the language syntax is given in annex A. +
An identifier can denote an object; a function; a tag or a member of a structure, union, or @@ -1991,6 +2056,7 @@ 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). +
An identifier declared in different scopes or in the same scope more than once can be @@ -2030,7 +2096,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: declarations (6.7), expressions (6.5), external definitions (6.9), statements (6.8). -
Footnotes
21) There is no linkage between different identifiers.
22) A function declaration can contain the storage-class specifier static only if it is at file scope; see @@ -2039,6 +2105,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
23) As specified in 6.2.1, the later declaration might hide the prior declaration. +
If more than one declaration of a particular identifier is visible at any point in a @@ -2063,10 +2130,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
24) There is only one name space for tags even though three are possible. +
An object has a storage duration that determines its lifetime. There are three storage @@ -2107,7 +2175,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
25) The term ''constant address'' means that two pointers to the object constructed at possibly different times will compare equal. The address may be different during two different executions of the same program. @@ -2118,6 +2186,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 embedded block prior to the declaration, leaves the scope of the declaration. +
The meaning of a value stored in an object or returned by a function is determined by the @@ -2298,7 +2367,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: compatible type and composite type (6.2.7), declarations (6.7). -
Footnotes
28) Implementation-defined keywords shall have the form of an identifier reserved for any use as described in 7.1.3. @@ -2335,8 +2404,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 arguments to functions, return values from functions, and members of unions. +
The representations of all types are unspecified except as stated in this subclause. @@ -2384,7 +2455,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: declarations (6.7), expressions (6.5), lvalues, arrays, and function designators (6.3.2.1). -
Footnotes
40) A positional representation for integers that uses the binary digits 0 and 1, in which the values represented by successive bits are additive, begin with 1, and are multiplied by successive integral powers of 2, except perhaps the bit with the highest position. (Adapted from the American National @@ -2403,6 +2474,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 on values of type T may distinguish between them. +
For unsigned integer types other than unsigned char, the bits of the object @@ -2459,7 +2531,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 for signed integer types the width is one greater than the precision. -
Footnotes
44) Some combinations of padding bits might generate trap representations, for example, if one padding bit is a parity bit. Regardless, no arithmetic operation on valid values can generate a trap representation other than as part of an exceptional condition such as an overflow, and this cannot occur @@ -2473,6 +2545,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 bits. +
Two types have compatible type if their types are the same. Additional rules for @@ -2526,12 +2599,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 int f(int (*)(char *), double (*)[3]); -
Footnotes
46) Two types need not be identical to be compatible.
47) As specified in 6.2.1, the later declaration might hide the prior declaration. +
Several operators convert operand values from one type to another automatically. This @@ -2544,8 +2618,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 representation.
Forward references: cast operators (6.5.4). +
Every integer type has an integer conversion rank defined as follows: @@ -2589,17 +2665,19 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
Forward references: enumeration specifiers (6.7.2.2), structure and union specifiers (6.7.2.1). -
Footnotes
48) The integer promotions are applied only: as part of the usual arithmetic conversions, to certain argument expressions, to the operands of the unary +, -, and ~ operators, and to both operands of the shift operators, as specified by their respective subclauses. +
When any scalar value is converted to _Bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1. +
When a value with integer type is converted to another integer type other than _Bool, if @@ -2612,10 +2690,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 Otherwise, the new type is signed and the value cannot be represented in it; either the result is implementation-defined or an implementation-defined signal is raised. -
Footnotes
49) The rules describe arithmetic on the mathematical value, not the value of a given type of expression. +
When a finite value of real floating type is converted to an integer type other than _Bool, @@ -2631,12 +2710,13 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 in an implementation-defined manner. If the value being converted is outside the range of values that can be represented, the behavior is undefined. -
Footnotes
50) The remaindering operation performed when a value of integer type is converted to unsigned type need not be performed when a value of real floating type is converted to unsigned type. Thus, the range of portable real floating values is (-1, Utype_MAX+1). +
When a float is promoted to double or long double, or a double is promoted @@ -2652,11 +2732,13 @@ 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. +
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. +
When a value of real type is converted to a complex type, the real part of the complex @@ -2667,6 +2749,7 @@ 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. +
Many operators that expect operands of arithmetic type cause conversions and yield result @@ -2716,7 +2799,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
51) For example, addition of a double _Complex and a float entails just the conversion of the float operand to double (and yields a double _Complex result). @@ -2724,8 +2807,10 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 described in 6.3.1.4 and 6.3.1.5. +
An lvalue is an expression with an object type or an incomplete type other than void;53) @@ -2762,7 +2847,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
53) The name ''lvalue'' comes originally from the assignment expression E1 = E2, in which the left operand E1 is required to be a (modifiable) lvalue. It is perhaps better considered as representing an object ''locator value''. What is sometimes called ''rvalue'' is in this International Standard described @@ -2774,6 +2859,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 designator and violates the constraint in 6.5.3.4. +
The (nonexistent) value of a void expression (an expression that has type void) shall not @@ -2782,6 +2868,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 expression, its value or designator is discarded. (A void expression is evaluated for its side effects.) +
A pointer to void may be converted to or from a pointer to any incomplete or object @@ -2828,7 +2915,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 capable of holding object pointers (7.18.1.4), simple assignment (6.5.16.1). -
Footnotes
55) The macro NULL is defined in <stddef.h> (and other headers) as a null pointer constant; see 7.17.
56) The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to @@ -2839,8 +2926,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 correctly aligned for a pointer to type C. +
Syntax
token:
@@ -2858,11 +2946,11 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
punctuator
each non-white-space character that cannot be one of the above
-Constraints
Each preprocessing token that is converted to a token shall have the lexical form of a keyword, an identifier, a constant, a string literal, or a punctuator. -
Semantics
A token is the minimal lexical element of the language in translation phases 7 and 8. The categories of tokens are: keywords, identifiers, constants, string literals, and punctuators. @@ -2907,13 +2995,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 (6.5.3.1), preprocessing directives (6.10), preprocessing numbers (6.4.8), string literals (6.4.5). -
Footnotes
58) An additional category, placemarkers, is used internally in translation phase 4 (see 6.10.3.3); it cannot occur in source files. +
Syntax
keyword: one of
@@ -2928,7 +3017,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
double long typedef
else register union
-Semantics
The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for @@ -2938,14 +3027,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
59) One possible specification for imaginary types appears in annex G. +
Syntax
identifier:
@@ -2964,7 +3055,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
digit: one of
0 1 2 3 4 5 6 7 8 9
-Semantics
An identifier is a sequence of nondigit characters (including the underscore _, the lowercase and uppercase Latin letters, and other characters) and digits, which designates @@ -2984,7 +3075,7 @@ 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 @@ -2996,15 +3087,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 identifiers differ only in nonsignificant characters, the behavior is undefined.
Forward references: universal character names (6.4.3), macro replacement (6.10.3). -
Footnotes
60) On systems in which linkers cannot accept extended characters, an encoding of the universal character name may be used in forming valid external identifiers. For example, some otherwise unused character or sequence of characters may be used to encode the \u in a universal character name. Extended characters may produce a long external identifier. +
Semantics
The identifier __func__ shall be implicitly declared by the translator as if, immediately following the opening brace of each function definition, the declaration @@ -3038,13 +3130,14 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
61) Since the name __func__ is reserved for any use by the implementation (7.1.3), if any other identifier is explicitly declared using the name __func__, the behavior is undefined. +
Syntax
universal-character-name:
@@ -3054,16 +3147,16 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
hexadecimal-digit hexadecimal-digit
hexadecimal-digit hexadecimal-digit
-Constraints
A universal character name shall not specify a character whose short identifier is less than 00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through DFFF inclusive.62) -
Description
Universal character names may be used in identifiers, character constants, and string literals to designate characters that are not in the basic character set. -
Semantics
The universal character name \Unnnnnnnn designates the character whose eight-digit short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.63) Similarly, the universal @@ -3075,7 +3168,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 -
Footnotes
62) The disallowed characters are the characters in the basic character set and the code positions reserved by ISO/IEC 10646 for control characters, the character DELETE, and the S-zone (reserved for use by UTF-16). @@ -3083,8 +3176,9 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
63) Short identifiers for characters were first specified in ISO/IEC 10646-1/AMD9:1997. +
Syntax
constant:
@@ -3093,16 +3187,17 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
enumeration-constant
character-constant
-Constraints
Each constant shall have a type and the value of a constant shall be in the range of representable values for its type. -
Semantics
Each constant has a type, determined by its form and value, as detailed later. +
Syntax
@@ -3141,7 +3236,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007
long-long-suffix: one of
ll LL
-Description
An integer constant begins with a digit, but has no period or exponent part. It may have a prefix that specifies its base and a suffix that specifies its type. @@ -3151,7 +3246,7 @@ WG14/N1256 Committee Draft -- Septermber 7, 2007 digits 0 through 7 only. A hexadecimal constant consists of the prefix 0x or 0X followed by a sequence of the decimal digits and the letters a (or A) through f (or F) with values 10 through 15 respectively. -
Semantics
The value of a decimal constant is computed base 10; that of an octal constant, base 8; that of a hexadecimal constant, base 16. The lexically first digit is the most significant. @@ -3232,8 +3327,9 @@ unsigned long long int its list and has no extended integer type, then the integer constant has no type. +
Syntax
@@ -3272,7 +3368,7 @@ unsigned long long int
floating-suffix: one of
f l F L
-Description
A floating constant has a significand part that may be followed by an exponent part and a suffix that specifies its type. The components of the significand part may include a digit @@ -3281,7 +3377,7 @@ unsigned long long int e, E, p, or P followed by an exponent consisting of an optionally signed digit sequence. Either the whole-number part or the fraction part has to be present; for decimal floating constants, either the period or the exponent part has to be present. -
Semantics
The significand part is interpreted as a (decimal or hexadecimal) rational number; the digit sequence in the exponent part is interpreted as a decimal integer. For decimal @@ -3300,7 +3396,7 @@ unsigned long long int 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 @@ -3316,25 +3412,27 @@ unsigned long long int -
Footnotes
64) The specification for the library functions recommends more accurate conversion than required for floating constants (see 7.20.1.3). +
Syntax
enumeration-constant:
identifier
-Semantics
An identifier declared as an enumeration constant has type int.
Forward references: enumeration specifiers (6.7.2.2). +
Syntax
@@ -3364,7 +3462,7 @@ unsigned long long int
\x hexadecimal-digit
hexadecimal-escape-sequence hexadecimal-digit
-Description
An integer character constant is a sequence of one or more multibyte characters enclosed in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the @@ -3411,12 +3509,12 @@ unsigned long long int -
Constraints
The value of an octal or hexadecimal escape sequence shall be in the range of representable values for the type unsigned char for an integer character constant, or the unsigned type corresponding to wchar_t for a wide character constant. -
Semantics
An integer character constant has type int. The value of an integer character constant containing a single character that maps to a single-byte execution character is the @@ -3462,13 +3560,14 @@ unsigned long long int (7.20.7.2). -
Footnotes
65) The semantics of these characters were discussed in 5.2.2. If any other character follows a backslash, the result is not a token and a diagnostic is required. See ''future language directions'' (6.11.4). +
Syntax
string-literal:
@@ -3482,7 +3581,7 @@ unsigned long long int
the double-quote ", backslash \, or new-line character
escape-sequence
-Description
A character string literal is a sequence of zero or more multibyte characters enclosed in double-quotes, as in "xyz". A wide string literal is the same, except prefixed by the @@ -3493,7 +3592,7 @@ unsigned long long int character constant, except that the single-quote ' is representable either by itself or by the escape sequence \', but the double-quote " shall be represented by the escape sequence \". -
Semantics
In translation phase 6, the multibyte character sequences specified by any sequence of adjacent character and wide string literal tokens are concatenated into a single multibyte @@ -3529,13 +3628,14 @@ unsigned long long int
Forward references: common definitions <stddef.h> (7.17), the mbstowcs function (7.20.8.1). -
Footnotes
66) A character string literal need not be a string (see 7.1.1), because a null character may be embedded in it by a \0 escape sequence. +
Syntax
punctuator: one of
@@ -3547,7 +3647,7 @@ unsigned long long int
, # ##
<: :> <% %> %: %:%:
-Semantics
A punctuator is a symbol that has independent syntactic and semantic significance. Depending on context, it may specify an operation to be performed (which in turn may @@ -3568,15 +3668,16 @@ unsigned long long int
Forward references: expressions (6.5), declarations (6.7), preprocessing directives (6.10), statements (6.8). -
Footnotes
67) These tokens are sometimes called ''digraphs''.
68) Thus [ and <: behave differently when ''stringized'' (see 6.10.3.2), but can otherwise be freely interchanged. +
Syntax
header-name:
@@ -3595,7 +3696,7 @@ unsigned long long int
any member of the source character set except
the new-line character and "
-Semantics
The sequences in both forms of header names are mapped in an implementation-defined manner to headers or external source file names as specified in 6.10.2. @@ -3627,14 +3728,15 @@ unsigned long long int
Forward references: source file inclusion (6.10.2). -
Footnotes
69) Thus, sequences of characters that resemble escape sequences cause undefined behavior.
70) For an example of a header name preprocessing token used in a #pragma directive, see 6.10.9. +
Syntax
pp-number:
@@ -3648,14 +3750,14 @@ unsigned long long int
pp-number P sign
pp-number .
-Description
A preprocessing number begins with a digit optionally preceded by a period (.) and may be followed by valid identifier characters and the character sequences e+, e-, E+, E-, p+, p-, P+, or P-.
Preprocessing number tokens lexically include all floating and integer constant tokens. -
Semantics
A preprocessing number does not have type or a value; it acquires both after a successful conversion (as part of translation phase 7) to a floating constant token or an integer @@ -3664,6 +3766,7 @@ unsigned long long int +
Except within a character constant, a string literal, or a comment, the characters /* @@ -3697,10 +3800,11 @@ unsigned long long int -
Footnotes
71) Thus, /* ... */ comments do not nest. +
An expression is a sequence of operators and operands that specifies computation of a @@ -3764,7 +3868,7 @@ unsigned long long int -
Footnotes
72) A floating-point status flag is not an object and can be set more than once within an expression.
73) This paragraph renders undefined statement expressions such as @@ -3803,8 +3907,9 @@ unsigned long long int documented. +
Syntax
primary-expression:
@@ -3813,7 +3918,7 @@ unsigned long long int
string-literal
( expression )
-Semantics
An identifier is a primary expression, provided it has been declared as designating an object (in which case it is an lvalue) or a function (in which case it is a function @@ -3830,12 +3935,13 @@ unsigned long long int designator, or a void expression.
Forward references: declarations (6.7). -
Footnotes
79) Thus, an undeclared identifier is a violation of the syntax. +
Syntax
postfix-expression:
@@ -3860,12 +3966,13 @@ unsigned long long int
argument-expression-list , assignment-expression
+Constraints
One of the expressions shall have type ''pointer to object type'', the other expression shall have integer type, and the result has type ''type''. -
Semantics
A postfix expression followed by an expression in square brackets [] is a subscripted designation of an element of an array object. The definition of the subscript operator [] @@ -3898,8 +4005,9 @@ unsigned long long int (6.5.3.2), array declarators (6.7.5.2). +
Constraints
The expression that denotes the called function80) shall have type pointer to function returning void or returning an object type other than an array type. @@ -3908,7 +4016,7 @@ unsigned long long int number of arguments shall agree with the number of parameters. Each argument shall have a type such that its value may be assigned to an object with the unqualified version of the type of its corresponding parameter. -
Semantics
A postfix expression followed by parentheses () containing a possibly empty, comma- separated list of expressions is a function call. The postfix expression denotes the called @@ -3978,7 +4086,7 @@ unsigned long long int
Forward references: function declarators (including prototypes) (6.7.5.3), function definitions (6.9.1), the return statement (6.8.6.4), simple assignment (6.5.16.1). -
Footnotes
80) Most often, this is the result of converting an identifier that is a function designator.
81) A function may change the values of its parameters, but these changes cannot affect the values of the @@ -3987,8 +4095,9 @@ unsigned long long int adjusted to have a pointer type as described in 6.9.1. +
Constraints
The first operand of the . operator shall have a qualified or unqualified structure or union type, and the second operand shall name a member of that type. @@ -3997,7 +4106,7 @@ unsigned long long int structure'' or ''pointer to qualified or unqualified union'', and the second operand shall name a member of the type pointed to. -
Semantics
A postfix expression followed by the . operator and an identifier designates a member of a structure or union object. The value is that of the named member,82) and is an lvalue if @@ -4091,7 +4200,7 @@ unsigned long long int specifiers (6.7.2.1). -
Footnotes
82) If the member used to access the contents of a union object is not the same as the member last used to store a value in the object, the appropriate part of the object representation of the value is reinterpreted as an object representation in the new type as described in 6.2.6 (a process sometimes called "type @@ -4101,12 +4210,13 @@ unsigned long long int its operand), the expression (&E)->MOS is the same as E.MOS. +
Constraints
The operand of the postfix increment or decrement operator shall have qualified or unqualified real or pointer type and shall be a modifiable lvalue. -
Semantics
The result of the postfix ++ operator is the value of the operand. After the result is obtained, the value of the operand is incremented. (That is, the value 1 of the appropriate @@ -4120,8 +4230,9 @@ unsigned long long int it).
Forward references: additive operators (6.5.6), compound assignment (6.5.16.2). +
Constraints
The type name shall specify an object type or an array of unknown size, but not a variable length array type. @@ -4131,7 +4242,7 @@ unsigned long long int
If the compound literal occurs outside the body of a function, the initializer list shall consist of constant expressions. -
Semantics
A postfix expression that consists of a parenthesized type name followed by a brace- enclosed list of initializers is a compound literal. It provides an unnamed object whose @@ -4255,7 +4366,7 @@ unsigned long long int
Forward references: type names (6.7.6), initialization (6.7.8). -
Footnotes
84) Note that this differs from a cast expression. For example, a cast specifies a conversion to scalar types or void only, and the result of a cast expression is not an lvalue. @@ -4265,8 +4376,9 @@ unsigned long long int the same or overlapping representations. +
Syntax
unary-expression:
@@ -4280,12 +4392,13 @@ unsigned long long int
& * + - ~ !
+Constraints
The operand of the prefix increment or decrement operator shall have qualified or unqualified real or pointer type and shall be a modifiable lvalue. -
Semantics
The value of the operand of the prefix ++ operator is incremented. The result is the new value of the operand after incrementation. The expression ++E is equivalent to (E+=1). @@ -4296,15 +4409,16 @@ unsigned long long int operand is decremented.
Forward references: additive operators (6.5.6), compound assignment (6.5.16.2). +
Constraints
The operand of the unary & operator shall be either a function designator, the result of a [] or unary * operator, or an lvalue that designates an object that is not a bit-field and is not declared with the register storage-class specifier.
The operand of the unary * operator shall have pointer type. -
Semantics
The unary & operator yields the address of its operand. If the operand has type ''type'', the result has type ''pointer to type''. If the operand is the result of a unary * operator, @@ -4324,7 +4438,7 @@ unsigned long long int
Forward references: storage-class specifiers (6.7.1), structure and union specifiers (6.7.2.1). -
Footnotes
87) Thus, &*E is equivalent to E (even if E is a null pointer), and &(E1[E2]) to ((E1)+(E2)). It is always true that if E is a function designator or an lvalue that is a valid operand of the unary & operator, *&E is a function designator or an lvalue equal to E. If *P is an lvalue and T is the name of @@ -4334,12 +4448,13 @@ unsigned long long int end of its lifetime. +
Constraints
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator, integer type; of the ! operator, scalar type. -
Semantics
The result of the unary + operator is the value of its (promoted) operand. The integer promotions are performed on the operand, and the result has the promoted type. @@ -4362,13 +4477,14 @@ unsigned long long int +
Constraints
The sizeof operator shall not be applied to an expression that has function type or an incomplete type, to the parenthesized name of such a type, or to an expression that designates a bit-field member. -
Semantics
The sizeof operator yields the size (in bytes) of its operand, which may be an expression or the parenthesized name of a type. The size is determined from the type of @@ -4428,27 +4544,28 @@ unsigned long long int
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). -
Footnotes
88) When applied to a parameter declared to have array or function type, the sizeof operator yields the size of the adjusted (pointer) type (see 6.9.1). +
Syntax
cast-expression:
unary-expression
( type-name ) cast-expression
-Constraints
Unless the type name specifies a void type, the type name shall specify qualified or unqualified scalar type and the operand shall have scalar type.
Conversions that involve pointers, other than where permitted by the constraints of 6.5.16.1, shall be specified by means of an explicit cast. -
Semantics
Preceding an expression by a parenthesized type name converts the value of the expression to the named type. This construction is called a cast.89) A cast that specifies @@ -4465,13 +4582,14 @@ unsigned long long int -
Footnotes
89) A cast does not yield an lvalue. Thus, a cast to a qualified type has the same effect as a cast to the unqualified version of the type. +
Syntax
multiplicative-expression:
@@ -4480,11 +4598,11 @@ unsigned long long int
multiplicative-expression / cast-expression
multiplicative-expression % cast-expression
-Constraints
Each of the operands shall have arithmetic type. The operands of the % operator shall have integer type. -
Semantics
The usual arithmetic conversions are performed on the operands.
@@ -4498,12 +4616,13 @@ unsigned long long int fractional part discarded.90) If the quotient a/b is representable, the expression (a/b)*b + a%b shall equal a. -
Footnotes
90) This is often called ''truncation toward zero''. +
Syntax
additive-expression:
@@ -4511,7 +4630,7 @@ unsigned long long int
additive-expression + multiplicative-expression
additive-expression - multiplicative-expression
-Constraints
For addition, either both operands shall have arithmetic type, or one operand shall be a pointer to an object type and the other shall have integer type. (Incrementing is @@ -4529,7 +4648,7 @@ unsigned long long int
Semantics
If both operands have arithmetic type, the usual arithmetic conversions are performed on them. @@ -4593,7 +4712,7 @@ unsigned long long int
Forward references: array declarators (6.7.5.2), common definitions <stddef.h> (7.17). -
Footnotes
91) Another way to approach pointer arithmetic is first to convert the pointer(s) to character pointer(s): In this scheme the integer expression added to or subtracted from the converted pointer is first multiplied by the size of the object originally pointed to, and the resulting pointer is converted back to the @@ -4604,8 +4723,9 @@ unsigned long long int element'' requirements. +
Syntax
shift-expression:
@@ -4613,10 +4733,10 @@ unsigned long long int
shift-expression << additive-expression
shift-expression >> additive-expression
-Constraints
Each of the operands shall have integer type. -
Semantics
The integer promotions are performed on each of the operands. The type of the result is that of the promoted left operand. If the value of the right operand is negative or is @@ -4638,8 +4758,9 @@ unsigned long long int part of the quotient of E1 / 2E2 . If E1 has a signed type and a negative value, the resulting value is implementation-defined. +
Syntax
relational-expression:
@@ -4649,7 +4770,7 @@ unsigned long long int
relational-expression <= shift-expression
relational-expression >= shift-expression
-Constraints
One of the following shall hold:
Semantics
If both of the operands have arithmetic type, the usual arithmetic conversions are performed. @@ -4685,13 +4806,14 @@ unsigned long long int (greater than or equal to) shall yield 1 if the specified relation is true and 0 if it is false.92) The result has type int. -
Footnotes
92) The expression a<b<c is not interpreted as in ordinary mathematics. As the syntax indicates, it means (a<b)<c; in other words, ''if a is less than b, compare 1 to c; otherwise, compare 0 to c''. +
Syntax
equality-expression:
@@ -4699,7 +4821,7 @@ unsigned long long int
equality-expression == relational-expression
equality-expression != relational-expression
-Constraints
One of the following shall hold:
Semantics
The == (equal to) and != (not equal to) operators are analogous to the relational operators except for their lower precedence.93) Each of the operators yields 1 if the @@ -4741,7 +4863,7 @@ unsigned long long int array behaves the same as a pointer to the first element of an array of length one with the type of the object as its element type. -
Footnotes
93) Because of the precedences, a<b == c<d is 1 whenever a<b and c<d have the same truth-value.
94) Two objects may be adjacent in memory because they are adjacent elements of a larger array or @@ -4751,18 +4873,19 @@ unsigned long long int behavior. +
Syntax
AND-expression:
equality-expression
AND-expression & equality-expression
-Constraints
Each of the operands shall have integer type. -
Semantics
The usual arithmetic conversions are performed on the operands.
@@ -4775,18 +4898,19 @@ unsigned long long int +
Syntax
exclusive-OR-expression:
AND-expression
exclusive-OR-expression ^ AND-expression
-Constraints
Each of the operands shall have integer type. -
Semantics
The usual arithmetic conversions are performed on the operands.
@@ -4794,18 +4918,19 @@ unsigned long long int in the result is set if and only if exactly one of the corresponding bits in the converted operands is set). +
Syntax
inclusive-OR-expression:
exclusive-OR-expression
inclusive-OR-expression | exclusive-OR-expression
-Constraints
Each of the operands shall have integer type. -
Semantics
The usual arithmetic conversions are performed on the operands.
@@ -4814,18 +4939,19 @@ unsigned long long int operands is set). +
Syntax
logical-AND-expression:
inclusive-OR-expression
logical-AND-expression && inclusive-OR-expression
-Constraints
Each of the operands shall have scalar type. -
Semantics
The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it yields 0. The result has type int. @@ -4834,18 +4960,19 @@ unsigned long long int 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. +
Syntax
logical-OR-expression:
logical-AND-expression
logical-OR-expression || logical-AND-expression
-Constraints
Each of the operands shall have scalar type. -
Semantics
The || operator shall yield 1 if either of its operands compare unequal to 0; otherwise, it yields 0. The result has type int. @@ -4855,15 +4982,16 @@ unsigned long long int unequal to 0, the second operand is not evaluated. +
Syntax
conditional-expression:
logical-OR-expression
logical-OR-expression ? expression : conditional-expression
-Constraints
The first operand shall have scalar type.
@@ -4877,7 +5005,7 @@ unsigned long long int
Semantics
The first operand is evaluated; there is a sequence point after its evaluation. The second operand is evaluated only if the first compares unequal to 0; the third operand is evaluated @@ -4927,12 +5055,13 @@ unsigned long long int -
Footnotes
95) A conditional expression does not yield an lvalue. +
Syntax
assignment-expression:
@@ -4941,10 +5070,10 @@ unsigned long long int
assignment-operator: one of
= *= /= %= += -= <<= >>= &= ^= |=
-Constraints
An assignment operator shall have a modifiable lvalue as its left operand. -
Semantics
An assignment operator stores a value in the object designated by the left operand. An assignment expression has the value of the left operand after the assignment, but is not an @@ -4958,8 +5087,9 @@ unsigned long long int behavior is undefined. +
Constraints
One of the following shall hold:96)
Semantics
In simple assignment (=), the value of the right operand is converted to the type of the assignment expression and replaces the value stored in the object designated by the left @@ -5031,15 +5161,16 @@ unsigned long long int value of the const object c. -
Footnotes
96) The asymmetric appearance of these constraints with respect to type qualifiers is due to the conversion (specified in 6.3.2.1) that changes lvalues to ''the value of the expression'' and thus removes any type qualifiers that were applied to the type category of the expression (for example, it removes const but not volatile from the type int volatile * const). +
Constraints
For the operators += and -= only, either the left operand shall be a pointer to an object type and the right shall have integer type, or the left operand shall have qualified or @@ -5047,21 +5178,22 @@ unsigned long long int
For the other operators, each operand shall have arithmetic type consistent with those allowed by the corresponding binary operator. -
Semantics
A compound assignment of the form E1 op = E2 differs from the simple assignment expression E1 = E1 op (E2) only in that the lvalue E1 is evaluated only once. +
Syntax
expression:
assignment-expression
expression , assignment-expression
-Semantics
The left operand of a comma operator is evaluated as a void expression; there is a sequence point after its evaluation. Then the right operand is evaluated; the result has its @@ -5084,22 +5216,23 @@ unsigned long long int -
Footnotes
97) A comma operator does not yield an lvalue. +
Syntax
constant-expression:
conditional-expression
-Description
A constant expression can be evaluated during translation rather than runtime, and accordingly may be used in any place that a constant may be. -
Constraints
Constant expressions shall not contain assignment, increment, decrement, function-call, or comma operators, except when they are contained within a subexpression that is not @@ -5107,7 +5240,7 @@ unsigned long long int
Each constant expression shall evaluate to a constant that is in the range of representable values for its type. -
Semantics
An expression that evaluates to a constant is required in several contexts. If a floating expression is evaluated in the translation environment, the arithmetic precision and range @@ -5160,7 +5293,7 @@ unsigned long long int -
Footnotes
98) The operand of a sizeof operator is usually not evaluated (6.5.3.4).
99) An integer constant expression is used to specify the size of a bit-field member of a structure, the @@ -5176,8 +5309,9 @@ unsigned long long int the expression is a valid integer constant expression with value one. +
Syntax
declaration:
@@ -5194,7 +5328,7 @@ unsigned long long int
declarator
declarator = initializer
-Constraints
A declaration shall declare at least a declarator (other than the parameters of a function or the members of a structure or union), a tag, or the members of an enumeration. @@ -5205,7 +5339,7 @@ unsigned long long int
All declarations in the same scope that refer to the same object or function shall specify compatible types. -
Semantics
A declaration specifies the interpretation and attributes of a set of identifiers. A definition of an identifier is a declaration for that identifier that: @@ -5231,12 +5365,13 @@ unsigned long long int
Forward references: declarators (6.7.5), enumeration specifiers (6.7.2.2), initialization (6.7.8). -
Footnotes
101) Function definitions have a different syntax, described in 6.9.1. +
Syntax
storage-class-specifier:
@@ -5246,11 +5381,11 @@ unsigned long long int
auto
register
-Constraints
At most, one storage-class specifier may be given in the declaration specifiers in a declaration.102) -
Semantics
The typedef specifier is called a ''storage-class specifier'' for syntactic convenience only; it is discussed in 6.7.7. The meanings of the various linkages and storage durations @@ -5273,7 +5408,7 @@ unsigned long long int or union member objects.
Forward references: type definitions (6.7.7). -
Footnotes
102) See ''future language directions'' (6.11.5).
103) The implementation may treat any register declaration simply as an auto declaration. However, @@ -5284,8 +5419,9 @@ unsigned long long int register is sizeof. +
Syntax
type-specifier:
@@ -5304,7 +5440,7 @@ unsigned long long int
enum-specifier
typedef-name
-Constraints
At least one type specifier shall be given in the declaration specifiers in each declaration, and in the specifier-qualifier list in each struct declaration and type name. Each list of @@ -5340,7 +5476,7 @@ unsigned long long int
The type specifier _Complex shall not be used if the implementation does not provide complex types.104) -
Semantics
Specifiers for structures, unions, and enumerations are discussed in 6.7.2.1 through 6.7.2.3. Declarations of typedef names are discussed in 6.7.7. The characteristics of the @@ -5357,12 +5493,13 @@ unsigned long long int -
Footnotes
104) Freestanding implementations are not required to provide complex types. * +
Syntax
struct-or-union-specifier:
@@ -5386,7 +5523,7 @@ unsigned long long int
declarator
declaratoropt : constant-expression
-Constraints
A structure or union shall not contain a member with incomplete or function type (hence, a structure shall not contain an instance of itself, but may contain a pointer to an instance @@ -5403,7 +5540,7 @@ unsigned long long int A bit-field shall have a type that is a qualified or unqualified version of _Bool, signed int, unsigned int, or some other implementation-defined type. -
Semantics
As discussed in 6.2.5, a structure is a type consisting of a sequence of members, whose storage is allocated in an ordered sequence, and a union is a type consisting of a sequence @@ -5558,7 +5695,7 @@ unsigned long long int
Forward references: tags (6.7.2.3). -
Footnotes
105) A structure or union can not contain a member with a variably modified type because member names are not ordinary identifiers as defined in 6.2.3. @@ -5572,8 +5709,9 @@ unsigned long long int layouts. +
Syntax
enum-specifier:
@@ -5587,11 +5725,11 @@ unsigned long long int
enumeration-constant
enumeration-constant = constant-expression
-Constraints
The expression that defines the value of an enumeration constant shall be an integer constant expression that has a value representable as an int. -
Semantics
The identifiers in an enumerator list are declared as constants that have type int and may appear wherever such are permitted.109) An enumerator with = defines its @@ -5627,7 +5765,7 @@ unsigned long long int
Forward references: tags (6.7.2.3). -
Footnotes
109) Thus, the identifiers of enumeration constants declared in the same scope shall all be distinct from each other and from other identifiers declared in ordinary declarators. @@ -5635,8 +5773,9 @@ unsigned long long int been seen. +
Constraints
A specific type shall have its content defined at most once.
@@ -5648,7 +5787,7 @@ unsigned long long int enum identifier without an enumerator list shall only appear after the type it specifies is complete. -
Semantics
All declarations of structure, union, or enumerated types that have the same scope and use the same tag declare the same type. The type is incomplete111) until the closing brace @@ -5753,7 +5892,7 @@ unsigned long long int
Forward references: declarators (6.7.5), array declarators (6.7.5.2), type definitions (6.7.7). -
Footnotes
111) An incomplete type may only by used when the size of an object of that type is not needed. It is not needed, for example, when a typedef name is declared to be a specifier for a structure or union, or when a pointer to or a function returning a structure or union is being declared. (See incomplete types @@ -5767,8 +5906,9 @@ unsigned long long int
113) A similar construction with enum does not exist. +
Syntax
type-qualifier:
@@ -5776,11 +5916,11 @@ unsigned long long int
restrict
volatile
-Constraints
Types other than pointer types derived from object or incomplete types shall not be restrict-qualified. -
Semantics
The properties associated with qualified types are meaningful only for expressions that are lvalues.114) @@ -5852,7 +5992,7 @@ unsigned long long int -
Footnotes
114) The implementation may place a const object that is not volatile in a read-only region of storage. Moreover, the implementation need not allocate storage for such an object if its address is never used. @@ -5872,6 +6012,7 @@ unsigned long long int
118) Both of these can occur through the use of typedefs. +
Let D be a declaration of an ordinary identifier that provides a means of designating an @@ -5988,21 +6129,22 @@ unsigned long long int -
Footnotes
119) In other words, E depends on the value of P itself rather than on the value of an object referenced indirectly through P. For example, if identifier p has type (int **restrict), then the pointer expressions p and p+1 are based on the restricted pointer object designated by p, but the pointer expressions *p and p[1] are not. +
Syntax
function-specifier:
inline
-Constraints
Function specifiers shall be used only in the declaration of an identifier for a function.
@@ -6012,7 +6154,7 @@ unsigned long long int
In a hosted environment, the inline function specifier shall not appear in a declaration of main. -
Semantics
A function declared with an inline function specifier is an inline function. The function specifier may appear more than once; the behavior is the same as if it appeared @@ -6062,7 +6204,7 @@ unsigned long long int -
Footnotes
120) By using, for example, an alternative to the usual function call mechanism, such as ''inline substitution''. Inline substitution is not textual substitution, nor does it create a new function. Therefore, for example, the expansion of a macro used within the body of the function uses the @@ -6079,8 +6221,9 @@ unsigned long long int duration are also distinct in each of the definitions. +
Syntax
declarator:
@@ -6113,7 +6256,7 @@ unsigned long long int
identifier
identifier-list , identifier
-Semantics
Each declarator declares one identifier, and asserts that when an operand of the same form as the declarator appears in an expression, it designates a function or object with the @@ -6147,15 +6290,16 @@ unsigned long long int 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). +
Semantics
If, in the declaration ''T D1'', D1 has the form
@@ -6189,8 +6333,9 @@ unsigned long long int declares constant_ptr as an object that has type ''const-qualified pointer to int''. +-6.7.5.2 Array declarators
-Constraints
+Constraints
In addition to optional type qualifiers and the keyword static, the [ and ] may delimit an expression or *. If they delimit an expression (which specifies the size of an array), the @@ -6203,7 +6348,7 @@ unsigned long long int An ordinary identifier (as defined in 6.2.3) that has a variably modified type shall have either block scope and no linkage or function prototype scope. If an identifier is declared to be an object with static storage duration, it shall not have a variable length array type. -
Semantics
+Semantics
If, in the declaration ''T D1'', D1 has one of the forms:
@@ -6306,14 +6451,15 @@ unsigned long long int+Forward references: function declarators (6.7.5.3), function definitions (6.9.1), initialization (6.7.8). -
footnotes
+Footnotes
123) When several ''array of'' specifications are adjacent, a multidimensional array is declared.
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)
-Constraints
+Constraints
A function declarator shall not specify a return type that is a function type or an array type. @@ -6325,7 +6471,7 @@ unsigned long long int
After adjustment, the parameters in a parameter type list in a function declarator that is part of a definition of that function shall not have incomplete type. -
Semantics
+Semantics
If, in the declaration ''T D1'', D1 has the form
@@ -6473,7 +6619,7 @@ unsigned long long int+Forward references: function definitions (6.9.1), type names (6.7.6). -
footnotes
+Footnotes
125) The macros defined in the <stdarg.h> header (7.15) may be used to access arguments that correspond to the ellipsis. @@ -6482,8 +6628,9 @@ unsigned long long int
127) If both function types are ''old style'', parameter types are not compared. +
6.7.6 Type names
-Syntax
+Syntax
type-name: @@ -6502,7 +6649,7 @@ unsigned long long int direct-abstract-declaratoropt [ * ] direct-abstract-declaratoropt ( parameter-type-listopt )-Semantics
+Semantics
In several contexts, it is necessary to specify a type. This is accomplished using a type name, which is syntactically a declaration for a function or an object of that type that @@ -6531,22 +6678,23 @@ unsigned long long int -
footnotes
+Footnotes
128) As indicated by the syntax, empty parentheses in a type name are interpreted as ''function with no parameter specification'', rather than redundant parentheses around the omitted identifier. +
6.7.7 Type definitions
-Syntax
+Syntax
typedef-name: identifier-Constraints
+Constraints
If a typedef name specifies a variably modified type then it shall have block scope. -
Semantics
+Semantics
In a declaration whose storage-class specifier is typedef, each declarator defines an identifier to be a typedef name that denotes the type specified for the identifier in the way @@ -6643,8 +6791,9 @@ unsigned long long int }
6.7.8 Initialization
-Syntax
+Syntax
initializer: @@ -6663,7 +6812,7 @@ unsigned long long int [ constant-expression ] . identifier-Constraints
+Constraints
No initializer shall attempt to provide a value for an object not contained within the entity being initialized. @@ -6692,7 +6841,7 @@ unsigned long long int 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. -
Semantics
+Semantics
An initializer specifies the initial value stored in an object.
@@ -6963,7 +7112,7 @@ unsigned long long int
Forward references: common definitions <stddef.h> (7.17). -
footnotes
+Footnotes
129) If the initializer list for a subaggregate or contained union does not begin with a left brace, its subobjects are initialized as usual, but the subaggregate or contained union does not become the current object: current objects are associated only with brace-enclosed initializer lists. @@ -6980,8 +7129,9 @@ unsigned long long int
133) In particular, the evaluation order need not be the same as the order of subobject initialization. +
6.8 Statements and blocks
-Syntax
+Syntax
statement: @@ -6992,7 +7142,7 @@ unsigned long long int iteration-statement jump-statement-Semantics
+Semantics
A statement specifies an action to be performed. Except as indicated, statements are executed in sequence. @@ -7013,8 +7163,9 @@ unsigned long long int
Forward references: expression and null statements (6.8.3), selection statements (6.8.4), iteration statements (6.8.5), the return statement (6.8.6.4). +
6.8.1 Labeled statements
-Syntax
+Syntax
labeled-statement: @@ -7022,22 +7173,23 @@ unsigned long long int case constant-expression : statement default : statement-Constraints
+Constraints
A case or default label shall appear only in a switch statement. Further constraints on such labels are discussed under the switch statement.
Label names shall be unique within a function. -
Semantics
+Semantics
Any statement may be preceded by a prefix that declares an identifier as a label name. Labels in themselves do not alter the flow of control, which continues unimpeded across them.
Forward references: the goto statement (6.8.6.1), the switch statement (6.8.4.2). +
6.8.2 Compound statement
-Syntax
+Syntax
compound-statement: @@ -7049,18 +7201,19 @@ unsigned long long int declaration statement-Semantics
+Semantics
A compound statement is a block. +
6.8.3 Expression and null statements
-Syntax
+Syntax
expression-statement: expressionopt ;-Semantics
+Semantics
The expression in an expression statement is evaluated as a void expression for its side effects.134) @@ -7108,12 +7261,13 @@ unsigned long long int
Forward references: iteration statements (6.8.5). -
footnotes
+Footnotes
134) Such as assignments, and function calls which have side effects. +
6.8.4 Selection statements
-Syntax
+Syntax
selection-statement: @@ -7121,7 +7275,7 @@ unsigned long long int if ( expression ) statement else statement switch ( expression ) statement-Semantics
+Semantics
A selection statement selects among a set of statements depending on the value of a controlling expression. @@ -7130,11 +7284,12 @@ unsigned long long int enclosing block. Each associated substatement is also a block whose scope is a strict subset of the scope of the selection statement. +
6.8.4.1 The if statement
-Constraints
+Constraints
The controlling expression of an if statement shall have scalar type. -
Semantics
+Semantics
In both forms, the first substatement is executed if the expression compares unequal to 0. In the else form, the second substatement is executed if the expression compares equal @@ -7145,8 +7300,9 @@ unsigned long long int An else is associated with the lexically nearest preceding if that is allowed by the syntax. +
6.8.4.2 The switch statement
-Constraints
+Constraints
The controlling expression of a switch statement shall have integer type.
@@ -7160,7 +7316,7 @@ unsigned long long int (Any enclosed switch statement may have a default label or case constant expressions with values that duplicate case constant expressions in the enclosing switch statement.) -
Semantics
+Semantics
A switch statement causes control to jump to, into, or past the statement that is the switch body, depending on the value of a controlling expression, and on the presence of a @@ -7174,7 +7330,7 @@ unsigned long long int 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
+Implementation limits
As discussed in 5.2.4.1, the implementation may limit the number of case values in a switch statement. @@ -7202,13 +7358,14 @@ unsigned long long int access an indeterminate value. Similarly, the call to the function f cannot be reached. -
footnotes
+Footnotes
135) That is, the declaration either precedes the switch statement, or it follows the last case or default label associated with the switch that is in the block containing the declaration. +
6.8.5 Iteration statements
-Syntax
+Syntax
iteration-statement: @@ -7217,13 +7374,13 @@ unsigned long long int for ( expressionopt ; expressionopt ; expressionopt ) statement for ( declaration expressionopt ; expressionopt ) statement-Constraints
+Constraints
The controlling expression of an iteration statement shall have scalar type.
The declaration part of a for statement shall only declare identifiers for objects having storage class auto or register. -
Semantics
+Semantics
An iteration statement causes a statement called the loop body to be executed repeatedly until the controlling expression compares equal to 0. The repetition occurs regardless of @@ -7238,21 +7395,24 @@ unsigned long long int -
footnotes
+Footnotes
136) Code jumped over is not executed. In particular, the controlling expression of a for or while statement is not evaluated before entering the loop body, nor is clause-1 of a for statement. +
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 @@ -7270,15 +7430,16 @@ unsigned long long int Both clause-1 and expression-3 can be omitted. An omitted expression-2 is replaced by a nonzero constant. -
footnotes
+Footnotes
137) Thus, clause-1 specifies initialization for the loop, possibly declaring one or more variables for use in the loop; the controlling expression, expression-2, specifies an evaluation made before each iteration, such that execution of the loop continues until the expression compares equal to 0; and expression-3 specifies an operation (such as incrementing) that is performed after each iteration. +
6.8.6 Jump statements
-Syntax
+Syntax
jump-statement: @@ -7287,7 +7448,7 @@ unsigned long long int break ; return expressionopt ;-Semantics
+Semantics
A jump statement causes an unconditional jump to another place. @@ -7296,13 +7457,14 @@ unsigned long long int +
6.8.6.1 The goto statement
-Constraints
+Constraints
The identifier in a goto statement shall name a label located somewhere in the enclosing function. A goto statement shall not jump from outside the scope of an identifier having a variably modified type to inside the scope of that identifier. -
Semantics
+Semantics
A goto statement causes an unconditional jump to the statement prefixed by the named label in the enclosing function. @@ -7353,11 +7515,12 @@ unsigned long long int
6.8.6.2 The continue statement
-Constraints
+Constraints
A continue statement shall appear only in or as a loop body. -
Semantics
+Semantics
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 @@ -7373,15 +7536,16 @@ unsigned long long int 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) -
footnotes
+Footnotes
138) Following the contin: label is a null statement. +
6.8.6.3 The break statement
-Constraints
+Constraints
A break statement shall appear only in or as a switch body or loop body. -
Semantics
+Semantics
A break statement terminates execution of the smallest enclosing switch or iteration statement. @@ -7390,13 +7554,14 @@ unsigned long long int +
6.8.6.4 The return statement
-Constraints
+Constraints
A return statement with an expression shall not appear in a function whose return type is void. A return statement without an expression shall only appear in a function whose return type is void. -
Semantics
+Semantics
A return statement terminates execution of the current function and returns control to its caller. A function may have any number of return statements. @@ -7434,15 +7599,16 @@ unsigned long long int -
footnotes
+Footnotes
139) The return statement is not an assignment. The overlap restriction of subclause 6.5.16.1 does not apply to the case of function return. The representation of floating-point values may have wider range or precision and is determined by FLT_EVAL_METHOD. A cast may be used to remove this extra range and precision. +
6.9 External definitions
-Syntax
+Syntax
translation-unit: @@ -7452,7 +7618,7 @@ unsigned long long int function-definition declaration-Constraints
+Constraints
The storage-class specifiers auto and register shall not appear in the declaration specifiers in an external declaration. @@ -7462,7 +7628,7 @@ unsigned long long int linkage is used in an expression (other than as a part of the operand of a sizeof operator whose result is an integer constant), there shall be exactly one external definition for the identifier in the translation unit. -
Semantics
+Semantics
As discussed in 5.1.1.1, the unit of program text after preprocessing is a translation unit, which consists of a sequence of external declarations. These are described as ''external'' @@ -7482,13 +7648,14 @@ unsigned long long int -
footnotes
+Footnotes
140) Thus, if an identifier declared with external linkage is not used in an expression, there need be no external definition for it. +
6.9.1 Function definitions
-Syntax
+Syntax
function-definition: @@ -7497,7 +7664,7 @@ unsigned long long int declaration declaration-list declaration-Constraints
+Constraints
The identifier declared in a function definition (which is the name of the function) shall have a function type, as specified by the declarator portion of the function definition.141) @@ -7523,7 +7690,7 @@ unsigned long long int -
Semantics
+Semantics
The declarator in a function definition specifies the name of the function being defined and the identifiers of its parameters. If the declarator includes a parameter type list, the @@ -7607,7 +7774,7 @@ unsigned long long int
Footnotes
141) The intent is that the type category in a function definition cannot be inherited from a typedef:
142) See ''future language directions'' (6.11.7).
+ Semantics
If the declaration of an identifier for an object has file scope and an initializer, the
declaration is an external definition for the identifier.
@@ -7673,8 +7841,9 @@ unsigned long long int
zero on program startup.
+ Syntax
Description
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the
following constraints: The first token in the sequence is a # preprocessing token that (at
@@ -7749,14 +7918,14 @@ unsigned long long int
When in a group that is skipped (6.10.1), the directive syntax is relaxed to allow any
sequence of preprocessing tokens to occur between the directive name and the following
new-line character.
- Constraints
The only white-space characters that shall appear between preprocessing tokens within a
preprocessing directive (from just after the introducing # preprocessing token through
just before the terminating new-line character) are space and horizontal-tab (including
spaces that have replaced comments or possibly other white-space characters in
translation phase 3).
- Semantics
The implementation can process and skip sections of source files conditionally, include
other source files, and replace macros. These capabilities are called preprocessing,
@@ -7775,14 +7944,15 @@ unsigned long long int
replaced.
- Footnotes
143) Thus, preprocessing directives are commonly called ''lines''. These ''lines'' have no other syntactic
significance, as all white space is equivalent except in certain situations during preprocessing (see the
# character string literal creation operator in 6.10.3.2, for example).
+ Constraints
The expression that controls conditional inclusion shall be an integer constant expression
except that: it shall not contain a cast; identifiers (including those lexically identical to
@@ -7807,7 +7977,7 @@ unsigned long long int
Each preprocessing token that remains (in the list of preprocessing tokens that will
become the controlling expression) after all macro replacements have occurred shall be in
the lexical form of a token (6.4).
- Semantics
Preprocessing directives of the forms
Forward references: macro replacement (6.10.3), source file inclusion (6.10.2), largest
integer types (7.18.1.5).
- Footnotes
144) Because the controlling constant expression is evaluated during translation phase 4, all identifiers
either are or are not macro names -- there simply are no keywords, enumeration constants, etc.
@@ -7880,12 +8050,13 @@ unsigned long long int
including within a preprocessing directive.
@@ -7627,8 +7794,9 @@ unsigned long long int
+6.9.2 External object definitions
-Semantics
+6.10 Preprocessing directives
-Syntax
+
@@ -7730,7 +7899,7 @@ unsigned long long int
new-line:
the new-line character
-Description
+Constraints
+Semantics
+footnotes
+6.10.1 Conditional inclusion
-Constraints
+Semantics
+
@@ -7859,7 +8029,7 @@ unsigned long long int
footnotes
+
Constraints
A #include directive shall identify a header or source file that can be processed by the implementation. -
Semantics
A preprocessing directive of the form
@@ -7962,13 +8133,14 @@ unsigned long long int+Forward references: macro replacement (6.10.3). -
footnotes
+Footnotes
148) Note that adjacent string literals are not concatenated into a single string literal (see the translation phases in 5.1.1.2); thus, an expansion that results in two string literals is an invalid directive. +
6.10.3 Macro replacement
-Constraints
+Constraints
Two replacement lists are identical if and only if the preprocessing tokens in both have the same number, ordering, spelling, and white-space separation, where all white-space @@ -7997,7 +8169,7 @@ unsigned long long int
A parameter identifier in a function-like macro shall be uniquely declared within its scope. -
Semantics
+Semantics
The identifier immediately following the define is called the macro name. There is one name space for macro names. Any white-space characters preceding or following the @@ -8051,7 +8223,7 @@ unsigned long long int merger, the number of arguments is one more than the number of parameters in the macro definition (excluding the ...). -
footnotes
+Footnotes
149) Since, by macro-replacement time, all character constants and string literals are preprocessing tokens, not sequences possibly containing identifier-like subsequences (see 5.1.1.2, translation phases), they are never scanned for macro names or parameters. @@ -8059,6 +8231,7 @@ unsigned long long int
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, @@ -8073,12 +8246,13 @@ unsigned long long int were a parameter, and the variable arguments shall form the preprocessing tokens used to replace it. +
6.10.3.2 The # operator
-Constraints
+Constraints
Each # preprocessing token in the replacement list for a function-like macro shall be followed by a parameter as the next preprocessing token in the replacement list. -
Semantics
+Semantics
If, in the replacement list, a parameter is immediately preceded by a # preprocessing token, both are replaced by a single character string literal preprocessing token that @@ -8097,12 +8271,13 @@ unsigned long long int ## operators is unspecified. +
6.10.3.3 The ## operator
-Constraints
+Constraints
A ## preprocessing token shall not occur at the beginning or at the end of a replacement list for either form of macro definition. -
Semantics
+Semantics
If, in the replacement list of a function-like macro, a parameter is immediately preceded or followed by a ## preprocessing token, the parameter is replaced by the corresponding @@ -8144,11 +8319,12 @@ unsigned long long int -
footnotes
+Footnotes
151) Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that exist only within translation phase 4. +
6.10.3.4 Rescanning and further replacement
After all parameters in the replacement list have been substituted and # and ## @@ -8167,6 +8343,7 @@ unsigned long long int 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 @@ -8325,11 +8502,12 @@ unsigned long long int
Constraints
The string literal of a #line directive, if present, shall be a character string literal. -
Semantics
The line number of the current source line is one greater than the number of new-line characters read or introduced in translation phase 1 (5.1.1.2) while processing the source @@ -8362,8 +8540,9 @@ unsigned long long int previous forms and is then processed as appropriate. +
Semantics
A preprocessing directive of the form
@@ -8372,8 +8551,9 @@ unsigned long long int causes the implementation to produce a diagnostic message that includes the specified sequence of preprocessing tokens. +-6.10.6 Pragma directive
-Semantics
+Semantics
A preprocessing directive of the form
@@ -8404,7 +8584,7 @@ unsigned long long int --footnotes
+Footnotes
152) An implementation is not required to perform macro replacement in pragmas, but it is permitted except for in standard pragmas (where STDC immediately follows pragma). If the result of macro replacement in a non-standard pragma has the same form as a standard pragma, the behavior is still @@ -8414,8 +8594,9 @@ unsigned long long int
153) See ''future language directions'' (6.11.8). +
6.10.7 Null directive
-Semantics
+Semantics
A preprocessing directive of the form
@@ -8423,6 +8604,7 @@ unsigned long long inthas no effect. +6.10.8 Predefined macro names
The following macro names154) shall be defined by the implementation: @@ -8481,7 +8663,7 @@ unsigned long long int in any standard header.
Forward references: the asctime function (7.23.3.1), standard headers (7.1.2). -
footnotes
+Footnotes
154) See ''future language directions'' (6.11.9).
155) The presumed source file name and line number can be changed by the #line directive. @@ -8491,8 +8673,9 @@ unsigned long long int int that is increased with each revision of this International Standard. +
6.10.9 Pragma operator
-Semantics
+Semantics
A unary operator expression of the form:
@@ -8524,58 +8707,71 @@ unsigned long long int LISTING ( ..\listing.dir )+6.11 Future language directions
+6.11.1 Floating types
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
+7.1 Introduction
+7.1.1 Definitions of terms
A string is a contiguous sequence of characters terminated by and including the first null @@ -8609,7 +8805,7 @@ unsigned long long int -
footnotes
+Footnotes
157) The functions that make use of the decimal-point character are the numeric conversion functions (7.20.1, 7.24.4.1) and the formatted input/output functions (7.19.6, 7.24.2). @@ -8619,6 +8815,7 @@ unsigned long long int implementation's choice. +
7.1.2 Standard headers
Each library function is declared, with a type that includes a prototype, in a header,159) @@ -8666,11 +8863,12 @@ unsigned long long int -
footnotes
+Footnotes
159) A header is not necessarily a source file, nor are the < and > delimited sequences in header names necessarily valid source file names. +
7.1.3 Reserved identifiers
Each header declares or defines all identifiers listed in its associated subclause, and @@ -8700,11 +8898,12 @@ unsigned long long int If the program removes (with #undef) any macro definition of an identifier in the first group listed above, the behavior is undefined. -
footnotes
+Footnotes
160) The list of reserved identifiers with external linkage includes errno, math_errhandling, setjmp, and va_end. +
7.1.4 Use of library functions
Each of the following statements applies unless explicitly stated otherwise in the detailed @@ -8782,7 +8981,7 @@ unsigned long long int
footnotes
+Footnotes
161) This means that an implementation shall provide an actual function for each library function, even if it also provides a macro for that function. @@ -8810,7 +9009,8 @@ unsigned long long int
164) Thus, a signal handler cannot, in general, call standard library functions. -
7.2 Diagnostics
+Contents +
7.2 Diagnostics <assert.h>
The header <assert.h> defines the assert macro and refers to another macro,
@@ -8829,16 +9029,18 @@ unsigned long long int macro definition is suppressed in order to access an actual function, the behavior is undefined. ++7.2.1 Program diagnostics
+7.2.1.1 The assert macro
-Synopsis
+Synopsis
#include <assert.h> void assert(scalar expression);-Description
+Description
The assert macro puts diagnostic tests into programs; it expands to a void expression. When it is executed, if expression (which shall have a scalar type) is false (that is, @@ -8848,7 +9050,7 @@ unsigned long long int the preprocessing macros __FILE__ and __LINE__ and of the identifier __func__) on the standard error stream in an implementation-defined format.165) It then calls the abort function. -
Returns
+Returns
The assert macro returns no value.
Forward references: the abort function (7.20.4.1). @@ -8858,13 +9060,15 @@ unsigned long long int -
footnotes
+Footnotes
165) The message written might be of the form: Assertion failed: expression, function abc, file xyz, line nnn. -
7.3 Complex arithmetic
+Contents +
7.3 Complex arithmetic <complex.h>
+7.3.1 Introduction
The header <complex.h> defines macros and declares functions that support complex @@ -8912,7 +9116,7 @@ unsigned long long int -
footnotes
+Footnotes
166) See ''future library directions'' (7.26.1).
167) The imaginary unit is a number i such that i2 = -1. @@ -8920,11 +9124,13 @@ unsigned long long int
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 @@ -8944,14 +9150,15 @@ unsigned long long int the finite endpoint of the cut along the negative real axis approaches the cut from above, so the cut maps to the positive imaginary axis. +
7.3.4 The CX_LIMITED_RANGE pragma
-Synopsis
+Synopsis
#include <complex.h> #pragma STDC CX_LIMITED_RANGE on-off-switch-Description
+Description
The usual mathematical formulas for complex multiply, divide, and absolute value are problematic because of their treatment of infinities and because of undue overflow and @@ -8970,7 +9177,7 @@ unsigned long long int compound statement. If this pragma is used in any other context, the behavior is undefined. The default state for the pragma is ''off''. -
footnotes
+Footnotes
169) The purpose of the pragma is to allow the implementation to use the formulas:
@@ -8981,10 +9188,12 @@ unsigned long long int where the programmer can determine they are safe.+7.3.5 Trigonometric functions
+7.3.5.1 The cacos functions
-Synopsis
+Synopsis
#include <complex.h> @@ -8992,18 +9201,19 @@ unsigned long long int float complex cacosf(float complex z); long double complex cacosl(long double complex z);-Description
+Description
The cacos functions compute the complex arc cosine of z, with branch cuts outside the interval [-1, +1] along the real axis. -
Returns
+Returns
The cacos functions return the complex arc cosine value, in the range of a strip mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the real axis. +
7.3.5.2 The casin functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9011,19 +9221,20 @@ unsigned long long int float complex casinf(float complex z); long double complex casinl(long double complex z);-Description
+Description
The casin functions compute the complex arc sine of z, with branch cuts outside the interval [-1, +1] along the real axis. -
Returns
+Returns
The casin functions return the complex arc sine value, in the range of a strip mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2] along the real axis. +
7.3.5.3 The catan functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9031,18 +9242,19 @@ unsigned long long int float complex catanf(float complex z); long double complex catanl(long double complex z);-Description
+Description
The catan functions compute the complex arc tangent of z, with branch cuts outside the interval [-i, +i] along the imaginary axis. -
Returns
+Returns
The catan functions return the complex arc tangent value, in the range of a strip mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2] along the real axis. +
7.3.5.4 The ccos functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9050,15 +9262,16 @@ unsigned long long int float complex ccosf(float complex z); long double complex ccosl(long double complex z);-Description
+Description
The ccos functions compute the complex cosine of z. -
Returns
+Returns
The ccos functions return the complex cosine value. +
7.3.5.5 The csin functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9066,16 +9279,17 @@ unsigned long long int float complex csinf(float complex z); long double complex csinl(long double complex z);-Description
+Description
The csin functions compute the complex sine of z. -
Returns
+Returns
The csin functions return the complex sine value. +
7.3.5.6 The ctan functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9083,17 +9297,19 @@ unsigned long long int float complex ctanf(float complex z); long double complex ctanl(long double complex z);-Description
+Description
The ctan functions compute the complex tangent of z. -
Returns
+Returns
The ctan functions return the complex tangent value. +
7.3.6 Hyperbolic functions
+7.3.6.1 The cacosh functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9101,18 +9317,19 @@ unsigned long long int float complex cacoshf(float complex z); long double complex cacoshl(long double complex z);-Description
+Description
The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch cut at values less than 1 along the real axis. -
Returns
+Returns
The cacosh functions return the complex arc hyperbolic cosine value, in the range of a half-strip of non-negative values along the real axis and in the interval [-ipi , +ipi ] along the imaginary axis. +
7.3.6.2 The casinh functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9120,19 +9337,20 @@ unsigned long long int float complex casinhf(float complex z); long double complex casinhl(long double complex z);-Description
+Description
The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts outside the interval [-i, +i] along the imaginary axis. -
Returns
+Returns
The casinh functions return the complex arc hyperbolic sine value, in the range of a strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2] along the imaginary axis. +
7.3.6.3 The catanh functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9140,18 +9358,19 @@ unsigned long long int float complex catanhf(float complex z); long double complex catanhl(long double complex z);-Description
+Description
The catanh functions compute the complex arc hyperbolic tangent of z, with branch cuts outside the interval [-1, +1] along the real axis. -
Returns
+Returns
The catanh functions return the complex arc hyperbolic tangent value, in the range of a strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2] along the imaginary axis. +
7.3.6.4 The ccosh functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9159,15 +9378,16 @@ unsigned long long int float complex ccoshf(float complex z); long double complex ccoshl(long double complex z);-Description
+Description
The ccosh functions compute the complex hyperbolic cosine of z. -
Returns
+Returns
The ccosh functions return the complex hyperbolic cosine value. +
7.3.6.5 The csinh functions
-Synopsis
+Synopsis
@@ -9176,15 +9396,16 @@ unsigned long long int float complex csinhf(float complex z); long double complex csinhl(long double complex z);-Description
+Description
The csinh functions compute the complex hyperbolic sine of z. -
Returns
+Returns
The csinh functions return the complex hyperbolic sine value. +
7.3.6.6 The ctanh functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9192,17 +9413,19 @@ unsigned long long int float complex ctanhf(float complex z); long double complex ctanhl(long double complex z);-Description
+Description
The ctanh functions compute the complex hyperbolic tangent of z. -
Returns
+Returns
The ctanh functions return the complex hyperbolic tangent value. +
7.3.7 Exponential and logarithmic functions
+7.3.7.1 The cexp functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9210,15 +9433,16 @@ unsigned long long int float complex cexpf(float complex z); long double complex cexpl(long double complex z);-Description
+Description
The cexp functions compute the complex base-e exponential of z. -
Returns
+Returns
The cexp functions return the complex base-e exponential value. +
7.3.7.2 The clog functions
-Synopsis
+Synopsis
@@ -9227,20 +9451,22 @@ unsigned long long int float complex clogf(float complex z); long double complex clogl(long double complex z);-Description
+Description
The clog functions compute the complex natural (base-e) logarithm of z, with a branch cut along the negative real axis. -
Returns
+Returns
The clog functions return the complex natural logarithm value, in the range of a strip mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the imaginary axis. +
7.3.8 Power and absolute-value functions
+7.3.8.1 The cabs functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9248,16 +9474,17 @@ unsigned long long int float cabsf(float complex z); long double cabsl(long double complex z);-Description
+Description
The cabs functions compute the complex absolute value (also called norm, modulus, or magnitude) of z. -
Returns
+Returns
The cabs functions return the complex absolute value. +
7.3.8.2 The cpow functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9266,17 +9493,18 @@ unsigned long long int long double complex cpowl(long double complex x, long double complex y);-Description
+Description
The cpow functions compute the complex power function xy , with a branch cut for the first parameter along the negative real axis. -
Returns
+Returns
The cpow functions return the complex power function value. +
7.3.8.3 The csqrt functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9284,19 +9512,21 @@ unsigned long long int float complex csqrtf(float complex z); long double complex csqrtl(long double complex z);-Description
+Description
The csqrt functions compute the complex square root of z, with a branch cut along the negative real axis. -
Returns
+Returns
The csqrt functions return the complex square root value, in the range of the right half- plane (including the imaginary axis). +
7.3.9 Manipulation functions
+7.3.9.1 The carg functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9304,16 +9534,17 @@ unsigned long long int float cargf(float complex z); long double cargl(long double complex z);-Description
+Description
The carg functions compute the argument (also called phase angle) of z, with a branch cut along the negative real axis. -
Returns
+Returns
The carg functions return the value of the argument in the interval [-pi , +pi ]. +
7.3.9.2 The cimag functions
-Synopsis
+Synopsis
@@ -9322,19 +9553,20 @@ unsigned long long int float cimagf(float complex z); long double cimagl(long double complex z);-Description
+Description
The cimag functions compute the imaginary part of z.170) -
Returns
+Returns
The cimag functions return the imaginary part value (as a real). -
footnotes
+Footnotes
170) For a variable z of complex type, z == creal(z) + cimag(z)*I. +
7.3.9.3 The conj functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9342,16 +9574,17 @@ unsigned long long int float complex conjf(float complex z); long double complex conjl(long double complex z);-Description
+Description
The conj functions compute the complex conjugate of z, by reversing the sign of its imaginary part. -
Returns
+Returns
The conj functions return the complex conjugate value. +
7.3.9.4 The cproj functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9359,7 +9592,7 @@ unsigned long long int float complex cprojf(float complex z); long double complex cprojl(long double complex z);-Description
+Description
The cproj functions compute a projection of z onto the Riemann sphere: z projects to z except that all complex infinities (even those with one infinite part and one NaN part) @@ -9368,7 +9601,7 @@ unsigned long long int
INFINITY + I * copysign(0.0, cimag(z))-Returns
+Returns
The cproj functions return the value of the projection onto the Riemann sphere. @@ -9377,8 +9610,9 @@ unsigned long long int +
7.3.9.5 The creal functions
-Synopsis
+Synopsis
#include <complex.h> @@ -9386,10 +9620,10 @@ unsigned long long int float crealf(float complex z); long double creall(long double complex z);-Description
+Description
The creal functions compute the real part of z.171) -
Returns
+Returns
The creal functions return the real part value. @@ -9398,11 +9632,12 @@ unsigned long long int -
footnotes
+Footnotes
171) For a variable z of complex type, z == creal(z) + cimag(z)*I. -
7.4 Character handling
+Contents +
7.4 Character handling <ctype.h>
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 @@ -9418,7 +9653,7 @@ unsigned long long int characters.173) All letters and digits are printing characters.
Forward references: EOF (7.19.1), localization (7.11). -
footnotes
+Footnotes
172) See ''future library directions'' (7.26.2).
173) In an implementation that uses the seven-bit US ASCII character set, the printing characters are those @@ -9426,30 +9661,33 @@ unsigned long long int 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
-Synopsis
+Synopsis
#include <ctype.h> int isalnum(int c);-Description
+Description
The isalnum function tests for any character for which isalpha or isdigit is true. +
7.4.1.2 The isalpha function
-Synopsis
+Synopsis
#include <ctype.h> int isalpha(int c);-Description
+Description
The isalpha function tests for any character for which isupper or islower is true, or any character that is one of a locale-specific set of alphabetic characters for which @@ -9460,19 +9698,20 @@ unsigned long long int none of iscntrl, isdigit, ispunct, or isspace is true.174) In the "C" locale, isalpha returns true only for the characters for which isupper or islower is true. -
footnotes
+Footnotes
174) The functions islower and isupper test true or false separately for each of these additional characters; all four combinations are possible. +
7.4.1.3 The isblank function
-Synopsis
+Synopsis
#include <ctype.h> int isblank(int c);-Description
+Description
The isblank function tests for any character that is a standard blank character or is one of a locale-specific set of characters for which isspace is true and that is used to @@ -9480,30 +9719,33 @@ unsigned long long int space (' '), and horizontal tab ('\t'). In the "C" locale, isblank returns true only for the standard blank characters. +
7.4.1.4 The iscntrl function
-Synopsis
+Synopsis
#include <ctype.h> int iscntrl(int c);-Description
+Description
The iscntrl function tests for any control character. +
7.4.1.5 The isdigit function
-Synopsis
+Synopsis
#include <ctype.h> int isdigit(int c);-Description
+Description
The isdigit function tests for any decimal-digit character (as defined in 5.2.1). +
7.4.1.6 The isgraph function
-Synopsis
+Synopsis
#include <ctype.h> @@ -9514,57 +9756,61 @@ unsigned long long int --Description
+Description
The isgraph function tests for any printing character except space (' '). +
7.4.1.7 The islower function
-Synopsis
+Synopsis
#include <ctype.h> int islower(int c);-Description
+Description
The islower function tests for any character that is a lowercase letter or is one of a locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or isspace is true. In the "C" locale, islower returns true only for the lowercase letters (as defined in 5.2.1). +
7.4.1.8 The isprint function
-Synopsis
+Synopsis
#include <ctype.h> int isprint(int c);-Description
+Description
The isprint function tests for any printing character including space (' '). +
7.4.1.9 The ispunct function
-Synopsis
+Synopsis
#include <ctype.h> int ispunct(int c);-Description
+Description
The ispunct function tests for any printing character that is one of a locale-specific set of punctuation characters for which neither isspace nor isalnum is true. In the "C" locale, ispunct returns true for every printing character for which neither isspace nor isalnum is true. +
7.4.1.10 The isspace function
-Synopsis
+Synopsis
#include <ctype.h> int isspace(int c);-Description
+Description
The isspace function tests for any character that is a standard white-space character or is one of a locale-specific set of characters for which isalnum is false. The standard @@ -9573,44 +9819,48 @@ unsigned long long int ('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v'). In the "C" locale, isspace returns true only for the standard white-space characters. +
7.4.1.11 The isupper function
-Synopsis
+Synopsis
#include <ctype.h> int isupper(int c);-Description
+Description
The isupper function tests for any character that is an uppercase letter or is one of a locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or isspace is true. In the "C" locale, isupper returns true only for the uppercase letters (as defined in 5.2.1). +
7.4.1.12 The isxdigit function
-Synopsis
+Synopsis
#include <ctype.h> int isxdigit(int c);-Description
+Description
The isxdigit function tests for any hexadecimal-digit character (as defined in 6.4.4.1). +
7.4.2 Character case mapping functions
+7.4.2.1 The tolower function
-Synopsis
+Synopsis
#include <ctype.h> int tolower(int c);-Description
+Description
The tolower function converts an uppercase letter to a corresponding lowercase letter. -
Returns
+Returns
If the argument is a character for which isupper is true and there are one or more corresponding characters, as specified by the current locale, for which islower is true, @@ -9618,17 +9868,18 @@ unsigned long long int for any given locale); otherwise, the argument is returned unchanged. +
7.4.2.2 The toupper function
-Synopsis
+Synopsis
#include <ctype.h> int toupper(int c);-Description
+Description
The toupper function converts a lowercase letter to a corresponding uppercase letter. -
Returns
+Returns
If the argument is a character for which islower is true and there are one or more corresponding characters, as specified by the current locale, for which isupper is true, @@ -9636,7 +9887,8 @@ unsigned long long int for any given locale); otherwise, the argument is returned unchanged. -
7.5 Errors
+Contents +
7.5 Errors <errno.h>
The header <errno.h> defines several macros, all relating to the reporting of error conditions. @@ -9671,7 +9923,7 @@ unsigned long long int -
footnotes
+Footnotes
175) The macro errno need not be the identifier of an object. It might expand to a modifiable lvalue resulting from a function call (for example, *errno()). @@ -9683,7 +9935,8 @@ unsigned long long int
177) See ''future library directions'' (7.26.3). -
7.6 Floating-point environment
+Contents +
7.6 Floating-point environment <fenv.h>
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 @@ -9777,7 +10030,7 @@ unsigned long long int FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may also be specified by the implementation. -
footnotes
+Footnotes
178) This header is designed to support the floating-point exception status flags and directed-rounding control modes required by IEC 60559, and other similar floating-point state information. Also it is designed to facilitate code portability among all systems. @@ -9798,14 +10051,15 @@ unsigned long long int FLT_ROUNDS, they are not required to do so. +
7.6.1 The FENV_ACCESS pragma
-Synopsis
+Synopsis
#include <fenv.h> #pragma STDC FENV_ACCESS on-off-switch-Description
+Description
The FENV_ACCESS pragma provides a means to inform the implementation when a program might access the floating-point environment to test floating-point status flags or @@ -9851,7 +10105,7 @@ unsigned long long int contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.185) -
footnotes
+Footnotes
184) The purpose of the FENV_ACCESS pragma is to allow certain optimizations that could subvert flag tests and mode changes (e.g., global common subexpression elimination, code motion, and constant folding). In general, if the state of FENV_ACCESS is ''off'', the translator can assume that default @@ -9862,6 +10116,7 @@ unsigned long long int ''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 @@ -9870,7 +10125,7 @@ unsigned long long int FE_OVERFLOW | FE_INEXACT. For other argument values the behavior of these functions is undefined. -
footnotes
+Footnotes
186) The functions fetestexcept, feraiseexcept, and feclearexcept support the basic abstraction of flags that are either set or clear. An implementation may endow floating-point status flags with more information -- for example, the address of the code which first raised the floating- @@ -9878,18 +10133,19 @@ unsigned long long int content of flags. +
7.6.2.1 The feclearexcept function
-Synopsis
+Synopsis
#include <fenv.h> int feclearexcept(int excepts);-Description
+Description
The feclearexcept function attempts to clear the supported floating-point exceptions represented by its argument. -
Returns
+Returns
The feclearexcept function returns zero if the excepts argument is zero or if all the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value. @@ -9897,39 +10153,41 @@ unsigned long long int +
7.6.2.2 The fegetexceptflag function
-Synopsis
+Synopsis
#include <fenv.h> int fegetexceptflag(fexcept_t *flagp, int excepts);-Description
+Description
The fegetexceptflag function attempts to store an implementation-defined representation of the states of the floating-point status flags indicated by the argument excepts in the object pointed to by the argument flagp. -
Returns
+Returns
The fegetexceptflag function returns zero if the representation was successfully stored. Otherwise, it returns a nonzero value. +
7.6.2.3 The feraiseexcept function
-Synopsis
+Synopsis
#include <fenv.h> int feraiseexcept(int excepts);-Description
+Description
The feraiseexcept function attempts to raise the supported floating-point exceptions represented by its argument.187) The order in which these floating-point exceptions are raised is unspecified, except as stated in F.7.6. Whether the feraiseexcept function additionally raises the ''inexact'' floating-point exception whenever it raises the ''overflow'' or ''underflow'' floating-point exception is implementation-defined. -
Returns
+Returns
The feraiseexcept function returns zero if the excepts argument is zero or if all the specified exceptions were successfully raised. Otherwise, it returns a nonzero value. @@ -9939,21 +10197,22 @@ unsigned long long int -
footnotes
+Footnotes
187) The effect is intended to be similar to that of floating-point exceptions raised by arithmetic operations. Hence, enabled traps for floating-point exceptions raised by this function are taken. The specification in F.7.6 is in the same spirit. +
7.6.2.4 The fesetexceptflag function
-Synopsis
+Synopsis
#include <fenv.h> int fesetexceptflag(const fexcept_t *flagp, int excepts);-Description
+Description
The fesetexceptflag function attempts to set the floating-point status flags indicated by the argument excepts to the states stored in the object pointed to by @@ -9961,25 +10220,26 @@ unsigned long long int fegetexceptflag whose second argument represented at least those floating-point exceptions represented by the argument excepts. This function does not raise floating- point exceptions, but only sets the state of the flags. -
Returns
+Returns
The fesetexceptflag function returns zero if the excepts argument is zero or if all the specified flags were successfully set to the appropriate state. Otherwise, it returns a nonzero value. +
7.6.2.5 The fetestexcept function
-Synopsis
+Synopsis
#include <fenv.h> int fetestexcept(int excepts);-Description
+Description
The fetestexcept function determines which of a specified subset of the floating- point exception flags are currently set. The excepts argument specifies the floating- point status flags to be queried.188) -
Returns
+Returns
The fetestexcept function returns the value of the bitwise OR of the floating-point exception macros corresponding to the currently set floating-point exceptions included in @@ -10007,44 +10267,47 @@ unsigned long long int
footnotes
+Footnotes
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
-Synopsis
+Synopsis
#include <fenv.h> int fegetround(void);-Description
+Description
The fegetround function gets the current rounding direction. -
Returns
+Returns
The fegetround function returns the value of the rounding direction macro representing the current rounding direction or a negative value if there is no such rounding direction macro or the current rounding direction is not determinable. +
7.6.3.2 The fesetround function
-Synopsis
+Synopsis
#include <fenv.h> int fesetround(int round);-Description
+Description
The fesetround function establishes the rounding direction represented by its argument round. If the argument is not equal to the value of a rounding direction macro, the rounding direction is not changed. -
Returns
+Returns
The fesetround function returns zero if and only if the requested rounding direction was established. @@ -10070,87 +10333,92 @@ unsigned long long int
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
-Synopsis
+Synopsis
#include <fenv.h> int fegetenv(fenv_t *envp);-Description
+Description
The fegetenv function attempts to store the current floating-point environment in the object pointed to by envp. -
Returns
+Returns
The fegetenv function returns zero if the environment was successfully stored. Otherwise, it returns a nonzero value. +
7.6.4.2 The feholdexcept function
-Synopsis
+Synopsis
#include <fenv.h> int feholdexcept(fenv_t *envp);-Description
+Description
The feholdexcept function saves the current floating-point environment in the object pointed to by envp, clears the floating-point status flags, and then installs a non-stop (continue on floating-point exceptions) mode, if available, for all floating-point exceptions.189) -
Returns
+Returns
The feholdexcept function returns zero if and only if non-stop floating-point exception handling was successfully installed. -
footnotes
+Footnotes
189) IEC 60559 systems have a default non-stop mode, and typically at least one other mode for trap handling or aborting; if the system provides only the non-stop mode then installing it is trivial. For such systems, the feholdexcept function can be used in conjunction with the feupdateenv function to write routines that hide spurious floating-point exceptions from their callers. +
7.6.4.3 The fesetenv function
-Synopsis
+Synopsis
#include <fenv.h> int fesetenv(const fenv_t *envp);-Description
+Description
The fesetenv function attempts to establish the floating-point environment represented by the object pointed to by envp. The argument envp shall point to an object set by a call to fegetenv or feholdexcept, or equal a floating-point environment macro. Note that fesetenv merely installs the state of the floating-point status flags represented through its argument, and does not raise these floating-point exceptions. -
Returns
+Returns
The fesetenv function returns zero if the environment was successfully established. Otherwise, it returns a nonzero value. +
7.6.4.4 The feupdateenv function
-Synopsis
+Synopsis
#include <fenv.h> int feupdateenv(const fenv_t *envp);-Description
+Description
The feupdateenv function attempts to save the currently raised floating-point exceptions in its automatic storage, install the floating-point environment represented by the object pointed to by envp, and then raise the saved floating-point exceptions. The argument envp shall point to an object set by a call to feholdexcept or fegetenv, or equal a floating-point environment macro. -
Returns
+Returns
The feupdateenv function returns zero if all the actions were successfully carried out. Otherwise, it returns a nonzero value. @@ -10181,7 +10449,8 @@ unsigned long long int }
Contents +
The header <float.h> defines several macros that expand to various limits and parameters of the standard floating-point types. @@ -10190,7 +10459,8 @@ unsigned long long int in 5.2.4.2.2. -
Contents +
The header <inttypes.h> includes the header <stdint.h> and extends it with additional facilities provided by hosted implementations. @@ -10206,10 +10476,11 @@ unsigned long long int
Forward references: integer types <stdint.h> (7.18), formatted input/output functions (7.19.6), formatted wide character input/output functions (7.24.2). -
Footnotes
190) See ''future library directions'' (7.26.4). +
Each of the following object-like macros191) expands to a character string literal @@ -10273,7 +10544,7 @@ unsigned long long int -
Footnotes
191) C++ implementations should define these macros only when __STDC_FORMAT_MACROS is defined before <inttypes.h> is included. @@ -10282,16 +10553,18 @@ unsigned long long int same. +
Synopsis
#include <inttypes.h>
intmax_t imaxabs(intmax_t j);
-Description
The imaxabs function computes the absolute value of an integer j. If the result cannot be represented, the behavior is undefined.193) @@ -10299,34 +10572,36 @@ unsigned long long int -
Returns
The imaxabs function returns the absolute value. -
Footnotes
193) The absolute value of the most negative number cannot be represented in two's complement. +
Synopsis
#include <inttypes.h>
imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
-Description
The imaxdiv function computes numer / denom and numer % denom in a single operation. -
Returns
The imaxdiv function returns a structure of type imaxdiv_t comprising both the quotient and the remainder. The structure shall contain (in either order) the members quot (the quotient) and rem (the remainder), each of which has type intmax_t. If either part of the result cannot be represented, the behavior is undefined. +
Synopsis
#include <inttypes.h>
@@ -10335,12 +10610,12 @@ unsigned long long int
uintmax_t strtoumax(const char * restrict nptr,
char ** restrict endptr, int base);
-Description
The strtoimax and strtoumax functions are equivalent to the strtol, strtoll, strtoul, and strtoull functions, except that the initial portion of the string is converted to intmax_t and uintmax_t representation, respectively. -
Returns
The strtoimax and strtoumax functions return the converted value, if any. If no conversion could be performed, zero is returned. If the correct value is outside the range @@ -10351,8 +10626,9 @@ unsigned long long int (7.20.1.4). +
Synopsis
#include <stddef.h> // for wchar_t
@@ -10362,12 +10638,12 @@ unsigned long long int
uintmax_t wcstoumax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
-Description
The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll, wcstoul, and wcstoull functions except that the initial portion of the wide string is converted to intmax_t and uintmax_t representation, respectively. -
Returns
The wcstoimax function returns the converted value, if any. If no conversion could be performed, zero is returned. If the correct value is outside the range of representable @@ -10378,7 +10654,8 @@ unsigned long long int (7.24.4.1.2). -
Contents +
The header <iso646.h> defines the following eleven macros (on the left) that expand to the corresponding tokens (on the right): @@ -10397,7 +10674,8 @@ unsigned long long int xor_eq ^= -
Contents +
The header <limits.h> defines several macros that expand to various limits and parameters of the standard integer types. @@ -10406,7 +10684,8 @@ unsigned long long int in 5.2.4.2.1. -
Contents +
The header <locale.h> declares two functions, one type, and defines several macros.
@@ -10460,22 +10739,24 @@ unsigned long long int with the characters LC_ and an uppercase letter,195) may also be specified by the implementation. -
Footnotes
194) ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C.
195) See ''future library directions'' (7.26.5). +
Synopsis
#include <locale.h>
char *setlocale(int category, const char *locale);
-Description
The setlocale function selects the appropriate portion of the program's locale as specified by the category and locale arguments. The setlocale function may be @@ -10503,7 +10784,7 @@ unsigned long long int is executed.
The implementation shall behave as if no library function calls the setlocale function. -
Returns
If a pointer to a string is given for locale and the selection can be honored, the setlocale function returns a pointer to the string associated with the specified @@ -10523,7 +10804,7 @@ unsigned long long int (7.20.8), numeric conversion functions (7.20.1), the strcoll function (7.21.4.3), the strftime function (7.23.3.5), the strxfrm function (7.21.4.5). -
Footnotes
196) The only functions in 7.4 whose behavior is not affected by the current locale are isdigit and isxdigit. @@ -10531,16 +10812,18 @@ unsigned long long int locale when category has the value LC_ALL. +
Synopsis
#include <locale.h>
struct lconv *localeconv(void);
-Description
The localeconv function sets the components of an object with type struct lconv with values appropriate for the formatting of numeric quantities (monetary and otherwise) @@ -10696,7 +10979,7 @@ unsigned long long int
The implementation shall behave as if no library function calls the localeconv function. -
Returns
The localeconv function returns a pointer to the filled-in object. The structure pointed to by the return value shall not be modified by the program, but may be @@ -10766,7 +11049,8 @@ unsigned long long int -
Contents +
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 @@ -10876,7 +11160,7 @@ unsigned long long int shall define the macros FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in <fenv.h>. -
Footnotes
198) Particularly on systems with wide expression evaluation, a <math.h> function might pass arguments and return values in wider format than the synopsis prototype indicates. @@ -10894,6 +11178,7 @@ unsigned long long int substantially slower. +
The behavior of each of the functions in <math.h> is specified for all representable @@ -10938,7 +11223,7 @@ unsigned long long int math_errhandling & MATH_ERREXCEPT is nonzero, whether the ''underflow'' floating-point exception is raised is implementation-defined. -
Footnotes
203) In an implementation that supports infinities, this allows an infinity as an argument to be a domain error if the mathematical domain of the function does not include the infinity. @@ -10946,14 +11231,15 @@ unsigned long long int also ''flush-to-zero'' underflow. +
Synopsis
#include <math.h>
#pragma STDC FP_CONTRACT on-off-switch
-Description
The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the state is ''off'') the implementation to contract expressions (6.5). Each pragma can occur @@ -10973,25 +11259,27 @@ unsigned long long int +
In the synopses in this subclause, real-floating indicates that the argument shall be an expression of real floating type. +
Synopsis
#include <math.h>
int fpclassify(real-floating x);
-Description
The fpclassify macro classifies its argument value as NaN, infinite, normal, subnormal, zero, or into another implementation-defined category. First, an argument represented in a format wider than its semantic type is converted to its semantic type. Then classification is based on the type of the argument.205) -
Returns
The fpclassify macro returns the value of the number classification macro appropriate to the value of its argument. @@ -11005,20 +11293,21 @@ unsigned long long int -
Footnotes
205) Since an expression can be evaluated with more range and precision than its type has, it is important to know the type that classification is based on. For example, a normal long double value might become subnormal when converted to double, and zero when converted to float. +
Synopsis
#include <math.h>
int isfinite(real-floating x);
-Description
The isfinite macro determines whether its argument has a finite value (zero, subnormal, or normal, and not infinite or NaN). First, an argument represented in a @@ -11029,51 +11318,54 @@ unsigned long long int -
Returns
The isfinite macro returns a nonzero value if and only if its argument has a finite value. +
Synopsis
#include <math.h>
int isinf(real-floating x);
-Description
The isinf macro determines whether its argument value is an infinity (positive or negative). First, an argument represented in a format wider than its semantic type is converted to its semantic type. Then determination is based on the type of the argument. -
Returns
The isinf macro returns a nonzero value if and only if its argument has an infinite value. +
Synopsis
#include <math.h>
int isnan(real-floating x);
-Description
The isnan macro determines whether its argument value is a NaN. First, an argument represented in a format wider than its semantic type is converted to its semantic type. Then determination is based on the type of the argument.206) -
Returns
The isnan macro returns a nonzero value if and only if its argument has a NaN value. -
Footnotes
206) For the isnan macro, the type for determination does not matter unless the implementation supports NaNs in the evaluation type but not in the semantic type. +
Synopsis
#include <math.h>
@@ -11084,41 +11376,44 @@ unsigned long long int
-Description
+Description
The isnormal macro determines whether its argument value is normal (neither zero,
subnormal, infinite, nor NaN). First, an argument represented in a format wider than its
semantic type is converted to its semantic type. Then determination is based on the type
of the argument.
-
Returns
+Returns
The isnormal macro returns a nonzero value if and only if its argument has a normal
value.
+
7.12.3.6 The signbit macro
-Synopsis
+Synopsis
#include <math.h>
int signbit(real-floating x);
-Description
+Description
The signbit macro determines whether the sign of its argument value is negative.207)
-
Returns
+Returns
The signbit macro returns a nonzero value if and only if the sign of its argument value
is negative.
-
footnotes
+Footnotes
207) The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
unsigned, it is treated as positive.
+
7.12.4 Trigonometric functions
+7.12.4.1 The acos functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11126,11 +11421,11 @@ unsigned long long int
float acosf(float x);
long double acosl(long double x);
-Description
+Description
The acos functions compute the principal value of the arc cosine of x. A domain error
occurs for arguments not in the interval [-1, +1].
-
Returns
+Returns
The acos functions return arccos x in the interval [0, pi ] radians.
@@ -11139,8 +11434,9 @@ unsigned long long int
+
7.12.4.2 The asin functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11148,16 +11444,17 @@ unsigned long long int
float asinf(float x);
long double asinl(long double x);
-Description
+Description
The asin functions compute the principal value of the arc sine of x. A domain error
occurs for arguments not in the interval [-1, +1].
-
Returns
+Returns
The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
+
7.12.4.3 The atan functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11165,15 +11462,16 @@ unsigned long long int
float atanf(float x);
long double atanl(long double x);
-Description
+Description
The atan functions compute the principal value of the arc tangent of x.
-
Returns
+Returns
The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
+
7.12.4.4 The atan2 functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11181,18 +11479,19 @@ unsigned long long int
float atan2f(float y, float x);
long double atan2l(long double y, long double x);
-Description
+Description
The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
arguments to determine the quadrant of the return value. A domain error may occur if
both arguments are zero.
-
Returns
+Returns
The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
+
7.12.4.5 The cos functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11200,15 +11499,16 @@ unsigned long long int
float cosf(float x);
long double cosl(long double x);
-Description
+Description
The cos functions compute the cosine of x (measured in radians).
-
Returns
+Returns
The cos functions return cos x.
+
7.12.4.6 The sin functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11216,15 +11516,16 @@ unsigned long long int
float sinf(float x);
long double sinl(long double x);
-Description
+Description
The sin functions compute the sine of x (measured in radians).
-
Returns
+Returns
The sin functions return sin x.
+
7.12.4.7 The tan functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11232,18 +11533,20 @@ unsigned long long int
float tanf(float x);
long double tanl(long double x);
-Description
+Description
The tan functions return the tangent of x (measured in radians).
-
Returns
+Returns
The tan functions return tan x.
+
7.12.5 Hyperbolic functions
+7.12.5.1 The acosh functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11251,16 +11554,17 @@ unsigned long long int
float acoshf(float x);
long double acoshl(long double x);
-Description
+Description
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
error occurs for arguments less than 1.
-
Returns
+Returns
The acosh functions return arcosh x in the interval [0, +(inf)].
+
7.12.5.2 The asinh functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11268,15 +11572,16 @@ unsigned long long int
float asinhf(float x);
long double asinhl(long double x);
-Description
+Description
The asinh functions compute the arc hyperbolic sine of x.
-
Returns
+Returns
The asinh functions return arsinh x.
+
7.12.5.3 The atanh functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11284,18 +11589,19 @@ unsigned long long int
float atanhf(float x);
long double atanhl(long double x);
-Description
+Description
The atanh functions compute the arc hyperbolic tangent of x. A domain error occurs
for arguments not in the interval [-1, +1]. A range error may occur if the argument
equals -1 or +1.
-
Returns
+Returns
The atanh functions return artanh x.
+
7.12.5.4 The cosh functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11303,16 +11609,17 @@ unsigned long long int
float coshf(float x);
long double coshl(long double x);
-Description
+Description
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
magnitude of x is too large.
-
Returns
+Returns
The cosh functions return cosh x.
+
7.12.5.5 The sinh functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11320,16 +11627,17 @@ unsigned long long int
float sinhf(float x);
long double sinhl(long double x);
-Description
+Description
The sinh functions compute the hyperbolic sine of x. A range error occurs if the
magnitude of x is too large.
-
Returns
+Returns
The sinh functions return sinh x.
+
7.12.5.6 The tanh functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11337,18 +11645,20 @@ unsigned long long int
float tanhf(float x);
long double tanhl(long double x);
-Description
+Description
The tanh functions compute the hyperbolic tangent of x.
-
Returns
+Returns
The tanh functions return tanh x.
+
7.12.6 Exponential and logarithmic functions
+7.12.6.1 The exp functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11356,16 +11666,17 @@ unsigned long long int
float expf(float x);
long double expl(long double x);
-Description
+Description
The exp functions compute the base-e exponential of x. A range error occurs if the
magnitude of x is too large.
-
Returns
+Returns
The exp functions return ex.
+
7.12.6.2 The exp2 functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11373,16 +11684,17 @@ unsigned long long int
float exp2f(float x);
long double exp2l(long double x);
-Description
+Description
The exp2 functions compute the base-2 exponential of x. A range error occurs if the
magnitude of x is too large.
-
Returns
+Returns
The exp2 functions return 2x.
+
7.12.6.3 The expm1 functions
-Synopsis
+Synopsis
@@ -11391,20 +11703,21 @@ unsigned long long int
float expm1f(float x);
long double expm1l(long double x);
-Description
+Description
The expm1 functions compute the base-e exponential of the argument, minus 1. A range
error occurs if x is too large.208)
-
Returns
+Returns
The expm1 functions return ex - 1.
-
footnotes
+Footnotes
208) For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
+
7.12.6.4 The frexp functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11412,18 +11725,19 @@ unsigned long long int
float frexpf(float value, int *exp);
long double frexpl(long double value, int *exp);
-Description
+Description
The frexp functions break a floating-point number into a normalized fraction and an
integral power of 2. They store the integer in the int object pointed to by exp.
-
Returns
+Returns
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 2*exp . If value is zero, both parts of the result are zero.
+
7.12.6.5 The ilogb functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11431,7 +11745,7 @@ unsigned long long int
int ilogbf(float x);
int ilogbl(long double x);
-Description
+Description
The ilogb functions extract the exponent of x as a signed int value. If x is zero they
compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is
@@ -11444,13 +11758,14 @@ unsigned long long int
-
Returns
+Returns
The ilogb functions return the exponent of x as a signed int value.
Forward references: the logb functions (7.12.6.11).
+
7.12.6.6 The ldexp functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11458,16 +11773,17 @@ unsigned long long int
float ldexpf(float x, int exp);
long double ldexpl(long double x, int exp);
-Description
+Description
The ldexp functions multiply a floating-point number by an integral power of 2. A
range error may occur.
-
Returns
+Returns
The ldexp functions return x 2exp .
+
7.12.6.7 The log functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11475,16 +11791,17 @@ unsigned long long int
float logf(float x);
long double logl(long double x);
-Description
+Description
The log functions compute the base-e (natural) logarithm of x. A domain error occurs if
the argument is negative. A range error may occur if the argument is zero.
-
Returns
+Returns
The log functions return loge x.
+
7.12.6.8 The log10 functions
-Synopsis
+Synopsis
@@ -11493,16 +11810,17 @@ unsigned long long int
float log10f(float x);
long double log10l(long double x);
-Description
+Description
The log10 functions compute the base-10 (common) logarithm of x. A domain error
occurs if the argument is negative. A range error may occur if the argument is zero.
-
Returns
+Returns
The log10 functions return log10 x.
+
7.12.6.9 The log1p functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11510,21 +11828,22 @@ unsigned long long int
float log1pf(float x);
long double log1pl(long double x);
-Description
+Description
The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.209)
A domain error occurs if the argument is less than -1. A range error may occur if the
argument equals -1.
-
Returns
+Returns
The log1p functions return loge (1 + x).
-
footnotes
+Footnotes
209) For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
+
7.12.6.10 The log2 functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11532,11 +11851,11 @@ unsigned long long int
float log2f(float x);
long double log2l(long double x);
-Description
+Description
The log2 functions compute the base-2 logarithm of x. A domain error occurs if the
argument is less than zero. A range error may occur if the argument is zero.
-
Returns
+Returns
The log2 functions return log2 x.
@@ -11545,8 +11864,9 @@ unsigned long long int
+
7.12.6.11 The logb functions
-Synopsis
+Synopsis
#include <math.h>
@@ -11554,7 +11874,7 @@ unsigned long long int
float logbf(float x);
long double logbl(long double x);
-Description
+Description
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
@@ -11563,12 +11883,13 @@ unsigned long long int
1 <= x FLT_RADIX-logb(x) < FLT_RADIX
A domain error or range error may occur if the argument is zero.
-Returns
The logb functions return the signed exponent of x. +
Synopsis
#include <math.h>
@@ -11576,18 +11897,19 @@ unsigned long long int
float modff(float value, float *iptr);
long double modfl(long double value, long double *iptr);
-Description
The modf functions break the argument value into integral and fractional parts, each of which has the same type and sign as the argument. They store the integral part (in floating-point format) in the object pointed to by iptr. -
Returns
The modf functions return the signed fractional part of value. +
Synopsis
#include <math.h>
@@ -11598,18 +11920,20 @@ unsigned long long int
float scalblnf(float x, long int n);
long double scalblnl(long double x, long int n);
-Description
The scalbn and scalbln functions compute x FLT_RADIXn efficiently, not normally by computing FLT_RADIXn explicitly. A range error may occur. -
Returns
The scalbn and scalbln functions return x FLT_RADIXn . +
Synopsis
#include <math.h>
@@ -11617,15 +11941,16 @@ unsigned long long int
float cbrtf(float x);
long double cbrtl(long double x);
-Description
The cbrt functions compute the real cube root of x. -
Returns
The cbrt functions return x1/3. +
Synopsis
#include <math.h>
@@ -11633,16 +11958,17 @@ unsigned long long int
float fabsf(float x);
long double fabsl(long double x);
-Description
The fabs functions compute the absolute value of a floating-point number x. -
Returns
The fabs functions return | x |. +
Synopsis
#include <math.h>
@@ -11650,17 +11976,18 @@ unsigned long long int
float hypotf(float x, float y);
long double hypotl(long double x, long double y);
-Description
The hypot functions compute the square root of the sum of the squares of x and y, without undue overflow or underflow. A range error may occur.
-
Returns
The hypot functions return (sqrt)(x2 + y2). +
Synopsis
#include <math.h>
@@ -11668,18 +11995,19 @@ unsigned long long int
float powf(float x, float y);
long double powl(long double x, long double y);
-Description
The pow functions compute x raised to the power y. A domain error occurs if x is finite and negative and y is finite and not an integer value. A range error may occur. A domain error may occur if x is zero and y is zero. A domain error or range error may occur if x is zero and y is less than zero. -
Returns
The pow functions return xy. +
Synopsis
@@ -11688,18 +12016,20 @@ unsigned long long int
float sqrtf(float x);
long double sqrtl(long double x);
-Description
The sqrt functions compute the nonnegative square root of x. A domain error occurs if the argument is less than zero. -
Returns
The sqrt functions return (sqrt)(x). +
Synopsis
#include <math.h>
@@ -11707,10 +12037,10 @@ unsigned long long int
float erff(float x);
long double erfl(long double x);
-Description
The erf functions compute the error function of x. -
Returns
The erf functions return
@@ -11719,8 +12049,9 @@ unsigned long long int
(sqrt)(pi) 0
+Synopsis
#include <math.h>
@@ -11728,11 +12059,11 @@ unsigned long long int
float erfcf(float x);
long double erfcl(long double x);
-Description
The erfc functions compute the complementary error function of x. A range error occurs if x is too large. -
Returns
The erfc functions return
@@ -11742,8 +12073,9 @@ unsigned long long int+
Synopsis
#include <math.h>
@@ -11751,17 +12083,18 @@ unsigned long long int
float lgammaf(float x);
long double lgammal(long double x);
-Description
The lgamma functions compute the natural logarithm of the absolute value of gamma of x. A range error occurs if x is too large. A range error may occur if x is a negative integer or zero. -
Returns
The lgamma functions return loge | (Gamma)(x) |. +
Synopsis
#include <math.h>
@@ -11769,19 +12102,21 @@ unsigned long long int
float tgammaf(float x);
long double tgammal(long double x);
-Description
The tgamma functions compute the gamma function of x. A domain error or range error may occur if x is a negative integer or zero. A range error may occur if the magnitude of x is too large or too small. -
Returns
The tgamma functions return (Gamma)(x). +
Synopsis
#include <math.h>
@@ -11789,16 +12124,17 @@ unsigned long long int
float ceilf(float x);
long double ceill(long double x);
-Description
The ceil functions compute the smallest integer value not less than x. -
Returns
The ceil functions return [^x^], expressed as a floating-point number. +
Synopsis
#include <math.h>
@@ -11806,15 +12142,16 @@ unsigned long long int
float floorf(float x);
long double floorl(long double x);
-Description
The floor functions compute the largest integer value not greater than x. -
Returns
The floor functions return [_x_], expressed as a floating-point number. +
Synopsis
#include <math.h>
@@ -11822,17 +12159,18 @@ unsigned long long int
float nearbyintf(float x);
long double nearbyintl(long double x);
-Description
The nearbyint functions round their argument to an integer value in floating-point format, using the current rounding direction and without raising the ''inexact'' floating- point exception. -
Returns
The nearbyint functions return the rounded integer value. +
Synopsis
#include <math.h>
@@ -11840,18 +12178,19 @@ unsigned long long int
float rintf(float x);
long double rintl(long double x);
-Description
The rint functions differ from the nearbyint functions (7.12.9.3) only in that the rint functions may raise the ''inexact'' floating-point exception if the result differs in value from the argument. -
Returns
The rint functions return the rounded integer value. +
Synopsis
#include <math.h>
@@ -11862,18 +12201,19 @@ unsigned long long int
long long int llrintf(float x);
long long int llrintl(long double x);
-Description
The lrint and llrint functions round their argument to the nearest integer value, rounding according to the current rounding direction. If the rounded value is outside the range of the return type, the numeric result is unspecified and a domain error or range error may occur. * -
Returns
The lrint and llrint functions return the rounded integer value. +
Synopsis
#include <math.h>
@@ -11881,18 +12221,19 @@ unsigned long long int
float roundf(float x);
long double roundl(long double x);
-Description
The round functions round their argument to the nearest integer value in floating-point format, rounding halfway cases away from zero, regardless of the current rounding direction. -
Returns
The round functions return the rounded integer value. +
Synopsis
#include <math.h>
@@ -11903,18 +12244,19 @@ unsigned long long int
long long int llroundf(float x);
long long int llroundl(long double x);
-Description
The lround and llround functions round their argument to the nearest integer value, rounding halfway cases away from zero, regardless of the current rounding direction. If the rounded value is outside the range of the return type, the numeric result is unspecified and a domain error or range error may occur. -
Returns
The lround and llround functions return the rounded integer value. +
Synopsis
#include <math.h>
@@ -11922,19 +12264,21 @@ unsigned long long int
float truncf(float x);
long double truncl(long double x);
-Description
The trunc functions round their argument to the integer value, in floating format, nearest to but no larger in magnitude than the argument. -
Returns
The trunc functions return the truncated integer value. +
Synopsis
#include <math.h>
@@ -11942,18 +12286,19 @@ unsigned long long int
float fmodf(float x, float y);
long double fmodl(long double x, long double y);
-Description
The fmod functions compute the floating-point remainder of x/y. -
Returns
The fmod functions return the value x - ny, for some integer n such that, if y is nonzero, the result has the same sign as x and magnitude less than the magnitude of y. If y is zero, whether a domain error occurs or the fmod functions return zero is implementation- defined. +
Synopsis
#include <math.h>
@@ -11961,10 +12306,10 @@ unsigned long long int
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
-Description
The remainder functions compute the remainder x REM y required by IEC 60559.210) -
Returns
The remainder functions return x REM y. If y is zero, whether a domain error occurs or the functions return zero is implementation defined. @@ -11974,15 +12319,16 @@ unsigned long long int -
Footnotes
210) ''When y != 0, the remainder r = x REM y is defined regardless of the rounding mode by the mathematical relation r = x - ny, where n is the integer nearest the exact value of x/y; whenever | n - x/y | = 1/2, then n is even. Thus, the remainder is always exact. If r = 0, its sign shall be that of x.'' This definition is applicable for all implementations. +
Synopsis
#include <math.h>
@@ -11991,22 +12337,24 @@ unsigned long long int
long double remquol(long double x, long double y,
int *quo);
-Description
The remquo functions compute the same remainder as the remainder functions. In the object pointed to by quo they store a value whose sign is the sign of x/y and whose magnitude is congruent modulo 2n to the magnitude of the integral quotient of x/y, where n is an implementation-defined integer greater than or equal to 3. -
Returns
The remquo functions return x REM y. If y is zero, the value stored in the object pointed to by quo is unspecified and whether a domain error occurs or the functions return zero is implementation defined. +
Synopsis
#include <math.h>
@@ -12014,19 +12362,20 @@ unsigned long long int
float copysignf(float x, float y);
long double copysignl(long double x, long double y);
-Description
The copysign functions produce a value with the magnitude of x and the sign of y. They produce a NaN (with the sign of y) if x is a NaN. On implementations that represent a signed zero but do not treat negative zero consistently in arithmetic operations, the copysign functions regard the sign of zero as positive. -
Returns
The copysign functions return a value with the magnitude of x and the sign of y. +
Synopsis
#include <math.h>
@@ -12034,7 +12383,7 @@ unsigned long long int
float nanf(const char *tagp);
long double nanl(const char *tagp);
-Description
The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char- sequence)", (char**) NULL); the call nan("") is equivalent to @@ -12042,14 +12391,15 @@ unsigned long long int sequence or an empty string, the call is equivalent to strtod("NAN", (char**) NULL). Calls to nanf and nanl are equivalent to the corresponding calls to strtof and strtold. -
Returns
The nan functions return a quiet NaN, if available, with content indicated through tagp. If the implementation does not support quiet NaNs, the functions return zero.
Forward references: the strtod, strtof, and strtold functions (7.20.1.3). +
Synopsis
#include <math.h>
@@ -12057,14 +12407,14 @@ unsigned long long int
float nextafterf(float x, float y);
long double nextafterl(long double x, long double y);
-Description
The nextafter functions determine the next representable value, in the type of the function, after x in the direction of y, where x and y are first converted to the type of the function.211) The nextafter functions return y if x equals y. A range error may occur if the magnitude of x is the largest finite value representable in the type and the result is infinite or not representable in the type. -
Returns
The nextafter functions return the next representable value in the specified format after x in the direction of y. @@ -12072,13 +12422,14 @@ unsigned long long int -
Footnotes
211) The argument values are converted to the type of the function, even by a macro implementation of the function. +
Synopsis
#include <math.h>
@@ -12086,21 +12437,23 @@ unsigned long long int
float nexttowardf(float x, long double y);
long double nexttowardl(long double x, long double y);
-Description
The nexttoward functions are equivalent to the nextafter functions except that the second parameter has type long double and the functions return y converted to the type of the function if x equals y.212) -
Footnotes
212) The result of the nexttoward functions is determined in the type of the function, without loss of range or precision in a floating second argument. +
Synopsis
#include <math.h>
@@ -12108,7 +12461,7 @@ unsigned long long int
float fdimf(float x, float y);
long double fdiml(long double x, long double y);
-Description
The fdim functions determine the positive difference between their arguments:
@@ -12117,12 +12470,13 @@ unsigned long long int
{+0 if x <= y
A range error may occur.
-Returns
The fdim functions return the positive difference value. +
Synopsis
#include <math.h>
@@ -12134,20 +12488,21 @@ unsigned long long int
-Description
+Description
The fmax functions determine the maximum numeric value of their arguments.213)
-
Returns
+Returns
The fmax functions return the maximum numeric value of their arguments.
-
footnotes
+Footnotes
213) NaN arguments are treated as missing data: if one argument is a NaN and the other numeric, then the
fmax functions choose the numeric value. See F.9.9.2.
+
7.12.12.3 The fmin functions
-Synopsis
+Synopsis
#include <math.h>
@@ -12155,21 +12510,23 @@ unsigned long long int
float fminf(float x, float y);
long double fminl(long double x, long double y);
-Description
+Description
The fmin functions determine the minimum numeric value of their arguments.214)
-
Returns
+Returns
The fmin functions return the minimum numeric value of their arguments.
-
footnotes
+Footnotes
214) The fmin functions are analogous to the fmax functions in their treatment of NaNs.
+
7.12.13 Floating multiply-add
+7.12.13.1 The fma functions
-Synopsis
+Synopsis
#include <math.h>
@@ -12178,12 +12535,12 @@ unsigned long long int
long double fmal(long double x, long double y,
long double z);
-Description
+Description
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.
-
Returns
+Returns
The fma functions return (x y) + z, rounded as one ternary operation.
@@ -12192,6 +12549,7 @@ unsigned long long int
+
7.12.14 Comparison macros
The relational and equality operators support the usual mathematical relationships
@@ -12205,37 +12563,39 @@ unsigned long long int
the synopses in this subclause, real-floating indicates that the argument shall be an
expression of real floating type.
-
footnotes
+Footnotes
215) IEC 60559 requires that the built-in relational operators raise the ''invalid'' floating-point exception if
the operands compare unordered, as an error indicator for programs written without consideration of
NaNs; the result in these cases is false.
+
7.12.14.1 The isgreater macro
-Synopsis
+Synopsis
#include <math.h>
int isgreater(real-floating x, real-floating y);
-Description
+Description
The isgreater macro determines whether its first argument is greater than its second
argument. The value of isgreater(x, y) is always equal to (x) > (y); however,
unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
-
Returns
+Returns
The isgreater macro returns the value of (x) > (y).
+
7.12.14.2 The isgreaterequal macro
-Synopsis
+Synopsis
#include <math.h>
int isgreaterequal(real-floating x, real-floating y);
-Description
+Description
The isgreaterequal macro determines whether its first argument is greater than or
equal to its second argument. The value of isgreaterequal(x, y) is always equal
@@ -12245,52 +12605,55 @@ unsigned long long int
-
Returns
+Returns
The isgreaterequal macro returns the value of (x) >= (y).
+
7.12.14.3 The isless macro
-Synopsis
+Synopsis
#include <math.h>
int isless(real-floating x, real-floating y);
-Description
+Description
The isless macro determines whether its first argument is less than its second
argument. The value of isless(x, y) is always equal to (x) < (y); however,
unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
-
Returns
+Returns
The isless macro returns the value of (x) < (y).
+
7.12.14.4 The islessequal macro
-Synopsis
+Synopsis
#include <math.h>
int islessequal(real-floating x, real-floating y);
-Description
+Description
The islessequal macro determines whether its first argument is less than or equal to
its second argument. The value of islessequal(x, y) is always equal to
(x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered.
-
Returns
+Returns
The islessequal macro returns the value of (x) <= (y).
+
7.12.14.5 The islessgreater macro
-Synopsis
+Synopsis
#include <math.h>
int islessgreater(real-floating x, real-floating y);
-Description
+Description
The islessgreater macro determines whether its first argument is less than or
greater than its second argument. The islessgreater(x, y) macro is similar to
@@ -12298,26 +12661,28 @@ unsigned long long int
the ''invalid'' floating-point exception when x and y are unordered (nor does it evaluate x
and y twice).
-
Returns
+Returns
The islessgreater macro returns the value of (x) < (y) || (x) > (y).
+
7.12.14.6 The isunordered macro
-Synopsis
+Synopsis
#include <math.h>
int isunordered(real-floating x, real-floating y);
-Description
+Description
The isunordered macro determines whether its arguments are unordered.
-
Returns
+Returns
The isunordered macro returns 1 if its arguments are unordered and 0 otherwise.
-
7.13 Nonlocal jumps
+Contents
+
7.13 Nonlocal jumps <setjmp.h>
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)
@@ -12337,30 +12702,32 @@ unsigned long long int
linkage. If a macro definition is suppressed in order to access an actual function, or a
program defines an external identifier with the name setjmp, the behavior is undefined.
-
footnotes
+Footnotes
216) These functions are useful for dealing with unusual conditions encountered in a low-level function of
a program.
+
7.13.1 Save calling environment
+7.13.1.1 The setjmp macro
-Synopsis
+Synopsis
#include <setjmp.h>
int setjmp(jmp_buf env);
-Description
+Description
The setjmp macro saves its calling environment in its jmp_buf argument for later use
by the longjmp function.
-
Returns
+Returns
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
+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. +
Synopsis
#include <setjmp.h>
void longjmp(jmp_buf env, int val);
-Description
The longjmp function restores the environment saved by the most recent invocation of the setjmp macro in the same invocation of the program with the corresponding @@ -12402,7 +12771,7 @@ unsigned long long int invocation of the corresponding setjmp macro that do not have volatile-qualified type and have been changed between the setjmp invocation and longjmp call are indeterminate. -
Returns
After longjmp is completed, program execution continues as if the corresponding invocation of the setjmp macro had just returned the value specified by val. The @@ -12441,14 +12810,15 @@ unsigned long long int } -
Footnotes
217) For example, by executing a return statement or because another longjmp call has caused a transfer to a setjmp invocation in a function earlier in the set of nested calls.
218) This includes, but is not limited to, the floating-point status flags and the state of open files. -
Contents +
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). @@ -12493,22 +12863,24 @@ unsigned long long int -
Footnotes
219) See ''future library directions'' (7.26.9). The names of the signal numbers reflect the following terms (respectively): abort, floating-point exception, illegal instruction, interrupt, segmentation violation, and termination. +
Synopsis
#include <signal.h>
void (*signal(int sig, void (*func)(int)))(int);
-Description
The signal function chooses one of three ways in which receipt of the signal number sig is to be subsequently handled. If the value of func is SIG_DFL, default handling @@ -12555,7 +12927,7 @@ unsigned long long int is executed for all other signals defined by the implementation.
The implementation shall behave as if no library function calls the signal function. -
Returns
If the request can be honored, the signal function returns the value of func for the most recent successful call to signal for the specified signal sig. Otherwise, a value of @@ -12563,30 +12935,33 @@ unsigned long long int
Forward references: the abort function (7.20.4.1), the exit function (7.20.4.3), the _Exit function (7.20.4.4). -
Footnotes
220) If any signal is generated by an asynchronous signal handler, the behavior is undefined. +
Synopsis
#include <signal.h>
int raise(int sig);
-Description
The raise function carries out the actions described in 7.14.1.1 for the signal sig. If a signal handler is called, the raise function shall not return until after the signal handler does. -
Returns
The raise function returns zero if successful, nonzero if unsuccessful. -
Contents +
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 @@ -12609,11 +12984,12 @@ unsigned long long int value of ap in the calling function is indeterminate and shall be passed to the va_end macro prior to any further reference to ap.221) -
Footnotes
221) It is permitted to create a pointer to a va_list and pass that pointer to another function, in which case the original function may make further use of the original list after the other function returns. +
The va_start and va_arg macros described in this subclause shall be implemented @@ -12624,14 +13000,15 @@ unsigned long long int shall be matched by a corresponding invocation of the va_end macro in the same function. +
Synopsis
#include <stdarg.h>
type va_arg(va_list ap, type);
-Description
The va_arg macro expands to an expression that has the specified type and the value of the next argument in the call. The parameter ap shall have been initialized by the @@ -12650,38 +13027,40 @@ unsigned long long int type, and the value is representable in both types;
Returns
The first invocation of the va_arg macro after that of the va_start macro returns the value of the argument after that specified by parmN . Successive invocations return the values of the remaining arguments in succession. +
Synopsis
#include <stdarg.h>
void va_copy(va_list dest, va_list src);
-Description
The va_copy macro initializes dest as a copy of src, as if the va_start macro had been applied to dest followed by the same sequence of uses of the va_arg macro as had previously been used to reach the present state of src. Neither the va_copy nor va_start macro shall be invoked to reinitialize dest without an intervening invocation of the va_end macro for the same dest. -
Returns
The va_copy macro returns no value. +
Synopsis
#include <stdarg.h>
void va_end(va_list ap);
-Description
The va_end macro facilitates a normal return from the function whose variable argument list was referred to by the expansion of the va_start macro, or the function @@ -12691,18 +13070,19 @@ unsigned long long int by the va_start or va_copy macro). If there is no corresponding invocation of the va_start or va_copy macro, or if the va_end macro is not invoked before the return, the behavior is undefined. -
Returns
The va_end macro returns no value. +
Synopsis
#include <stdarg.h>
void va_start(va_list ap, parmN);
-Description
The va_start macro shall be invoked before any access to the unnamed arguments.
@@ -12715,7 +13095,7 @@ unsigned long long int parmN is declared with the register storage class, with a function or array type, or with a type that is not compatible with the type that results after application of the default argument promotions, the behavior is undefined. -
Returns
The va_start macro returns no value.
@@ -12778,7 +13158,8 @@ unsigned long long int } -
Contents +
The header <stdbool.h> defines four macros.
@@ -12811,11 +13192,12 @@ unsigned long long int -
Footnotes
222) See ''future library directions'' (7.26.7). -
Contents +
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. @@ -12856,7 +13238,7 @@ unsigned long long int 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 @@ -12864,7 +13246,8 @@ unsigned long long int
Forward references: localization (7.11). -
Contents +
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 @@ -12890,12 +13273,13 @@ unsigned long long int shall provide those types described as ''required'', but need not provide any of the others (described as ''optional''). -
Footnotes
223) See ''future library directions'' (7.26.8).
224) Some of these types may denote implementation-defined extended integer types. +
When typedef names differing only in the absence or presence of the initial u are defined, @@ -12910,6 +13294,7 @@ unsigned long long int +
The typedef name intN_t designates a signed integer type with width N , no padding @@ -12923,6 +13308,7 @@ unsigned long long int 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. +
The typedef name int_leastN_t designates a signed integer type with a width of at @@ -12943,6 +13329,7 @@ unsigned long long int All other types of this form are optional. +
Each of the following types designates an integer type that is usually fastest225) to operate @@ -12966,12 +13353,13 @@ unsigned long long int All other types of this form are optional. -
Footnotes
225) The designated type is not guaranteed to be fastest for all purposes; if the implementation has no clear grounds for choosing one type over another, it will simply pick some integer type satisfying the signedness and width requirements. +
The following type designates a signed integer type with the property that any valid @@ -12988,6 +13376,7 @@ unsigned long long int These types are optional. +
The following type designates a signed integer type capable of representing any value of @@ -13002,6 +13391,7 @@ unsigned long long int These types are required. +
The following object-like macros226) specify the minimum and maximum limits of the @@ -13017,11 +13407,12 @@ unsigned long long int magnitude (absolute value) than the corresponding value given below, with the same sign, except where stated to be exactly the given value. -
Footnotes
226) C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined before <stdint.h> is included. +
The following object-like macros227) specify the minimum and maximum limits of @@ -13165,7 +13561,7 @@ unsigned long long int otherwise, wint_t is defined as an unsigned integer type, and the value of WINT_MIN shall be 0 and the value of WINT_MAX shall be no less than 65535. -
Footnotes
227) C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined before <stdint.h> is included. @@ -13175,6 +13571,7 @@ unsigned long long int character set. +
The following function-like macros230) expand to integer constants suitable for @@ -13195,11 +13592,12 @@ unsigned long long int -
Footnotes
230) C++ implementations should define these macros only when __STDC_CONSTANT_MACROS is defined before <stdint.h> is included. +
The macro INTN_C(value) shall expand to an integer constant expression @@ -13208,6 +13606,7 @@ unsigned long long int 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. +
The following macro expands to an integer constant expression having the value specified @@ -13222,8 +13621,10 @@ unsigned long long int UINTMAX_C(value) -
Contents +
The header <stdio.h> declares three types, several macros, and many functions for @@ -13328,13 +13729,14 @@ unsigned long long int
Forward references: files (7.19.3), the fseek function (7.19.9.2), streams (7.19.2), the tmpnam function (7.19.4.4), <wchar.h> (7.24). -
Footnotes
231) If the implementation imposes no practical limit on the length of file name strings, the value of FILENAME_MAX should instead be the recommended size of an array intended to hold a file name string. Of course, file name string contents are subject to other system-specific constraints; therefore all possible strings of length FILENAME_MAX cannot be expected to be opened successfully. +
Input and output, whether to or from physical devices such as terminals and tape drives, @@ -13391,7 +13793,7 @@ unsigned long long int 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 @@ -13405,7 +13807,7 @@ unsigned long long int -
Footnotes
232) An implementation need not distinguish between text streams and binary streams. In such an implementation, there need be no new-line characters in a text stream nor any limit to the length of a line. @@ -13413,6 +13815,7 @@ unsigned long long int
233) The three predefined streams stdin, stdout, and stderr are unoriented at program startup. +
A stream is associated with an external file (which may be a physical device) by opening @@ -13507,7 +13910,7 @@ unsigned long long int multibyte character. The wide character input/output functions and the byte input/output functions store the value of the macro EILSEQ in errno if and only if an encoding error occurs. -
Environmental limits
The value of FOPEN_MAX shall be at least eight, including the three standard text streams. @@ -13517,88 +13920,93 @@ unsigned long long int fputwc function (7.24.3.3), conversion state (7.24.6), the mbrtowc function (7.24.6.3.2), the wcrtomb function (7.24.6.3.3). -
Footnotes
234) Setting the file position indicator to end-of-file, as with fseek(file, 0, SEEK_END), has undefined behavior for a binary stream (because of possible trailing null characters) or for any stream with state-dependent encoding that does not assuredly end in the initial shift state. +
Synopsis
#include <stdio.h>
int remove(const char *filename);
-Description
The remove function causes the file whose name is the string pointed to by filename to be no longer accessible by that name. A subsequent attempt to open that file using that name will fail, unless it is created anew. If the file is open, the behavior of the remove function is implementation-defined. -
Returns
The remove function returns zero if the operation succeeds, nonzero if it fails. +
Synopsis
#include <stdio.h>
int rename(const char *old, const char *new);
-Description
The rename function causes the file whose name is the string pointed to by old to be henceforth known by the name given by the string pointed to by new. The file named old is no longer accessible by that name. If a file named by the string pointed to by new exists prior to the call to the rename function, the behavior is implementation-defined. -
Returns
The rename function returns zero if the operation succeeds, nonzero if it fails,235) in which case if the file existed previously it is still known by its original name. -
Footnotes
235) Among the reasons the implementation may cause the rename function to fail are that the file is open or that it is necessary to copy its contents to effectuate its renaming. +
Synopsis
#include <stdio.h>
FILE *tmpfile(void);
-Description
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 number simultaneously open other than this limit and any limit on the number of open files (FOPEN_MAX). -
Returns
The tmpfile function returns a pointer to the stream of the file that it created. If the file cannot be created, the tmpfile function returns a null pointer.
Forward references: the fopen function (7.19.5.3). +
Synopsis
#include <stdio.h>
char *tmpnam(char *s);
-Description
The tmpnam function generates a string that is a valid file name and that is not the same as the name of an existing file.236) The function is potentially capable of generating @@ -13611,7 +14019,7 @@ unsigned long long int The tmpnam function generates a different string each time it is called.
The implementation shall behave as if no library function calls the tmpnam function. -
Returns
If no suitable string can be generated, the tmpnam function returns a null pointer. Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an @@ -13619,27 +14027,29 @@ unsigned long long int 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. -
Footnotes
236) Files created using strings generated by the tmpnam function are temporary only in the sense that their names should not collide with those generated by conventional naming rules for the implementation. It is still necessary to use the remove function to remove such files when their use is ended, and before program termination. +
Synopsis
#include <stdio.h>
int fclose(FILE *stream);
-Description
A successful call to the fclose function causes the stream pointed to by stream to be flushed and the associated file to be closed. Any unwritten buffered data for the stream @@ -13647,20 +14057,21 @@ unsigned long long int are discarded. Whether or not the call succeeds, the stream is disassociated from the file and any buffer set by the setbuf or setvbuf function is disassociated from the stream (and deallocated if it was automatically allocated). -
Returns
The fclose function returns zero if the stream was successfully closed, or EOF if any errors were detected. +
Synopsis
#include <stdio.h>
int fflush(FILE *stream);
-Description
If stream points to an output stream or an update stream in which the most recent operation was not input, the fflush function causes any unwritten data for that stream @@ -13669,21 +14080,22 @@ unsigned long long int
If stream is a null pointer, the fflush function performs this flushing action on all streams for which the behavior is defined above. -
Returns
The fflush function sets the error indicator for the stream and returns EOF if a write error occurs, otherwise it returns zero.
Forward references: the fopen function (7.19.5.3). +
Synopsis
#include <stdio.h>
FILE *fopen(const char * restrict filename,
const char * restrict mode);
-Description
The fopen function opens the file whose name is the string pointed to by filename, and associates a stream with it. @@ -13728,20 +14140,21 @@ unsigned long long int
When opened, a stream is fully buffered if and only if it can be determined not to refer to an interactive device. The error and end-of-file indicators for the stream are cleared. -
Returns
The fopen function returns a pointer to the object controlling the stream. If the open operation fails, fopen returns a null pointer.
Forward references: file positioning functions (7.19.9). -
Footnotes
237) If the string begins with one of the above sequences, the implementation might choose to ignore the remaining characters, or it might use them to select different kinds of a file (some of which might not conform to the properties in 7.19.2). +
Synopsis
#include <stdio.h>
@@ -13749,7 +14162,7 @@ unsigned long long int
const char * restrict mode,
FILE * restrict stream);
-Description
The freopen function opens the file whose name is the string pointed to by filename and associates the stream pointed to by stream with it. The mode argument is used just @@ -13764,37 +14177,39 @@ unsigned long long int The freopen function first attempts to close any file that is associated with the specified stream. Failure to close the file is ignored. The error and end-of-file indicators for the stream are cleared. -
Returns
The freopen function returns a null pointer if the open operation fails. Otherwise, freopen returns the value of stream. -
Footnotes
238) The primary use of the freopen function is to change the file associated with a standard text stream (stderr, stdin, or stdout), as those identifiers need not be modifiable lvalues to which the value returned by the fopen function may be assigned. +
Synopsis
#include <stdio.h>
void setbuf(FILE * restrict stream,
char * restrict buf);
-Description
Except that it returns no value, the setbuf function is equivalent to the setvbuf function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf is a null pointer), with the value _IONBF for mode. -
Returns
The setbuf function returns no value.
Forward references: the setvbuf function (7.19.5.6). +
Synopsis
#include <stdio.h>
@@ -13807,7 +14222,7 @@ unsigned long long int
-Description
+Description
The setvbuf function may be used only after the stream pointed to by stream has
been associated with an open file and before any other operation (other than an
@@ -13819,34 +14234,36 @@ unsigned long long int
specifies the size of the array; otherwise, size may determine the size of a buffer
allocated by the setvbuf function. The contents of the array at any time are
indeterminate.
-
Returns
+Returns
The setvbuf function returns zero on success, or nonzero if an invalid value is given
for mode or if the request cannot be honored.
-
footnotes
+Footnotes
239) The buffer has to have a lifetime at least as great as the open stream, so the stream should be closed
before a buffer that has automatic storage duration is deallocated upon block exit.
+
7.19.6 Formatted input/output functions
The formatted input/output functions shall behave as if there is a sequence point after the
actions associated with each specifier.240)
-
footnotes
+Footnotes
240) The fprintf functions perform writes to memory for the %n specifier.
+
7.19.6.1 The fprintf function
-Synopsis
+Synopsis
#include <stdio.h>
int fprintf(FILE * restrict stream,
const char * restrict format, ...);
-Description
+Description
The fprintf function writes output to the stream pointed to by stream, under control
of the string pointed to by format that specifies how subsequent arguments are
@@ -14093,7 +14510,7 @@ If a length modifier appears with any conversion specifier other than as specifi
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
+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
@@ -14108,11 +14525,11 @@ If a length modifier appears with any conversion specifier other than as specifi
adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value
of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
the error should have a correct sign for the current rounding direction.
-
Returns
+Returns
The fprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
-
Environmental limits
+Environmental limits
The number of characters that can be produced by any single conversion shall be at least
4095.
@@ -14167,7 +14584,7 @@ If a length modifier appears with any conversion specifier other than as specifi
Forward references: conversion state (7.24.6), the wcrtomb function (7.24.6.3.3).
-
footnotes
+Footnotes
241) Note that 0 is taken as a flag, not as the beginning of a field width.
242) The results of all floating conversions of a negative zero, and of negative values that round to zero,
@@ -14195,15 +14612,16 @@ If a length modifier appears with any conversion specifier other than as specifi
the case of fixed-point conversion by the source value as well.
+
7.19.6.2 The fscanf function
-Synopsis
+Synopsis
#include <stdio.h>
int fscanf(FILE * restrict stream,
const char * restrict format, ...);
-Description
+Description
The fscanf function reads input from the stream pointed to by stream, under control
of the string pointed to by format that specifies the admissible input sequences and how
@@ -14401,7 +14819,7 @@ If a length modifier appears with any conversion specifier other than as specifi
Trailing white space (including new-line characters) is left unread unless matched by a
directive. The success of literal matches and suppressed assignments is not directly
determinable other than via the %n directive.
-
Returns
+Returns
The fscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the function returns the number of input items
@@ -14547,7 +14965,7 @@ If a length modifier appears with any conversion specifier other than as specifi
(7.24.6), the wcrtomb function (7.24.6.3.3).
-
footnotes
+Footnotes
250) These white-space characters are not counted against a specified field width.
251) fscanf pushes back at most one input character onto the input stream. Therefore, some sequences
@@ -14560,49 +14978,52 @@ If a length modifier appears with any conversion specifier other than as specifi
253) See ''future library directions'' (7.26.9).
+
7.19.6.3 The printf function
-Synopsis
+Synopsis
#include <stdio.h>
int printf(const char * restrict format, ...);
-Description
+Description
The printf function is equivalent to fprintf with the argument stdout interposed
before the arguments to printf.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
int scanf(const char * restrict format, ...);
-Description
+Description
The scanf function is equivalent to fscanf with the argument stdin interposed
before the arguments to scanf.
-
Returns
+Returns
The scanf function returns the value of the macro EOF if an input failure occurs before
any conversion. Otherwise, the scanf function returns the number of input items
assigned, which can be fewer than provided for, or even zero, in the event of an early
matching failure.
+
7.19.6.5 The snprintf function
-Synopsis
+Synopsis
#include <stdio.h>
int snprintf(char * restrict s, size_t n,
const char * restrict format, ...);
-Description
+Description
The snprintf function is equivalent to fprintf, except that the output is written into
an array (specified by argument s) rather than to a stream. If n is zero, nothing is written,
@@ -14611,47 +15032,49 @@ If a length modifier appears with any conversion specifier other than as specifi
of the characters actually written into the array. If copying takes place between objects
that overlap, the behavior is undefined.
-
Returns
+Returns
The snprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
value if an encoding error occurred. Thus, the null-terminated output has been
completely written if and only if the returned value is nonnegative and less than n.
+
7.19.6.6 The sprintf function
-Synopsis
+Synopsis
#include <stdio.h>
int sprintf(char * restrict s,
const char * restrict format, ...);
-Description
+Description
The sprintf function is equivalent to fprintf, except that the output is written into
an array (specified by the argument s) rather than to a stream. A null character is written
at the end of the characters written; it is not counted as part of the returned value. If
copying takes place between objects that overlap, the behavior is undefined.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
int sscanf(const char * restrict s,
const char * restrict format, ...);
-Description
+Description
The sscanf function is equivalent to fscanf, except that input is obtained from a
string (specified by the argument s) rather than from a stream. Reaching the end of the
string is equivalent to encountering end-of-file for the fscanf function. If copying
takes place between objects that overlap, the behavior is undefined.
-
Returns
+Returns
The sscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the sscanf function returns the number of input
@@ -14659,8 +15082,9 @@ If a length modifier appears with any conversion specifier other than as specifi
early matching failure.
+
7.19.6.8 The vfprintf function
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14669,13 +15093,13 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict format,
va_list arg);
-Description
+Description
The vfprintf function is equivalent to fprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfprintf function does not invoke the
va_end macro.254)
-
Returns
+Returns
The vfprintf function returns the number of characters transmitted, or a negative
value if an output or encoding error occurred.
@@ -14701,13 +15125,14 @@ If a length modifier appears with any conversion specifier other than as specifi
-
footnotes
+Footnotes
254) As the functions vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf, and
vsscanf invoke the va_arg macro, the value of arg after the return is indeterminate.
+
7.19.6.9 The vfscanf function
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14716,21 +15141,22 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict format,
va_list arg);
-Description
+Description
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)
-
Returns
+Returns
The vfscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vfscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
+
7.19.6.10 The vprintf function
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14738,20 +15164,21 @@ If a length modifier appears with any conversion specifier other than as specifi
int vprintf(const char * restrict format,
va_list arg);
-Description
+Description
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)
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14759,21 +15186,22 @@ If a length modifier appears with any conversion specifier other than as specifi
int vscanf(const char * restrict format,
va_list arg);
-Description
+Description
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)
-
Returns
+Returns
The vscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
+
7.19.6.12 The vsnprintf function
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14782,14 +15210,14 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict format,
va_list arg);
-Description
+Description
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
undefined.
-
Returns
+Returns
The vsnprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
@@ -14797,8 +15225,9 @@ If a length modifier appears with any conversion specifier other than as specifi
completely written if and only if the returned value is nonnegative and less than n.
+
7.19.6.13 The vsprintf function
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14807,20 +15236,21 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict format,
va_list arg);
-Description
+Description
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
undefined.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdarg.h>
@@ -14829,13 +15259,13 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict format,
va_list arg);
-Description
+Description
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)
-
Returns
+Returns
The vsscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vsscanf function returns the number of input
@@ -14843,22 +15273,24 @@ If a length modifier appears with any conversion specifier other than as specifi
early matching failure.
+
7.19.7 Character input/output functions
+7.19.7.1 The fgetc function
-Synopsis
+Synopsis
#include <stdio.h>
int fgetc(FILE *stream);
-Description
+Description
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next character is present, the fgetc function obtains that character as an unsigned
char converted to an int and advances the associated file position indicator for the
stream (if defined).
-
Returns
+Returns
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
@@ -14866,25 +15298,26 @@ If a length modifier appears with any conversion specifier other than as specifi
If a read error occurs, the error indicator for the stream is set and the fgetc function
returns EOF.255)
-
footnotes
+Footnotes
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
-Synopsis
+Synopsis
#include <stdio.h>
char *fgets(char * restrict s, int n,
FILE * restrict stream);
-Description
+Description
The fgets function reads at most one less than the number of characters specified by n
from the stream pointed to by stream into the array pointed to by s. No additional
characters are read after a new-line character (which is retained) or after end-of-file. A
null character is written immediately after the last character read into the array.
-
Returns
+Returns
The fgets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
@@ -14896,93 +15329,98 @@ If a length modifier appears with any conversion specifier other than as specifi
+
7.19.7.3 The fputc function
-Synopsis
+Synopsis
#include <stdio.h>
int fputc(int c, FILE *stream);
-Description
+Description
The fputc function writes the character specified by c (converted to an unsigned
char) to the output stream pointed to by stream, at the position indicated by the
associated file position indicator for the stream (if defined), and advances the indicator
appropriately. If the file cannot support positioning requests, or if the stream was opened
with append mode, the character is appended to the output stream.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
int fputs(const char * restrict s,
FILE * restrict stream);
-Description
+Description
The fputs function writes the string pointed to by s to the stream pointed to by
stream. The terminating null character is not written.
-
Returns
+Returns
The fputs function returns EOF if a write error occurs; otherwise it returns a
nonnegative value.
+
7.19.7.5 The getc function
-Synopsis
+Synopsis
#include <stdio.h>
int getc(FILE *stream);
-Description
+Description
The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
may evaluate stream more than once, so the argument should never be an expression
with side effects.
-
Returns
+Returns
The getc function returns the next character from the input stream pointed to by
stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
getc returns EOF. If a read error occurs, the error indicator for the stream is set and
getc returns EOF.
+
7.19.7.6 The getchar function
-Synopsis
+Synopsis
#include <stdio.h>
int getchar(void);
-Description
+Description
The getchar function is equivalent to getc with the argument stdin.
-
Returns
+Returns
The getchar function returns the next character from the input stream pointed to by
stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
getchar returns EOF. If a read error occurs, the error indicator for the stream is set and
getchar returns EOF.
+
7.19.7.7 The gets function
-Synopsis
+Synopsis
#include <stdio.h>
char *gets(char *s);
-Description
+Description
The gets function reads characters from the input stream pointed to by stdin, into the
array pointed to by s, until end-of-file is encountered or a new-line character is read.
Any new-line character is discarded, and a null character is written immediately after the
last character read into the array.
-
Returns
+Returns
The gets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
@@ -14991,64 +15429,68 @@ If a length modifier appears with any conversion specifier other than as specifi
Forward references: future library directions (7.26.9).
+
7.19.7.8 The putc function
-Synopsis
+Synopsis
#include <stdio.h>
int putc(int c, FILE *stream);
-Description
+Description
The putc function is equivalent to fputc, except that if it is implemented as a macro, it
may evaluate stream more than once, so that argument should never be an expression
with side effects.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
int putchar(int c);
-Description
+Description
The putchar function is equivalent to putc with the second argument stdout.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
int puts(const char *s);
-Description
+Description
The puts function writes the string pointed to by s to the stream pointed to by stdout,
and appends a new-line character to the output. The terminating null character is not
written.
-
Returns
+Returns
The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative
value.
+
7.19.7.11 The ungetc function
-Synopsis
+Synopsis
#include <stdio.h>
int ungetc(int c, FILE *stream);
-Description
+Description
The ungetc function pushes the character specified by c (converted to an unsigned
char) back onto the input stream pointed to by stream. Pushed-back characters will be
@@ -15072,7 +15514,7 @@ If a length modifier appears with any conversion specifier other than as specifi
For a binary stream, its file position indicator is decremented by each successful call to
the ungetc function; if its value was zero before a call, it is indeterminate after the
call.256)
-
Returns
+Returns
The ungetc function returns the character pushed back after conversion, or EOF if the
operation fails.
@@ -15083,14 +15525,16 @@ If a length modifier appears with any conversion specifier other than as specifi
-
footnotes
+Footnotes
256) See ''future library directions'' (7.26.9).
+
7.19.8 Direct input/output functions
+7.19.8.1 The fread function
-Synopsis
+Synopsis
#include <stdio.h>
@@ -15098,7 +15542,7 @@ If a length modifier appears with any conversion specifier other than as specifi
size_t size, size_t nmemb,
FILE * restrict stream);
-Description
+Description
The fread function reads, into the array pointed to by ptr, up to nmemb elements
whose size is specified by size, from the stream pointed to by stream. For each
@@ -15107,15 +15551,16 @@ If a length modifier appears with any conversion specifier other than as specifi
indicator for the stream (if defined) is advanced by the number of characters successfully
read. If an error occurs, the resulting value of the file position indicator for the stream is
indeterminate. If a partial element is read, its value is indeterminate.
-
Returns
+Returns
The fread function returns the number of elements successfully read, which may be
less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero,
fread returns zero and the contents of the array and the state of the stream remain
unchanged.
+
7.19.8.2 The fwrite function
-Synopsis
+Synopsis
#include <stdio.h>
@@ -15123,7 +15568,7 @@ If a length modifier appears with any conversion specifier other than as specifi
size_t size, size_t nmemb,
FILE * restrict stream);
-Description
+Description
The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
whose size is specified by size, to the stream pointed to by stream. For each object,
@@ -15133,42 +15578,45 @@ If a length modifier appears with any conversion specifier other than as specifi
error occurs, the resulting value of the file position indicator for the stream is
indeterminate.
-
Returns
+Returns
The fwrite function returns the number of elements successfully written, which will be
less than nmemb only if a write error is encountered. If size or nmemb is zero,
fwrite returns zero and the state of the stream remains unchanged.
+
7.19.9 File positioning functions
+7.19.9.1 The fgetpos function
-Synopsis
+Synopsis
#include <stdio.h>
int fgetpos(FILE * restrict stream,
fpos_t * restrict pos);
-Description
+Description
The fgetpos function stores the current values of the parse state (if any) and file
position indicator for the stream pointed to by stream in the object pointed to by pos.
The values stored contain unspecified information usable by the fsetpos function for
repositioning the stream to its position at the time of the call to the fgetpos function.
-
Returns
+Returns
If successful, the fgetpos function returns zero; on failure, the fgetpos function
returns nonzero and stores an implementation-defined positive value in errno.
Forward references: the fsetpos function (7.19.9.3).
+
7.19.9.2 The fseek function
-Synopsis
+Synopsis
#include <stdio.h>
int fseek(FILE *stream, long int offset, int whence);
-Description
+Description
The fseek function sets the file position indicator for the stream pointed to by stream.
If a read or write error occurs, the error indicator for the stream is set and fseek fails.
@@ -15188,19 +15636,20 @@ If a length modifier appears with any conversion specifier other than as specifi
effects of the ungetc function on the stream, clears the end-of-file indicator for the
stream, and then establishes the new position. After a successful fseek call, the next
operation on an update stream may be either input or output.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
int fsetpos(FILE *stream, const fpos_t *pos);
-Description
+Description
The fsetpos function sets the mbstate_t object (if any) and file position indicator
for the stream pointed to by stream according to the value of the object pointed to by
@@ -15212,19 +15661,20 @@ If a length modifier appears with any conversion specifier other than as specifi
on the stream, clears the end-of-file indicator for the stream, and then establishes the new
parse state and position. After a successful fsetpos call, the next operation on an
update stream may be either input or output.
-
Returns
+Returns
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
-Synopsis
+Synopsis
#include <stdio.h>
long int ftell(FILE *stream);
-Description
+Description
The ftell function obtains the current value of the file position indicator for the stream
pointed to by stream. For a binary stream, the value is the number of characters from
@@ -15234,20 +15684,21 @@ If a length modifier appears with any conversion specifier other than as specifi
return values is not necessarily a meaningful measure of the number of characters written
or read.
-
Returns
+Returns
If successful, the ftell function returns the current value of the file position indicator
for the stream. On failure, the ftell function returns -1L and stores an
implementation-defined positive value in errno.
+
7.19.9.5 The rewind function
-Synopsis
+Synopsis
#include <stdio.h>
void rewind(FILE *stream);
-Description
+Description
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
@@ -15255,66 +15706,71 @@ If a length modifier appears with any conversion specifier other than as specifi
(void)fseek(stream, 0L, SEEK_SET)
except that the error indicator for the stream is also cleared.
-Returns
The rewind function returns no value. +
Synopsis
#include <stdio.h>
void clearerr(FILE *stream);
-Description
The clearerr function clears the end-of-file and error indicators for the stream pointed to by stream. -
Returns
The clearerr function returns no value. +
Synopsis
#include <stdio.h>
int feof(FILE *stream);
-Description
The feof function tests the end-of-file indicator for the stream pointed to by stream. -
Returns
The feof function returns nonzero if and only if the end-of-file indicator is set for stream. +
Synopsis
#include <stdio.h>
int ferror(FILE *stream);
-Description
The ferror function tests the error indicator for the stream pointed to by stream. -
Returns
The ferror function returns nonzero if and only if the error indicator is set for stream. +
Synopsis
#include <stdio.h>
void perror(const char *s);
-Description
The perror function maps the error number in the integer expression errno to an error message. It writes a sequence of characters to the standard error stream thus: first @@ -15322,13 +15778,14 @@ If a length modifier appears with any conversion specifier other than as specifi string pointed to by s followed by a colon (:) and a space; then an appropriate error message string followed by a new-line character. The contents of the error message strings are the same as those returned by the strerror function with argument errno. -
Returns
The perror function returns no value.
Forward references: the strerror function (7.21.6.2). -
Contents +
The header <stdlib.h> declares five types and several functions of general utility, and defines several macros.257) @@ -15375,37 +15832,40 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
257) See ''future library directions'' (7.26.10). +
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. +
Synopsis
#include <stdlib.h>
double atof(const char *nptr);
-Description
The atof function converts the initial portion of the string pointed to by nptr to double representation. Except for the behavior on error, it is equivalent to
strtod(nptr, (char **)NULL)
-Returns
The atof function returns the converted value.
Forward references: the strtod, strtof, and strtold functions (7.20.1.3). +
Synopsis
#include <stdlib.h>
@@ -15413,7 +15873,7 @@ If a length modifier appears with any conversion specifier other than as specifi
long int atol(const char *nptr);
long long int atoll(const char *nptr);
-Description
The atoi, atol, and atoll functions convert the initial portion of the string pointed to by nptr to int, long int, and long long int representation, respectively. @@ -15423,15 +15883,16 @@ If a length modifier appears with any conversion specifier other than as specifi atol: strtol(nptr, (char **)NULL, 10) atoll: strtoll(nptr, (char **)NULL, 10) -
Returns
The atoi, atol, and atoll functions return the converted value.
Forward references: the strtol, strtoll, strtoul, and strtoull functions (7.20.1.4). +
Synopsis
#include <stdlib.h>
@@ -15442,7 +15903,7 @@ If a length modifier appears with any conversion specifier other than as specifi
long double strtold(const char * restrict nptr,
char ** restrict endptr);
-Description
The strtod, strtof, and strtold functions convert the initial portion of the string pointed to by nptr to double, float, and long double representation, @@ -15500,7 +15961,7 @@ If a length modifier appears with any conversion specifier other than as specifi 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 @@ -15519,7 +15980,7 @@ If a length modifier appears with any conversion specifier other than as specifi stipulation that the error with respect to D should have a correct sign for the current rounding direction.260) -
Returns
The functions return the converted value, if any. If no conversion could be performed, zero is returned. If the correct value is outside the range of representable values, plus or @@ -15529,7 +15990,7 @@ If a length modifier appears with any conversion specifier other than as specifi than the smallest normalized positive number in the return type; whether errno acquires the value ERANGE is implementation-defined. -
Footnotes
258) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by negating the value resulting from converting the corresponding unsigned sequence (see F.5); the two methods may yield different results if rounding is toward positive or negative infinity. In either case, @@ -15542,8 +16003,9 @@ If a length modifier appears with any conversion specifier other than as specifi to the same internal floating value, but if not will round to adjacent values. +
Synopsis
#include <stdlib.h>
@@ -15564,7 +16026,7 @@ If a length modifier appears with any conversion specifier other than as specifi
char ** restrict endptr,
int base);
-Description
The strtol, strtoll, strtoul, and strtoull functions convert the initial portion of the string pointed to by nptr to long int, long long int, unsigned @@ -15609,7 +16071,7 @@ If a length modifier appears with any conversion specifier other than as specifi If the subject sequence is empty or does not have the expected form, no conversion is performed; the value of nptr is stored in the object pointed to by endptr, provided that endptr is not a null pointer. -
Returns
The strtol, strtoll, strtoul, and strtoull functions return the converted value, if any. If no conversion could be performed, zero is returned. If the correct value @@ -15618,36 +16080,39 @@ If a length modifier appears with any conversion specifier other than as specifi and sign of the value, if any), and the value of the macro ERANGE is stored in errno. +
Synopsis
#include <stdlib.h>
int rand(void);
-Description
The rand function computes a sequence of pseudo-random integers in the range 0 to RAND_MAX.
The implementation shall behave as if no library function calls the rand function. -
Returns
The rand function returns a pseudo-random integer. -
Environmental limits
The value of the RAND_MAX macro shall be at least 32767. +
Synopsis
#include <stdlib.h>
void srand(unsigned int seed);
-Description
The srand function uses the argument as a seed for a new sequence of pseudo-random numbers to be returned by subsequent calls to rand. If srand is then called with the @@ -15656,7 +16121,7 @@ If a length modifier appears with any conversion specifier other than as specifi as when srand is first called with a seed value of 1.
The implementation shall behave as if no library function calls the srand function. -
Returns
The srand function returns no value.
@@ -15676,6 +16141,7 @@ If a length modifier appears with any conversion specifier other than as specifi +
The order and contiguity of storage allocated by successive calls to the calloc, @@ -15690,34 +16156,36 @@ If a length modifier appears with any conversion specifier other than as specifi 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. +
Synopsis
#include <stdlib.h>
void *calloc(size_t nmemb, size_t size);
-Description
The calloc function allocates space for an array of nmemb objects, each of whose size is size. The space is initialized to all bits zero.261) -
Returns
The calloc function returns either a null pointer or a pointer to the allocated space. -
Footnotes
261) Note that this need not be the same as the representation of floating-point zero or a null pointer constant. +
Synopsis
#include <stdlib.h>
void free(void *ptr);
-Description
The free function causes the space pointed to by ptr to be deallocated, that is, made available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if @@ -15727,33 +16195,35 @@ If a length modifier appears with any conversion specifier other than as specifi realloc function, or if the space has been deallocated by a call to free or realloc, the behavior is undefined. -
Returns
The free function returns no value. +
Synopsis
#include <stdlib.h>
void *malloc(size_t size);
-Description
The malloc function allocates space for an object whose size is specified by size and whose value is indeterminate. -
Returns
The malloc function returns either a null pointer or a pointer to the allocated space. +
Synopsis
#include <stdlib.h>
void *realloc(void *ptr, size_t size);
-Description
The realloc function deallocates the old object pointed to by ptr and returns a pointer to a new object that has the size specified by size. The contents of the new @@ -15766,23 +16236,25 @@ If a length modifier appears with any conversion specifier other than as specifi calloc, malloc, or realloc function, or if the space has been deallocated by a call to the free or realloc function, the behavior is undefined. If memory for the new object cannot be allocated, the old object is not deallocated and its value is unchanged. -
Returns
The realloc function returns a pointer to the new object (which may have the same value as a pointer to the old object), or a null pointer if the new object could not be allocated. +
Synopsis
#include <stdlib.h>
void abort(void);
-Description
The abort function causes abnormal program termination to occur, unless the signal SIGABRT is being caught and the signal handler does not return. Whether open streams @@ -15790,37 +16262,39 @@ If a length modifier appears with any conversion specifier other than as specifi removed is implementation-defined. An implementation-defined form of the status unsuccessful termination is returned to the host environment by means of the function call raise(SIGABRT). -
Returns
The abort function does not return to its caller. +
Synopsis
#include <stdlib.h>
int atexit(void (*func)(void));
-Description
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. -
Returns
The atexit function returns zero if the registration succeeds, nonzero if it fails.
Forward references: the exit function (7.20.4.3). +
Synopsis
#include <stdlib.h>
void exit(int status);
-Description
The exit function causes normal program termination to occur. If more than one call to the exit function is executed by a program, the behavior is undefined. @@ -15840,23 +16314,24 @@ If a length modifier appears with any conversion specifier other than as specifi returned. If the value of status is EXIT_FAILURE, an implementation-defined form of the status unsuccessful termination is returned. Otherwise the status returned is implementation-defined. -
Returns
The exit function cannot return to its caller. -
Footnotes
262) Each function is called as many times as it was registered, and in the correct order with respect to other registered functions. +
Synopsis
#include <stdlib.h>
void _Exit(int status);
-Description
The _Exit function causes normal program termination to occur and control to be returned to the host environment. No functions registered by the atexit function or @@ -15864,7 +16339,7 @@ If a length modifier appears with any conversion specifier other than as specifi host environment is determined in the same way as for the exit function (7.20.4.3). Whether open streams with unwritten buffered data are flushed, open streams are closed, or temporary files are removed is implementation-defined. -
Returns
The _Exit function cannot return to its caller. @@ -15873,48 +16348,51 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <stdlib.h>
char *getenv(const char *name);
-Description
The getenv function searches an environment list, provided by the host environment, for a string that matches the string pointed to by name. The set of environment names and the method for altering the environment list are implementation-defined.
The implementation shall behave as if no library function calls the getenv function. -
Returns
The getenv function returns a pointer to a string associated with the matched list member. The string pointed to shall not be modified by the program, but may be overwritten by a subsequent call to the getenv function. If the specified name cannot be found, a null pointer is returned. +
Synopsis
#include <stdlib.h>
int system(const char *string);
-Description
If string is a null pointer, the system function determines whether the host environment has a command processor. If string is not a null pointer, the system function passes the string pointed to by string to that command processor to be executed in a manner which the implementation shall document; this might then cause the program calling system to behave in a non-conforming manner or to terminate. -
Returns
If the argument is a null pointer, the system function returns nonzero only if a command processor is available. If the argument is not a null pointer, and the system function does return, it returns an implementation-defined value. +
These utilities make use of a comparison function to search or sort arrays of unspecified @@ -15943,7 +16421,7 @@ If a length modifier appears with any conversion specifier other than as specifi comparison function, and also between any call to the comparison function and any movement of the objects passed as arguments to that call. -
Footnotes
263) That is, if the value passed is p, then the following expressions are always nonzero:
@@ -15953,8 +16431,9 @@ If a length modifier appears with any conversion specifier other than as specifi
+
Synopsis
#include <stdlib.h>
@@ -15962,7 +16441,7 @@ If a length modifier appears with any conversion specifier other than as specifi
size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
-Description
The bsearch function searches an array of nmemb objects, the initial element of which is pointed to by base, for an element that matches the object pointed to by key. The @@ -15977,25 +16456,26 @@ If a length modifier appears with any conversion specifier other than as specifi respectively, to be less than, to match, or to be greater than the array element. The array shall consist of: all the elements that compare less than, all the elements that compare equal to, and all the elements that compare greater than the key object, in that order.264) -
Returns
The bsearch function returns a pointer to a matching element of the array, or a null pointer if no match is found. If two elements compare as equal, which element is matched is unspecified. -
Footnotes
264) In practice, the entire array is sorted according to the comparison function. +
Synopsis
#include <stdlib.h>
void qsort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
-Description
The qsort function sorts an array of nmemb objects, the initial element of which is pointed to by base. The size of each object is specified by size. @@ -16007,7 +16487,7 @@ If a length modifier appears with any conversion specifier other than as specifi or greater than the second.
If two elements compare as equal, their order in the resulting sorted array is unspecified. -
Returns
The qsort function returns no value. @@ -16016,10 +16496,12 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <stdlib.h>
@@ -16027,20 +16509,21 @@ If a length modifier appears with any conversion specifier other than as specifi
long int labs(long int j);
long long int llabs(long long int j);
-Description
The abs, labs, and llabs functions compute the absolute value of an integer j. If the result cannot be represented, the behavior is undefined.265) -
Returns
The abs, labs, and llabs, functions return the absolute value. -
Footnotes
265) The absolute value of the most negative number cannot be represented in two's complement. +
Synopsis
#include <stdlib.h>
@@ -16048,11 +16531,11 @@ If a length modifier appears with any conversion specifier other than as specifi
ldiv_t ldiv(long int numer, long int denom);
lldiv_t lldiv(long long int numer, long long int denom);
-Description
The div, ldiv, and lldiv, functions compute numer / denom and numer % denom in a single operation. -
Returns
The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and lldiv_t, respectively, comprising both the quotient and the remainder. The structures @@ -16065,6 +16548,7 @@ If a length modifier appears with any conversion specifier other than as specifi +
The behavior of the multibyte character functions is affected by the LC_CTYPE category @@ -16076,19 +16560,20 @@ If a length modifier appears with any conversion specifier other than as specifi otherwise.266) Changing the LC_CTYPE category causes the conversion state of these functions to be indeterminate. -
Footnotes
266) If the locale employs special bytes to change the shift state, these bytes do not produce separate wide character codes, but are grouped with an adjacent multibyte character. +
Synopsis
#include <stdlib.h>
int mblen(const char *s, size_t n);
-Description
If s is not a null pointer, the mblen function determines the number of bytes contained in the multibyte character pointed to by s. Except that the conversion state of the @@ -16098,7 +16583,7 @@ If a length modifier appears with any conversion specifier other than as specifi
The implementation shall behave as if no library function calls the mblen function. -
Returns
If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte character encodings, respectively, do or do not have state-dependent encodings. If s is @@ -16113,8 +16598,9 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <stdlib.h>
@@ -16122,7 +16608,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict s,
size_t n);
-Description
If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with the byte pointed to by s to determine the number of bytes needed to complete the next @@ -16133,7 +16619,7 @@ If a length modifier appears with any conversion specifier other than as specifi character, the function is left in the initial conversion state.
The implementation shall behave as if no library function calls the mbtowc function. -
Returns
If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte character encodings, respectively, do or do not have state-dependent encodings. If s is @@ -16145,14 +16631,15 @@ If a length modifier appears with any conversion specifier other than as specifi In no case will the value returned be greater than n or the value of the MB_CUR_MAX macro. +
Synopsis
#include <stdlib.h>
int wctomb(char *s, wchar_t wc);
-Description
The wctomb function determines the number of bytes needed to represent the multibyte character corresponding to the wide character given by wc (including any shift @@ -16164,7 +16651,7 @@ If a length modifier appears with any conversion specifier other than as specifi
The implementation shall behave as if no library function calls the wctomb function. -
Returns
If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte character encodings, respectively, do or do not have state-dependent encodings. If s is @@ -16174,13 +16661,15 @@ If a length modifier appears with any conversion specifier other than as specifi
In no case will the value returned be greater than the value of the MB_CUR_MAX macro. +
The behavior of the multibyte string functions is affected by the LC_CTYPE category of the current locale. +
Synopsis
#include <stdlib.h>
@@ -16188,7 +16677,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict s,
size_t n);
-Description
The mbstowcs function converts a sequence of multibyte characters that begins in the initial shift state from the array pointed to by s into a sequence of corresponding wide @@ -16200,7 +16689,7 @@ If a length modifier appears with any conversion specifier other than as specifi
No more than n elements will be modified in the array pointed to by pwcs. If copying takes place between objects that overlap, the behavior is undefined. -
Returns
If an invalid multibyte character is encountered, the mbstowcs function returns (size_t)(-1). Otherwise, the mbstowcs function returns the number of array @@ -16211,12 +16700,13 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
267) The array will not be null-terminated if the value returned is n. +
Synopsis
#include <stdlib.h>
@@ -16224,7 +16714,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict pwcs,
size_t n);
-Description
The wcstombs function converts a sequence of wide characters from the array pointed to by pwcs into a sequence of corresponding multibyte characters that begins in the @@ -16235,7 +16725,7 @@ If a length modifier appears with any conversion specifier other than as specifi
No more than n bytes will be modified in the array pointed to by s. If copying takes place between objects that overlap, the behavior is undefined. -
Returns
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 @@ -16243,8 +16733,10 @@ If a length modifier appears with any conversion specifier other than as specifi any.267) -
Contents +
The header <string.h> declares one type and several functions, and defines one @@ -16266,14 +16758,16 @@ If a length modifier appears with any conversion specifier other than as specifi unsigned char (and therefore every possible object representation is valid and has a different value). -
Footnotes
268) See ''future library directions'' (7.26.11). +
Synopsis
#include <string.h>
@@ -16281,12 +16775,12 @@ If a length modifier appears with any conversion specifier other than as specifi
const void * restrict s2,
size_t n);
-Description
The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. If copying takes place between objects that overlap, the behavior is undefined. -
Returns
The memcpy function returns the value of s1. @@ -16295,43 +16789,46 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <string.h>
void *memmove(void *s1, const void *s2, size_t n);
-Description
The memmove function copies n characters from the object pointed to by s2 into the object pointed to by s1. Copying takes place as if the n characters from the object pointed to by s2 are first copied into a temporary array of n characters that does not overlap the objects pointed to by s1 and s2, and then the n characters from the temporary array are copied into the object pointed to by s1. -
Returns
The memmove function returns the value of s1. +
Synopsis
#include <string.h>
char *strcpy(char * restrict s1,
const char * restrict s2);
-Description
The strcpy function copies the string pointed to by s2 (including the terminating null character) into the array pointed to by s1. If copying takes place between objects that overlap, the behavior is undefined. -
Returns
The strcpy function returns the value of s1. +
Synopsis
#include <string.h>
@@ -16339,7 +16836,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict s2,
size_t n);
-Description
The strncpy function copies not more than n characters (characters that follow a null character are not copied) from the array pointed to by s2 to the array pointed to by @@ -16349,37 +16846,40 @@ If a length modifier appears with any conversion specifier other than as specifi If the array pointed to by s2 is a string that is shorter than n characters, null characters are appended to the copy in the array pointed to by s1, until n characters in all have been written. -
Returns
The strncpy function returns the value of s1. -
Footnotes
269) Thus, if there is no null character in the first n characters of the array pointed to by s2, the result will not be null-terminated. +
Synopsis
#include <string.h>
char *strcat(char * restrict s1,
const char * restrict s2);
-Description
The strcat function appends a copy of the string pointed to by s2 (including the terminating null character) to the end of the string pointed to by s1. The initial character of s2 overwrites the null character at the end of s1. If copying takes place between objects that overlap, the behavior is undefined. -
Returns
The strcat function returns the value of s1. +
Synopsis
#include <string.h>
@@ -16387,7 +16887,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict s2,
size_t n);
-Description
The strncat function appends not more than n characters (a null character and characters that follow it are not appended) from the array pointed to by s2 to the end of @@ -16396,16 +16896,17 @@ If a length modifier appears with any conversion specifier other than as specifi takes place between objects that overlap, the behavior is undefined. -
Returns
The strncat function returns the value of s1.
Forward references: the strlen function (7.21.6.3). -
Footnotes
270) Thus, the maximum number of characters that can end up in the array pointed to by s1 is strlen(s1)+n+1. +
The sign of a nonzero value returned by the comparison functions memcmp, strcmp, @@ -16413,41 +16914,43 @@ If a length modifier appears with any conversion specifier other than as specifi pair of characters (both interpreted as unsigned char) that differ in the objects being compared. +
Synopsis
#include <string.h>
int memcmp(const void *s1, const void *s2, size_t n);
-Description
The memcmp function compares the first n characters of the object pointed to by s1 to the first n characters of the object pointed to by s2.271) -
Returns
The memcmp function returns an integer greater than, equal to, or less than zero, accordingly as the object pointed to by s1 is greater than, equal to, or less than the object pointed to by s2. -
Footnotes
271) The contents of ''holes'' used as padding for purposes of alignment within structure objects are indeterminate. Strings shorter than their allocated space and unions may also cause problems in comparison. +
Synopsis
#include <string.h>
int strcmp(const char *s1, const char *s2);
-Description
The strcmp function compares the string pointed to by s1 to the string pointed to by s2. -
Returns
The strcmp function returns an integer greater than, equal to, or less than zero, accordingly as the string pointed to by s1 is greater than, equal to, or less than the string @@ -16455,43 +16958,46 @@ If a length modifier appears with any conversion specifier other than as specifi pointed to by s2. +
Synopsis
#include <string.h>
int strcoll(const char *s1, const char *s2);
-Description
The strcoll function compares the string pointed to by s1 to the string pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the current locale. -
Returns
The strcoll function returns an integer greater than, equal to, or less than zero, accordingly as the string pointed to by s1 is greater than, equal to, or less than the string pointed to by s2 when both are interpreted as appropriate to the current locale. +
Synopsis
#include <string.h>
int strncmp(const char *s1, const char *s2, size_t n);
-Description
The strncmp function compares not more than n characters (characters that follow a null character are not compared) from the array pointed to by s1 to the array pointed to by s2. -
Returns
The strncmp function returns an integer greater than, equal to, or less than zero, accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal to, or less than the possibly null-terminated array pointed to by s2. +
Synopsis
#include <string.h>
@@ -16499,7 +17005,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict s2,
size_t n);
-Description
The strxfrm function transforms the string pointed to by s2 and places the resulting string into the array pointed to by s1. The transformation is such that if the strcmp @@ -16510,7 +17016,7 @@ If a length modifier appears with any conversion specifier other than as specifi pointed to by s1, including the terminating null character. If n is zero, s1 is permitted to be a null pointer. If copying takes place between objects that overlap, the behavior is undefined. -
Returns
The strxfrm function returns the length of the transformed string (not including the terminating null character). If the value returned is n or more, the contents of the array @@ -16523,134 +17029,143 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <string.h>
void *memchr(const void *s, int c, size_t n);
-Description
The memchr function locates the first occurrence of c (converted to an unsigned char) in the initial n characters (each interpreted as unsigned char) of the object pointed to by s. -
Returns
The memchr function returns a pointer to the located character, or a null pointer if the character does not occur in the object. +
Synopsis
#include <string.h>
char *strchr(const char *s, int c);
-Description
The strchr function locates the first occurrence of c (converted to a char) in the string pointed to by s. The terminating null character is considered to be part of the string. -
Returns
The strchr function returns a pointer to the located character, or a null pointer if the character does not occur in the string. +
Synopsis
#include <string.h>
size_t strcspn(const char *s1, const char *s2);
-Description
The strcspn function computes the length of the maximum initial segment of the string pointed to by s1 which consists entirely of characters not from the string pointed to by s2. -
Returns
The strcspn function returns the length of the segment. +
Synopsis
#include <string.h>
char *strpbrk(const char *s1, const char *s2);
-Description
The strpbrk function locates the first occurrence in the string pointed to by s1 of any character from the string pointed to by s2. -
Returns
The strpbrk function returns a pointer to the character, or a null pointer if no character from s2 occurs in s1. +
Synopsis
#include <string.h>
char *strrchr(const char *s, int c);
-Description
The strrchr function locates the last occurrence of c (converted to a char) in the string pointed to by s. The terminating null character is considered to be part of the string. -
Returns
The strrchr function returns a pointer to the character, or a null pointer if c does not occur in the string. +
Synopsis
#include <string.h>
size_t strspn(const char *s1, const char *s2);
-Description
The strspn function computes the length of the maximum initial segment of the string pointed to by s1 which consists entirely of characters from the string pointed to by s2. -
Returns
The strspn function returns the length of the segment. +
Synopsis
#include <string.h>
char *strstr(const char *s1, const char *s2);
-Description
The strstr function locates the first occurrence in the string pointed to by s1 of the sequence of characters (excluding the terminating null character) in the string pointed to by s2. -
Returns
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. +
Synopsis
#include <string.h>
char *strtok(char * restrict s1,
const char * restrict s2);
-Description
A sequence of calls to the strtok function breaks the string pointed to by s1 into a sequence of tokens, each of which is delimited by a character from the string pointed to @@ -16675,7 +17190,7 @@ If a length modifier appears with any conversion specifier other than as specifi searching from the saved pointer and behaves as described above.
The implementation shall behave as if no library function calls the strtok function. -
Returns
The strtok function returns a pointer to the first character of a token, or a null pointer if there is no token. @@ -16692,61 +17207,66 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <string.h>
void *memset(void *s, int c, size_t n);
-Description
The memset function copies the value of c (converted to an unsigned char) into each of the first n characters of the object pointed to by s. -
Returns
The memset function returns the value of s. +
Synopsis
#include <string.h>
char *strerror(int errnum);
-Description
The strerror function maps the number in errnum to a message string. Typically, the values for errnum come from errno, but strerror shall map any value of type int to a message.
The implementation shall behave as if no library function calls the strerror function. -
Returns
The strerror function returns a pointer to the string, the contents of which are locale- specific. The array pointed to shall not be modified by the program, but may be overwritten by a subsequent call to the strerror function. +
Synopsis
#include <string.h>
size_t strlen(const char *s);
-Description
The strlen function computes the length of the string pointed to by s. -
Returns
The strlen function returns the number of characters that precede the terminating null character. -
Contents +
The header <tgmath.h> includes the headers <math.h> and <complex.h> and defines several type-generic macros. @@ -16870,7 +17390,7 @@ If a length modifier appears with any conversion specifier other than as specifi cproj(ldc) cprojl(ldc) -
Footnotes
272) Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to make available the corresponding ordinary function. @@ -16878,8 +17398,10 @@ If a length modifier appears with any conversion specifier other than as specifi the behavior is undefined. -
Contents +
The header <time.h> defines two macros, and declares several types and functions for @@ -16932,23 +17454,25 @@ If a length modifier appears with any conversion specifier other than as specifi The value of tm_isdst is positive if Daylight Saving Time is in effect, zero if Daylight Saving Time is not in effect, and negative if the information is not available. -
Footnotes
274) The range [0, 60] for tm_sec allows for a positive leap second. +
Synopsis
#include <time.h>
clock_t clock(void);
-Description
The clock function determines the processor time used. -
Returns
The clock function returns the implementation's best approximation to the processor time used by the program since the beginning of an implementation-defined era related @@ -16957,23 +17481,24 @@ If a length modifier appears with any conversion specifier other than as specifi the processor time used is not available or its value cannot be represented, the function returns the value (clock_t)(-1).275) -
Footnotes
275) In order to measure the time spent in a program, the clock function should be called at the start of the program and its return value subtracted from the value returned by subsequent calls. +
Synopsis
#include <time.h>
double difftime(time_t time1, time_t time0);
-Description
The difftime function computes the difference between two calendar times: time1 - time0. -
Returns
The difftime function returns the difference expressed in seconds as a double. @@ -16982,14 +17507,15 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <time.h>
time_t mktime(struct tm *timeptr);
-Description
The mktime function converts the broken-down time, expressed as local time, in the structure pointed to by timeptr into a calendar time value with the same encoding as @@ -17000,7 +17526,7 @@ If a length modifier appears with any conversion specifier other than as specifi set appropriately, and the other components are set to represent the specified calendar time, but with their values forced to the ranges indicated above; the final value of tm_mday is not set until tm_mon and tm_year are determined. -
Returns
The mktime function returns the specified calendar time encoded as a value of type time_t. If the calendar time cannot be represented, the function returns the value @@ -17036,30 +17562,32 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
276) Thus, a positive or zero value for tm_isdst causes the mktime function to presume initially that Daylight Saving Time, respectively, is or is not in effect for the specified time. A negative value causes it to attempt to determine whether Daylight Saving Time is in effect for the specified time. +
Synopsis
#include <time.h>
time_t time(time_t *timer);
-Description
The time function determines the current calendar time. The encoding of the value is unspecified. -
Returns
The time function returns the implementation's best approximation to the current calendar time. The value (time_t)(-1) is returned if the calendar time is not available. If timer is not a null pointer, the return value is also assigned to the object it points to. +
Except for the strftime function, these functions each return a pointer to one of two @@ -17069,14 +17597,15 @@ If a length modifier appears with any conversion specifier other than as specifi previous call to any of them. The implementation shall behave as if no other library functions call these functions. +
Synopsis
#include <time.h>
char *asctime(const struct tm *timeptr);
-Description
The asctime function converts the broken-down time in the structure pointed to by timeptr into a string in the form @@ -17105,65 +17634,69 @@ If a length modifier appears with any conversion specifier other than as specifi return result; } -
Returns
The asctime function returns a pointer to the string. +
Synopsis
#include <time.h>
char *ctime(const time_t *timer);
-Description
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))
-Returns
The ctime function returns the pointer returned by the asctime function with that broken-down time as argument.
Forward references: the localtime function (7.23.3.4). +
Synopsis
#include <time.h>
struct tm *gmtime(const time_t *timer);
-Description
The gmtime function converts the calendar time pointed to by timer into a broken- down time, expressed as UTC. -
Returns
The gmtime function returns a pointer to the broken-down time, or a null pointer if the specified time cannot be converted to UTC. +
Synopsis
#include <time.h>
struct tm *localtime(const time_t *timer);
-Description
The localtime function converts the calendar time pointed to by timer into a broken-down time, expressed as local time. -
Returns
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. +
Synopsis
#include <time.h>
@@ -17172,7 +17705,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const char * restrict format,
const struct tm * restrict timeptr);
-Description
The strftime function places characters into the array pointed to by s as controlled by the string pointed to by format. The format shall be a multibyte character sequence, @@ -17313,7 +17846,7 @@ If a length modifier appears with any conversion specifier other than as specifi
Returns
If the total number of resulting characters including the terminating null character is not more than maxsize, the strftime function returns the number of characters placed @@ -17321,8 +17854,10 @@ If a length modifier appears with any conversion specifier other than as specifi zero is returned and the contents of the array are indeterminate. -
Contents +
The header <wchar.h> declares four data types, one tag, four macros, and many @@ -17376,7 +17911,7 @@ If a length modifier appears with any conversion specifier other than as specifi subclause causes copying to take place between objects that overlap, the behavior is undefined. -
Footnotes
277) See ''future library directions'' (7.26.12).
278) wchar_t and wint_t can be the same integer type. @@ -17384,17 +17919,19 @@ If a length modifier appears with any conversion specifier other than as specifi
279) The value of the macro WEOF may differ from that of EOF and need not be negative. +
The formatted wide character input/output functions shall behave as if there is a sequence point after the actions associated with each specifier.280) -
Footnotes
280) The fwprintf functions perform writes to memory for the %n specifier. +
Synopsis
#include <stdio.h>
@@ -17402,7 +17939,7 @@ If a length modifier appears with any conversion specifier other than as specifi
int fwprintf(FILE * restrict stream,
const wchar_t * restrict format, ...);
-Description
The fwprintf function writes output to the stream pointed to by stream, under control of the wide string pointed to by format that specifies how subsequent arguments @@ -17640,7 +18177,7 @@ If a length modifier appears with any conversion specifier other than as specifi
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 @@ -17655,13 +18192,13 @@ If a length modifier appears with any conversion specifier other than as specifi adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that the error should have a correct sign for the current rounding direction. -
Returns
The fwprintf function returns the number of wide characters transmitted, or a negative 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. @@ -17683,7 +18220,7 @@ If a length modifier appears with any conversion specifier other than as specifi
Forward references: the btowc function (7.24.6.1.1), the mbrtowc function (7.24.6.3.2). -
Footnotes
281) Note that 0 is taken as a flag, not as the beginning of a field width.
282) The results of all floating conversions of a negative zero, and of negative values that round to zero, @@ -17707,8 +18244,9 @@ If a length modifier appears with any conversion specifier other than as specifi the case of fixed-point conversion by the source value as well. +
Synopsis
#include <stdio.h>
@@ -17716,7 +18254,7 @@ If a length modifier appears with any conversion specifier other than as specifi
int fwscanf(FILE * restrict stream,
const wchar_t * restrict format, ...);
-Description
The fwscanf function reads input from the stream pointed to by stream, under control of the wide string pointed to by format that specifies the admissible input @@ -17914,7 +18452,7 @@ If a length modifier appears with any conversion specifier other than as specifi Trailing white space (including new-line wide characters) is left unread unless matched by a directive. The success of literal matches and suppressed assignments is not directly determinable other than via the %n directive. -
Returns
The fwscanf function returns the value of the macro EOF if an input failure occurs before any conversion. Otherwise, the function returns the number of input items @@ -17958,7 +18496,7 @@ If a length modifier appears with any conversion specifier other than as specifi wcstol, wcstoll, wcstoul, and wcstoull functions (7.24.4.1.2), the wcrtomb function (7.24.6.3.3). -
Footnotes
288) These white-space wide characters are not counted against a specified field width.
289) fwscanf pushes back at most one input wide character onto the input stream. Therefore, some @@ -17967,8 +18505,9 @@ If a length modifier appears with any conversion specifier other than as specifi
290) See ''future library directions'' (7.26.12). +
Synopsis
#include <wchar.h>
@@ -17976,33 +18515,34 @@ If a length modifier appears with any conversion specifier other than as specifi
size_t n,
const wchar_t * restrict format, ...);
-Description
The swprintf function is equivalent to fwprintf, except that the argument s specifies an array of wide characters into which the generated output is to be written, rather than written to a stream. No more than n wide characters are written, including a terminating null wide character, which is always added (unless n is zero). -
Returns
The swprintf function returns the number of wide characters written in the array, not counting the terminating null wide character, or a negative value if an encoding error occurred or if n or more wide characters were requested to be written. +
Synopsis
#include <wchar.h>
int swscanf(const wchar_t * restrict s,
const wchar_t * restrict format, ...);
-Description
The swscanf function is equivalent to fwscanf, except that the argument s specifies a wide string from which the input is to be obtained, rather than from a stream. Reaching the end of the wide string is equivalent to encountering end-of-file for the fwscanf function. -
Returns
The swscanf function returns the value of the macro EOF if an input failure occurs before any conversion. Otherwise, the swscanf function returns the number of input @@ -18010,8 +18550,9 @@ If a length modifier appears with any conversion specifier other than as specifi early matching failure. +
Synopsis
#include <stdarg.h>
@@ -18021,13 +18562,13 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict format,
va_list arg);
-Description
The vfwprintf function is equivalent to fwprintf, with the variable argument list replaced by arg, which shall have been initialized by the va_start macro (and possibly subsequent va_arg calls). The vfwprintf function does not invoke the va_end macro.291) -
Returns
The vfwprintf function returns the number of wide characters transmitted, or a negative value if an output or encoding error occurred. @@ -18055,13 +18596,14 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
291) As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf invoke the va_arg macro, the value of arg after the return is indeterminate. +
Synopsis
#include <stdarg.h>
@@ -18071,21 +18613,22 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict format,
va_list arg);
-Description
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) -
Returns
The vfwscanf function returns the value of the macro EOF if an input failure occurs before any conversion. Otherwise, the vfwscanf function returns the number of input items assigned, which can be fewer than provided for, or even zero, in the event of an early matching failure. +
Synopsis
#include <stdarg.h>
@@ -18095,21 +18638,22 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict format,
va_list arg);
-Description
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) -
Returns
The vswprintf function returns the number of wide characters written in the array, not counting the terminating null wide character, or a negative value if an encoding error occurred or if n or more wide characters were requested to be generated. +
Synopsis
#include <stdarg.h>
@@ -18118,21 +18662,22 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict format,
va_list arg);
-Description
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) -
Returns
The vswscanf function returns the value of the macro EOF if an input failure occurs before any conversion. Otherwise, the vswscanf function returns the number of input items assigned, which can be fewer than provided for, or even zero, in the event of an early matching failure. +
Synopsis
#include <stdarg.h>
@@ -18140,20 +18685,21 @@ If a length modifier appears with any conversion specifier other than as specifi
int vwprintf(const wchar_t * restrict format,
va_list arg);
-Description
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) -
Returns
The vwprintf function returns the number of wide characters transmitted, or a negative value if an output or encoding error occurred. +
Synopsis
#include <stdarg.h>
@@ -18161,71 +18707,75 @@ If a length modifier appears with any conversion specifier other than as specifi
int vwscanf(const wchar_t * restrict format,
va_list arg);
-Description
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) -
Returns
The vwscanf function returns the value of the macro EOF if an input failure occurs before any conversion. Otherwise, the vwscanf function returns the number of input items assigned, which can be fewer than provided for, or even zero, in the event of an early matching failure. +
Synopsis
#include <wchar.h>
int wprintf(const wchar_t * restrict format, ...);
-Description
The wprintf function is equivalent to fwprintf with the argument stdout interposed before the arguments to wprintf. -
Returns
The wprintf function returns the number of wide characters transmitted, or a negative value if an output or encoding error occurred. +
Synopsis
#include <wchar.h>
int wscanf(const wchar_t * restrict format, ...);
-Description
The wscanf function is equivalent to fwscanf with the argument stdin interposed before the arguments to wscanf. -
Returns
The wscanf function returns the value of the macro EOF if an input failure occurs before any conversion. Otherwise, the wscanf function returns the number of input items assigned, which can be fewer than provided for, or even zero, in the event of an early matching failure. +
Synopsis
#include <stdio.h>
#include <wchar.h>
wint_t fgetwc(FILE *stream);
-Description
If the end-of-file indicator for the input stream pointed to by stream is not set and a next wide character is present, the fgetwc function obtains that wide character as a wchar_t converted to a wint_t and advances the associated file position indicator for the stream (if defined). -
Returns
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end- of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise, @@ -18234,13 +18784,14 @@ If a length modifier appears with any conversion specifier other than as specifi function returns WEOF. If an encoding error occurs (including too few bytes), the value of the macro EILSEQ is stored in errno and the fgetwc function returns WEOF.292) -
Footnotes
292) An end-of-file and a read error can be distinguished by use of the feof and ferror functions. Also, errno will be set to EILSEQ by input/output functions only if an encoding error occurs. +
Synopsis
#include <stdio.h>
@@ -18248,7 +18799,7 @@ If a length modifier appears with any conversion specifier other than as specifi
wchar_t *fgetws(wchar_t * restrict s,
int n, FILE * restrict stream);
-Description
The fgetws function reads at most one less than the number of wide characters specified by n from the stream pointed to by stream into the array pointed to by s. No @@ -18258,36 +18809,38 @@ If a length modifier appears with any conversion specifier other than as specifi additional wide characters are read after a new-line wide character (which is retained) or after end-of-file. A null wide character is written immediately after the last wide character read into the array. -
Returns
The fgetws function returns s if successful. If end-of-file is encountered and no characters have been read into the array, the contents of the array remain unchanged and a null pointer is returned. If a read or encoding error occurs during the operation, the array contents are indeterminate and a null pointer is returned. +
Synopsis
#include <stdio.h>
#include <wchar.h>
wint_t fputwc(wchar_t c, FILE *stream);
-Description
The fputwc function writes the wide character specified by c to the output stream pointed to by stream, at the position indicated by the associated file position indicator for the stream (if defined), and advances the indicator appropriately. If the file cannot support positioning requests, or if the stream was opened with append mode, the character is appended to the output stream. -
Returns
The fputwc function returns the wide character written. If a write error occurs, the error indicator for the stream is set and fputwc returns WEOF. If an encoding error occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF. +
Synopsis
#include <stdio.h>
@@ -18295,60 +18848,63 @@ If a length modifier appears with any conversion specifier other than as specifi
int fputws(const wchar_t * restrict s,
FILE * restrict stream);
-Description
The fputws function writes the wide string pointed to by s to the stream pointed to by stream. The terminating null wide character is not written. -
Returns
The fputws function returns EOF if a write or encoding error occurs; otherwise, it returns a nonnegative value. +
Synopsis
#include <stdio.h>
#include <wchar.h>
int fwide(FILE *stream, int mode);
-Description
The fwide function determines the orientation of the stream pointed to by stream. If mode is greater than zero, the function first attempts to make the stream wide oriented. If mode is less than zero, the function first attempts to make the stream byte oriented.293) Otherwise, mode is zero and the function does not alter the orientation of the stream. -
Returns
The fwide function returns a value greater than zero if, after the call, the stream has wide orientation, a value less than zero if the stream has byte orientation, or zero if the stream has no orientation. -
Footnotes
293) If the orientation of the stream has already been determined, fwide does not change it. +
Synopsis
#include <stdio.h>
#include <wchar.h>
wint_t getwc(FILE *stream);
-Description
The getwc function is equivalent to fgetwc, except that if it is implemented as a macro, it may evaluate stream more than once, so the argument should never be an expression with side effects. -
Returns
The getwc function returns the next wide character from the input stream pointed to by stream, or WEOF. +
Synopsis
#include <wchar.h>
@@ -18359,54 +18915,57 @@ If a length modifier appears with any conversion specifier other than as specifi
-Description
+Description
The getwchar function is equivalent to getwc with the argument stdin.
-
Returns
+Returns
The getwchar function returns the next wide character from the input stream pointed to
by stdin, or WEOF.
+
7.24.3.8 The putwc function
-Synopsis
+Synopsis
#include <stdio.h>
#include <wchar.h>
wint_t putwc(wchar_t c, FILE *stream);
-Description
+Description
The putwc function is equivalent to fputwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so that argument should never be an
expression with side effects.
-
Returns
+Returns
The putwc function returns the wide character written, or WEOF.
+
7.24.3.9 The putwchar function
-Synopsis
+Synopsis
#include <wchar.h>
wint_t putwchar(wchar_t c);
-Description
+Description
The putwchar function is equivalent to putwc with the second argument stdout.
-
Returns
+Returns
The putwchar function returns the character written, or WEOF.
+
7.24.3.10 The ungetwc function
-Synopsis
+Synopsis
#include <stdio.h>
#include <wchar.h>
wint_t ungetwc(wint_t c, FILE *stream);
-Description
+Description
The ungetwc function pushes the wide character specified by c back onto the input
stream pointed to by stream. Pushed-back wide characters will be returned by
@@ -18431,11 +18990,12 @@ If a length modifier appears with any conversion specifier other than as specifi
back. For a text or binary stream, the value of its file position indicator after a successful
call to the ungetwc function is unspecified until all pushed-back wide characters are
read or discarded.
-
Returns
+Returns
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
@@ -18452,10 +19012,12 @@ If a length modifier appears with any conversion specifier other than as specifi
zero wide characters.
+
7.24.4.1 Wide string numeric conversion functions
+7.24.4.1.1 The wcstod, wcstof, and wcstold functions
-Synopsis
+Synopsis
#include <wchar.h>
@@ -18466,7 +19028,7 @@ If a length modifier appears with any conversion specifier other than as specifi
long double wcstold(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);
-Description
+Description
The wcstod, wcstof, and wcstold functions convert the initial portion of the wide
string pointed to by nptr to double, float, and long double representation,
@@ -18529,7 +19091,7 @@ If a length modifier appears with any conversion specifier other than as specifi
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
+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
@@ -18550,7 +19112,7 @@ If a length modifier appears with any conversion specifier other than as specifi
correctly rounding L and U according to the current rounding direction, with the extra
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.296)
-
Returns
+Returns
The functions return the converted value, if any. If no conversion could be performed,
zero is returned. If the correct value is outside the range of representable values, plus or
@@ -18565,7 +19127,7 @@ If a length modifier appears with any conversion specifier other than as specifi
-
footnotes
+Footnotes
294) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
negating the value resulting from converting the corresponding unsigned sequence (see F.5); the two
methods may yield different results if rounding is toward positive or negative infinity. In either case,
@@ -18578,8 +19140,9 @@ If a length modifier appears with any conversion specifier other than as specifi
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
-Synopsis
+Synopsis
#include <wchar.h>
@@ -18600,7 +19163,7 @@ If a length modifier appears with any conversion specifier other than as specifi
wchar_t ** restrict endptr,
int base);
-Description
+Description
The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
portion of the wide string pointed to by nptr to long int, long long int,
@@ -18645,7 +19208,7 @@ If a length modifier appears with any conversion specifier other than as specifi
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
-
Returns
+Returns
The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
@@ -18653,27 +19216,30 @@ If a length modifier appears with any conversion specifier other than as specifi
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
+7.24.4.2.1 The wcscpy function
-Synopsis
+Synopsis
#include <wchar.h>
wchar_t *wcscpy(wchar_t * restrict s1,
const wchar_t * restrict s2);
-Description
+Description
The wcscpy function copies the wide string pointed to by s2 (including the terminating
null wide character) into the array pointed to by s1.
-
Returns
+Returns
The wcscpy function returns the value of s1.
+
7.24.4.2.2 The wcsncpy function
-Synopsis
+Synopsis
#include <wchar.h>
@@ -18681,7 +19247,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict s2,
size_t n);
-Description
+Description
The wcsncpy function copies not more than n wide characters (those that follow a null
wide character are not copied) from the array pointed to by s2 to the array pointed to by
@@ -18690,17 +19256,18 @@ If a length modifier appears with any conversion specifier other than as specifi
If the array pointed to by s2 is a wide string that is shorter than n wide characters, null
wide characters are appended to the copy in the array pointed to by s1, until n wide
characters in all have been written.
-
Returns
+Returns
The wcsncpy function returns the value of s1.
-
footnotes
+Footnotes
297) Thus, if there is no null wide character in the first n wide characters of the array pointed to by s2, the
result will not be null-terminated.
+
7.24.4.2.3 The wmemcpy function
-Synopsis
+Synopsis
#include <wchar.h>
@@ -18708,11 +19275,11 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict s2,
size_t n);
-Description
+Description
The wmemcpy function copies n wide characters from the object pointed to by s2 to the
object pointed to by s1.
-
Returns
+Returns
The wmemcpy function returns the value of s1.
@@ -18721,46 +19288,50 @@ If a length modifier appears with any conversion specifier other than as specifi
+
7.24.4.2.4 The wmemmove function
-Synopsis
+Synopsis
#include <wchar.h>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
size_t n);
-Description
+Description
The wmemmove function copies n wide characters from the object pointed to by s2 to
the object pointed to by s1. Copying takes place as if the n wide characters from the
object pointed to by s2 are first copied into a temporary array of n wide characters that
does not overlap the objects pointed to by s1 or s2, and then the n wide characters from
the temporary array are copied into the object pointed to by s1.
-
Returns
+Returns
The wmemmove function returns the value of s1.
+
7.24.4.3 Wide string concatenation functions
+7.24.4.3.1 The wcscat function
-Synopsis
+Synopsis
#include <wchar.h>
wchar_t *wcscat(wchar_t * restrict s1,
const wchar_t * restrict s2);
-Description
+Description
The wcscat function appends a copy of the wide string pointed to by s2 (including the
terminating null wide character) to the end of the wide string pointed to by s1. The initial
wide character of s2 overwrites the null wide character at the end of s1.
-
Returns
+Returns
The wcscat function returns the value of s1.
+
7.24.4.3.2 The wcsncat function
-Synopsis
+Synopsis
#include <wchar.h>
@@ -18768,7 +19339,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict s2,
size_t n);
-Description
+Description
The wcsncat function appends not more than n wide characters (a null wide character
and those that follow it are not appended) from the array pointed to by s2 to the end of
@@ -18776,51 +19347,54 @@ If a length modifier appears with any conversion specifier other than as specifi
the wide string pointed to by s1. The initial wide character of s2 overwrites the null
wide character at the end of s1. A terminating null wide character is always appended to
the result.298)
-
Returns
+Returns
The wcsncat function returns the value of s1.
-
footnotes
+Footnotes
298) Thus, the maximum number of wide characters that can end up in the array pointed to by s1 is
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
-Synopsis
+Synopsis
#include <wchar.h>
int wcscmp(const wchar_t *s1, const wchar_t *s2);
-Description
+Description
The wcscmp function compares the wide string pointed to by s1 to the wide string
pointed to by s2.
-
Returns
+Returns
The wcscmp function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
wide string pointed to by s2.
+
7.24.4.4.2 The wcscoll function
-Synopsis
+Synopsis
#include <wchar.h>
int wcscoll(const wchar_t *s1, const wchar_t *s2);
-Description
+Description
The wcscoll function compares the wide string pointed to by s1 to the wide string
pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the
current locale.
-
Returns
+Returns
The wcscoll function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
@@ -18830,27 +19404,29 @@ If a length modifier appears with any conversion specifier other than as specifi
wide string pointed to by s2 when both are interpreted as appropriate to the current
locale.
+
7.24.4.4.3 The wcsncmp function
-Synopsis
+Synopsis
#include <wchar.h>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
size_t n);
-Description
+Description
The wcsncmp function compares not more than n wide characters (those that follow a
null wide character are not compared) from the array pointed to by s1 to the array
pointed to by s2.
-
Returns
+Returns
The wcsncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
+
7.24.4.4.4 The wcsxfrm function
-Synopsis
+Synopsis
#include <wchar.h>
@@ -18858,7 +19434,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict s2,
size_t n);
-Description
+Description
The wcsxfrm function transforms the wide string pointed to by s2 and places the
resulting wide string into the array pointed to by s1. The transformation is such that if
@@ -18867,7 +19443,7 @@ If a length modifier appears with any conversion specifier other than as specifi
applied to the same two original wide strings. No more than n wide characters are placed
into the resulting array pointed to by s1, including the terminating null wide character. If
n is zero, s1 is permitted to be a null pointer.
-
Returns
+Returns
The wcsxfrm function returns the length of the transformed wide string (not including
the terminating null wide character). If the value returned is n or greater, the contents of
@@ -18881,128 +19457,137 @@ If a length modifier appears with any conversion specifier other than as specifi
+Synopsis
#include <wchar.h>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
size_t n);
-Description
The wmemcmp function compares the first n wide characters of the object pointed to by s1 to the first n wide characters of the object pointed to by s2. -
Returns
The wmemcmp function returns an integer greater than, equal to, or less than zero, accordingly as the object pointed to by s1 is greater than, equal to, or less than the object pointed to by s2. +
Synopsis
#include <wchar.h>
wchar_t *wcschr(const wchar_t *s, wchar_t c);
-Description
The wcschr function locates the first occurrence of c in the wide string pointed to by s. The terminating null wide character is considered to be part of the wide string. -
Returns
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. +
Synopsis
#include <wchar.h>
size_t wcscspn(const wchar_t *s1, const wchar_t *s2);
-Description
The wcscspn function computes the length of the maximum initial segment of the wide string pointed to by s1 which consists entirely of wide characters not from the wide string pointed to by s2. -
Returns
The wcscspn function returns the length of the segment. +
Synopsis
#include <wchar.h>
wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);
-Description
The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of any wide character from the wide string pointed to by s2. -
Returns
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. +
Synopsis
#include <wchar.h>
wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
-Description
The wcsrchr function locates the last occurrence of c in the wide string pointed to by s. The terminating null wide character is considered to be part of the wide string. -
Returns
The wcsrchr function returns a pointer to the wide character, or a null pointer if c does not occur in the wide string. +
Synopsis
#include <wchar.h>
size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
-Description
The wcsspn function computes the length of the maximum initial segment of the wide string pointed to by s1 which consists entirely of wide characters from the wide string pointed to by s2. -
Returns
The wcsspn function returns the length of the segment. +
Synopsis
#include <wchar.h>
wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);
-Description
The wcsstr function locates the first occurrence in the wide string pointed to by s1 of the sequence of wide characters (excluding the terminating null wide character) in the wide string pointed to by s2. -
Returns
The wcsstr function returns a pointer to the located wide string, or a null pointer if the wide string is not found. If s2 points to a wide string with zero length, the function returns s1. +
Synopsis
#include <wchar.h>
@@ -19010,7 +19595,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict s2,
wchar_t ** restrict ptr);
-Description
A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into a sequence of tokens, each of which is delimited by a wide character from the wide string @@ -19041,7 +19626,7 @@ If a length modifier appears with any conversion specifier other than as specifi by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer value for ptr, shall start searching just past the element overwritten by a null wide character (if any). -
Returns
The wcstok function returns a pointer to the first wide character of a token, or a null pointer if there is no token. @@ -19060,60 +19645,66 @@ If a length modifier appears with any conversion specifier other than as specifi +
Synopsis
#include <wchar.h>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
size_t n);
-Description
The wmemchr function locates the first occurrence of c in the initial n wide characters of the object pointed to by s. -
Returns
The wmemchr function returns a pointer to the located wide character, or a null pointer if the wide character does not occur in the object. +
Synopsis
#include <wchar.h>
size_t wcslen(const wchar_t *s);
-Description
The wcslen function computes the length of the wide string pointed to by s. -
Returns
The wcslen function returns the number of wide characters that precede the terminating null wide character. +
Synopsis
#include <wchar.h>
wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
-Description
The wmemset function copies the value of c into each of the first n wide characters of the object pointed to by s. -
Returns
The wmemset function returns the value of s. +
Synopsis
#include <time.h>
@@ -19123,7 +19714,7 @@ If a length modifier appears with any conversion specifier other than as specifi
const wchar_t * restrict format,
const struct tm * restrict timeptr);
-Description
The wcsftime function is equivalent to the strftime function, except that:
Returns
If the total number of resulting wide characters including the terminating null wide character is not more than maxsize, the wcsftime function returns the number of @@ -19143,6 +19734,7 @@ If a length modifier appears with any conversion specifier other than as specifi wide character. Otherwise, zero is returned and the contents of the array are indeterminate. +
The header <wchar.h> declares an extended set of functions useful for conversion @@ -19174,70 +19766,76 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
299) Thus, a particular mbstate_t object can be used, for example, with both the mbrtowc and mbsrtowcs functions as long as they are used to step sequentially through the same multibyte character string. +
Synopsis
#include <stdio.h>
#include <wchar.h>
wint_t btowc(int c);
-Description
The btowc function determines whether c constitutes a valid single-byte character in the initial shift state. -
Returns
The btowc function returns WEOF if c has the value EOF or if (unsigned char)c does not constitute a valid single-byte character in the initial shift state. Otherwise, it returns the wide character representation of that character. +
Synopsis
#include <stdio.h>
#include <wchar.h>
int wctob(wint_t c);
-Description
The wctob function determines whether c corresponds to a member of the extended character set whose multibyte character representation is a single byte when in the initial shift state. -
Returns
The wctob function returns EOF if c does not correspond to a multibyte character with length one in the initial shift state. Otherwise, it returns the single-byte representation of that character as an unsigned char converted to an int. +
Synopsis
#include <wchar.h>
int mbsinit(const mbstate_t *ps);
-Description
If ps is not a null pointer, the mbsinit function determines whether the pointed-to mbstate_t object describes an initial conversion state. -
Returns
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. +
These functions differ from the corresponding multibyte character functions of 7.20.7 @@ -19251,8 +19849,9 @@ If a length modifier appears with any conversion specifier other than as specifi Also unlike their corresponding functions, the return value does not represent whether the encoding is state-dependent. +
Synopsis
#include <wchar.h>
@@ -19260,7 +19859,7 @@ If a length modifier appears with any conversion specifier other than as specifi
size_t n,
mbstate_t * restrict ps);
-Description
The mbrlen function is equivalent to the call:
@@ -19268,15 +19867,16 @@ If a length modifier appears with any conversion specifier other than as specifiwhere internal is the mbstate_t object for the mbrlen function, except that the expression designated by ps is evaluated only once. -
Returns
The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2), or (size_t)(-1).
Forward references: the mbrtowc function (7.24.6.3.2). +
Synopsis
#include <wchar.h>
@@ -19285,7 +19885,7 @@ If a length modifier appears with any conversion specifier other than as specifi
size_t n,
mbstate_t * restrict ps);
-Description
If s is a null pointer, the mbrtowc function is equivalent to the call:
@@ -19300,7 +19900,7 @@ If a length modifier appears with any conversion specifier other than as specifi corresponding wide character and then, if pwc is not a null pointer, stores that value in the object pointed to by pwc. If the corresponding wide character is the null wide character, the resulting state described is the initial conversion state. -Returns
+Returns
The mbrtowc function returns the first of the following that applies (given the current conversion state): @@ -19320,13 +19920,14 @@ If a length modifier appears with any conversion specifier other than as specifi -
footnotes
+Footnotes
300) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a sequence of redundant shift sequences (for implementations with state-dependent encodings). +
7.24.6.3.3 The wcrtomb function
-Synopsis
+Synopsis
#include <wchar.h> @@ -19334,7 +19935,7 @@ If a length modifier appears with any conversion specifier other than as specifi wchar_t wc, mbstate_t * restrict ps);-Description
+Description
If s is a null pointer, the wcrtomb function is equivalent to the call
@@ -19348,13 +19949,14 @@ If a length modifier appears with any conversion specifier other than as specifi array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If wc is a null wide character, a null byte is stored, preceded by any shift sequence needed to restore the initial shift state; the resulting state described is the initial conversion state. --Returns
+Returns
The wcrtomb function returns the number of bytes stored in the array object (including any shift sequences). When wc is not a valid wide character, an encoding error occurs: the function stores the value of the macro EILSEQ in errno and returns (size_t)(-1); the conversion state is unspecified. +
7.24.6.4 Restartable multibyte/wide string conversion functions
These functions differ from the corresponding multibyte string functions of 7.20.8 @@ -19371,8 +19973,9 @@ If a length modifier appears with any conversion specifier other than as specifi to reflect the amount of the source processed by that invocation. +
7.24.6.4.1 The mbsrtowcs function
-Synopsis
+Synopsis
#include <wchar.h> @@ -19381,7 +19984,7 @@ If a length modifier appears with any conversion specifier other than as specifi size_t len, mbstate_t * restrict ps);-Description
+Description
The mbsrtowcs function converts a sequence of multibyte characters that begins in the conversion state described by the object pointed to by ps, from the array indirectly @@ -19398,7 +20001,7 @@ If a length modifier appears with any conversion specifier other than as specifi just past the last multibyte character converted (if any). If conversion stopped due to reaching a terminating null character and if dst is not a null pointer, the resulting state described is the initial conversion state. -
Returns
+Returns
If the input conversion encounters a sequence of bytes that do not form a valid multibyte character, an encoding error occurs: the mbsrtowcs function stores the value of the @@ -19411,12 +20014,13 @@ If a length modifier appears with any conversion specifier other than as specifi -
footnotes
+Footnotes
301) Thus, the value of len is ignored if dst is a null pointer. +
7.24.6.4.2 The wcsrtombs function
-Synopsis
+Synopsis
#include <wchar.h> @@ -19425,7 +20029,7 @@ If a length modifier appears with any conversion specifier other than as specifi size_t len, mbstate_t * restrict ps);-Description
+Description
The wcsrtombs function converts a sequence of wide characters from the array indirectly pointed to by src into a sequence of corresponding multibyte characters that @@ -19443,7 +20047,7 @@ If a length modifier appears with any conversion specifier other than as specifi address just past the last wide character converted (if any). If conversion stopped due to reaching a terminating null wide character, the resulting state described is the initial conversion state. -
Returns
+Returns
If conversion stops because a wide character is reached that does not correspond to a valid multibyte character, an encoding error occurs: the wcsrtombs function stores the @@ -19456,13 +20060,15 @@ If a length modifier appears with any conversion specifier other than as specifi -
footnotes
+Footnotes
302) If conversion stops because a terminating null wide character has been reached, the bytes stored include those necessary to reach the initial shift state immediately before the null byte. -
7.25 Wide character classification and mapping utilities
+Contents +
7.25 Wide character classification and mapping utilities <wctype.h>
+7.25.1 Introduction
The header <wctype.h> declares three data types, one macro, and many functions.303) @@ -19505,10 +20111,11 @@ If a length modifier appears with any conversion specifier other than as specifi -
footnotes
+Footnotes
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 @@ -19519,6 +20126,7 @@ If a length modifier appears with any conversion specifier other than as specifi 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 @@ -19531,33 +20139,35 @@ If a length modifier appears with any conversion specifier other than as specifi both printing and white-space wide characters.304)
Forward references: the wctob function (7.24.6.1.2). -
footnotes
+Footnotes
304) For example, if the expression isalpha(wctob(wc)) evaluates to true, then the call iswalpha(wc) also returns true. But, if the expression isgraph(wctob(wc)) evaluates to true (which cannot occur for wc == L' ' of course), then either iswgraph(wc) or iswprint(wc) && iswspace(wc) is true, but not both. +
7.25.2.1.1 The iswalnum function
-Synopsis
+Synopsis
#include <wctype.h> int iswalnum(wint_t wc);-Description
+Description
The iswalnum function tests for any wide character for which iswalpha or iswdigit is true. +
7.25.2.1.2 The iswalpha function
-Synopsis
+Synopsis
#include <wctype.h> int iswalpha(wint_t wc);-Description
+Description
The iswalpha function tests for any wide character for which iswupper or iswlower is true, or any wide character that is one of a locale-specific set of alphabetic @@ -19566,19 +20176,20 @@ If a length modifier appears with any conversion specifier other than as specifi wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace is true.305) -
footnotes
+Footnotes
305) The functions iswlower and iswupper test true or false separately for each of these additional wide characters; all four combinations are possible. +
7.25.2.1.3 The iswblank function
-Synopsis
+Synopsis
#include <wctype.h> int iswblank(wint_t wc);-Description
+Description
The iswblank function tests for any wide character that is a standard blank wide character or is one of a locale-specific set of wide characters for which iswspace is true @@ -19586,31 +20197,34 @@ If a length modifier appears with any conversion specifier other than as specifi 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
-Synopsis
+Synopsis
#include <wctype.h> int iswcntrl(wint_t wc);-Description
+Description
The iswcntrl function tests for any control wide character. +
7.25.2.1.5 The iswdigit function
-Synopsis
+Synopsis
#include <wctype.h> int iswdigit(wint_t wc);-Description
+Description
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
-Synopsis
+Synopsis
#include <wctype.h> @@ -19621,56 +20235,60 @@ If a length modifier appears with any conversion specifier other than as specifi --Description
+Description
The iswgraph function tests for any wide character for which iswprint is true and iswspace is false.306) -
footnotes
+Footnotes
306) Note that the behavior of the iswgraph and iswpunct functions may differ from their corresponding functions in 7.4.1 with respect to printing, white-space, single-byte execution characters other than ' '. +
7.25.2.1.7 The iswlower function
-Synopsis
+Synopsis
#include <wctype.h> int iswlower(wint_t wc);-Description
+Description
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
-Synopsis
+Synopsis
#include <wctype.h> int iswprint(wint_t wc);-Description
+Description
The iswprint function tests for any printing wide character. +
7.25.2.1.9 The iswpunct function
-Synopsis
+Synopsis
#include <wctype.h> int iswpunct(wint_t wc);-Description
+Description
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
-Synopsis
+Synopsis
#include <wctype.h> @@ -19680,51 +20298,55 @@ If a length modifier appears with any conversion specifier other than as specifi --Description
+Description
The iswspace function tests for any wide character that corresponds to a locale-specific set of white-space wide characters for which none of iswalnum, iswgraph, or iswpunct is true. +
7.25.2.1.11 The iswupper function
-Synopsis
+Synopsis
#include <wctype.h> int iswupper(wint_t wc);-Description
+Description
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
-Synopsis
+Synopsis
#include <wctype.h> int iswxdigit(wint_t wc);-Description
+Description
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
-Synopsis
+Synopsis
#include <wctype.h> int iswctype(wint_t wc, wctype_t desc);-Description
+Description
The iswctype function determines whether the wide character wc has the property described by desc. The current setting of the LC_CTYPE category shall be the same as @@ -19747,50 +20369,54 @@ If a length modifier appears with any conversion specifier other than as specifi iswctype(wc, wctype("upper")) // iswupper(wc) iswctype(wc, wctype("xdigit")) // iswxdigit(wc)
Returns
+Returns
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
-Synopsis
+Synopsis
#include <wctype.h> wctype_t wctype(const char *property);-Description
+Description
The wctype function constructs a value with type wctype_t that describes a class of wide characters identified by the string argument property.
The strings listed in the description of the iswctype function shall be valid in all locales as property arguments to the wctype function. -
Returns
+Returns
If property identifies a valid class of wide characters according to the LC_CTYPE category of the current locale, the wctype function returns a nonzero value that is valid as the second argument to the iswctype function; otherwise, it returns zero. * +
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
+7.25.3.1.1 The towlower function
-Synopsis
+Synopsis
#include <wctype.h> wint_t towlower(wint_t wc);-Description
+Description
The towlower function converts an uppercase letter to a corresponding lowercase letter. -
Returns
+Returns
If the argument is a wide character for which iswupper is true and there are one or more corresponding wide characters, as specified by the current locale, for which @@ -19798,17 +20424,18 @@ If a length modifier appears with any conversion specifier other than as specifi characters (always the same one for any given locale); otherwise, the argument is returned unchanged. +
7.25.3.1.2 The towupper function
-Synopsis
+Synopsis
#include <wctype.h> wint_t towupper(wint_t wc);-Description
+Description
The towupper function converts a lowercase letter to a corresponding uppercase letter. -
Returns
+Returns
If the argument is a wide character for which iswlower is true and there are one or more corresponding wide characters, as specified by the current locale, for which @@ -19816,6 +20443,7 @@ If a length modifier appears with any conversion specifier other than as specifi 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 @@ -19823,14 +20451,15 @@ If a length modifier appears with any conversion specifier other than as specifi previous subclause (7.25.3.1). +
7.25.3.2.1 The towctrans function
-Synopsis
+Synopsis
#include <wctype.h> wint_t towctrans(wint_t wc, wctrans_t desc);-Description
+Description
The towctrans function maps the wide character wc using the mapping described by desc. The current setting of the LC_CTYPE category shall be the same as during the call @@ -19842,38 +20471,41 @@ If a length modifier appears with any conversion specifier other than as specifi towctrans(wc, wctrans("tolower")) // towlower(wc) towctrans(wc, wctrans("toupper")) // towupper(wc)
Returns
+Returns
The towctrans function returns the mapped value of wc using the mapping described by desc. +
7.25.3.2.2 The wctrans function
-Synopsis
+Synopsis
#include <wctype.h> wctrans_t wctrans(const char *property);-Description
+Description
The wctrans function constructs a value with type wctrans_t that describes a mapping between wide characters identified by the string argument property.
The strings listed in the description of the towctrans function shall be valid in all locales as property arguments to the wctrans function. -
Returns
+Returns
If property identifies a valid mapping of wide characters according to the LC_CTYPE category of the current locale, the wctrans function returns a nonzero value that is valid as the second argument to the towctrans function; otherwise, it returns zero. +
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
+Contents +
7.26.1 Complex arithmetic <complex.h>
The function names
@@ -19884,37 +20516,44 @@ If a length modifier appears with any conversion specifier other than as specifi and the same names suffixed with f or l may be added to the declarations in the <complex.h> header. -+7.26.2 Character handling
+Contents +
7.26.2 Character handling <ctype.h>
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
+Contents +
7.26.3 Errors <errno.h>
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
+Contents +
7.26.4 Format conversion of integer types <inttypes.h>
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
+Contents +
7.26.5 Localization <locale.h>
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
+Contents +
7.26.6 Signal handling <signal.h>
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
+Contents +
7.26.7 Boolean type and values <stdbool.h>
The ability to undefine and perhaps then redefine the macros bool, true, and false is an obsolescent feature. -
7.26.8 Integer types
+Contents +
7.26.8 Integer types <stdint.h>
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 @@ -19922,7 +20561,8 @@ If a length modifier appears with any conversion specifier other than as specifi <stdint.h> header. -
7.26.9 Input/output
+Contents +
7.26.9 Input/output <stdio.h>
Lowercase letters may be added to the conversion specifiers and length modifiers in fprintf and fscanf. Other characters may be used in extensions. @@ -19932,17 +20572,20 @@ If a length modifier appears with any conversion specifier other than as specifi 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
+Contents +
7.26.10 General utilities <stdlib.h>
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
+Contents +
7.26.11 String handling <string.h>
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
+Contents +
7.26.12 Extended multibyte and wide character utilities <wchar.h>
Function names that begin with wcs and a lowercase letter may be added to the declarations in the <wchar.h> header. @@ -19950,6 +20593,7 @@ If a length modifier appears with any conversion specifier other than as specifi 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
<wctype.h>@@ -19957,6 +20601,7 @@ If a length modifier appears with any conversion specifier other than as specifi declarations in the <wctype.h> header. +
Annex A
(informative) @@ -19966,8 +20611,10 @@ If a length modifier appears with any conversion specifier other than as specifi NOTE The notation is described in 6.1. ++A.1 Lexical grammar
+A.1.1 Lexical elements
(6.4) token:@@ -19988,6 +20635,7 @@ If a length modifier appears with any conversion specifier other than as specifi each non-white-space character that cannot be one of the above+A.1.2 Keywords
(6.4.1) keyword: one of @@ -20004,6 +20652,7 @@ If a length modifier appears with any conversion specifier other than as specifi else register unionA.1.3 Identifiers
(6.4.2.1) identifier:@@ -20029,6 +20678,7 @@ If a length modifier appears with any conversion specifier other than as specifi 0 1 2 3 4 5 6 7 8 9+A.1.4 Universal character names
(6.4.3) universal-character-name:@@ -20041,6 +20691,7 @@ If a length modifier appears with any conversion specifier other than as specifi hexadecimal-digit hexadecimal-digit+A.1.5 Constants
(6.4.4) constant:@@ -20210,6 +20861,7 @@ If a length modifier appears with any conversion specifier other than as specifi hexadecimal-escape-sequence hexadecimal-digit+A.1.6 String literals
(6.4.5) string-literal:@@ -20229,6 +20881,7 @@ If a length modifier appears with any conversion specifier other than as specifi escape-sequence+A.1.7 Punctuators
(6.4.6) punctuator: one of@@ -20241,6 +20894,7 @@ If a length modifier appears with any conversion specifier other than as specifi <: :> <% %> %: %:%:+A.1.8 Header names
(6.4.7) header-name:@@ -20268,6 +20922,7 @@ If a length modifier appears with any conversion specifier other than as specifi the new-line character and "+A.1.9 Preprocessing numbers
(6.4.8) pp-number: @@ -20283,8 +20938,10 @@ If a length modifier appears with any conversion specifier other than as specifi pp-number .A.2 Phrase structure grammar
+A.2.1 Expressions
(6.5.1) primary-expression:@@ -20412,6 +21069,7 @@ If a length modifier appears with any conversion specifier other than as specifi conditional-expression+A.2.2 Declarations
(6.7) declaration:@@ -20619,6 +21277,7 @@ If a length modifier appears with any conversion specifier other than as specifi . identifier+A.2.3 Statements
(6.8) statement:@@ -20675,6 +21334,7 @@ If a length modifier appears with any conversion specifier other than as specifi return expressionopt ;+A.2.4 External definitions
(6.9) translation-unit:@@ -20696,6 +21356,7 @@ If a length modifier appears with any conversion specifier other than as specifi declaration-list declaration+A.3 Preprocessing directives
(6.10) preprocessing-file:@@ -20784,19 +21445,22 @@ If a length modifier appears with any conversion specifier other than as specifi the new-line character+Annex B
(informative) Library summary-B.1 Diagnostics
+Contents +
B.1 Diagnostics <assert.h>
NDEBUG void assert(scalar expression);-B.2 Complex
+Contents +
B.2 Complex <complex.h>
@@ -20872,7 +21536,8 @@ If a length modifier appears with any conversion specifier other than as specifi long double creall(long double complex z);-B.3 Character handling
+Contents +
B.3 Character handling <ctype.h>
int isalnum(int c); int isalpha(int c); @@ -20890,12 +21555,14 @@ If a length modifier appears with any conversion specifier other than as specifi int toupper(int c);-B.4 Errors
+Contents +
B.4 Errors <errno.h>
EDOM EILSEQ ERANGE errno-B.5 Floating-point environment
+Contents +
B.5 Floating-point environment <fenv.h>
fenv_t FE_OVERFLOW FE_TOWARDZERO @@ -20918,7 +21585,8 @@ If a length modifier appears with any conversion specifier other than as specifi int feupdateenv(const fenv_t *envp);-B.6 Characteristics of floating types
+Contents +
B.6 Characteristics of floating types <float.h>
FLT_ROUNDS DBL_MIN_EXP FLT_MAX FLT_EVAL_METHOD LDBL_MIN_EXP DBL_MAX @@ -20933,7 +21601,8 @@ If a length modifier appears with any conversion specifier other than as specifi FLT_MIN_EXP LDBL_MAX_10_EXP-B.7 Format conversion of integer types
+Contents +
B.7 Format conversion of integer types <inttypes.h>
imaxdiv_t @@ -20960,14 +21629,16 @@ If a length modifier appears with any conversion specifier other than as specifi wchar_t ** restrict endptr, int base);-B.8 Alternative spellings
+Contents +
B.8 Alternative spellings <iso646.h>
and bitor not_eq xor and_eq compl or xor_eq bitand not or_eq-B.9 Sizes of integer types
+Contents +
B.9 Sizes of integer types <limits.h>
CHAR_BIT CHAR_MAX INT_MIN ULONG_MAX SCHAR_MIN MB_LEN_MAX INT_MAX LLONG_MIN @@ -20976,7 +21647,8 @@ If a length modifier appears with any conversion specifier other than as specifi CHAR_MIN USHRT_MAX LONG_MAX-B.10 Localization
+Contents +
B.10 Localization <locale.h>
struct lconv LC_ALL LC_CTYPE LC_NUMERIC NULL LC_COLLATE LC_MONETARY LC_TIME @@ -20984,7 +21656,8 @@ If a length modifier appears with any conversion specifier other than as specifi struct lconv *localeconv(void);-B.11 Mathematics
+Contents +
B.11 Mathematics <math.h>
@@ -21186,14 +21859,16 @@ If a length modifier appears with any conversion specifier other than as specifi int isunordered(real-floating x, real-floating y);B.12 Nonlocal jumps
+Contents +
B.12 Nonlocal jumps <setjmp.h>
jmp_buf int setjmp(jmp_buf env); void longjmp(jmp_buf env, int val);-B.13 Signal handling
+Contents +
B.13 Signal handling <signal.h>
sig_atomic_t SIG_IGN SIGILL SIGTERM SIG_DFL SIGABRT SIGINT @@ -21202,7 +21877,8 @@ If a length modifier appears with any conversion specifier other than as specifi int raise(int sig);-B.14 Variable arguments
+Contents +
B.14 Variable arguments <stdarg.h>
va_list type va_arg(va_list ap, type); @@ -21211,7 +21887,8 @@ If a length modifier appears with any conversion specifier other than as specifi void va_start(va_list ap, parmN);-B.15 Boolean type and values
+Contents +
B.15 Boolean type and values <stdbool.h>
bool @@ -21220,13 +21897,15 @@ If a length modifier appears with any conversion specifier other than as specifi __bool_true_false_are_defined-B.16 Common definitions
+Contents +
B.16 Common definitions <stddef.h>
ptrdiff_t size_t wchar_t NULL offsetof(type, member-designator)-B.17 Integer types
+Contents +
B.17 Integer types <stdint.h>
intN_t INT_LEASTN_MIN PTRDIFF_MAX uintN_t INT_LEASTN_MAX SIG_ATOMIC_MIN @@ -21243,7 +21922,8 @@ If a length modifier appears with any conversion specifier other than as specifi UINTN_MAX PTRDIFF_MIN-B.18 Input/output
+Contents +
B.18 Input/output <stdio.h>
@@ -21323,7 +22003,8 @@ If a length modifier appears with any conversion specifier other than as specifi void perror(const char *s);-B.19 General utilities
+Contents +
B.19 General utilities <stdlib.h>
@@ -21384,7 +22065,8 @@ If a length modifier appears with any conversion specifier other than as specifi const wchar_t * restrict pwcs, size_t n);-B.20 String handling
+Contents +
B.20 String handling <string.h>
size_t @@ -21420,7 +22102,8 @@ If a length modifier appears with any conversion specifier other than as specifi size_t strlen(const char *s);-B.21 Type-generic math
+Contents +
B.21 Type-generic math <tgmath.h>
acos sqrt fmod nextafter asin fabs frexp nexttoward @@ -21439,7 +22122,8 @@ If a length modifier appears with any conversion specifier other than as specifi pow fmin nearbyint creal-B.22 Date and time
+Contents +
B.22 Date and time <time.h>
NULL size_t time_t @@ -21458,7 +22142,8 @@ If a length modifier appears with any conversion specifier other than as specifi const struct tm * restrict timeptr);-B.23 Extended multibyte/wide character utilities
+Contents +
B.23 Extended multibyte/wide character utilities <wchar.h>
@@ -21567,7 +22252,8 @@ If a length modifier appears with any conversion specifier other than as specifi mbstate_t * restrict ps);-B.24 Wide character classification and mapping utilities
+Contents +
B.24 Wide character classification and mapping utilities <wctype.h>
@@ -21592,6 +22278,7 @@ If a length modifier appears with any conversion specifier other than as specifi wctrans_t wctrans(const char *property);+Annex C
(informative) @@ -21618,6 +22305,7 @@ If a length modifier appears with any conversion specifier other than as specifi +Annex D
(normative) @@ -21630,101 +22318,70 @@ If a length modifier appears with any conversion specifier other than as specifi This table is reproduced unchanged from ISO/IEC TR 10176:1998, produced by ISO/IEC JTC 1/SC 22/WG 20, except for the omission of ranges that are part of the basic character sets. - Latin: 00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217, -+
| Latin: | 00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217,
0250-02A8, 1E00-1E9B, 1EA0-1EF9, 207F
-
- Greek: 0386, 0388-038A, 038C, 038E-03A1, 03A3-03CE, 03D0-03D6,
-+ |
(informative)
@@ -21816,12 +22473,14 @@ If a length modifier appears with any conversion specifier other than as specifi
#define LDBL_MIN 1E-37
+
(normative)
IEC 60559 floating-point arithmetic
+This annex specifies C language support for the IEC 60559 floating-point standard. The @@ -21836,6 +22495,7 @@ If a length modifier appears with any conversion specifier other than as specifi a binding between the C language and IEC 60559 is indicated, the IEC 60559-specified behavior is adopted by reference, unless stated otherwise. +
The C floating types match the IEC 60559 formats as follows: @@ -21847,7 +22507,7 @@ If a length modifier appears with any conversion specifier other than as specifi Any non-IEC 60559 extended format used for the long double type shall have more precision than IEC 60559 double and at least the range of IEC 60559 double.308) -
Recommended practice
The long double type should match an IEC 60559 extended format. @@ -21856,7 +22516,7 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
307) ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit and quadruple 128-bit IEC 60559 formats. @@ -21864,17 +22524,19 @@ If a length modifier appears with any conversion specifier other than as specifi all double values. +
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 functions in <math.h> provide designations for IEC 60559 NaNs and infinities. -
Footnotes
309) Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are sufficient for closure of the arithmetic. +
C operators and functions provide IEC 60559 required and recommended facilities as @@ -21953,6 +22615,7 @@ If a length modifier appears with any conversion specifier other than as specifi macros defined in 7.12.3 do not distinguish signaling from quiet NaNs). +
If the floating value is infinite or NaN or if the integral part of the floating value exceeds @@ -21961,7 +22624,7 @@ If a length modifier appears with any conversion specifier other than as specifi integral part is within the range of the integer type raises the ''inexact'' floating-point exception is unspecified.310) -
Footnotes
310) ANSI/IEEE 854, but not IEC 60559 (ANSI/IEEE 754), directly specifies that floating-to-integer conversions raise the ''inexact'' floating-point exception for non-integer in-range values. In those cases where it matters, library functions can be used to effect such conversions with or without raising @@ -21969,6 +22632,7 @@ If a length modifier appears with any conversion specifier other than as specifi <math.h>. +
Conversion from the widest supported IEC 60559 format to decimal with @@ -21990,24 +22654,26 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
311) If the minimum-width IEC 60559 extended format (64 bits of precision) is supported, DECIMAL_DIG shall be at least 21. If IEC 60559 double (53 bits of precision) is the widest IEC 60559 format supported, then DECIMAL_DIG shall be at least 17. (By contrast, LDBL_DIG and DBL_DIG are 18 and 15, respectively, for these formats.) +
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). +
The floating-point environment defined in <fenv.h> includes the IEC 60559 floating- @@ -22015,10 +22681,11 @@ If a length modifier appears with any conversion specifier other than as specifi IEC 60559 dynamic rounding precision and trap enablement modes, if the implementation supports them.312) -
Footnotes
312) This specification does not require dynamic rounding precision nor trap enablement modes. +
IEC 60559 requires that floating-point operations implicitly raise floating-point exception @@ -22027,12 +22694,13 @@ If a length modifier appears with any conversion specifier other than as specifi <fenv.h>) is ''on'', these changes to the floating-point state are treated as side effects which respect sequence points.313) -
Footnotes
313) If the state for the FENV_ACCESS pragma is ''off'', the implementation is free to assume the floating- point control modes will be the default ones and the floating-point status flags will not be tested, which allows certain optimizations (see F.8). +
During translation the IEC 60559 default modes are in effect: @@ -22041,7 +22709,7 @@ If a length modifier appears with any conversion specifier other than as specifi
Recommended practice
The implementation should produce a diagnostic message for each translation-time @@ -22052,13 +22720,14 @@ If a length modifier appears with any conversion specifier other than as specifi floating-point exception, other than ''inexact'';314) the implementation should then proceed with the translation of the program. -
Footnotes
314) As floating constants are converted to appropriate internal representations at translation time, their conversion is subject to default rounding modes and raises no execution-time floating-point exceptions (even where the state of the FENV_ACCESS pragma is ''on''). Library functions, for example strtod, provide execution-time conversion of numeric strings. +
At program startup the floating-point environment is initialized as prescribed by @@ -22071,6 +22740,7 @@ If a length modifier appears with any conversion specifier other than as specifi
An arithmetic constant expression of floating type, other than one in an initializer for an @@ -22101,7 +22771,7 @@ If a length modifier appears with any conversion specifier other than as specifi execution time. -
Footnotes
315) Where the state for the FENV_ACCESS pragma is ''on'', results of inexact expressions like 1.0/3.0 are affected by rounding modes set at execution time, and expressions such as 0.0/0.0 and 1.0/0.0 generate execution-time floating-point exceptions. The programmer can achieve the @@ -22112,6 +22782,7 @@ If a length modifier appears with any conversion specifier other than as specifi +
All computation for automatic initialization is done (as if) at execution time; thus, it is @@ -22150,7 +22821,7 @@ If a length modifier appears with any conversion specifier other than as specifi -
Footnotes
316) Use of float_t and double_t variables increases the likelihood of translation-time computation. For example, the automatic initialization @@ -22160,6 +22831,7 @@ If a length modifier appears with any conversion specifier other than as specifi 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 @@ -22172,11 +22844,13 @@ If a length modifier appears with any conversion specifier other than as specifi ''inexact'', or ''underflow'' and ''inexact''), then ''overflow'' or ''underflow'' is raised before ''inexact''. +
This section identifies code transformations that might subvert IEC 60559-specified behavior, and others that do not. +
Floating-point arithmetic operations and external function calls may entail side effects @@ -22212,65 +22886,44 @@ If a length modifier appears with any conversion specifier other than as specifi if (0 < n) x + 1; +
- x / 2 <-> x * 0.5 Although similar transformations involving inexact -
+
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.
-
- 1 * x and x / 1 -> x The expressions 1 * x, x / 1, and x are equivalent
-+ |
Footnotes
317) Strict support for signaling NaNs -- not required by this specification -- would invalidate these and other transformations that remove arithmetic operators. @@ -22288,12 +22941,13 @@ If a length modifier appears with any conversion specifier other than as specifi for complex z. +
- 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. - x < y -> isless(x,y) (and similarly for <=, >, >=) Though numerically -
+
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. + |
x < y -> isless(x,y) | (and similarly for <=, >, >=) Though numerically equal, these expressions are not equivalent because of side effects when x or y is a NaN and the state of the FENV_ACCESS pragma is ''on''. This transformation, @@ -22301,7 +22955,7 @@ If a length modifier appears with any conversion specifier other than as specifi cause the ''invalid'' floating-point exception for unordered cases, could be performed provided the state of the FENV_ACCESS pragma is ''off''. - + |
@@ -22347,6 +23001,7 @@ If a length modifier appears with any conversion specifier other than as specifi +
The implementation shall honor floating-point exceptions raised by execution-time @@ -22358,11 +23013,12 @@ If a length modifier appears with any conversion specifier other than as specifi precision modes shall assure further that the result of the operation raises no floating- point exception when converted to the semantic type of the operation. -
Footnotes
319) 0 - 0 yields -0 instead of +0 just when the rounding direction is downward. -
Contents +
This subclause contains specifications of <math.h> facilities that are particularly suited for IEC 60559 implementations. @@ -22411,13 +23067,13 @@ If a length modifier appears with any conversion specifier other than as specifi 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 for the sign. -
Footnotes
320) IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on when the floating-point exception is raised. @@ -22425,8 +23081,10 @@ If a length modifier appears with any conversion specifier other than as specifi avoiding them would be too costly. +
Footnotes
322) atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise the ''divide-by-zero'' floating-point exception. +
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. +
On a binary system, ldexp(x, exp) is equivalent to scalbn(x, exp). +
sqrt is fully specified as a basic arithmetic operation in IEC 60559. +
See the sample implementation for ceil in F.9.6.1. +
The nearbyint functions use IEC 60559 rounding according to the current rounding @@ -22823,11 +23523,13 @@ If a length modifier appears with any conversion specifier other than as specifi
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. +
The lrint and llrint functions provide floating-to-integer conversion as prescribed @@ -22838,6 +23540,7 @@ If a length modifier appears with any conversion specifier other than as specifi exception. +
The lround and llround functions differ from the lrint and llrint functions @@ -22874,6 +23578,7 @@ If a length modifier appears with any conversion specifier other than as specifi 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. +
The trunc functions use IEC 60559 rounding toward zero (regardless of the current @@ -22884,8 +23589,10 @@ If a length modifier appears with any conversion specifier other than as specifi
The remainder functions are fully specified as a basic arithmetic operation in IEC 60559. +
The remquo functions follow the specifications for the remainder functions. They have no further specifications special to IEC 60559 implementations. +
copysign is specified in the Appendix to IEC 60559. +
All IEC 60559 implementations support quiet NaNs, in all floating formats. +
No additional requirements beyond those on nextafter. +
No additional requirements. +
If just one argument is a NaN, the fmax functions return the other argument (if both @@ -22960,17 +23677,20 @@ If a length modifier appears with any conversion specifier other than as specifi isnan(y)) ? x : y; } -
Footnotes
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. +
The fmin functions are analogous to the fmax functions (see F.9.9.2). +
(informative)
IEC 60559-compatible complex arithmetic
+This annex supplements annex F to specify complex arithmetic for compatibility with @@ -23003,6 +23725,7 @@ If a length modifier appears with any conversion specifier other than as specifi recommended practice. An implementation that defines __STDC_IEC_559_COMPLEX__ should conform to the specifications in this annex. +
There is a new keyword _Imaginary, which is used to specify imaginary types. It is @@ -23022,6 +23745,7 @@ If a length modifier appears with any conversion specifier other than as specifi
The imaginary type domain comprises the imaginary types. +
A complex or imaginary value with at least one infinite part is regarded as an infinity @@ -23030,13 +23754,16 @@ If a length modifier appears with any conversion specifier other than as specifi a zero if each of its parts is a zero. +
Conversions among imaginary types follow rules analogous to those for real floating types. +
When a value of imaginary type is converted to a real type other than _Bool,324) the @@ -23045,10 +23772,11 @@ If a length modifier appears with any conversion specifier other than as specifi When a value of real type is converted to an imaginary type, the result is a positive imaginary zero. -
Footnotes
When a value of imaginary type is converted to a complex type, the real part of the @@ -23059,6 +23787,7 @@ If a length modifier appears with any conversion specifier other than as specifi complex value is discarded and the value of the imaginary part is converted according to the conversion rules for the corresponding real types. +
The following subclauses supplement 6.5 in order to specify the type of the result for an @@ -23076,8 +23805,9 @@ If a length modifier appears with any conversion specifier other than as specifi +
Semantics
If one operand has real type and the other operand has imaginary type, then the result has imaginary type. If both operands have imaginary type, then the result has real type. (If @@ -23252,13 +23982,14 @@ If a length modifier appears with any conversion specifier other than as specifi with division, provides better roundoff characteristics. -
Footnotes
325) These properties are already implied for those cases covered in the tables, but are required for all cases (at least where the state for CX_LIMITED_RANGE is ''off''). +
Semantics
If both operands have imaginary type, then the result has imaginary type. (If one operand has real type and the other operand has imaginary type, or if either operand has complex @@ -23282,7 +24013,8 @@ If a length modifier appears with any conversion specifier other than as specifi x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v) -
Contents +
The macros
@@ -23309,7 +24041,7 @@ If a length modifier appears with any conversion specifier other than as specifi and the result, the result has the same sign as the argument.The functions are continuous onto both sides of their branch cuts, taking into account the - sign of zero. For example, csqrt(-2 (+-) i0) = (+-)i(sqrt)2. ??? + sign of zero. For example, csqrt(-2 (+-) i0) = (+-)i(sqrt)(2).
Since complex and imaginary values are composed of real values, each function may be regarded as computing real values from real values. Except as noted, the functions treat @@ -23352,13 +24084,15 @@ If a length modifier appears with any conversion specifier other than as specifi -
footnotes
+Footnotes
326) As noted in G.3, a complex value with at least one infinite part is regarded as an infinity even if its other part is a NaN. +
G.6.1 Trigonometric functions
+G.6.1.1 The cacos 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) -
Footnotes
327) This allows cpow( z , c ) to be implemented as cexp(c clog( z )) without precluding implementations that treat special cases more carefully. +
Contents +
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, @@ -23627,29 +24375,34 @@ If a length modifier appears with any conversion specifier other than as specifi atanh(iy) = i atan(y) +
(informative)
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. +
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). +
The LIA-1 data type Boolean is implemented by the C data type bool with values of true and false, all from <stdbool.h>. +
The signed C integer types int, long int, long long int, and the corresponding @@ -23661,19 +24414,21 @@ If a length modifier appears with any conversion specifier other than as specifi only integer divide-by-zero need be detected.
The parameters for the integer data types can be accessed by the following: - maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX,
+ maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_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. +
The integer operations on integer types are the following: +
addI x + y subI x - y mulI x * y @@ -23687,8 +24442,10 @@ If a length modifier appears with any conversion specifier other than as specifi leqI x <= y gtrI x > y geqI x >= y +where x and y are expressions of the same integer type. +
The C floating-point types float, double, and long double are compatible with @@ -23698,24 +24455,31 @@ If a length modifier appears with any conversion specifier other than as specifi operations (see annex F) along with IEC 60559 status flags and traps has LIA-1 conformant types. +
The parameters for a floating point data type can be accessed by the following: +
r FLT_RADIX p FLT_MANT_DIG, DBL_MANT_DIG, LDBL_MANT_DIG emax FLT_MAX_EXP, DBL_MAX_EXP, LDBL_MAX_EXP emin FLT_MIN_EXP, DBL_MIN_EXP, LDBL_MIN_EXP +
The derived constants for the floating point types are accessed by the following: +
fmax FLT_MAX, DBL_MAX, LDBL_MAX fminN FLT_MIN, DBL_MIN, LDBL_MIN epsilon FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON rnd_style FLT_ROUNDS ++
The floating-point operations on floating-point types are the following: +
addF x + y
subF x - y
mulF x * y
@@ -23724,9 +24488,7 @@ If a length modifier appears with any conversion specifier other than as specifi
absF fabsf(x), fabs(x), fabsl(x)
exponentF 1.f+logbf(x), 1.0+logb(x), 1.L+logbl(x)
scaleF scalbnf(x, n), scalbn(x, n), scalbnl(x, n),
-
scalblnf(x, li), scalbln(x, li), scalblnl(x, li)
-
intpartF modff(x, &y), modf(x, &y), modfl(x, &y)
fractpartF modff(x, &y), modf(x, &y), modfl(x, &y)
eqF x == y
@@ -23735,37 +24497,40 @@ If a length modifier appears with any conversion specifier other than as specifi
leqF x <= y
gtrF x > y
geqF x >= y
+
where x and y are expressions of the same floating point type, n is of type int, and li
is of type long int.
+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.
The FLT_ROUNDS parameter can be used to indicate the LIA-1 rounding styles: +
truncate FLT_ROUNDS == 0 nearest FLT_ROUNDS == 1 other FLT_ROUNDS != 0 && FLT_ROUNDS != 1 +provided that an implementation extends FLT_ROUNDS to cover the rounding style used in all relevant LIA-1 operations, not just addition as in C. +
The LIA-1 type conversions are the following type casts: - cvtI' -> I (int)i, (long int)i, (long long int)i,
+ cvtI' -> I (int)i, (long int)i, (long long int)i,
(unsigned int)i, (unsigned long int)i,
(unsigned long long int)i
-
cvtF -> I (int)x, (long int)x, (long long int)x,
-
(unsigned int)x, (unsigned long int)x,
(unsigned long long int)x
-
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
+
In the above conversions from floating to integer, the use of (cast)x can be replaced with (cast)round(x), (cast)rint(x), (cast)nearbyint(x), (cast)trunc(x), @@ -23790,6 +24555,7 @@ If a length modifier appears with any conversion specifier other than as specifi implementation uses round-to-nearest. +
Notification is the process by which a user or program is informed that an exceptional @@ -23797,6 +24563,7 @@ If a length modifier appears with any conversion specifier other than as specifi allows an implementation to cause a notification to occur when any arithmetic operation returns an exceptional value as defined in LIA-1 clause 5. +
LIA-1 requires at least the following two alternatives for handling of notifications: @@ -23817,20 +24584,25 @@ If a length modifier appears with any conversion specifier other than as specifi math library function calls. User-provided signal handlers for SIGFPE allow for trap- and-resume behavior with the same constraint. +
C's <fenv.h> status flags are compatible with the LIA-1 indicators.
The following mapping is for floating-point types: +
undefined FE_INVALID, FE_DIVBYZERO floating_overflow FE_OVERFLOW underflow FE_UNDERFLOW +
The floating-point indicator interrogation and manipulation operations are: +
set_indicators feraiseexcept(i) clear_indicators feclearexcept(i) test_indicators fetestexcept(i) current_indicators fetestexcept(FE_ALL_EXCEPT) +where i is an expression of type int representing a subset of the LIA-1 indicators.
C allows an implementation to provide the following LIA-1 required behavior: at @@ -23842,6 +24614,7 @@ If a length modifier appears with any conversion specifier other than as specifi This documentation makes that distinction because <fenv.h> covers only the floating- point indicators. +
C is compatible with LIA-1's trap requirements for arithmetic operations, but not for @@ -23860,6 +24633,7 @@ If a length modifier appears with any conversion specifier other than as specifi resume, at the programmer's option. +
(informative)
@@ -23905,6 +24679,7 @@ If a length modifier appears with any conversion specifier other than as specifi
+Annex J
(informative)
@@ -23914,6 +24689,7 @@ If a length modifier appears with any conversion specifier other than as specifi
This annex collects some information about portability that appears in this International
Standard.
+J.1 Unspecified behavior
The following are unspecified:
@@ -24025,6 +24801,7 @@ If a length modifier appears with any conversion specifier other than as specifi
G.6.2.3, G.6.2.4, G.6.2.5, G.6.2.6, G.6.3.1, G.6.4.2).
+
J.2 Undefined behavior
The behavior is undefined in the following circumstances:
@@ -24484,11 +25261,13 @@ If a length modifier appears with any conversion specifier other than as specifi
+
J.3 Implementation-defined behavior
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 @@ -24795,6 +25587,7 @@ If a length modifier appears with any conversion specifier other than as specifi +
The following extensions are widely used in many systems, but are not portable to all @@ -24803,6 +25596,7 @@ If a length modifier appears with any conversion specifier other than as specifi extensions are new keywords, extra library functions declared in standard headers, or predefined macros with names that do not begin with an underscore. +
In a hosted environment, the main function receives a third argument, char *envp[], @@ -24810,26 +25604,31 @@ If a length modifier appears with any conversion specifier other than as specifi that provides information about the environment for this execution of the program (5.1.2.2.1). +
Characters other than the underscore _, letters, and digits, that are not part of the basic source character set (such as the dollar sign $, or characters in national character sets) may appear in an identifier (6.4.2). +
All characters in identifiers (with or without external linkage) are significant (6.4.2). +
A function identifier, or the identifier of an object the declaration of which contains the keyword extern, has file scope (6.2.1). +
String literals are modifiable (in which case, identical string literals should denote distinct objects) (6.4.5). +
Additional arithmetic types, such as __int128 or double double, and their @@ -24838,6 +25637,7 @@ If a length modifier appears with any conversion specifier other than as specifi other floating types, and may be used to define float_t or double_t. +
A pointer to an object or to void may be cast to a pointer to a function, allowing data to @@ -24846,17 +25646,20 @@ If a length modifier appears with any conversion specifier other than as specifi 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). +
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). +
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). +
The asm keyword may be used to insert assembly language directly into the translator @@ -24865,18 +25668,21 @@ If a length modifier appears with any conversion specifier other than as specifi 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). +
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). +
If any floating-point status flags are set on normal termination after all calls to functions @@ -24884,11 +25690,13 @@ If a length modifier appears with any conversion specifier other than as specifi writes some diagnostics indicating the fact to the stderr stream, if it is still open, +
Handlers for specific signals are called with extra arguments in addition to the signal number (7.14.1.1). +
Additional mappings from files to streams are supported (7.19.2). @@ -24896,12 +25704,14 @@ If a length modifier appears with any conversion specifier other than as specifi Additional file-opening modes may be specified by characters appended to the mode argument of the fopen function (7.19.5.3). +
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). +
Functions declared in <complex.h> and <math.h> raise SIGFPE to report errors @@ -24909,6 +25719,7 @@ If a length modifier appears with any conversion specifier other than as specifi 7.12). +
- ??? x ???, 3.18 , (comma punctuator), 6.5.2, 6.7, 6.7.2.1, 6.7.2.2, + [^ 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 - ??? x ???, 3.19 - (subtraction operator), 6.5.6, F.3, G.5.2 + [_ x _], 3.19 - (subtraction operator), 6.5.6, F.3, G.5.2 ! (logical negation operator), 6.5.3.3 - (unary minus operator), 6.5.3.3, F.3 != (inequality operator), 6.5.9 -- (postfix decrement operator), 6.3.2.1, 6.5.2.4 # operator, 6.10.3.2 -- (prefix decrement operator), 6.3.2.1, 6.5.3.1 @@ -26119,4 +26931,5 @@ If a length modifier appears with any conversion specifier other than as specifi wctrans_t type, 7.25.1, 7.25.3.2.2 wctype function, 7.25.2.2.1, 7.25.2.2.2+