<!--page 6 -->
<li><a href="#7.26.10"> 7.26.10 General utilities <stdlib.h></a>
<li><a href="#7.26.11"> 7.26.11 String handling <string.h></a>
<!--page 6 -->
<li><a href="#7.26.10"> 7.26.10 General utilities <stdlib.h></a>
<li><a href="#7.26.11"> 7.26.11 String handling <string.h></a>
-<li><a href="#7.26.12"> 7.26.12 Extended multibyte and wide character utilities <wchar.h></a>
-<li><a href="#7.26.13"> 7.26.13 Wide character classification and mapping utilities <wctype.h></a>
+<li><a href="#7.26.12"> 7.26.12 Extended multibyte and wide character utilities <wchar.h></a>
+<li><a href="#7.26.13"> 7.26.13 Wide character classification and mapping utilities <wctype.h></a>
<p><small><a name="note1" href="#note1">1)</a> 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.
</small>
<p><small><a name="note1" href="#note1">1)</a> 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.
</small>
<p><small><a name="note2" href="#note2">2)</a> A strictly conforming program can use conditional features (such as those in <a href="#F">annex F</a>) provided the
use is guarded by a #ifdef directive with the appropriate macro. For example:
<p><small><a name="note2" href="#note2">2)</a> A strictly conforming program can use conditional features (such as those in <a href="#F">annex F</a>) provided the
use is guarded by a #ifdef directive with the appropriate macro. For example:
<p><small><a name="note5" href="#note5">5)</a> 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
<p><small><a name="note5" href="#note5">5)</a> 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
because in those cases where wording in this International Standard describes the behavior for a construct
as being both a constraint error and resulting in undefined behavior, the constraint error shall be diagnosed.
because in those cases where wording in this International Standard describes the behavior for a construct
as being both a constraint error and resulting in undefined behavior, the constraint error shall be diagnosed.
<p><small><a name="note8" href="#note8">8)</a> 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.
<p><small><a name="note8" href="#note8">8)</a> 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.
or with two parameters (referred to here as argc and argv, though any names may be
used, as they are local to the function in which they are declared):
<pre>
or with two parameters (referred to here as argc and argv, though any names may be
used, as they are local to the function in which they are declared):
<pre>
or equivalent;<sup><a href="#note9"><b>9)</b></a></sup> or in some other implementation-defined manner.
<p><!--para 2 -->
If they are declared, the parameters to the main function shall obey the following
or equivalent;<sup><a href="#note9"><b>9)</b></a></sup> or in some other implementation-defined manner.
<p><!--para 2 -->
If they are declared, the parameters to the main function shall obey the following
<p><small><a name="note9" href="#note9">9)</a> 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.
</small>
<p><small><a name="note9" href="#note9">9)</a> 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.
</small>
termination status returned to the host environment is unspecified.
<p><b> Forward references</b>: definition of terms (<a href="#7.1.1">7.1.1</a>), the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
termination status returned to the host environment is unspecified.
<p><b> Forward references</b>: definition of terms (<a href="#7.1.1">7.1.1</a>), the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
<p><small><a name="note10" href="#note10">10)</a> In accordance with <a href="#6.2.4">6.2.4</a>, 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.
</small>
<p><small><a name="note10" href="#note10">10)</a> In accordance with <a href="#6.2.4">6.2.4</a>, 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.
</small>
the ''integer promotions'' require that the abstract machine promote the value of each variable to int size
and then add the two ints and truncate the sum. Provided the addition of two chars can be done without
overflow, or with overflow wrapping silently to produce the correct result, the actual execution need only
the ''integer promotions'' require that the abstract machine promote the value of each variable to int size
and then add the two ints and truncate the sum. Provided the addition of two chars can be done without
overflow, or with overflow wrapping silently to produce the correct result, the actual execution need only
the multiplication may be executed using single-precision arithmetic if the implementation can ascertain
that the result would be the same as if it were executed using double-precision arithmetic (for example, if d
were replaced by the constant 2.0, which has type double).
the multiplication may be executed using single-precision arithmetic if the implementation can ascertain
that the result would be the same as if it were executed using double-precision arithmetic (for example, if d
were replaced by the constant 2.0, which has type double).
x = (x * y) * z; // not equivalent to x *= y * z;
z = (x - y) + y ; // not equivalent to z = x;
z = x + x * y; // not equivalent to z = x * (1.0 + y);
x = (x * y) * z; // not equivalent to x *= y * z;
z = (x - y) + y ; // not equivalent to z = x;
z = x + x * y; // not equivalent to z = x * (1.0 + y);
due to the associativity and precedence of these operators. Thus, the result of the sum (a + 32760) is
next added to b, and that result is then added to 5 which results in the value assigned to a. On a machine in
which overflows produce an explicit trap and in which the range of values representable by an int is
[-32768, +32767], the implementation cannot rewrite this expression as
<pre>
due to the associativity and precedence of these operators. Thus, the result of the sum (a + 32760) is
next added to b, and that result is then added to 5 which results in the value assigned to a. On a machine in
which overflows produce an explicit trap and in which the range of values representable by an int is
[-32768, +32767], the implementation cannot rewrite this expression as
<pre>
since if the values for a and b were, respectively, -32754 and -15, the sum a + b would produce a trap
while the original expression would not; nor can the expression be rewritten either as
<pre>
since if the values for a and b were, respectively, -32754 and -15, the sum a + b would produce a trap
while the original expression would not; nor can the expression be rewritten either as
<pre>
since the values for a and b might have been, respectively, 4 and -8 or -17 and 12. However, on a machine
in which overflow silently generates some value and where positive and negative overflows cancel, the
above expression statement can be rewritten by the implementation in any of the above ways because the
since the values for a and b might have been, respectively, 4 and -8 or -17 and 12. However, on a machine
in which overflow silently generates some value and where positive and negative overflows cancel, the
above expression statement can be rewritten by the implementation in any of the above ways because the
but the actual increment of p can occur at any time between the previous sequence point and the next
sequence point (the ;), and the call to getchar can occur at any point prior to the need of its returned
value.
but the actual increment of p can occur at any time between the previous sequence point and the next
sequence point (the ;), and the call to getchar can occur at any point prior to the need of its returned
value.
<p><small><a name="note11" href="#note11">11)</a> 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
<p><small><a name="note11" href="#note11">11)</a> 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
the following 29 graphic characters
<pre>
! " # % & ' ( ) * + , - . / :
the following 29 graphic characters
<pre>
! " # % & ' ( ) * + , - . / :
the space character, and control characters representing horizontal tab, vertical tab, and
form feed. The representation of each member of the source and execution basic
character sets shall fit in a byte. In both the source and execution basic character sets, the
the space character, and control characters representing horizontal tab, vertical tab, and
form feed. The representation of each member of the source and execution basic
character sets shall fit in a byte. In both the source and execution basic character sets, the
<p><small><a name="note12" href="#note12">12)</a> 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.
</small>
<p><small><a name="note12" href="#note12">12)</a> 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.
</small>
<p><small><a name="note13" href="#note13">13)</a> Implementations should avoid imposing fixed translation limits whenever possible.
</small>
<p><small><a name="note14" href="#note14">14)</a> See ''future language directions'' (<a href="#6.11.3">6.11.3</a>).
<p><small><a name="note13" href="#note13">13)</a> Implementations should avoid imposing fixed translation limits whenever possible.
</small>
<p><small><a name="note14" href="#note14">14)</a> See ''future language directions'' (<a href="#6.11.3">6.11.3</a>).
specified in <a href="#7.18"><stdint.h></a>.
<p><b> Forward references</b>: integer types <a href="#7.18"><stdint.h></a> (<a href="#7.18">7.18</a>).
specified in <a href="#7.18"><stdint.h></a>.
<p><b> Forward references</b>: integer types <a href="#7.18"><stdint.h></a> (<a href="#7.18">7.18</a>).
<p><!--para 1 -->
The values given below shall be replaced by constant expressions suitable for use in #if
preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the
<p><!--para 1 -->
The values given below shall be replaced by constant expressions suitable for use in #if
preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the
(absolute value) to those shown, with the same sign.
<ul>
<li> number of bits for smallest object that is not a bit-field (byte)
(absolute value) to those shown, with the same sign.
<ul>
<li> number of bits for smallest object that is not a bit-field (byte)
UCHAR_MAX.<sup><a href="#note15"><b>15)</b></a></sup> The value UCHAR_MAX shall equal 2<sup>CHAR_BIT</sup> - 1.
<p><b> Forward references</b>: representations of types (<a href="#6.2.6">6.2.6</a>), conditional inclusion (<a href="#6.10.1">6.10.1</a>).
UCHAR_MAX.<sup><a href="#note15"><b>15)</b></a></sup> The value UCHAR_MAX shall equal 2<sup>CHAR_BIT</sup> - 1.
<p><b> Forward references</b>: representations of types (<a href="#6.2.6">6.2.6</a>), conditional inclusion (<a href="#6.10.1">6.10.1</a>).
<p><!--para 1 -->
The characteristics of floating types are defined in terms of a model that describes a
representation of floating-point numbers and values that provide information about an
implementation's floating-point arithmetic.<sup><a href="#note16"><b>16)</b></a></sup> The following parameters are used to
define the model for each floating-point type:
<p><!--para 1 -->
The characteristics of floating types are defined in terms of a model that describes a
representation of floating-point numbers and values that provide information about an
implementation's floating-point arithmetic.<sup><a href="#note16"><b>16)</b></a></sup> The following parameters are used to
define the model for each floating-point type:
<pre>
s sign ((+-)1)
b base or radix of exponent representation (an integer > 1)
e exponent (an integer between a minimum emin and a maximum emax )
p precision (the number of base-b digits in the significand)
<pre>
s sign ((+-)1)
b base or radix of exponent representation (an integer > 1)
e exponent (an integer between a minimum emin and a maximum emax )
p precision (the number of base-b digits in the significand)
A floating-point number (x) is defined by the following model:
<pre>
p
x = s b<sup>e</sup> (Sum) f<sub>k</sub> b<sup>-k</sup> , emin <= e <= emax
A floating-point number (x) is defined by the following model:
<pre>
p
x = s b<sup>e</sup> (Sum) f<sub>k</sub> b<sup>-k</sup> , emin <= e <= emax
operations and constants to the range and precision of the long double
type;
2 evaluate all operations and constants to the range and precision of the
operations and constants to the range and precision of the long double
type;
2 evaluate all operations and constants to the range and precision of the
those shown, with the same sign:
<ul>
<li> radix of exponent representation, b
those shown, with the same sign:
<ul>
<li> radix of exponent representation, b
<li> number of decimal digits, n, such that any floating-point number in the widest
supported floating type with pmax radix b digits can be rounded to a floating-point
number with n decimal digits and back again without change to the value,
<pre>
{ pmax log10 b if b is a power of 10
{
<li> number of decimal digits, n, such that any floating-point number in the widest
supported floating type with pmax radix b digits can be rounded to a floating-point
number with n decimal digits and back again without change to the value,
<pre>
{ pmax log10 b if b is a power of 10
{
<li> number of decimal digits, q, such that any floating-point number with q decimal digits
can be rounded into a floating-point number with p radix b digits and back again
without change to the q decimal digits,
<li> number of decimal digits, q, such that any floating-point number with q decimal digits
can be rounded into a floating-point number with p radix b digits and back again
without change to the q decimal digits,
<li> minimum negative integer such that FLT_RADIX raised to one less than that power is
a normalized floating-point number, emin
<li> minimum negative integer such that FLT_RADIX raised to one less than that power is
a normalized floating-point number, emin
<li> minimum negative integer such that 10 raised to that power is in the range of
normalized floating-point numbers, [^log10 b<sup>emin -1</sup>^]
<li> minimum negative integer such that 10 raised to that power is in the range of
normalized floating-point numbers, [^log10 b<sup>emin -1</sup>^]
<li> maximum integer such that FLT_RADIX raised to one less than that power is a
representable finite floating-point number, emax
<li> maximum integer such that FLT_RADIX raised to one less than that power is a
representable finite floating-point number, emax
<li> maximum integer such that 10 raised to that power is in the range of representable
finite floating-point numbers, [_log10 ((1 - b<sup>-p</sup>)b<sup>emax</sup>)_]
<li> maximum integer such that 10 raised to that power is in the range of representable
finite floating-point numbers, [_log10 ((1 - b<sup>-p</sup>)b<sup>emax</sup>)_]
</ul>
<p><!--para 10 -->
The values given in the following list shall be replaced by constant expressions with
implementation-defined values that are greater than or equal to those shown:
<ul>
<li> maximum representable finite floating-point number, (1 - b<sup>-p</sup>)b<sup>emax</sup>
</ul>
<p><!--para 10 -->
The values given in the following list shall be replaced by constant expressions with
implementation-defined values that are greater than or equal to those shown:
<ul>
<li> maximum representable finite floating-point number, (1 - b<sup>-p</sup>)b<sup>emax</sup>
<li> the difference between 1 and the least value greater than 1 that is representable in the
given floating point type, b<sup>1-p</sup>
<!--page 39 -->
<li> the difference between 1 and the least value greater than 1 that is representable in the
given floating point type, b<sup>1-p</sup>
<!--page 39 -->
<p><!--para 12 -->
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back
should be the identity function.
<p><!--para 12 -->
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back
should be the identity function.
If a type wider than double were supported, then DECIMAL_DIG would be greater than 17. For
example, if the widest type were to use the minimal-width IEC 60559 double-extended format (64 bits of
precision), then DECIMAL_DIG would be 21.
If a type wider than double were supported, then DECIMAL_DIG would be greater than 17. For
example, if the widest type were to use the minimal-width IEC 60559 double-extended format (64 bits of
precision), then DECIMAL_DIG would be 21.
(<a href="#7.20">7.20</a>), input/output <a href="#7.19"><stdio.h></a> (<a href="#7.19">7.19</a>), mathematics <a href="#7.12"><math.h></a> (<a href="#7.12">7.12</a>).
<!--page 41 -->
(<a href="#7.20">7.20</a>), input/output <a href="#7.19"><stdio.h></a> (<a href="#7.19">7.19</a>), mathematics <a href="#7.12"><math.h></a> (<a href="#7.12">7.12</a>).
<!--page 41 -->
<p><small><a name="note16" href="#note16">16)</a> 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.
</small>
<p><small><a name="note16" href="#note16">16)</a> 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.
</small>
definitions are listed on separate lines, except when prefaced by the words ''one of''. An
optional symbol is indicated by the subscript ''opt'', so that
<pre>
definitions are listed on separate lines, except when prefaced by the words ''one of''. An
optional symbol is indicated by the subscript ''opt'', so that
<pre>
indicates an optional expression enclosed in braces.
<p><!--para 2 -->
When syntactic categories are referred to in the main text, they are not italicized and
indicates an optional expression enclosed in braces.
<p><!--para 2 -->
When syntactic categories are referred to in the main text, they are not italicized and
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), external definitions (<a href="#6.9">6.9</a>),
statements (<a href="#6.8">6.8</a>).
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), external definitions (<a href="#6.9">6.9</a>),
statements (<a href="#6.8">6.8</a>).
<p><small><a name="note21" href="#note21">21)</a> There is no linkage between different identifiers.
</small>
<p><small><a name="note22" href="#note22">22)</a> A function declaration can contain the storage-class specifier static only if it is at file scope; see
<p><small><a name="note21" href="#note21">21)</a> There is no linkage between different identifiers.
</small>
<p><small><a name="note22" href="#note22">22)</a> A function declaration can contain the storage-class specifier static only if it is at file scope; see
<p><small><a name="note25" href="#note25">25)</a> 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.
<p><small><a name="note25" href="#note25">25)</a> 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.
qualifiers (if any) of the type from which it is derived.
<p><!--para 27 -->
A pointer to void shall have the same representation and alignment requirements as a
qualifiers (if any) of the type from which it is derived.
<p><!--para 27 -->
A pointer to void shall have the same representation and alignment requirements as a
<p><small><a name="note28" href="#note28">28)</a> Implementation-defined keywords shall have the form of an identifier reserved for any use as
described in <a href="#7.1.3">7.1.3</a>.
</small>
<p><small><a name="note28" href="#note28">28)</a> Implementation-defined keywords shall have the form of an identifier reserved for any use as
described in <a href="#7.1.3">7.1.3</a>.
</small>
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), lvalues, arrays, and function
designators (<a href="#6.3.2.1">6.3.2.1</a>).
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), lvalues, arrays, and function
designators (<a href="#6.3.2.1">6.3.2.1</a>).
<p><small><a name="note40" href="#note40">40)</a> 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
<p><small><a name="note40" href="#note40">40)</a> 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
<p><small><a name="note44" href="#note44">44)</a> 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
<p><small><a name="note44" href="#note44">44)</a> 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
EXAMPLE Given the following two file scope declarations:
<pre>
int f(int (*)(), double (*)[3]);
EXAMPLE Given the following two file scope declarations:
<pre>
int f(int (*)(), double (*)[3]);
<p><small><a name="note46" href="#note46">46)</a> Two types need not be identical to be compatible.
</small>
<p><small><a name="note47" href="#note47">47)</a> As specified in <a href="#6.2.1">6.2.1</a>, the later declaration might hide the prior declaration.
<p><small><a name="note46" href="#note46">46)</a> Two types need not be identical to be compatible.
</small>
<p><small><a name="note47" href="#note47">47)</a> As specified in <a href="#6.2.1">6.2.1</a>, the later declaration might hide the prior declaration.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), structure and union specifiers
(<a href="#6.7.2.1">6.7.2.1</a>).
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), structure and union specifiers
(<a href="#6.7.2.1">6.7.2.1</a>).
<p><small><a name="note48" href="#note48">48)</a> 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.
<p><small><a name="note48" href="#note48">48)</a> 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.
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.
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.
in an implementation-defined manner. If the value being converted is outside the range of
values that can be represented, the behavior is undefined.
in an implementation-defined manner. If the value being converted is outside the range of
values that can be represented, the behavior is undefined.
<p><small><a name="note50" href="#note50">50)</a> 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).
<p><small><a name="note50" href="#note50">50)</a> 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).
the result, whose type domain is the type domain of the operands if they are the same,
and complex otherwise. This pattern is called the usual arithmetic conversions:
<!--page 57 -->
the result, whose type domain is the type domain of the operands if they are the same,
and complex otherwise. This pattern is called the usual arithmetic conversions:
<!--page 57 -->
<ul>
<li> First, if the corresponding real type of either operand is long double, the other
operand is converted, without change of type domain, to a type whose
<ul>
<li> First, if the corresponding real type of either operand is long double, the other
operand is converted, without change of type domain, to a type whose
The values of floating operands and of the results of floating expressions may be
represented in greater precision and range than that required by the type; the types are not
changed thereby.<sup><a href="#note52"><b>52)</b></a></sup>
The values of floating operands and of the results of floating expressions may be
represented in greater precision and range than that required by the type; the types are not
changed thereby.<sup><a href="#note52"><b>52)</b></a></sup>
<p><small><a name="note51" href="#note51">51)</a> 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).
</small>
<p><small><a name="note51" href="#note51">51)</a> 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).
</small>
<p><small><a name="note53" href="#note53">53)</a> 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
<p><small><a name="note53" href="#note53">53)</a> 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
<p><small><a name="note55" href="#note55">55)</a> The macro NULL is defined in <a href="#7.17"><stddef.h></a> (and other headers) as a null pointer constant; see <a href="#7.17">7.17</a>.
</small>
<p><small><a name="note56" href="#note56">56)</a> The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to
<p><small><a name="note55" href="#note55">55)</a> The macro NULL is defined in <a href="#7.17"><stddef.h></a> (and other headers) as a null pointer constant; see <a href="#7.17">7.17</a>.
</small>
<p><small><a name="note56" href="#note56">56)</a> The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to
<p><!--para 2 -->
Each preprocessing token that is converted to a token shall have the lexical form of a
keyword, an identifier, a constant, a string literal, or a punctuator.
<p><!--para 2 -->
Each preprocessing token that is converted to a token shall have the lexical form of a
keyword, an identifier, a constant, a string literal, or a punctuator.
<p><!--para 3 -->
A token is the minimal lexical element of the language in translation phases 7 and 8. The
categories of tokens are: keywords, identifiers, constants, string literals, and punctuators.
<p><!--para 3 -->
A token is the minimal lexical element of the language in translation phases 7 and 8. The
categories of tokens are: keywords, identifiers, constants, string literals, and punctuators.
(<a href="#6.5.3.1">6.5.3.1</a>), preprocessing directives (<a href="#6.10">6.10</a>), preprocessing numbers (<a href="#6.4.8">6.4.8</a>), string literals
(<a href="#6.4.5">6.4.5</a>).
(<a href="#6.5.3.1">6.5.3.1</a>), preprocessing directives (<a href="#6.10">6.10</a>), preprocessing numbers (<a href="#6.4.8">6.4.8</a>), string literals
(<a href="#6.4.5">6.4.5</a>).
<p><small><a name="note58" href="#note58">58)</a> An additional category, placemarkers, is used internally in translation phase 4 (see <a href="#6.10.3.3">6.10.3.3</a>); it cannot
occur in source files.
</small>
<h4><a name="6.4.1" href="#6.4.1">6.4.1 Keywords</a></h4>
<p><small><a name="note58" href="#note58">58)</a> An additional category, placemarkers, is used internally in translation phase 4 (see <a href="#6.10.3.3">6.10.3.3</a>); it cannot
occur in source files.
</small>
<h4><a name="6.4.1" href="#6.4.1">6.4.1 Keywords</a></h4>
<p><!--para 2 -->
The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as
keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for
<p><!--para 2 -->
The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as
keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for
<p><small><a name="note59" href="#note59">59)</a> One possible specification for imaginary types appears in <a href="#G">annex G</a>.
</small>
<h4><a name="6.4.2" href="#6.4.2">6.4.2 Identifiers</a></h4>
<h5><a name="6.4.2.1" href="#6.4.2.1">6.4.2.1 General</a></h5>
<p><small><a name="note59" href="#note59">59)</a> One possible specification for imaginary types appears in <a href="#G">annex G</a>.
</small>
<h4><a name="6.4.2" href="#6.4.2">6.4.2 Identifiers</a></h4>
<h5><a name="6.4.2.1" href="#6.4.2.1">6.4.2.1 General</a></h5>
<p><!--para 2 -->
An identifier is a sequence of nondigit characters (including the underscore _, the
lowercase and uppercase Latin letters, and other characters) and digits, which designates
<p><!--para 2 -->
An identifier is a sequence of nondigit characters (including the underscore _, the
lowercase and uppercase Latin letters, and other characters) and digits, which designates
<p><!--para 5 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of significant initial
characters in an identifier; the limit for an external name (an identifier that has external
<p><!--para 5 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of significant initial
characters in an identifier; the limit for an external name (an identifier that has external
identifiers differ only in nonsignificant characters, the behavior is undefined.
<p><b> Forward references</b>: universal character names (<a href="#6.4.3">6.4.3</a>), macro replacement (<a href="#6.10.3">6.10.3</a>).
identifiers differ only in nonsignificant characters, the behavior is undefined.
<p><b> Forward references</b>: universal character names (<a href="#6.4.3">6.4.3</a>), macro replacement (<a href="#6.10.3">6.10.3</a>).
<p><small><a name="note60" href="#note60">60)</a> 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.
<p><small><a name="note60" href="#note60">60)</a> 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.
<p><!--para 1 -->
The identifier __func__ shall be implicitly declared by the translator as if,
immediately following the opening brace of each function definition, the declaration
<pre>
<p><!--para 1 -->
The identifier __func__ shall be implicitly declared by the translator as if,
immediately following the opening brace of each function definition, the declaration
<pre>
appeared, where function-name is the name of the lexically-enclosing function.<sup><a href="#note61"><b>61)</b></a></sup>
<p><!--para 2 -->
This name is encoded as if the implicit declaration had been written in the source
appeared, where function-name is the name of the lexically-enclosing function.<sup><a href="#note61"><b>61)</b></a></sup>
<p><!--para 2 -->
This name is encoded as if the implicit declaration had been written in the source
<p><small><a name="note61" href="#note61">61)</a> Since the name __func__ is reserved for any use by the implementation (<a href="#7.1.3">7.1.3</a>), if any other
identifier is explicitly declared using the name __func__, the behavior is undefined.
</small>
<h4><a name="6.4.3" href="#6.4.3">6.4.3 Universal character names</a></h4>
<p><small><a name="note61" href="#note61">61)</a> Since the name __func__ is reserved for any use by the implementation (<a href="#7.1.3">7.1.3</a>), if any other
identifier is explicitly declared using the name __func__, the behavior is undefined.
</small>
<h4><a name="6.4.3" href="#6.4.3">6.4.3 Universal character names</a></h4>
<p><!--para 2 -->
A universal character name shall not specify a character whose short identifier is less than
00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through
DFFF inclusive.<sup><a href="#note62"><b>62)</b></a></sup>
<p><!--para 2 -->
A universal character name shall not specify a character whose short identifier is less than
00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through
DFFF inclusive.<sup><a href="#note62"><b>62)</b></a></sup>
<p><!--para 3 -->
Universal character names may be used in identifiers, character constants, and string
literals to designate characters that are not in the basic character set.
<p><!--para 3 -->
Universal character names may be used in identifiers, character constants, and string
literals to designate characters that are not in the basic character set.
<p><!--para 4 -->
The universal character name \Unnnnnnnn designates the character whose eight-digit
short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.<sup><a href="#note63"><b>63)</b></a></sup> Similarly, the universal
<p><!--para 4 -->
The universal character name \Unnnnnnnn designates the character whose eight-digit
short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.<sup><a href="#note63"><b>63)</b></a></sup> Similarly, the universal
<p><small><a name="note62" href="#note62">62)</a> 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).
<p><small><a name="note62" href="#note62">62)</a> 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).
<p><!--para 2 -->
Each constant shall have a type and the value of a constant shall be in the range of
representable values for its type.
<p><!--para 2 -->
Each constant shall have a type and the value of a constant shall be in the range of
representable values for its type.
<p><!--para 3 -->
Each constant has a type, determined by its form and value, as detailed later.
<h5><a name="6.4.4.1" href="#6.4.4.1">6.4.4.1 Integer constants</a></h5>
<p><!--para 3 -->
Each constant has a type, determined by its form and value, as detailed later.
<h5><a name="6.4.4.1" href="#6.4.4.1">6.4.4.1 Integer constants</a></h5>
<p><!--para 2 -->
An integer constant begins with a digit, but has no period or exponent part. It may have a
prefix that specifies its base and a suffix that specifies its type.
<p><!--para 2 -->
An integer constant begins with a digit, but has no period or exponent part. It may have a
prefix that specifies its base and a suffix that specifies its type.
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.
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.
<p><!--para 4 -->
The value of a decimal constant is computed base 10; that of an octal constant, base 8;
that of a hexadecimal constant, base 16. The lexically first digit is the most significant.
<p><!--para 4 -->
The value of a decimal constant is computed base 10; that of an octal constant, base 8;
that of a hexadecimal constant, base 16. The lexically first digit is the most significant.
<p><!--para 2 -->
A floating constant has a significand part that may be followed by an exponent part and a
suffix that specifies its type. The components of the significand part may include a digit
<p><!--para 2 -->
A floating constant has a significand part that may be followed by an exponent part and a
suffix that specifies its type. The components of the significand part may include a digit
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.
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.
<p><!--para 3 -->
The significand part is interpreted as a (decimal or hexadecimal) rational number; the
digit sequence in the exponent part is interpreted as a decimal integer. For decimal
<p><!--para 3 -->
The significand part is interpreted as a (decimal or hexadecimal) rational number; the
digit sequence in the exponent part is interpreted as a decimal integer. For decimal
Floating constants 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.
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.
<p><!--para 6 -->
The implementation should produce a diagnostic message if a hexadecimal constant
cannot be represented exactly in its evaluation format; the implementation should then
<p><!--para 6 -->
The implementation should produce a diagnostic message if a hexadecimal constant
cannot be represented exactly in its evaluation format; the implementation should then
<p><small><a name="note64" href="#note64">64)</a> The specification for the library functions recommends more accurate conversion than required for
floating constants (see <a href="#7.20.1.3">7.20.1.3</a>).
</small>
<h5><a name="6.4.4.3" href="#6.4.4.3">6.4.4.3 Enumeration constants</a></h5>
<p><small><a name="note64" href="#note64">64)</a> The specification for the library functions recommends more accurate conversion than required for
floating constants (see <a href="#7.20.1.3">7.20.1.3</a>).
</small>
<h5><a name="6.4.4.3" href="#6.4.4.3">6.4.4.3 Enumeration constants</a></h5>
<p><!--para 2 -->
An identifier declared as an enumeration constant has type int.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>).
<h5><a name="6.4.4.4" href="#6.4.4.4">6.4.4.4 Character constants</a></h5>
<p><!--para 2 -->
An identifier declared as an enumeration constant has type int.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>).
<h5><a name="6.4.4.4" href="#6.4.4.4">6.4.4.4 Character constants</a></h5>
<p><!--para 2 -->
An integer character constant is a sequence of one or more multibyte characters enclosed
in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the
<p><!--para 2 -->
An integer character constant is a sequence of one or more multibyte characters enclosed
in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the
The single-quote ', the double-quote ", the question-mark ?, the backslash \, and
arbitrary integer values are representable according to the following table of escape
sequences:
The single-quote ', the double-quote ", the question-mark ?, the backslash \, and
arbitrary integer values are representable according to the following table of escape
sequences:
The double-quote " and question-mark ? are representable either by themselves or by the
escape sequences \" and \?, respectively, but the single-quote ' and the backslash \
shall be represented, respectively, by the escape sequences \' and \\.
The double-quote " and question-mark ? are representable either by themselves or by the
escape sequences \" and \?, respectively, but the single-quote ' and the backslash \
shall be represented, respectively, by the escape sequences \' and \\.
<p><!--para 9 -->
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.
<p><!--para 9 -->
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.
<p><!--para 10 -->
An integer character constant has type int. The value of an integer character constant
containing a single character that maps to a single-byte execution character is the
<p><!--para 10 -->
An integer character constant has type int. The value of an integer character constant
containing a single character that maps to a single-byte execution character is the
<p><small><a name="note65" href="#note65">65)</a> The semantics of these characters were discussed in <a href="#5.2.2">5.2.2</a>. If any other character follows a backslash,
the result is not a token and a diagnostic is required. See ''future language directions'' (<a href="#6.11.4">6.11.4</a>).
</small>
<h4><a name="6.4.5" href="#6.4.5">6.4.5 String literals</a></h4>
<p><small><a name="note65" href="#note65">65)</a> The semantics of these characters were discussed in <a href="#5.2.2">5.2.2</a>. If any other character follows a backslash,
the result is not a token and a diagnostic is required. See ''future language directions'' (<a href="#6.11.4">6.11.4</a>).
</small>
<h4><a name="6.4.5" href="#6.4.5">6.4.5 String literals</a></h4>
s-char:
any member of the source character set except
the double-quote ", backslash \, or new-line character
s-char:
any member of the source character set except
the double-quote ", backslash \, or new-line character
<p><!--para 2 -->
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
<p><!--para 2 -->
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
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
\".
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
\".
<p><!--para 4 -->
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
<p><!--para 4 -->
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
produces a single character string literal containing the two characters whose values are '\x12' and '3',
because escape sequences are converted into single members of the execution character set just prior to
adjacent string literal concatenation.
produces a single character string literal containing the two characters whose values are '\x12' and '3',
because escape sequences are converted into single members of the execution character set just prior to
adjacent string literal concatenation.
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>), the mbstowcs
function (<a href="#7.20.8.1">7.20.8.1</a>).
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>), the mbstowcs
function (<a href="#7.20.8.1">7.20.8.1</a>).
<p><small><a name="note66" href="#note66">66)</a> A character string literal need not be a string (see <a href="#7.1.1">7.1.1</a>), because a null character may be embedded in
it by a \0 escape sequence.
</small>
<h4><a name="6.4.6" href="#6.4.6">6.4.6 Punctuators</a></h4>
<p><small><a name="note66" href="#note66">66)</a> A character string literal need not be a string (see <a href="#7.1.1">7.1.1</a>), because a null character may be embedded in
it by a \0 escape sequence.
</small>
<h4><a name="6.4.6" href="#6.4.6">6.4.6 Punctuators</a></h4>
<p><!--para 2 -->
A punctuator is a symbol that has independent syntactic and semantic significance.
Depending on context, it may specify an operation to be performed (which in turn may
<p><!--para 2 -->
A punctuator is a symbol that has independent syntactic and semantic significance.
Depending on context, it may specify an operation to be performed (which in turn may
except for their spelling.<sup><a href="#note68"><b>68)</b></a></sup>
<p><b> Forward references</b>: expressions (<a href="#6.5">6.5</a>), declarations (<a href="#6.7">6.7</a>), preprocessing directives
(<a href="#6.10">6.10</a>), statements (<a href="#6.8">6.8</a>).
except for their spelling.<sup><a href="#note68"><b>68)</b></a></sup>
<p><b> Forward references</b>: expressions (<a href="#6.5">6.5</a>), declarations (<a href="#6.7">6.7</a>), preprocessing directives
(<a href="#6.10">6.10</a>), statements (<a href="#6.8">6.8</a>).
<p><small><a name="note67" href="#note67">67)</a> These tokens are sometimes called ''digraphs''.
</small>
<p><small><a name="note68" href="#note68">68)</a> Thus [ and <: behave differently when ''stringized'' (see <a href="#6.10.3.2">6.10.3.2</a>), but can otherwise be freely
<p><small><a name="note67" href="#note67">67)</a> These tokens are sometimes called ''digraphs''.
</small>
<p><small><a name="note68" href="#note68">68)</a> Thus [ and <: behave differently when ''stringized'' (see <a href="#6.10.3.2">6.10.3.2</a>), but can otherwise be freely
<p><!--para 2 -->
The sequences in both forms of header names are mapped in an implementation-defined
manner to headers or external source file names as specified in <a href="#6.10.2">6.10.2</a>.
<p><!--para 2 -->
The sequences in both forms of header names are mapped in an implementation-defined
manner to headers or external source file names as specified in <a href="#6.10.2">6.10.2</a>.
forms the following sequence of preprocessing tokens (with each individual preprocessing token delimited
by a { on the left and a } on the right).
<pre>
{0x3}{<}{1}{/}{a}{.}{h}{>}{1e2}
{#}{include} {<1/a.h>}
forms the following sequence of preprocessing tokens (with each individual preprocessing token delimited
by a { on the left and a } on the right).
<pre>
{0x3}{<}{1}{/}{a}{.}{h}{>}{1e2}
{#}{include} {<1/a.h>}
<p><small><a name="note69" href="#note69">69)</a> Thus, sequences of characters that resemble escape sequences cause undefined behavior.
</small>
<p><small><a name="note70" href="#note70">70)</a> For an example of a header name preprocessing token used in a #pragma directive, see <a href="#6.10.9">6.10.9</a>.
</small>
<h4><a name="6.4.8" href="#6.4.8">6.4.8 Preprocessing numbers</a></h4>
<p><small><a name="note69" href="#note69">69)</a> Thus, sequences of characters that resemble escape sequences cause undefined behavior.
</small>
<p><small><a name="note70" href="#note70">70)</a> For an example of a header name preprocessing token used in a #pragma directive, see <a href="#6.10.9">6.10.9</a>.
</small>
<h4><a name="6.4.8" href="#6.4.8">6.4.8 Preprocessing numbers</a></h4>
<p><!--para 2 -->
A preprocessing number begins with a digit optionally preceded by a period (.) and may
be followed by valid identifier characters and the character sequences e+, e-, E+, E-,
p+, p-, P+, or P-.
<p><!--para 3 -->
Preprocessing number tokens lexically include all floating and integer constant tokens.
<p><!--para 2 -->
A preprocessing number begins with a digit optionally preceded by a period (.) and may
be followed by valid identifier characters and the character sequences e+, e-, E+, E-,
p+, p-, P+, or P-.
<p><!--para 3 -->
Preprocessing number tokens lexically include all floating and integer constant tokens.
<p><!--para 4 -->
A preprocessing number does not have type or a value; it acquires both after a successful
conversion (as part of translation phase 7) to a floating constant token or an integer
<p><!--para 4 -->
A preprocessing number does not have type or a value; it acquires both after a successful
conversion (as part of translation phase 7) to a floating constant token or an integer
glue(/,/) k(); // syntax error, not comment
/*//*/ l(); // equivalent to l();
m = n//**/o
glue(/,/) k(); // syntax error, not comment
/*//*/ l(); // equivalent to l();
m = n//**/o
<p><small><a name="note72" href="#note72">72)</a> A floating-point status flag is not an object and can be set more than once within an expression.
</small>
<p><small><a name="note73" href="#note73">73)</a> This paragraph renders undefined statement expressions such as
<pre>
i = ++i + 1;
<p><small><a name="note72" href="#note72">72)</a> A floating-point status flag is not an object and can be set more than once within an expression.
</small>
<p><small><a name="note73" href="#note73">73)</a> This paragraph renders undefined statement expressions such as
<pre>
i = ++i + 1;
<p><!--para 2 -->
An identifier is a primary expression, provided it has been declared as designating an
object (in which case it is an lvalue) or a function (in which case it is a function
<p><!--para 2 -->
An identifier is a primary expression, provided it has been declared as designating an
object (in which case it is an lvalue) or a function (in which case it is a function
designator, or a void expression.
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>).
designator, or a void expression.
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>).
<p><small><a name="note79" href="#note79">79)</a> Thus, an undeclared identifier is a violation of the syntax.
</small>
<h4><a name="6.5.2" href="#6.5.2">6.5.2 Postfix operators</a></h4>
<p><small><a name="note79" href="#note79">79)</a> Thus, an undeclared identifier is a violation of the syntax.
</small>
<h4><a name="6.5.2" href="#6.5.2">6.5.2 Postfix operators</a></h4>
<p><!--para 1 -->
One of the expressions shall have type ''pointer to object type'', the other expression shall
have integer type, and the result has type ''type''.
<p><!--para 1 -->
One of the expressions shall have type ''pointer to object type'', the other expression shall
have integer type, and the result has type ''type''.
<p><!--para 2 -->
A postfix expression followed by an expression in square brackets [] is a subscripted
designation of an element of an array object. The definition of the subscript operator []
<p><!--para 2 -->
A postfix expression followed by an expression in square brackets [] is a subscripted
designation of an element of an array object. The definition of the subscript operator []
Here x is a 3 x 5 array of ints; more precisely, x is an array of three element objects, each of which is an
array of five ints. In the expression x[i], which is equivalent to (*((x)+(i))), x is first converted to
a pointer to the initial array of five ints. Then i is adjusted according to the type of x, which conceptually
Here x is a 3 x 5 array of ints; more precisely, x is an array of three element objects, each of which is an
array of five ints. In the expression x[i], which is equivalent to (*((x)+(i))), x is first converted to
a pointer to the initial array of five ints. Then i is adjusted according to the type of x, which conceptually
<p><!--para 1 -->
The expression that denotes the called function<sup><a href="#note80"><b>80)</b></a></sup> shall have type pointer to function
returning void or returning an object type other than an array type.
<p><!--para 1 -->
The expression that denotes the called function<sup><a href="#note80"><b>80)</b></a></sup> shall have type pointer to function
returning void or returning an object type other than an array type.
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.
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.
<p><!--para 3 -->
A postfix expression followed by parentheses () containing a possibly empty, comma-
separated list of expressions is a function call. The postfix expression denotes the called
<p><!--para 3 -->
A postfix expression followed by parentheses () containing a possibly empty, comma-
separated list of expressions is a function call. The postfix expression denotes the called
the functions f1, f2, f3, and f4 may be called in any order. All side effects have to be completed before
the function pointed to by pf[f1()] is called.
<p><b> Forward references</b>: function declarators (including prototypes) (<a href="#6.7.5.3">6.7.5.3</a>), function
definitions (<a href="#6.9.1">6.9.1</a>), the return statement (<a href="#6.8.6.4">6.8.6.4</a>), simple assignment (<a href="#6.5.16.1">6.5.16.1</a>).
the functions f1, f2, f3, and f4 may be called in any order. All side effects have to be completed before
the function pointed to by pf[f1()] is called.
<p><b> Forward references</b>: function declarators (including prototypes) (<a href="#6.7.5.3">6.7.5.3</a>), function
definitions (<a href="#6.9.1">6.9.1</a>), the return statement (<a href="#6.8.6.4">6.8.6.4</a>), simple assignment (<a href="#6.5.16.1">6.5.16.1</a>).
<p><small><a name="note80" href="#note80">80)</a> Most often, this is the result of converting an identifier that is a function designator.
</small>
<p><small><a name="note81" href="#note81">81)</a> A function may change the values of its parameters, but these changes cannot affect the values of the
<p><small><a name="note80" href="#note80">80)</a> Most often, this is the result of converting an identifier that is a function designator.
</small>
<p><small><a name="note81" href="#note81">81)</a> A function may change the values of its parameters, but these changes cannot affect the values of the
<p><!--para 1 -->
The first operand of the . operator shall have a qualified or unqualified structure or union
type, and the second operand shall name a member of that type.
<p><!--para 1 -->
The first operand of the . operator shall have a qualified or unqualified structure or union
type, and the second operand shall name a member of that type.
structure'' or ''pointer to qualified or unqualified union'', and the second operand shall
name a member of the type pointed to.
<!--page 85 -->
structure'' or ''pointer to qualified or unqualified union'', and the second operand shall
name a member of the type pointed to.
<!--page 85 -->
<p><!--para 3 -->
A postfix expression followed by the . operator and an identifier designates a member of
a structure or union object. The value is that of the named member,<sup><a href="#note82"><b>82)</b></a></sup> and is an lvalue if
<p><!--para 3 -->
A postfix expression followed by the . operator and an identifier designates a member of
a structure or union object. The value is that of the named member,<sup><a href="#note82"><b>82)</b></a></sup> and is an lvalue if
<p><b> Forward references</b>: address and indirection operators (<a href="#6.5.3.2">6.5.3.2</a>), structure and union
specifiers (<a href="#6.7.2.1">6.7.2.1</a>).
<!--page 87 -->
<p><b> Forward references</b>: address and indirection operators (<a href="#6.5.3.2">6.5.3.2</a>), structure and union
specifiers (<a href="#6.7.2.1">6.7.2.1</a>).
<!--page 87 -->
<p><small><a name="note82" href="#note82">82)</a> 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 <a href="#6.2.6">6.2.6</a> (a process sometimes called "type
<p><small><a name="note82" href="#note82">82)</a> 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 <a href="#6.2.6">6.2.6</a> (a process sometimes called "type
<p><!--para 1 -->
The operand of the postfix increment or decrement operator shall have qualified or
unqualified real or pointer type and shall be a modifiable lvalue.
<p><!--para 1 -->
The operand of the postfix increment or decrement operator shall have qualified or
unqualified real or pointer type and shall be a modifiable lvalue.
<p><!--para 2 -->
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
<p><!--para 2 -->
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
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), compound assignment (<a href="#6.5.16.2">6.5.16.2</a>).
<h5><a name="6.5.2.5" href="#6.5.2.5">6.5.2.5 Compound literals</a></h5>
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), compound assignment (<a href="#6.5.16.2">6.5.16.2</a>).
<h5><a name="6.5.2.5" href="#6.5.2.5">6.5.2.5 Compound literals</a></h5>
<p><!--para 3 -->
If the compound literal occurs outside the body of a function, the initializer list shall
consist of constant expressions.
<p><!--para 3 -->
If the compound literal occurs outside the body of a function, the initializer list shall
consist of constant expressions.
<p><!--para 4 -->
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
<p><!--para 4 -->
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
initializes p to point to the first element of an array of two ints, the first having the value two and the
second, four. The expressions in this compound literal are required to be constant. The unnamed object
has static storage duration.
initializes p to point to the first element of an array of two ints, the first having the value two and the
second, four. The expressions in this compound literal are required to be constant. The unnamed object
has static storage duration.
p is assigned the address of the first element of an array of two ints, the first having the value previously
pointed to by p and the second, zero. The expressions in this compound literal need not be constant. The
unnamed object has automatic storage duration.
p is assigned the address of the first element of an array of two ints, the first having the value previously
pointed to by p and the second, zero. The expressions in this compound literal need not be constant. The
unnamed object has automatic storage duration.
created using compound literals can be passed to functions without depending on member order:
<pre>
drawline((struct point){.x=1, .y=1},
created using compound literals can be passed to functions without depending on member order:
<pre>
drawline((struct point){.x=1, .y=1},
Or, if drawline instead expected pointers to struct point:
<pre>
drawline(&(struct point){.x=1, .y=1},
Or, if drawline instead expected pointers to struct point:
<pre>
drawline(&(struct point){.x=1, .y=1},
- (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}</pre>
+ (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}
+</pre>
The first always has static storage duration and has type array of char, but need not be modifiable; the last
two have automatic storage duration when they occur within the body of a function, and the first of these
two is modifiable.
The first always has static storage duration and has type array of char, but need not be modifiable; the last
two have automatic storage duration when they occur within the body of a function, and the first of these
two is modifiable.
EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory
and can even be shared. For example,
<pre>
EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory
and can even be shared. For example,
<pre>
<pre>
struct int_list { int car; struct int_list *cdr; };
struct int_list endless_zeros = {0, &endless_zeros};
<pre>
struct int_list { int car; struct int_list *cdr; };
struct int_list endless_zeros = {0, &endless_zeros};
q = p, p = &((struct s){ j++ });
if (j < 2) goto again;
return p == q && q->i == 1;
q = p, p = &((struct s){ j++ });
if (j < 2) goto again;
return p == q && q->i == 1;
The function f() always returns the value 1.
<p><!--para 17 -->
Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the
The function f() always returns the value 1.
<p><!--para 17 -->
Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the
<p><small><a name="note84" href="#note84">84)</a> 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.
</small>
<p><small><a name="note84" href="#note84">84)</a> 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.
</small>
<p><!--para 1 -->
The operand of the prefix increment or decrement operator shall have qualified or
unqualified real or pointer type and shall be a modifiable lvalue.
<p><!--para 1 -->
The operand of the prefix increment or decrement operator shall have qualified or
unqualified real or pointer type and shall be a modifiable lvalue.
<p><!--para 2 -->
The value of the operand of the prefix ++ operator is incremented. The result is the new
value of the operand after incrementation. The expression ++E is equivalent to (E+=1).
<p><!--para 2 -->
The value of the operand of the prefix ++ operator is incremented. The result is the new
value of the operand after incrementation. The expression ++E is equivalent to (E+=1).
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), compound assignment (<a href="#6.5.16.2">6.5.16.2</a>).
<h5><a name="6.5.3.2" href="#6.5.3.2">6.5.3.2 Address and indirection operators</a></h5>
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), compound assignment (<a href="#6.5.16.2">6.5.16.2</a>).
<h5><a name="6.5.3.2" href="#6.5.3.2">6.5.3.2 Address and indirection operators</a></h5>
<p><!--para 1 -->
The operand of the unary & operator shall be either a function designator, the result of a
[] or unary * operator, or an lvalue that designates an object that is not a bit-field and is
not declared with the register storage-class specifier.
<p><!--para 2 -->
The operand of the unary * operator shall have pointer type.
<p><!--para 1 -->
The operand of the unary & operator shall be either a function designator, the result of a
[] or unary * operator, or an lvalue that designates an object that is not a bit-field and is
not declared with the register storage-class specifier.
<p><!--para 2 -->
The operand of the unary * operator shall have pointer type.
<p><!--para 3 -->
The unary & operator yields the address of its operand. If the operand has type ''type'',
the result has type ''pointer to type''. If the operand is the result of a unary * operator,
<p><!--para 3 -->
The unary & operator yields the address of its operand. If the operand has type ''type'',
the result has type ''pointer to type''. If the operand is the result of a unary * operator,
<p><b> Forward references</b>: storage-class specifiers (<a href="#6.7.1">6.7.1</a>), structure and union specifiers
(<a href="#6.7.2.1">6.7.2.1</a>).
<p><b> Forward references</b>: storage-class specifiers (<a href="#6.7.1">6.7.1</a>), structure and union specifiers
(<a href="#6.7.2.1">6.7.2.1</a>).
<p><small><a name="note87" href="#note87">87)</a> 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
<p><small><a name="note87" href="#note87">87)</a> 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
<p><!--para 1 -->
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
integer type; of the ! operator, scalar type.
<p><!--para 1 -->
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
integer type; of the ! operator, scalar type.
<p><!--para 2 -->
The result of the unary + operator is the value of its (promoted) operand. The integer
promotions are performed on the operand, and the result has the promoted type.
<p><!--para 2 -->
The result of the unary + operator is the value of its (promoted) operand. The integer
promotions are performed on the operand, and the result has the promoted type.
<p><!--para 1 -->
The sizeof operator shall not be applied to an expression that has function type or an
incomplete type, to the parenthesized name of such a type, or to an expression that
designates a bit-field member.
<p><!--para 1 -->
The sizeof operator shall not be applied to an expression that has function type or an
incomplete type, to the parenthesized name of such a type, or to an expression that
designates a bit-field member.
<p><!--para 2 -->
The sizeof operator yields the size (in bytes) of its operand, which may be an
expression or the parenthesized name of a type. The size is determined from the type of
<p><!--para 2 -->
The sizeof operator yields the size (in bytes) of its operand, which may be an
expression or the parenthesized name of a type. The size is determined from the type of
The implementation of the alloc function should ensure that its return value is aligned suitably for
conversion to a pointer to double.
<p><!--para 6 -->
EXAMPLE 2 Another use of the sizeof operator is to compute the number of elements in an array:
<pre>
The implementation of the alloc function should ensure that its return value is aligned suitably for
conversion to a pointer to double.
<p><!--para 6 -->
EXAMPLE 2 Another use of the sizeof operator is to compute the number of elements in an array:
<pre>
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>), declarations (<a href="#6.7">6.7</a>),
structure and union specifiers (<a href="#6.7.2.1">6.7.2.1</a>), type names (<a href="#6.7.6">6.7.6</a>), array declarators (<a href="#6.7.5.2">6.7.5.2</a>).
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>), declarations (<a href="#6.7">6.7</a>),
structure and union specifiers (<a href="#6.7.2.1">6.7.2.1</a>), type names (<a href="#6.7.6">6.7.6</a>), array declarators (<a href="#6.7.5.2">6.7.5.2</a>).
<p><small><a name="note88" href="#note88">88)</a> When applied to a parameter declared to have array or function type, the sizeof operator yields the
size of the adjusted (pointer) type (see <a href="#6.9.1">6.9.1</a>).
</small>
<h4><a name="6.5.4" href="#6.5.4">6.5.4 Cast operators</a></h4>
<p><small><a name="note88" href="#note88">88)</a> When applied to a parameter declared to have array or function type, the sizeof operator yields the
size of the adjusted (pointer) type (see <a href="#6.9.1">6.9.1</a>).
</small>
<h4><a name="6.5.4" href="#6.5.4">6.5.4 Cast operators</a></h4>
<p><!--para 2 -->
Unless the type name specifies a void type, the type name shall specify qualified or
unqualified scalar type and the operand shall have scalar type.
<p><!--para 3 -->
Conversions that involve pointers, other than where permitted by the constraints of
<a href="#6.5.16.1">6.5.16.1</a>, shall be specified by means of an explicit cast.
<p><!--para 2 -->
Unless the type name specifies a void type, the type name shall specify qualified or
unqualified scalar type and the operand shall have scalar type.
<p><!--para 3 -->
Conversions that involve pointers, other than where permitted by the constraints of
<a href="#6.5.16.1">6.5.16.1</a>, shall be specified by means of an explicit cast.
<p><!--para 4 -->
Preceding an expression by a parenthesized type name converts the value of the
expression to the named type. This construction is called a cast.<sup><a href="#note89"><b>89)</b></a></sup> A cast that specifies
<p><!--para 4 -->
Preceding an expression by a parenthesized type name converts the value of the
expression to the named type. This construction is called a cast.<sup><a href="#note89"><b>89)</b></a></sup> A cast that specifies
<p><small><a name="note89" href="#note89">89)</a> 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.
</small>
<h4><a name="6.5.5" href="#6.5.5">6.5.5 Multiplicative operators</a></h4>
<p><small><a name="note89" href="#note89">89)</a> 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.
</small>
<h4><a name="6.5.5" href="#6.5.5">6.5.5 Multiplicative operators</a></h4>
<p><!--para 1 -->
<pre>
multiplicative-expression:
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
<p><!--para 1 -->
<pre>
multiplicative-expression:
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
fractional part discarded.<sup><a href="#note90"><b>90)</b></a></sup> If the quotient a/b is representable, the expression
(a/b)*b + a%b shall equal a.
fractional part discarded.<sup><a href="#note90"><b>90)</b></a></sup> If the quotient a/b is representable, the expression
(a/b)*b + a%b shall equal a.
<p><small><a name="note90" href="#note90">90)</a> This is often called ''truncation toward zero''.
</small>
<h4><a name="6.5.6" href="#6.5.6">6.5.6 Additive operators</a></h4>
<p><small><a name="note90" href="#note90">90)</a> This is often called ''truncation toward zero''.
</small>
<h4><a name="6.5.6" href="#6.5.6">6.5.6 Additive operators</a></h4>
<p><!--para 2 -->
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
<p><!--para 2 -->
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
<li> the left operand is a pointer to an object type and the right operand has integer type.
</ul>
(Decrementing is equivalent to subtracting 1.)
<li> the left operand is a pointer to an object type and the right operand has integer type.
</ul>
(Decrementing is equivalent to subtracting 1.)
expression (Q)+1 does not point to an element of the array object.<sup><a href="#note91"><b>91)</b></a></sup>
<p><!--para 10 -->
EXAMPLE Pointer arithmetic is well defined with pointers to variable length array types.
expression (Q)+1 does not point to an element of the array object.<sup><a href="#note91"><b>91)</b></a></sup>
<p><!--para 10 -->
EXAMPLE Pointer arithmetic is well defined with pointers to variable length array types.
If array a in the above example were declared to be an array of known constant size, and pointer p were
declared to be a pointer to an array of the same known constant size (pointing to a), the results would be
the same.
If array a in the above example were declared to be an array of known constant size, and pointer p were
declared to be a pointer to an array of the same known constant size (pointing to a), the results would be
the same.
<p><b> Forward references</b>: array declarators (<a href="#6.7.5.2">6.7.5.2</a>), common definitions <a href="#7.17"><stddef.h></a>
(<a href="#7.17">7.17</a>).
<p><b> Forward references</b>: array declarators (<a href="#6.7.5.2">6.7.5.2</a>), common definitions <a href="#7.17"><stddef.h></a>
(<a href="#7.17">7.17</a>).
<p><small><a name="note91" href="#note91">91)</a> 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
<p><small><a name="note91" href="#note91">91)</a> 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
<p><!--para 3 -->
The integer promotions are performed on each of the operands. The type of the result is
that of the promoted left operand. If the value of the right operand is negative or is
<p><!--para 3 -->
The integer promotions are performed on each of the operands. The type of the result is
that of the promoted left operand. If the value of the right operand is negative or is
resulting value is implementation-defined.
<h4><a name="6.5.8" href="#6.5.8">6.5.8 Relational operators</a></h4>
resulting value is implementation-defined.
<h4><a name="6.5.8" href="#6.5.8">6.5.8 Relational operators</a></h4>
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
<p><small><a name="note92" href="#note92">92)</a> 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''.
</small>
<h4><a name="6.5.9" href="#6.5.9">6.5.9 Equality operators</a></h4>
<p><small><a name="note92" href="#note92">92)</a> 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''.
</small>
<h4><a name="6.5.9" href="#6.5.9">6.5.9 Equality operators</a></h4>
qualified or unqualified version of void; or
<li> one operand is a pointer and the other is a null pointer constant.
</ul>
qualified or unqualified version of void; or
<li> one operand is a pointer and the other is a null pointer constant.
</ul>
<p><!--para 3 -->
The == (equal to) and != (not equal to) operators are analogous to the relational
operators except for their lower precedence.<sup><a href="#note93"><b>93)</b></a></sup> Each of the operators yields 1 if the
<p><!--para 3 -->
The == (equal to) and != (not equal to) operators are analogous to the relational
operators except for their lower precedence.<sup><a href="#note93"><b>93)</b></a></sup> Each of the operators yields 1 if the
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.
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.
<p><small><a name="note93" href="#note93">93)</a> Because of the precedences, a<b == c<d is 1 whenever a<b and c<d have the same truth-value.
</small>
<p><small><a name="note94" href="#note94">94)</a> Two objects may be adjacent in memory because they are adjacent elements of a larger array or
<p><small><a name="note93" href="#note93">93)</a> Because of the precedences, a<b == c<d is 1 whenever a<b and c<d have the same truth-value.
</small>
<p><small><a name="note94" href="#note94">94)</a> Two objects may be adjacent in memory because they are adjacent elements of a larger array or
<p><!--para 3 -->
The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
<p><!--para 3 -->
The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
compares equal to 0, the second operand is not evaluated.
<h4><a name="6.5.14" href="#6.5.14">6.5.14 Logical OR operator</a></h4>
compares equal to 0, the second operand is not evaluated.
<h4><a name="6.5.14" href="#6.5.14">6.5.14 Logical OR operator</a></h4>
<p><!--para 3 -->
The || operator shall yield 1 if either of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
<p><!--para 3 -->
The || operator shall yield 1 if either of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
<li> one operand is a pointer to an object or incomplete type and the other is a pointer to a
qualified or unqualified version of void.
</ul>
<li> one operand is a pointer to an object or incomplete type and the other is a pointer to a
qualified or unqualified version of void.
</ul>
<p><!--para 4 -->
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
<p><!--para 4 -->
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
the third column in the following table is the common type that is the result of a conditional expression in
which the first two columns are the second and third operands (in either order):
<pre>
the third column in the following table is the common type that is the result of a conditional expression in
which the first two columns are the second and third operands (in either order):
<pre>
<p><small><a name="note95" href="#note95">95)</a> A conditional expression does not yield an lvalue.
</small>
<h4><a name="6.5.16" href="#6.5.16">6.5.16 Assignment operators</a></h4>
<p><small><a name="note95" href="#note95">95)</a> A conditional expression does not yield an lvalue.
</small>
<h4><a name="6.5.16" href="#6.5.16">6.5.16 Assignment operators</a></h4>
<p><!--para 3 -->
An assignment operator stores a value in the object designated by the left operand. An
assignment expression has the value of the left operand after the assignment, but is not an
<p><!--para 3 -->
An assignment operator stores a value in the object designated by the left operand. An
assignment expression has the value of the left operand after the assignment, but is not an
<li> the left operand is a pointer and the right is a null pointer constant; or
<li> the left operand has type _Bool and the right is a pointer.
</ul>
<li> the left operand is a pointer and the right is a null pointer constant; or
<li> the left operand has type _Bool and the right is a pointer.
</ul>
<p><!--para 2 -->
In simple assignment (=), the value of the right operand is converted to the type of the
assignment expression and replaces the value stored in the object designated by the left
<p><!--para 2 -->
In simple assignment (=), the value of the right operand is converted to the type of the
assignment expression and replaces the value stored in the object designated by the left
the int value returned by the function may be truncated when stored in the char, and then converted back
to int width prior to the comparison. In an implementation in which ''plain'' char has the same range of
values as unsigned char (and char is narrower than int), the result of the conversion cannot be
the int value returned by the function may be truncated when stored in the char, and then converted back
to int width prior to the comparison. In an implementation in which ''plain'' char has the same range of
values as unsigned char (and char is narrower than int), the result of the conversion cannot be
the value of i is converted to the type of the assignment expression c = i, that is, char type. The value
of the expression enclosed in parentheses is then converted to the type of the outer assignment expression,
that is, long int type.
the value of i is converted to the type of the assignment expression c = i, that is, char type. The value
of the expression enclosed in parentheses is then converted to the type of the outer assignment expression,
that is, long int type.
The first assignment is unsafe because it would allow the following valid code to attempt to change the
value of the const object c.
The first assignment is unsafe because it would allow the following valid code to attempt to change the
value of the const object c.
<p><small><a name="note96" href="#note96">96)</a> The asymmetric appearance of these constraints with respect to type qualifiers is due to the conversion
(specified in <a href="#6.3.2.1">6.3.2.1</a>) 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
<p><small><a name="note96" href="#note96">96)</a> The asymmetric appearance of these constraints with respect to type qualifiers is due to the conversion
(specified in <a href="#6.3.2.1">6.3.2.1</a>) 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
<p><!--para 1 -->
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
<p><!--para 1 -->
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
<p><!--para 2 -->
For the other operators, each operand shall have arithmetic type consistent with those
allowed by the corresponding binary operator.
<p><!--para 2 -->
For the other operators, each operand shall have arithmetic type consistent with those
allowed by the corresponding binary operator.
<p><!--para 3 -->
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.
<!--page 106 -->
<h4><a name="6.5.17" href="#6.5.17">6.5.17 Comma operator</a></h4>
<p><!--para 3 -->
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.
<!--page 106 -->
<h4><a name="6.5.17" href="#6.5.17">6.5.17 Comma operator</a></h4>
<p><!--para 2 -->
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
<p><!--para 2 -->
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
of initializers). On the other hand, it can be used within a parenthesized expression or within the second
expression of a conditional operator in such contexts. In the function call
<pre>
of initializers). On the other hand, it can be used within a parenthesized expression or within the second
expression of a conditional operator in such contexts. In the function call
<pre>
the function has three arguments, the second of which has the value 5.
<p><b> Forward references</b>: initialization (<a href="#6.7.8">6.7.8</a>).
the function has three arguments, the second of which has the value 5.
<p><b> Forward references</b>: initialization (<a href="#6.7.8">6.7.8</a>).
<p><small><a name="note97" href="#note97">97)</a> A comma operator does not yield an lvalue.
</small>
<h3><a name="6.6" href="#6.6">6.6 Constant expressions</a></h3>
<p><small><a name="note97" href="#note97">97)</a> A comma operator does not yield an lvalue.
</small>
<h3><a name="6.6" href="#6.6">6.6 Constant expressions</a></h3>
<p><!--para 2 -->
A constant expression can be evaluated during translation rather than runtime, and
accordingly may be used in any place that a constant may be.
<p><!--para 2 -->
A constant expression can be evaluated during translation rather than runtime, and
accordingly may be used in any place that a constant may be.
<p><!--para 3 -->
Constant expressions shall not contain assignment, increment, decrement, function-call,
or comma operators, except when they are contained within a subexpression that is not
<p><!--para 3 -->
Constant expressions shall not contain assignment, increment, decrement, function-call,
or comma operators, except when they are contained within a subexpression that is not
<p><!--para 5 -->
An expression that evaluates to a constant is required in several contexts. If a floating
expression is evaluated in the translation environment, the arithmetic precision and range
<p><!--para 5 -->
An expression that evaluates to a constant is required in several contexts. If a floating
expression is evaluated in the translation environment, the arithmetic precision and range
<p><small><a name="note98" href="#note98">98)</a> The operand of a sizeof operator is usually not evaluated (<a href="#6.5.3.4">6.5.3.4</a>).
</small>
<p><small><a name="note99" href="#note99">99)</a> An integer constant expression is used to specify the size of a bit-field member of a structure, the
<p><small><a name="note98" href="#note98">98)</a> The operand of a sizeof operator is usually not evaluated (<a href="#6.5.3.4">6.5.3.4</a>).
</small>
<p><small><a name="note99" href="#note99">99)</a> An integer constant expression is used to specify the size of a bit-field member of a structure, the
the expression is a valid integer constant expression with value one.
</small>
<h3><a name="6.7" href="#6.7">6.7 Declarations</a></h3>
the expression is a valid integer constant expression with value one.
</small>
<h3><a name="6.7" href="#6.7">6.7 Declarations</a></h3>
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
<p><!--para 5 -->
A declaration specifies the interpretation and attributes of a set of identifiers. A definition
of an identifier is a declaration for that identifier that:
<p><!--para 5 -->
A declaration specifies the interpretation and attributes of a set of identifiers. A definition
of an identifier is a declaration for that identifier that:
<p><b> Forward references</b>: declarators (<a href="#6.7.5">6.7.5</a>), enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), initialization
(<a href="#6.7.8">6.7.8</a>).
<p><b> Forward references</b>: declarators (<a href="#6.7.5">6.7.5</a>), enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), initialization
(<a href="#6.7.8">6.7.8</a>).
<p><small><a name="note101" href="#note101">101)</a> Function definitions have a different syntax, described in <a href="#6.9.1">6.9.1</a>.
</small>
<h4><a name="6.7.1" href="#6.7.1">6.7.1 Storage-class specifiers</a></h4>
<p><small><a name="note101" href="#note101">101)</a> Function definitions have a different syntax, described in <a href="#6.9.1">6.9.1</a>.
</small>
<h4><a name="6.7.1" href="#6.7.1">6.7.1 Storage-class specifiers</a></h4>
<p><!--para 2 -->
At most, one storage-class specifier may be given in the declaration specifiers in a
declaration.<sup><a href="#note102"><b>102)</b></a></sup>
<p><!--para 2 -->
At most, one storage-class specifier may be given in the declaration specifiers in a
declaration.<sup><a href="#note102"><b>102)</b></a></sup>
<p><!--para 3 -->
The typedef specifier is called a ''storage-class specifier'' for syntactic convenience
only; it is discussed in <a href="#6.7.7">6.7.7</a>. The meanings of the various linkages and storage durations
<p><!--para 3 -->
The typedef specifier is called a ''storage-class specifier'' for syntactic convenience
only; it is discussed in <a href="#6.7.7">6.7.7</a>. The meanings of the various linkages and storage durations
<p><small><a name="note102" href="#note102">102)</a> See ''future language directions'' (<a href="#6.11.5">6.11.5</a>).
</small>
<p><small><a name="note103" href="#note103">103)</a> The implementation may treat any register declaration simply as an auto declaration. However,
<p><small><a name="note102" href="#note102">102)</a> See ''future language directions'' (<a href="#6.11.5">6.11.5</a>).
</small>
<p><small><a name="note103" href="#note103">103)</a> The implementation may treat any register declaration simply as an auto declaration. However,
<p><!--para 2 -->
At least one type specifier shall be given in the declaration specifiers in each declaration,
and in the specifier-qualifier list in each struct declaration and type name. Each list of
<p><!--para 2 -->
At least one type specifier shall be given in the declaration specifiers in each declaration,
and in the specifier-qualifier list in each struct declaration and type name. Each list of
<p><!--para 3 -->
The type specifier _Complex shall not be used if the implementation does not provide
complex types.<sup><a href="#note104"><b>104)</b></a></sup>
<p><!--para 3 -->
The type specifier _Complex shall not be used if the implementation does not provide
complex types.<sup><a href="#note104"><b>104)</b></a></sup>
<p><!--para 4 -->
Specifiers for structures, unions, and enumerations are discussed in <a href="#6.7.2.1">6.7.2.1</a> through
<a href="#6.7.2.3">6.7.2.3</a>. Declarations of typedef names are discussed in <a href="#6.7.7">6.7.7</a>. The characteristics of the
<p><!--para 4 -->
Specifiers for structures, unions, and enumerations are discussed in <a href="#6.7.2.1">6.7.2.1</a> through
<a href="#6.7.2.3">6.7.2.3</a>. Declarations of typedef names are discussed in <a href="#6.7.7">6.7.7</a>. The characteristics of the
<p><small><a name="note104" href="#note104">104)</a> Freestanding implementations are not required to provide complex types. *
</small>
<h5><a name="6.7.2.1" href="#6.7.2.1">6.7.2.1 Structure and union specifiers</a></h5>
<p><small><a name="note104" href="#note104">104)</a> Freestanding implementations are not required to provide complex types. *
</small>
<h5><a name="6.7.2.1" href="#6.7.2.1">6.7.2.1 Structure and union specifiers</a></h5>
<p><!--para 2 -->
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
<p><!--para 2 -->
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
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.
<!--page 114 -->
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.
<!--page 114 -->
<p><!--para 5 -->
As discussed in <a href="#6.2.5">6.2.5</a>, 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
<p><!--para 5 -->
As discussed in <a href="#6.2.5">6.2.5</a>, 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
the structure struct s has a flexible array member d. A typical way to use this is:
<pre>
int m = /* some value */;
the structure struct s has a flexible array member d. A typical way to use this is:
<pre>
int m = /* some value */;
and assuming that the call to malloc succeeds, the object pointed to by p behaves, for most purposes, as if
p had been declared as:
<pre>
and assuming that the call to malloc succeeds, the object pointed to by p behaves, for most purposes, as if
p had been declared as:
<pre>
struct s t1 = { 0 }; // valid
struct s t2 = { 1, { <a href="#4.2">4.2</a> }}; // invalid
t1.n = 4; // valid
struct s t1 = { 0 }; // valid
struct s t2 = { 1, { <a href="#4.2">4.2</a> }}; // invalid
t1.n = 4; // valid
The initialization of t2 is invalid (and violates a constraint) because struct s is treated as if it did not
contain member d. The assignment to t1.d[0] is probably undefined behavior, but it is possible that
<pre>
The initialization of t2 is invalid (and violates a constraint) because struct s is treated as if it did not
contain member d. The assignment to t1.d[0] is probably undefined behavior, but it is possible that
<pre>
in which case the assignment would be legitimate. Nevertheless, it cannot appear in strictly conforming
code.
<p><!--para 19 -->
After the further declaration:
<pre>
in which case the assignment would be legitimate. Nevertheless, it cannot appear in strictly conforming
code.
<p><!--para 19 -->
After the further declaration:
<pre>
and assuming that the calls to malloc succeed, the objects pointed to by s1 and s2 behave, for most
purposes, as if the identifiers had been declared as:
and assuming that the calls to malloc succeed, the objects pointed to by s1 and s2 behave, for most
purposes, as if the identifiers had been declared as:
only copies the member n; if any of the array elements are within the first sizeof (struct s) bytes
of the structure, they might be copied or simply overwritten with indeterminate values.
<p><b> Forward references</b>: tags (<a href="#6.7.2.3">6.7.2.3</a>).
<!--page 117 -->
only copies the member n; if any of the array elements are within the first sizeof (struct s) bytes
of the structure, they might be copied or simply overwritten with indeterminate values.
<p><b> Forward references</b>: tags (<a href="#6.7.2.3">6.7.2.3</a>).
<!--page 117 -->
<p><small><a name="note105" href="#note105">105)</a> A structure or union can not contain a member with a variably modified type because member names
are not ordinary identifiers as defined in <a href="#6.2.3">6.2.3</a>.
</small>
<p><small><a name="note105" href="#note105">105)</a> A structure or union can not contain a member with a variably modified type because member names
are not ordinary identifiers as defined in <a href="#6.2.3">6.2.3</a>.
</small>
<p><!--para 2 -->
The expression that defines the value of an enumeration constant shall be an integer
constant expression that has a value representable as an int.
<p><!--para 2 -->
The expression that defines the value of an enumeration constant shall be an integer
constant expression that has a value representable as an int.
<p><!--para 3 -->
The identifiers in an enumerator list are declared as constants that have type int and
may appear wherever such are permitted.<sup><a href="#note109"><b>109)</b></a></sup> An enumerator with = defines its
<p><!--para 3 -->
The identifiers in an enumerator list are declared as constants that have type int and
may appear wherever such are permitted.<sup><a href="#note109"><b>109)</b></a></sup> An enumerator with = defines its
makes hue the tag of an enumeration, and then declares col as an object that has that type and cp as a
pointer to an object that has that type. The enumerated values are in the set { 0, 1, 20, 21 }.
<p><b> Forward references</b>: tags (<a href="#6.7.2.3">6.7.2.3</a>).
makes hue the tag of an enumeration, and then declares col as an object that has that type and cp as a
pointer to an object that has that type. The enumerated values are in the set { 0, 1, 20, 21 }.
<p><b> Forward references</b>: tags (<a href="#6.7.2.3">6.7.2.3</a>).
<p><small><a name="note109" href="#note109">109)</a> 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.
</small>
<p><small><a name="note109" href="#note109">109)</a> 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.
</small>
<p><!--para 4 -->
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 incomplete<sup><a href="#note111"><b>111)</b></a></sup> until the closing brace
<p><!--para 4 -->
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 incomplete<sup><a href="#note111"><b>111)</b></a></sup> until the closing brace
declares a structure, union, or enumerated type. The list defines the structure content,
<!--page 119 -->
declares a structure, union, or enumerated type. The list defines the structure content,
<!--page 119 -->
specifies a structure or union type and declares the identifier as a tag of that type.<sup><a href="#note113"><b>113)</b></a></sup>
<p><!--para 8 -->
If a type specifier of the form
<pre>
specifies a structure or union type and declares the identifier as a tag of that type.<sup><a href="#note113"><b>113)</b></a></sup>
<p><!--para 8 -->
If a type specifier of the form
<pre>
occurs other than as part of one of the above forms, and no other declaration of the
identifier as a tag is visible, then it declares an incomplete structure or union type, and
occurs other than as part of one of the above forms, and no other declaration of the
identifier as a tag is visible, then it declares an incomplete structure or union type, and
occurs other than as part of one of the above forms, and a declaration of the identifier as a
tag is visible, then it specifies the same type as that other declaration, and does not
redeclare the tag.
occurs other than as part of one of the above forms, and a declaration of the identifier as a
tag is visible, then it specifies the same type as that other declaration, and does not
redeclare the tag.
specifies a structure that contains an integer and two pointers to objects of the same type. Once this
declaration has been given, the declaration
<pre>
specifies a structure that contains an integer and two pointers to objects of the same type. Once this
declaration has been given, the declaration
<pre>
declares s to be an object of the given type and sp to be a pointer to an object of the given type. With
these declarations, the expression sp->left refers to the left struct tnode pointer of the object to
which sp points; the expression s.right->count designates the count member of the right struct
declares s to be an object of the given type and sp to be a pointer to an object of the given type. With
these declarations, the expression sp->left refers to the left struct tnode pointer of the object to
which sp points; the expression s.right->count designates the count member of the right struct
<p><!--para 12 -->
EXAMPLE 2 To illustrate the use of prior declaration of a tag to specify a pair of mutually referential
structures, the declarations
<pre>
struct s1 { struct s2 *s2p; /* ... */ }; // D1
<p><!--para 12 -->
EXAMPLE 2 To illustrate the use of prior declaration of a tag to specify a pair of mutually referential
structures, the declarations
<pre>
struct s1 { struct s2 *s2p; /* ... */ }; // D1
specify a pair of structures that contain pointers to each other. Note, however, that if s2 were already
declared as a tag in an enclosing scope, the declaration D1 would refer to it, not to the tag s2 declared in
D2. To eliminate this context sensitivity, the declaration
<pre>
specify a pair of structures that contain pointers to each other. Note, however, that if s2 were already
declared as a tag in an enclosing scope, the declaration D1 would refer to it, not to the tag s2 declared in
D2. To eliminate this context sensitivity, the declaration
<pre>
may be inserted ahead of D1. This declares a new tag s2 in the inner scope; the declaration D2 then
completes the specification of the new type.
<p><b> Forward references</b>: declarators (<a href="#6.7.5">6.7.5</a>), array declarators (<a href="#6.7.5.2">6.7.5.2</a>), type definitions
(<a href="#6.7.7">6.7.7</a>).
may be inserted ahead of D1. This declares a new tag s2 in the inner scope; the declaration D2 then
completes the specification of the new type.
<p><b> Forward references</b>: declarators (<a href="#6.7.5">6.7.5</a>), array declarators (<a href="#6.7.5.2">6.7.5.2</a>), type definitions
(<a href="#6.7.7">6.7.7</a>).
<p><small><a name="note111" href="#note111">111)</a> 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
<p><small><a name="note111" href="#note111">111)</a> 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
<p><!--para 3 -->
The properties associated with qualified types are meaningful only for expressions that
are lvalues.<sup><a href="#note114"><b>114)</b></a></sup>
<p><!--para 3 -->
The properties associated with qualified types are meaningful only for expressions that
are lvalues.<sup><a href="#note114"><b>114)</b></a></sup>
may be modifiable by hardware, but cannot be assigned to, incremented, or decremented.
may be modifiable by hardware, but cannot be assigned to, incremented, or decremented.
pi = &ncs.mem; // valid
pi = &cs.mem; // violates type constraints for =
pci = &cs.mem; // valid
pi = &ncs.mem; // valid
pi = &cs.mem; // violates type constraints for =
pci = &cs.mem; // valid
<p><small><a name="note114" href="#note114">114)</a> 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.
<p><small><a name="note114" href="#note114">114)</a> 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.
assert that if an object is accessed using one of a, b, or c, and that object is modified anywhere in the
program, then it is never accessed using either of the other two.
assert that if an object is accessed using one of a, b, or c, and that object is modified anywhere in the
program, then it is never accessed using either of the other two.
assert that, during each execution of the function, if an object is accessed through one of the pointer
parameters, then it is not also accessed through the other.
<p><!--para 9 -->
assert that, during each execution of the function, if an object is accessed through one of the pointer
parameters, then it is not also accessed through the other.
<p><!--para 9 -->
extern int d[100];
f(50, d + 50, d); // valid
f(50, d + 1, d); // undefined behavior
extern int d[100];
f(50, d + 50, d); // valid
f(50, d + 1, d); // undefined behavior
illustrate how an unmodified object can be aliased through two restricted pointers. In particular, if a and b
are disjoint arrays, a call of the form h(100, a, b, b) has defined behavior, because array b is not
modified within function h.
illustrate how an unmodified object can be aliased through two restricted pointers. In particular, if a and b
are disjoint arrays, a call of the form h(100, a, b, b) has defined behavior, because array b is not
modified within function h.
function call and an equivalent nested block. With one exception, only ''outer-to-inner'' assignments
between restricted pointers declared in nested blocks have defined behavior.
<!--page 124 -->
function call and an equivalent nested block. With one exception, only ''outer-to-inner'' assignments
between restricted pointers declared in nested blocks have defined behavior.
<!--page 124 -->
The one exception allows the value of a restricted pointer to be carried out of the block in which it (or, more
precisely, the ordinary identifier used to designate it) is declared when that block finishes execution. For
example, this permits new_vector to return a vector.
The one exception allows the value of a restricted pointer to be carried out of the block in which it (or, more
precisely, the ordinary identifier used to designate it) is declared when that block finishes execution. For
example, this permits new_vector to return a vector.
<p><small><a name="note119" href="#note119">119)</a> 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
<p><small><a name="note119" href="#note119">119)</a> 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
<p><!--para 5 -->
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
<p><!--para 5 -->
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
EXAMPLE The declaration of an inline function with external linkage can result in either an external
definition, or a definition available for use only within the translation unit. A file scope declaration with
extern creates an external definition. The following example shows an entire translation unit.
EXAMPLE The declaration of an inline function with external linkage can result in either an external
definition, or a definition available for use only within the translation unit. A file scope declaration with
extern creates an external definition. The following example shows an entire translation unit.
Note that the definition of fahr is an external definition because fahr is also declared with extern, but
the definition of cels is an inline definition. Because cels has external linkage and is referenced, an
external definition has to appear in another translation unit (see <a href="#6.9">6.9</a>); the inline definition and the external
Note that the definition of fahr is an external definition because fahr is also declared with extern, but
the definition of cels is an inline definition. Because cels has external linkage and is referenced, an
external definition has to appear in another translation unit (see <a href="#6.9">6.9</a>); the inline definition and the external
<p><small><a name="note120" href="#note120">120)</a> 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
<p><small><a name="note120" href="#note120">120)</a> 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
<p><!--para 2 -->
Each declarator declares one identifier, and asserts that when an operand of the same
form as the declarator appears in an expression, it designates a function or object with the
<p><!--para 2 -->
Each declarator declares one identifier, and asserts that when an operand of the same
form as the declarator appears in an expression, it designates a function or object with the
where T contains the declaration specifiers that specify a type T (such as int) and D1 is
a declarator that contains an identifier ident. The type specified for the identifier ident in
the various forms of declarator is described inductively using this notation.
<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
where T contains the declaration specifiers that specify a type T (such as int) and D1 is
a declarator that contains an identifier ident. The type specified for the identifier ident in
the various forms of declarator is described inductively using this notation.
<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
then the type specified for ident is T .
<p><!--para 6 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
then the type specified for ident is T .
<p><!--para 6 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
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.
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.
<p><!--para 7 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of pointer, array, and
function declarators that modify an arithmetic, structure, union, or incomplete type, either
<p><!--para 7 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of pointer, array, and
function declarators that modify an arithmetic, structure, union, or incomplete type, either
<p><b> Forward references</b>: array declarators (<a href="#6.7.5.2">6.7.5.2</a>), type definitions (<a href="#6.7.7">6.7.7</a>).
<h5><a name="6.7.5.1" href="#6.7.5.1">6.7.5.1 Pointer declarators</a></h5>
<p><b> Forward references</b>: array declarators (<a href="#6.7.5.2">6.7.5.2</a>), type definitions (<a href="#6.7.7">6.7.7</a>).
<h5><a name="6.7.5.1" href="#6.7.5.1">6.7.5.1 Pointer declarators</a></h5>
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list type-qualifier-list
pointer to T ''. For each type qualifier in the list, ident is a so-qualified pointer.
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list type-qualifier-list
pointer to T ''. For each type qualifier in the list, ident is a so-qualified pointer.
The contents of any object pointed to by ptr_to_constant shall not be modified through that pointer,
but ptr_to_constant itself may be changed to point to another object. Similarly, the contents of the
int pointed to by constant_ptr may be modified, but constant_ptr itself shall always point to the
The contents of any object pointed to by ptr_to_constant shall not be modified through that pointer,
but ptr_to_constant itself may be changed to point to another object. Similarly, the contents of the
int pointed to by constant_ptr may be modified, but constant_ptr itself shall always point to the
declares constant_ptr as an object that has type ''const-qualified pointer to int''.
<h5><a name="6.7.5.2" href="#6.7.5.2">6.7.5.2 Array declarators</a></h5>
declares constant_ptr as an object that has type ''const-qualified pointer to int''.
<h5><a name="6.7.5.2" href="#6.7.5.2">6.7.5.2 Array declarators</a></h5>
<p><!--para 1 -->
In addition to optional type qualifiers and the keyword static, the [ and ] may delimit
an expression or *. If they delimit an expression (which specifies the size of an array), the
<p><!--para 1 -->
In addition to optional type qualifiers and the keyword static, the [ and ] may delimit
an expression or *. If they delimit an expression (which specifies the size of an array), the
An ordinary identifier (as defined in <a href="#6.2.3">6.2.3</a>) 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.
An ordinary identifier (as defined in <a href="#6.2.3">6.2.3</a>) 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.
<p><!--para 3 -->
If, in the declaration ''T D1'', D1 has one of the forms:
<pre>
D[ type-qualifier-list<sub>opt</sub> assignment-expression<sub>opt</sub> ]
D[ static type-qualifier-list<sub>opt</sub> assignment-expression ]
D[ type-qualifier-list static assignment-expression ]
<p><!--para 3 -->
If, in the declaration ''T D1'', D1 has one of the forms:
<pre>
D[ type-qualifier-list<sub>opt</sub> assignment-expression<sub>opt</sub> ]
D[ static type-qualifier-list<sub>opt</sub> assignment-expression ]
D[ type-qualifier-list static assignment-expression ]
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.<sup><a href="#note123"><b>123)</b></a></sup>
(See <a href="#6.7.5.3">6.7.5.3</a> for the meaning of the optional type qualifiers and the keyword static.)
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.<sup><a href="#note123"><b>123)</b></a></sup>
(See <a href="#6.7.5.3">6.7.5.3</a> for the meaning of the optional type qualifiers and the keyword static.)
declares an array of float numbers and an array of pointers to float numbers.
<p><!--para 8 -->
EXAMPLE 2 Note the distinction between the declarations
<pre>
extern int *x;
declares an array of float numbers and an array of pointers to float numbers.
<p><!--para 8 -->
EXAMPLE 2 Note the distinction between the declarations
<pre>
extern int *x;
The first declares x to be a pointer to int; the second declares y to be an array of int of unspecified size
(an incomplete type), the storage for which is defined elsewhere.
The first declares x to be a pointer to int; the second declares y to be an array of int of unspecified size
(an incomplete type), the storage for which is defined elsewhere.
p = a; // invalid: not compatible because 4 != 6
r = c; // compatible, but defined behavior only if
// n == 6 and m == n+1
p = a; // invalid: not compatible because 4 != 6
r = c; // compatible, but defined behavior only if
// n == 6 and m == n+1
int (*s)[m]; // valid: auto pointer to VLA
extern int (*r)[m]; // invalid: r has linkage and points to VLA
static int (*q)[m] = &B; // valid: q is a static block pointer to VLA
int (*s)[m]; // valid: auto pointer to VLA
extern int (*r)[m]; // invalid: r has linkage and points to VLA
static int (*q)[m] = &B; // valid: q is a static block pointer to VLA
<p><b> Forward references</b>: function declarators (<a href="#6.7.5.3">6.7.5.3</a>), function definitions (<a href="#6.9.1">6.9.1</a>),
initialization (<a href="#6.7.8">6.7.8</a>).
<p><b> Forward references</b>: function declarators (<a href="#6.7.5.3">6.7.5.3</a>), function definitions (<a href="#6.9.1">6.9.1</a>),
initialization (<a href="#6.7.8">6.7.8</a>).
<p><small><a name="note123" href="#note123">123)</a> When several ''array of'' specifications are adjacent, a multidimensional array is declared.
</small>
<p><small><a name="note124" href="#note124">124)</a> Thus, * can be used only in function declarations that are not definitions (see <a href="#6.7.5.3">6.7.5.3</a>).
</small>
<h5><a name="6.7.5.3" href="#6.7.5.3">6.7.5.3 Function declarators (including prototypes)</a></h5>
<p><small><a name="note123" href="#note123">123)</a> When several ''array of'' specifications are adjacent, a multidimensional array is declared.
</small>
<p><small><a name="note124" href="#note124">124)</a> Thus, * can be used only in function declarations that are not definitions (see <a href="#6.7.5.3">6.7.5.3</a>).
</small>
<h5><a name="6.7.5.3" href="#6.7.5.3">6.7.5.3 Function declarators (including prototypes)</a></h5>
<p><!--para 4 -->
After adjustment, the parameters in a parameter type list in a function declarator that is
part of a definition of that function shall not have incomplete type.
<p><!--para 4 -->
After adjustment, the parameters in a parameter type list in a function declarator that is
part of a definition of that function shall not have incomplete type.
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list function returning
T ''.
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list function returning
T ''.
declares a function f with no parameters returning an int, a function fip with no parameter specification
returning a pointer to an int, and a pointer pfi to a function with no parameter specification returning an
int. It is especially useful to compare the last two. The binding of *fip() is *(fip()), so that the
declares a function f with no parameters returning an int, a function fip with no parameter specification
returning a pointer to an int, and a pointer pfi to a function with no parameter specification returning an
int. It is especially useful to compare the last two. The binding of *fip() is *(fip()), so that the
declares an array apfi of three pointers to functions returning int. Each of these functions has two
parameters that are pointers to int. The identifiers x and y are declared for descriptive purposes only and
go out of scope at the end of the declaration of apfi.
declares an array apfi of three pointers to functions returning int. Each of these functions has two
parameters that are pointers to int. The identifiers x and y are declared for descriptive purposes only and
go out of scope at the end of the declaration of apfi.
declares a function fpfi that returns a pointer to a function returning an int. The function fpfi has two
parameters: a pointer to a function returning an int (with one parameter of type long int), and an int.
The pointer returned by fpfi points to a function that has one int parameter and accepts zero or more
declares a function fpfi that returns a pointer to a function returning an int. The function fpfi has two
parameters: a pointer to a function returning an int (with one parameter of type long int), and an int.
The pointer returned by fpfi points to a function that has one int parameter and accepts zero or more
for (int j = 0, k = n*m+300; j < k; j++)
// a is a pointer to a VLA with n*m+300 elements
a[i][j] += x;
for (int j = 0, k = n*m+300; j < k; j++)
// a is a pointer to a VLA with n*m+300 elements
a[i][j] += x;
double maximum(int n, int m, double a[n][m]);
double maximum(int n, int m, double a[*][*]);
double maximum(int n, int m, double a[ ][*]);
double maximum(int n, int m, double a[n][m]);
double maximum(int n, int m, double a[*][*]);
double maximum(int n, int m, double a[ ][*]);
as are:
<pre>
void f(double (* restrict a)[5]);
void f(double a[restrict][5]);
void f(double a[restrict 3][5]);
as are:
<pre>
void f(double (* restrict a)[5]);
void f(double a[restrict][5]);
void f(double a[restrict 3][5]);
(Note that the last declaration also specifies that the argument corresponding to a in any call to f must be a
non-null pointer to the first of at least three arrays of 5 doubles, which the others do not.)
<p><b> Forward references</b>: function definitions (<a href="#6.9.1">6.9.1</a>), type names (<a href="#6.7.6">6.7.6</a>).
<!--page 134 -->
(Note that the last declaration also specifies that the argument corresponding to a in any call to f must be a
non-null pointer to the first of at least three arrays of 5 doubles, which the others do not.)
<p><b> Forward references</b>: function definitions (<a href="#6.9.1">6.9.1</a>), type names (<a href="#6.7.6">6.7.6</a>).
<!--page 134 -->
<p><small><a name="note125" href="#note125">125)</a> The macros defined in the <a href="#7.15"><stdarg.h></a> header (<a href="#7.15">7.15</a>) may be used to access arguments that
correspond to the ellipsis.
</small>
<p><small><a name="note125" href="#note125">125)</a> The macros defined in the <a href="#7.15"><stdarg.h></a> header (<a href="#7.15">7.15</a>) may be used to access arguments that
correspond to the ellipsis.
</small>
direct-abstract-declarator<sub>opt</sub> [ type-qualifier-list static
assignment-expression ]
direct-abstract-declarator<sub>opt</sub> [ * ]
direct-abstract-declarator<sub>opt</sub> [ type-qualifier-list static
assignment-expression ]
direct-abstract-declarator<sub>opt</sub> [ * ]
<p><!--para 2 -->
In several contexts, it is necessary to specify a type. This is accomplished using a type
name, which is syntactically a declaration for a function or an object of that type that
<p><!--para 2 -->
In several contexts, it is necessary to specify a type. This is accomplished using a type
name, which is syntactically a declaration for a function or an object of that type that
name respectively the types (a) int, (b) pointer to int, (c) array of three pointers to int, (d) pointer to an
array of three ints, (e) pointer to a variable length array of an unspecified number of ints, (f) function
with no parameter specification returning a pointer to int, (g) pointer to function with no parameters
name respectively the types (a) int, (b) pointer to int, (c) array of three pointers to int, (d) pointer to an
array of three ints, (e) pointer to a variable length array of an unspecified number of ints, (f) function
with no parameter specification returning a pointer to int, (g) pointer to function with no parameters
<p><small><a name="note128" href="#note128">128)</a> 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.
</small>
<h4><a name="6.7.7" href="#6.7.7">6.7.7 Type definitions</a></h4>
<p><small><a name="note128" href="#note128">128)</a> 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.
</small>
<h4><a name="6.7.7" href="#6.7.7">6.7.7 Type definitions</a></h4>
<p><!--para 3 -->
In a declaration whose storage-class specifier is typedef, each declarator defines an
identifier to be a typedef name that denotes the type specified for the identifier in the way
<p><!--para 3 -->
In a declaration whose storage-class specifier is typedef, each declarator defines an
identifier to be a typedef name that denotes the type specified for the identifier in the way
type_ident is defined as a typedef name with the type specified by the declaration
specifiers in T (known as T ), and the identifier in D has the type ''derived-declarator-
type-list T '' where the derived-declarator-type-list is specified by the declarators of D. A
type_ident is defined as a typedef name with the type specified by the declaration
specifiers in T (known as T ), and the identifier in D has the type ''derived-declarator-
type-list T '' where the derived-declarator-type-list is specified by the declarators of D. A
are all valid declarations. The type of distance is int, that of metricp is ''pointer to function with no
parameter specification returning int'', and that of x and z is the specified structure; zp is a pointer to
such a structure. The object distance has a type compatible with any other int object.
are all valid declarations. The type of distance is int, that of metricp is ''pointer to function with no
parameter specification returning int'', and that of x and z is the specified structure; zp is a pointer to
such a structure. The object distance has a type compatible with any other int object.
EXAMPLE 2 After the declarations
<pre>
typedef struct s1 { int x; } t1, *tp1;
EXAMPLE 2 After the declarations
<pre>
typedef struct s1 { int x; } t1, *tp1;
type t1 and the type pointed to by tp1 are compatible. Type t1 is also compatible with type struct
s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int.
<!--page 136 -->
type t1 and the type pointed to by tp1 are compatible. Type t1 is also compatible with type struct
s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int.
<!--page 136 -->
declare a typedef name t with type signed int, a typedef name plain with type int, and a structure
with three bit-field members, one named t that contains values in the range [0, 15], an unnamed const-
qualified bit-field which (if it could be accessed) would contain values in either the range [-15, +15] or
declare a typedef name t with type signed int, a typedef name plain with type int, and a structure
with three bit-field members, one named t that contains values in the range [0, 15], an unnamed const-
qualified bit-field which (if it could be accessed) would contain values in either the range [-15, +15] or
then a function f is declared with type ''function returning signed int with one unnamed parameter
with type pointer to function returning signed int with one unnamed parameter with type signed
int'', and an identifier t with type long int.
then a function f is declared with type ''function returning signed int with one unnamed parameter
with type pointer to function returning signed int with one unnamed parameter with type signed
int'', and an identifier t with type long int.
typedef void fv(int), (*pfv)(int);
void (*signal(int, void (*)(int)))(int);
fv *signal(int, fv *);
typedef void fv(int), (*pfv)(int);
void (*signal(int, void (*)(int)))(int);
fv *signal(int, fv *);
then the current object (defined below) shall have array type and the expression shall be
an integer constant expression. If the array is of unknown size, any nonnegative value is
valid.
<p><!--para 7 -->
If a designator has the form
<pre>
then the current object (defined below) shall have array type and the expression shall be
an integer constant expression. If the array is of unknown size, any nonnegative value is
valid.
<p><!--para 7 -->
If a designator has the form
<pre>
then the current object (defined below) shall have structure or union type and the
identifier shall be the name of a member of that type.
<!--page 138 -->
then the current object (defined below) shall have structure or union type and the
identifier shall be the name of a member of that type.
<!--page 138 -->
EXAMPLE 1 Provided that <a href="#7.3"><complex.h></a> has been #included, the declarations
<pre>
int i = <a href="#3.5">3.5</a>;
EXAMPLE 1 Provided that <a href="#7.3"><complex.h></a> has been #included, the declarations
<pre>
int i = <a href="#3.5">3.5</a>;
defines and initializes x as a one-dimensional array object that has three elements, as no size was specified
and there are three initializers.
defines and initializes x as a one-dimensional array object that has three elements, as no size was specified
and there are three initializers.
is a definition with a fully bracketed initialization: 1, 3, and 5 initialize the first row of y (the array object
y[0]), namely y[0][0], y[0][1], and y[0][2]. Likewise the next two lines initialize y[1] and
y[2]. The initializer ends early, so y[3] is initialized with zeros. Precisely the same effect could have
is a definition with a fully bracketed initialization: 1, 3, and 5 initialize the first row of y (the array object
y[0]), namely y[0][0], y[0][1], and y[0][2]. Likewise the next two lines initialize y[1] and
y[2]. The initializer ends early, so y[3] is initialized with zeros. Precisely the same effect could have
<pre>
int y[4][3] = {
1, 3, 5, 2, 4, 6, 3, 5, 7
<pre>
int y[4][3] = {
1, 3, 5, 2, 4, 6, 3, 5, 7
The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the
next three are taken successively for y[1] and y[2].
The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the
next three are taken successively for y[1] and y[2].
<pre>
int z[4][3] = {
{ 1 }, { 2 }, { 3 }, { 4 }
<pre>
int z[4][3] = {
{ 1 }, { 2 }, { 3 }, { 4 }
initializes the first column of z as specified and initializes the rest with zeros.
<p><!--para 28 -->
EXAMPLE 5 The declaration
<pre>
initializes the first column of z as specified and initializes the rest with zeros.
<p><!--para 28 -->
EXAMPLE 5 The declaration
<pre>
is a definition with an inconsistently bracketed initialization. It defines an array with two element
structures: w[0].a[0] is 1 and w[1].a[0] is 2; all the other elements are zero.
is a definition with an inconsistently bracketed initialization. It defines an array with two element
structures: w[0].a[0] is 1 and w[1].a[0] is 2; all the other elements are zero.
contains an incompletely but consistently bracketed initialization. It defines a three-dimensional array
object: q[0][0][0] is 1, q[1][0][0] is 2, q[1][0][1] is 3, and 4, 5, and 6 initialize
q[2][0][0], q[2][0][1], and q[2][1][0], respectively; all the rest are zero. The initializer for
contains an incompletely but consistently bracketed initialization. It defines a three-dimensional array
object: q[0][0][0] is 1, q[1][0][0] is 2, q[1][0][1] is 3, and 4, 5, and 6 initialize
q[2][0][0], q[2][0][1], and q[2][1][0], respectively; all the rest are zero. The initializer for
in a fully bracketed form.
<p><!--para 30 -->
Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to
in a fully bracketed form.
<p><!--para 30 -->
Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to
- A a = { 1, 2 }, b = { 3, 4, 5 };</pre>
+ A a = { 1, 2 }, b = { 3, 4, 5 };
+</pre>
- int a[] = { 1, 2 }, b[] = { 3, 4, 5 };</pre>
+ int a[] = { 1, 2 }, b[] = { 3, 4, 5 };
+</pre>
defines ''plain'' char array objects s and t whose elements are initialized with character string literals.
This declaration is identical to
<pre>
char s[] = { 'a', 'b', 'c', '\0' },
defines ''plain'' char array objects s and t whose elements are initialized with character string literals.
This declaration is identical to
<pre>
char s[] = { 'a', 'b', 'c', '\0' },
defines p with type ''pointer to char'' and initializes it to point to an object with type ''array of char''
with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to
modify the contents of the array, the behavior is undefined.
defines p with type ''pointer to char'' and initializes it to point to an object with type ''array of char''
with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to
modify the contents of the array, the behavior is undefined.
const char *nm[] = {
[member_two] = "member two",
[member_one] = "member one",
const char *nm[] = {
[member_two] = "member two",
[member_one] = "member one",
<p><!--para 35 -->
EXAMPLE 11 Designators can be used to provide explicit initialization when unadorned initializer lists
might be misunderstood:
<pre>
struct { int a[3], b; } w[] =
<p><!--para 35 -->
EXAMPLE 11 Designators can be used to provide explicit initialization when unadorned initializer lists
might be misunderstood:
<pre>
struct { int a[3], b; } w[] =
<pre>
int a[MAX] = {
1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
<pre>
int a[MAX] = {
1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less
than ten, some of the values provided by the first five initializers will be overridden by the second five.
<p><!--para 38 -->
EXAMPLE 13 Any member of a union can be initialized:
<pre>
In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less
than ten, some of the values provided by the first five initializers will be overridden by the second five.
<p><!--para 38 -->
EXAMPLE 13 Any member of a union can be initialized:
<pre>
<p><small><a name="note129" href="#note129">129)</a> 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.
<p><small><a name="note129" href="#note129">129)</a> 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.
(<a href="#6.8.4">6.8.4</a>), iteration statements (<a href="#6.8.5">6.8.5</a>), the return statement (<a href="#6.8.6.4">6.8.6.4</a>).
<h4><a name="6.8.1" href="#6.8.1">6.8.1 Labeled statements</a></h4>
(<a href="#6.8.4">6.8.4</a>), iteration statements (<a href="#6.8.5">6.8.5</a>), the return statement (<a href="#6.8.6.4">6.8.6.4</a>).
<h4><a name="6.8.1" href="#6.8.1">6.8.1 Labeled statements</a></h4>
<p><!--para 2 -->
A case or default label shall appear only in a switch statement. Further
constraints on such labels are discussed under the switch statement.
<!--page 144 -->
<p><!--para 3 -->
Label names shall be unique within a function.
<p><!--para 2 -->
A case or default label shall appear only in a switch statement. Further
constraints on such labels are discussed under the switch statement.
<!--page 144 -->
<p><!--para 3 -->
Label names shall be unique within a function.
<p><!--para 4 -->
Any statement may be preceded by a prefix that declares an identifier as a label name.
Labels in themselves do not alter the flow of control, which continues unimpeded across
<p><!--para 4 -->
Any statement may be preceded by a prefix that declares an identifier as a label name.
Labels in themselves do not alter the flow of control, which continues unimpeded across
<p><b> Forward references</b>: the goto statement (<a href="#6.8.6.1">6.8.6.1</a>), the switch statement (<a href="#6.8.4.2">6.8.4.2</a>).
<h4><a name="6.8.2" href="#6.8.2">6.8.2 Compound statement</a></h4>
<p><b> Forward references</b>: the goto statement (<a href="#6.8.6.1">6.8.6.1</a>), the switch statement (<a href="#6.8.4.2">6.8.4.2</a>).
<h4><a name="6.8.2" href="#6.8.2">6.8.2 Compound statement</a></h4>
<p><!--para 2 -->
A compound statement is a block.
<h4><a name="6.8.3" href="#6.8.3">6.8.3 Expression and null statements</a></h4>
<p><!--para 2 -->
A compound statement is a block.
<h4><a name="6.8.3" href="#6.8.3">6.8.3 Expression and null statements</a></h4>
<p><!--para 2 -->
The expression in an expression statement is evaluated as a void expression for its side
effects.<sup><a href="#note134"><b>134)</b></a></sup>
<p><!--para 2 -->
The expression in an expression statement is evaluated as a void expression for its side
effects.<sup><a href="#note134"><b>134)</b></a></sup>
<p><small><a name="note134" href="#note134">134)</a> Such as assignments, and function calls which have side effects.
</small>
<h4><a name="6.8.4" href="#6.8.4">6.8.4 Selection statements</a></h4>
<p><small><a name="note134" href="#note134">134)</a> Such as assignments, and function calls which have side effects.
</small>
<h4><a name="6.8.4" href="#6.8.4">6.8.4 Selection statements</a></h4>
subset of the scope of the selection statement.
<h5><a name="6.8.4.1" href="#6.8.4.1">6.8.4.1 The if statement</a></h5>
subset of the scope of the selection statement.
<h5><a name="6.8.4.1" href="#6.8.4.1">6.8.4.1 The if statement</a></h5>
<p><!--para 2 -->
In both forms, the first substatement is executed if the expression compares unequal to 0.
In the else form, the second substatement is executed if the expression compares equal
<p><!--para 2 -->
In both forms, the first substatement is executed if the expression compares unequal to 0.
In the else form, the second substatement is executed if the expression compares equal
(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.)
(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.)
<p><!--para 4 -->
A switch statement causes control to jump to, into, or past the statement that is the
switch body, depending on the value of a controlling expression, and on the presence of a
<p><!--para 4 -->
A switch statement causes control to jump to, into, or past the statement that is the
switch body, depending on the value of a controlling expression, and on the presence of a
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.
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.
the object whose identifier is i exists with automatic storage duration (within the block) but is never
initialized, and thus if the controlling expression has a nonzero value, the call to the printf function will
access an indeterminate value. Similarly, the call to the function f cannot be reached.
the object whose identifier is i exists with automatic storage duration (within the block) but is never
initialized, and thus if the controlling expression has a nonzero value, the call to the printf function will
access an indeterminate value. Similarly, the call to the function f cannot be reached.
<p><small><a name="note135" href="#note135">135)</a> 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.
</small>
<h4><a name="6.8.5" href="#6.8.5">6.8.5 Iteration statements</a></h4>
<p><small><a name="note135" href="#note135">135)</a> 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.
</small>
<h4><a name="6.8.5" href="#6.8.5">6.8.5 Iteration statements</a></h4>
<p><!--para 1 -->
<pre>
iteration-statement:
while ( expression ) statement
do statement while ( expression ) ;
for ( expression<sub>opt</sub> ; expression<sub>opt</sub> ; expression<sub>opt</sub> ) statement
<p><!--para 1 -->
<pre>
iteration-statement:
while ( expression ) statement
do statement while ( expression ) ;
for ( expression<sub>opt</sub> ; expression<sub>opt</sub> ; expression<sub>opt</sub> ) statement
<p><!--para 2 -->
The controlling expression of an iteration statement shall have scalar type.
<p><!--para 3 -->
The declaration part of a for statement shall only declare identifiers for objects having
storage class auto or register.
<p><!--para 2 -->
The controlling expression of an iteration statement shall have scalar type.
<p><!--para 3 -->
The declaration part of a for statement shall only declare identifiers for objects having
storage class auto or register.
<p><!--para 4 -->
An iteration statement causes a statement called the loop body to be executed repeatedly
until the controlling expression compares equal to 0. The repetition occurs regardless of
<p><!--para 4 -->
An iteration statement causes a statement called the loop body to be executed repeatedly
until the controlling expression compares equal to 0. The repetition occurs regardless of
<p><small><a name="note136" href="#note136">136)</a> 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.
</small>
<p><small><a name="note136" href="#note136">136)</a> 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.
</small>
behaves as follows: The expression expression-2 is the controlling expression that is
evaluated before each execution of the loop body. The expression expression-3 is
evaluated as a void expression after each execution of the loop body. If clause-1 is a
behaves as follows: The expression expression-2 is the controlling expression that is
evaluated before each execution of the loop body. The expression expression-3 is
evaluated as a void expression after each execution of the loop body. If clause-1 is a
<p><small><a name="note137" href="#note137">137)</a> 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
<p><small><a name="note137" href="#note137">137)</a> 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
<p><!--para 1 -->
The identifier in a goto statement shall name a label located somewhere in the enclosing
function. A goto statement shall not jump from outside the scope of an identifier having
a variably modified type to inside the scope of that identifier.
<p><!--para 1 -->
The identifier in a goto statement shall name a label located somewhere in the enclosing
function. A goto statement shall not jump from outside the scope of an identifier having
a variably modified type to inside the scope of that identifier.
<p><!--para 2 -->
A goto statement causes an unconditional jump to the statement prefixed by the named
label in the enclosing function.
<p><!--para 2 -->
A goto statement causes an unconditional jump to the statement prefixed by the named
label in the enclosing function.
<p><!--para 2 -->
A continue statement causes a jump to the loop-continuation portion of the smallest
enclosing iteration statement; that is, to the end of the loop body. More precisely, in each
<p><!--para 2 -->
A continue statement causes a jump to the loop-continuation portion of the smallest
enclosing iteration statement; that is, to the end of the loop body. More precisely, in each
continue; continue; continue;
/* ... */ /* ... */ /* ... */
contin: ; contin: ; contin: ;
continue; continue; continue;
/* ... */ /* ... */ /* ... */
contin: ; contin: ; contin: ;
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;.<sup><a href="#note138"><b>138)</b></a></sup>
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;.<sup><a href="#note138"><b>138)</b></a></sup>
<p><small><a name="note138" href="#note138">138)</a> Following the contin: label is a null statement.
</small>
<h5><a name="6.8.6.3" href="#6.8.6.3">6.8.6.3 The break statement</a></h5>
<p><small><a name="note138" href="#note138">138)</a> Following the contin: label is a null statement.
</small>
<h5><a name="6.8.6.3" href="#6.8.6.3">6.8.6.3 The break statement</a></h5>
<p><!--para 1 -->
A return statement with an expression shall not appear in a function whose return type
is void. A return statement without an expression shall only appear in a function
whose return type is void.
<p><!--para 1 -->
A return statement with an expression shall not appear in a function whose return type
is void. A return statement without an expression shall only appear in a function
whose return type is void.
<p><!--para 2 -->
A return statement terminates execution of the current function and returns control to
its caller. A function may have any number of return statements.
<p><!--para 2 -->
A return statement terminates execution of the current function and returns control to
its caller. A function may have any number of return statements.
there is no undefined behavior, although there would be if the assignment were done directly (without using
a function call to fetch the value).
there is no undefined behavior, although there would be if the assignment were done directly (without using
a function call to fetch the value).
<p><small><a name="note139" href="#note139">139)</a> The return statement is not an assignment. The overlap restriction of subclause <a href="#6.5.16.1">6.5.16.1</a> 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
<p><small><a name="note139" href="#note139">139)</a> The return statement is not an assignment. The overlap restriction of subclause <a href="#6.5.16.1">6.5.16.1</a> 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
<p><!--para 2 -->
The storage-class specifiers auto and register shall not appear in the declaration
specifiers in an external declaration.
<p><!--para 2 -->
The storage-class specifiers auto and register shall not appear in the declaration
specifiers in an external declaration.
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.
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.
<p><!--para 4 -->
As discussed in <a href="#5.1.1.1">5.1.1.1</a>, the unit of program text after preprocessing is a translation unit,
which consists of a sequence of external declarations. These are described as ''external''
<p><!--para 4 -->
As discussed in <a href="#5.1.1.1">5.1.1.1</a>, the unit of program text after preprocessing is a translation unit,
which consists of a sequence of external declarations. These are described as ''external''
<p><small><a name="note140" href="#note140">140)</a> Thus, if an identifier declared with external linkage is not used in an expression, there need be no
external definition for it.
</small>
<h4><a name="6.9.1" href="#6.9.1">6.9.1 Function definitions</a></h4>
<p><small><a name="note140" href="#note140">140)</a> Thus, if an identifier declared with external linkage is not used in an expression, there need be no
external definition for it.
</small>
<h4><a name="6.9.1" href="#6.9.1">6.9.1 Function definitions</a></h4>
<p><!--para 2 -->
The identifier declared in a function definition (which is the name of the function) shall
have a function type, as specified by the declarator portion of the function definition.<sup><a href="#note141"><b>141)</b></a></sup>
<p><!--para 2 -->
The identifier declared in a function definition (which is the name of the function) shall
have a function type, as specified by the declarator portion of the function definition.<sup><a href="#note141"><b>141)</b></a></sup>
<p><!--para 7 -->
The declarator in a function definition specifies the name of the function being defined
and the identifiers of its parameters. If the declarator includes a parameter type list, the
<p><!--para 7 -->
The declarator in a function definition specifies the name of the function being defined
and the identifiers of its parameters. If the declarator includes a parameter type list, the
Here int a, b; is the declaration list for the parameters. The difference between these two definitions is
that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls
to the function, whereas the second form does not.
Here int a, b; is the declaration list for the parameters. The difference between these two definitions is
that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls
to the function, whereas the second form does not.
Then the definition of g might read
<pre>
void g(int (*funcp)(void))
{
/* ... */
(*funcp)(); /* or funcp(); ... */
Then the definition of g might read
<pre>
void g(int (*funcp)(void))
{
/* ... */
(*funcp)(); /* or funcp(); ... */
F *e(void) { /* ... */ } // e returns a pointer to a function
F *((e))(void) { /* ... */ } // same: parentheses irrelevant
int (*fp)(void); // fp points to a function that has type F
F *e(void) { /* ... */ } // e returns a pointer to a function
F *((e))(void) { /* ... */ } // same: parentheses irrelevant
int (*fp)(void); // fp points to a function that has type F
</small>
<p><small><a name="note142" href="#note142">142)</a> See ''future language directions'' (<a href="#6.11.7">6.11.7</a>).
</small>
<h4><a name="6.9.2" href="#6.9.2">6.9.2 External object definitions</a></h4>
</small>
<p><small><a name="note142" href="#note142">142)</a> See ''future language directions'' (<a href="#6.11.7">6.11.7</a>).
</small>
<h4><a name="6.9.2" href="#6.9.2">6.9.2 External object definitions</a></h4>
<p><!--para 1 -->
If the declaration of an identifier for an object has file scope and an initializer, the
declaration is an external definition for the identifier.
<p><!--para 1 -->
If the declaration of an identifier for an object has file scope and an initializer, the
declaration is an external definition for the identifier.
extern int i2; // refers to previous, whose linkage is internal
extern int i3; // refers to previous, whose linkage is external
extern int i4; // refers to previous, whose linkage is external
extern int i2; // refers to previous, whose linkage is internal
extern int i3; // refers to previous, whose linkage is external
extern int i4; // refers to previous, whose linkage is external
the array i still has incomplete type, the implicit initializer causes it to have one element, which is set to
zero on program startup.
<!--page 157 -->
<h3><a name="6.10" href="#6.10">6.10 Preprocessing directives</a></h3>
the array i still has incomplete type, the implicit initializer causes it to have one element, which is set to
zero on program startup.
<!--page 157 -->
<h3><a name="6.10" href="#6.10">6.10 Preprocessing directives</a></h3>
<p><!--para 2 -->
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the
following constraints: The first token in the sequence is a # preprocessing token that (at
<p><!--para 2 -->
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the
following constraints: The first token in the sequence is a # preprocessing token that (at
When in a group that is skipped (<a href="#6.10.1">6.10.1</a>), the directive syntax is relaxed to allow any
sequence of preprocessing tokens to occur between the directive name and the following
new-line character.
When in a group that is skipped (<a href="#6.10.1">6.10.1</a>), the directive syntax is relaxed to allow any
sequence of preprocessing tokens to occur between the directive name and the following
new-line character.
<p><!--para 5 -->
The only white-space characters that shall appear between preprocessing tokens within a
preprocessing directive (from just after the introducing # preprocessing token through
just before the terminating new-line character) are space and horizontal-tab (including
spaces that have replaced comments or possibly other white-space characters in
translation phase 3).
<p><!--para 5 -->
The only white-space characters that shall appear between preprocessing tokens within a
preprocessing directive (from just after the introducing # preprocessing token through
just before the terminating new-line character) are space and horizontal-tab (including
spaces that have replaced comments or possibly other white-space characters in
translation phase 3).
<p><!--para 6 -->
The implementation can process and skip sections of source files conditionally, include
other source files, and replace macros. These capabilities are called preprocessing,
<p><!--para 6 -->
The implementation can process and skip sections of source files conditionally, include
other source files, and replace macros. These capabilities are called preprocessing,
the sequence of preprocessing tokens on the second line is not a preprocessing directive, because it does not
begin with a # at the start of translation phase 4, even though it will do so after the macro EMPTY has been
replaced.
the sequence of preprocessing tokens on the second line is not a preprocessing directive, because it does not
begin with a # at the start of translation phase 4, even though it will do so after the macro EMPTY has been
replaced.
<p><small><a name="note143" href="#note143">143)</a> 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 <a href="#6.10.3.2">6.10.3.2</a>, for example).
</small>
<h4><a name="6.10.1" href="#6.10.1">6.10.1 Conditional inclusion</a></h4>
<p><small><a name="note143" href="#note143">143)</a> 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 <a href="#6.10.3.2">6.10.3.2</a>, for example).
</small>
<h4><a name="6.10.1" href="#6.10.1">6.10.1 Conditional inclusion</a></h4>
<p><!--para 1 -->
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
<p><!--para 1 -->
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
which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is
predefined or if it has been the subject of a #define preprocessing directive without an
intervening #undef directive with the same subject identifier), 0 if it is not.
which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is
predefined or if it has been the subject of a #define preprocessing directive without an
intervening #undef directive with the same subject identifier), 0 if it is not.
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 (<a href="#6.4">6.4</a>).
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 (<a href="#6.4">6.4</a>).
check whether the controlling constant expression evaluates to nonzero.
<p><!--para 4 -->
Prior to evaluation, macro invocations in the list of preprocessing tokens that will become
check whether the controlling constant expression evaluates to nonzero.
<p><!--para 4 -->
Prior to evaluation, macro invocations in the list of preprocessing tokens that will become
check whether the identifier is or is not currently defined as a macro name. Their
conditions are equivalent to #if defined identifier and #if !defined identifier
respectively.
check whether the identifier is or is not currently defined as a macro name. Their
conditions are equivalent to #if defined identifier and #if !defined identifier
respectively.
<p><b> Forward references</b>: macro replacement (<a href="#6.10.3">6.10.3</a>), source file inclusion (<a href="#6.10.2">6.10.2</a>), largest
integer types (<a href="#7.18.1.5">7.18.1.5</a>).
<p><b> Forward references</b>: macro replacement (<a href="#6.10.3">6.10.3</a>), source file inclusion (<a href="#6.10.2">6.10.2</a>), largest
integer types (<a href="#7.18.1.5">7.18.1.5</a>).
<p><small><a name="note144" href="#note144">144)</a> 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.
</small>
<p><small><a name="note144" href="#note144">144)</a> 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.
</small>
searches a sequence of implementation-defined places for a header identified uniquely by
the specified sequence between the < and > delimiters, and causes the replacement of that
directive by the entire contents of the header. How the places are specified or the header
searches a sequence of implementation-defined places for a header identified uniquely by
the specified sequence between the < and > delimiters, and causes the replacement of that
directive by the entire contents of the header. How the places are specified or the header
causes the replacement of that directive by the entire contents of the source file identified
by the specified sequence between the " delimiters. The named source file is searched
for in an implementation-defined manner. If this search is not supported, or if the search
fails, the directive is reprocessed as if it read
<pre>
causes the replacement of that directive by the entire contents of the source file identified
by the specified sequence between the " delimiters. The named source file is searched
for in an implementation-defined manner. If this search is not supported, or if the search
fails, the directive is reprocessed as if it read
<pre>
with the identical contained sequence (including > characters, if any) from the original
directive.
<p><!--para 4 -->
A preprocessing directive of the form
<pre>
with the identical contained sequence (including > characters, if any) from the original
directive.
<p><!--para 4 -->
A preprocessing directive of the form
<pre>
(that does not match one of the two previous forms) is permitted. The preprocessing
tokens after include in the directive are processed just as in normal text. (Each
identifier currently defined as a macro name is replaced by its replacement list of
(that does not match one of the two previous forms) is permitted. The preprocessing
tokens after include in the directive are processed just as in normal text. (Each
identifier currently defined as a macro name is replaced by its replacement list of
EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following:
<pre>
#include <a href="#7.19"><stdio.h></a>
EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following:
<pre>
#include <a href="#7.19"><stdio.h></a>
<p><small><a name="note148" href="#note148">148)</a> Note that adjacent string literals are not concatenated into a single string literal (see the translation
phases in <a href="#5.1.1.2">5.1.1.2</a>); thus, an expansion that results in two string literals is an invalid directive.
</small>
<h4><a name="6.10.3" href="#6.10.3">6.10.3 Macro replacement</a></h4>
<p><small><a name="note148" href="#note148">148)</a> Note that adjacent string literals are not concatenated into a single string literal (see the translation
phases in <a href="#5.1.1.2">5.1.1.2</a>); thus, an expansion that results in two string literals is an invalid directive.
</small>
<h4><a name="6.10.3" href="#6.10.3">6.10.3 Macro replacement</a></h4>
<p><!--para 1 -->
Two replacement lists are identical if and only if the preprocessing tokens in both have
the same number, ordering, spelling, and white-space separation, where all white-space
<p><!--para 1 -->
Two replacement lists are identical if and only if the preprocessing tokens in both have
the same number, ordering, spelling, and white-space separation, where all white-space
<p><!--para 7 -->
The identifier immediately following the define is called the macro name. There is one
name space for macro names. Any white-space characters preceding or following the
<p><!--para 7 -->
The identifier immediately following the define is called the macro name. There is one
name space for macro names. Any white-space characters preceding or following the
defines an object-like macro that causes each subsequent instance of the macro name<sup><a href="#note149"><b>149)</b></a></sup>
to be replaced by the replacement list of preprocessing tokens that constitute the
remainder of the directive. The replacement list is then rescanned for more macro names
defines an object-like macro that causes each subsequent instance of the macro name<sup><a href="#note149"><b>149)</b></a></sup>
to be replaced by the replacement list of preprocessing tokens that constitute the
remainder of the directive. The replacement list is then rescanned for more macro names
<pre>
# define identifier lparen identifier-list<sub>opt</sub> ) replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
<pre>
# define identifier lparen identifier-list<sub>opt</sub> ) replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
defines a function-like macro with parameters, whose use is similar syntactically to a
function call. The parameters are specified by the optional list of identifiers, whose scope
extends from their declaration in the identifier list until the new-line character that
defines a function-like macro with parameters, whose use is similar syntactically to a
function call. The parameters are specified by the optional list of identifiers, whose scope
extends from their declaration in the identifier list until the new-line character that
merger, the number of arguments is one more than the number of parameters in the macro
definition (excluding the ...).
merger, the number of arguments is one more than the number of parameters in the macro
definition (excluding the ...).
<p><small><a name="note149" href="#note149">149)</a> Since, by macro-replacement time, all character constants and string literals are preprocessing tokens,
not sequences possibly containing identifier-like subsequences (see <a href="#5.1.1.2">5.1.1.2</a>, translation phases), they
are never scanned for macro names or parameters.
<p><small><a name="note149" href="#note149">149)</a> Since, by macro-replacement time, all character constants and string literals are preprocessing tokens,
not sequences possibly containing identifier-like subsequences (see <a href="#5.1.1.2">5.1.1.2</a>, translation phases), they
are never scanned for macro names or parameters.
<p><!--para 1 -->
Each # preprocessing token in the replacement list for a function-like macro shall be
followed by a parameter as the next preprocessing token in the replacement list.
<p><!--para 1 -->
Each # preprocessing token in the replacement list for a function-like macro shall be
followed by a parameter as the next preprocessing token in the replacement list.
<p><!--para 2 -->
If, in the replacement list, a parameter is immediately preceded by a # preprocessing
token, both are replaced by a single character string literal preprocessing token that
<p><!--para 2 -->
If, in the replacement list, a parameter is immediately preceded by a # preprocessing
token, both are replaced by a single character string literal preprocessing token that
<p><!--para 1 -->
A ## preprocessing token shall not occur at the beginning or at the end of a replacement
list for either form of macro definition.
<p><!--para 1 -->
A ## preprocessing token shall not occur at the beginning or at the end of a replacement
list for either form of macro definition.
<p><!--para 2 -->
If, in the replacement list of a function-like macro, a parameter is immediately preceded
or followed by a ## preprocessing token, the parameter is replaced by the corresponding
<p><!--para 2 -->
If, in the replacement list of a function-like macro, a parameter is immediately preceded
or followed by a ## preprocessing token, the parameter is replaced by the corresponding
#define in_between(a) mkstr(a)
#define join(c, d) in_between(c hash_hash d)
char p[] = join(x, y); // equivalent to
#define in_between(a) mkstr(a)
#define join(c, d) in_between(c hash_hash d)
char p[] = join(x, y); // equivalent to
The expansion produces, at various stages:
<pre>
join(x, y)
in_between(x hash_hash y)
in_between(x ## y)
mkstr(x ## y)
The expansion produces, at various stages:
<pre>
join(x, y)
in_between(x hash_hash y)
in_between(x ## y)
mkstr(x ## y)
In other words, expanding hash_hash produces a new token, consisting of two adjacent sharp signs, but
this new token is not the ## operator.
<!--page 167 -->
In other words, expanding hash_hash produces a new token, consisting of two adjacent sharp signs, but
this new token is not the ## operator.
<!--page 167 -->
<p><small><a name="note151" href="#note151">151)</a> Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
exist only within translation phase 4.
</small>
<p><small><a name="note151" href="#note151">151)</a> Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
exist only within translation phase 4.
</small>
causes the specified identifier no longer to be defined as a macro name. It is ignored if
the specified identifier is not currently defined as a macro name.
<p><!--para 3 -->
EXAMPLE 1 The simplest use of this facility is to define a ''manifest constant'', as in
<pre>
#define TABSIZE 100
causes the specified identifier no longer to be defined as a macro name. It is ignored if
the specified identifier is not currently defined as a macro name.
<p><!--para 3 -->
EXAMPLE 1 The simplest use of this facility is to define a ''manifest constant'', as in
<pre>
#define TABSIZE 100
arguments a second time (including side effects) and generating more code than a function if invoked
several times. It also cannot have its address taken, as it has none.
<pre>
arguments a second time (including side effects) and generating more code than a function if invoked
several times. It also cannot have its address taken, as it has none.
<pre>
g(x+(3,4)-w) | h 5) & m
(f)^m(m);
p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };
g(x+(3,4)-w) | h 5) & m
(f)^m(m);
p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };
results in
<pre>
f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1);
f(2 * (2+(3,4)-0,1)) | f(2 * (~ 5)) & f(2 * (0,1))^m(0,1);
int i[] = { 1, 23, 4, 5, };
results in
<pre>
f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1);
f(2 * (2+(3,4)-0,1)) | f(2 * (~ 5)) & f(2 * (0,1))^m(0,1);
int i[] = { 1, 23, 4, 5, };
or, after concatenation of the character string literals,
<pre>
printf("x1= %d, x2= %s", x1, x2);
or, after concatenation of the character string literals,
<pre>
printf("x1= %d, x2= %s", x1, x2);
<pre>
#define t(x,y,z) x ## y ## z
int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,),
<pre>
#define t(x,y,z) x ## y ## z
int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,),
- t(10,,), t(,11,), t(,,12), t(,,) };</pre>
+ t(10,,), t(,11,), t(,,12), t(,,) };
+</pre>
results in
<pre>
int j[] = { 123, 45, 67, 89,
results in
<pre>
int j[] = { 123, 45, 67, 89,
#define FUNC_LIKE(a) ( a )
#define FUNC_LIKE( a )( /* note the white space */ \
a /* other stuff on this line
#define FUNC_LIKE(a) ( a )
#define FUNC_LIKE( a )( /* note the white space */ \
a /* other stuff on this line
But the following redefinitions are invalid:
<pre>
#define OBJ_LIKE (0) // different token sequence
#define OBJ_LIKE (1 - 1) // different white space
#define FUNC_LIKE(b) ( a ) // different parameter usage
But the following redefinitions are invalid:
<pre>
#define OBJ_LIKE (0) // different token sequence
#define OBJ_LIKE (1 - 1) // different white space
#define FUNC_LIKE(b) ( a ) // different parameter usage
- report(x>y, "x is %d but y is %d", x, y);</pre>
+ report(x>y, "x is %d but y is %d", x, y);
+</pre>
results in
<pre>
fprintf(stderr, "Flag" );
fprintf(stderr, "X = %d\n", x );
puts( "The first, second, and third items." );
((x>y)?puts("x>y"):
results in
<pre>
fprintf(stderr, "Flag" );
fprintf(stderr, "X = %d\n", x );
puts( "The first, second, and third items." );
((x>y)?puts("x>y"):
<p><!--para 2 -->
The line number of the current source line is one greater than the number of new-line
characters read or introduced in translation phase 1 (<a href="#5.1.1.2">5.1.1.2</a>) while processing the source
<p><!--para 2 -->
The line number of the current source line is one greater than the number of new-line
characters read or introduced in translation phase 1 (<a href="#5.1.1.2">5.1.1.2</a>) while processing the source
causes the implementation to behave as if the following sequence of source lines begins
with a source line that has a line number as specified by the digit sequence (interpreted as
a decimal integer). The digit sequence shall not specify zero, nor a number greater than
causes the implementation to behave as if the following sequence of source lines begins
with a source line that has a line number as specified by the digit sequence (interpreted as
a decimal integer). The digit sequence shall not specify zero, nor a number greater than
sets the presumed line number similarly and changes the presumed name of the source
file to be the contents of the character string literal.
<p><!--para 5 -->
A preprocessing directive of the form
<pre>
sets the presumed line number similarly and changes the presumed name of the source
file to be the contents of the character string literal.
<p><!--para 5 -->
A preprocessing directive of the form
<pre>
(that does not match one of the two previous forms) is permitted. The preprocessing
tokens after line on the directive are processed just as in normal text (each identifier
currently defined as a macro name is replaced by its replacement list of preprocessing
(that does not match one of the two previous forms) is permitted. The preprocessing
tokens after line on the directive are processed just as in normal text (each identifier
currently defined as a macro name is replaced by its replacement list of preprocessing
causes the implementation to produce a diagnostic message that includes the specified
sequence of preprocessing tokens.
<h4><a name="6.10.6" href="#6.10.6">6.10.6 Pragma directive</a></h4>
causes the implementation to produce a diagnostic message that includes the specified
sequence of preprocessing tokens.
<h4><a name="6.10.6" href="#6.10.6">6.10.6 Pragma directive</a></h4>
where the preprocessing token STDC does not immediately follow pragma in the
directive (prior to any macro replacement)<sup><a href="#note152"><b>152)</b></a></sup> causes the implementation to behave in an
implementation-defined manner. The behavior might cause translation to fail or cause the
where the preprocessing token STDC does not immediately follow pragma in the
directive (prior to any macro replacement)<sup><a href="#note152"><b>152)</b></a></sup> causes the implementation to behave in an
implementation-defined manner. The behavior might cause translation to fail or cause the
<p><b> Forward references</b>: the FP_CONTRACT pragma (<a href="#7.12.2">7.12.2</a>), the FENV_ACCESS pragma
(<a href="#7.6.1">7.6.1</a>), the CX_LIMITED_RANGE pragma (<a href="#7.3.4">7.3.4</a>).
<p><b> Forward references</b>: the FP_CONTRACT pragma (<a href="#7.12.2">7.12.2</a>), the FENV_ACCESS pragma
(<a href="#7.6.1">7.6.1</a>), the CX_LIMITED_RANGE pragma (<a href="#7.3.4">7.3.4</a>).
<p><small><a name="note152" href="#note152">152)</a> 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
<p><small><a name="note152" href="#note152">152)</a> 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
<p><small><a name="note154" href="#note154">154)</a> See ''future language directions'' (<a href="#6.11.9">6.11.9</a>).
</small>
<p><small><a name="note155" href="#note155">155)</a> The presumed source file name and line number can be changed by the #line directive.
<p><small><a name="note154" href="#note154">154)</a> See ''future language directions'' (<a href="#6.11.9">6.11.9</a>).
</small>
<p><small><a name="note155" href="#note155">155)</a> The presumed source file name and line number can be changed by the #line directive.
is processed as follows: The string literal is destringized by deleting the L prefix, if
present, deleting the leading and trailing double-quotes, replacing each escape sequence
\" by a double-quote, and replacing each escape sequence \\ by a single backslash. The
is processed as follows: The string literal is destringized by deleting the L prefix, if
present, deleting the leading and trailing double-quotes, replacing each escape sequence
\" by a double-quote, and replacing each escape sequence \\ by a single backslash. The
The latter form is processed in the same way whether it appears literally as shown, or results from macro
replacement, as in:
<!--page 175 -->
<pre>
#define LISTING(x) PRAGMA(listing on #x)
#define PRAGMA(x) _Pragma(#x)
The latter form is processed in the same way whether it appears literally as shown, or results from macro
replacement, as in:
<!--page 175 -->
<pre>
#define LISTING(x) PRAGMA(listing on #x)
#define PRAGMA(x) _Pragma(#x)
<p><small><a name="note157" href="#note157">157)</a> The functions that make use of the decimal-point character are the numeric conversion functions
(<a href="#7.20.1">7.20.1</a>, <a href="#7.24.4.1">7.24.4.1</a>) and the formatted input/output functions (<a href="#7.19.6">7.19.6</a>, <a href="#7.24.2">7.24.2</a>).
</small>
<p><small><a name="note157" href="#note157">157)</a> The functions that make use of the decimal-point character are the numeric conversion functions
(<a href="#7.20.1">7.20.1</a>, <a href="#7.24.4.1">7.24.4.1</a>) and the formatted input/output functions (<a href="#7.19.6">7.19.6</a>, <a href="#7.24.2">7.24.2</a>).
</small>
<pre>
<a href="#7.2"><assert.h></a> <a href="#7.8"><inttypes.h></a> <a href="#7.14"><signal.h></a> <a href="#7.20"><stdlib.h></a>
<a href="#7.3"><complex.h></a> <a href="#7.9"><iso646.h></a> <a href="#7.15"><stdarg.h></a> <a href="#7.21"><string.h></a>
<a href="#7.4"><ctype.h></a> <a href="#7.10"><limits.h></a> <a href="#7.16"><stdbool.h></a> <a href="#7.22"><tgmath.h></a>
<a href="#7.5"><errno.h></a> <a href="#7.11"><locale.h></a> <a href="#7.17"><stddef.h></a> <a href="#7.23"><time.h></a>
<a href="#7.6"><fenv.h></a> <a href="#7.12"><math.h></a> <a href="#7.18"><stdint.h></a> <a href="#7.24"><wchar.h></a>
<pre>
<a href="#7.2"><assert.h></a> <a href="#7.8"><inttypes.h></a> <a href="#7.14"><signal.h></a> <a href="#7.20"><stdlib.h></a>
<a href="#7.3"><complex.h></a> <a href="#7.9"><iso646.h></a> <a href="#7.15"><stdarg.h></a> <a href="#7.21"><string.h></a>
<a href="#7.4"><ctype.h></a> <a href="#7.10"><limits.h></a> <a href="#7.16"><stdbool.h></a> <a href="#7.22"><tgmath.h></a>
<a href="#7.5"><errno.h></a> <a href="#7.11"><locale.h></a> <a href="#7.17"><stddef.h></a> <a href="#7.23"><time.h></a>
<a href="#7.6"><fenv.h></a> <a href="#7.12"><math.h></a> <a href="#7.18"><stdint.h></a> <a href="#7.24"><wchar.h></a>
If a file with the same name as one of the above < and > delimited sequences, not
provided as part of the implementation, is placed in any of the standard places that are
searched for included source files, the behavior is undefined.
If a file with the same name as one of the above < and > delimited sequences, not
provided as part of the implementation, is placed in any of the standard places that are
searched for included source files, the behavior is undefined.
<p><small><a name="note159" href="#note159">159)</a> A header is not necessarily a source file, nor are the < and > delimited sequences in header names
necessarily valid source file names.
</small>
<p><small><a name="note159" href="#note159">159)</a> A header is not necessarily a source file, nor are the < and > delimited sequences in header names
necessarily valid source file names.
</small>
If the program removes (with #undef) any macro definition of an identifier in the first
group listed above, the behavior is undefined.
If the program removes (with #undef) any macro definition of an identifier in the first
group listed above, the behavior is undefined.
<p><small><a name="note160" href="#note160">160)</a> The list of reserved identifiers with external linkage includes errno, math_errhandling,
setjmp, and va_end.
</small>
<p><small><a name="note160" href="#note160">160)</a> The list of reserved identifiers with external linkage includes errno, math_errhandling,
setjmp, and va_end.
</small>
<li> by use of its associated header (assuredly generating a true function reference)
<pre>
#include <a href="#7.20"><stdlib.h></a>
#undef atoi
const char *str;
/* ... */
<li> by use of its associated header (assuredly generating a true function reference)
<pre>
#include <a href="#7.20"><stdlib.h></a>
#undef atoi
const char *str;
/* ... */
<p><small><a name="note161" href="#note161">161)</a> This means that an implementation shall provide an actual function for each library function, even if it
also provides a macro for that function.
</small>
<p><small><a name="note161" href="#note161">161)</a> This means that an implementation shall provide an actual function for each library function, even if it
also provides a macro for that function.
</small>
for a compiler whose code generator will accept it.
In this manner, a user desiring to guarantee that a given library function such as abs will be a genuine
function may write
<pre>
for a compiler whose code generator will accept it.
In this manner, a user desiring to guarantee that a given library function such as abs will be a genuine
function may write
<pre>
whether the implementation's header provides a macro implementation of abs or a built-in
implementation. The prototype for the function, which precedes and is hidden by any macro
definition, is thereby revealed also.
whether the implementation's header provides a macro implementation of abs or a built-in
implementation. The prototype for the function, which precedes and is hidden by any macro
definition, is thereby revealed also.
<p><small><a name="note164" href="#note164">164)</a> Thus, a signal handler cannot, in general, call standard library functions.
</small>
<p><small><a name="note164" href="#note164">164)</a> Thus, a signal handler cannot, in general, call standard library functions.
</small>
which is not defined by <a href="#7.2"><assert.h></a>. If NDEBUG is defined as a macro name at the
point in the source file where <a href="#7.2"><assert.h></a> is included, the assert macro is defined
simply as
<pre>
which is not defined by <a href="#7.2"><assert.h></a>. If NDEBUG is defined as a macro name at the
point in the source file where <a href="#7.2"><assert.h></a> is included, the assert macro is defined
simply as
<pre>
The assert macro is redefined according to the current state of NDEBUG each time that
<a href="#7.2"><assert.h></a> is included.
<p><!--para 2 -->
The assert macro is redefined according to the current state of NDEBUG each time that
<a href="#7.2"><assert.h></a> is included.
<p><!--para 2 -->
<h4><a name="7.2.1" href="#7.2.1">7.2.1 Program diagnostics</a></h4>
<h5><a name="7.2.1.1" href="#7.2.1.1">7.2.1.1 The assert macro</a></h5>
<h4><a name="7.2.1" href="#7.2.1">7.2.1 Program diagnostics</a></h4>
<h5><a name="7.2.1.1" href="#7.2.1.1">7.2.1.1 The assert macro</a></h5>
<p><!--para 2 -->
The assert macro puts diagnostic tests into programs; it expands to a void expression.
When it is executed, if expression (which shall have a scalar type) is false (that is,
<p><!--para 2 -->
The assert macro puts diagnostic tests into programs; it expands to a void expression.
When it is executed, if expression (which shall have a scalar type) is false (that is,
the preprocessing macros __FILE__ and __LINE__ and of the identifier
__func__) on the standard error stream in an implementation-defined format.<sup><a href="#note165"><b>165)</b></a></sup> It
then calls the abort function.
the preprocessing macros __FILE__ and __LINE__ and of the identifier
__func__) on the standard error stream in an implementation-defined format.<sup><a href="#note165"><b>165)</b></a></sup> It
then calls the abort function.
<p><!--para 3 -->
The assert macro returns no value.
<p><b> Forward references</b>: the abort function (<a href="#7.20.4.1">7.20.4.1</a>).
<p><!--para 3 -->
The assert macro returns no value.
<p><b> Forward references</b>: the abort function (<a href="#7.20.4.1">7.20.4.1</a>).
<p><small><a name="note165" href="#note165">165)</a> The message written might be of the form:
Assertion failed: expression, function abc, file xyz, line nnn.
</small>
<p><small><a name="note165" href="#note165">165)</a> The message written might be of the form:
Assertion failed: expression, function abc, file xyz, line nnn.
</small>
expands to a constant expression of type const float _Complex, with the value of
the imaginary unit.<sup><a href="#note167"><b>167)</b></a></sup>
<p><!--para 3 -->
The macros
<pre>
expands to a constant expression of type const float _Complex, with the value of
the imaginary unit.<sup><a href="#note167"><b>167)</b></a></sup>
<p><!--para 3 -->
The macros
<pre>
are defined if and only if the implementation supports imaginary types;<sup><a href="#note168"><b>168)</b></a></sup> if defined,
they expand to _Imaginary and a constant expression of type const float
_Imaginary with the value of the imaginary unit.
<p><!--para 4 -->
The macro
<pre>
are defined if and only if the implementation supports imaginary types;<sup><a href="#note168"><b>168)</b></a></sup> if defined,
they expand to _Imaginary and a constant expression of type const float
_Imaginary with the value of the imaginary unit.
<p><!--para 4 -->
The macro
<pre>
expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not
defined, I shall expand to _Complex_I.
<p><!--para 5 -->
expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not
defined, I shall expand to _Complex_I.
<p><!--para 5 -->
<p><small><a name="note166" href="#note166">166)</a> See ''future library directions'' (<a href="#7.26.1">7.26.1</a>).
</small>
<p><small><a name="note167" href="#note167">167)</a> The imaginary unit is a number i such that i<sup>2</sup> = -1.
<p><small><a name="note166" href="#note166">166)</a> See ''future library directions'' (<a href="#7.26.1">7.26.1</a>).
</small>
<p><small><a name="note167" href="#note167">167)</a> The imaginary unit is a number i such that i<sup>2</sup> = -1.
so the cut maps to the positive imaginary axis.
<h4><a name="7.3.4" href="#7.3.4">7.3.4 The CX_LIMITED_RANGE pragma</a></h4>
so the cut maps to the positive imaginary axis.
<h4><a name="7.3.4" href="#7.3.4">7.3.4 The CX_LIMITED_RANGE pragma</a></h4>
<p><!--para 2 -->
The usual mathematical formulas for complex multiply, divide, and absolute value are
problematic because of their treatment of infinities and because of undue overflow and
<p><!--para 2 -->
The usual mathematical formulas for complex multiply, divide, and absolute value are
problematic because of their treatment of infinities and because of undue overflow and
compound statement. If this pragma is used in any other context, the behavior is
undefined. The default state for the pragma is ''off''.
compound statement. If this pragma is used in any other context, the behavior is
undefined. The default state for the pragma is ''off''.
<h4><a name="7.3.5" href="#7.3.5">7.3.5 Trigonometric functions</a></h4>
<h5><a name="7.3.5.1" href="#7.3.5.1">7.3.5.1 The cacos functions</a></h5>
<h4><a name="7.3.5" href="#7.3.5">7.3.5 Trigonometric functions</a></h4>
<h5><a name="7.3.5.1" href="#7.3.5.1">7.3.5.1 The cacos functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacos(double complex z);
float complex cacosf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacos(double complex z);
float complex cacosf(float complex z);
<p><!--para 2 -->
The cacos functions compute the complex arc cosine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<p><!--para 2 -->
The cacos functions compute the complex arc cosine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<p><!--para 3 -->
The cacos functions return the complex arc cosine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the
real axis.
<h5><a name="7.3.5.2" href="#7.3.5.2">7.3.5.2 The casin functions</a></h5>
<p><!--para 3 -->
The cacos functions return the complex arc cosine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the
real axis.
<h5><a name="7.3.5.2" href="#7.3.5.2">7.3.5.2 The casin functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casin(double complex z);
float complex casinf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casin(double complex z);
float complex casinf(float complex z);
<p><!--para 2 -->
The casin functions compute the complex arc sine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<p><!--para 2 -->
The casin functions compute the complex arc sine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<p><!--para 3 -->
The casin functions return the complex arc sine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
<p><!--para 3 -->
The casin functions return the complex arc sine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catan(double complex z);
float complex catanf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catan(double complex z);
float complex catanf(float complex z);
<p><!--para 2 -->
The catan functions compute the complex arc tangent of z, with branch cuts outside the
interval [-i, +i] along the imaginary axis.
<p><!--para 2 -->
The catan functions compute the complex arc tangent of z, with branch cuts outside the
interval [-i, +i] along the imaginary axis.
<p><!--para 3 -->
The catan functions return the complex arc tangent value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
along the real axis.
<h5><a name="7.3.5.4" href="#7.3.5.4">7.3.5.4 The ccos functions</a></h5>
<p><!--para 3 -->
The catan functions return the complex arc tangent value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
along the real axis.
<h5><a name="7.3.5.4" href="#7.3.5.4">7.3.5.4 The ccos functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccos(double complex z);
float complex ccosf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccos(double complex z);
float complex ccosf(float complex z);
<p><!--para 3 -->
The ccos functions return the complex cosine value.
<h5><a name="7.3.5.5" href="#7.3.5.5">7.3.5.5 The csin functions</a></h5>
<p><!--para 3 -->
The ccos functions return the complex cosine value.
<h5><a name="7.3.5.5" href="#7.3.5.5">7.3.5.5 The csin functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csin(double complex z);
float complex csinf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csin(double complex z);
float complex csinf(float complex z);
<p><!--para 3 -->
The csin functions return the complex sine value.
<!--page 186 -->
<h5><a name="7.3.5.6" href="#7.3.5.6">7.3.5.6 The ctan functions</a></h5>
<p><!--para 3 -->
The csin functions return the complex sine value.
<!--page 186 -->
<h5><a name="7.3.5.6" href="#7.3.5.6">7.3.5.6 The ctan functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctan(double complex z);
float complex ctanf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctan(double complex z);
float complex ctanf(float complex z);
<p><!--para 3 -->
The ctan functions return the complex tangent value.
<h4><a name="7.3.6" href="#7.3.6">7.3.6 Hyperbolic functions</a></h4>
<h5><a name="7.3.6.1" href="#7.3.6.1">7.3.6.1 The cacosh functions</a></h5>
<p><!--para 3 -->
The ctan functions return the complex tangent value.
<h4><a name="7.3.6" href="#7.3.6">7.3.6 Hyperbolic functions</a></h4>
<h5><a name="7.3.6.1" href="#7.3.6.1">7.3.6.1 The cacosh functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacosh(double complex z);
float complex cacoshf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacosh(double complex z);
float complex cacoshf(float complex z);
<p><!--para 2 -->
The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch
cut at values less than 1 along the real axis.
<p><!--para 2 -->
The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch
cut at values less than 1 along the real axis.
<p><!--para 3 -->
The cacosh functions return the complex arc hyperbolic cosine value, in the range of a
half-strip of non-negative values along the real axis and in the interval [-ipi , +ipi ] along
the imaginary axis.
<h5><a name="7.3.6.2" href="#7.3.6.2">7.3.6.2 The casinh functions</a></h5>
<p><!--para 3 -->
The cacosh functions return the complex arc hyperbolic cosine value, in the range of a
half-strip of non-negative values along the real axis and in the interval [-ipi , +ipi ] along
the imaginary axis.
<h5><a name="7.3.6.2" href="#7.3.6.2">7.3.6.2 The casinh functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casinh(double complex z);
float complex casinhf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casinh(double complex z);
float complex casinhf(float complex z);
<p><!--para 2 -->
The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts
outside the interval [-i, +i] along the imaginary axis.
<!--page 187 -->
<p><!--para 2 -->
The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts
outside the interval [-i, +i] along the imaginary axis.
<!--page 187 -->
<p><!--para 3 -->
The casinh functions return the complex arc hyperbolic sine value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<h5><a name="7.3.6.3" href="#7.3.6.3">7.3.6.3 The catanh functions</a></h5>
<p><!--para 3 -->
The casinh functions return the complex arc hyperbolic sine value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<h5><a name="7.3.6.3" href="#7.3.6.3">7.3.6.3 The catanh functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catanh(double complex z);
float complex catanhf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catanh(double complex z);
float complex catanhf(float complex z);
<p><!--para 2 -->
The catanh functions compute the complex arc hyperbolic tangent of z, with branch
cuts outside the interval [-1, +1] along the real axis.
<p><!--para 2 -->
The catanh functions compute the complex arc hyperbolic tangent of z, with branch
cuts outside the interval [-1, +1] along the real axis.
<p><!--para 3 -->
The catanh functions return the complex arc hyperbolic tangent value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<h5><a name="7.3.6.4" href="#7.3.6.4">7.3.6.4 The ccosh functions</a></h5>
<p><!--para 3 -->
The catanh functions return the complex arc hyperbolic tangent value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<h5><a name="7.3.6.4" href="#7.3.6.4">7.3.6.4 The ccosh functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccosh(double complex z);
float complex ccoshf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccosh(double complex z);
float complex ccoshf(float complex z);
<p><!--para 3 -->
The ccosh functions return the complex hyperbolic cosine value.
<h5><a name="7.3.6.5" href="#7.3.6.5">7.3.6.5 The csinh functions</a></h5>
<p><!--para 3 -->
The ccosh functions return the complex hyperbolic cosine value.
<h5><a name="7.3.6.5" href="#7.3.6.5">7.3.6.5 The csinh functions</a></h5>
<p><!--para 1 -->
<!--page 188 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csinh(double complex z);
float complex csinhf(float complex z);
<p><!--para 1 -->
<!--page 188 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csinh(double complex z);
float complex csinhf(float complex z);
<p><!--para 3 -->
The csinh functions return the complex hyperbolic sine value.
<h5><a name="7.3.6.6" href="#7.3.6.6">7.3.6.6 The ctanh functions</a></h5>
<p><!--para 3 -->
The csinh functions return the complex hyperbolic sine value.
<h5><a name="7.3.6.6" href="#7.3.6.6">7.3.6.6 The ctanh functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctanh(double complex z);
float complex ctanhf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctanh(double complex z);
float complex ctanhf(float complex z);
<p><!--para 3 -->
The ctanh functions return the complex hyperbolic tangent value.
<h4><a name="7.3.7" href="#7.3.7">7.3.7 Exponential and logarithmic functions</a></h4>
<h5><a name="7.3.7.1" href="#7.3.7.1">7.3.7.1 The cexp functions</a></h5>
<p><!--para 3 -->
The ctanh functions return the complex hyperbolic tangent value.
<h4><a name="7.3.7" href="#7.3.7">7.3.7 Exponential and logarithmic functions</a></h4>
<h5><a name="7.3.7.1" href="#7.3.7.1">7.3.7.1 The cexp functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cexp(double complex z);
float complex cexpf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cexp(double complex z);
float complex cexpf(float complex z);
<p><!--para 3 -->
The cexp functions return the complex base-e exponential value.
<h5><a name="7.3.7.2" href="#7.3.7.2">7.3.7.2 The clog functions</a></h5>
<p><!--para 3 -->
The cexp functions return the complex base-e exponential value.
<h5><a name="7.3.7.2" href="#7.3.7.2">7.3.7.2 The clog functions</a></h5>
<p><!--para 1 -->
<!--page 189 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex clog(double complex z);
float complex clogf(float complex z);
<p><!--para 1 -->
<!--page 189 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex clog(double complex z);
float complex clogf(float complex z);
<p><!--para 2 -->
The clog functions compute the complex natural (base-e) logarithm of z, with a branch
cut along the negative real axis.
<p><!--para 2 -->
The clog functions compute the complex natural (base-e) logarithm of z, with a branch
cut along the negative real axis.
<p><!--para 3 -->
The clog functions return the complex natural logarithm value, in the range of a strip
mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the
<p><!--para 3 -->
The clog functions return the complex natural logarithm value, in the range of a strip
mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the
<h4><a name="7.3.8" href="#7.3.8">7.3.8 Power and absolute-value functions</a></h4>
<h5><a name="7.3.8.1" href="#7.3.8.1">7.3.8.1 The cabs functions</a></h5>
<h4><a name="7.3.8" href="#7.3.8">7.3.8 Power and absolute-value functions</a></h4>
<h5><a name="7.3.8.1" href="#7.3.8.1">7.3.8.1 The cabs functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cabs(double complex z);
float cabsf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cabs(double complex z);
float cabsf(float complex z);
<p><!--para 3 -->
The cabs functions return the complex absolute value.
<h5><a name="7.3.8.2" href="#7.3.8.2">7.3.8.2 The cpow functions</a></h5>
<p><!--para 3 -->
The cabs functions return the complex absolute value.
<h5><a name="7.3.8.2" href="#7.3.8.2">7.3.8.2 The cpow functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cpow(double complex x, double complex y);
float complex cpowf(float complex x, float complex y);
long double complex cpowl(long double complex x,
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cpow(double complex x, double complex y);
float complex cpowf(float complex x, float complex y);
long double complex cpowl(long double complex x,
<p><!--para 2 -->
The cpow functions compute the complex power function xy , with a branch cut for the
first parameter along the negative real axis.
<p><!--para 2 -->
The cpow functions compute the complex power function xy , with a branch cut for the
first parameter along the negative real axis.
<p><!--para 3 -->
The cpow functions return the complex power function value.
<!--page 190 -->
<h5><a name="7.3.8.3" href="#7.3.8.3">7.3.8.3 The csqrt functions</a></h5>
<p><!--para 3 -->
The cpow functions return the complex power function value.
<!--page 190 -->
<h5><a name="7.3.8.3" href="#7.3.8.3">7.3.8.3 The csqrt functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csqrt(double complex z);
float complex csqrtf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csqrt(double complex z);
float complex csqrtf(float complex z);
<p><!--para 3 -->
The csqrt functions return the complex square root value, in the range of the right half-
plane (including the imaginary axis).
<p><!--para 3 -->
The csqrt functions return the complex square root value, in the range of the right half-
plane (including the imaginary axis).
<h4><a name="7.3.9" href="#7.3.9">7.3.9 Manipulation functions</a></h4>
<h5><a name="7.3.9.1" href="#7.3.9.1">7.3.9.1 The carg functions</a></h5>
<h4><a name="7.3.9" href="#7.3.9">7.3.9 Manipulation functions</a></h4>
<h5><a name="7.3.9.1" href="#7.3.9.1">7.3.9.1 The carg functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double carg(double complex z);
float cargf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double carg(double complex z);
float cargf(float complex z);
<p><!--para 2 -->
The carg functions compute the argument (also called phase angle) of z, with a branch
cut along the negative real axis.
<p><!--para 2 -->
The carg functions compute the argument (also called phase angle) of z, with a branch
cut along the negative real axis.
<p><!--para 3 -->
The carg functions return the value of the argument in the interval [-pi , +pi ].
<h5><a name="7.3.9.2" href="#7.3.9.2">7.3.9.2 The cimag functions</a></h5>
<p><!--para 3 -->
The carg functions return the value of the argument in the interval [-pi , +pi ].
<h5><a name="7.3.9.2" href="#7.3.9.2">7.3.9.2 The cimag functions</a></h5>
<p><!--para 1 -->
<!--page 191 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cimag(double complex z);
float cimagf(float complex z);
<p><!--para 1 -->
<!--page 191 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cimag(double complex z);
float cimagf(float complex z);
<p><small><a name="note170" href="#note170">170)</a> For a variable z of complex type, z == creal(z) + cimag(z)*I.
</small>
<h5><a name="7.3.9.3" href="#7.3.9.3">7.3.9.3 The conj functions</a></h5>
<p><small><a name="note170" href="#note170">170)</a> For a variable z of complex type, z == creal(z) + cimag(z)*I.
</small>
<h5><a name="7.3.9.3" href="#7.3.9.3">7.3.9.3 The conj functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex conj(double complex z);
float complex conjf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex conj(double complex z);
float complex conjf(float complex z);
<p><!--para 3 -->
The conj functions return the complex conjugate value.
<h5><a name="7.3.9.4" href="#7.3.9.4">7.3.9.4 The cproj functions</a></h5>
<p><!--para 3 -->
The conj functions return the complex conjugate value.
<h5><a name="7.3.9.4" href="#7.3.9.4">7.3.9.4 The cproj functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cproj(double complex z);
float complex cprojf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cproj(double complex z);
float complex cprojf(float complex z);
<p><!--para 2 -->
The cproj functions compute a projection of z onto the Riemann sphere: z projects to
z except that all complex infinities (even those with one infinite part and one NaN part)
project to positive infinity on the real axis. If z has an infinite part, then cproj(z) is
equivalent to
<pre>
<p><!--para 2 -->
The cproj functions compute a projection of z onto the Riemann sphere: z projects to
z except that all complex infinities (even those with one infinite part and one NaN part)
project to positive infinity on the real axis. If z has an infinite part, then cproj(z) is
equivalent to
<pre>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double creal(double complex z);
float crealf(float complex z);
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double creal(double complex z);
float crealf(float complex z);
<p><!--para 1 -->
The header <a href="#7.4"><ctype.h></a> declares several functions useful for classifying and mapping
characters.<sup><a href="#note172"><b>172)</b></a></sup> In all cases the argument is an int, the value of which shall be
<p><!--para 1 -->
The header <a href="#7.4"><ctype.h></a> declares several functions useful for classifying and mapping
characters.<sup><a href="#note172"><b>172)</b></a></sup> In all cases the argument is an int, the value of which shall be
characters.<sup><a href="#note173"><b>173)</b></a></sup> All letters and digits are printing characters.
<p><b> Forward references</b>: EOF (<a href="#7.19.1">7.19.1</a>), localization (<a href="#7.11">7.11</a>).
characters.<sup><a href="#note173"><b>173)</b></a></sup> All letters and digits are printing characters.
<p><b> Forward references</b>: EOF (<a href="#7.19.1">7.19.1</a>), localization (<a href="#7.11">7.11</a>).
<p><small><a name="note172" href="#note172">172)</a> See ''future library directions'' (<a href="#7.26.2">7.26.2</a>).
</small>
<p><small><a name="note173" href="#note173">173)</a> In an implementation that uses the seven-bit US ASCII character set, the printing characters are those
<p><small><a name="note172" href="#note172">172)</a> See ''future library directions'' (<a href="#7.26.2">7.26.2</a>).
</small>
<p><small><a name="note173" href="#note173">173)</a> In an implementation that uses the seven-bit US ASCII character set, the printing characters are those
argument c conforms to that in the description of the function.
<h5><a name="7.4.1.1" href="#7.4.1.1">7.4.1.1 The isalnum function</a></h5>
argument c conforms to that in the description of the function.
<h5><a name="7.4.1.1" href="#7.4.1.1">7.4.1.1 The isalnum function</a></h5>
<p><!--para 2 -->
The isalnum function tests for any character for which isalpha or isdigit is true.
<h5><a name="7.4.1.2" href="#7.4.1.2">7.4.1.2 The isalpha function</a></h5>
<p><!--para 2 -->
The isalnum function tests for any character for which isalpha or isdigit is true.
<h5><a name="7.4.1.2" href="#7.4.1.2">7.4.1.2 The isalpha function</a></h5>
<p><!--para 2 -->
The isalpha function tests for any character for which isupper or islower is true,
or any character that is one of a locale-specific set of alphabetic characters for which
<p><!--para 2 -->
The isalpha function tests for any character for which isupper or islower is true,
or any character that is one of a locale-specific set of alphabetic characters for which
none of iscntrl, isdigit, ispunct, or isspace is true.<sup><a href="#note174"><b>174)</b></a></sup> In the "C" locale,
isalpha returns true only for the characters for which isupper or islower is true.
none of iscntrl, isdigit, ispunct, or isspace is true.<sup><a href="#note174"><b>174)</b></a></sup> In the "C" locale,
isalpha returns true only for the characters for which isupper or islower is true.
<p><small><a name="note174" href="#note174">174)</a> The functions islower and isupper test true or false separately for each of these additional
characters; all four combinations are possible.
</small>
<h5><a name="7.4.1.3" href="#7.4.1.3">7.4.1.3 The isblank function</a></h5>
<p><small><a name="note174" href="#note174">174)</a> The functions islower and isupper test true or false separately for each of these additional
characters; all four combinations are possible.
</small>
<h5><a name="7.4.1.3" href="#7.4.1.3">7.4.1.3 The isblank function</a></h5>
<p><!--para 2 -->
The isblank function tests for any character that is a standard blank character or is one
of a locale-specific set of characters for which isspace is true and that is used to
<p><!--para 2 -->
The isblank function tests for any character that is a standard blank character or is one
of a locale-specific set of characters for which isspace is true and that is used to
for the standard blank characters.
<h5><a name="7.4.1.4" href="#7.4.1.4">7.4.1.4 The iscntrl function</a></h5>
for the standard blank characters.
<h5><a name="7.4.1.4" href="#7.4.1.4">7.4.1.4 The iscntrl function</a></h5>
<p><!--para 2 -->
The iscntrl function tests for any control character.
<h5><a name="7.4.1.5" href="#7.4.1.5">7.4.1.5 The isdigit function</a></h5>
<p><!--para 2 -->
The iscntrl function tests for any control character.
<h5><a name="7.4.1.5" href="#7.4.1.5">7.4.1.5 The isdigit function</a></h5>
<p><!--para 2 -->
The isdigit function tests for any decimal-digit character (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.4.1.6" href="#7.4.1.6">7.4.1.6 The isgraph function</a></h5>
<p><!--para 2 -->
The isdigit function tests for any decimal-digit character (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.4.1.6" href="#7.4.1.6">7.4.1.6 The isgraph function</a></h5>
<p><!--para 2 -->
The isgraph function tests for any printing character except space (' ').
<h5><a name="7.4.1.7" href="#7.4.1.7">7.4.1.7 The islower function</a></h5>
<p><!--para 2 -->
The isgraph function tests for any printing character except space (' ').
<h5><a name="7.4.1.7" href="#7.4.1.7">7.4.1.7 The islower function</a></h5>
<p><!--para 2 -->
The islower function tests for any character that is a lowercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
<p><!--para 2 -->
The islower function tests for any character that is a lowercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
letters (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.4.1.8" href="#7.4.1.8">7.4.1.8 The isprint function</a></h5>
letters (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.4.1.8" href="#7.4.1.8">7.4.1.8 The isprint function</a></h5>
<p><!--para 2 -->
The isprint function tests for any printing character including space (' ').
<h5><a name="7.4.1.9" href="#7.4.1.9">7.4.1.9 The ispunct function</a></h5>
<p><!--para 2 -->
The isprint function tests for any printing character including space (' ').
<h5><a name="7.4.1.9" href="#7.4.1.9">7.4.1.9 The ispunct function</a></h5>
<p><!--para 2 -->
The ispunct function tests for any printing character that is one of a locale-specific set
of punctuation characters for which neither isspace nor isalnum is true. In the "C"
<p><!--para 2 -->
The ispunct function tests for any printing character that is one of a locale-specific set
of punctuation characters for which neither isspace nor isalnum is true. In the "C"
<p><!--para 2 -->
The isspace function tests for any character that is a standard white-space character or
is one of a locale-specific set of characters for which isalnum is false. The standard
<p><!--para 2 -->
The isspace function tests for any character that is a standard white-space character or
is one of a locale-specific set of characters for which isalnum is false. The standard
"C" locale, isspace returns true only for the standard white-space characters.
<h5><a name="7.4.1.11" href="#7.4.1.11">7.4.1.11 The isupper function</a></h5>
"C" locale, isspace returns true only for the standard white-space characters.
<h5><a name="7.4.1.11" href="#7.4.1.11">7.4.1.11 The isupper function</a></h5>
<p><!--para 2 -->
The isupper function tests for any character that is an uppercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
<p><!--para 2 -->
The isupper function tests for any character that is an uppercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
letters (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.4.1.12" href="#7.4.1.12">7.4.1.12 The isxdigit function</a></h5>
letters (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.4.1.12" href="#7.4.1.12">7.4.1.12 The isxdigit function</a></h5>
<p><!--para 2 -->
The isxdigit function tests for any hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<h4><a name="7.4.2" href="#7.4.2">7.4.2 Character case mapping functions</a></h4>
<h5><a name="7.4.2.1" href="#7.4.2.1">7.4.2.1 The tolower function</a></h5>
<p><!--para 2 -->
The isxdigit function tests for any hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<h4><a name="7.4.2" href="#7.4.2">7.4.2 Character case mapping functions</a></h4>
<h5><a name="7.4.2.1" href="#7.4.2.1">7.4.2.1 The tolower function</a></h5>
<p><!--para 3 -->
If the argument is a character for which isupper is true and there are one or more
corresponding characters, as specified by the current locale, for which islower is true,
<p><!--para 3 -->
If the argument is a character for which isupper is true and there are one or more
corresponding characters, as specified by the current locale, for which islower is true,
<p><!--para 3 -->
If the argument is a character for which islower is true and there are one or more
corresponding characters, as specified by the current locale, for which isupper is true,
<p><!--para 3 -->
If the argument is a character for which islower is true and there are one or more
corresponding characters, as specified by the current locale, for which isupper is true,
which expand to integer constant expressions with type int, distinct positive values, and
which are suitable for use in #if preprocessing directives; and
<pre>
which expand to integer constant expressions with type int, distinct positive values, and
which are suitable for use in #if preprocessing directives; and
<pre>
which expands to a modifiable lvalue<sup><a href="#note175"><b>175)</b></a></sup> that has type int, the value of which is set to a
positive error number by several library functions. It is unspecified whether errno is a
macro or an identifier declared with external linkage. If a macro definition is suppressed
which expands to a modifiable lvalue<sup><a href="#note175"><b>175)</b></a></sup> that has type int, the value of which is set to a
positive error number by several library functions. It is unspecified whether errno is a
macro or an identifier declared with external linkage. If a macro definition is suppressed
<p><small><a name="note175" href="#note175">175)</a> 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()).
</small>
<p><small><a name="note175" href="#note175">175)</a> 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()).
</small>
<p><!--para 1 -->
The header <a href="#7.6"><fenv.h></a> declares two types and several macros and functions to provide
access to the floating-point environment. The floating-point environment refers
<p><!--para 1 -->
The header <a href="#7.6"><fenv.h></a> declares two types and several macros and functions to provide
access to the floating-point environment. The floating-point environment refers
represents the floating-point status flags collectively, including any status the
implementation associates with the flags.
represents the floating-point status flags collectively, including any status the
implementation associates with the flags.
is defined if and only if the implementation supports the floating-point exception by
means of the functions in 7.6.2.<sup><a href="#note181"><b>181)</b></a></sup> Additional implementation-defined floating-point
exceptions, with macro definitions beginning with FE_ and an uppercase letter, may also
is defined if and only if the implementation supports the floating-point exception by
means of the functions in 7.6.2.<sup><a href="#note181"><b>181)</b></a></sup> Additional implementation-defined floating-point
exceptions, with macro definitions beginning with FE_ and an uppercase letter, may also
is simply the bitwise OR of all floating-point exception macros defined by the
implementation. If no such macros are defined, FE_ALL_EXCEPT shall be defined as 0.
<p><!--para 7 -->
is simply the bitwise OR of all floating-point exception macros defined by the
implementation. If no such macros are defined, FE_ALL_EXCEPT shall be defined as 0.
<p><!--para 7 -->
is defined if and only if the implementation supports getting and setting the represented
rounding direction by means of the fegetround and fesetround functions.
Additional implementation-defined rounding directions, with macro definitions beginning
is defined if and only if the implementation supports getting and setting the represented
rounding direction by means of the fegetround and fesetround functions.
Additional implementation-defined rounding directions, with macro definitions beginning
represents the default floating-point environment -- the one installed at program startup
-- and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to
<a href="#7.6"><fenv.h></a> functions that manage the floating-point environment.
represents the default floating-point environment -- the one installed at program startup
-- and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to
<a href="#7.6"><fenv.h></a> functions that manage the floating-point environment.
FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may
also be specified by the implementation.
FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may
also be specified by the implementation.
<p><small><a name="note178" href="#note178">178)</a> 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.
<p><small><a name="note178" href="#note178">178)</a> 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.
<p><!--para 2 -->
The FENV_ACCESS pragma provides a means to inform the implementation when a
program might access the floating-point environment to test floating-point status flags or
<p><!--para 2 -->
The FENV_ACCESS pragma provides a means to inform the implementation when a
program might access the floating-point environment to test floating-point status flags or
If the function g might depend on status flags set as a side effect of the first x + 1, or if the second
x + 1 might depend on control modes set as a side effect of the call to function g, then the program shall
contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.<sup><a href="#note185"><b>185)</b></a></sup>
If the function g might depend on status flags set as a side effect of the first x + 1, or if the second
x + 1 might depend on control modes set as a side effect of the call to function g, then the program shall
contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.<sup><a href="#note185"><b>185)</b></a></sup>
<p><small><a name="note184" href="#note184">184)</a> 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
<p><small><a name="note184" href="#note184">184)</a> 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
<p><small><a name="note186" href="#note186">186)</a> 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-
<p><small><a name="note186" href="#note186">186)</a> 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-
<p><!--para 2 -->
The feclearexcept function attempts to clear the supported floating-point exceptions
represented by its argument.
<p><!--para 2 -->
The feclearexcept function attempts to clear the supported floating-point exceptions
represented by its argument.
<p><!--para 3 -->
The feclearexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value.
<p><!--para 3 -->
The feclearexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value.
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetexceptflag(fexcept_t *flagp,
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetexceptflag(fexcept_t *flagp,
<p><!--para 2 -->
The fegetexceptflag function attempts to store an implementation-defined
representation of the states of the floating-point status flags indicated by the argument
excepts in the object pointed to by the argument flagp.
<p><!--para 2 -->
The fegetexceptflag function attempts to store an implementation-defined
representation of the states of the floating-point status flags indicated by the argument
excepts in the object pointed to by the argument flagp.
<p><!--para 3 -->
The fegetexceptflag function returns zero if the representation was successfully
stored. Otherwise, it returns a nonzero value.
<h5><a name="7.6.2.3" href="#7.6.2.3">7.6.2.3 The feraiseexcept function</a></h5>
<p><!--para 3 -->
The fegetexceptflag function returns zero if the representation was successfully
stored. Otherwise, it returns a nonzero value.
<h5><a name="7.6.2.3" href="#7.6.2.3">7.6.2.3 The feraiseexcept function</a></h5>
<p><!--para 2 -->
The feraiseexcept function attempts to raise the supported floating-point exceptions
represented by its argument.<sup><a href="#note187"><b>187)</b></a></sup> The order in which these floating-point exceptions are
raised is unspecified, except as stated in <a href="#F.7.6">F.7.6</a>. Whether the feraiseexcept function
additionally raises the ''inexact'' floating-point exception whenever it raises the
''overflow'' or ''underflow'' floating-point exception is implementation-defined.
<p><!--para 2 -->
The feraiseexcept function attempts to raise the supported floating-point exceptions
represented by its argument.<sup><a href="#note187"><b>187)</b></a></sup> The order in which these floating-point exceptions are
raised is unspecified, except as stated in <a href="#F.7.6">F.7.6</a>. Whether the feraiseexcept function
additionally raises the ''inexact'' floating-point exception whenever it raises the
''overflow'' or ''underflow'' floating-point exception is implementation-defined.
<p><!--para 3 -->
The feraiseexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully raised. Otherwise, it returns a nonzero value.
<p><!--para 3 -->
The feraiseexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully raised. Otherwise, it returns a nonzero value.
<p><small><a name="note187" href="#note187">187)</a> 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 <a href="#F.7.6">F.7.6</a> is in the same spirit.
</small>
<h5><a name="7.6.2.4" href="#7.6.2.4">7.6.2.4 The fesetexceptflag function</a></h5>
<p><small><a name="note187" href="#note187">187)</a> 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 <a href="#F.7.6">F.7.6</a> is in the same spirit.
</small>
<h5><a name="7.6.2.4" href="#7.6.2.4">7.6.2.4 The fesetexceptflag function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetexceptflag(const fexcept_t *flagp,
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetexceptflag(const fexcept_t *flagp,
<p><!--para 2 -->
The fesetexceptflag function attempts to set the floating-point status flags
indicated by the argument excepts to the states stored in the object pointed to by
<p><!--para 2 -->
The fesetexceptflag function attempts to set the floating-point status flags
indicated by the argument excepts to the states stored in the object pointed to by
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.
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.
<p><!--para 3 -->
The fesetexceptflag function returns zero if the excepts argument is zero or if
all the specified flags were successfully set to the appropriate state. Otherwise, it returns
a nonzero value.
<h5><a name="7.6.2.5" href="#7.6.2.5">7.6.2.5 The fetestexcept function</a></h5>
<p><!--para 3 -->
The fesetexceptflag function returns zero if the excepts argument is zero or if
all the specified flags were successfully set to the appropriate state. Otherwise, it returns
a nonzero value.
<h5><a name="7.6.2.5" href="#7.6.2.5">7.6.2.5 The fetestexcept function</a></h5>
<p><!--para 2 -->
The fetestexcept function determines which of a specified subset of the floating-
point exception flags are currently set. The excepts argument specifies the floating-
point status flags to be queried.<sup><a href="#note188"><b>188)</b></a></sup>
<p><!--para 2 -->
The fetestexcept function determines which of a specified subset of the floating-
point exception flags are currently set. The excepts argument specifies the floating-
point status flags to be queried.<sup><a href="#note188"><b>188)</b></a></sup>
<p><!--para 3 -->
The fetestexcept function returns the value of the bitwise OR of the floating-point
exception macros corresponding to the currently set floating-point exceptions included in
<p><!--para 3 -->
The fetestexcept function returns the value of the bitwise OR of the floating-point
exception macros corresponding to the currently set floating-point exceptions included in
<p><!--para 3 -->
The fegetround function returns the value of the rounding direction macro
representing the current rounding direction or a negative value if there is no such
rounding direction macro or the current rounding direction is not determinable.
<h5><a name="7.6.3.2" href="#7.6.3.2">7.6.3.2 The fesetround function</a></h5>
<p><!--para 3 -->
The fegetround function returns the value of the rounding direction macro
representing the current rounding direction or a negative value if there is no such
rounding direction macro or the current rounding direction is not determinable.
<h5><a name="7.6.3.2" href="#7.6.3.2">7.6.3.2 The fesetround function</a></h5>
<p><!--para 2 -->
The fesetround function establishes the rounding direction represented by its
argument round. If the argument is not equal to the value of a rounding direction macro,
the rounding direction is not changed.
<p><!--para 2 -->
The fesetround function establishes the rounding direction represented by its
argument round. If the argument is not equal to the value of a rounding direction macro,
the rounding direction is not changed.
control modes -- as one entity.
<h5><a name="7.6.4.1" href="#7.6.4.1">7.6.4.1 The fegetenv function</a></h5>
control modes -- as one entity.
<h5><a name="7.6.4.1" href="#7.6.4.1">7.6.4.1 The fegetenv function</a></h5>
<p><!--para 2 -->
The fegetenv function attempts to store the current floating-point environment in the
object pointed to by envp.
<p><!--para 2 -->
The fegetenv function attempts to store the current floating-point environment in the
object pointed to by envp.
<p><!--para 3 -->
The fegetenv function returns zero if the environment was successfully stored.
Otherwise, it returns a nonzero value.
<h5><a name="7.6.4.2" href="#7.6.4.2">7.6.4.2 The feholdexcept function</a></h5>
<p><!--para 3 -->
The fegetenv function returns zero if the environment was successfully stored.
Otherwise, it returns a nonzero value.
<h5><a name="7.6.4.2" href="#7.6.4.2">7.6.4.2 The feholdexcept function</a></h5>
<p><!--para 2 -->
The feholdexcept function saves the current floating-point environment in the object
pointed to by envp, clears the floating-point status flags, and then installs a non-stop
(continue on floating-point exceptions) mode, if available, for all floating-point
exceptions.<sup><a href="#note189"><b>189)</b></a></sup>
<!--page 207 -->
<p><!--para 2 -->
The feholdexcept function saves the current floating-point environment in the object
pointed to by envp, clears the floating-point status flags, and then installs a non-stop
(continue on floating-point exceptions) mode, if available, for all floating-point
exceptions.<sup><a href="#note189"><b>189)</b></a></sup>
<!--page 207 -->
<p><!--para 3 -->
The feholdexcept function returns zero if and only if non-stop floating-point
exception handling was successfully installed.
<p><!--para 3 -->
The feholdexcept function returns zero if and only if non-stop floating-point
exception handling was successfully installed.
<p><small><a name="note189" href="#note189">189)</a> 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
<p><small><a name="note189" href="#note189">189)</a> 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
<p><!--para 2 -->
The fesetenv function attempts to establish the floating-point environment represented
by the object pointed to by envp. The argument envp shall point to an object set by a
call to fegetenv or feholdexcept, or equal a floating-point environment macro.
Note that fesetenv merely installs the state of the floating-point status flags
represented through its argument, and does not raise these floating-point exceptions.
<p><!--para 2 -->
The fesetenv function attempts to establish the floating-point environment represented
by the object pointed to by envp. The argument envp shall point to an object set by a
call to fegetenv or feholdexcept, or equal a floating-point environment macro.
Note that fesetenv merely installs the state of the floating-point status flags
represented through its argument, and does not raise these floating-point exceptions.
<p><!--para 3 -->
The fesetenv function returns zero if the environment was successfully established.
Otherwise, it returns a nonzero value.
<h5><a name="7.6.4.4" href="#7.6.4.4">7.6.4.4 The feupdateenv function</a></h5>
<p><!--para 3 -->
The fesetenv function returns zero if the environment was successfully established.
Otherwise, it returns a nonzero value.
<h5><a name="7.6.4.4" href="#7.6.4.4">7.6.4.4 The feupdateenv function</a></h5>
<p><!--para 2 -->
The feupdateenv function attempts to save the currently raised floating-point
exceptions in its automatic storage, install the floating-point environment represented by
the object pointed to by envp, and then raise the saved floating-point exceptions. The
argument envp shall point to an object set by a call to feholdexcept or fegetenv,
or equal a floating-point environment macro.
<p><!--para 2 -->
The feupdateenv function attempts to save the currently raised floating-point
exceptions in its automatic storage, install the floating-point environment represented by
the object pointed to by envp, and then raise the saved floating-point exceptions. The
argument envp shall point to an object set by a call to feholdexcept or fegetenv,
or equal a floating-point environment macro.
<p><!--para 3 -->
The feupdateenv function returns zero if all the actions were successfully carried out.
Otherwise, it returns a nonzero value.
<p><!--para 3 -->
The feupdateenv function returns zero if all the actions were successfully carried out.
Otherwise, it returns a nonzero value.
<p><!--para 1 -->
The header <a href="#7.7"><float.h></a> defines several macros that expand to various limits and
parameters of the standard floating-point types.
<p><!--para 1 -->
The header <a href="#7.7"><float.h></a> defines several macros that expand to various limits and
parameters of the standard floating-point types.
<p><!--para 1 -->
The header <a href="#7.8"><inttypes.h></a> includes the header <a href="#7.18"><stdint.h></a> and extends it with
additional facilities provided by hosted implementations.
<p><!--para 1 -->
The header <a href="#7.8"><inttypes.h></a> includes the header <a href="#7.18"><stdint.h></a> and extends it with
additional facilities provided by hosted implementations.
It declares functions for manipulating greatest-width integers and converting numeric
character strings to greatest-width integers, and it declares the type
<pre>
It declares functions for manipulating greatest-width integers and converting numeric
character strings to greatest-width integers, and it declares the type
<pre>
which is a structure type that is the type of the value returned by the imaxdiv function.
For each type declared in <a href="#7.18"><stdint.h></a>, it defines corresponding macros for conversion
specifiers for use with the formatted input/output functions.<sup><a href="#note190"><b>190)</b></a></sup>
<p><b> Forward references</b>: integer types <a href="#7.18"><stdint.h></a> (<a href="#7.18">7.18</a>), formatted input/output
functions (<a href="#7.19.6">7.19.6</a>), formatted wide character input/output functions (<a href="#7.24.2">7.24.2</a>).
which is a structure type that is the type of the value returned by the imaxdiv function.
For each type declared in <a href="#7.18"><stdint.h></a>, it defines corresponding macros for conversion
specifiers for use with the formatted input/output functions.<sup><a href="#note190"><b>190)</b></a></sup>
<p><b> Forward references</b>: integer types <a href="#7.18"><stdint.h></a> (<a href="#7.18">7.18</a>), formatted input/output
functions (<a href="#7.19.6">7.19.6</a>), formatted wide character input/output functions (<a href="#7.24.2">7.24.2</a>).
<pre>
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR
<pre>
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR
For each type that the implementation provides in <a href="#7.18"><stdint.h></a>, the corresponding
fprintf macros shall be defined and the corresponding fscanf macros shall be
defined unless the implementation does not have a suitable fscanf length modifier for
For each type that the implementation provides in <a href="#7.18"><stdint.h></a>, the corresponding
fprintf macros shall be defined and the corresponding fscanf macros shall be
defined unless the implementation does not have a suitable fscanf length modifier for
<p><small><a name="note191" href="#note191">191)</a> C++ implementations should define these macros only when __STDC_FORMAT_MACROS is defined
before <a href="#7.8"><inttypes.h></a> is included.
</small>
<p><small><a name="note191" href="#note191">191)</a> C++ implementations should define these macros only when __STDC_FORMAT_MACROS is defined
before <a href="#7.8"><inttypes.h></a> is included.
</small>
<h4><a name="7.8.2" href="#7.8.2">7.8.2 Functions for greatest-width integer types</a></h4>
<h5><a name="7.8.2.1" href="#7.8.2.1">7.8.2.1 The imaxabs function</a></h5>
<h4><a name="7.8.2" href="#7.8.2">7.8.2 Functions for greatest-width integer types</a></h4>
<h5><a name="7.8.2.1" href="#7.8.2.1">7.8.2.1 The imaxabs function</a></h5>
<p><!--para 2 -->
The imaxabs function computes the absolute value of an integer j. If the result cannot
be represented, the behavior is undefined.<sup><a href="#note193"><b>193)</b></a></sup>
<p><!--para 2 -->
The imaxabs function computes the absolute value of an integer j. If the result cannot
be represented, the behavior is undefined.<sup><a href="#note193"><b>193)</b></a></sup>
<p><small><a name="note193" href="#note193">193)</a> The absolute value of the most negative number cannot be represented in two's complement.
</small>
<h5><a name="7.8.2.2" href="#7.8.2.2">7.8.2.2 The imaxdiv function</a></h5>
<p><small><a name="note193" href="#note193">193)</a> The absolute value of the most negative number cannot be represented in two's complement.
</small>
<h5><a name="7.8.2.2" href="#7.8.2.2">7.8.2.2 The imaxdiv function</a></h5>
<p><!--para 3 -->
The imaxdiv function returns a structure of type imaxdiv_t comprising both the
quotient and the remainder. The structure shall contain (in either order) the members
<p><!--para 3 -->
The imaxdiv function returns a structure of type imaxdiv_t comprising both the
quotient and the remainder. The structure shall contain (in either order) the members
either part of the result cannot be represented, the behavior is undefined.
<h5><a name="7.8.2.3" href="#7.8.2.3">7.8.2.3 The strtoimax and strtoumax functions</a></h5>
either part of the result cannot be represented, the behavior is undefined.
<h5><a name="7.8.2.3" href="#7.8.2.3">7.8.2.3 The strtoimax and strtoumax functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
intmax_t strtoimax(const char * restrict nptr,
char ** restrict endptr, int base);
uintmax_t strtoumax(const char * restrict nptr,
<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
intmax_t strtoimax(const char * restrict nptr,
char ** restrict endptr, int base);
uintmax_t strtoumax(const char * restrict nptr,
<p><!--para 2 -->
The strtoimax and strtoumax functions are equivalent to the strtol, strtoll,
strtoul, and strtoull functions, except that the initial portion of the string is
converted to intmax_t and uintmax_t representation, respectively.
<p><!--para 2 -->
The strtoimax and strtoumax functions are equivalent to the strtol, strtoll,
strtoul, and strtoull functions, except that the initial portion of the string is
converted to intmax_t and uintmax_t representation, respectively.
<p><!--para 3 -->
The strtoimax and strtoumax functions return the converted value, if any. If no
conversion could be performed, zero is returned. If the correct value is outside the range
<p><!--para 3 -->
The strtoimax and strtoumax functions return the converted value, if any. If no
conversion could be performed, zero is returned. If the correct value is outside the range
intmax_t wcstoimax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
uintmax_t wcstoumax(const wchar_t * restrict nptr,
intmax_t wcstoimax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
uintmax_t wcstoumax(const wchar_t * restrict nptr,
<p><!--para 2 -->
The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll,
wcstoul, and wcstoull functions except that the initial portion of the wide string is
converted to intmax_t and uintmax_t representation, respectively.
<p><!--para 2 -->
The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll,
wcstoul, and wcstoull functions except that the initial portion of the wide string is
converted to intmax_t and uintmax_t representation, respectively.
<p><!--para 3 -->
The wcstoimax function returns the converted value, if any. If no conversion could be
performed, zero is returned. If the correct value is outside the range of representable
<p><!--para 3 -->
The wcstoimax function returns the converted value, if any. If no conversion could be
performed, zero is returned. If the correct value is outside the range of representable
<p><!--para 1 -->
The header <a href="#7.9"><iso646.h></a> defines the following eleven macros (on the left) that expand
to the corresponding tokens (on the right):
<p><!--para 1 -->
The header <a href="#7.9"><iso646.h></a> defines the following eleven macros (on the left) that expand
to the corresponding tokens (on the right):
<p><!--para 1 -->
The header <a href="#7.10"><limits.h></a> defines several macros that expand to various limits and
parameters of the standard integer types.
<p><!--para 1 -->
The header <a href="#7.10"><limits.h></a> defines several macros that expand to various limits and
parameters of the standard integer types.
<p><!--para 1 -->
The header <a href="#7.11"><locale.h></a> declares two functions, one type, and defines several macros.
<p><!--para 2 -->
The type is
<pre>
<p><!--para 1 -->
The header <a href="#7.11"><locale.h></a> declares two functions, one type, and defines several macros.
<p><!--para 2 -->
The type is
<pre>
which contains members related to the formatting of numeric values. The structure shall
contain at least the following members, in any order. The semantics of the members and
their normal ranges are explained in <a href="#7.11.2.1">7.11.2.1</a>. In the "C" locale, the members shall have
the values specified in the comments.
<!--page 217 -->
which contains members related to the formatting of numeric values. The structure shall
contain at least the following members, in any order. The semantics of the members and
their normal ranges are explained in <a href="#7.11.2.1">7.11.2.1</a>. In the "C" locale, the members shall have
the values specified in the comments.
<!--page 217 -->
char int_p_sep_by_space; // CHAR_MAX
char int_n_sep_by_space; // CHAR_MAX
char int_p_sign_posn; // CHAR_MAX
char int_p_sep_by_space; // CHAR_MAX
char int_n_sep_by_space; // CHAR_MAX
char int_p_sign_posn; // CHAR_MAX
which expand to integer constant expressions with distinct values, suitable for use as the
first argument to the setlocale function.<sup><a href="#note194"><b>194)</b></a></sup> Additional macro definitions, beginning
with the characters LC_ and an uppercase letter,<sup><a href="#note195"><b>195)</b></a></sup> may also be specified by the
implementation.
which expand to integer constant expressions with distinct values, suitable for use as the
first argument to the setlocale function.<sup><a href="#note194"><b>194)</b></a></sup> Additional macro definitions, beginning
with the characters LC_ and an uppercase letter,<sup><a href="#note195"><b>195)</b></a></sup> may also be specified by the
implementation.
<p><small><a name="note194" href="#note194">194)</a> ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C.
</small>
<p><small><a name="note195" href="#note195">195)</a> See ''future library directions'' (<a href="#7.26.5">7.26.5</a>).
<p><small><a name="note194" href="#note194">194)</a> ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C.
</small>
<p><small><a name="note195" href="#note195">195)</a> See ''future library directions'' (<a href="#7.26.5">7.26.5</a>).
<h4><a name="7.11.1" href="#7.11.1">7.11.1 Locale control</a></h4>
<h5><a name="7.11.1.1" href="#7.11.1.1">7.11.1.1 The setlocale function</a></h5>
<h4><a name="7.11.1" href="#7.11.1">7.11.1 Locale control</a></h4>
<h5><a name="7.11.1.1" href="#7.11.1.1">7.11.1.1 The setlocale function</a></h5>
<p><!--para 2 -->
The setlocale function selects the appropriate portion of the program's locale as
specified by the category and locale arguments. The setlocale function may be
<p><!--para 2 -->
The setlocale function selects the appropriate portion of the program's locale as
specified by the category and locale arguments. The setlocale function may be
<p><!--para 6 -->
If a pointer to a string is given for locale and the selection can be honored, the
setlocale function returns a pointer to the string associated with the specified
<p><!--para 6 -->
If a pointer to a string is given for locale and the selection can be honored, the
setlocale function returns a pointer to the string associated with the specified
(<a href="#7.20.8">7.20.8</a>), numeric conversion functions (<a href="#7.20.1">7.20.1</a>), the strcoll function (<a href="#7.21.4.3">7.21.4.3</a>), the
strftime function (<a href="#7.23.3.5">7.23.3.5</a>), the strxfrm function (<a href="#7.21.4.5">7.21.4.5</a>).
(<a href="#7.20.8">7.20.8</a>), numeric conversion functions (<a href="#7.20.1">7.20.1</a>), the strcoll function (<a href="#7.21.4.3">7.21.4.3</a>), the
strftime function (<a href="#7.23.3.5">7.23.3.5</a>), the strxfrm function (<a href="#7.21.4.5">7.21.4.5</a>).
<h4><a name="7.11.2" href="#7.11.2">7.11.2 Numeric formatting convention inquiry</a></h4>
<h5><a name="7.11.2.1" href="#7.11.2.1">7.11.2.1 The localeconv function</a></h5>
<h4><a name="7.11.2" href="#7.11.2">7.11.2 Numeric formatting convention inquiry</a></h4>
<h5><a name="7.11.2.1" href="#7.11.2.1">7.11.2.1 The localeconv function</a></h5>
<p><!--para 2 -->
The localeconv function sets the components of an object with type struct lconv
with values appropriate for the formatting of numeric quantities (monetary and otherwise)
<p><!--para 2 -->
The localeconv function sets the components of an object with type struct lconv
with values appropriate for the formatting of numeric quantities (monetary and otherwise)
<p><!--para 8 -->
The localeconv function returns a pointer to the filled-in object. The structure
pointed to by the return value shall not be modified by the program, but may be
<p><!--para 8 -->
The localeconv function returns a pointer to the filled-in object. The structure
pointed to by the return value shall not be modified by the program, but may be
1 +$1.25 +$ <a href="#1.25">1.25</a> + $1.25
2 $1.25+ $ <a href="#1.25">1.25</a>+ $1.25 +
3 +$1.25 +$ <a href="#1.25">1.25</a> + $1.25
1 +$1.25 +$ <a href="#1.25">1.25</a> + $1.25
2 $1.25+ $ <a href="#1.25">1.25</a>+ $1.25 +
3 +$1.25 +$ <a href="#1.25">1.25</a> + $1.25
<p><!--para 1 -->
The header <a href="#7.12"><math.h></a> declares two types and many mathematical functions and defines
several macros. Most synopses specify a family of functions consisting of a principal
<p><!--para 1 -->
The header <a href="#7.12"><math.h></a> declares two types and many mathematical functions and defines
several macros. Most synopses specify a family of functions consisting of a principal
are floating types at least as wide as float and double, respectively, and such that
double_t is at least as wide as float_t. If FLT_EVAL_METHOD equals 0,
float_t and double_t are float and double, respectively; if
are floating types at least as wide as float and double, respectively, and such that
double_t is at least as wide as float_t. If FLT_EVAL_METHOD equals 0,
float_t and double_t are float and double, respectively; if
expands to a constant expression of type float representing positive or unsigned
infinity, if available; else to a positive constant of type float that overflows at
expands to a constant expression of type float representing positive or unsigned
infinity, if available; else to a positive constant of type float that overflows at
is defined if and only if the implementation supports quiet NaNs for the float type. It
expands to a constant expression of type float representing a quiet NaN.
<p><!--para 6 -->
is defined if and only if the implementation supports quiet NaNs for the float type. It
expands to a constant expression of type float representing a quiet NaN.
<p><!--para 6 -->
represent the mutually exclusive kinds of floating-point values. They expand to integer
constant expressions with distinct values. Additional implementation-defined floating-
point classifications, with macro definitions beginning with FP_ and an uppercase letter,
represent the mutually exclusive kinds of floating-point values. They expand to integer
constant expressions with distinct values. Additional implementation-defined floating-
point classifications, with macro definitions beginning with FP_ and an uppercase letter,
is optionally defined. If defined, it indicates that the fma function generally executes
about as fast as, or faster than, a multiply and an add of double operands.<sup><a href="#note202"><b>202)</b></a></sup> The
macros
<pre>
FP_FAST_FMAF
is optionally defined. If defined, it indicates that the fma function generally executes
about as fast as, or faster than, a multiply and an add of double operands.<sup><a href="#note202"><b>202)</b></a></sup> The
macros
<pre>
FP_FAST_FMAF
are, respectively, float and long double analogs of FP_FAST_FMA. If defined,
these macros expand to the integer constant 1.
<p><!--para 8 -->
The macros
<pre>
FP_ILOGB0
are, respectively, float and long double analogs of FP_FAST_FMA. If defined,
these macros expand to the integer constant 1.
<p><!--para 8 -->
The macros
<pre>
FP_ILOGB0
expand to integer constant expressions whose values are returned by ilogb(x) if x is
zero or NaN, respectively. The value of FP_ILOGB0 shall be either INT_MIN or
-INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN.
expand to integer constant expressions whose values are returned by ilogb(x) if x is
zero or NaN, respectively. The value of FP_ILOGB0 shall be either INT_MIN or
-INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN.
expands to an expression that has type int and the value MATH_ERRNO,
MATH_ERREXCEPT, or the bitwise OR of both. The value of math_errhandling is
constant for the duration of the program. It is unspecified whether
expands to an expression that has type int and the value MATH_ERRNO,
MATH_ERREXCEPT, or the bitwise OR of both. The value of math_errhandling is
constant for the duration of the program. It is unspecified whether
shall define the macros FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in
<a href="#7.6"><fenv.h></a>.
shall define the macros FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in
<a href="#7.6"><fenv.h></a>.
<p><small><a name="note198" href="#note198">198)</a> Particularly on systems with wide expression evaluation, a <a href="#7.12"><math.h></a> function might pass arguments
and return values in wider format than the synopsis prototype indicates.
</small>
<p><small><a name="note198" href="#note198">198)</a> Particularly on systems with wide expression evaluation, a <a href="#7.12"><math.h></a> function might pass arguments
and return values in wider format than the synopsis prototype indicates.
</small>
math_errhandling & MATH_ERREXCEPT is nonzero, whether the ''underflow''
floating-point exception is raised is implementation-defined.
math_errhandling & MATH_ERREXCEPT is nonzero, whether the ''underflow''
floating-point exception is raised is implementation-defined.
<p><small><a name="note203" href="#note203">203)</a> 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.
</small>
<p><small><a name="note203" href="#note203">203)</a> 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.
</small>
<p><!--para 2 -->
The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the
state is ''off'') the implementation to contract expressions (<a href="#6.5">6.5</a>). Each pragma can occur
<p><!--para 2 -->
The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the
state is ''off'') the implementation to contract expressions (<a href="#6.5">6.5</a>). Each pragma can occur
expression of real floating type.
<h5><a name="7.12.3.1" href="#7.12.3.1">7.12.3.1 The fpclassify macro</a></h5>
expression of real floating type.
<h5><a name="7.12.3.1" href="#7.12.3.1">7.12.3.1 The fpclassify macro</a></h5>
<p><!--para 2 -->
The fpclassify macro classifies its argument value as NaN, infinite, normal,
subnormal, zero, or into another implementation-defined category. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then classification is based on the type of the argument.<sup><a href="#note205"><b>205)</b></a></sup>
<p><!--para 2 -->
The fpclassify macro classifies its argument value as NaN, infinite, normal,
subnormal, zero, or into another implementation-defined category. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then classification is based on the type of the argument.<sup><a href="#note205"><b>205)</b></a></sup>
<p><!--para 3 -->
The fpclassify macro returns the value of the number classification macro
appropriate to the value of its argument.
<p><!--para 3 -->
The fpclassify macro returns the value of the number classification macro
appropriate to the value of its argument.
#define fpclassify(x) \
((sizeof (x) == sizeof (float)) ? __fpclassifyf(x) : \
(sizeof (x) == sizeof (double)) ? __fpclassifyd(x) : \
#define fpclassify(x) \
((sizeof (x) == sizeof (float)) ? __fpclassifyf(x) : \
(sizeof (x) == sizeof (double)) ? __fpclassifyd(x) : \
<p><small><a name="note205" href="#note205">205)</a> 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.
</small>
<h5><a name="7.12.3.2" href="#7.12.3.2">7.12.3.2 The isfinite macro</a></h5>
<p><small><a name="note205" href="#note205">205)</a> 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.
</small>
<h5><a name="7.12.3.2" href="#7.12.3.2">7.12.3.2 The isfinite macro</a></h5>
<p><!--para 2 -->
The isfinite macro determines whether its argument has a finite value (zero,
subnormal, or normal, and not infinite or NaN). First, an argument represented in a
<p><!--para 2 -->
The isfinite macro determines whether its argument has a finite value (zero,
subnormal, or normal, and not infinite or NaN). First, an argument represented in a
<p><!--para 3 -->
The isfinite macro returns a nonzero value if and only if its argument has a finite
value.
<h5><a name="7.12.3.3" href="#7.12.3.3">7.12.3.3 The isinf macro</a></h5>
<p><!--para 3 -->
The isfinite macro returns a nonzero value if and only if its argument has a finite
value.
<h5><a name="7.12.3.3" href="#7.12.3.3">7.12.3.3 The isinf macro</a></h5>
<p><!--para 2 -->
The isinf macro determines whether its argument value is an infinity (positive or
negative). First, an argument represented in a format wider than its semantic type is
converted to its semantic type. Then determination is based on the type of the argument.
<p><!--para 2 -->
The isinf macro determines whether its argument value is an infinity (positive or
negative). First, an argument represented in a format wider than its semantic type is
converted to its semantic type. Then determination is based on the type of the argument.
<p><!--para 3 -->
The isinf macro returns a nonzero value if and only if its argument has an infinite
value.
<h5><a name="7.12.3.4" href="#7.12.3.4">7.12.3.4 The isnan macro</a></h5>
<p><!--para 3 -->
The isinf macro returns a nonzero value if and only if its argument has an infinite
value.
<h5><a name="7.12.3.4" href="#7.12.3.4">7.12.3.4 The isnan macro</a></h5>
<p><!--para 2 -->
The isnan macro determines whether its argument value is a NaN. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then determination is based on the type of the argument.<sup><a href="#note206"><b>206)</b></a></sup>
<p><!--para 2 -->
The isnan macro determines whether its argument value is a NaN. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then determination is based on the type of the argument.<sup><a href="#note206"><b>206)</b></a></sup>
<p><small><a name="note206" href="#note206">206)</a> 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.
</small>
<h5><a name="7.12.3.5" href="#7.12.3.5">7.12.3.5 The isnormal macro</a></h5>
<p><small><a name="note206" href="#note206">206)</a> 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.
</small>
<h5><a name="7.12.3.5" href="#7.12.3.5">7.12.3.5 The isnormal macro</a></h5>
<p><!--para 2 -->
The isnormal macro determines whether its argument value is normal (neither zero,
subnormal, infinite, nor NaN). First, an argument represented in a format wider than its
semantic type is converted to its semantic type. Then determination is based on the type
of the argument.
<p><!--para 2 -->
The isnormal macro determines whether its argument value is normal (neither zero,
subnormal, infinite, nor NaN). First, an argument represented in a format wider than its
semantic type is converted to its semantic type. Then determination is based on the type
of the argument.
<p><!--para 3 -->
The isnormal macro returns a nonzero value if and only if its argument has a normal
value.
<h5><a name="7.12.3.6" href="#7.12.3.6">7.12.3.6 The signbit macro</a></h5>
<p><!--para 3 -->
The isnormal macro returns a nonzero value if and only if its argument has a normal
value.
<h5><a name="7.12.3.6" href="#7.12.3.6">7.12.3.6 The signbit macro</a></h5>
<p><small><a name="note207" href="#note207">207)</a> The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
unsigned, it is treated as positive.
</small>
<p><small><a name="note207" href="#note207">207)</a> The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
unsigned, it is treated as positive.
</small>
<h4><a name="7.12.4" href="#7.12.4">7.12.4 Trigonometric functions</a></h4>
<h5><a name="7.12.4.1" href="#7.12.4.1">7.12.4.1 The acos functions</a></h5>
<h4><a name="7.12.4" href="#7.12.4">7.12.4 Trigonometric functions</a></h4>
<h5><a name="7.12.4.1" href="#7.12.4.1">7.12.4.1 The acos functions</a></h5>
<p><!--para 2 -->
The acos functions compute the principal value of the arc cosine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<p><!--para 2 -->
The acos functions compute the principal value of the arc cosine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<p><!--para 2 -->
The asin functions compute the principal value of the arc sine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<p><!--para 2 -->
The asin functions compute the principal value of the arc sine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<p><!--para 3 -->
The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
<h5><a name="7.12.4.3" href="#7.12.4.3">7.12.4.3 The atan functions</a></h5>
<p><!--para 3 -->
The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
<h5><a name="7.12.4.3" href="#7.12.4.3">7.12.4.3 The atan functions</a></h5>
<p><!--para 3 -->
The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
<h5><a name="7.12.4.4" href="#7.12.4.4">7.12.4.4 The atan2 functions</a></h5>
<p><!--para 3 -->
The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
<h5><a name="7.12.4.4" href="#7.12.4.4">7.12.4.4 The atan2 functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan2(double y, double x);
float atan2f(float y, float x);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan2(double y, double x);
float atan2f(float y, float x);
<p><!--para 2 -->
The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
arguments to determine the quadrant of the return value. A domain error may occur if
both arguments are zero.
<p><!--para 2 -->
The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
arguments to determine the quadrant of the return value. A domain error may occur if
both arguments are zero.
<p><!--para 3 -->
The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
<!--page 232 -->
<h5><a name="7.12.4.5" href="#7.12.4.5">7.12.4.5 The cos functions</a></h5>
<p><!--para 3 -->
The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
<!--page 232 -->
<h5><a name="7.12.4.5" href="#7.12.4.5">7.12.4.5 The cos functions</a></h5>
<p><!--para 3 -->
The cos functions return cos x.
<h5><a name="7.12.4.6" href="#7.12.4.6">7.12.4.6 The sin functions</a></h5>
<p><!--para 3 -->
The cos functions return cos x.
<h5><a name="7.12.4.6" href="#7.12.4.6">7.12.4.6 The sin functions</a></h5>
<p><!--para 3 -->
The sin functions return sin x.
<h5><a name="7.12.4.7" href="#7.12.4.7">7.12.4.7 The tan functions</a></h5>
<p><!--para 3 -->
The sin functions return sin x.
<h5><a name="7.12.4.7" href="#7.12.4.7">7.12.4.7 The tan functions</a></h5>
<h4><a name="7.12.5" href="#7.12.5">7.12.5 Hyperbolic functions</a></h4>
<h5><a name="7.12.5.1" href="#7.12.5.1">7.12.5.1 The acosh functions</a></h5>
<h4><a name="7.12.5" href="#7.12.5">7.12.5 Hyperbolic functions</a></h4>
<h5><a name="7.12.5.1" href="#7.12.5.1">7.12.5.1 The acosh functions</a></h5>
<p><!--para 2 -->
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
error occurs for arguments less than 1.
<p><!--para 2 -->
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
error occurs for arguments less than 1.
<p><!--para 3 -->
The acosh functions return arcosh x in the interval [0, +(inf)].
<h5><a name="7.12.5.2" href="#7.12.5.2">7.12.5.2 The asinh functions</a></h5>
<p><!--para 3 -->
The acosh functions return arcosh x in the interval [0, +(inf)].
<h5><a name="7.12.5.2" href="#7.12.5.2">7.12.5.2 The asinh functions</a></h5>
<p><!--para 3 -->
The asinh functions return arsinh x.
<h5><a name="7.12.5.3" href="#7.12.5.3">7.12.5.3 The atanh functions</a></h5>
<p><!--para 3 -->
The asinh functions return arsinh x.
<h5><a name="7.12.5.3" href="#7.12.5.3">7.12.5.3 The atanh functions</a></h5>
<p><!--para 2 -->
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.
<!--page 234 -->
<p><!--para 2 -->
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.
<!--page 234 -->
<p><!--para 3 -->
The atanh functions return artanh x.
<h5><a name="7.12.5.4" href="#7.12.5.4">7.12.5.4 The cosh functions</a></h5>
<p><!--para 3 -->
The atanh functions return artanh x.
<h5><a name="7.12.5.4" href="#7.12.5.4">7.12.5.4 The cosh functions</a></h5>
<p><!--para 2 -->
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 2 -->
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 3 -->
The cosh functions return cosh x.
<h5><a name="7.12.5.5" href="#7.12.5.5">7.12.5.5 The sinh functions</a></h5>
<p><!--para 3 -->
The cosh functions return cosh x.
<h5><a name="7.12.5.5" href="#7.12.5.5">7.12.5.5 The sinh functions</a></h5>
<p><!--para 2 -->
The sinh functions compute the hyperbolic sine of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 2 -->
The sinh functions compute the hyperbolic sine of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 3 -->
The sinh functions return sinh x.
<h5><a name="7.12.5.6" href="#7.12.5.6">7.12.5.6 The tanh functions</a></h5>
<p><!--para 3 -->
The sinh functions return sinh x.
<h5><a name="7.12.5.6" href="#7.12.5.6">7.12.5.6 The tanh functions</a></h5>
<p><!--para 3 -->
The tanh functions return tanh x.
<h4><a name="7.12.6" href="#7.12.6">7.12.6 Exponential and logarithmic functions</a></h4>
<h5><a name="7.12.6.1" href="#7.12.6.1">7.12.6.1 The exp functions</a></h5>
<p><!--para 3 -->
The tanh functions return tanh x.
<h4><a name="7.12.6" href="#7.12.6">7.12.6 Exponential and logarithmic functions</a></h4>
<h5><a name="7.12.6.1" href="#7.12.6.1">7.12.6.1 The exp functions</a></h5>
<p><!--para 2 -->
The exp functions compute the base-e exponential of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 2 -->
The exp functions compute the base-e exponential of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 3 -->
The exp functions return e<sup>x</sup>.
<h5><a name="7.12.6.2" href="#7.12.6.2">7.12.6.2 The exp2 functions</a></h5>
<p><!--para 3 -->
The exp functions return e<sup>x</sup>.
<h5><a name="7.12.6.2" href="#7.12.6.2">7.12.6.2 The exp2 functions</a></h5>
<p><!--para 2 -->
The exp2 functions compute the base-2 exponential of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 2 -->
The exp2 functions compute the base-2 exponential of x. A range error occurs if the
magnitude of x is too large.
<p><!--para 3 -->
The exp2 functions return 2<sup>x</sup>.
<h5><a name="7.12.6.3" href="#7.12.6.3">7.12.6.3 The expm1 functions</a></h5>
<p><!--para 3 -->
The exp2 functions return 2<sup>x</sup>.
<h5><a name="7.12.6.3" href="#7.12.6.3">7.12.6.3 The expm1 functions</a></h5>
<p><!--para 2 -->
The expm1 functions compute the base-e exponential of the argument, minus 1. A range
error occurs if x is too large.<sup><a href="#note208"><b>208)</b></a></sup>
<p><!--para 2 -->
The expm1 functions compute the base-e exponential of the argument, minus 1. A range
error occurs if x is too large.<sup><a href="#note208"><b>208)</b></a></sup>
<p><small><a name="note208" href="#note208">208)</a> For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
</small>
<h5><a name="7.12.6.4" href="#7.12.6.4">7.12.6.4 The frexp functions</a></h5>
<p><small><a name="note208" href="#note208">208)</a> For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
</small>
<h5><a name="7.12.6.4" href="#7.12.6.4">7.12.6.4 The frexp functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double frexp(double value, int *exp);
float frexpf(float value, int *exp);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double frexp(double value, int *exp);
float frexpf(float value, int *exp);
<p><!--para 2 -->
The frexp functions break a floating-point number into a normalized fraction and an
integral power of 2. They store the integer in the int object pointed to by exp.
<p><!--para 2 -->
The frexp functions break a floating-point number into a normalized fraction and an
integral power of 2. They store the integer in the int object pointed to by exp.
<p><!--para 3 -->
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<sup>*exp</sup> . If value is zero, both parts of the result are zero.
<h5><a name="7.12.6.5" href="#7.12.6.5">7.12.6.5 The ilogb functions</a></h5>
<p><!--para 3 -->
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<sup>*exp</sup> . If value is zero, both parts of the result are zero.
<h5><a name="7.12.6.5" href="#7.12.6.5">7.12.6.5 The ilogb functions</a></h5>
<p><!--para 2 -->
The ilogb functions extract the exponent of x as a signed int value. If x is zero they
compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is
<p><!--para 2 -->
The ilogb functions extract the exponent of x as a signed int value. If x is zero they
compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is
<p><!--para 3 -->
The ilogb functions return the exponent of x as a signed int value.
<p><b> Forward references</b>: the logb functions (<a href="#7.12.6.11">7.12.6.11</a>).
<h5><a name="7.12.6.6" href="#7.12.6.6">7.12.6.6 The ldexp functions</a></h5>
<p><!--para 3 -->
The ilogb functions return the exponent of x as a signed int value.
<p><b> Forward references</b>: the logb functions (<a href="#7.12.6.11">7.12.6.11</a>).
<h5><a name="7.12.6.6" href="#7.12.6.6">7.12.6.6 The ldexp functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
<p><!--para 3 -->
The ldexp functions return x 2<sup>exp</sup> .
<h5><a name="7.12.6.7" href="#7.12.6.7">7.12.6.7 The log functions</a></h5>
<p><!--para 3 -->
The ldexp functions return x 2<sup>exp</sup> .
<h5><a name="7.12.6.7" href="#7.12.6.7">7.12.6.7 The log functions</a></h5>
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
<p><!--para 3 -->
The log functions return loge x.
<h5><a name="7.12.6.8" href="#7.12.6.8">7.12.6.8 The log10 functions</a></h5>
<p><!--para 3 -->
The log functions return loge x.
<h5><a name="7.12.6.8" href="#7.12.6.8">7.12.6.8 The log10 functions</a></h5>
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
<p><!--para 3 -->
The log10 functions return log10 x.
<h5><a name="7.12.6.9" href="#7.12.6.9">7.12.6.9 The log1p functions</a></h5>
<p><!--para 3 -->
The log10 functions return log10 x.
<h5><a name="7.12.6.9" href="#7.12.6.9">7.12.6.9 The log1p functions</a></h5>
<p><!--para 2 -->
The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.<sup><a href="#note209"><b>209)</b></a></sup>
A domain error occurs if the argument is less than -1. A range error may occur if the
argument equals -1.
<p><!--para 2 -->
The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.<sup><a href="#note209"><b>209)</b></a></sup>
A domain error occurs if the argument is less than -1. A range error may occur if the
argument equals -1.
<p><small><a name="note209" href="#note209">209)</a> For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
</small>
<h5><a name="7.12.6.10" href="#7.12.6.10">7.12.6.10 The log2 functions</a></h5>
<p><small><a name="note209" href="#note209">209)</a> For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
</small>
<h5><a name="7.12.6.10" href="#7.12.6.10">7.12.6.10 The log2 functions</a></h5>
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
<p><!--para 2 -->
The logb functions extract the exponent of x, as a signed integer value in floating-point
format. If x is subnormal it is treated as though it were normalized; thus, for positive
finite x,
<pre>
<p><!--para 2 -->
The logb functions extract the exponent of x, as a signed integer value in floating-point
format. If x is subnormal it is treated as though it were normalized; thus, for positive
finite x,
<pre>
<p><!--para 3 -->
The logb functions return the signed exponent of x.
<h5><a name="7.12.6.12" href="#7.12.6.12">7.12.6.12 The modf functions</a></h5>
<p><!--para 3 -->
The logb functions return the signed exponent of x.
<h5><a name="7.12.6.12" href="#7.12.6.12">7.12.6.12 The modf functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double modf(double value, double *iptr);
float modff(float value, float *iptr);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double modf(double value, double *iptr);
float modff(float value, float *iptr);
<p><!--para 2 -->
The modf functions break the argument value into integral and fractional parts, each of
which has the same type and sign as the argument. They store the integral part (in
floating-point format) in the object pointed to by iptr.
<p><!--para 2 -->
The modf functions break the argument value into integral and fractional parts, each of
which has the same type and sign as the argument. They store the integral part (in
floating-point format) in the object pointed to by iptr.
<p><!--para 3 -->
The modf functions return the signed fractional part of value.
<!--page 240 -->
<h5><a name="7.12.6.13" href="#7.12.6.13">7.12.6.13 The scalbn and scalbln functions</a></h5>
<p><!--para 3 -->
The modf functions return the signed fractional part of value.
<!--page 240 -->
<h5><a name="7.12.6.13" href="#7.12.6.13">7.12.6.13 The scalbn and scalbln functions</a></h5>
long double scalbnl(long double x, int n);
double scalbln(double x, long int n);
float scalblnf(float x, long int n);
long double scalbnl(long double x, int n);
double scalbln(double x, long int n);
float scalblnf(float x, long int n);
<p><!--para 2 -->
The scalbn and scalbln functions compute x FLT_RADIX<sup>n</sup> efficiently, not
normally by computing FLT_RADIX<sup>n</sup> explicitly. A range error may occur.
<p><!--para 2 -->
The scalbn and scalbln functions compute x FLT_RADIX<sup>n</sup> efficiently, not
normally by computing FLT_RADIX<sup>n</sup> explicitly. A range error may occur.
<p><!--para 3 -->
The scalbn and scalbln functions return x FLT_RADIX<sup>n</sup> .
<h4><a name="7.12.7" href="#7.12.7">7.12.7 Power and absolute-value functions</a></h4>
<h5><a name="7.12.7.1" href="#7.12.7.1">7.12.7.1 The cbrt functions</a></h5>
<p><!--para 3 -->
The scalbn and scalbln functions return x FLT_RADIX<sup>n</sup> .
<h4><a name="7.12.7" href="#7.12.7">7.12.7 Power and absolute-value functions</a></h4>
<h5><a name="7.12.7.1" href="#7.12.7.1">7.12.7.1 The cbrt functions</a></h5>
<p><!--para 3 -->
The cbrt functions return x<sup>1/3</sup>.
<h5><a name="7.12.7.2" href="#7.12.7.2">7.12.7.2 The fabs functions</a></h5>
<p><!--para 3 -->
The cbrt functions return x<sup>1/3</sup>.
<h5><a name="7.12.7.2" href="#7.12.7.2">7.12.7.2 The fabs functions</a></h5>
<p><!--para 3 -->
The fabs functions return | x |.
<h5><a name="7.12.7.3" href="#7.12.7.3">7.12.7.3 The hypot functions</a></h5>
<p><!--para 3 -->
The fabs functions return | x |.
<h5><a name="7.12.7.3" href="#7.12.7.3">7.12.7.3 The hypot functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double hypot(double x, double y);
float hypotf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double hypot(double x, double y);
float hypotf(float x, float y);
<p><!--para 2 -->
The hypot functions compute the square root of the sum of the squares of x and y,
without undue overflow or underflow. A range error may occur.
<p><!--para 3 -->
<p><!--para 2 -->
The hypot functions compute the square root of the sum of the squares of x and y,
without undue overflow or underflow. A range error may occur.
<p><!--para 3 -->
<p><!--para 4 -->
The hypot functions return (sqrt)(x<sup>2</sup> + y<sup>2</sup>).
<h5><a name="7.12.7.4" href="#7.12.7.4">7.12.7.4 The pow functions</a></h5>
<p><!--para 4 -->
The hypot functions return (sqrt)(x<sup>2</sup> + y<sup>2</sup>).
<h5><a name="7.12.7.4" href="#7.12.7.4">7.12.7.4 The pow functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double pow(double x, double y);
float powf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double pow(double x, double y);
float powf(float x, float y);
<p><!--para 2 -->
The pow functions compute x raised to the power y. A domain error occurs if x is finite
and negative and y is finite and not an integer value. A range error may occur. A domain
error may occur if x is zero and y is zero. A domain error or range error may occur if x
is zero and y is less than zero.
<p><!--para 2 -->
The pow functions compute x raised to the power y. A domain error occurs if x is finite
and negative and y is finite and not an integer value. A range error may occur. A domain
error may occur if x is zero and y is zero. A domain error or range error may occur if x
is zero and y is less than zero.
<p><!--para 3 -->
The pow functions return x<sup>y</sup>.
<h5><a name="7.12.7.5" href="#7.12.7.5">7.12.7.5 The sqrt functions</a></h5>
<p><!--para 3 -->
The pow functions return x<sup>y</sup>.
<h5><a name="7.12.7.5" href="#7.12.7.5">7.12.7.5 The sqrt functions</a></h5>
<p><!--para 2 -->
The sqrt functions compute the nonnegative square root of x. A domain error occurs if
the argument is less than zero.
<p><!--para 2 -->
The sqrt functions compute the nonnegative square root of x. A domain error occurs if
the argument is less than zero.
<p><!--para 3 -->
The sqrt functions return (sqrt)(x).
<h4><a name="7.12.8" href="#7.12.8">7.12.8 Error and gamma functions</a></h4>
<h5><a name="7.12.8.1" href="#7.12.8.1">7.12.8.1 The erf functions</a></h5>
<p><!--para 3 -->
The sqrt functions return (sqrt)(x).
<h4><a name="7.12.8" href="#7.12.8">7.12.8 Error and gamma functions</a></h4>
<h5><a name="7.12.8.1" href="#7.12.8.1">7.12.8.1 The erf functions</a></h5>
<p><!--para 2 -->
The erfc functions compute the complementary error function of x. A range error
occurs if x is too large.
<p><!--para 2 -->
The erfc functions compute the complementary error function of x. A range error
occurs if x is too large.
<p><!--para 2 -->
The lgamma functions compute the natural logarithm of the absolute value of gamma of
x. A range error occurs if x is too large. A range error may occur if x is a negative
integer or zero.
<p><!--para 2 -->
The lgamma functions compute the natural logarithm of the absolute value of gamma of
x. A range error occurs if x is too large. A range error may occur if x is a negative
integer or zero.
<p><!--para 3 -->
The lgamma functions return loge | (Gamma)(x) |.
<h5><a name="7.12.8.4" href="#7.12.8.4">7.12.8.4 The tgamma functions</a></h5>
<p><!--para 3 -->
The lgamma functions return loge | (Gamma)(x) |.
<h5><a name="7.12.8.4" href="#7.12.8.4">7.12.8.4 The tgamma functions</a></h5>
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
<p><!--para 3 -->
The tgamma functions return (Gamma)(x).
<h4><a name="7.12.9" href="#7.12.9">7.12.9 Nearest integer functions</a></h4>
<h5><a name="7.12.9.1" href="#7.12.9.1">7.12.9.1 The ceil functions</a></h5>
<p><!--para 3 -->
The tgamma functions return (Gamma)(x).
<h4><a name="7.12.9" href="#7.12.9">7.12.9 Nearest integer functions</a></h4>
<h5><a name="7.12.9.1" href="#7.12.9.1">7.12.9.1 The ceil functions</a></h5>
<p><!--para 3 -->
The ceil functions return [^x^], expressed as a floating-point number.
<h5><a name="7.12.9.2" href="#7.12.9.2">7.12.9.2 The floor functions</a></h5>
<p><!--para 3 -->
The ceil functions return [^x^], expressed as a floating-point number.
<h5><a name="7.12.9.2" href="#7.12.9.2">7.12.9.2 The floor functions</a></h5>
<p><!--para 3 -->
The floor functions return [_x_], expressed as a floating-point number.
<h5><a name="7.12.9.3" href="#7.12.9.3">7.12.9.3 The nearbyint functions</a></h5>
<p><!--para 3 -->
The floor functions return [_x_], expressed as a floating-point number.
<h5><a name="7.12.9.3" href="#7.12.9.3">7.12.9.3 The nearbyint functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nearbyint(double x);
float nearbyintf(float x);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nearbyint(double x);
float nearbyintf(float x);
<p><!--para 2 -->
The nearbyint functions round their argument to an integer value in floating-point
format, using the current rounding direction and without raising the ''inexact'' floating-
point exception.
<p><!--para 2 -->
The nearbyint functions round their argument to an integer value in floating-point
format, using the current rounding direction and without raising the ''inexact'' floating-
point exception.
<p><!--para 3 -->
The nearbyint functions return the rounded integer value.
<h5><a name="7.12.9.4" href="#7.12.9.4">7.12.9.4 The rint functions</a></h5>
<p><!--para 3 -->
The nearbyint functions return the rounded integer value.
<h5><a name="7.12.9.4" href="#7.12.9.4">7.12.9.4 The rint functions</a></h5>
<p><!--para 2 -->
The rint functions differ from the nearbyint functions (<a href="#7.12.9.3">7.12.9.3</a>) only in that the
rint functions may raise the ''inexact'' floating-point exception if the result differs in
value from the argument.
<!--page 245 -->
<p><!--para 2 -->
The rint functions differ from the nearbyint functions (<a href="#7.12.9.3">7.12.9.3</a>) only in that the
rint functions may raise the ''inexact'' floating-point exception if the result differs in
value from the argument.
<!--page 245 -->
<p><!--para 3 -->
The rint functions return the rounded integer value.
<h5><a name="7.12.9.5" href="#7.12.9.5">7.12.9.5 The lrint and llrint functions</a></h5>
<p><!--para 3 -->
The rint functions return the rounded integer value.
<h5><a name="7.12.9.5" href="#7.12.9.5">7.12.9.5 The lrint and llrint functions</a></h5>
long int lrintl(long double x);
long long int llrint(double x);
long long int llrintf(float x);
long int lrintl(long double x);
long long int llrint(double x);
long long int llrintf(float x);
<p><!--para 2 -->
The lrint and llrint functions round their argument to the nearest integer value,
rounding according to the current rounding direction. If the rounded value is outside the
range of the return type, the numeric result is unspecified and a domain error or range
error may occur. *
<p><!--para 2 -->
The lrint and llrint functions round their argument to the nearest integer value,
rounding according to the current rounding direction. If the rounded value is outside the
range of the return type, the numeric result is unspecified and a domain error or range
error may occur. *
<p><!--para 3 -->
The lrint and llrint functions return the rounded integer value.
<h5><a name="7.12.9.6" href="#7.12.9.6">7.12.9.6 The round functions</a></h5>
<p><!--para 3 -->
The lrint and llrint functions return the rounded integer value.
<h5><a name="7.12.9.6" href="#7.12.9.6">7.12.9.6 The round functions</a></h5>
<p><!--para 2 -->
The round functions round their argument to the nearest integer value in floating-point
format, rounding halfway cases away from zero, regardless of the current rounding
direction.
<p><!--para 2 -->
The round functions round their argument to the nearest integer value in floating-point
format, rounding halfway cases away from zero, regardless of the current rounding
direction.
<p><!--para 3 -->
The round functions return the rounded integer value.
<!--page 246 -->
<h5><a name="7.12.9.7" href="#7.12.9.7">7.12.9.7 The lround and llround functions</a></h5>
<p><!--para 3 -->
The round functions return the rounded integer value.
<!--page 246 -->
<h5><a name="7.12.9.7" href="#7.12.9.7">7.12.9.7 The lround and llround functions</a></h5>
long int lroundl(long double x);
long long int llround(double x);
long long int llroundf(float x);
long int lroundl(long double x);
long long int llround(double x);
long long int llroundf(float x);
<p><!--para 2 -->
The lround and llround functions round their argument to the nearest integer value,
rounding halfway cases away from zero, regardless of the current rounding direction. If
the rounded value is outside the range of the return type, the numeric result is unspecified
and a domain error or range error may occur.
<p><!--para 2 -->
The lround and llround functions round their argument to the nearest integer value,
rounding halfway cases away from zero, regardless of the current rounding direction. If
the rounded value is outside the range of the return type, the numeric result is unspecified
and a domain error or range error may occur.
<p><!--para 3 -->
The lround and llround functions return the rounded integer value.
<h5><a name="7.12.9.8" href="#7.12.9.8">7.12.9.8 The trunc functions</a></h5>
<p><!--para 3 -->
The lround and llround functions return the rounded integer value.
<h5><a name="7.12.9.8" href="#7.12.9.8">7.12.9.8 The trunc functions</a></h5>
<p><!--para 2 -->
The trunc functions round their argument to the integer value, in floating format,
nearest to but no larger in magnitude than the argument.
<p><!--para 2 -->
The trunc functions round their argument to the integer value, in floating format,
nearest to but no larger in magnitude than the argument.
<h4><a name="7.12.10" href="#7.12.10">7.12.10 Remainder functions</a></h4>
<h5><a name="7.12.10.1" href="#7.12.10.1">7.12.10.1 The fmod functions</a></h5>
<h4><a name="7.12.10" href="#7.12.10">7.12.10 Remainder functions</a></h4>
<h5><a name="7.12.10.1" href="#7.12.10.1">7.12.10.1 The fmod functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmod(double x, double y);
float fmodf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmod(double x, double y);
float fmodf(float x, float y);
<p><!--para 3 -->
The fmod functions return the value x - ny, for some integer n such that, if y is nonzero,
the result has the same sign as x and magnitude less than the magnitude of y. If y is zero,
<p><!--para 3 -->
The fmod functions return the value x - ny, for some integer n such that, if y is nonzero,
the result has the same sign as x and magnitude less than the magnitude of y. If y is zero,
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remainder(double x, double y);
float remainderf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remainder(double x, double y);
float remainderf(float x, float y);
<p><!--para 3 -->
The remainder functions return x REM y. If y is zero, whether a domain error occurs
or the functions return zero is implementation defined.
<p><!--para 3 -->
The remainder functions return x REM y. If y is zero, whether a domain error occurs
or the functions return zero is implementation defined.
<p><small><a name="note210" href="#note210">210)</a> ''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
<p><small><a name="note210" href="#note210">210)</a> ''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
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remquo(double x, double y, int *quo);
float remquof(float x, float y, int *quo);
long double remquol(long double x, long double y,
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remquo(double x, double y, int *quo);
float remquof(float x, float y, int *quo);
long double remquol(long double x, long double y,
<p><!--para 2 -->
The remquo functions compute the same remainder as the remainder functions. In
the object pointed to by quo they store a value whose sign is the sign of x/y and whose
magnitude is congruent modulo 2<sup>n</sup> to the magnitude of the integral quotient of x/y, where
n is an implementation-defined integer greater than or equal to 3.
<p><!--para 2 -->
The remquo functions compute the same remainder as the remainder functions. In
the object pointed to by quo they store a value whose sign is the sign of x/y and whose
magnitude is congruent modulo 2<sup>n</sup> to the magnitude of the integral quotient of x/y, where
n is an implementation-defined integer greater than or equal to 3.
<p><!--para 3 -->
The remquo functions return x REM y. If y is zero, the value stored in the object
pointed to by quo is unspecified and whether a domain error occurs or the functions
<p><!--para 3 -->
The remquo functions return x REM y. If y is zero, the value stored in the object
pointed to by quo is unspecified and whether a domain error occurs or the functions
<h4><a name="7.12.11" href="#7.12.11">7.12.11 Manipulation functions</a></h4>
<h5><a name="7.12.11.1" href="#7.12.11.1">7.12.11.1 The copysign functions</a></h5>
<h4><a name="7.12.11" href="#7.12.11">7.12.11 Manipulation functions</a></h4>
<h5><a name="7.12.11.1" href="#7.12.11.1">7.12.11.1 The copysign functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double copysign(double x, double y);
float copysignf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double copysign(double x, double y);
float copysignf(float x, float y);
<p><!--para 2 -->
The copysign functions produce a value with the magnitude of x and the sign of y.
They produce a NaN (with the sign of y) if x is a NaN. On implementations that
represent a signed zero but do not treat negative zero consistently in arithmetic
operations, the copysign functions regard the sign of zero as positive.
<p><!--para 2 -->
The copysign functions produce a value with the magnitude of x and the sign of y.
They produce a NaN (with the sign of y) if x is a NaN. On implementations that
represent a signed zero but do not treat negative zero consistently in arithmetic
operations, the copysign functions regard the sign of zero as positive.
<p><!--para 3 -->
The copysign functions return a value with the magnitude of x and the sign of y.
<!--page 249 -->
<h5><a name="7.12.11.2" href="#7.12.11.2">7.12.11.2 The nan functions</a></h5>
<p><!--para 3 -->
The copysign functions return a value with the magnitude of x and the sign of y.
<!--page 249 -->
<h5><a name="7.12.11.2" href="#7.12.11.2">7.12.11.2 The nan functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nan(const char *tagp);
float nanf(const char *tagp);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nan(const char *tagp);
float nanf(const char *tagp);
<p><!--para 2 -->
The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char-
sequence)", (char**) NULL); the call nan("") is equivalent to
<p><!--para 2 -->
The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char-
sequence)", (char**) NULL); the call nan("") is equivalent to
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.
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.
<p><!--para 3 -->
The nan functions return a quiet NaN, if available, with content indicated through tagp.
If the implementation does not support quiet NaNs, the functions return zero.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>).
<h5><a name="7.12.11.3" href="#7.12.11.3">7.12.11.3 The nextafter functions</a></h5>
<p><!--para 3 -->
The nan functions return a quiet NaN, if available, with content indicated through tagp.
If the implementation does not support quiet NaNs, the functions return zero.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>).
<h5><a name="7.12.11.3" href="#7.12.11.3">7.12.11.3 The nextafter functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nextafter(double x, double y);
float nextafterf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nextafter(double x, double y);
float nextafterf(float x, float y);
<p><!--para 2 -->
The nextafter functions determine the next representable value, in the type of the
function, after x in the direction of y, where x and y are first converted to the type of the
function.<sup><a href="#note211"><b>211)</b></a></sup> 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.
<p><!--para 2 -->
The nextafter functions determine the next representable value, in the type of the
function, after x in the direction of y, where x and y are first converted to the type of the
function.<sup><a href="#note211"><b>211)</b></a></sup> 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.
<p><!--para 3 -->
The nextafter functions return the next representable value in the specified format
after x in the direction of y.
<p><!--para 3 -->
The nextafter functions return the next representable value in the specified format
after x in the direction of y.
<p><small><a name="note211" href="#note211">211)</a> The argument values are converted to the type of the function, even by a macro implementation of the
function.
</small>
<h5><a name="7.12.11.4" href="#7.12.11.4">7.12.11.4 The nexttoward functions</a></h5>
<p><small><a name="note211" href="#note211">211)</a> The argument values are converted to the type of the function, even by a macro implementation of the
function.
</small>
<h5><a name="7.12.11.4" href="#7.12.11.4">7.12.11.4 The nexttoward functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nexttoward(double x, long double y);
float nexttowardf(float x, long double y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nexttoward(double x, long double y);
float nexttowardf(float x, long double y);
<p><!--para 2 -->
The nexttoward functions are equivalent to the nextafter functions except that the
second parameter has type long double and the functions return y converted to the
type of the function if x equals y.<sup><a href="#note212"><b>212)</b></a></sup>
<p><!--para 2 -->
The nexttoward functions are equivalent to the nextafter functions except that the
second parameter has type long double and the functions return y converted to the
type of the function if x equals y.<sup><a href="#note212"><b>212)</b></a></sup>
<p><small><a name="note212" href="#note212">212)</a> 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.
</small>
<p><small><a name="note212" href="#note212">212)</a> 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.
</small>
<h4><a name="7.12.12" href="#7.12.12">7.12.12 Maximum, minimum, and positive difference functions</a></h4>
<h5><a name="7.12.12.1" href="#7.12.12.1">7.12.12.1 The fdim functions</a></h5>
<h4><a name="7.12.12" href="#7.12.12">7.12.12 Maximum, minimum, and positive difference functions</a></h4>
<h5><a name="7.12.12.1" href="#7.12.12.1">7.12.12.1 The fdim functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fdim(double x, double y);
float fdimf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fdim(double x, double y);
float fdimf(float x, float y);
<p><!--para 3 -->
The fdim functions return the positive difference value.
<h5><a name="7.12.12.2" href="#7.12.12.2">7.12.12.2 The fmax functions</a></h5>
<p><!--para 3 -->
The fdim functions return the positive difference value.
<h5><a name="7.12.12.2" href="#7.12.12.2">7.12.12.2 The fmax functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmax(double x, double y);
float fmaxf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmax(double x, double y);
float fmaxf(float x, float y);
<p><small><a name="note213" href="#note213">213)</a> 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 <a href="#F.9.9.2">F.9.9.2</a>.
</small>
<h5><a name="7.12.12.3" href="#7.12.12.3">7.12.12.3 The fmin functions</a></h5>
<p><small><a name="note213" href="#note213">213)</a> 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 <a href="#F.9.9.2">F.9.9.2</a>.
</small>
<h5><a name="7.12.12.3" href="#7.12.12.3">7.12.12.3 The fmin functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmin(double x, double y);
float fminf(float x, float y);
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmin(double x, double y);
float fminf(float x, float y);
<p><small><a name="note214" href="#note214">214)</a> The fmin functions are analogous to the fmax functions in their treatment of NaNs.
</small>
<h4><a name="7.12.13" href="#7.12.13">7.12.13 Floating multiply-add</a></h4>
<h5><a name="7.12.13.1" href="#7.12.13.1">7.12.13.1 The fma functions</a></h5>
<p><small><a name="note214" href="#note214">214)</a> The fmin functions are analogous to the fmax functions in their treatment of NaNs.
</small>
<h4><a name="7.12.13" href="#7.12.13">7.12.13 Floating multiply-add</a></h4>
<h5><a name="7.12.13.1" href="#7.12.13.1">7.12.13.1 The fma functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fma(double x, double y, double z);
float fmaf(float x, float y, float z);
long double fmal(long double x, long double y,
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fma(double x, double y, double z);
float fmaf(float x, float y, float z);
long double fmal(long double x, long double y,
<p><!--para 2 -->
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.
<p><!--para 2 -->
The fma functions compute (x y) + z, rounded as one ternary operation: they compute
the value (as if) to infinite precision and round once to the result format, according to the
current rounding mode. A range error may occur.
the synopses in this subclause, real-floating indicates that the argument shall be an
expression of real floating type.
the synopses in this subclause, real-floating indicates that the argument shall be an
expression of real floating type.
<p><small><a name="note215" href="#note215">215)</a> 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.
</small>
<h5><a name="7.12.14.1" href="#7.12.14.1">7.12.14.1 The isgreater macro</a></h5>
<p><small><a name="note215" href="#note215">215)</a> 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.
</small>
<h5><a name="7.12.14.1" href="#7.12.14.1">7.12.14.1 The isgreater macro</a></h5>
<p><!--para 2 -->
The isgreater macro determines whether its first argument is greater than its second
argument. The value of isgreater(x, y) is always equal to (x) > (y); however,
unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<p><!--para 2 -->
The isgreater macro determines whether its first argument is greater than its second
argument. The value of isgreater(x, y) is always equal to (x) > (y); however,
unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<p><!--para 3 -->
The isgreater macro returns the value of (x) > (y).
<h5><a name="7.12.14.2" href="#7.12.14.2">7.12.14.2 The isgreaterequal macro</a></h5>
<p><!--para 3 -->
The isgreater macro returns the value of (x) > (y).
<h5><a name="7.12.14.2" href="#7.12.14.2">7.12.14.2 The isgreaterequal macro</a></h5>
<p><!--para 2 -->
The isgreaterequal macro determines whether its first argument is greater than or
equal to its second argument. The value of isgreaterequal(x, y) is always equal
<p><!--para 2 -->
The isgreaterequal macro determines whether its first argument is greater than or
equal to its second argument. The value of isgreaterequal(x, y) is always equal
<p><!--para 3 -->
The isgreaterequal macro returns the value of (x) >= (y).
<h5><a name="7.12.14.3" href="#7.12.14.3">7.12.14.3 The isless macro</a></h5>
<p><!--para 3 -->
The isgreaterequal macro returns the value of (x) >= (y).
<h5><a name="7.12.14.3" href="#7.12.14.3">7.12.14.3 The isless macro</a></h5>
<p><!--para 2 -->
The isless macro determines whether its first argument is less than its second
argument. The value of isless(x, y) is always equal to (x) < (y); however,
unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<p><!--para 2 -->
The isless macro determines whether its first argument is less than its second
argument. The value of isless(x, y) is always equal to (x) < (y); however,
unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<p><!--para 3 -->
The isless macro returns the value of (x) < (y).
<h5><a name="7.12.14.4" href="#7.12.14.4">7.12.14.4 The islessequal macro</a></h5>
<p><!--para 3 -->
The isless macro returns the value of (x) < (y).
<h5><a name="7.12.14.4" href="#7.12.14.4">7.12.14.4 The islessequal macro</a></h5>
<p><!--para 2 -->
The islessequal macro determines whether its first argument is less than or equal to
its second argument. The value of islessequal(x, y) is always equal to
(x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered.
<p><!--para 2 -->
The islessequal macro determines whether its first argument is less than or equal to
its second argument. The value of islessequal(x, y) is always equal to
(x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered.
<p><!--para 3 -->
The islessequal macro returns the value of (x) <= (y).
<h5><a name="7.12.14.5" href="#7.12.14.5">7.12.14.5 The islessgreater macro</a></h5>
<p><!--para 3 -->
The islessequal macro returns the value of (x) <= (y).
<h5><a name="7.12.14.5" href="#7.12.14.5">7.12.14.5 The islessgreater macro</a></h5>
<p><!--para 2 -->
The islessgreater macro determines whether its first argument is less than or
greater than its second argument. The islessgreater(x, y) macro is similar to
<p><!--para 2 -->
The islessgreater macro determines whether its first argument is less than or
greater than its second argument. The islessgreater(x, y) macro is similar to
<p><!--para 3 -->
The islessgreater macro returns the value of (x) < (y) || (x) > (y).
<h5><a name="7.12.14.6" href="#7.12.14.6">7.12.14.6 The isunordered macro</a></h5>
<p><!--para 3 -->
The islessgreater macro returns the value of (x) < (y) || (x) > (y).
<h5><a name="7.12.14.6" href="#7.12.14.6">7.12.14.6 The isunordered macro</a></h5>
<p><!--para 1 -->
The header <a href="#7.13"><setjmp.h></a> defines the macro setjmp, and declares one function and
one type, for bypassing the normal function call and return discipline.<sup><a href="#note216"><b>216)</b></a></sup>
<p><!--para 2 -->
The type declared is
<pre>
<p><!--para 1 -->
The header <a href="#7.13"><setjmp.h></a> defines the macro setjmp, and declares one function and
one type, for bypassing the normal function call and return discipline.<sup><a href="#note216"><b>216)</b></a></sup>
<p><!--para 2 -->
The type declared is
<pre>
which is an array type suitable for holding the information needed to restore a calling
environment. The environment of a call to the setjmp macro consists of information
sufficient for a call to the longjmp function to return execution to the correct block and
which is an array type suitable for holding the information needed to restore a calling
environment. The environment of a call to the setjmp macro consists of information
sufficient for a call to the longjmp function to return execution to the correct block and
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.
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.
<h4><a name="7.13.1" href="#7.13.1">7.13.1 Save calling environment</a></h4>
<h5><a name="7.13.1.1" href="#7.13.1.1">7.13.1.1 The setjmp macro</a></h5>
<h4><a name="7.13.1" href="#7.13.1">7.13.1 Save calling environment</a></h4>
<h5><a name="7.13.1.1" href="#7.13.1.1">7.13.1.1 The setjmp macro</a></h5>
<p><!--para 3 -->
If the return is from a direct invocation, the setjmp macro returns the value zero. If the
return is from a call to the longjmp function, the setjmp macro returns a nonzero
value.
<p><!--para 3 -->
If the return is from a direct invocation, the setjmp macro returns the value zero. If the
return is from a call to the longjmp function, the setjmp macro returns a nonzero
value.
<h4><a name="7.13.2" href="#7.13.2">7.13.2 Restore calling environment</a></h4>
<h5><a name="7.13.2.1" href="#7.13.2.1">7.13.2.1 The longjmp function</a></h5>
<h4><a name="7.13.2" href="#7.13.2">7.13.2 Restore calling environment</a></h4>
<h5><a name="7.13.2.1" href="#7.13.2.1">7.13.2.1 The longjmp function</a></h5>
<p><!--para 2 -->
The longjmp function restores the environment saved by the most recent invocation of
the setjmp macro in the same invocation of the program with the corresponding
<p><!--para 2 -->
The longjmp function restores the environment saved by the most recent invocation of
the setjmp macro in the same invocation of the program with the corresponding
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.
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.
<p><!--para 4 -->
After longjmp is completed, program execution continues as if the corresponding
invocation of the setjmp macro had just returned the value specified by val. The
<p><!--para 4 -->
After longjmp is completed, program execution continues as if the corresponding
invocation of the setjmp macro had just returned the value specified by val. The
{
int b[n]; // b may remain allocated
longjmp(buf, 2); // might cause memory loss
{
int b[n]; // b may remain allocated
longjmp(buf, 2); // might cause memory loss
<p><small><a name="note217" href="#note217">217)</a> 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.
</small>
<p><small><a name="note218" href="#note218">218)</a> This includes, but is not limited to, the floating-point status flags and the state of open files.
</small>
<p><small><a name="note217" href="#note217">217)</a> 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.
</small>
<p><small><a name="note218" href="#note218">218)</a> This includes, but is not limited to, the floating-point status flags and the state of open files.
</small>
<p><!--para 1 -->
The header <a href="#7.14"><signal.h></a> declares a type and two functions and defines several macros,
for handling various signals (conditions that may be reported during program execution).
<p><!--para 2 -->
The type defined is
<pre>
<p><!--para 1 -->
The header <a href="#7.14"><signal.h></a> declares a type and two functions and defines several macros,
for handling various signals (conditions that may be reported during program execution).
<p><!--para 2 -->
The type defined is
<pre>
which is the (possibly volatile-qualified) integer type of an object that can be accessed as
an atomic entity, even in the presence of asynchronous interrupts.
<p><!--para 3 -->
which is the (possibly volatile-qualified) integer type of an object that can be accessed as
an atomic entity, even in the presence of asynchronous interrupts.
<p><!--para 3 -->
which expand to constant expressions with distinct values that have type compatible with
the second argument to, and the return value of, the signal function, and whose values
compare unequal to the address of any declarable function; and the following, which
expand to positive integer constant expressions with type int and distinct values that are
the signal numbers, each corresponding to the specified condition:
which expand to constant expressions with distinct values that have type compatible with
the second argument to, and the return value of, the signal function, and whose values
compare unequal to the address of any declarable function; and the following, which
expand to positive integer constant expressions with type int and distinct values that are
the signal numbers, each corresponding to the specified condition:
<pre>
SIGABRT abnormal termination, such as is initiated by the abort function
SIGFPE an erroneous arithmetic operation, such as zero divide or an operation
<pre>
SIGABRT abnormal termination, such as is initiated by the abort function
SIGFPE an erroneous arithmetic operation, such as zero divide or an operation
SIGILL detection of an invalid function image, such as an invalid instruction
SIGINT receipt of an interactive attention signal
SIGSEGV an invalid access to storage
SIGILL detection of an invalid function image, such as an invalid instruction
SIGINT receipt of an interactive attention signal
SIGSEGV an invalid access to storage
An implementation need not generate any of these signals, except as a result of explicit
calls to the raise function. Additional signals and pointers to undeclarable functions,
with macro definitions beginning, respectively, with the letters SIG and an uppercase
An implementation need not generate any of these signals, except as a result of explicit
calls to the raise function. Additional signals and pointers to undeclarable functions,
with macro definitions beginning, respectively, with the letters SIG and an uppercase
<p><small><a name="note219" href="#note219">219)</a> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>). The names of the signal numbers reflect the following terms
(respectively): abort, floating-point exception, illegal instruction, interrupt, segmentation violation,
and termination.
<p><small><a name="note219" href="#note219">219)</a> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>). The names of the signal numbers reflect the following terms
(respectively): abort, floating-point exception, illegal instruction, interrupt, segmentation violation,
and termination.
<h4><a name="7.14.1" href="#7.14.1">7.14.1 Specify signal handling</a></h4>
<h5><a name="7.14.1.1" href="#7.14.1.1">7.14.1.1 The signal function</a></h5>
<h4><a name="7.14.1" href="#7.14.1">7.14.1 Specify signal handling</a></h4>
<h5><a name="7.14.1.1" href="#7.14.1.1">7.14.1.1 The signal function</a></h5>
<p><!--para 2 -->
The signal function chooses one of three ways in which receipt of the signal number
sig is to be subsequently handled. If the value of func is SIG_DFL, default handling
<p><!--para 2 -->
The signal function chooses one of three ways in which receipt of the signal number
sig is to be subsequently handled. If the value of func is SIG_DFL, default handling
is executed for all other signals defined by the implementation.
<p><!--para 7 -->
The implementation shall behave as if no library function calls the signal function.
is executed for all other signals defined by the implementation.
<p><!--para 7 -->
The implementation shall behave as if no library function calls the signal function.
<p><!--para 8 -->
If the request can be honored, the signal function returns the value of func for the
most recent successful call to signal for the specified signal sig. Otherwise, a value of
<p><!--para 8 -->
If the request can be honored, the signal function returns the value of func for the
most recent successful call to signal for the specified signal sig. Otherwise, a value of
<p><b> Forward references</b>: the abort function (<a href="#7.20.4.1">7.20.4.1</a>), the exit function (<a href="#7.20.4.3">7.20.4.3</a>), the
_Exit function (<a href="#7.20.4.4">7.20.4.4</a>).
<p><b> Forward references</b>: the abort function (<a href="#7.20.4.1">7.20.4.1</a>), the exit function (<a href="#7.20.4.3">7.20.4.3</a>), the
_Exit function (<a href="#7.20.4.4">7.20.4.4</a>).
<p><small><a name="note220" href="#note220">220)</a> If any signal is generated by an asynchronous signal handler, the behavior is undefined.
</small>
<h4><a name="7.14.2" href="#7.14.2">7.14.2 Send signal</a></h4>
<h5><a name="7.14.2.1" href="#7.14.2.1">7.14.2.1 The raise function</a></h5>
<p><small><a name="note220" href="#note220">220)</a> If any signal is generated by an asynchronous signal handler, the behavior is undefined.
</small>
<h4><a name="7.14.2" href="#7.14.2">7.14.2 Send signal</a></h4>
<h5><a name="7.14.2.1" href="#7.14.2.1">7.14.2.1 The raise function</a></h5>
<p><!--para 2 -->
The raise function carries out the actions described in <a href="#7.14.1.1">7.14.1.1</a> for the signal sig. If a
signal handler is called, the raise function shall not return until after the signal handler
does.
<p><!--para 2 -->
The raise function carries out the actions described in <a href="#7.14.1.1">7.14.1.1</a> for the signal sig. If a
signal handler is called, the raise function shall not return until after the signal handler
does.
<p><!--para 1 -->
The header <a href="#7.15"><stdarg.h></a> 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
<p><!--para 1 -->
The header <a href="#7.15"><stdarg.h></a> 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
which is an object type suitable for holding information needed by the macros
va_start, va_arg, va_end, and va_copy. If access to the varying arguments is
desired, the called function shall declare an object (generally referred to as ap in this
which is an object type suitable for holding information needed by the macros
va_start, va_arg, va_end, and va_copy. If access to the varying arguments is
desired, the called function shall declare an object (generally referred to as ap in this
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.<sup><a href="#note221"><b>221)</b></a></sup>
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.<sup><a href="#note221"><b>221)</b></a></sup>
<p><small><a name="note221" href="#note221">221)</a> 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.
</small>
<p><small><a name="note221" href="#note221">221)</a> 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.
</small>
<p><!--para 2 -->
The va_arg macro expands to an expression that has the specified type and the value of
the next argument in the call. The parameter ap shall have been initialized by the
<p><!--para 2 -->
The va_arg macro expands to an expression that has the specified type and the value of
the next argument in the call. The parameter ap shall have been initialized by the
type, and the value is representable in both types;
<li> one type is pointer to void and the other is a pointer to a character type.
</ul>
type, and the value is representable in both types;
<li> one type is pointer to void and the other is a pointer to a character type.
</ul>
<p><!--para 3 -->
The first invocation of the va_arg macro after that of the va_start macro returns the
value of the argument after that specified by parmN . Successive invocations return the
values of the remaining arguments in succession.
<h5><a name="7.15.1.2" href="#7.15.1.2">7.15.1.2 The va_copy macro</a></h5>
<p><!--para 3 -->
The first invocation of the va_arg macro after that of the va_start macro returns the
value of the argument after that specified by parmN . Successive invocations return the
values of the remaining arguments in succession.
<h5><a name="7.15.1.2" href="#7.15.1.2">7.15.1.2 The va_copy macro</a></h5>
<p><!--para 2 -->
The va_copy macro initializes dest as a copy of src, as if the va_start macro had
been applied to dest followed by the same sequence of uses of the va_arg macro as
had previously been used to reach the present state of src. Neither the va_copy nor
va_start macro shall be invoked to reinitialize dest without an intervening
invocation of the va_end macro for the same dest.
<p><!--para 2 -->
The va_copy macro initializes dest as a copy of src, as if the va_start macro had
been applied to dest followed by the same sequence of uses of the va_arg macro as
had previously been used to reach the present state of src. Neither the va_copy nor
va_start macro shall be invoked to reinitialize dest without an intervening
invocation of the va_end macro for the same dest.
<p><!--para 3 -->
The va_copy macro returns no value.
<h5><a name="7.15.1.3" href="#7.15.1.3">7.15.1.3 The va_end macro</a></h5>
<p><!--para 3 -->
The va_copy macro returns no value.
<h5><a name="7.15.1.3" href="#7.15.1.3">7.15.1.3 The va_end macro</a></h5>
<p><!--para 2 -->
The va_end macro facilitates a normal return from the function whose variable
argument list was referred to by the expansion of the va_start macro, or the function
<p><!--para 2 -->
The va_end macro facilitates a normal return from the function whose variable
argument list was referred to by the expansion of the va_start macro, or the function
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.
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.
<p><!--para 3 -->
The va_end macro returns no value.
<h5><a name="7.15.1.4" href="#7.15.1.4">7.15.1.4 The va_start macro</a></h5>
<p><!--para 3 -->
The va_end macro returns no value.
<h5><a name="7.15.1.4" href="#7.15.1.4">7.15.1.4 The va_start macro</a></h5>
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.
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.
which expands to the integer constant 1.
<p><!--para 4 -->
Notwithstanding the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and perhaps then
which expands to the integer constant 1.
<p><!--para 4 -->
Notwithstanding the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and perhaps then
<p><!--para 1 -->
The following types and macros are defined in the standard header <a href="#7.17"><stddef.h></a>. Some
are also defined in other headers, as noted in their respective subclauses.
<p><!--para 2 -->
The types are
<pre>
<p><!--para 1 -->
The following types and macros are defined in the standard header <a href="#7.17"><stddef.h></a>. Some
are also defined in other headers, as noted in their respective subclauses.
<p><!--para 2 -->
The types are
<pre>
which is an integer type whose range of values can represent distinct codes for all
members of the largest extended character set specified among the supported locales; the
null character shall have the code value zero. Each member of the basic character set
which is an integer type whose range of values can represent distinct codes for all
members of the largest extended character set specified among the supported locales; the
null character shall have the code value zero. Each member of the basic character set
which expands to an integer constant expression that has type size_t, the value of
which is the offset in bytes, to the structure member (designated by member-designator),
from the beginning of its structure (designated by type). The type and member designator
shall be such that given
<pre>
which expands to an integer constant expression that has type size_t, the value of
which is the offset in bytes, to the structure member (designated by member-designator),
from the beginning of its structure (designated by type). The type and member designator
shall be such that given
<pre>
then the expression &(t.member-designator) evaluates to an address constant. (If the
specified member is a bit-field, the behavior is undefined.)
then the expression &(t.member-designator) evaluates to an address constant. (If the
specified member is a bit-field, the behavior is undefined.)
<p><!--para 4 -->
The types used for size_t and ptrdiff_t should not have an integer conversion rank
greater than that of signed long int unless the implementation supports objects
<p><!--para 4 -->
The types used for size_t and ptrdiff_t should not have an integer conversion rank
greater than that of signed long int unless the implementation supports objects
<p><!--para 1 -->
The header <a href="#7.18"><stdint.h></a> declares sets of integer types having specified widths, and
defines corresponding sets of macros.<sup><a href="#note223"><b>223)</b></a></sup> It also defines macros that specify limits of
<p><!--para 1 -->
The header <a href="#7.18"><stdint.h></a> declares sets of integer types having specified widths, and
defines corresponding sets of macros.<sup><a href="#note223"><b>223)</b></a></sup> It also defines macros that specify limits of
shall provide those types described as ''required'', but need not provide any of the others
(described as ''optional'').
shall provide those types described as ''required'', but need not provide any of the others
(described as ''optional'').
<p><small><a name="note223" href="#note223">223)</a> See ''future library directions'' (<a href="#7.26.8">7.26.8</a>).
</small>
<p><small><a name="note224" href="#note224">224)</a> Some of these types may denote implementation-defined extended integer types.
<p><small><a name="note223" href="#note223">223)</a> See ''future library directions'' (<a href="#7.26.8">7.26.8</a>).
</small>
<p><small><a name="note224" href="#note224">224)</a> Some of these types may denote implementation-defined extended integer types.
int_least8_t uint_least8_t
int_least16_t uint_least16_t
int_least32_t uint_least32_t
int_least8_t uint_least8_t
int_least16_t uint_least16_t
int_least32_t uint_least32_t
All other types of this form are optional.
<h5><a name="7.18.1.3" href="#7.18.1.3">7.18.1.3 Fastest minimum-width integer types</a></h5>
All other types of this form are optional.
<h5><a name="7.18.1.3" href="#7.18.1.3">7.18.1.3 Fastest minimum-width integer types</a></h5>
<p><small><a name="note225" href="#note225">225)</a> 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.
<p><small><a name="note225" href="#note225">225)</a> 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.
pointer to void can be converted to this type, then converted back to pointer to void,
and the result will compare equal to the original pointer:
<pre>
pointer to void can be converted to this type, then converted back to pointer to void,
and the result will compare equal to the original pointer:
<pre>
The following type designates an unsigned integer type with the property that any valid
pointer to void can be converted to this type, then converted back to pointer to void,
and the result will compare equal to the original pointer:
<pre>
The following type designates an unsigned integer type with the property that any valid
pointer to void can be converted to this type, then converted back to pointer to void,
and the result will compare equal to the original pointer:
<pre>
These types are optional.
<h5><a name="7.18.1.5" href="#7.18.1.5">7.18.1.5 Greatest-width integer types</a></h5>
These types are optional.
<h5><a name="7.18.1.5" href="#7.18.1.5">7.18.1.5 Greatest-width integer types</a></h5>
The following type designates an unsigned integer type capable of representing any value
of any unsigned integer type:
<pre>
The following type designates an unsigned integer type capable of representing any value
of any unsigned integer type:
<pre>
These types are required.
<h4><a name="7.18.2" href="#7.18.2">7.18.2 Limits of specified-width integer types</a></h4>
These types are required.
<h4><a name="7.18.2" href="#7.18.2">7.18.2 Limits of specified-width integer types</a></h4>
magnitude (absolute value) than the corresponding value given below, with the same sign,
except where stated to be exactly the given value.
magnitude (absolute value) than the corresponding value given below, with the same sign,
except where stated to be exactly the given value.
<p><small><a name="note226" href="#note226">226)</a> C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
before <a href="#7.18"><stdint.h></a> is included.
</small>
<p><small><a name="note226" href="#note226">226)</a> C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
before <a href="#7.18"><stdint.h></a> is included.
</small>
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.
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.
<p><small><a name="note227" href="#note227">227)</a> C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
before <a href="#7.18"><stdint.h></a> is included.
</small>
<p><small><a name="note227" href="#note227">227)</a> C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
before <a href="#7.18"><stdint.h></a> is included.
</small>
<p><small><a name="note230" href="#note230">230)</a> C++ implementations should define these macros only when __STDC_CONSTANT_MACROS is
defined before <a href="#7.18"><stdint.h></a> is included.
</small>
<p><small><a name="note230" href="#note230">230)</a> C++ implementations should define these macros only when __STDC_CONSTANT_MACROS is
defined before <a href="#7.18"><stdint.h></a> is included.
</small>
The following macro expands to an integer constant expression having the value specified
by its argument and the type intmax_t:
<pre>
The following macro expands to an integer constant expression having the value specified
by its argument and the type intmax_t:
<pre>
The following macro expands to an integer constant expression having the value specified
by its argument and the type uintmax_t:
<!--page 274 -->
<pre>
The following macro expands to an integer constant expression having the value specified
by its argument and the type uintmax_t:
<!--page 274 -->
<pre>
which is an object type capable of recording all the information needed to control a
stream, including its file position indicator, a pointer to its associated buffer (if any), an
error indicator that records whether a read/write error has occurred, and an end-of-file
indicator that records whether the end of the file has been reached; and
<pre>
which is an object type capable of recording all the information needed to control a
stream, including its file position indicator, a pointer to its associated buffer (if any), an
error indicator that records whether a read/write error has occurred, and an end-of-file
indicator that records whether the end of the file has been reached; and
<pre>
which is an object type other than an array type capable of recording all the information
needed to specify uniquely every position within a file.
<p><!--para 3 -->
which is an object type other than an array type capable of recording all the information
needed to specify uniquely every position within a file.
<p><!--para 3 -->
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the setvbuf function;
<pre>
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the setvbuf function;
<pre>
which expands to an integer constant expression, with type int and a negative value, that
is returned by several functions to indicate end-of-file, that is, no more input from a
stream;
<pre>
which expands to an integer constant expression, with type int and a negative value, that
is returned by several functions to indicate end-of-file, that is, no more input from a
stream;
<pre>
which expands to an integer constant expression that is the minimum number of files that
the implementation guarantees can be open simultaneously;
<pre>
which expands to an integer constant expression that is the minimum number of files that
the implementation guarantees can be open simultaneously;
<pre>
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold the longest file name string that the implementation
<!--page 275 -->
guarantees can be opened;<sup><a href="#note231"><b>231)</b></a></sup>
<pre>
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold the longest file name string that the implementation
<!--page 275 -->
guarantees can be opened;<sup><a href="#note231"><b>231)</b></a></sup>
<pre>
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold a temporary file name string generated by the tmpnam
function;
<pre>
SEEK_CUR
SEEK_END
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold a temporary file name string generated by the tmpnam
function;
<pre>
SEEK_CUR
SEEK_END
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the fseek function;
<pre>
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the fseek function;
<pre>
which expands to an integer constant expression that is the maximum number of unique
file names that can be generated by the tmpnam function;
<pre>
stderr
stdin
which expands to an integer constant expression that is the maximum number of unique
file names that can be generated by the tmpnam function;
<pre>
stderr
stdin
which are expressions of type ''pointer to FILE'' that point to the FILE objects
associated, respectively, with the standard error, input, and output streams.
<p><!--para 4 -->
which are expressions of type ''pointer to FILE'' that point to the FILE objects
associated, respectively, with the standard error, input, and output streams.
<p><!--para 4 -->
<p><b> Forward references</b>: files (<a href="#7.19.3">7.19.3</a>), the fseek function (<a href="#7.19.9.2">7.19.9.2</a>), streams (<a href="#7.19.2">7.19.2</a>), the
tmpnam function (<a href="#7.19.4.4">7.19.4.4</a>), <a href="#7.24"><wchar.h></a> (<a href="#7.24">7.24</a>).
<p><b> Forward references</b>: files (<a href="#7.19.3">7.19.3</a>), the fseek function (<a href="#7.19.9.2">7.19.9.2</a>), streams (<a href="#7.19.2">7.19.2</a>), the
tmpnam function (<a href="#7.19.4.4">7.19.4.4</a>), <a href="#7.24"><wchar.h></a> (<a href="#7.24">7.24</a>).
<p><small><a name="note231" href="#note231">231)</a> 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
<p><small><a name="note231" href="#note231">231)</a> 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
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.
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.
<p><!--para 7 -->
An implementation shall support text files with lines containing at least 254 characters,
including the terminating new-line character. The value of the macro BUFSIZ shall be at
<p><!--para 7 -->
An implementation shall support text files with lines containing at least 254 characters,
including the terminating new-line character. The value of the macro BUFSIZ shall be at
<p><small><a name="note232" href="#note232">232)</a> 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.
<p><small><a name="note232" href="#note232">232)</a> 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.
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.
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.
fputwc function (<a href="#7.24.3.3">7.24.3.3</a>), conversion state (<a href="#7.24.6">7.24.6</a>), the mbrtowc function
(<a href="#7.24.6.3.2">7.24.6.3.2</a>), the wcrtomb function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
fputwc function (<a href="#7.24.3.3">7.24.3.3</a>), conversion state (<a href="#7.24.6">7.24.6</a>), the mbrtowc function
(<a href="#7.24.6.3.2">7.24.6.3.2</a>), the wcrtomb function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
<p><small><a name="note234" href="#note234">234)</a> 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.
<p><small><a name="note234" href="#note234">234)</a> 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.
<h4><a name="7.19.4" href="#7.19.4">7.19.4 Operations on files</a></h4>
<h5><a name="7.19.4.1" href="#7.19.4.1">7.19.4.1 The remove function</a></h5>
<h4><a name="7.19.4" href="#7.19.4">7.19.4 Operations on files</a></h4>
<h5><a name="7.19.4.1" href="#7.19.4.1">7.19.4.1 The remove function</a></h5>
<p><!--para 2 -->
The remove function causes the file whose name is the string pointed to by filename
to be no longer accessible by that name. A subsequent attempt to open that file using that
name will fail, unless it is created anew. If the file is open, the behavior of the remove
function is implementation-defined.
<p><!--para 2 -->
The remove function causes the file whose name is the string pointed to by filename
to be no longer accessible by that name. A subsequent attempt to open that file using that
name will fail, unless it is created anew. If the file is open, the behavior of the remove
function is implementation-defined.
<p><!--para 3 -->
The remove function returns zero if the operation succeeds, nonzero if it fails.
<h5><a name="7.19.4.2" href="#7.19.4.2">7.19.4.2 The rename function</a></h5>
<p><!--para 3 -->
The remove function returns zero if the operation succeeds, nonzero if it fails.
<h5><a name="7.19.4.2" href="#7.19.4.2">7.19.4.2 The rename function</a></h5>
<p><!--para 2 -->
The rename function causes the file whose name is the string pointed to by old to be
henceforth known by the name given by the string pointed to by new. The file named
old is no longer accessible by that name. If a file named by the string pointed to by new
exists prior to the call to the rename function, the behavior is implementation-defined.
<!--page 281 -->
<p><!--para 2 -->
The rename function causes the file whose name is the string pointed to by old to be
henceforth known by the name given by the string pointed to by new. The file named
old is no longer accessible by that name. If a file named by the string pointed to by new
exists prior to the call to the rename function, the behavior is implementation-defined.
<!--page 281 -->
<p><!--para 3 -->
The rename function returns zero if the operation succeeds, nonzero if it fails,<sup><a href="#note235"><b>235)</b></a></sup> in
which case if the file existed previously it is still known by its original name.
<p><!--para 3 -->
The rename function returns zero if the operation succeeds, nonzero if it fails,<sup><a href="#note235"><b>235)</b></a></sup> in
which case if the file existed previously it is still known by its original name.
<p><small><a name="note235" href="#note235">235)</a> 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.
</small>
<h5><a name="7.19.4.3" href="#7.19.4.3">7.19.4.3 The tmpfile function</a></h5>
<p><small><a name="note235" href="#note235">235)</a> 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.
</small>
<h5><a name="7.19.4.3" href="#7.19.4.3">7.19.4.3 The tmpfile function</a></h5>
<p><!--para 2 -->
The tmpfile function creates a temporary binary file that is different from any other
existing file and that will automatically be removed when it is closed or at program
termination. If the program terminates abnormally, whether an open temporary file is
removed is implementation-defined. The file is opened for update with "wb+" mode.
<p><!--para 2 -->
The tmpfile function creates a temporary binary file that is different from any other
existing file and that will automatically be removed when it is closed or at program
termination. If the program terminates abnormally, whether an open temporary file is
removed is implementation-defined. The file is opened for update with "wb+" mode.
<p><!--para 3 -->
It should be possible to open at least TMP_MAX temporary files during the lifetime of the
program (this limit may be shared with tmpnam) and there should be no limit on the
number simultaneously open other than this limit and any limit on the number of open
files (FOPEN_MAX).
<p><!--para 3 -->
It should be possible to open at least TMP_MAX temporary files during the lifetime of the
program (this limit may be shared with tmpnam) and there should be no limit on the
number simultaneously open other than this limit and any limit on the number of open
files (FOPEN_MAX).
<p><!--para 4 -->
The tmpfile function returns a pointer to the stream of the file that it created. If the file
cannot be created, the tmpfile function returns a null pointer.
<p><b> Forward references</b>: the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<h5><a name="7.19.4.4" href="#7.19.4.4">7.19.4.4 The tmpnam function</a></h5>
<p><!--para 4 -->
The tmpfile function returns a pointer to the stream of the file that it created. If the file
cannot be created, the tmpfile function returns a null pointer.
<p><b> Forward references</b>: the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<h5><a name="7.19.4.4" href="#7.19.4.4">7.19.4.4 The tmpnam function</a></h5>
<p><!--para 2 -->
The tmpnam function generates a string that is a valid file name and that is not the same
as the name of an existing file.<sup><a href="#note236"><b>236)</b></a></sup> The function is potentially capable of generating
<p><!--para 2 -->
The tmpnam function generates a string that is a valid file name and that is not the same
as the name of an existing file.<sup><a href="#note236"><b>236)</b></a></sup> The function is potentially capable of generating
The tmpnam function generates a different string each time it is called.
<p><!--para 4 -->
The implementation shall behave as if no library function calls the tmpnam function.
The tmpnam function generates a different string each time it is called.
<p><!--para 4 -->
The implementation shall behave as if no library function calls the tmpnam function.
<p><!--para 5 -->
If no suitable string can be generated, the tmpnam function returns a null pointer.
Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an
<p><!--para 5 -->
If no suitable string can be generated, the tmpnam function returns a null pointer.
Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an
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.
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.
<p><small><a name="note236" href="#note236">236)</a> 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
<p><small><a name="note236" href="#note236">236)</a> 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
<h4><a name="7.19.5" href="#7.19.5">7.19.5 File access functions</a></h4>
<h5><a name="7.19.5.1" href="#7.19.5.1">7.19.5.1 The fclose function</a></h5>
<h4><a name="7.19.5" href="#7.19.5">7.19.5 File access functions</a></h4>
<h5><a name="7.19.5.1" href="#7.19.5.1">7.19.5.1 The fclose function</a></h5>
<p><!--para 2 -->
A successful call to the fclose function causes the stream pointed to by stream to be
flushed and the associated file to be closed. Any unwritten buffered data for the stream
<p><!--para 2 -->
A successful call to the fclose function causes the stream pointed to by stream to be
flushed and the associated file to be closed. Any unwritten buffered data for the stream
are 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).
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).
<p><!--para 3 -->
The fclose function returns zero if the stream was successfully closed, or EOF if any
errors were detected.
<h5><a name="7.19.5.2" href="#7.19.5.2">7.19.5.2 The fflush function</a></h5>
<p><!--para 3 -->
The fclose function returns zero if the stream was successfully closed, or EOF if any
errors were detected.
<h5><a name="7.19.5.2" href="#7.19.5.2">7.19.5.2 The fflush function</a></h5>
<p><!--para 2 -->
If stream points to an output stream or an update stream in which the most recent
operation was not input, the fflush function causes any unwritten data for that stream
<p><!--para 2 -->
If stream points to an output stream or an update stream in which the most recent
operation was not input, the fflush function causes any unwritten data for that stream
<p><!--para 3 -->
If stream is a null pointer, the fflush function performs this flushing action on all
streams for which the behavior is defined above.
<p><!--para 3 -->
If stream is a null pointer, the fflush function performs this flushing action on all
streams for which the behavior is defined above.
<p><!--para 4 -->
The fflush function sets the error indicator for the stream and returns EOF if a write
error occurs, otherwise it returns zero.
<p><b> Forward references</b>: the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<h5><a name="7.19.5.3" href="#7.19.5.3">7.19.5.3 The fopen function</a></h5>
<p><!--para 4 -->
The fflush function sets the error indicator for the stream and returns EOF if a write
error occurs, otherwise it returns zero.
<p><b> Forward references</b>: the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<h5><a name="7.19.5.3" href="#7.19.5.3">7.19.5.3 The fopen function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *fopen(const char * restrict filename,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *fopen(const char * restrict filename,
<p><!--para 2 -->
The fopen function opens the file whose name is the string pointed to by filename,
and associates a stream with it.
<p><!--para 2 -->
The fopen function opens the file whose name is the string pointed to by filename,
and associates a stream with it.
<p><!--para 7 -->
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.
<p><!--para 7 -->
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.
<p><!--para 8 -->
The fopen function returns a pointer to the object controlling the stream. If the open
operation fails, fopen returns a null pointer.
<p><b> Forward references</b>: file positioning functions (<a href="#7.19.9">7.19.9</a>).
<p><!--para 8 -->
The fopen function returns a pointer to the object controlling the stream. If the open
operation fails, fopen returns a null pointer.
<p><b> Forward references</b>: file positioning functions (<a href="#7.19.9">7.19.9</a>).
<p><small><a name="note237" href="#note237">237)</a> 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 <a href="#7.19.2">7.19.2</a>).
</small>
<h5><a name="7.19.5.4" href="#7.19.5.4">7.19.5.4 The freopen function</a></h5>
<p><small><a name="note237" href="#note237">237)</a> 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 <a href="#7.19.2">7.19.2</a>).
</small>
<h5><a name="7.19.5.4" href="#7.19.5.4">7.19.5.4 The freopen function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *freopen(const char * restrict filename,
const char * restrict mode,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *freopen(const char * restrict filename,
const char * restrict mode,
<p><!--para 2 -->
The freopen function opens the file whose name is the string pointed to by filename
and associates the stream pointed to by stream with it. The mode argument is used just
<p><!--para 2 -->
The freopen function opens the file whose name is the string pointed to by filename
and associates the stream pointed to by stream with it. The mode argument is used just
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.
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.
<p><!--para 5 -->
The freopen function returns a null pointer if the open operation fails. Otherwise,
freopen returns the value of stream.
<p><!--para 5 -->
The freopen function returns a null pointer if the open operation fails. Otherwise,
freopen returns the value of stream.
<p><small><a name="note238" href="#note238">238)</a> 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.
</small>
<h5><a name="7.19.5.5" href="#7.19.5.5">7.19.5.5 The setbuf function</a></h5>
<p><small><a name="note238" href="#note238">238)</a> 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.
</small>
<h5><a name="7.19.5.5" href="#7.19.5.5">7.19.5.5 The setbuf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void setbuf(FILE * restrict stream,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void setbuf(FILE * restrict stream,
<p><!--para 2 -->
Except that it returns no value, the setbuf function is equivalent to the setvbuf
function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf
is a null pointer), with the value _IONBF for mode.
<p><!--para 2 -->
Except that it returns no value, the setbuf function is equivalent to the setvbuf
function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf
is a null pointer), with the value _IONBF for mode.
<p><!--para 3 -->
The setbuf function returns no value.
<p><b> Forward references</b>: the setvbuf function (<a href="#7.19.5.6">7.19.5.6</a>).
<h5><a name="7.19.5.6" href="#7.19.5.6">7.19.5.6 The setvbuf function</a></h5>
<p><!--para 3 -->
The setbuf function returns no value.
<p><b> Forward references</b>: the setvbuf function (<a href="#7.19.5.6">7.19.5.6</a>).
<h5><a name="7.19.5.6" href="#7.19.5.6">7.19.5.6 The setvbuf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int setvbuf(FILE * restrict stream,
char * restrict buf,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int setvbuf(FILE * restrict stream,
char * restrict buf,
<p><!--para 2 -->
The setvbuf function may be used only after the stream pointed to by stream has
been associated with an open file and before any other operation (other than an
<p><!--para 2 -->
The setvbuf function may be used only after the stream pointed to by stream has
been associated with an open file and before any other operation (other than an
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.
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.
<p><!--para 3 -->
The setvbuf function returns zero on success, or nonzero if an invalid value is given
for mode or if the request cannot be honored.
<p><!--para 3 -->
The setvbuf function returns zero on success, or nonzero if an invalid value is given
for mode or if the request cannot be honored.
<p><small><a name="note239" href="#note239">239)</a> 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.
</small>
<p><small><a name="note239" href="#note239">239)</a> 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.
</small>
The formatted input/output functions shall behave as if there is a sequence point after the
actions associated with each specifier.<sup><a href="#note240"><b>240)</b></a></sup>
The formatted input/output functions shall behave as if there is a sequence point after the
actions associated with each specifier.<sup><a href="#note240"><b>240)</b></a></sup>
<p><small><a name="note240" href="#note240">240)</a> The fprintf functions perform writes to memory for the %n specifier.
</small>
<h5><a name="7.19.6.1" href="#7.19.6.1">7.19.6.1 The fprintf function</a></h5>
<p><small><a name="note240" href="#note240">240)</a> The fprintf functions perform writes to memory for the %n specifier.
</small>
<h5><a name="7.19.6.1" href="#7.19.6.1">7.19.6.1 The fprintf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fprintf(FILE * restrict stream,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fprintf(FILE * restrict stream,
<p><!--para 2 -->
The fprintf function writes output to the stream pointed to by stream, under control
of the string pointed to by format that specifies how subsequent arguments are
<p><!--para 2 -->
The fprintf function writes output to the stream pointed to by stream, under control
of the string pointed to by format that specifies how subsequent arguments are
<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
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.
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.
<p><!--para 14 -->
The fprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
<p><!--para 14 -->
The fprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
int day, hour, min;
fprintf(stdout, "%s, %s %d, %.2d:%.2d\n",
weekday, month, day, hour, min);
int day, hour, min;
fprintf(stdout, "%s, %s %d, %.2d:%.2d\n",
weekday, month, day, hour, min);
fprintf(stdout, "|%13.10ls|\n", wstr);
fprintf(stdout, "|%13.11ls|\n", wstr);
fprintf(stdout, "|%13.15ls|\n", &wstr[2]);
fprintf(stdout, "|%13.10ls|\n", wstr);
fprintf(stdout, "|%13.11ls|\n", wstr);
fprintf(stdout, "|%13.15ls|\n", &wstr[2]);
<p><small><a name="note241" href="#note241">241)</a> Note that 0 is taken as a flag, not as the beginning of a field width.
</small>
<p><small><a name="note242" href="#note242">242)</a> The results of all floating conversions of a negative zero, and of negative values that round to zero,
<p><small><a name="note241" href="#note241">241)</a> Note that 0 is taken as a flag, not as the beginning of a field width.
</small>
<p><small><a name="note242" href="#note242">242)</a> The results of all floating conversions of a negative zero, and of negative values that round to zero,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fscanf(FILE * restrict stream,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fscanf(FILE * restrict stream,
<p><!--para 2 -->
The fscanf function reads input from the stream pointed to by stream, under control
of the string pointed to by format that specifies the admissible input sequences and how
<p><!--para 2 -->
The fscanf function reads input from the stream pointed to by stream, under control
of the string pointed to by format that specifies the admissible input sequences and how
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.
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.
<p><!--para 16 -->
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
<p><!--para 16 -->
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
#include <a href="#7.19"><stdio.h></a>
/* ... */
int n, i; float x; char name[50];
#include <a href="#7.19"><stdio.h></a>
/* ... */
int n, i; float x; char name[50];
- n = fscanf(stdin, "%d%f%s", &i, &x, name);</pre>
+ n = fscanf(stdin, "%d%f%s", &i, &x, name);
+</pre>
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
- fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name);</pre>
+ fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name);
+</pre>
will assign to i the value 56 and to x the value 789.0, will skip 0123, and will assign to name the
sequence 56\0. The next character read from the input stream will be a.
<p><!--para 19 -->
EXAMPLE 3 To accept repeatedly from stdin a quantity, a unit of measure, and an item name:
will assign to i the value 56 and to x the value 789.0, will skip 0123, and will assign to name the
sequence 56\0. The next character read from the input stream will be a.
<p><!--para 19 -->
EXAMPLE 3 To accept repeatedly from stdin a quantity, a unit of measure, and an item name:
do {
count = fscanf(stdin, "%f%20s of %20s", &quant, units, item);
fscanf(stdin,"%*[^\n]");
do {
count = fscanf(stdin, "%f%20s of %20s", &quant, units, item);
fscanf(stdin,"%*[^\n]");
the execution of the above example will be analogous to the following assignments:
<pre>
quant = 2; strcpy(units, "quarts"); strcpy(item, "oil");
the execution of the above example will be analogous to the following assignments:
<pre>
quant = 2; strcpy(units, "quarts"); strcpy(item, "oil");
quant = 10.0; strcpy(units, "LBS"); strcpy(item, "dirt");
count = 3;
count = 0; // "100e" fails to match "%f"
quant = 10.0; strcpy(units, "LBS"); strcpy(item, "dirt");
count = 3;
count = 0; // "100e" fails to match "%f"
- i = sscanf("123", "%d%n%n%d", &d1, &n1, &n2, &d2);</pre>
+ i = sscanf("123", "%d%n%n%d", &d1, &n1, &n2, &d2);
+</pre>
the value 123 is assigned to d1 and the value 3 to n1. Because %n can never get an input failure the value
of 3 is also assigned to n2. The value of d2 is not affected. The value 1 is assigned to i.
the value 123 is assigned to d1 and the value 3 to n1. Because %n can never get an input failure the value
of 3 is also assigned to n2. The value of d2 is not affected. The value 1 is assigned to i.
str will contain (uparrow) X Y(downarrow)\0 assuming that none of the bytes of the shift sequences (or of the multibyte
characters, in the more general case) appears to be a single-byte white-space character.
<p><!--para 24 -->
str will contain (uparrow) X Y(downarrow)\0 assuming that none of the bytes of the shift sequences (or of the multibyte
characters, in the more general case) appears to be a single-byte white-space character.
<p><!--para 24 -->
with the same input line, wstr will contain the two wide characters that correspond to X and Y and a
terminating null wide character.
<p><!--para 25 -->
with the same input line, wstr will contain the two wide characters that correspond to X and Y and a
terminating null wide character.
<p><!--para 25 -->
with the same input line, zero will again be returned, but stdin will be left with a partially consumed
multibyte character.
with the same input line, zero will again be returned, but stdin will be left with a partially consumed
multibyte character.
<p><small><a name="note250" href="#note250">250)</a> These white-space characters are not counted against a specified field width.
</small>
<p><small><a name="note251" href="#note251">251)</a> fscanf pushes back at most one input character onto the input stream. Therefore, some sequences
<p><small><a name="note250" href="#note250">250)</a> These white-space characters are not counted against a specified field width.
</small>
<p><small><a name="note251" href="#note251">251)</a> fscanf pushes back at most one input character onto the input stream. Therefore, some sequences
<p><!--para 2 -->
The printf function is equivalent to fprintf with the argument stdout interposed
before the arguments to printf.
<p><!--para 2 -->
The printf function is equivalent to fprintf with the argument stdout interposed
before the arguments to printf.
<p><!--para 3 -->
The printf function returns the number of characters transmitted, or a negative value if
an output or encoding error occurred.
<h5><a name="7.19.6.4" href="#7.19.6.4">7.19.6.4 The scanf function</a></h5>
<p><!--para 3 -->
The printf function returns the number of characters transmitted, or a negative value if
an output or encoding error occurred.
<h5><a name="7.19.6.4" href="#7.19.6.4">7.19.6.4 The scanf function</a></h5>
<p><!--para 2 -->
The scanf function is equivalent to fscanf with the argument stdin interposed
before the arguments to scanf.
<p><!--para 2 -->
The scanf function is equivalent to fscanf with the argument stdin interposed
before the arguments to scanf.
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int snprintf(char * restrict s, size_t n,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int snprintf(char * restrict s, size_t n,
<p><!--para 2 -->
The snprintf function is equivalent to fprintf, except that the output is written into
an array (specified by argument s) rather than to a stream. If n is zero, nothing is written,
<p><!--para 2 -->
The snprintf function is equivalent to fprintf, except that the output is written into
an array (specified by argument s) rather than to a stream. If n is zero, nothing is written,
of the characters actually written into the array. If copying takes place between objects
that overlap, the behavior is undefined.
<!--page 303 -->
of the characters actually written into the array. If copying takes place between objects
that overlap, the behavior is undefined.
<!--page 303 -->
<p><!--para 3 -->
The snprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
<p><!--para 3 -->
The snprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
completely written if and only if the returned value is nonnegative and less than n.
<h5><a name="7.19.6.6" href="#7.19.6.6">7.19.6.6 The sprintf function</a></h5>
completely written if and only if the returned value is nonnegative and less than n.
<h5><a name="7.19.6.6" href="#7.19.6.6">7.19.6.6 The sprintf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sprintf(char * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sprintf(char * restrict s,
<p><!--para 2 -->
The sprintf function is equivalent to fprintf, except that the output is written into
an array (specified by the argument s) rather than to a stream. A null character is written
at the end of the characters written; it is not counted as part of the returned value. If
copying takes place between objects that overlap, the behavior is undefined.
<p><!--para 2 -->
The sprintf function is equivalent to fprintf, except that the output is written into
an array (specified by the argument s) rather than to a stream. A null character is written
at the end of the characters written; it is not counted as part of the returned value. If
copying takes place between objects that overlap, the behavior is undefined.
<p><!--para 3 -->
The sprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<h5><a name="7.19.6.7" href="#7.19.6.7">7.19.6.7 The sscanf function</a></h5>
<p><!--para 3 -->
The sprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<h5><a name="7.19.6.7" href="#7.19.6.7">7.19.6.7 The sscanf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sscanf(const char * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sscanf(const char * restrict s,
<p><!--para 2 -->
The sscanf function is equivalent to fscanf, except that input is obtained from a
string (specified by the argument s) rather than from a stream. Reaching the end of the
string is equivalent to encountering end-of-file for the fscanf function. If copying
takes place between objects that overlap, the behavior is undefined.
<p><!--para 2 -->
The sscanf function is equivalent to fscanf, except that input is obtained from a
string (specified by the argument s) rather than from a stream. Reaching the end of the
string is equivalent to encountering end-of-file for the fscanf function. If copying
takes place between objects that overlap, the behavior is undefined.
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vfprintf(FILE * restrict stream,
const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vfprintf(FILE * restrict stream,
const char * restrict format,
<p><!--para 2 -->
The vfprintf function is equivalent to fprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 2 -->
The vfprintf function is equivalent to fprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 3 -->
The vfprintf function returns the number of characters transmitted, or a negative
value if an output or encoding error occurred.
<p><!--para 3 -->
The vfprintf function returns the number of characters transmitted, or a negative
value if an output or encoding error occurred.
// print out remainder of message
vfprintf(stderr, format, args);
va_end(args);
// print out remainder of message
vfprintf(stderr, format, args);
va_end(args);
<p><small><a name="note254" href="#note254">254)</a> 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.
</small>
<h5><a name="7.19.6.9" href="#7.19.6.9">7.19.6.9 The vfscanf function</a></h5>
<p><small><a name="note254" href="#note254">254)</a> 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.
</small>
<h5><a name="7.19.6.9" href="#7.19.6.9">7.19.6.9 The vfscanf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vfscanf(FILE * restrict stream,
const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vfscanf(FILE * restrict stream,
const char * restrict format,
<p><!--para 2 -->
The vfscanf function is equivalent to fscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfscanf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 2 -->
The vfscanf function is equivalent to fscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfscanf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vprintf(const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vprintf(const char * restrict format,
<p><!--para 2 -->
The vprintf function is equivalent to printf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 2 -->
The vprintf function is equivalent to printf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 3 -->
The vprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
<!--page 306 -->
<h5><a name="7.19.6.11" href="#7.19.6.11">7.19.6.11 The vscanf function</a></h5>
<p><!--para 3 -->
The vprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
<!--page 306 -->
<h5><a name="7.19.6.11" href="#7.19.6.11">7.19.6.11 The vscanf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vscanf(const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vscanf(const char * restrict format,
<p><!--para 2 -->
The vscanf function is equivalent to scanf, with the variable argument list replaced
by arg, which shall have been initialized by the va_start macro (and possibly
subsequent va_arg calls). The vscanf function does not invoke the va_end
macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 2 -->
The vscanf function is equivalent to scanf, with the variable argument list replaced
by arg, which shall have been initialized by the va_start macro (and possibly
subsequent va_arg calls). The vscanf function does not invoke the va_end
macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vsnprintf(char * restrict s, size_t n,
const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vsnprintf(char * restrict s, size_t n,
const char * restrict format,
<p><!--para 2 -->
The vsnprintf function is equivalent to snprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsnprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup> If copying takes place between objects that overlap, the behavior is
undefined.
<p><!--para 2 -->
The vsnprintf function is equivalent to snprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsnprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup> If copying takes place between objects that overlap, the behavior is
undefined.
<p><!--para 3 -->
The vsnprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
<p><!--para 3 -->
The vsnprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vsprintf(char * restrict s,
const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vsprintf(char * restrict s,
const char * restrict format,
<p><!--para 2 -->
The vsprintf function is equivalent to sprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup> If copying takes place between objects that overlap, the behavior is
undefined.
<p><!--para 2 -->
The vsprintf function is equivalent to sprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup> If copying takes place between objects that overlap, the behavior is
undefined.
<p><!--para 3 -->
The vsprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<h5><a name="7.19.6.14" href="#7.19.6.14">7.19.6.14 The vsscanf function</a></h5>
<p><!--para 3 -->
The vsprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<h5><a name="7.19.6.14" href="#7.19.6.14">7.19.6.14 The vsscanf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vsscanf(const char * restrict s,
const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vsscanf(const char * restrict s,
const char * restrict format,
<p><!--para 2 -->
The vsscanf function is equivalent to sscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsscanf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 2 -->
The vsscanf function is equivalent to sscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsscanf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<h4><a name="7.19.7" href="#7.19.7">7.19.7 Character input/output functions</a></h4>
<h5><a name="7.19.7.1" href="#7.19.7.1">7.19.7.1 The fgetc function</a></h5>
<h4><a name="7.19.7" href="#7.19.7">7.19.7 Character input/output functions</a></h4>
<h5><a name="7.19.7.1" href="#7.19.7.1">7.19.7.1 The fgetc function</a></h5>
<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next character is present, the fgetc function obtains that character as an unsigned
char converted to an int and advances the associated file position indicator for the
stream (if defined).
<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next character is present, the fgetc function obtains that character as an unsigned
char converted to an int and advances the associated file position indicator for the
stream (if defined).
<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
If a read error occurs, the error indicator for the stream is set and the fgetc function
returns EOF.<sup><a href="#note255"><b>255)</b></a></sup>
If a read error occurs, the error indicator for the stream is set and the fgetc function
returns EOF.<sup><a href="#note255"><b>255)</b></a></sup>
<p><small><a name="note255" href="#note255">255)</a> An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
</small>
<h5><a name="7.19.7.2" href="#7.19.7.2">7.19.7.2 The fgets function</a></h5>
<p><small><a name="note255" href="#note255">255)</a> An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
</small>
<h5><a name="7.19.7.2" href="#7.19.7.2">7.19.7.2 The fgets function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
char *fgets(char * restrict s, int n,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
char *fgets(char * restrict s, int n,
<p><!--para 2 -->
The fgets function reads at most one less than the number of characters specified by n
from the stream pointed to by stream into the array pointed to by s. No additional
characters are read after a new-line character (which is retained) or after end-of-file. A
null character is written immediately after the last character read into the array.
<p><!--para 2 -->
The fgets function reads at most one less than the number of characters specified by n
from the stream pointed to by stream into the array pointed to by s. No additional
characters are read after a new-line character (which is retained) or after end-of-file. A
null character is written immediately after the last character read into the array.
<p><!--para 3 -->
The fgets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
<p><!--para 3 -->
The fgets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
<p><!--para 2 -->
The fputc function writes the character specified by c (converted to an unsigned
char) to the output stream pointed to by stream, at the position indicated by the
associated file position indicator for the stream (if defined), and advances the indicator
appropriately. If the file cannot support positioning requests, or if the stream was opened
with append mode, the character is appended to the output stream.
<p><!--para 2 -->
The fputc function writes the character specified by c (converted to an unsigned
char) to the output stream pointed to by stream, at the position indicated by the
associated file position indicator for the stream (if defined), and advances the indicator
appropriately. If the file cannot support positioning requests, or if the stream was opened
with append mode, the character is appended to the output stream.
<p><!--para 3 -->
The fputc function returns the character written. If a write error occurs, the error
indicator for the stream is set and fputc returns EOF.
<h5><a name="7.19.7.4" href="#7.19.7.4">7.19.7.4 The fputs function</a></h5>
<p><!--para 3 -->
The fputc function returns the character written. If a write error occurs, the error
indicator for the stream is set and fputc returns EOF.
<h5><a name="7.19.7.4" href="#7.19.7.4">7.19.7.4 The fputs function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fputs(const char * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fputs(const char * restrict s,
<p><!--para 2 -->
The fputs function writes the string pointed to by s to the stream pointed to by
stream. The terminating null character is not written.
<p><!--para 2 -->
The fputs function writes the string pointed to by s to the stream pointed to by
stream. The terminating null character is not written.
<p><!--para 3 -->
The fputs function returns EOF if a write error occurs; otherwise it returns a
nonnegative value.
<h5><a name="7.19.7.5" href="#7.19.7.5">7.19.7.5 The getc function</a></h5>
<p><!--para 3 -->
The fputs function returns EOF if a write error occurs; otherwise it returns a
nonnegative value.
<h5><a name="7.19.7.5" href="#7.19.7.5">7.19.7.5 The getc function</a></h5>
<p><!--para 2 -->
The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
may evaluate stream more than once, so the argument should never be an expression
with side effects.
<!--page 310 -->
<p><!--para 2 -->
The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
may evaluate stream more than once, so the argument should never be an expression
with side effects.
<!--page 310 -->
<p><!--para 3 -->
The getc function returns the next character from the input stream pointed to by
stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
<p><!--para 3 -->
The getc function returns the next character from the input stream pointed to by
stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
<p><!--para 3 -->
The getchar function returns the next character from the input stream pointed to by
stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
<p><!--para 3 -->
The getchar function returns the next character from the input stream pointed to by
stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 2 -->
The putc function is equivalent to fputc, except that if it is implemented as a macro, it
may evaluate stream more than once, so that argument should never be an expression
with side effects.
<p><!--para 2 -->
The putc function is equivalent to fputc, except that if it is implemented as a macro, it
may evaluate stream more than once, so that argument should never be an expression
with side effects.
<p><!--para 3 -->
The putc function returns the character written. If a write error occurs, the error
indicator for the stream is set and putc returns EOF.
<h5><a name="7.19.7.9" href="#7.19.7.9">7.19.7.9 The putchar function</a></h5>
<p><!--para 3 -->
The putc function returns the character written. If a write error occurs, the error
indicator for the stream is set and putc returns EOF.
<h5><a name="7.19.7.9" href="#7.19.7.9">7.19.7.9 The putchar function</a></h5>
<p><!--para 3 -->
The putchar function returns the character written. If a write error occurs, the error
indicator for the stream is set and putchar returns EOF.
<h5><a name="7.19.7.10" href="#7.19.7.10">7.19.7.10 The puts function</a></h5>
<p><!--para 3 -->
The putchar function returns the character written. If a write error occurs, the error
indicator for the stream is set and putchar returns EOF.
<h5><a name="7.19.7.10" href="#7.19.7.10">7.19.7.10 The puts function</a></h5>
<p><!--para 2 -->
The puts function writes the string pointed to by s to the stream pointed to by stdout,
and appends a new-line character to the output. The terminating null character is not
written.
<p><!--para 2 -->
The puts function writes the string pointed to by s to the stream pointed to by stdout,
and appends a new-line character to the output. The terminating null character is not
written.
<p><!--para 3 -->
The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative
value.
<!--page 312 -->
<h5><a name="7.19.7.11" href="#7.19.7.11">7.19.7.11 The ungetc function</a></h5>
<p><!--para 3 -->
The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative
value.
<!--page 312 -->
<h5><a name="7.19.7.11" href="#7.19.7.11">7.19.7.11 The ungetc function</a></h5>
<p><!--para 2 -->
The ungetc function pushes the character specified by c (converted to an unsigned
char) back onto the input stream pointed to by stream. Pushed-back characters will be
<p><!--para 2 -->
The ungetc function pushes the character specified by c (converted to an unsigned
char) back onto the input stream pointed to by stream. Pushed-back characters will be
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.<sup><a href="#note256"><b>256)</b></a></sup>
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.<sup><a href="#note256"><b>256)</b></a></sup>
<p><small><a name="note256" href="#note256">256)</a> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
</small>
<h4><a name="7.19.8" href="#7.19.8">7.19.8 Direct input/output functions</a></h4>
<h5><a name="7.19.8.1" href="#7.19.8.1">7.19.8.1 The fread function</a></h5>
<p><small><a name="note256" href="#note256">256)</a> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
</small>
<h4><a name="7.19.8" href="#7.19.8">7.19.8 Direct input/output functions</a></h4>
<h5><a name="7.19.8.1" href="#7.19.8.1">7.19.8.1 The fread function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fread(void * restrict ptr,
size_t size, size_t nmemb,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fread(void * restrict ptr,
size_t size, size_t nmemb,
<p><!--para 2 -->
The fread function reads, into the array pointed to by ptr, up to nmemb elements
whose size is specified by size, from the stream pointed to by stream. For each
<p><!--para 2 -->
The fread function reads, into the array pointed to by ptr, up to nmemb elements
whose size is specified by size, from the stream pointed to by stream. For each
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.
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.
<p><!--para 3 -->
The fread function returns the number of elements successfully read, which may be
less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero,
<p><!--para 3 -->
The fread function returns the number of elements successfully read, which may be
less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fwrite(const void * restrict ptr,
size_t size, size_t nmemb,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fwrite(const void * restrict ptr,
size_t size, size_t nmemb,
<p><!--para 2 -->
The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
whose size is specified by size, to the stream pointed to by stream. For each object,
<p><!--para 2 -->
The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
whose size is specified by size, to the stream pointed to by stream. For each object,
<p><!--para 3 -->
The fwrite function returns the number of elements successfully written, which will be
less than nmemb only if a write error is encountered. If size or nmemb is zero,
<p><!--para 3 -->
The fwrite function returns the number of elements successfully written, which will be
less than nmemb only if a write error is encountered. If size or nmemb is zero,
<h4><a name="7.19.9" href="#7.19.9">7.19.9 File positioning functions</a></h4>
<h5><a name="7.19.9.1" href="#7.19.9.1">7.19.9.1 The fgetpos function</a></h5>
<h4><a name="7.19.9" href="#7.19.9">7.19.9 File positioning functions</a></h4>
<h5><a name="7.19.9.1" href="#7.19.9.1">7.19.9.1 The fgetpos function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fgetpos(FILE * restrict stream,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fgetpos(FILE * restrict stream,
<p><!--para 2 -->
The fgetpos function stores the current values of the parse state (if any) and file
position indicator for the stream pointed to by stream in the object pointed to by pos.
The values stored contain unspecified information usable by the fsetpos function for
repositioning the stream to its position at the time of the call to the fgetpos function.
<p><!--para 2 -->
The fgetpos function stores the current values of the parse state (if any) and file
position indicator for the stream pointed to by stream in the object pointed to by pos.
The values stored contain unspecified information usable by the fsetpos function for
repositioning the stream to its position at the time of the call to the fgetpos function.
<p><!--para 3 -->
If successful, the fgetpos function returns zero; on failure, the fgetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<p><b> Forward references</b>: the fsetpos function (<a href="#7.19.9.3">7.19.9.3</a>).
<h5><a name="7.19.9.2" href="#7.19.9.2">7.19.9.2 The fseek function</a></h5>
<p><!--para 3 -->
If successful, the fgetpos function returns zero; on failure, the fgetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<p><b> Forward references</b>: the fsetpos function (<a href="#7.19.9.3">7.19.9.3</a>).
<h5><a name="7.19.9.2" href="#7.19.9.2">7.19.9.2 The fseek function</a></h5>
<p><!--para 2 -->
The fseek function sets the file position indicator for the stream pointed to by stream.
If a read or write error occurs, the error indicator for the stream is set and fseek fails.
<p><!--para 2 -->
The fseek function sets the file position indicator for the stream pointed to by stream.
If a read or write error occurs, the error indicator for the stream is set and fseek fails.
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.
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.
<p><!--para 6 -->
The fseek function returns nonzero only for a request that cannot be satisfied.
<p><b> Forward references</b>: the ftell function (<a href="#7.19.9.4">7.19.9.4</a>).
<h5><a name="7.19.9.3" href="#7.19.9.3">7.19.9.3 The fsetpos function</a></h5>
<p><!--para 6 -->
The fseek function returns nonzero only for a request that cannot be satisfied.
<p><b> Forward references</b>: the ftell function (<a href="#7.19.9.4">7.19.9.4</a>).
<h5><a name="7.19.9.3" href="#7.19.9.3">7.19.9.3 The fsetpos function</a></h5>
<p><!--para 2 -->
The fsetpos function sets the mbstate_t object (if any) and file position indicator
for the stream pointed to by stream according to the value of the object pointed to by
<p><!--para 2 -->
The fsetpos function sets the mbstate_t object (if any) and file position indicator
for the stream pointed to by stream according to the value of the object pointed to by
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.
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.
<p><!--para 4 -->
If successful, the fsetpos function returns zero; on failure, the fsetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<h5><a name="7.19.9.4" href="#7.19.9.4">7.19.9.4 The ftell function</a></h5>
<p><!--para 4 -->
If successful, the fsetpos function returns zero; on failure, the fsetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<h5><a name="7.19.9.4" href="#7.19.9.4">7.19.9.4 The ftell function</a></h5>
<p><!--para 2 -->
The ftell function obtains the current value of the file position indicator for the stream
pointed to by stream. For a binary stream, the value is the number of characters from
<p><!--para 2 -->
The ftell function obtains the current value of the file position indicator for the stream
pointed to by stream. For a binary stream, the value is the number of characters from
<p><!--para 3 -->
If successful, the ftell function returns the current value of the file position indicator
for the stream. On failure, the ftell function returns -1L and stores an
implementation-defined positive value in errno.
<h5><a name="7.19.9.5" href="#7.19.9.5">7.19.9.5 The rewind function</a></h5>
<p><!--para 3 -->
If successful, the ftell function returns the current value of the file position indicator
for the stream. On failure, the ftell function returns -1L and stores an
implementation-defined positive value in errno.
<h5><a name="7.19.9.5" href="#7.19.9.5">7.19.9.5 The rewind function</a></h5>
<p><!--para 2 -->
The rewind function sets the file position indicator for the stream pointed to by
stream to the beginning of the file. It is equivalent to
<pre>
<p><!--para 2 -->
The rewind function sets the file position indicator for the stream pointed to by
stream to the beginning of the file. It is equivalent to
<pre>
<p><!--para 3 -->
The rewind function returns no value.
<h4><a name="7.19.10" href="#7.19.10">7.19.10 Error-handling functions</a></h4>
<h5><a name="7.19.10.1" href="#7.19.10.1">7.19.10.1 The clearerr function</a></h5>
<p><!--para 3 -->
The rewind function returns no value.
<h4><a name="7.19.10" href="#7.19.10">7.19.10 Error-handling functions</a></h4>
<h5><a name="7.19.10.1" href="#7.19.10.1">7.19.10.1 The clearerr function</a></h5>
<p><!--para 3 -->
The clearerr function returns no value.
<!--page 317 -->
<h5><a name="7.19.10.2" href="#7.19.10.2">7.19.10.2 The feof function</a></h5>
<p><!--para 3 -->
The clearerr function returns no value.
<!--page 317 -->
<h5><a name="7.19.10.2" href="#7.19.10.2">7.19.10.2 The feof function</a></h5>
<p><!--para 3 -->
The feof function returns nonzero if and only if the end-of-file indicator is set for
stream.
<h5><a name="7.19.10.3" href="#7.19.10.3">7.19.10.3 The ferror function</a></h5>
<p><!--para 3 -->
The feof function returns nonzero if and only if the end-of-file indicator is set for
stream.
<h5><a name="7.19.10.3" href="#7.19.10.3">7.19.10.3 The ferror function</a></h5>
<p><!--para 3 -->
The ferror function returns nonzero if and only if the error indicator is set for
stream.
<h5><a name="7.19.10.4" href="#7.19.10.4">7.19.10.4 The perror function</a></h5>
<p><!--para 3 -->
The ferror function returns nonzero if and only if the error indicator is set for
stream.
<h5><a name="7.19.10.4" href="#7.19.10.4">7.19.10.4 The perror function</a></h5>
<p><!--para 2 -->
The perror function maps the error number in the integer expression errno to an
error message. It writes a sequence of characters to the standard error stream thus: first
<p><!--para 2 -->
The perror function maps the error number in the integer expression errno to an
error message. It writes a sequence of characters to the standard error stream thus: first
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.
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.
<p><!--para 3 -->
The perror function returns no value.
<p><b> Forward references</b>: the strerror function (<a href="#7.21.6.2">7.21.6.2</a>).
<!--page 318 -->
<p><!--para 3 -->
The perror function returns no value.
<p><b> Forward references</b>: the strerror function (<a href="#7.21.6.2">7.21.6.2</a>).
<!--page 318 -->
<p><!--para 1 -->
The header <a href="#7.20"><stdlib.h></a> declares five types and several functions of general utility, and
defines several macros.<sup><a href="#note257"><b>257)</b></a></sup>
<p><!--para 2 -->
The types declared are size_t and wchar_t (both described in <a href="#7.17">7.17</a>),
<pre>
<p><!--para 1 -->
The header <a href="#7.20"><stdlib.h></a> declares five types and several functions of general utility, and
defines several macros.<sup><a href="#note257"><b>257)</b></a></sup>
<p><!--para 2 -->
The types declared are size_t and wchar_t (both described in <a href="#7.17">7.17</a>),
<pre>
which is a structure type that is the type of the value returned by the lldiv function.
<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>);
<pre>
which is a structure type that is the type of the value returned by the lldiv function.
<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>);
<pre>
which expand to integer constant expressions that can be used as the argument to the
exit function to return unsuccessful or successful termination status, respectively, to the
host environment;
<pre>
which expand to integer constant expressions that can be used as the argument to the
exit function to return unsuccessful or successful termination status, respectively, to the
host environment;
<pre>
which expands to a positive integer expression with type size_t that is the maximum
number of bytes in a multibyte character for the extended character set specified by the
current locale (category LC_CTYPE), which is never greater than MB_LEN_MAX.
which expands to a positive integer expression with type size_t that is the maximum
number of bytes in a multibyte character for the extended character set specified by the
current locale (category LC_CTYPE), which is never greater than MB_LEN_MAX.
<p><!--para 2 -->
The atof function converts the initial portion of the string pointed to by nptr to
double representation. Except for the behavior on error, it is equivalent to
<pre>
<p><!--para 2 -->
The atof function converts the initial portion of the string pointed to by nptr to
double representation. Except for the behavior on error, it is equivalent to
<pre>
<p><!--para 3 -->
The atof function returns the converted value.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>).
<h5><a name="7.20.1.2" href="#7.20.1.2">7.20.1.2 The atoi, atol, and atoll functions</a></h5>
<p><!--para 3 -->
The atof function returns the converted value.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>).
<h5><a name="7.20.1.2" href="#7.20.1.2">7.20.1.2 The atoi, atol, and atoll functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int atoi(const char *nptr);
long int atol(const char *nptr);
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int atoi(const char *nptr);
long int atol(const char *nptr);
<p><!--para 2 -->
The atoi, atol, and atoll functions convert the initial portion of the string pointed
to by nptr to int, long int, and long long int representation, respectively.
<p><!--para 2 -->
The atoi, atol, and atoll functions convert the initial portion of the string pointed
to by nptr to int, long int, and long long int representation, respectively.
<pre>
atoi: (int)strtol(nptr, (char **)NULL, 10)
atol: strtol(nptr, (char **)NULL, 10)
<pre>
atoi: (int)strtol(nptr, (char **)NULL, 10)
atol: strtol(nptr, (char **)NULL, 10)
<p><!--para 3 -->
The atoi, atol, and atoll functions return the converted value.
<p><b> Forward references</b>: the strtol, strtoll, strtoul, and strtoull functions
<p><!--para 3 -->
The atoi, atol, and atoll functions return the converted value.
<p><b> Forward references</b>: the strtol, strtoll, strtoul, and strtoull functions
float strtof(const char * restrict nptr,
char ** restrict endptr);
long double strtold(const char * restrict nptr,
float strtof(const char * restrict nptr,
char ** restrict endptr);
long double strtold(const char * restrict nptr,
<p><!--para 2 -->
The strtod, strtof, and strtold functions convert the initial portion of the string
pointed to by nptr to double, float, and long double representation,
<p><!--para 2 -->
The strtod, strtof, and strtold functions convert the initial portion of the string
pointed to by nptr to double, float, and long double representation,
</ul>
The subject sequence is defined as the longest initial subsequence of the input string,
starting with the first non-white-space character, that is of the expected form. The subject
</ul>
The subject sequence is defined as the longest initial subsequence of the input string,
starting with the first non-white-space character, that is of the expected form. The subject
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.
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.
<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
<!--page 322 -->
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.<sup><a href="#note260"><b>260)</b></a></sup>
<!--page 322 -->
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.<sup><a href="#note260"><b>260)</b></a></sup>
<p><!--para 10 -->
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
<p><!--para 10 -->
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
than the smallest normalized positive number in the return type; whether errno acquires
the value ERANGE is implementation-defined.
than the smallest normalized positive number in the return type; whether errno acquires
the value ERANGE is implementation-defined.
<p><small><a name="note258" href="#note258">258)</a> 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 <a href="#F.5">F.5</a>); the two
methods may yield different results if rounding is toward positive or negative infinity. In either case,
<p><small><a name="note258" href="#note258">258)</a> 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 <a href="#F.5">F.5</a>); the two
methods may yield different results if rounding is toward positive or negative infinity. In either case,
</small>
<h5><a name="7.20.1.4" href="#7.20.1.4">7.20.1.4 The strtol, strtoll, strtoul, and strtoull functions</a></h5>
</small>
<h5><a name="7.20.1.4" href="#7.20.1.4">7.20.1.4 The strtol, strtoll, strtoul, and strtoull functions</a></h5>
unsigned long long int strtoull(
const char * restrict nptr,
char ** restrict endptr,
unsigned long long int strtoull(
const char * restrict nptr,
char ** restrict endptr,
<p><!--para 2 -->
The strtol, strtoll, strtoul, and strtoull functions convert the initial
portion of the string pointed to by nptr to long int, long long int, unsigned
<p><!--para 2 -->
The strtol, strtoll, strtoul, and strtoull functions convert the initial
portion of the string pointed to by nptr to long int, long long int, unsigned
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.
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.
<p><!--para 8 -->
The strtol, strtoll, strtoul, and strtoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
<p><!--para 8 -->
The strtol, strtoll, strtoul, and strtoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
<h4><a name="7.20.2" href="#7.20.2">7.20.2 Pseudo-random sequence generation functions</a></h4>
<h5><a name="7.20.2.1" href="#7.20.2.1">7.20.2.1 The rand function</a></h5>
<h4><a name="7.20.2" href="#7.20.2">7.20.2 Pseudo-random sequence generation functions</a></h4>
<h5><a name="7.20.2.1" href="#7.20.2.1">7.20.2.1 The rand function</a></h5>
<p><!--para 2 -->
The rand function computes a sequence of pseudo-random integers in the range 0 to
RAND_MAX.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the rand function.
<p><!--para 2 -->
The rand function computes a sequence of pseudo-random integers in the range 0 to
RAND_MAX.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the rand function.
<p><!--para 5 -->
The value of the RAND_MAX macro shall be at least 32767.
<h5><a name="7.20.2.2" href="#7.20.2.2">7.20.2.2 The srand function</a></h5>
<p><!--para 5 -->
The value of the RAND_MAX macro shall be at least 32767.
<h5><a name="7.20.2.2" href="#7.20.2.2">7.20.2.2 The srand function</a></h5>
<p><!--para 2 -->
The srand function uses the argument as a seed for a new sequence of pseudo-random
numbers to be returned by subsequent calls to rand. If srand is then called with the
<p><!--para 2 -->
The srand function uses the argument as a seed for a new sequence of pseudo-random
numbers to be returned by subsequent calls to rand. If srand is then called with the
as when srand is first called with a seed value of 1.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the srand function.
as when srand is first called with a seed value of 1.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the srand function.
nonzero value, except that the returned pointer shall not be used to access an object.
<h5><a name="7.20.3.1" href="#7.20.3.1">7.20.3.1 The calloc function</a></h5>
nonzero value, except that the returned pointer shall not be used to access an object.
<h5><a name="7.20.3.1" href="#7.20.3.1">7.20.3.1 The calloc function</a></h5>
<p><!--para 2 -->
The calloc function allocates space for an array of nmemb objects, each of whose size
is size. The space is initialized to all bits zero.<sup><a href="#note261"><b>261)</b></a></sup>
<p><!--para 2 -->
The calloc function allocates space for an array of nmemb objects, each of whose size
is size. The space is initialized to all bits zero.<sup><a href="#note261"><b>261)</b></a></sup>
<p><small><a name="note261" href="#note261">261)</a> Note that this need not be the same as the representation of floating-point zero or a null pointer
constant.
</small>
<h5><a name="7.20.3.2" href="#7.20.3.2">7.20.3.2 The free function</a></h5>
<p><small><a name="note261" href="#note261">261)</a> Note that this need not be the same as the representation of floating-point zero or a null pointer
constant.
</small>
<h5><a name="7.20.3.2" href="#7.20.3.2">7.20.3.2 The free function</a></h5>
<p><!--para 2 -->
The free function causes the space pointed to by ptr to be deallocated, that is, made
available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if
<p><!--para 2 -->
The free function causes the space pointed to by ptr to be deallocated, that is, made
available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if
<!--page 326 -->
realloc function, or if the space has been deallocated by a call to free or realloc,
the behavior is undefined.
<!--page 326 -->
realloc function, or if the space has been deallocated by a call to free or realloc,
the behavior is undefined.
<p><!--para 3 -->
The free function returns no value.
<h5><a name="7.20.3.3" href="#7.20.3.3">7.20.3.3 The malloc function</a></h5>
<p><!--para 3 -->
The free function returns no value.
<h5><a name="7.20.3.3" href="#7.20.3.3">7.20.3.3 The malloc function</a></h5>
<p><!--para 2 -->
The malloc function allocates space for an object whose size is specified by size and
whose value is indeterminate.
<p><!--para 2 -->
The malloc function allocates space for an object whose size is specified by size and
whose value is indeterminate.
<p><!--para 3 -->
The malloc function returns either a null pointer or a pointer to the allocated space.
<h5><a name="7.20.3.4" href="#7.20.3.4">7.20.3.4 The realloc function</a></h5>
<p><!--para 3 -->
The malloc function returns either a null pointer or a pointer to the allocated space.
<h5><a name="7.20.3.4" href="#7.20.3.4">7.20.3.4 The realloc function</a></h5>
<p><!--para 2 -->
The realloc function deallocates the old object pointed to by ptr and returns a
pointer to a new object that has the size specified by size. The contents of the new
<p><!--para 2 -->
The realloc function deallocates the old object pointed to by ptr and returns a
pointer to a new object that has the size specified by size. The contents of the new
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.
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.
<p><!--para 4 -->
The realloc function returns a pointer to the new object (which may have the same
value as a pointer to the old object), or a null pointer if the new object could not be
<p><!--para 4 -->
The realloc function returns a pointer to the new object (which may have the same
value as a pointer to the old object), or a null pointer if the new object could not be
<h4><a name="7.20.4" href="#7.20.4">7.20.4 Communication with the environment</a></h4>
<h5><a name="7.20.4.1" href="#7.20.4.1">7.20.4.1 The abort function</a></h5>
<h4><a name="7.20.4" href="#7.20.4">7.20.4 Communication with the environment</a></h4>
<h5><a name="7.20.4.1" href="#7.20.4.1">7.20.4.1 The abort function</a></h5>
<p><!--para 2 -->
The abort function causes abnormal program termination to occur, unless the signal
SIGABRT is being caught and the signal handler does not return. Whether open streams
<p><!--para 2 -->
The abort function causes abnormal program termination to occur, unless the signal
SIGABRT is being caught and the signal handler does not return. Whether open streams
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).
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).
<p><!--para 3 -->
The abort function does not return to its caller.
<h5><a name="7.20.4.2" href="#7.20.4.2">7.20.4.2 The atexit function</a></h5>
<p><!--para 3 -->
The abort function does not return to its caller.
<h5><a name="7.20.4.2" href="#7.20.4.2">7.20.4.2 The atexit function</a></h5>
<p><!--para 2 -->
The atexit function registers the function pointed to by func, to be called without
arguments at normal program termination.
<p><!--para 2 -->
The atexit function registers the function pointed to by func, to be called without
arguments at normal program termination.
<p><!--para 4 -->
The atexit function returns zero if the registration succeeds, nonzero if it fails.
<p><b> Forward references</b>: the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
<h5><a name="7.20.4.3" href="#7.20.4.3">7.20.4.3 The exit function</a></h5>
<p><!--para 4 -->
The atexit function returns zero if the registration succeeds, nonzero if it fails.
<p><b> Forward references</b>: the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
<h5><a name="7.20.4.3" href="#7.20.4.3">7.20.4.3 The exit function</a></h5>
<p><!--para 2 -->
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.
<p><!--para 2 -->
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.
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.
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.
<p><small><a name="note262" href="#note262">262)</a> Each function is called as many times as it was registered, and in the correct order with respect to
other registered functions.
</small>
<h5><a name="7.20.4.4" href="#7.20.4.4">7.20.4.4 The _Exit function</a></h5>
<p><small><a name="note262" href="#note262">262)</a> Each function is called as many times as it was registered, and in the correct order with respect to
other registered functions.
</small>
<h5><a name="7.20.4.4" href="#7.20.4.4">7.20.4.4 The _Exit function</a></h5>
<p><!--para 2 -->
The _Exit function causes normal program termination to occur and control to be
returned to the host environment. No functions registered by the atexit function or
<p><!--para 2 -->
The _Exit function causes normal program termination to occur and control to be
returned to the host environment. No functions registered by the atexit function or
host environment is determined in the same way as for the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
Whether open streams with unwritten buffered data are flushed, open streams are closed,
or temporary files are removed is implementation-defined.
host environment is determined in the same way as for the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
Whether open streams with unwritten buffered data are flushed, open streams are closed,
or temporary files are removed is implementation-defined.
<p><!--para 2 -->
The getenv function searches an environment list, provided by the host environment,
for a string that matches the string pointed to by name. The set of environment names
and the method for altering the environment list are implementation-defined.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the getenv function.
<p><!--para 2 -->
The getenv function searches an environment list, provided by the host environment,
for a string that matches the string pointed to by name. The set of environment names
and the method for altering the environment list are implementation-defined.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the getenv function.
<p><!--para 4 -->
The getenv function returns a pointer to a string associated with the matched list
member. The string pointed to shall not be modified by the program, but may be
<p><!--para 4 -->
The getenv function returns a pointer to a string associated with the matched list
member. The string pointed to shall not be modified by the program, but may be
be found, a null pointer is returned.
<h5><a name="7.20.4.6" href="#7.20.4.6">7.20.4.6 The system function</a></h5>
be found, a null pointer is returned.
<h5><a name="7.20.4.6" href="#7.20.4.6">7.20.4.6 The system function</a></h5>
<p><!--para 2 -->
If string is a null pointer, the system function determines whether the host
environment has a command processor. If string is not a null pointer, the system
function passes the string pointed to by string to that command processor to be
executed in a manner which the implementation shall document; this might then cause the
program calling system to behave in a non-conforming manner or to terminate.
<p><!--para 2 -->
If string is a null pointer, the system function determines whether the host
environment has a command processor. If string is not a null pointer, the system
function passes the string pointed to by string to that command processor to be
executed in a manner which the implementation shall document; this might then cause the
program calling system to behave in a non-conforming manner or to terminate.
<p><!--para 3 -->
If the argument is a null pointer, the system function returns nonzero only if a
command processor is available. If the argument is not a null pointer, and the system
<p><!--para 3 -->
If the argument is a null pointer, the system function returns nonzero only if a
command processor is available. If the argument is not a null pointer, and the system
comparison function, and also between any call to the comparison function and any
movement of the objects passed as arguments to that call.
comparison function, and also between any call to the comparison function and any
movement of the objects passed as arguments to that call.
<p><small><a name="note263" href="#note263">263)</a> That is, if the value passed is p, then the following expressions are always nonzero:
<pre>
((char *)p - (char *)base) % size == 0
(char *)p >= (char *)base
<p><small><a name="note263" href="#note263">263)</a> That is, if the value passed is p, then the following expressions are always nonzero:
<pre>
((char *)p - (char *)base) % size == 0
(char *)p >= (char *)base
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
<p><!--para 2 -->
The bsearch function searches an array of nmemb objects, the initial element of which
is pointed to by base, for an element that matches the object pointed to by key. The
<p><!--para 2 -->
The bsearch function searches an array of nmemb objects, the initial element of which
is pointed to by base, for an element that matches the object pointed to by key. The
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.<sup><a href="#note264"><b>264)</b></a></sup>
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.<sup><a href="#note264"><b>264)</b></a></sup>
<p><!--para 4 -->
The bsearch function returns a pointer to a matching element of the array, or a null
pointer if no match is found. If two elements compare as equal, which element is
matched is unspecified.
<p><!--para 4 -->
The bsearch function returns a pointer to a matching element of the array, or a null
pointer if no match is found. If two elements compare as equal, which element is
matched is unspecified.
<p><small><a name="note264" href="#note264">264)</a> In practice, the entire array is sorted according to the comparison function.
</small>
<h5><a name="7.20.5.2" href="#7.20.5.2">7.20.5.2 The qsort function</a></h5>
<p><small><a name="note264" href="#note264">264)</a> In practice, the entire array is sorted according to the comparison function.
</small>
<h5><a name="7.20.5.2" href="#7.20.5.2">7.20.5.2 The qsort function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void qsort(void *base, size_t nmemb, size_t size,
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void qsort(void *base, size_t nmemb, size_t size,
<p><!--para 2 -->
The qsort function sorts an array of nmemb objects, the initial element of which is
pointed to by base. The size of each object is specified by size.
<p><!--para 2 -->
The qsort function sorts an array of nmemb objects, the initial element of which is
pointed to by base. The size of each object is specified by size.
or greater than the second.
<p><!--para 4 -->
If two elements compare as equal, their order in the resulting sorted array is unspecified.
or greater than the second.
<p><!--para 4 -->
If two elements compare as equal, their order in the resulting sorted array is unspecified.
<h4><a name="7.20.6" href="#7.20.6">7.20.6 Integer arithmetic functions</a></h4>
<h5><a name="7.20.6.1" href="#7.20.6.1">7.20.6.1 The abs, labs and llabs functions</a></h5>
<h4><a name="7.20.6" href="#7.20.6">7.20.6 Integer arithmetic functions</a></h4>
<h5><a name="7.20.6.1" href="#7.20.6.1">7.20.6.1 The abs, labs and llabs functions</a></h5>
<p><!--para 2 -->
The abs, labs, and llabs functions compute the absolute value of an integer j. If the
result cannot be represented, the behavior is undefined.<sup><a href="#note265"><b>265)</b></a></sup>
<p><!--para 2 -->
The abs, labs, and llabs functions compute the absolute value of an integer j. If the
result cannot be represented, the behavior is undefined.<sup><a href="#note265"><b>265)</b></a></sup>
<p><!--para 3 -->
The abs, labs, and llabs, functions return the absolute value.
<p><!--para 3 -->
The abs, labs, and llabs, functions return the absolute value.
<p><small><a name="note265" href="#note265">265)</a> The absolute value of the most negative number cannot be represented in two's complement.
</small>
<h5><a name="7.20.6.2" href="#7.20.6.2">7.20.6.2 The div, ldiv, and lldiv functions</a></h5>
<p><small><a name="note265" href="#note265">265)</a> The absolute value of the most negative number cannot be represented in two's complement.
</small>
<h5><a name="7.20.6.2" href="#7.20.6.2">7.20.6.2 The div, ldiv, and lldiv functions</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
div_t div(int numer, int denom);
ldiv_t ldiv(long int numer, long int denom);
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
div_t div(int numer, int denom);
ldiv_t ldiv(long int numer, long int denom);
<p><!--para 2 -->
The div, ldiv, and lldiv, functions compute numer / denom and numer %
denom in a single operation.
<p><!--para 2 -->
The div, ldiv, and lldiv, functions compute numer / denom and numer %
denom in a single operation.
<p><!--para 3 -->
The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and
lldiv_t, respectively, comprising both the quotient and the remainder. The structures
<p><!--para 3 -->
The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and
lldiv_t, respectively, comprising both the quotient and the remainder. The structures
otherwise.<sup><a href="#note266"><b>266)</b></a></sup> Changing the LC_CTYPE category causes the conversion state of these
functions to be indeterminate.
otherwise.<sup><a href="#note266"><b>266)</b></a></sup> Changing the LC_CTYPE category causes the conversion state of these
functions to be indeterminate.
<p><small><a name="note266" href="#note266">266)</a> 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.
</small>
<h5><a name="7.20.7.1" href="#7.20.7.1">7.20.7.1 The mblen function</a></h5>
<p><small><a name="note266" href="#note266">266)</a> 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.
</small>
<h5><a name="7.20.7.1" href="#7.20.7.1">7.20.7.1 The mblen function</a></h5>
<p><!--para 2 -->
If s is not a null pointer, the mblen function determines the number of bytes contained
in the multibyte character pointed to by s. Except that the conversion state of the
mbtowc function is not affected, it is equivalent to
<p><!--para 2 -->
If s is not a null pointer, the mblen function determines the number of bytes contained
in the multibyte character pointed to by s. Except that the conversion state of the
mbtowc function is not affected, it is equivalent to
<p><!--para 4 -->
If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
<p><!--para 4 -->
If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int mbtowc(wchar_t * restrict pwc,
const char * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int mbtowc(wchar_t * restrict pwc,
const char * restrict s,
<p><!--para 2 -->
If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
<p><!--para 2 -->
If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
character, the function is left in the initial conversion state.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the mbtowc function.
character, the function is left in the initial conversion state.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the mbtowc function.
<p><!--para 4 -->
If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
<p><!--para 4 -->
If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
<p><!--para 2 -->
The wctomb function determines the number of bytes needed to represent the multibyte
character corresponding to the wide character given by wc (including any shift
<p><!--para 2 -->
The wctomb function determines the number of bytes needed to represent the multibyte
character corresponding to the wide character given by wc (including any shift
<p><!--para 4 -->
If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
<p><!--para 4 -->
If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s,
<p><!--para 2 -->
The mbstowcs function converts a sequence of multibyte characters that begins in the
initial shift state from the array pointed to by s into a sequence of corresponding wide
<p><!--para 2 -->
The mbstowcs function converts a sequence of multibyte characters that begins in the
initial shift state from the array pointed to by s into a sequence of corresponding wide
<p><!--para 3 -->
No more than n elements will be modified in the array pointed to by pwcs. If copying
takes place between objects that overlap, the behavior is undefined.
<p><!--para 3 -->
No more than n elements will be modified in the array pointed to by pwcs. If copying
takes place between objects that overlap, the behavior is undefined.
<p><!--para 4 -->
If an invalid multibyte character is encountered, the mbstowcs function returns
(size_t)(-1). Otherwise, the mbstowcs function returns the number of array
<p><!--para 4 -->
If an invalid multibyte character is encountered, the mbstowcs function returns
(size_t)(-1). Otherwise, the mbstowcs function returns the number of array
<p><small><a name="note267" href="#note267">267)</a> The array will not be null-terminated if the value returned is n.
</small>
<h5><a name="7.20.8.2" href="#7.20.8.2">7.20.8.2 The wcstombs function</a></h5>
<p><small><a name="note267" href="#note267">267)</a> The array will not be null-terminated if the value returned is n.
</small>
<h5><a name="7.20.8.2" href="#7.20.8.2">7.20.8.2 The wcstombs function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t wcstombs(char * restrict s,
const wchar_t * restrict pwcs,
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t wcstombs(char * restrict s,
const wchar_t * restrict pwcs,
<p><!--para 2 -->
The wcstombs function converts a sequence of wide characters from the array pointed
to by pwcs into a sequence of corresponding multibyte characters that begins in the
<p><!--para 2 -->
The wcstombs function converts a sequence of wide characters from the array pointed
to by pwcs into a sequence of corresponding multibyte characters that begins in the
<p><!--para 3 -->
No more than n bytes will be modified in the array pointed to by s. If copying takes place
between objects that overlap, the behavior is undefined.
<p><!--para 3 -->
No more than n bytes will be modified in the array pointed to by s. If copying takes place
between objects that overlap, the behavior is undefined.
<p><!--para 4 -->
If a wide character is encountered that does not correspond to a valid multibyte character,
the wcstombs function returns (size_t)(-1). Otherwise, the wcstombs function
<p><!--para 4 -->
If a wide character is encountered that does not correspond to a valid multibyte character,
the wcstombs function returns (size_t)(-1). Otherwise, the wcstombs function
<p><small><a name="note268" href="#note268">268)</a> See ''future library directions'' (<a href="#7.26.11">7.26.11</a>).
</small>
<h4><a name="7.21.2" href="#7.21.2">7.21.2 Copying functions</a></h4>
<h5><a name="7.21.2.1" href="#7.21.2.1">7.21.2.1 The memcpy function</a></h5>
<p><small><a name="note268" href="#note268">268)</a> See ''future library directions'' (<a href="#7.26.11">7.26.11</a>).
</small>
<h4><a name="7.21.2" href="#7.21.2">7.21.2 Copying functions</a></h4>
<h5><a name="7.21.2.1" href="#7.21.2.1">7.21.2.1 The memcpy function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memcpy(void * restrict s1,
const void * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memcpy(void * restrict s1,
const void * restrict s2,
<p><!--para 2 -->
The memcpy function copies n characters from the object pointed to by s2 into the
object pointed to by s1. If copying takes place between objects that overlap, the behavior
is undefined.
<p><!--para 2 -->
The memcpy function copies n characters from the object pointed to by s2 into the
object pointed to by s1. If copying takes place between objects that overlap, the behavior
is undefined.
<p><!--para 2 -->
The memmove function copies n characters from the object pointed to by s2 into the
object pointed to by s1. Copying takes place as if the n characters from the object
pointed to by s2 are first copied into a temporary array of n characters that does not
overlap the objects pointed to by s1 and s2, and then the n characters from the
temporary array are copied into the object pointed to by s1.
<p><!--para 2 -->
The memmove function copies n characters from the object pointed to by s2 into the
object pointed to by s1. Copying takes place as if the n characters from the object
pointed to by s2 are first copied into a temporary array of n characters that does not
overlap the objects pointed to by s1 and s2, and then the n characters from the
temporary array are copied into the object pointed to by s1.
<p><!--para 3 -->
The memmove function returns the value of s1.
<h5><a name="7.21.2.3" href="#7.21.2.3">7.21.2.3 The strcpy function</a></h5>
<p><!--para 3 -->
The memmove function returns the value of s1.
<h5><a name="7.21.2.3" href="#7.21.2.3">7.21.2.3 The strcpy function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcpy(char * restrict s1,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcpy(char * restrict s1,
<p><!--para 2 -->
The strcpy function copies the string pointed to by s2 (including the terminating null
character) into the array pointed to by s1. If copying takes place between objects that
overlap, the behavior is undefined.
<p><!--para 2 -->
The strcpy function copies the string pointed to by s2 (including the terminating null
character) into the array pointed to by s1. If copying takes place between objects that
overlap, the behavior is undefined.
<p><!--para 3 -->
The strcpy function returns the value of s1.
<h5><a name="7.21.2.4" href="#7.21.2.4">7.21.2.4 The strncpy function</a></h5>
<p><!--para 3 -->
The strcpy function returns the value of s1.
<h5><a name="7.21.2.4" href="#7.21.2.4">7.21.2.4 The strncpy function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncpy(char * restrict s1,
const char * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncpy(char * restrict s1,
const char * restrict s2,
<p><!--para 2 -->
The strncpy function copies not more than n characters (characters that follow a null
character are not copied) from the array pointed to by s2 to the array pointed to by
<p><!--para 2 -->
The strncpy function copies not more than n characters (characters that follow a null
character are not copied) from the array pointed to by s2 to the array pointed to by
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.
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.
<p><small><a name="note269" href="#note269">269)</a> 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.
</small>
<p><small><a name="note269" href="#note269">269)</a> 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.
</small>
<h4><a name="7.21.3" href="#7.21.3">7.21.3 Concatenation functions</a></h4>
<h5><a name="7.21.3.1" href="#7.21.3.1">7.21.3.1 The strcat function</a></h5>
<h4><a name="7.21.3" href="#7.21.3">7.21.3 Concatenation functions</a></h4>
<h5><a name="7.21.3.1" href="#7.21.3.1">7.21.3.1 The strcat function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcat(char * restrict s1,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcat(char * restrict s1,
<p><!--para 2 -->
The strcat function appends a copy of the string pointed to by s2 (including the
terminating null character) to the end of the string pointed to by s1. The initial character
of s2 overwrites the null character at the end of s1. If copying takes place between
objects that overlap, the behavior is undefined.
<p><!--para 2 -->
The strcat function appends a copy of the string pointed to by s2 (including the
terminating null character) to the end of the string pointed to by s1. The initial character
of s2 overwrites the null character at the end of s1. If copying takes place between
objects that overlap, the behavior is undefined.
<p><!--para 3 -->
The strcat function returns the value of s1.
<h5><a name="7.21.3.2" href="#7.21.3.2">7.21.3.2 The strncat function</a></h5>
<p><!--para 3 -->
The strcat function returns the value of s1.
<h5><a name="7.21.3.2" href="#7.21.3.2">7.21.3.2 The strncat function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncat(char * restrict s1,
const char * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncat(char * restrict s1,
const char * restrict s2,
<p><!--para 2 -->
The strncat function appends not more than n characters (a null character and
characters that follow it are not appended) from the array pointed to by s2 to the end of
<p><!--para 2 -->
The strncat function appends not more than n characters (a null character and
characters that follow it are not appended) from the array pointed to by s2 to the end of
<p><!--para 3 -->
The strncat function returns the value of s1.
<p><b> Forward references</b>: the strlen function (<a href="#7.21.6.3">7.21.6.3</a>).
<p><!--para 3 -->
The strncat function returns the value of s1.
<p><b> Forward references</b>: the strlen function (<a href="#7.21.6.3">7.21.6.3</a>).
<p><!--para 2 -->
The memcmp function compares the first n characters of the object pointed to by s1 to
the first n characters of the object pointed to by s2.<sup><a href="#note271"><b>271)</b></a></sup>
<p><!--para 2 -->
The memcmp function compares the first n characters of the object pointed to by s1 to
the first n characters of the object pointed to by s2.<sup><a href="#note271"><b>271)</b></a></sup>
<p><!--para 3 -->
The memcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
<p><!--para 3 -->
The memcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
<p><small><a name="note271" href="#note271">271)</a> 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.
</small>
<h5><a name="7.21.4.2" href="#7.21.4.2">7.21.4.2 The strcmp function</a></h5>
<p><small><a name="note271" href="#note271">271)</a> 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.
</small>
<h5><a name="7.21.4.2" href="#7.21.4.2">7.21.4.2 The strcmp function</a></h5>
<p><!--para 3 -->
The strcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
<p><!--para 3 -->
The strcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
<p><!--para 2 -->
The strcoll function compares the string pointed to by s1 to the string pointed to by
s2, both interpreted as appropriate to the LC_COLLATE category of the current locale.
<p><!--para 2 -->
The strcoll function compares the string pointed to by s1 to the string pointed to by
s2, both interpreted as appropriate to the LC_COLLATE category of the current locale.
<p><!--para 3 -->
The strcoll function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
pointed to by s2 when both are interpreted as appropriate to the current locale.
<h5><a name="7.21.4.4" href="#7.21.4.4">7.21.4.4 The strncmp function</a></h5>
<p><!--para 3 -->
The strcoll function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
pointed to by s2 when both are interpreted as appropriate to the current locale.
<h5><a name="7.21.4.4" href="#7.21.4.4">7.21.4.4 The strncmp function</a></h5>
<p><!--para 2 -->
The strncmp function compares not more than n characters (characters that follow a
null character are not compared) from the array pointed to by s1 to the array pointed to
by s2.
<p><!--para 2 -->
The strncmp function compares not more than n characters (characters that follow a
null character are not compared) from the array pointed to by s1 to the array pointed to
by s2.
<p><!--para 3 -->
The strncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<h5><a name="7.21.4.5" href="#7.21.4.5">7.21.4.5 The strxfrm function</a></h5>
<p><!--para 3 -->
The strncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<h5><a name="7.21.4.5" href="#7.21.4.5">7.21.4.5 The strxfrm function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strxfrm(char * restrict s1,
const char * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strxfrm(char * restrict s1,
const char * restrict s2,
<p><!--para 2 -->
The strxfrm function transforms the string pointed to by s2 and places the resulting
string into the array pointed to by s1. The transformation is such that if the strcmp
<p><!--para 2 -->
The strxfrm function transforms the string pointed to by s2 and places the resulting
string into the array pointed to by s1. The transformation is such that if the strcmp
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.
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.
<p><!--para 3 -->
The strxfrm function returns the length of the transformed string (not including the
terminating null character). If the value returned is n or more, the contents of the array
<p><!--para 3 -->
The strxfrm function returns the length of the transformed string (not including the
terminating null character). If the value returned is n or more, the contents of the array
EXAMPLE The value of the following expression is the size of the array needed to hold the
transformation of the string pointed to by s.
<pre>
EXAMPLE The value of the following expression is the size of the array needed to hold the
transformation of the string pointed to by s.
<pre>
<h4><a name="7.21.5" href="#7.21.5">7.21.5 Search functions</a></h4>
<h5><a name="7.21.5.1" href="#7.21.5.1">7.21.5.1 The memchr function</a></h5>
<h4><a name="7.21.5" href="#7.21.5">7.21.5 Search functions</a></h4>
<h5><a name="7.21.5.1" href="#7.21.5.1">7.21.5.1 The memchr function</a></h5>
<p><!--para 2 -->
The memchr function locates the first occurrence of c (converted to an unsigned
char) in the initial n characters (each interpreted as unsigned char) of the object
pointed to by s.
<p><!--para 2 -->
The memchr function locates the first occurrence of c (converted to an unsigned
char) in the initial n characters (each interpreted as unsigned char) of the object
pointed to by s.
<p><!--para 3 -->
The memchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the object.
<h5><a name="7.21.5.2" href="#7.21.5.2">7.21.5.2 The strchr function</a></h5>
<p><!--para 3 -->
The memchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the object.
<h5><a name="7.21.5.2" href="#7.21.5.2">7.21.5.2 The strchr function</a></h5>
<p><!--para 2 -->
The strchr function locates the first occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
<p><!--para 2 -->
The strchr function locates the first occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
<p><!--para 3 -->
The strchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the string.
<!--page 343 -->
<h5><a name="7.21.5.3" href="#7.21.5.3">7.21.5.3 The strcspn function</a></h5>
<p><!--para 3 -->
The strchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the string.
<!--page 343 -->
<h5><a name="7.21.5.3" href="#7.21.5.3">7.21.5.3 The strcspn function</a></h5>
<p><!--para 2 -->
The strcspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters not from the string pointed to by
s2.
<p><!--para 2 -->
The strcspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters not from the string pointed to by
s2.
<p><!--para 3 -->
The strcspn function returns the length of the segment.
<h5><a name="7.21.5.4" href="#7.21.5.4">7.21.5.4 The strpbrk function</a></h5>
<p><!--para 3 -->
The strcspn function returns the length of the segment.
<h5><a name="7.21.5.4" href="#7.21.5.4">7.21.5.4 The strpbrk function</a></h5>
<p><!--para 2 -->
The strpbrk function locates the first occurrence in the string pointed to by s1 of any
character from the string pointed to by s2.
<p><!--para 2 -->
The strpbrk function locates the first occurrence in the string pointed to by s1 of any
character from the string pointed to by s2.
<p><!--para 3 -->
The strpbrk function returns a pointer to the character, or a null pointer if no character
from s2 occurs in s1.
<h5><a name="7.21.5.5" href="#7.21.5.5">7.21.5.5 The strrchr function</a></h5>
<p><!--para 3 -->
The strpbrk function returns a pointer to the character, or a null pointer if no character
from s2 occurs in s1.
<h5><a name="7.21.5.5" href="#7.21.5.5">7.21.5.5 The strrchr function</a></h5>
<p><!--para 2 -->
The strrchr function locates the last occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
<p><!--para 2 -->
The strrchr function locates the last occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
<p><!--para 3 -->
The strrchr function returns a pointer to the character, or a null pointer if c does not
occur in the string.
<!--page 344 -->
<h5><a name="7.21.5.6" href="#7.21.5.6">7.21.5.6 The strspn function</a></h5>
<p><!--para 3 -->
The strrchr function returns a pointer to the character, or a null pointer if c does not
occur in the string.
<!--page 344 -->
<h5><a name="7.21.5.6" href="#7.21.5.6">7.21.5.6 The strspn function</a></h5>
<p><!--para 2 -->
The strspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters from the string pointed to by s2.
<p><!--para 2 -->
The strspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters from the string pointed to by s2.
<p><!--para 3 -->
The strspn function returns the length of the segment.
<h5><a name="7.21.5.7" href="#7.21.5.7">7.21.5.7 The strstr function</a></h5>
<p><!--para 3 -->
The strspn function returns the length of the segment.
<h5><a name="7.21.5.7" href="#7.21.5.7">7.21.5.7 The strstr function</a></h5>
<p><!--para 2 -->
The strstr function locates the first occurrence in the string pointed to by s1 of the
sequence of characters (excluding the terminating null character) in the string pointed to
by s2.
<p><!--para 2 -->
The strstr function locates the first occurrence in the string pointed to by s1 of the
sequence of characters (excluding the terminating null character) in the string pointed to
by s2.
<p><!--para 3 -->
The strstr function returns a pointer to the located string, or a null pointer if the string
is not found. If s2 points to a string with zero length, the function returns s1.
<h5><a name="7.21.5.8" href="#7.21.5.8">7.21.5.8 The strtok function</a></h5>
<p><!--para 3 -->
The strstr function returns a pointer to the located string, or a null pointer if the string
is not found. If s2 points to a string with zero length, the function returns s1.
<h5><a name="7.21.5.8" href="#7.21.5.8">7.21.5.8 The strtok function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strtok(char * restrict s1,
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strtok(char * restrict s1,
<p><!--para 2 -->
A sequence of calls to the strtok function breaks the string pointed to by s1 into a
sequence of tokens, each of which is delimited by a character from the string pointed to
<p><!--para 2 -->
A sequence of calls to the strtok function breaks the string pointed to by s1 into a
sequence of tokens, each of which is delimited by a character from the string pointed to
searching from the saved pointer and behaves as described above.
<p><!--para 6 -->
The implementation shall behave as if no library function calls the strtok function.
searching from the saved pointer and behaves as described above.
<p><!--para 6 -->
The implementation shall behave as if no library function calls the strtok function.
t = strtok(str, "?"); // t points to the token "a"
t = strtok(NULL, ","); // t points to the token "??b"
t = strtok(NULL, "#,"); // t points to the token "c"
t = strtok(str, "?"); // t points to the token "a"
t = strtok(NULL, ","); // t points to the token "??b"
t = strtok(NULL, "#,"); // t points to the token "c"
<h4><a name="7.21.6" href="#7.21.6">7.21.6 Miscellaneous functions</a></h4>
<h5><a name="7.21.6.1" href="#7.21.6.1">7.21.6.1 The memset function</a></h5>
<h4><a name="7.21.6" href="#7.21.6">7.21.6 Miscellaneous functions</a></h4>
<h5><a name="7.21.6.1" href="#7.21.6.1">7.21.6.1 The memset function</a></h5>
<p><!--para 2 -->
The memset function copies the value of c (converted to an unsigned char) into
each of the first n characters of the object pointed to by s.
<p><!--para 2 -->
The memset function copies the value of c (converted to an unsigned char) into
each of the first n characters of the object pointed to by s.
<p><!--para 3 -->
The memset function returns the value of s.
<!--page 346 -->
<h5><a name="7.21.6.2" href="#7.21.6.2">7.21.6.2 The strerror function</a></h5>
<p><!--para 3 -->
The memset function returns the value of s.
<!--page 346 -->
<h5><a name="7.21.6.2" href="#7.21.6.2">7.21.6.2 The strerror function</a></h5>
<p><!--para 2 -->
The strerror function maps the number in errnum to a message string. Typically,
the values for errnum come from errno, but strerror shall map any value of type
int to a message.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the strerror function.
<p><!--para 2 -->
The strerror function maps the number in errnum to a message string. Typically,
the values for errnum come from errno, but strerror shall map any value of type
int to a message.
<p><!--para 3 -->
The implementation shall behave as if no library function calls the strerror function.
<p><!--para 4 -->
The strerror function returns a pointer to the string, the contents of which are locale-
specific. The array pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the strerror function.
<h5><a name="7.21.6.3" href="#7.21.6.3">7.21.6.3 The strlen function</a></h5>
<p><!--para 4 -->
The strerror function returns a pointer to the string, the contents of which are locale-
specific. The array pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the strerror function.
<h5><a name="7.21.6.3" href="#7.21.6.3">7.21.6.3 The strlen function</a></h5>
<p><!--para 1 -->
The header <a href="#7.22"><tgmath.h></a> includes the headers <a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> and
defines several type-generic macros.
<p><!--para 1 -->
The header <a href="#7.22"><tgmath.h></a> includes the headers <a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> and
defines several type-generic macros.
If at least one argument for a generic parameter is complex, then use of the macro invokes
a complex function; otherwise, use of the macro invokes a real function.
<p><!--para 5 -->
If at least one argument for a generic parameter is complex, then use of the macro invokes
a complex function; otherwise, use of the macro invokes a real function.
<p><!--para 5 -->
If all arguments for generic parameters are real, then use of the macro invokes a real
function; otherwise, use of the macro results in undefined behavior.
<p><!--para 6 -->
If all arguments for generic parameters are real, then use of the macro invokes a real
function; otherwise, use of the macro results in undefined behavior.
<p><!--para 6 -->
Use of the macro with any real or complex argument invokes a complex function.
<p><!--para 7 -->
EXAMPLE With the declarations
Use of the macro with any real or complex argument invokes a complex function.
<p><!--para 7 -->
EXAMPLE With the declarations
<p><small><a name="note272" href="#note272">272)</a> Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to
make available the corresponding ordinary function.
</small>
<p><small><a name="note272" href="#note272">272)</a> Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to
make available the corresponding ordinary function.
</small>
which expands to an expression with type clock_t (described below) that is the
number per second of the value returned by the clock function.
<p><!--para 3 -->
The types declared are size_t (described in <a href="#7.17">7.17</a>);
<pre>
which expands to an expression with type clock_t (described below) that is the
number per second of the value returned by the clock function.
<p><!--para 3 -->
The types declared are size_t (described in <a href="#7.17">7.17</a>);
<pre>
which holds the components of a calendar time, called the broken-down time.
<p><!--para 4 -->
The range and precision of times representable in clock_t and time_t are
which holds the components of a calendar time, called the broken-down time.
<p><!--para 4 -->
The range and precision of times representable in clock_t and time_t are
int tm_year; // years since 1900
int tm_wday; // days since Sunday -- [0, 6]
int tm_yday; // days since January 1 -- [0, 365]
int tm_year; // years since 1900
int tm_wday; // days since Sunday -- [0, 6]
int tm_yday; // days since January 1 -- [0, 365]
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.
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.
<p><small><a name="note274" href="#note274">274)</a> The range [0, 60] for tm_sec allows for a positive leap second.
</small>
<h4><a name="7.23.2" href="#7.23.2">7.23.2 Time manipulation functions</a></h4>
<h5><a name="7.23.2.1" href="#7.23.2.1">7.23.2.1 The clock function</a></h5>
<p><small><a name="note274" href="#note274">274)</a> The range [0, 60] for tm_sec allows for a positive leap second.
</small>
<h4><a name="7.23.2" href="#7.23.2">7.23.2 Time manipulation functions</a></h4>
<h5><a name="7.23.2.1" href="#7.23.2.1">7.23.2.1 The clock function</a></h5>
<p><!--para 3 -->
The clock function returns the implementation's best approximation to the processor
time used by the program since the beginning of an implementation-defined era related
<p><!--para 3 -->
The clock function returns the implementation's best approximation to the processor
time used by the program since the beginning of an implementation-defined era related
the processor time used is not available or its value cannot be represented, the function
returns the value (clock_t)(-1).<sup><a href="#note275"><b>275)</b></a></sup>
the processor time used is not available or its value cannot be represented, the function
returns the value (clock_t)(-1).<sup><a href="#note275"><b>275)</b></a></sup>
<p><small><a name="note275" href="#note275">275)</a> 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.
</small>
<h5><a name="7.23.2.2" href="#7.23.2.2">7.23.2.2 The difftime function</a></h5>
<p><small><a name="note275" href="#note275">275)</a> 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.
</small>
<h5><a name="7.23.2.2" href="#7.23.2.2">7.23.2.2 The difftime function</a></h5>
<p><!--para 2 -->
The mktime function converts the broken-down time, expressed as local time, in the
structure pointed to by timeptr into a calendar time value with the same encoding as
<p><!--para 2 -->
The mktime function converts the broken-down time, expressed as local time, in the
structure pointed to by timeptr into a calendar time value with the same encoding as
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.
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.
<p><!--para 3 -->
The mktime function returns the specified calendar time encoded as a value of type
time_t. If the calendar time cannot be represented, the function returns the value
<p><!--para 3 -->
The mktime function returns the specified calendar time encoded as a value of type
time_t. If the calendar time cannot be represented, the function returns the value
"Thursday", "Friday", "Saturday", "-unknown-"
};
struct tm time_str;
"Thursday", "Friday", "Saturday", "-unknown-"
};
struct tm time_str;
<p><small><a name="note276" href="#note276">276)</a> 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.
</small>
<h5><a name="7.23.2.4" href="#7.23.2.4">7.23.2.4 The time function</a></h5>
<p><small><a name="note276" href="#note276">276)</a> 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.
</small>
<h5><a name="7.23.2.4" href="#7.23.2.4">7.23.2.4 The time function</a></h5>
<p><!--para 3 -->
The time function returns the implementation's best approximation to the current
calendar time. The value (time_t)(-1) is returned if the calendar time is not
<p><!--para 3 -->
The time function returns the implementation's best approximation to the current
calendar time. The value (time_t)(-1) is returned if the calendar time is not
functions call these functions.
<h5><a name="7.23.3.1" href="#7.23.3.1">7.23.3.1 The asctime function</a></h5>
functions call these functions.
<h5><a name="7.23.3.1" href="#7.23.3.1">7.23.3.1 The asctime function</a></h5>
<p><!--para 2 -->
The asctime function converts the broken-down time in the structure pointed to by
timeptr into a string in the form
<!--page 354 -->
<pre>
<p><!--para 2 -->
The asctime function converts the broken-down time in the structure pointed to by
timeptr into a string in the form
<!--page 354 -->
<pre>
<p><!--para 3 -->
The asctime function returns a pointer to the string.
<h5><a name="7.23.3.2" href="#7.23.3.2">7.23.3.2 The ctime function</a></h5>
<p><!--para 3 -->
The asctime function returns a pointer to the string.
<h5><a name="7.23.3.2" href="#7.23.3.2">7.23.3.2 The ctime function</a></h5>
<p><!--para 2 -->
The ctime function converts the calendar time pointed to by timer to local time in the
form of a string. It is equivalent to
<pre>
<p><!--para 2 -->
The ctime function converts the calendar time pointed to by timer to local time in the
form of a string. It is equivalent to
<pre>
<p><!--para 3 -->
The ctime function returns the pointer returned by the asctime function with that
broken-down time as argument.
<p><!--para 3 -->
The ctime function returns the pointer returned by the asctime function with that
broken-down time as argument.
<p><!--para 2 -->
The gmtime function converts the calendar time pointed to by timer into a broken-
down time, expressed as UTC.
<p><!--para 2 -->
The gmtime function converts the calendar time pointed to by timer into a broken-
down time, expressed as UTC.
<p><!--para 3 -->
The gmtime function returns a pointer to the broken-down time, or a null pointer if the
specified time cannot be converted to UTC.
<h5><a name="7.23.3.4" href="#7.23.3.4">7.23.3.4 The localtime function</a></h5>
<p><!--para 3 -->
The gmtime function returns a pointer to the broken-down time, or a null pointer if the
specified time cannot be converted to UTC.
<h5><a name="7.23.3.4" href="#7.23.3.4">7.23.3.4 The localtime function</a></h5>
<p><!--para 2 -->
The localtime function converts the calendar time pointed to by timer into a
broken-down time, expressed as local time.
<p><!--para 2 -->
The localtime function converts the calendar time pointed to by timer into a
broken-down time, expressed as local time.
<p><!--para 3 -->
The localtime function returns a pointer to the broken-down time, or a null pointer if
the specified time cannot be converted to local time.
<h5><a name="7.23.3.5" href="#7.23.3.5">7.23.3.5 The strftime function</a></h5>
<p><!--para 3 -->
The localtime function returns a pointer to the broken-down time, or a null pointer if
the specified time cannot be converted to local time.
<h5><a name="7.23.3.5" href="#7.23.3.5">7.23.3.5 The strftime function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
<p><!--para 2 -->
The strftime function places characters into the array pointed to by s as controlled by
the string pointed to by format. The format shall be a multibyte character sequence,
<p><!--para 2 -->
The strftime function places characters into the array pointed to by s as controlled by
the string pointed to by format. The format shall be a multibyte character sequence,
<p><!--para 8 -->
If the total number of resulting characters including the terminating null character is not
more than maxsize, the strftime function returns the number of characters placed
<p><!--para 8 -->
If the total number of resulting characters including the terminating null character is not
more than maxsize, the strftime function returns the number of characters placed
which is an object type other than an array type that can hold the conversion state
information necessary to convert between sequences of multibyte characters and wide
characters;
<pre>
which is an object type other than an array type that can hold the conversion state
information necessary to convert between sequences of multibyte characters and wide
characters;
<pre>
which is an integer type unchanged by default argument promotions that can hold any
value corresponding to members of the extended character set, as well as at least one
value that does not correspond to any member of the extended character set (see WEOF
below);<sup><a href="#note278"><b>278)</b></a></sup> and
<pre>
which is an integer type unchanged by default argument promotions that can hold any
value corresponding to members of the extended character set, as well as at least one
value that does not correspond to any member of the extended character set (see WEOF
below);<sup><a href="#note278"><b>278)</b></a></sup> and
<pre>
which is declared as an incomplete structure type (the contents are described in <a href="#7.23.1">7.23.1</a>).
<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>); WCHAR_MIN and WCHAR_MAX
(described in <a href="#7.18.3">7.18.3</a>); and
<pre>
which is declared as an incomplete structure type (the contents are described in <a href="#7.23.1">7.23.1</a>).
<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>); WCHAR_MIN and WCHAR_MAX
(described in <a href="#7.18.3">7.18.3</a>); and
<pre>
which expands to a constant expression of type wint_t whose value does not
correspond to any member of the extended character set.<sup><a href="#note279"><b>279)</b></a></sup> It is accepted (and returned)
by several functions in this subclause to indicate end-of-file, that is, no more input from a
which expands to a constant expression of type wint_t whose value does not
correspond to any member of the extended character set.<sup><a href="#note279"><b>279)</b></a></sup> It is accepted (and returned)
by several functions in this subclause to indicate end-of-file, that is, no more input from a
<p><small><a name="note277" href="#note277">277)</a> See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
</small>
<p><small><a name="note278" href="#note278">278)</a> wchar_t and wint_t can be the same integer type.
<p><small><a name="note277" href="#note277">277)</a> See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
</small>
<p><small><a name="note278" href="#note278">278)</a> wchar_t and wint_t can be the same integer type.
The formatted wide character input/output functions shall behave as if there is a sequence
point after the actions associated with each specifier.<sup><a href="#note280"><b>280)</b></a></sup>
The formatted wide character input/output functions shall behave as if there is a sequence
point after the actions associated with each specifier.<sup><a href="#note280"><b>280)</b></a></sup>
<p><small><a name="note280" href="#note280">280)</a> The fwprintf functions perform writes to memory for the %n specifier.
</small>
<h5><a name="7.24.2.1" href="#7.24.2.1">7.24.2.1 The fwprintf function</a></h5>
<p><small><a name="note280" href="#note280">280)</a> The fwprintf functions perform writes to memory for the %n specifier.
</small>
<h5><a name="7.24.2.1" href="#7.24.2.1">7.24.2.1 The fwprintf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwprintf(FILE * restrict stream,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwprintf(FILE * restrict stream,
<p><!--para 2 -->
The fwprintf function writes output to the stream pointed to by stream, under
control of the wide string pointed to by format that specifies how subsequent arguments
<p><!--para 2 -->
The fwprintf function writes output to the stream pointed to by stream, under
control of the wide string pointed to by format that specifies how subsequent arguments
<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
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.
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.
<p><!--para 14 -->
The fwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<!--page 368 -->
<p><!--para 14 -->
The fwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<!--page 368 -->
int day, hour, min;
fwprintf(stdout, L"%ls, %ls %d, %.2d:%.2d\n",
weekday, month, day, hour, min);
int day, hour, min;
fwprintf(stdout, L"%ls, %ls %d, %.2d:%.2d\n",
weekday, month, day, hour, min);
<p><b> Forward references</b>: the btowc function (<a href="#7.24.6.1.1">7.24.6.1.1</a>), the mbrtowc function
(<a href="#7.24.6.3.2">7.24.6.3.2</a>).
<p><b> Forward references</b>: the btowc function (<a href="#7.24.6.1.1">7.24.6.1.1</a>), the mbrtowc function
(<a href="#7.24.6.3.2">7.24.6.3.2</a>).
<p><small><a name="note281" href="#note281">281)</a> Note that 0 is taken as a flag, not as the beginning of a field width.
</small>
<p><small><a name="note282" href="#note282">282)</a> The results of all floating conversions of a negative zero, and of negative values that round to zero,
<p><small><a name="note281" href="#note281">281)</a> Note that 0 is taken as a flag, not as the beginning of a field width.
</small>
<p><small><a name="note282" href="#note282">282)</a> The results of all floating conversions of a negative zero, and of negative values that round to zero,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwscanf(FILE * restrict stream,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwscanf(FILE * restrict stream,
<p><!--para 2 -->
The fwscanf function reads input from the stream pointed to by stream, under
control of the wide string pointed to by format that specifies the admissible input
<p><!--para 2 -->
The fwscanf function reads input from the stream pointed to by stream, under
control of the wide string pointed to by format that specifies the admissible input
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.
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.
<p><!--para 16 -->
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
<p><!--para 16 -->
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
#include <a href="#7.24"><wchar.h></a>
/* ... */
int n, i; float x; wchar_t name[50];
#include <a href="#7.24"><wchar.h></a>
/* ... */
int n, i; float x; wchar_t name[50];
- n = fwscanf(stdin, L"%d%f%ls", &i, &x, name);</pre>
+ n = fwscanf(stdin, L"%d%f%ls", &i, &x, name);
+</pre>
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
- fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y);</pre>
+ fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y);
+</pre>
will assign to i the value 56 and to x the value 789.0, will skip past 0123, and will assign to y the value
56.0. The next wide character read from the input stream will be a.
will assign to i the value 56 and to x the value 789.0, will skip past 0123, and will assign to y the value
56.0. The next wide character read from the input stream will be a.
wcstol, wcstoll, wcstoul, and wcstoull functions (<a href="#7.24.4.1.2">7.24.4.1.2</a>), the wcrtomb
function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
wcstol, wcstoll, wcstoul, and wcstoull functions (<a href="#7.24.4.1.2">7.24.4.1.2</a>), the wcrtomb
function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
<p><small><a name="note288" href="#note288">288)</a> These white-space wide characters are not counted against a specified field width.
</small>
<p><small><a name="note289" href="#note289">289)</a> fwscanf pushes back at most one input wide character onto the input stream. Therefore, some
<p><small><a name="note288" href="#note288">288)</a> These white-space wide characters are not counted against a specified field width.
</small>
<p><small><a name="note289" href="#note289">289)</a> fwscanf pushes back at most one input wide character onto the input stream. Therefore, some
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swprintf(wchar_t * restrict s,
size_t n,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swprintf(wchar_t * restrict s,
size_t n,
<p><!--para 2 -->
The swprintf function is equivalent to fwprintf, except that the argument s
specifies an array of wide characters into which the generated output is to be written,
rather than written to a stream. No more than n wide characters are written, including a
terminating null wide character, which is always added (unless n is zero).
<p><!--para 2 -->
The swprintf function is equivalent to fwprintf, except that the argument s
specifies an array of wide characters into which the generated output is to be written,
rather than written to a stream. No more than n wide characters are written, including a
terminating null wide character, which is always added (unless n is zero).
<p><!--para 3 -->
The swprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
occurred or if n or more wide characters were requested to be written.
<h5><a name="7.24.2.4" href="#7.24.2.4">7.24.2.4 The swscanf function</a></h5>
<p><!--para 3 -->
The swprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
occurred or if n or more wide characters were requested to be written.
<h5><a name="7.24.2.4" href="#7.24.2.4">7.24.2.4 The swscanf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swscanf(const wchar_t * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swscanf(const wchar_t * restrict s,
<p><!--para 2 -->
The swscanf function is equivalent to fwscanf, except that the argument s specifies a
wide string from which the input is to be obtained, rather than from a stream. Reaching
the end of the wide string is equivalent to encountering end-of-file for the fwscanf
function.
<p><!--para 2 -->
The swscanf function is equivalent to fwscanf, except that the argument s specifies a
wide string from which the input is to be obtained, rather than from a stream. Reaching
the end of the wide string is equivalent to encountering end-of-file for the fwscanf
function.
<p><!--para 3 -->
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
<p><!--para 3 -->
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
#include <a href="#7.24"><wchar.h></a>
int vfwprintf(FILE * restrict stream,
const wchar_t * restrict format,
#include <a href="#7.24"><wchar.h></a>
int vfwprintf(FILE * restrict stream,
const wchar_t * restrict format,
<p><!--para 2 -->
The vfwprintf function is equivalent to fwprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 2 -->
The vfwprintf function is equivalent to fwprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 3 -->
The vfwprintf function returns the number of wide characters transmitted, or a
negative value if an output or encoding error occurred.
<p><!--para 3 -->
The vfwprintf function returns the number of wide characters transmitted, or a
negative value if an output or encoding error occurred.
// print out remainder of message
vfwprintf(stderr, format, args);
va_end(args);
// print out remainder of message
vfwprintf(stderr, format, args);
va_end(args);
<p><small><a name="note291" href="#note291">291)</a> As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
invoke the va_arg macro, the value of arg after the return is indeterminate.
</small>
<h5><a name="7.24.2.6" href="#7.24.2.6">7.24.2.6 The vfwscanf function</a></h5>
<p><small><a name="note291" href="#note291">291)</a> As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
invoke the va_arg macro, the value of arg after the return is indeterminate.
</small>
<h5><a name="7.24.2.6" href="#7.24.2.6">7.24.2.6 The vfwscanf function</a></h5>
#include <a href="#7.24"><wchar.h></a>
int vfwscanf(FILE * restrict stream,
const wchar_t * restrict format,
#include <a href="#7.24"><wchar.h></a>
int vfwscanf(FILE * restrict stream,
const wchar_t * restrict format,
<p><!--para 2 -->
The vfwscanf function is equivalent to fwscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwscanf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 2 -->
The vfwscanf function is equivalent to fwscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwscanf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 3 -->
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
<p><!--para 3 -->
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
int vswprintf(wchar_t * restrict s,
size_t n,
const wchar_t * restrict format,
int vswprintf(wchar_t * restrict s,
size_t n,
const wchar_t * restrict format,
<p><!--para 2 -->
The vswprintf function is equivalent to swprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 2 -->
The vswprintf function is equivalent to swprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 3 -->
The vswprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
<p><!--para 3 -->
The vswprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vswscanf(const wchar_t * restrict s,
const wchar_t * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vswscanf(const wchar_t * restrict s,
const wchar_t * restrict format,
<p><!--para 2 -->
The vswscanf function is equivalent to swscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswscanf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 2 -->
The vswscanf function is equivalent to swscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswscanf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vwprintf(const wchar_t * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vwprintf(const wchar_t * restrict format,
<p><!--para 2 -->
The vwprintf function is equivalent to wprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 2 -->
The vwprintf function is equivalent to wprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 3 -->
The vwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<!--page 378 -->
<h5><a name="7.24.2.10" href="#7.24.2.10">7.24.2.10 The vwscanf function</a></h5>
<p><!--para 3 -->
The vwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<!--page 378 -->
<h5><a name="7.24.2.10" href="#7.24.2.10">7.24.2.10 The vwscanf function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vwscanf(const wchar_t * restrict format,
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vwscanf(const wchar_t * restrict format,
<p><!--para 2 -->
The vwscanf function is equivalent to wscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwscanf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 2 -->
The vwscanf function is equivalent to wscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwscanf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<p><!--para 2 -->
The wprintf function is equivalent to fwprintf with the argument stdout
interposed before the arguments to wprintf.
<p><!--para 2 -->
The wprintf function is equivalent to fwprintf with the argument stdout
interposed before the arguments to wprintf.
<p><!--para 3 -->
The wprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<h5><a name="7.24.2.12" href="#7.24.2.12">7.24.2.12 The wscanf function</a></h5>
<p><!--para 3 -->
The wprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<h5><a name="7.24.2.12" href="#7.24.2.12">7.24.2.12 The wscanf function</a></h5>
<p><!--para 2 -->
The wscanf function is equivalent to fwscanf with the argument stdin interposed
before the arguments to wscanf.
<!--page 379 -->
<p><!--para 2 -->
The wscanf function is equivalent to fwscanf with the argument stdin interposed
before the arguments to wscanf.
<!--page 379 -->
<p><!--para 3 -->
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
<p><!--para 3 -->
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
<h4><a name="7.24.3" href="#7.24.3">7.24.3 Wide character input/output functions</a></h4>
<h5><a name="7.24.3.1" href="#7.24.3.1">7.24.3.1 The fgetwc function</a></h5>
<h4><a name="7.24.3" href="#7.24.3">7.24.3 Wide character input/output functions</a></h4>
<h5><a name="7.24.3.1" href="#7.24.3.1">7.24.3.1 The fgetwc function</a></h5>
<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next wide character is present, the fgetwc function obtains that wide character as a
wchar_t converted to a wint_t and advances the associated file position indicator for
the stream (if defined).
<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next wide character is present, the fgetwc function obtains that wide character as a
wchar_t converted to a wint_t and advances the associated file position indicator for
the stream (if defined).
<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise,
<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise,
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.<sup><a href="#note292"><b>292)</b></a></sup>
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.<sup><a href="#note292"><b>292)</b></a></sup>
<p><small><a name="note292" href="#note292">292)</a> 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.
</small>
<h5><a name="7.24.3.2" href="#7.24.3.2">7.24.3.2 The fgetws function</a></h5>
<p><small><a name="note292" href="#note292">292)</a> 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.
</small>
<h5><a name="7.24.3.2" href="#7.24.3.2">7.24.3.2 The fgetws function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wchar_t *fgetws(wchar_t * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wchar_t *fgetws(wchar_t * restrict s,
<p><!--para 2 -->
The fgetws function reads at most one less than the number of wide characters
specified by n from the stream pointed to by stream into the array pointed to by s. No
<p><!--para 2 -->
The fgetws function reads at most one less than the number of wide characters
specified by n from the stream pointed to by stream into the array pointed to by s. No
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.
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.
<p><!--para 3 -->
The fgetws function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
<p><!--para 3 -->
The fgetws function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
contents are indeterminate and a null pointer is returned.
<h5><a name="7.24.3.3" href="#7.24.3.3">7.24.3.3 The fputwc function</a></h5>
contents are indeterminate and a null pointer is returned.
<h5><a name="7.24.3.3" href="#7.24.3.3">7.24.3.3 The fputwc function</a></h5>
<p><!--para 2 -->
The fputwc function writes the wide character specified by c to the output stream
pointed to by stream, at the position indicated by the associated file position indicator
for the stream (if defined), and advances the indicator appropriately. If the file cannot
support positioning requests, or if the stream was opened with append mode, the
character is appended to the output stream.
<p><!--para 2 -->
The fputwc function writes the wide character specified by c to the output stream
pointed to by stream, at the position indicated by the associated file position indicator
for the stream (if defined), and advances the indicator appropriately. If the file cannot
support positioning requests, or if the stream was opened with append mode, the
character is appended to the output stream.
<p><!--para 3 -->
The fputwc function returns the wide character written. If a write error occurs, the
error indicator for the stream is set and fputwc returns WEOF. If an encoding error
occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF.
<h5><a name="7.24.3.4" href="#7.24.3.4">7.24.3.4 The fputws function</a></h5>
<p><!--para 3 -->
The fputwc function returns the wide character written. If a write error occurs, the
error indicator for the stream is set and fputwc returns WEOF. If an encoding error
occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF.
<h5><a name="7.24.3.4" href="#7.24.3.4">7.24.3.4 The fputws function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fputws(const wchar_t * restrict s,
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fputws(const wchar_t * restrict s,
<p><!--para 2 -->
The fputws function writes the wide string pointed to by s to the stream pointed to by
stream. The terminating null wide character is not written.
<p><!--para 2 -->
The fputws function writes the wide string pointed to by s to the stream pointed to by
stream. The terminating null wide character is not written.
<p><!--para 3 -->
The fputws function returns EOF if a write or encoding error occurs; otherwise, it
returns a nonnegative value.
<!--page 381 -->
<h5><a name="7.24.3.5" href="#7.24.3.5">7.24.3.5 The fwide function</a></h5>
<p><!--para 3 -->
The fputws function returns EOF if a write or encoding error occurs; otherwise, it
returns a nonnegative value.
<!--page 381 -->
<h5><a name="7.24.3.5" href="#7.24.3.5">7.24.3.5 The fwide function</a></h5>
<p><!--para 2 -->
The fwide function determines the orientation of the stream pointed to by stream. If
mode is greater than zero, the function first attempts to make the stream wide oriented. If
mode is less than zero, the function first attempts to make the stream byte oriented.<sup><a href="#note293"><b>293)</b></a></sup>
Otherwise, mode is zero and the function does not alter the orientation of the stream.
<p><!--para 2 -->
The fwide function determines the orientation of the stream pointed to by stream. If
mode is greater than zero, the function first attempts to make the stream wide oriented. If
mode is less than zero, the function first attempts to make the stream byte oriented.<sup><a href="#note293"><b>293)</b></a></sup>
Otherwise, mode is zero and the function does not alter the orientation of the stream.
<p><!--para 3 -->
The fwide function returns a value greater than zero if, after the call, the stream has
wide orientation, a value less than zero if the stream has byte orientation, or zero if the
stream has no orientation.
<p><!--para 3 -->
The fwide function returns a value greater than zero if, after the call, the stream has
wide orientation, a value less than zero if the stream has byte orientation, or zero if the
stream has no orientation.
<p><small><a name="note293" href="#note293">293)</a> If the orientation of the stream has already been determined, fwide does not change it.
</small>
<h5><a name="7.24.3.6" href="#7.24.3.6">7.24.3.6 The getwc function</a></h5>
<p><small><a name="note293" href="#note293">293)</a> If the orientation of the stream has already been determined, fwide does not change it.
</small>
<h5><a name="7.24.3.6" href="#7.24.3.6">7.24.3.6 The getwc function</a></h5>
<p><!--para 2 -->
The getwc function is equivalent to fgetwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so the argument should never be an
expression with side effects.
<p><!--para 2 -->
The getwc function is equivalent to fgetwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so the argument should never be an
expression with side effects.
<p><!--para 3 -->
The getwc function returns the next wide character from the input stream pointed to by
stream, or WEOF.
<h5><a name="7.24.3.7" href="#7.24.3.7">7.24.3.7 The getwchar function</a></h5>
<p><!--para 3 -->
The getwc function returns the next wide character from the input stream pointed to by
stream, or WEOF.
<h5><a name="7.24.3.7" href="#7.24.3.7">7.24.3.7 The getwchar function</a></h5>
<p><!--para 3 -->
The getwchar function returns the next wide character from the input stream pointed to
by stdin, or WEOF.
<h5><a name="7.24.3.8" href="#7.24.3.8">7.24.3.8 The putwc function</a></h5>
<p><!--para 3 -->
The getwchar function returns the next wide character from the input stream pointed to
by stdin, or WEOF.
<h5><a name="7.24.3.8" href="#7.24.3.8">7.24.3.8 The putwc function</a></h5>
<p><!--para 2 -->
The putwc function is equivalent to fputwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so that argument should never be an
expression with side effects.
<p><!--para 2 -->
The putwc function is equivalent to fputwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so that argument should never be an
expression with side effects.
<p><!--para 3 -->
The putwc function returns the wide character written, or WEOF.
<h5><a name="7.24.3.9" href="#7.24.3.9">7.24.3.9 The putwchar function</a></h5>
<p><!--para 3 -->
The putwc function returns the wide character written, or WEOF.
<h5><a name="7.24.3.9" href="#7.24.3.9">7.24.3.9 The putwchar function</a></h5>
<p><!--para 3 -->
The putwchar function returns the character written, or WEOF.
<h5><a name="7.24.3.10" href="#7.24.3.10">7.24.3.10 The ungetwc function</a></h5>
<p><!--para 3 -->
The putwchar function returns the character written, or WEOF.
<h5><a name="7.24.3.10" href="#7.24.3.10">7.24.3.10 The ungetwc function</a></h5>
<p><!--para 2 -->
The ungetwc function pushes the wide character specified by c back onto the input
stream pointed to by stream. Pushed-back wide characters will be returned by
<p><!--para 2 -->
The ungetwc function pushes the wide character specified by c back onto the input
stream pointed to by stream. Pushed-back wide characters will be returned by
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.
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.
<h5><a name="7.24.4.1" href="#7.24.4.1">7.24.4.1 Wide string numeric conversion functions</a></h5>
<h5><a name="7.24.4.1.1" href="#7.24.4.1.1">7.24.4.1.1 The wcstod, wcstof, and wcstold functions</a></h5>
<h5><a name="7.24.4.1" href="#7.24.4.1">7.24.4.1 Wide string numeric conversion functions</a></h5>
<h5><a name="7.24.4.1.1" href="#7.24.4.1.1">7.24.4.1.1 The wcstod, wcstof, and wcstold functions</a></h5>
float wcstof(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);
long double wcstold(const wchar_t * restrict nptr,
float wcstof(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);
long double wcstold(const wchar_t * restrict nptr,
<p><!--para 2 -->
The wcstod, wcstof, and wcstold functions convert the initial portion of the wide
string pointed to by nptr to double, float, and long double representation,
<p><!--para 2 -->
The wcstod, wcstof, and wcstold functions convert the initial portion of the wide
string pointed to by nptr to double, float, and long double representation,
</ul>
The subject sequence is defined as the longest initial subsequence of the input wide
string, starting with the first non-white-space wide character, that is of the expected form.
</ul>
The subject sequence is defined as the longest initial subsequence of the input wide
string, starting with the first non-white-space wide character, that is of the expected form.
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.
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.
<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
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.<sup><a href="#note296"><b>296)</b></a></sup>
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.<sup><a href="#note296"><b>296)</b></a></sup>
<p><!--para 10 -->
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
<p><!--para 10 -->
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
<p><small><a name="note294" href="#note294">294)</a> 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 <a href="#F.5">F.5</a>); the two
methods may yield different results if rounding is toward positive or negative infinity. In either case,
<p><small><a name="note294" href="#note294">294)</a> 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 <a href="#F.5">F.5</a>); the two
methods may yield different results if rounding is toward positive or negative infinity. In either case,
</small>
<h5><a name="7.24.4.1.2" href="#7.24.4.1.2">7.24.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions</a></h5>
</small>
<h5><a name="7.24.4.1.2" href="#7.24.4.1.2">7.24.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions</a></h5>
unsigned long long int wcstoull(
const wchar_t * restrict nptr,
wchar_t ** restrict endptr,
unsigned long long int wcstoull(
const wchar_t * restrict nptr,
wchar_t ** restrict endptr,
<p><!--para 2 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
portion of the wide string pointed to by nptr to long int, long long int,
<p><!--para 2 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
portion of the wide string pointed to by nptr to long int, long long int,
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.
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.
<p><!--para 8 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
<p><!--para 8 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
<h5><a name="7.24.4.2" href="#7.24.4.2">7.24.4.2 Wide string copying functions</a></h5>
<h5><a name="7.24.4.2.1" href="#7.24.4.2.1">7.24.4.2.1 The wcscpy function</a></h5>
<h5><a name="7.24.4.2" href="#7.24.4.2">7.24.4.2 Wide string copying functions</a></h5>
<h5><a name="7.24.4.2.1" href="#7.24.4.2.1">7.24.4.2.1 The wcscpy function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscpy(wchar_t * restrict s1,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscpy(wchar_t * restrict s1,
<p><!--para 2 -->
The wcscpy function copies the wide string pointed to by s2 (including the terminating
null wide character) into the array pointed to by s1.
<p><!--para 2 -->
The wcscpy function copies the wide string pointed to by s2 (including the terminating
null wide character) into the array pointed to by s1.
<p><!--para 3 -->
The wcscpy function returns the value of s1.
<!--page 389 -->
<h5><a name="7.24.4.2.2" href="#7.24.4.2.2">7.24.4.2.2 The wcsncpy function</a></h5>
<p><!--para 3 -->
The wcscpy function returns the value of s1.
<!--page 389 -->
<h5><a name="7.24.4.2.2" href="#7.24.4.2.2">7.24.4.2.2 The wcsncpy function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 2 -->
The wcsncpy function copies not more than n wide characters (those that follow a null
wide character are not copied) from the array pointed to by s2 to the array pointed to by
<p><!--para 2 -->
The wcsncpy function copies not more than n wide characters (those that follow a null
wide character are not copied) from the array pointed to by s2 to the array pointed to by
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.
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.
<p><small><a name="note297" href="#note297">297)</a> 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.
</small>
<h5><a name="7.24.4.2.3" href="#7.24.4.2.3">7.24.4.2.3 The wmemcpy function</a></h5>
<p><small><a name="note297" href="#note297">297)</a> 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.
</small>
<h5><a name="7.24.4.2.3" href="#7.24.4.2.3">7.24.4.2.3 The wmemcpy function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemcpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemcpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
<p><!--para 2 -->
The wmemmove function copies n wide characters from the object pointed to by s2 to
the object pointed to by s1. Copying takes place as if the n wide characters from the
object pointed to by s2 are first copied into a temporary array of n wide characters that
does not overlap the objects pointed to by s1 or s2, and then the n wide characters from
the temporary array are copied into the object pointed to by s1.
<p><!--para 2 -->
The wmemmove function copies n wide characters from the object pointed to by s2 to
the object pointed to by s1. Copying takes place as if the n wide characters from the
object pointed to by s2 are first copied into a temporary array of n wide characters that
does not overlap the objects pointed to by s1 or s2, and then the n wide characters from
the temporary array are copied into the object pointed to by s1.
<p><!--para 3 -->
The wmemmove function returns the value of s1.
<h5><a name="7.24.4.3" href="#7.24.4.3">7.24.4.3 Wide string concatenation functions</a></h5>
<h5><a name="7.24.4.3.1" href="#7.24.4.3.1">7.24.4.3.1 The wcscat function</a></h5>
<p><!--para 3 -->
The wmemmove function returns the value of s1.
<h5><a name="7.24.4.3" href="#7.24.4.3">7.24.4.3 Wide string concatenation functions</a></h5>
<h5><a name="7.24.4.3.1" href="#7.24.4.3.1">7.24.4.3.1 The wcscat function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscat(wchar_t * restrict s1,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscat(wchar_t * restrict s1,
<p><!--para 2 -->
The wcscat function appends a copy of the wide string pointed to by s2 (including the
terminating null wide character) to the end of the wide string pointed to by s1. The initial
wide character of s2 overwrites the null wide character at the end of s1.
<p><!--para 2 -->
The wcscat function appends a copy of the wide string pointed to by s2 (including the
terminating null wide character) to the end of the wide string pointed to by s1. The initial
wide character of s2 overwrites the null wide character at the end of s1.
<p><!--para 3 -->
The wcscat function returns the value of s1.
<h5><a name="7.24.4.3.2" href="#7.24.4.3.2">7.24.4.3.2 The wcsncat function</a></h5>
<p><!--para 3 -->
The wcscat function returns the value of s1.
<h5><a name="7.24.4.3.2" href="#7.24.4.3.2">7.24.4.3.2 The wcsncat function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncat(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncat(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 2 -->
The wcsncat function appends not more than n wide characters (a null wide character
and those that follow it are not appended) from the array pointed to by s2 to the end of
<p><!--para 2 -->
The wcsncat function appends not more than n wide characters (a null wide character
and those that follow it are not appended) from the array pointed to by s2 to the end of
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.<sup><a href="#note298"><b>298)</b></a></sup>
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.<sup><a href="#note298"><b>298)</b></a></sup>
<p><!--para 3 -->
The wcscmp function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
wide string pointed to by s2.
<h5><a name="7.24.4.4.2" href="#7.24.4.4.2">7.24.4.4.2 The wcscoll function</a></h5>
<p><!--para 3 -->
The wcscmp function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
wide string pointed to by s2.
<h5><a name="7.24.4.4.2" href="#7.24.4.4.2">7.24.4.4.2 The wcscoll function</a></h5>
<p><!--para 2 -->
The wcscoll function compares the wide string pointed to by s1 to the wide string
pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the
current locale.
<p><!--para 2 -->
The wcscoll function compares the wide string pointed to by s1 to the wide string
pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the
current locale.
<p><!--para 3 -->
The wcscoll function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
<p><!--para 3 -->
The wcscoll function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
<p><!--para 2 -->
The wcsncmp function compares not more than n wide characters (those that follow a
null wide character are not compared) from the array pointed to by s1 to the array
pointed to by s2.
<p><!--para 2 -->
The wcsncmp function compares not more than n wide characters (those that follow a
null wide character are not compared) from the array pointed to by s1 to the array
pointed to by s2.
<p><!--para 3 -->
The wcsncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<h5><a name="7.24.4.4.4" href="#7.24.4.4.4">7.24.4.4.4 The wcsxfrm function</a></h5>
<p><!--para 3 -->
The wcsncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<h5><a name="7.24.4.4.4" href="#7.24.4.4.4">7.24.4.4.4 The wcsxfrm function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsxfrm(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsxfrm(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 2 -->
The wcsxfrm function transforms the wide string pointed to by s2 and places the
resulting wide string into the array pointed to by s1. The transformation is such that if
<p><!--para 2 -->
The wcsxfrm function transforms the wide string pointed to by s2 and places the
resulting wide string into the array pointed to by s1. The transformation is such that if
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.
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.
<p><!--para 3 -->
The wcsxfrm function returns the length of the transformed wide string (not including
the terminating null wide character). If the value returned is n or greater, the contents of
<p><!--para 3 -->
The wcsxfrm function returns the length of the transformed wide string (not including
the terminating null wide character). If the value returned is n or greater, the contents of
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
<p><!--para 2 -->
The wmemcmp function compares the first n wide characters of the object pointed to by
s1 to the first n wide characters of the object pointed to by s2.
<p><!--para 2 -->
The wmemcmp function compares the first n wide characters of the object pointed to by
s1 to the first n wide characters of the object pointed to by s2.
<p><!--para 3 -->
The wmemcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
<p><!--para 3 -->
The wmemcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
<h5><a name="7.24.4.5" href="#7.24.4.5">7.24.4.5 Wide string search functions</a></h5>
<h5><a name="7.24.4.5.1" href="#7.24.4.5.1">7.24.4.5.1 The wcschr function</a></h5>
<h5><a name="7.24.4.5" href="#7.24.4.5">7.24.4.5 Wide string search functions</a></h5>
<h5><a name="7.24.4.5.1" href="#7.24.4.5.1">7.24.4.5.1 The wcschr function</a></h5>
<p><!--para 2 -->
The wcschr function locates the first occurrence of c in the wide string pointed to by s.
The terminating null wide character is considered to be part of the wide string.
<p><!--para 2 -->
The wcschr function locates the first occurrence of c in the wide string pointed to by s.
The terminating null wide character is considered to be part of the wide string.
<p><!--para 3 -->
The wcschr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the wide string.
<h5><a name="7.24.4.5.2" href="#7.24.4.5.2">7.24.4.5.2 The wcscspn function</a></h5>
<p><!--para 3 -->
The wcschr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the wide string.
<h5><a name="7.24.4.5.2" href="#7.24.4.5.2">7.24.4.5.2 The wcscspn function</a></h5>
<p><!--para 2 -->
The wcscspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters not from the wide
string pointed to by s2.
<!--page 394 -->
<p><!--para 2 -->
The wcscspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters not from the wide
string pointed to by s2.
<!--page 394 -->
<p><!--para 3 -->
The wcscspn function returns the length of the segment.
<h5><a name="7.24.4.5.3" href="#7.24.4.5.3">7.24.4.5.3 The wcspbrk function</a></h5>
<p><!--para 3 -->
The wcscspn function returns the length of the segment.
<h5><a name="7.24.4.5.3" href="#7.24.4.5.3">7.24.4.5.3 The wcspbrk function</a></h5>
<p><!--para 2 -->
The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of
any wide character from the wide string pointed to by s2.
<p><!--para 2 -->
The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of
any wide character from the wide string pointed to by s2.
<p><!--para 3 -->
The wcspbrk function returns a pointer to the wide character in s1, or a null pointer if
no wide character from s2 occurs in s1.
<h5><a name="7.24.4.5.4" href="#7.24.4.5.4">7.24.4.5.4 The wcsrchr function</a></h5>
<p><!--para 3 -->
The wcspbrk function returns a pointer to the wide character in s1, or a null pointer if
no wide character from s2 occurs in s1.
<h5><a name="7.24.4.5.4" href="#7.24.4.5.4">7.24.4.5.4 The wcsrchr function</a></h5>
<p><!--para 2 -->
The wcsrchr function locates the last occurrence of c in the wide string pointed to by
s. The terminating null wide character is considered to be part of the wide string.
<p><!--para 2 -->
The wcsrchr function locates the last occurrence of c in the wide string pointed to by
s. The terminating null wide character is considered to be part of the wide string.
<p><!--para 3 -->
The wcsrchr function returns a pointer to the wide character, or a null pointer if c does
not occur in the wide string.
<h5><a name="7.24.4.5.5" href="#7.24.4.5.5">7.24.4.5.5 The wcsspn function</a></h5>
<p><!--para 3 -->
The wcsrchr function returns a pointer to the wide character, or a null pointer if c does
not occur in the wide string.
<h5><a name="7.24.4.5.5" href="#7.24.4.5.5">7.24.4.5.5 The wcsspn function</a></h5>
<p><!--para 2 -->
The wcsspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters from the wide string
pointed to by s2.
<p><!--para 2 -->
The wcsspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters from the wide string
pointed to by s2.
<p><!--para 3 -->
The wcsspn function returns the length of the segment.
<!--page 395 -->
<h5><a name="7.24.4.5.6" href="#7.24.4.5.6">7.24.4.5.6 The wcsstr function</a></h5>
<p><!--para 3 -->
The wcsspn function returns the length of the segment.
<!--page 395 -->
<h5><a name="7.24.4.5.6" href="#7.24.4.5.6">7.24.4.5.6 The wcsstr function</a></h5>
<p><!--para 2 -->
The wcsstr function locates the first occurrence in the wide string pointed to by s1 of
the sequence of wide characters (excluding the terminating null wide character) in the
wide string pointed to by s2.
<p><!--para 2 -->
The wcsstr function locates the first occurrence in the wide string pointed to by s1 of
the sequence of wide characters (excluding the terminating null wide character) in the
wide string pointed to by s2.
<p><!--para 3 -->
The wcsstr function returns a pointer to the located wide string, or a null pointer if the
wide string is not found. If s2 points to a wide string with zero length, the function
returns s1.
<h5><a name="7.24.4.5.7" href="#7.24.4.5.7">7.24.4.5.7 The wcstok function</a></h5>
<p><!--para 3 -->
The wcsstr function returns a pointer to the located wide string, or a null pointer if the
wide string is not found. If s2 points to a wide string with zero length, the function
returns s1.
<h5><a name="7.24.4.5.7" href="#7.24.4.5.7">7.24.4.5.7 The wcstok function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcstok(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcstok(wchar_t * restrict s1,
const wchar_t * restrict s2,
<p><!--para 2 -->
A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into
a sequence of tokens, each of which is delimited by a wide character from the wide string
<p><!--para 2 -->
A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into
a sequence of tokens, each of which is delimited by a wide character from the wide string
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).
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).
<p><!--para 7 -->
The wcstok function returns a pointer to the first wide character of a token, or a null
pointer if there is no token.
<p><!--para 7 -->
The wcstok function returns a pointer to the first wide character of a token, or a null
pointer if there is no token.
t = wcstok(NULL, L",", &ptr1); // t points to the token L"??b"
t = wcstok(str2, L" \t", &ptr2); // t is a null pointer
t = wcstok(NULL, L"#,", &ptr1); // t points to the token L"c"
t = wcstok(NULL, L",", &ptr1); // t points to the token L"??b"
t = wcstok(str2, L" \t", &ptr2); // t is a null pointer
t = wcstok(NULL, L"#,", &ptr1); // t points to the token L"c"
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
<p><!--para 2 -->
The wmemchr function locates the first occurrence of c in the initial n wide characters of
the object pointed to by s.
<p><!--para 2 -->
The wmemchr function locates the first occurrence of c in the initial n wide characters of
the object pointed to by s.
<p><!--para 3 -->
The wmemchr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the object.
<p><!--para 3 -->
The wmemchr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the object.
<h5><a name="7.24.4.6" href="#7.24.4.6">7.24.4.6 Miscellaneous functions</a></h5>
<h5><a name="7.24.4.6.1" href="#7.24.4.6.1">7.24.4.6.1 The wcslen function</a></h5>
<h5><a name="7.24.4.6" href="#7.24.4.6">7.24.4.6 Miscellaneous functions</a></h5>
<h5><a name="7.24.4.6.1" href="#7.24.4.6.1">7.24.4.6.1 The wcslen function</a></h5>
<p><!--para 3 -->
The wcslen function returns the number of wide characters that precede the terminating
null wide character.
<h5><a name="7.24.4.6.2" href="#7.24.4.6.2">7.24.4.6.2 The wmemset function</a></h5>
<p><!--para 3 -->
The wcslen function returns the number of wide characters that precede the terminating
null wide character.
<h5><a name="7.24.4.6.2" href="#7.24.4.6.2">7.24.4.6.2 The wmemset function</a></h5>
<p><!--para 2 -->
The wmemset function copies the value of c into each of the first n wide characters of
the object pointed to by s.
<p><!--para 2 -->
The wmemset function copies the value of c into each of the first n wide characters of
the object pointed to by s.
<p><!--para 3 -->
The wmemset function returns the value of s.
<h4><a name="7.24.5" href="#7.24.5">7.24.5 Wide character time conversion functions</a></h4>
<h5><a name="7.24.5.1" href="#7.24.5.1">7.24.5.1 The wcsftime function</a></h5>
<p><!--para 3 -->
The wmemset function returns the value of s.
<h4><a name="7.24.5" href="#7.24.5">7.24.5 Wide character time conversion functions</a></h4>
<h5><a name="7.24.5.1" href="#7.24.5.1">7.24.5.1 The wcsftime function</a></h5>
size_t wcsftime(wchar_t * restrict s,
size_t maxsize,
const wchar_t * restrict format,
size_t wcsftime(wchar_t * restrict s,
size_t maxsize,
const wchar_t * restrict format,
corresponding sequences of wide characters.
<li> The return value indicates the number of wide characters.
</ul>
corresponding sequences of wide characters.
<li> The return value indicates the number of wide characters.
</ul>
<p><!--para 3 -->
If the total number of resulting wide characters including the terminating null wide
character is not more than maxsize, the wcsftime function returns the number of
<p><!--para 3 -->
If the total number of resulting wide characters including the terminating null wide
character is not more than maxsize, the wcsftime function returns the number of
<p><small><a name="note299" href="#note299">299)</a> 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.
<p><small><a name="note299" href="#note299">299)</a> 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.
<h5><a name="7.24.6.1" href="#7.24.6.1">7.24.6.1 Single-byte/wide character conversion functions</a></h5>
<h5><a name="7.24.6.1.1" href="#7.24.6.1.1">7.24.6.1.1 The btowc function</a></h5>
<h5><a name="7.24.6.1" href="#7.24.6.1">7.24.6.1 Single-byte/wide character conversion functions</a></h5>
<h5><a name="7.24.6.1.1" href="#7.24.6.1.1">7.24.6.1.1 The btowc function</a></h5>
<p><!--para 3 -->
The btowc function returns WEOF if c has the value EOF or if (unsigned char)c
does not constitute a valid single-byte character in the initial shift state. Otherwise, it
returns the wide character representation of that character.
<h5><a name="7.24.6.1.2" href="#7.24.6.1.2">7.24.6.1.2 The wctob function</a></h5>
<p><!--para 3 -->
The btowc function returns WEOF if c has the value EOF or if (unsigned char)c
does not constitute a valid single-byte character in the initial shift state. Otherwise, it
returns the wide character representation of that character.
<h5><a name="7.24.6.1.2" href="#7.24.6.1.2">7.24.6.1.2 The wctob function</a></h5>
<p><!--para 2 -->
The wctob function determines whether c corresponds to a member of the extended
character set whose multibyte character representation is a single byte when in the initial
shift state.
<p><!--para 2 -->
The wctob function determines whether c corresponds to a member of the extended
character set whose multibyte character representation is a single byte when in the initial
shift state.
<p><!--para 3 -->
The wctob function returns EOF if c does not correspond to a multibyte character with
length one in the initial shift state. Otherwise, it returns the single-byte representation of
<p><!--para 3 -->
The wctob function returns EOF if c does not correspond to a multibyte character with
length one in the initial shift state. Otherwise, it returns the single-byte representation of
<h5><a name="7.24.6.2" href="#7.24.6.2">7.24.6.2 Conversion state functions</a></h5>
<h5><a name="7.24.6.2.1" href="#7.24.6.2.1">7.24.6.2.1 The mbsinit function</a></h5>
<h5><a name="7.24.6.2" href="#7.24.6.2">7.24.6.2 Conversion state functions</a></h5>
<h5><a name="7.24.6.2.1" href="#7.24.6.2.1">7.24.6.2.1 The mbsinit function</a></h5>
<p><!--para 2 -->
If ps is not a null pointer, the mbsinit function determines whether the pointed-to
mbstate_t object describes an initial conversion state.
<!--page 400 -->
<p><!--para 2 -->
If ps is not a null pointer, the mbsinit function determines whether the pointed-to
mbstate_t object describes an initial conversion state.
<!--page 400 -->
<p><!--para 3 -->
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.
<p><!--para 3 -->
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.
encoding is state-dependent.
<h5><a name="7.24.6.3.1" href="#7.24.6.3.1">7.24.6.3.1 The mbrlen function</a></h5>
encoding is state-dependent.
<h5><a name="7.24.6.3.1" href="#7.24.6.3.1">7.24.6.3.1 The mbrlen function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrlen(const char * restrict s,
size_t n,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrlen(const char * restrict s,
size_t n,
- mbrtowc(NULL, s, n, ps != NULL ? ps : &internal)</pre>
+ mbrtowc(NULL, s, n, ps != NULL ? ps : &internal)
+</pre>
where internal is the mbstate_t object for the mbrlen function, except that the
expression designated by ps is evaluated only once.
where internal is the mbstate_t object for the mbrlen function, except that the
expression designated by ps is evaluated only once.
<p><!--para 3 -->
The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2),
or (size_t)(-1).
<p><!--para 3 -->
The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2),
or (size_t)(-1).
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrtowc(wchar_t * restrict pwc,
const char * restrict s,
size_t n,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrtowc(wchar_t * restrict pwc,
const char * restrict s,
size_t n,
- mbrtowc(NULL, "", 1, ps)</pre>
+ mbrtowc(NULL, "", 1, ps)
+</pre>
In this case, the values of the parameters pwc and n are ignored.
<p><!--para 3 -->
If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with
In this case, the values of the parameters pwc and n are ignored.
<p><!--para 3 -->
If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with
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.
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.
<p><small><a name="note300" href="#note300">300)</a> 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).
</small>
<h5><a name="7.24.6.3.3" href="#7.24.6.3.3">7.24.6.3.3 The wcrtomb function</a></h5>
<p><small><a name="note300" href="#note300">300)</a> 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).
</small>
<h5><a name="7.24.6.3.3" href="#7.24.6.3.3">7.24.6.3.3 The wcrtomb function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcrtomb(char * restrict s,
wchar_t wc,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcrtomb(char * restrict s,
wchar_t wc,
where buf is an internal buffer.
<p><!--para 3 -->
If s is not a null pointer, the wcrtomb function determines the number of bytes needed
where buf is an internal buffer.
<p><!--para 3 -->
If s is not a null pointer, the wcrtomb function determines the number of bytes needed
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.
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.
<p><!--para 4 -->
The wcrtomb function returns the number of bytes stored in the array object (including
any shift sequences). When wc is not a valid wide character, an encoding error occurs:
<p><!--para 4 -->
The wcrtomb function returns the number of bytes stored in the array object (including
any shift sequences). When wc is not a valid wide character, an encoding error occurs:
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbsrtowcs(wchar_t * restrict dst,
const char ** restrict src,
size_t len,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbsrtowcs(wchar_t * restrict dst,
const char ** restrict src,
size_t len,
<p><!--para 2 -->
The mbsrtowcs function converts a sequence of multibyte characters that begins in the
conversion state described by the object pointed to by ps, from the array indirectly
<p><!--para 2 -->
The mbsrtowcs function converts a sequence of multibyte characters that begins in the
conversion state described by the object pointed to by ps, from the array indirectly
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.
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.
<p><!--para 4 -->
If the input conversion encounters a sequence of bytes that do not form a valid multibyte
character, an encoding error occurs: the mbsrtowcs function stores the value of the
<p><!--para 4 -->
If the input conversion encounters a sequence of bytes that do not form a valid multibyte
character, an encoding error occurs: the mbsrtowcs function stores the value of the
<p><small><a name="note301" href="#note301">301)</a> Thus, the value of len is ignored if dst is a null pointer.
</small>
<h5><a name="7.24.6.4.2" href="#7.24.6.4.2">7.24.6.4.2 The wcsrtombs function</a></h5>
<p><small><a name="note301" href="#note301">301)</a> Thus, the value of len is ignored if dst is a null pointer.
</small>
<h5><a name="7.24.6.4.2" href="#7.24.6.4.2">7.24.6.4.2 The wcsrtombs function</a></h5>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src,
size_t len,
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src,
size_t len,
<p><!--para 2 -->
The wcsrtombs function converts a sequence of wide characters from the array
indirectly pointed to by src into a sequence of corresponding multibyte characters that
<p><!--para 2 -->
The wcsrtombs function converts a sequence of wide characters from the array
indirectly pointed to by src into a sequence of corresponding multibyte characters that
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.
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.
<p><!--para 4 -->
If conversion stops because a wide character is reached that does not correspond to a
valid multibyte character, an encoding error occurs: the wcsrtombs function stores the
<p><!--para 4 -->
If conversion stops because a wide character is reached that does not correspond to a
valid multibyte character, an encoding error occurs: the wcsrtombs function stores the
<p><small><a name="note302" href="#note302">302)</a> 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.
</small>
<p><small><a name="note302" href="#note302">302)</a> 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.
</small>
both printing and white-space wide characters.<sup><a href="#note304"><b>304)</b></a></sup>
<p><b> Forward references</b>: the wctob function (<a href="#7.24.6.1.2">7.24.6.1.2</a>).
both printing and white-space wide characters.<sup><a href="#note304"><b>304)</b></a></sup>
<p><b> Forward references</b>: the wctob function (<a href="#7.24.6.1.2">7.24.6.1.2</a>).
<p><small><a name="note304" href="#note304">304)</a> 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)
<p><small><a name="note304" href="#note304">304)</a> 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)
<p><!--para 2 -->
The iswalnum function tests for any wide character for which iswalpha or
iswdigit is true.
<h5><a name="7.25.2.1.2" href="#7.25.2.1.2">7.25.2.1.2 The iswalpha function</a></h5>
<p><!--para 2 -->
The iswalnum function tests for any wide character for which iswalpha or
iswdigit is true.
<h5><a name="7.25.2.1.2" href="#7.25.2.1.2">7.25.2.1.2 The iswalpha function</a></h5>
<p><!--para 2 -->
The iswalpha function tests for any wide character for which iswupper or
iswlower is true, or any wide character that is one of a locale-specific set of alphabetic
<p><!--para 2 -->
The iswalpha function tests for any wide character for which iswupper or
iswlower is true, or any wide character that is one of a locale-specific set of alphabetic
wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace
is true.<sup><a href="#note305"><b>305)</b></a></sup>
wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace
is true.<sup><a href="#note305"><b>305)</b></a></sup>
<p><small><a name="note305" href="#note305">305)</a> The functions iswlower and iswupper test true or false separately for each of these additional
wide characters; all four combinations are possible.
</small>
<h5><a name="7.25.2.1.3" href="#7.25.2.1.3">7.25.2.1.3 The iswblank function</a></h5>
<p><small><a name="note305" href="#note305">305)</a> The functions iswlower and iswupper test true or false separately for each of these additional
wide characters; all four combinations are possible.
</small>
<h5><a name="7.25.2.1.3" href="#7.25.2.1.3">7.25.2.1.3 The iswblank function</a></h5>
<p><!--para 2 -->
The iswblank function tests for any wide character that is a standard blank wide
character or is one of a locale-specific set of wide characters for which iswspace is true
<p><!--para 2 -->
The iswblank function tests for any wide character that is a standard blank wide
character or is one of a locale-specific set of wide characters for which iswspace is true
locale, iswblank returns true only for the standard blank characters.
<h5><a name="7.25.2.1.4" href="#7.25.2.1.4">7.25.2.1.4 The iswcntrl function</a></h5>
locale, iswblank returns true only for the standard blank characters.
<h5><a name="7.25.2.1.4" href="#7.25.2.1.4">7.25.2.1.4 The iswcntrl function</a></h5>
<p><!--para 2 -->
The iswcntrl function tests for any control wide character.
<h5><a name="7.25.2.1.5" href="#7.25.2.1.5">7.25.2.1.5 The iswdigit function</a></h5>
<p><!--para 2 -->
The iswcntrl function tests for any control wide character.
<h5><a name="7.25.2.1.5" href="#7.25.2.1.5">7.25.2.1.5 The iswdigit function</a></h5>
<p><!--para 2 -->
The iswdigit function tests for any wide character that corresponds to a decimal-digit
character (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.25.2.1.6" href="#7.25.2.1.6">7.25.2.1.6 The iswgraph function</a></h5>
<p><!--para 2 -->
The iswdigit function tests for any wide character that corresponds to a decimal-digit
character (as defined in <a href="#5.2.1">5.2.1</a>).
<h5><a name="7.25.2.1.6" href="#7.25.2.1.6">7.25.2.1.6 The iswgraph function</a></h5>
<p><!--para 2 -->
The iswgraph function tests for any wide character for which iswprint is true and
iswspace is false.<sup><a href="#note306"><b>306)</b></a></sup>
<p><!--para 2 -->
The iswgraph function tests for any wide character for which iswprint is true and
iswspace is false.<sup><a href="#note306"><b>306)</b></a></sup>
<p><small><a name="note306" href="#note306">306)</a> Note that the behavior of the iswgraph and iswpunct functions may differ from their
corresponding functions in <a href="#7.4.1">7.4.1</a> with respect to printing, white-space, single-byte execution
characters other than ' '.
</small>
<h5><a name="7.25.2.1.7" href="#7.25.2.1.7">7.25.2.1.7 The iswlower function</a></h5>
<p><small><a name="note306" href="#note306">306)</a> Note that the behavior of the iswgraph and iswpunct functions may differ from their
corresponding functions in <a href="#7.4.1">7.4.1</a> with respect to printing, white-space, single-byte execution
characters other than ' '.
</small>
<h5><a name="7.25.2.1.7" href="#7.25.2.1.7">7.25.2.1.7 The iswlower function</a></h5>
<p><!--para 2 -->
The iswlower function tests for any wide character that corresponds to a lowercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<h5><a name="7.25.2.1.8" href="#7.25.2.1.8">7.25.2.1.8 The iswprint function</a></h5>
<p><!--para 2 -->
The iswlower function tests for any wide character that corresponds to a lowercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<h5><a name="7.25.2.1.8" href="#7.25.2.1.8">7.25.2.1.8 The iswprint function</a></h5>
<p><!--para 2 -->
The iswprint function tests for any printing wide character.
<h5><a name="7.25.2.1.9" href="#7.25.2.1.9">7.25.2.1.9 The iswpunct function</a></h5>
<p><!--para 2 -->
The iswprint function tests for any printing wide character.
<h5><a name="7.25.2.1.9" href="#7.25.2.1.9">7.25.2.1.9 The iswpunct function</a></h5>
<p><!--para 2 -->
The iswpunct function tests for any printing wide character that is one of a locale-
specific set of punctuation wide characters for which neither iswspace nor iswalnum
<p><!--para 2 -->
The iswpunct function tests for any printing wide character that is one of a locale-
specific set of punctuation wide characters for which neither iswspace nor iswalnum
<p><!--para 2 -->
The iswspace function tests for any wide character that corresponds to a locale-specific
set of white-space wide characters for which none of iswalnum, iswgraph, or
iswpunct is true.
<h5><a name="7.25.2.1.11" href="#7.25.2.1.11">7.25.2.1.11 The iswupper function</a></h5>
<p><!--para 2 -->
The iswspace function tests for any wide character that corresponds to a locale-specific
set of white-space wide characters for which none of iswalnum, iswgraph, or
iswpunct is true.
<h5><a name="7.25.2.1.11" href="#7.25.2.1.11">7.25.2.1.11 The iswupper function</a></h5>
<p><!--para 2 -->
The iswupper function tests for any wide character that corresponds to an uppercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<h5><a name="7.25.2.1.12" href="#7.25.2.1.12">7.25.2.1.12 The iswxdigit function</a></h5>
<p><!--para 2 -->
The iswupper function tests for any wide character that corresponds to an uppercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<h5><a name="7.25.2.1.12" href="#7.25.2.1.12">7.25.2.1.12 The iswxdigit function</a></h5>
<p><!--para 2 -->
The iswxdigit function tests for any wide character that corresponds to a
hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<p><!--para 2 -->
The iswxdigit function tests for any wide character that corresponds to a
hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
subclause (<a href="#7.25.2.1">7.25.2.1</a>).
<h5><a name="7.25.2.2.1" href="#7.25.2.2.1">7.25.2.2.1 The iswctype function</a></h5>
subclause (<a href="#7.25.2.1">7.25.2.1</a>).
<h5><a name="7.25.2.2.1" href="#7.25.2.2.1">7.25.2.2.1 The iswctype function</a></h5>
<p><!--para 2 -->
The iswctype function determines whether the wide character wc has the property
described by desc. The current setting of the LC_CTYPE category shall be the same as
<p><!--para 2 -->
The iswctype function determines whether the wide character wc has the property
described by desc. The current setting of the LC_CTYPE category shall be the same as
iswctype(wc, wctype("punct")) // iswpunct(wc)
iswctype(wc, wctype("space")) // iswspace(wc)
iswctype(wc, wctype("upper")) // iswupper(wc)
iswctype(wc, wctype("punct")) // iswpunct(wc)
iswctype(wc, wctype("space")) // iswspace(wc)
iswctype(wc, wctype("upper")) // iswupper(wc)
<p><!--para 4 -->
The iswctype function returns nonzero (true) if and only if the value of the wide
character wc has the property described by desc.
<p><b> Forward references</b>: the wctype function (<a href="#7.25.2.2.2">7.25.2.2.2</a>).
<h5><a name="7.25.2.2.2" href="#7.25.2.2.2">7.25.2.2.2 The wctype function</a></h5>
<p><!--para 4 -->
The iswctype function returns nonzero (true) if and only if the value of the wide
character wc has the property described by desc.
<p><b> Forward references</b>: the wctype function (<a href="#7.25.2.2.2">7.25.2.2.2</a>).
<h5><a name="7.25.2.2.2" href="#7.25.2.2.2">7.25.2.2.2 The wctype function</a></h5>
<p><!--para 2 -->
The wctype function constructs a value with type wctype_t that describes a class of
wide characters identified by the string argument property.
<p><!--para 3 -->
The strings listed in the description of the iswctype function shall be valid in all
locales as property arguments to the wctype function.
<p><!--para 2 -->
The wctype function constructs a value with type wctype_t that describes a class of
wide characters identified by the string argument property.
<p><!--para 3 -->
The strings listed in the description of the iswctype function shall be valid in all
locales as property arguments to the wctype function.
<p><!--para 4 -->
If property identifies a valid class of wide characters according to the LC_CTYPE
category of the current locale, the wctype function returns a nonzero value that is valid
<p><!--para 4 -->
If property identifies a valid class of wide characters according to the LC_CTYPE
category of the current locale, the wctype function returns a nonzero value that is valid
<h5><a name="7.25.3.1" href="#7.25.3.1">7.25.3.1 Wide character case mapping functions</a></h5>
<h5><a name="7.25.3.1.1" href="#7.25.3.1.1">7.25.3.1.1 The towlower function</a></h5>
<h5><a name="7.25.3.1" href="#7.25.3.1">7.25.3.1 Wide character case mapping functions</a></h5>
<h5><a name="7.25.3.1.1" href="#7.25.3.1.1">7.25.3.1.1 The towlower function</a></h5>
<p><!--para 3 -->
If the argument is a wide character for which iswupper is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
<p><!--para 3 -->
If the argument is a wide character for which iswupper is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
<p><!--para 3 -->
If the argument is a wide character for which iswlower is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
<p><!--para 3 -->
If the argument is a wide character for which iswlower is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
<p><!--para 2 -->
The towctrans function maps the wide character wc using the mapping described by
desc. The current setting of the LC_CTYPE category shall be the same as during the call
<p><!--para 2 -->
The towctrans function maps the wide character wc using the mapping described by
desc. The current setting of the LC_CTYPE category shall be the same as during the call
mapping function (<a href="#7.25.3.1">7.25.3.1</a>) in the comment that follows the expression:
<pre>
towctrans(wc, wctrans("tolower")) // towlower(wc)
mapping function (<a href="#7.25.3.1">7.25.3.1</a>) in the comment that follows the expression:
<pre>
towctrans(wc, wctrans("tolower")) // towlower(wc)
<p><!--para 4 -->
The towctrans function returns the mapped value of wc using the mapping described
by desc.
<h5><a name="7.25.3.2.2" href="#7.25.3.2.2">7.25.3.2.2 The wctrans function</a></h5>
<p><!--para 4 -->
The towctrans function returns the mapped value of wc using the mapping described
by desc.
<h5><a name="7.25.3.2.2" href="#7.25.3.2.2">7.25.3.2.2 The wctrans function</a></h5>
<p><!--para 2 -->
The wctrans function constructs a value with type wctrans_t that describes a
mapping between wide characters identified by the string argument property.
<p><!--para 3 -->
The strings listed in the description of the towctrans function shall be valid in all
locales as property arguments to the wctrans function.
<p><!--para 2 -->
The wctrans function constructs a value with type wctrans_t that describes a
mapping between wide characters identified by the string argument property.
<p><!--para 3 -->
The strings listed in the description of the towctrans function shall be valid in all
locales as property arguments to the wctrans function.
<p><!--para 4 -->
If property identifies a valid mapping of wide characters according to the LC_CTYPE
category of the current locale, the wctrans function returns a nonzero value that is valid
<p><!--para 4 -->
If property identifies a valid mapping of wide characters according to the LC_CTYPE
category of the current locale, the wctrans function returns a nonzero value that is valid
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.
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.
and the same names suffixed with f or l may be added to the declarations in the
<a href="#7.3"><complex.h></a> header.
and the same names suffixed with f or l may be added to the declarations in the
<a href="#7.3"><complex.h></a> header.
<p><!--para 1 -->
Function names that begin with either is or to, and a lowercase letter may be added to
the declarations in the <a href="#7.4"><ctype.h></a> header.
<p><!--para 1 -->
Function names that begin with either is or to, and a lowercase letter may be added to
the declarations in the <a href="#7.4"><ctype.h></a> header.
<p><!--para 1 -->
Macros that begin with E and a digit or E and an uppercase letter may be added to the
declarations in the <a href="#7.5"><errno.h></a> header.
<p><!--para 1 -->
Macros that begin with E and a digit or E and an uppercase letter may be added to the
declarations in the <a href="#7.5"><errno.h></a> header.
<p><!--para 1 -->
Macro names beginning with PRI or SCN followed by any lowercase letter or X may be
added to the macros defined in the <a href="#7.8"><inttypes.h></a> header.
<p><!--para 1 -->
Macro names beginning with PRI or SCN followed by any lowercase letter or X may be
added to the macros defined in the <a href="#7.8"><inttypes.h></a> header.
<p><!--para 1 -->
Macros that begin with LC_ and an uppercase letter may be added to the definitions in
the <a href="#7.11"><locale.h></a> header.
<p><!--para 1 -->
Macros that begin with LC_ and an uppercase letter may be added to the definitions in
the <a href="#7.11"><locale.h></a> header.
<p><!--para 1 -->
Macros that begin with either SIG and an uppercase letter or SIG_ and an uppercase
letter may be added to the definitions in the <a href="#7.14"><signal.h></a> header.
<p><!--para 1 -->
Macros that begin with either SIG and an uppercase letter or SIG_ and an uppercase
letter may be added to the definitions in the <a href="#7.14"><signal.h></a> header.
<p><!--para 1 -->
Typedef names beginning with int or uint and ending with _t may be added to the
types defined in the <a href="#7.18"><stdint.h></a> header. Macro names beginning with INT or UINT
<p><!--para 1 -->
Typedef names beginning with int or uint and ending with _t may be added to the
types defined in the <a href="#7.18"><stdint.h></a> header. Macro names beginning with INT or UINT
<p><!--para 1 -->
Lowercase letters may be added to the conversion specifiers and length modifiers in
fprintf and fscanf. Other characters may be used in extensions.
<p><!--para 1 -->
Lowercase letters may be added to the conversion specifiers and length modifiers in
fprintf and fscanf. Other characters may be used in extensions.
The use of ungetc on a binary stream where the file position indicator is zero prior to
the call is an obsolescent feature.
The use of ungetc on a binary stream where the file position indicator is zero prior to
the call is an obsolescent feature.
<p><!--para 1 -->
Function names that begin with str and a lowercase letter may be added to the
declarations in the <a href="#7.20"><stdlib.h></a> header.
<p><!--para 1 -->
Function names that begin with str and a lowercase letter may be added to the
declarations in the <a href="#7.20"><stdlib.h></a> header.
<p><!--para 1 -->
Function names that begin with str, mem, or wcs and a lowercase letter may be added
to the declarations in the <a href="#7.21"><string.h></a> header.
<p><!--para 1 -->
Function names that begin with str, mem, or wcs and a lowercase letter may be added
to the declarations in the <a href="#7.21"><string.h></a> header.
<p><!--para 1 -->
Function names that begin with wcs and a lowercase letter may be added to the
declarations in the <a href="#7.24"><wchar.h></a> header.
<p><!--para 1 -->
Function names that begin with wcs and a lowercase letter may be added to the
declarations in the <a href="#7.24"><wchar.h></a> header.
<h4><a name="A.1.2" href="#A.1.2">A.1.2 Keywords</a></h4>
(<a href="#6.4.1">6.4.1</a>) keyword: one of
<h4><a name="A.1.2" href="#A.1.2">A.1.2 Keywords</a></h4>
(<a href="#6.4.1">6.4.1</a>) keyword: one of
<h4><a name="A.1.3" href="#A.1.3">A.1.3 Identifiers</a></h4>
(<a href="#6.4.2.1">6.4.2.1</a>) identifier:
<pre>
identifier-nondigit
identifier identifier-nondigit
<h4><a name="A.1.3" href="#A.1.3">A.1.3 Identifiers</a></h4>
(<a href="#6.4.2.1">6.4.2.1</a>) identifier:
<pre>
identifier-nondigit
identifier identifier-nondigit
(<a href="#6.4.2.1">6.4.2.1</a>) nondigit: one of
<pre>
_ a b c d e f g h i j k l m
n o p q r s t u v w x y z
A B C D E F G H I J K L M
(<a href="#6.4.2.1">6.4.2.1</a>) nondigit: one of
<pre>
_ a b c d e f g h i j k l m
n o p q r s t u v w x y z
A B C D E F G H I J K L M
<h4><a name="A.1.4" href="#A.1.4">A.1.4 Universal character names</a></h4>
(<a href="#6.4.3">6.4.3</a>) universal-character-name:
<pre>
\u hex-quad
<h4><a name="A.1.4" href="#A.1.4">A.1.4 Universal character names</a></h4>
(<a href="#6.4.3">6.4.3</a>) universal-character-name:
<pre>
\u hex-quad
- decimal-constant integer-suffixopt
- octal-constant integer-suffixopt
- hexadecimal-constant integer-suffixopt</pre>
+ decimal-constant integer-suffix<sub>opt</sub>
+ octal-constant integer-suffix<sub>opt</sub>
+ hexadecimal-constant integer-suffix<sub>opt</sub>
+</pre>
- fractional-constant exponent-partopt floating-suffixopt
- digit-sequence exponent-part floating-suffixopt</pre>
+ fractional-constant exponent-part<sub>opt</sub> floating-suffix<sub>opt</sub>
+ digit-sequence exponent-part floating-suffix<sub>opt</sub>
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) hexadecimal-floating-constant:
<pre>
hexadecimal-prefix hexadecimal-fractional-constant
(<a href="#6.4.4.2">6.4.4.2</a>) hexadecimal-floating-constant:
<pre>
hexadecimal-prefix hexadecimal-fractional-constant
(<a href="#6.4.4.4">6.4.4.4</a>) c-char:
<pre>
any member of the source character set except
the single-quote ', backslash \, or new-line character
(<a href="#6.4.4.4">6.4.4.4</a>) c-char:
<pre>
any member of the source character set except
the single-quote ', backslash \, or new-line character
<h4><a name="A.1.6" href="#A.1.6">A.1.6 String literals</a></h4>
(<a href="#6.4.5">6.4.5</a>) string-literal:
<pre>
<h4><a name="A.1.6" href="#A.1.6">A.1.6 String literals</a></h4>
(<a href="#6.4.5">6.4.5</a>) string-literal:
<pre>
(<a href="#6.4.5">6.4.5</a>) s-char:
<!--page 420 -->
<pre>
any member of the source character set except
the double-quote ", backslash \, or new-line character
(<a href="#6.4.5">6.4.5</a>) s-char:
<!--page 420 -->
<pre>
any member of the source character set except
the double-quote ", backslash \, or new-line character
<h4><a name="A.1.7" href="#A.1.7">A.1.7 Punctuators</a></h4>
(<a href="#6.4.6">6.4.6</a>) punctuator: one of
<h4><a name="A.1.7" href="#A.1.7">A.1.7 Punctuators</a></h4>
(<a href="#6.4.6">6.4.6</a>) punctuator: one of
<h4><a name="A.1.8" href="#A.1.8">A.1.8 Header names</a></h4>
(<a href="#6.4.7">6.4.7</a>) header-name:
<pre>
< h-char-sequence >
<h4><a name="A.1.8" href="#A.1.8">A.1.8 Header names</a></h4>
(<a href="#6.4.7">6.4.7</a>) header-name:
<pre>
< h-char-sequence >
<h4><a name="A.1.9" href="#A.1.9">A.1.9 Preprocessing numbers</a></h4>
(<a href="#6.4.8">6.4.8</a>) pp-number:
<h4><a name="A.1.9" href="#A.1.9">A.1.9 Preprocessing numbers</a></h4>
(<a href="#6.4.8">6.4.8</a>) pp-number:
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
(<a href="#6.5.5">6.5.5</a>) multiplicative-expression:
<!--page 422 -->
<pre>
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
(<a href="#6.5.5">6.5.5</a>) multiplicative-expression:
<!--page 422 -->
<pre>
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
(<a href="#6.5.6">6.5.6</a>) additive-expression:
<pre>
multiplicative-expression
additive-expression + multiplicative-expression
(<a href="#6.5.6">6.5.6</a>) additive-expression:
<pre>
multiplicative-expression
additive-expression + multiplicative-expression
(<a href="#6.5.8">6.5.8</a>) relational-expression:
<pre>
shift-expression
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
(<a href="#6.5.8">6.5.8</a>) relational-expression:
<pre>
shift-expression
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
- storage-class-specifier declaration-specifiersopt
- type-specifier declaration-specifiersopt
- type-qualifier declaration-specifiersopt
- function-specifier declaration-specifiersopt</pre>
+ storage-class-specifier declaration-specifiers<sub>opt</sub>
+ type-specifier declaration-specifiers<sub>opt</sub>
+ type-qualifier declaration-specifiers<sub>opt</sub>
+ function-specifier declaration-specifiers<sub>opt</sub>
+</pre>
- type-specifier specifier-qualifier-listopt
- type-qualifier specifier-qualifier-listopt</pre>
+ type-specifier specifier-qualifier-list<sub>opt</sub>
+ type-qualifier specifier-qualifier-list<sub>opt</sub>
+</pre>
- enum identifieropt { enumerator-list }
- enum identifieropt { enumerator-list , }
- enum identifier</pre>
+ enum identifier<sub>opt</sub> { enumerator-list }
+ enum identifier<sub>opt</sub> { enumerator-list , }
+ enum identifier
+</pre>
- direct-declarator [ type-qualifier-listopt assignment-expressionopt ]
- direct-declarator [ static type-qualifier-listopt assignment-expression ]
+ direct-declarator [ type-qualifier-list<sub>opt</sub> assignment-expression<sub>opt</sub> ]
+ direct-declarator [ static type-qualifier-list<sub>opt</sub> assignment-expression ]
- direct-abstract-declaratoropt [ type-qualifier-listopt
- assignment-expressionopt ]
- direct-abstract-declaratoropt [ static type-qualifier-listopt
+ direct-abstract-declarator<sub>opt</sub> [ type-qualifier-list<sub>opt</sub>
+ assignment-expression<sub>opt</sub> ]
+ direct-abstract-declarator<sub>opt</sub> [ static type-qualifier-list<sub>opt</sub>
- direct-abstract-declaratoropt [ * ]
- direct-abstract-declaratoropt ( parameter-type-listopt )</pre>
+ direct-abstract-declarator<sub>opt</sub> [ * ]
+ direct-abstract-declarator<sub>opt</sub> ( parameter-type-list<sub>opt</sub> )
+</pre>
- designationopt initializer
- initializer-list , designationopt initializer</pre>
+ designation<sub>opt</sub> initializer
+ initializer-list , designation<sub>opt</sub> initializer
+</pre>
(<a href="#6.8.4">6.8.4</a>) selection-statement:
<!--page 428 -->
<pre>
if ( expression ) statement
if ( expression ) statement else statement
(<a href="#6.8.4">6.8.4</a>) selection-statement:
<!--page 428 -->
<pre>
if ( expression ) statement
if ( expression ) statement else statement
(<a href="#6.8.5">6.8.5</a>) iteration-statement:
<pre>
while ( expression ) statement
do statement while ( expression ) ;
(<a href="#6.8.5">6.8.5</a>) iteration-statement:
<pre>
while ( expression ) statement
do statement while ( expression ) ;
- for ( expressionopt ; expressionopt ; expressionopt ) statement
- for ( declaration expressionopt ; expressionopt ) statement</pre>
+ for ( expression<sub>opt</sub> ; expression<sub>opt</sub> ; expression<sub>opt</sub> ) statement
+ for ( declaration expression<sub>opt</sub> ; expression<sub>opt</sub> ) statement
+</pre>
<h4><a name="A.2.4" href="#A.2.4">A.2.4 External definitions</a></h4>
(<a href="#6.9">6.9</a>) translation-unit:
<pre>
external-declaration
<h4><a name="A.2.4" href="#A.2.4">A.2.4 External definitions</a></h4>
(<a href="#6.9">6.9</a>) translation-unit:
<pre>
external-declaration
<h3><a name="A.3" href="#A.3">A.3 Preprocessing directives</a></h3>
(<a href="#6.10">6.10</a>) preprocessing-file:
<pre>
<h3><a name="A.3" href="#A.3">A.3 Preprocessing directives</a></h3>
(<a href="#6.10">6.10</a>) preprocessing-file:
<pre>
- # if constant-expression new-line groupopt
- # ifdef identifier new-line groupopt
- # ifndef identifier new-line groupopt</pre>
+ # if constant-expression new-line group<sub>opt</sub>
+ # ifdef identifier new-line group<sub>opt</sub>
+ # ifndef identifier new-line group<sub>opt</sub>
+</pre>
(<a href="#6.10">6.10</a>) control-line:
<pre>
# include pp-tokens new-line
# define identifier replacement-list new-line
(<a href="#6.10">6.10</a>) control-line:
<pre>
# include pp-tokens new-line
# define identifier replacement-list new-line
replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
# define identifier lparen identifier-list , ... )
replacement-list new-line
# undef identifier new-line
# line pp-tokens new-line
replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
# define identifier lparen identifier-list , ... )
replacement-list new-line
# undef identifier new-line
# line pp-tokens new-line
long double complex cprojl(long double complex z);
double creal(double complex z);
float crealf(float complex z);
long double complex cprojl(long double complex z);
double creal(double complex z);
float crealf(float complex z);
int fegetenv(fenv_t *envp);
int feholdexcept(fenv_t *envp);
int fesetenv(const fenv_t *envp);
int fegetenv(fenv_t *envp);
int feholdexcept(fenv_t *envp);
int fesetenv(const fenv_t *envp);
intmax_t wcstoimax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
uintmax_t wcstoumax(const wchar_t * restrict nptr,
intmax_t wcstoimax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
uintmax_t wcstoumax(const wchar_t * restrict nptr,
<pre>
CHAR_BIT CHAR_MAX INT_MIN ULONG_MAX
SCHAR_MIN MB_LEN_MAX INT_MAX LLONG_MIN
SCHAR_MAX SHRT_MIN UINT_MAX LLONG_MAX
UCHAR_MAX SHRT_MAX LONG_MIN ULLONG_MAX
<pre>
CHAR_BIT CHAR_MAX INT_MIN ULONG_MAX
SCHAR_MIN MB_LEN_MAX INT_MAX LLONG_MIN
SCHAR_MAX SHRT_MIN UINT_MAX LLONG_MAX
UCHAR_MAX SHRT_MAX LONG_MIN ULLONG_MAX
<pre>
struct lconv LC_ALL LC_CTYPE LC_NUMERIC
NULL LC_COLLATE LC_MONETARY LC_TIME
char *setlocale(int category, const char *locale);
<pre>
struct lconv LC_ALL LC_CTYPE LC_NUMERIC
NULL LC_COLLATE LC_MONETARY LC_TIME
char *setlocale(int category, const char *locale);
int isless(real-floating x, real-floating y);
int islessequal(real-floating x, real-floating y);
int islessgreater(real-floating x, real-floating y);
int isless(real-floating x, real-floating y);
int islessequal(real-floating x, real-floating y);
int islessgreater(real-floating x, real-floating y);
<pre>
sig_atomic_t SIG_IGN SIGILL SIGTERM
SIG_DFL SIGABRT SIGINT
SIG_ERR SIGFPE SIGSEGV
void (*signal(int sig, void (*func)(int)))(int);
<pre>
sig_atomic_t SIG_IGN SIGILL SIGTERM
SIG_DFL SIGABRT SIGINT
SIG_ERR SIGFPE SIGSEGV
void (*signal(int sig, void (*func)(int)))(int);
<pre>
va_list
type va_arg(va_list ap, type);
void va_copy(va_list dest, va_list src);
void va_end(va_list ap);
<pre>
va_list
type va_arg(va_list ap, type);
void va_copy(va_list dest, va_list src);
void va_end(va_list ap);
uintmax_t INTMAX_MIN UINTN_C(value)
INTN_MIN INTMAX_MAX INTMAX_C(value)
INTN_MAX UINTMAX_MAX UINTMAX_C(value)
uintmax_t INTMAX_MIN UINTN_C(value)
INTN_MIN INTMAX_MAX INTMAX_C(value)
INTN_MAX UINTMAX_MAX UINTMAX_C(value)
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s, size_t n);
size_t wcstombs(char * restrict s,
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s, size_t n);
size_t wcstombs(char * restrict s,
const char * restrict s2);
void *memset(void *s, int c, size_t n);
char *strerror(int errnum);
const char * restrict s2);
void *memset(void *s, int c, size_t n);
char *strerror(int errnum);
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
mbstate_t * restrict ps);
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src, size_t len,
mbstate_t * restrict ps);
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src, size_t len,
wint_t towlower(wint_t wc);
wint_t towupper(wint_t wc);
wint_t towctrans(wint_t wc, wctrans_t desc);
wint_t towlower(wint_t wc);
wint_t towupper(wint_t wc);
wint_t towctrans(wint_t wc, wctrans_t desc);
The following are the sequence points described in <a href="#5.1.2.3">5.1.2.3</a>:
<ul>
<li> The call to a function, after the arguments have been evaluated (<a href="#6.5.2.2">6.5.2.2</a>).
The following are the sequence points described in <a href="#5.1.2.3">5.1.2.3</a>:
<ul>
<li> The call to a function, after the arguments have been evaluated (<a href="#6.5.2.2">6.5.2.2</a>).
sets.
Latin: 00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217,
<pre>
sets.
Latin: 00AA, 00BA, 00C0-00D6, 00D8-00F6, 00F8-01F5, 01FA-0217,
<pre>
- 0250-02A8, 1E00-1E9B, 1EA0-1EF9, 207F</pre>
+ 0250-02A8, 1E00-1E9B, 1EA0-1EF9, 207F
+</pre>
Greek: 0386, 0388-038A, 038C, 038E-03A1, 03A3-03CE, 03D0-03D6,
<pre>
03DA, 03DC, 03DE, 03E0, 03E2-03F3, 1F00-1F15, 1F18-1F1D,
1F20-1F45, 1F48-1F4D, 1F50-1F57, 1F59, 1F5B, 1F5D,
1F5F-1F7D, 1F80-1FB4, 1FB6-1FBC, 1FC2-1FC4, 1FC6-1FCC,
Greek: 0386, 0388-038A, 038C, 038E-03A1, 03A3-03CE, 03D0-03D6,
<pre>
03DA, 03DC, 03DE, 03E0, 03E2-03F3, 1F00-1F15, 1F18-1F1D,
1F20-1F45, 1F48-1F4D, 1F50-1F57, 1F59, 1F5B, 1F5D,
1F5F-1F7D, 1F80-1FB4, 1FB6-1FBC, 1FC2-1FC4, 1FC6-1FCC,
- 1FD0-1FD3, 1FD6-1FDB, 1FE0-1FEC, 1FF2-1FF4, 1FF6-1FFC</pre>
+ 1FD0-1FD3, 1FD6-1FDB, 1FE0-1FEC, 1FF2-1FF4, 1FF6-1FFC
+</pre>
Cyrillic: 0401-040C, 040E-044F, 0451-045C, 045E-0481, 0490-04C4,
<pre>
Cyrillic: 0401-040C, 040E-044F, 0451-045C, 045E-0481, 0490-04C4,
<pre>
- 04C7-04C8, 04CB-04CC, 04D0-04EB, 04EE-04F5, 04F8-04F9</pre>
+ 04C7-04C8, 04CB-04CC, 04D0-04EB, 04EE-04F5, 04F8-04F9
+</pre>
Armenian: 0531-0556, 0561-0587
Hebrew: 05B0-05B9, 05BB-05BD, 05BF, 05C1-05C2, 05D0-05EA,
<pre>
Armenian: 0531-0556, 0561-0587
Hebrew: 05B0-05B9, 05BB-05BD, 05BF, 05C1-05C2, 05D0-05EA,
<pre>
Arabic: 0621-063A, 0640-0652, 0670-06B7, 06BA-06BE, 06C0-06CE,
<pre>
Arabic: 0621-063A, 0640-0652, 0670-06B7, 06BA-06BE, 06C0-06CE,
<pre>
Devanagari: 0901-0903, 0905-0939, 093E-094D, 0950-0952, 0958-0963
Bengali: 0981-0983, 0985-098C, 098F-0990, 0993-09A8, 09AA-09B0,
<pre>
09B2, 09B6-09B9, 09BE-09C4, 09C7-09C8, 09CB-09CD,
Devanagari: 0901-0903, 0905-0939, 093E-094D, 0950-0952, 0958-0963
Bengali: 0981-0983, 0985-098C, 098F-0990, 0993-09A8, 09AA-09B0,
<pre>
09B2, 09B6-09B9, 09BE-09C4, 09C7-09C8, 09CB-09CD,
Gurmukhi: 0A02, 0A05-0A0A, 0A0F-0A10, 0A13-0A28, 0A2A-0A30,
<pre>
0A32-0A33, 0A35-0A36, 0A38-0A39, 0A3E-0A42, 0A47-0A48,
Gurmukhi: 0A02, 0A05-0A0A, 0A0F-0A10, 0A13-0A28, 0A2A-0A30,
<pre>
0A32-0A33, 0A35-0A36, 0A38-0A39, 0A3E-0A42, 0A47-0A48,
- 0A4B-0A4D, 0A59-0A5C, 0A5E, 0A74</pre>
+ 0A4B-0A4D, 0A59-0A5C, 0A5E, 0A74
+</pre>
Gujarati: 0A81-0A83, 0A85-0A8B, 0A8D, 0A8F-0A91, 0A93-0AA8,
<pre>
0AAA-0AB0, 0AB2-0AB3, 0AB5-0AB9, 0ABD-0AC5,
Gujarati: 0A81-0A83, 0A85-0A8B, 0A8D, 0A8F-0A91, 0A93-0AA8,
<pre>
0AAA-0AB0, 0AB2-0AB3, 0AB5-0AB9, 0ABD-0AC5,
- 0AC7-0AC9, 0ACB-0ACD, 0AD0, 0AE0</pre>
+ 0AC7-0AC9, 0ACB-0ACD, 0AD0, 0AE0
+</pre>
Oriya: 0B01-0B03, 0B05-0B0C, 0B0F-0B10, 0B13-0B28, 0B2A-0B30,
<!--page 453 -->
<pre>
0B32-0B33, 0B36-0B39, 0B3E-0B43, 0B47-0B48, 0B4B-0B4D,
Oriya: 0B01-0B03, 0B05-0B0C, 0B0F-0B10, 0B13-0B28, 0B2A-0B30,
<!--page 453 -->
<pre>
0B32-0B33, 0B36-0B39, 0B3E-0B43, 0B47-0B48, 0B4B-0B4D,
Tamil: 0B82-0B83, 0B85-0B8A, 0B8E-0B90, 0B92-0B95, 0B99-0B9A,
<pre>
0B9C, 0B9E-0B9F, 0BA3-0BA4, 0BA8-0BAA, 0BAE-0BB5,
Tamil: 0B82-0B83, 0B85-0B8A, 0B8E-0B90, 0B92-0B95, 0B99-0B9A,
<pre>
0B9C, 0B9E-0B9F, 0BA3-0BA4, 0BA8-0BAA, 0BAE-0BB5,
- 0BB7-0BB9, 0BBE-0BC2, 0BC6-0BC8, 0BCA-0BCD</pre>
+ 0BB7-0BB9, 0BBE-0BC2, 0BC6-0BC8, 0BCA-0BCD
+</pre>
Telugu: 0C01-0C03, 0C05-0C0C, 0C0E-0C10, 0C12-0C28, 0C2A-0C33,
<pre>
Telugu: 0C01-0C03, 0C05-0C0C, 0C0E-0C10, 0C12-0C28, 0C2A-0C33,
<pre>
- 0C35-0C39, 0C3E-0C44, 0C46-0C48, 0C4A-0C4D, 0C60-0C61</pre>
+ 0C35-0C39, 0C3E-0C44, 0C46-0C48, 0C4A-0C4D, 0C60-0C61
+</pre>
Kannada: 0C82-0C83, 0C85-0C8C, 0C8E-0C90, 0C92-0CA8, 0CAA-0CB3,
<pre>
0CB5-0CB9, 0CBE-0CC4, 0CC6-0CC8, 0CCA-0CCD, 0CDE,
Kannada: 0C82-0C83, 0C85-0C8C, 0C8E-0C90, 0C92-0CA8, 0CAA-0CB3,
<pre>
0CB5-0CB9, 0CBE-0CC4, 0CC6-0CC8, 0CCA-0CCD, 0CDE,
Malayalam: 0D02-0D03, 0D05-0D0C, 0D0E-0D10, 0D12-0D28, 0D2A-0D39,
<pre>
Malayalam: 0D02-0D03, 0D05-0D0C, 0D0E-0D10, 0D12-0D28, 0D2A-0D39,
<pre>
- 0D3E-0D43, 0D46-0D48, 0D4A-0D4D, 0D60-0D61</pre>
+ 0D3E-0D43, 0D46-0D48, 0D4A-0D4D, 0D60-0D61
+</pre>
Thai: 0E01-0E3A, 0E40-0E5B
Lao: 0E81-0E82, 0E84, 0E87-0E88, 0E8A, 0E8D, 0E94-0E97,
<pre>
0E99-0E9F, 0EA1-0EA3, 0EA5, 0EA7, 0EAA-0EAB,
0EAD-0EAE, 0EB0-0EB9, 0EBB-0EBD, 0EC0-0EC4, 0EC6,
Thai: 0E01-0E3A, 0E40-0E5B
Lao: 0E81-0E82, 0E84, 0E87-0E88, 0E8A, 0E8D, 0E94-0E97,
<pre>
0E99-0E9F, 0EA1-0EA3, 0EA5, 0EA7, 0EAA-0EAB,
0EAD-0EAE, 0EB0-0EB9, 0EBB-0EBD, 0EC0-0EC4, 0EC6,
Tibetan: 0F00, 0F18-0F19, 0F35, 0F37, 0F39, 0F3E-0F47, 0F49-0F69,
<pre>
0F71-0F84, 0F86-0F8B, 0F90-0F95, 0F97, 0F99-0FAD,
Tibetan: 0F00, 0F18-0F19, 0F35, 0F37, 0F39, 0F3E-0F47, 0F49-0F69,
<pre>
0F71-0F84, 0F86-0F8B, 0F90-0F95, 0F97, 0F99-0FAD,
Georgian: 10A0-10C5, 10D0-10F6
Hiragana: 3041-3093, 309B-309C
Katakana: 30A1-30F6, 30FB-30FC
Georgian: 10A0-10C5, 10D0-10F6
Hiragana: 3041-3093, 309B-309C
Katakana: 30A1-30F6, 30FB-30FC
Digits: 0660-0669, 06F0-06F9, 0966-096F, 09E6-09EF, 0A66-0A6F,
<pre>
0AE6-0AEF, 0B66-0B6F, 0BE7-0BEF, 0C66-0C6F, 0CE6-0CEF,
Digits: 0660-0669, 06F0-06F9, 0966-096F, 09E6-09EF, 0A66-0A6F,
<pre>
0AE6-0AEF, 0B66-0B6F, 0BE7-0BEF, 0C66-0C6F, 0CE6-0CEF,
- 0D66-0D6F, 0E50-0E59, 0ED0-0ED9, 0F20-0F33</pre>
+ 0D66-0D6F, 0E50-0E59, 0ED0-0ED9, 0F20-0F33
+</pre>
Special characters: 00B5, 00B7, 02B0-02B8, 02BB, 02BD-02C1, 02D0-02D1,
<!--page 454 -->
<pre>
02E0-02E4, 037A, 0559, 093D, 0B3D, 1FBE, 203F-2040, 2102,
2107, 210A-2113, 2115, 2118-211D, 2124, 2126, 2128, 212A-2131,
Special characters: 00B5, 00B7, 02B0-02B8, 02BB, 02BD-02C1, 02D0-02D1,
<!--page 454 -->
<pre>
02E0-02E4, 037A, 0559, 093D, 0B3D, 1FBE, 203F-2040, 2102,
2107, 210A-2113, 2115, 2118-211D, 2124, 2126, 2128, 212A-2131,
- 2133-2138, 2160-2182, 3005-3007, 3021-3029</pre>
+ 2133-2138, 2160-2182, 3005-3007, 3021-3029
+</pre>
The contents of the header <a href="#7.10"><limits.h></a> are given below, in alphabetical order. The
minimum magnitudes shown shall be replaced by implementation-defined magnitudes
with the same sign. The values shall all be constant expressions suitable for use in #if
preprocessing directives. The components are described further in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
The contents of the header <a href="#7.10"><limits.h></a> are given below, in alphabetical order. The
minimum magnitudes shown shall be replaced by implementation-defined magnitudes
with the same sign. The values shall all be constant expressions suitable for use in #if
preprocessing directives. The components are described further in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
The contents of the header <a href="#7.7"><float.h></a> are given below. All integer values, except
FLT_ROUNDS, shall be constant expressions suitable for use in #if preprocessing
directives; all floating values shall be constant expressions. The components are
The contents of the header <a href="#7.7"><float.h></a> are given below. All integer values, except
FLT_ROUNDS, shall be constant expressions suitable for use in #if preprocessing
directives; all floating values shall be constant expressions. The components are
The values given in the following list shall be replaced by implementation-defined
constant expressions that are greater or equal in magnitude (absolute value) to those
shown, with the same sign:
<!--page 455 -->
The values given in the following list shall be replaced by implementation-defined
constant expressions that are greater or equal in magnitude (absolute value) to those
shown, with the same sign:
<!--page 455 -->
The values given in the following list shall be replaced by implementation-defined
constant expressions with values that are greater than or equal to those shown:
The values given in the following list shall be replaced by implementation-defined
constant expressions with values that are greater than or equal to those shown:
The values given in the following list shall be replaced by implementation-defined
constant expressions with (positive) values that are less than or equal to those shown:
<!--page 456 -->
The values given in the following list shall be replaced by implementation-defined
constant expressions with (positive) values that are less than or equal to those shown:
<!--page 456 -->
</ul>
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.<sup><a href="#note308"><b>308)</b></a></sup>
</ul>
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.<sup><a href="#note308"><b>308)</b></a></sup>
<p><small><a name="note307" href="#note307">307)</a> ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit
and quadruple 128-bit IEC 60559 formats.
</small>
<p><small><a name="note307" href="#note307">307)</a> ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit
and quadruple 128-bit IEC 60559 formats.
</small>
the term NaN to denote quiet NaNs. The NAN and INFINITY macros and the nan
functions in <a href="#7.12"><math.h></a> provide designations for IEC 60559 NaNs and infinities.
the term NaN to denote quiet NaNs. The NAN and INFINITY macros and the nan
functions in <a href="#7.12"><math.h></a> provide designations for IEC 60559 NaNs and infinities.
<p><small><a name="note309" href="#note309">309)</a> Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are
sufficient for closure of the arithmetic.
</small>
<p><small><a name="note309" href="#note309">309)</a> Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are
sufficient for closure of the arithmetic.
</small>
integral part is within the range of the integer type raises the ''inexact'' floating-point
exception is unspecified.<sup><a href="#note310"><b>310)</b></a></sup>
integral part is within the range of the integer type raises the ''inexact'' floating-point
exception is unspecified.<sup><a href="#note310"><b>310)</b></a></sup>
<p><small><a name="note310" href="#note310">310)</a> 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
<p><small><a name="note310" href="#note310">310)</a> 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
<p><small><a name="note311" href="#note311">311)</a> 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
<p><small><a name="note311" href="#note311">311)</a> 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
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.
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.
<p><!--para 2 -->
A contracted expression should raise floating-point exceptions in a manner generally
consistent with the basic arithmetic operations. A contracted expression should deliver
<p><!--para 2 -->
A contracted expression should raise floating-point exceptions in a manner generally
consistent with the basic arithmetic operations. A contracted expression should deliver
IEC 60559 dynamic rounding precision and trap enablement modes, if the
implementation supports them.<sup><a href="#note312"><b>312)</b></a></sup>
IEC 60559 dynamic rounding precision and trap enablement modes, if the
implementation supports them.<sup><a href="#note312"><b>312)</b></a></sup>
<a href="#7.6"><fenv.h></a>) is ''on'', these changes to the floating-point state are treated as side effects
which respect sequence points.<sup><a href="#note313"><b>313)</b></a></sup>
<a href="#7.6"><fenv.h></a>) is ''on'', these changes to the floating-point state are treated as side effects
which respect sequence points.<sup><a href="#note313"><b>313)</b></a></sup>
<p><small><a name="note313" href="#note313">313)</a> 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 <a href="#F.8">F.8</a>).
<p><small><a name="note313" href="#note313">313)</a> 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 <a href="#F.8">F.8</a>).
<li> The rounding precision mode (if supported) is set so that results are not shortened.
<li> Trapping or stopping (if supported) is disabled on all floating-point exceptions.
</ul>
<li> The rounding precision mode (if supported) is set so that results are not shortened.
<li> Trapping or stopping (if supported) is disabled on all floating-point exceptions.
</ul>
floating-point exception, other than ''inexact'';<sup><a href="#note314"><b>314)</b></a></sup> the implementation should then
proceed with the translation of the program.
floating-point exception, other than ''inexact'';<sup><a href="#note314"><b>314)</b></a></sup> the implementation should then
proceed with the translation of the program.
<p><small><a name="note314" href="#note314">314)</a> 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
<p><small><a name="note314" href="#note314">314)</a> 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
For the static initialization, the division is done at translation time, raising no (execution-time) floating-
point exceptions. On the other hand, for the three automatic initializations the invalid division occurs at
For the static initialization, the division is done at translation time, raising no (execution-time) floating-
point exceptions. On the other hand, for the three automatic initializations the invalid division occurs at
<p><small><a name="note315" href="#note315">315)</a> Where the state for the FENV_ACCESS pragma is ''on'', results of inexact expressions like 1.0/3.0
are affected by rounding modes set at execution time, and expressions such as 0.0/0.0 and
1.0/0.0 generate execution-time floating-point exceptions. The programmer can achieve the
efficiency of translation-time evaluation through static initialization, such as
<pre>
<p><small><a name="note315" href="#note315">315)</a> Where the state for the FENV_ACCESS pragma is ''on'', results of inexact expressions like 1.0/3.0
are affected by rounding modes set at execution time, and expressions such as 0.0/0.0 and
1.0/0.0 generate execution-time floating-point exceptions. The programmer can achieve the
efficiency of translation-time evaluation through static initialization, such as
<pre>
The static initialization of v raises no (execution-time) floating-point exceptions because its computation is
done at translation time. The automatic initialization of u and w require an execution-time conversion to
float of the wider value 1.1e75, which raises floating-point exceptions. The automatic initializations
The static initialization of v raises no (execution-time) floating-point exceptions because its computation is
done at translation time. The automatic initialization of u and w require an execution-time conversion to
float of the wider value 1.1e75, which raises floating-point exceptions. The automatic initializations
<p><small><a name="note316" href="#note316">316)</a> Use of float_t and double_t variables increases the likelihood of translation-time computation.
For example, the automatic initialization
<pre>
<p><small><a name="note316" href="#note316">316)</a> Use of float_t and double_t variables increases the likelihood of translation-time computation.
For example, the automatic initialization
<pre>
x + 1 might raise floating-point exceptions, so cannot be removed. And since the loop
body might not execute (maybe 0 >= n), x + 1 cannot be moved out of the loop. (Of
course these optimizations are valid if the implementation can rule out the nettlesome
x + 1 might raise floating-point exceptions, so cannot be removed. And since the loop
body might not execute (maybe 0 >= n), x + 1 cannot be moved out of the loop. (Of
course these optimizations are valid if the implementation can rule out the nettlesome
constants generally do not yield numerically equivalent
expressions, if the constants are exact then such
transformations can be made on IEC 60559 machines
constants generally do not yield numerically equivalent
expressions, if the constants are exact then such
transformations can be made on IEC 60559 machines
x - y <-> -(y - x) The expressions x - y and -(y - x) are not
<pre>
equivalent because 1 - 1 is +0 but -(1 - 1) is -0 (in the
x - y <-> -(y - x) The expressions x - y and -(y - x) are not
<pre>
equivalent because 1 - 1 is +0 but -(1 - 1) is -0 (in the
x + 0->x The expressions x + 0 and x are not equivalent if x is
<pre>
-0, because (-0) + (+0) yields +0 (in the default
x + 0->x The expressions x + 0 and x are not equivalent if x is
<pre>
-0, because (-0) + (+0) yields +0 (in the default
x - 0->x (+0) - (+0) yields -0 when rounding is downward
<pre>
(toward -(inf)), but +0 otherwise, and (-0) - (+0) always
yields -0; so, if the state of the FENV_ACCESS pragma
is ''off'', promising default rounding, then the
x - 0->x (+0) - (+0) yields -0 when rounding is downward
<pre>
(toward -(inf)), but +0 otherwise, and (-0) - (+0) always
yields -0; so, if the state of the FENV_ACCESS pragma
is ''off'', promising default rounding, then the
-x <-> 0 - x The expressions -x and 0 - x are not equivalent if x
<pre>
is +0, because -(+0) yields -0, but 0 - (+0) yields +0
-x <-> 0 - x The expressions -x and 0 - x are not equivalent if x
<pre>
is +0, because -(+0) yields -0, but 0 - (+0) yields +0
<p><small><a name="note317" href="#note317">317)</a> Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
other transformations that remove arithmetic operators.
</small>
<p><small><a name="note317" href="#note317">317)</a> Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
other transformations that remove arithmetic operators.
</small>
which would be desirable if extra code were required to
cause the ''invalid'' floating-point exception for
unordered cases, could be performed provided the state
which would be desirable if extra code were required to
cause the ''invalid'' floating-point exception for
unordered cases, could be performed provided the state
The sense of relational operators shall be maintained. This includes handling unordered
cases as expressed by the source code.
<p><!--para 2 -->
The sense of relational operators shall be maintained. This includes handling unordered
cases as expressed by the source code.
<p><!--para 2 -->
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.
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.
<p><!--para 1 -->
This subclause contains specifications of <a href="#7.12"><math.h></a> facilities that are particularly suited
for IEC 60559 implementations.
<p><!--para 1 -->
This subclause contains specifications of <a href="#7.12"><math.h></a> facilities that are particularly suited
for IEC 60559 implementations.
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.
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.
<p><!--para 13 -->
If a function with one or more NaN arguments returns a NaN result, the result should be
the same as one of the NaN arguments (after possible type conversion), except perhaps
for the sign.
<p><!--para 13 -->
If a function with one or more NaN arguments returns a NaN result, the result should be
the same as one of the NaN arguments (after possible type conversion), except perhaps
for the sign.
<p><small><a name="note320" href="#note320">320)</a> IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on
when the floating-point exception is raised.
</small>
<p><small><a name="note320" href="#note320">320)</a> IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on
when the floating-point exception is raised.
</small>
<p><small><a name="note322" href="#note322">322)</a> atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise
the ''divide-by-zero'' floating-point exception.
</small>
<p><small><a name="note322" href="#note322">322)</a> atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise
the ''divide-by-zero'' floating-point exception.
</small>
{
*exp = (value == 0) ? 0 : (int)(1 + logb(value));
return scalbn(value, -(*exp));
{
*exp = (value == 0) ? 0 : (int)(1 + logb(value));
return scalbn(value, -(*exp));
The round functions may, but are not required to, raise the ''inexact'' floating-point
exception for non-integer numeric arguments, as this implementation does.
The round functions may, but are not required to, raise the ''inexact'' floating-point
exception for non-integer numeric arguments, as this implementation does.
result = remainder(fabs(x), (y = fabs(y)));
if (signbit(result)) result += y;
return copysign(result, x);
result = remainder(fabs(x), (y = fabs(y)));
if (signbit(result)) result += y;
return copysign(result, x);
The body of the fmax function might be<sup><a href="#note323"><b>323)</b></a></sup>
<pre>
{ return (isgreaterequal(x, y) ||
The body of the fmax function might be<sup><a href="#note323"><b>323)</b></a></sup>
<pre>
{ return (isgreaterequal(x, y) ||
<p><small><a name="note323" href="#note323">323)</a> 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.
</small>
<p><small><a name="note323" href="#note323">323)</a> 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.
</small>
<p><!--para 1 -->
If one operand has real type and the other operand has imaginary type, then the result has
imaginary type. If both operands have imaginary type, then the result has real type. (If
<p><!--para 1 -->
If one operand has real type and the other operand has imaginary type, then the result has
imaginary type. If both operands have imaginary type, then the result has real type. (If
If the operands are not both complex, then the result and floating-point exception
behavior of the * operator is defined by the usual mathematical formula:
<pre>
If the operands are not both complex, then the result and floating-point exception
behavior of the * operator is defined by the usual mathematical formula:
<pre>
If the second operand is not complex, then the result and floating-point exception
behavior of the / operator is defined by the usual mathematical formula:
<pre>
If the second operand is not complex, then the result and floating-point exception
behavior of the / operator is defined by the usual mathematical formula:
<pre>
The * and / operators satisfy the following infinity properties for all real, imaginary, and
complex operands:<sup><a href="#note325"><b>325)</b></a></sup>
<ul>
The * and / operators satisfy the following infinity properties for all real, imaginary, and
complex operands:<sup><a href="#note325"><b>325)</b></a></sup>
<ul>
EXAMPLE 1 Multiplication of double _Complex operands could be implemented as follows. Note
that the imaginary unit I has imaginary type (see <a href="#G.6">G.6</a>).
<!--page 483 -->
EXAMPLE 1 Multiplication of double _Complex operands could be implemented as follows. Note
that the imaginary unit I has imaginary type (see <a href="#G.6">G.6</a>).
<!--page 483 -->
This implementation achieves the required treatment of infinities at the cost of only one isnan test in
ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur.
<p><!--para 8 -->
EXAMPLE 2 Division of two double _Complex operands could be implemented as follows.
<!--page 484 -->
This implementation achieves the required treatment of infinities at the cost of only one isnan test in
ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur.
<p><!--para 8 -->
EXAMPLE 2 Division of two double _Complex operands could be implemented as follows.
<!--page 484 -->
Scaling the denominator alleviates the main overflow and underflow problem, which is more serious than
for multiplication. In the spirit of the multiplication example above, this code does not defend against
overflow and underflow in the calculation of the numerator. Scaling with the scalbn function, instead of
with division, provides better roundoff characteristics.
Scaling the denominator alleviates the main overflow and underflow problem, which is more serious than
for multiplication. In the spirit of the multiplication example above, this code does not defend against
overflow and underflow in the calculation of the numerator. Scaling with the scalbn function, instead of
with division, provides better roundoff characteristics.
<p><small><a name="note325" href="#note325">325)</a> 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'').
</small>
<h4><a name="G.5.2" href="#G.5.2">G.5.2 Additive operators</a></h4>
<p><small><a name="note325" href="#note325">325)</a> 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'').
</small>
<h4><a name="G.5.2" href="#G.5.2">G.5.2 Additive operators</a></h4>
<p><!--para 1 -->
If both operands have imaginary type, then the result has imaginary type. (If one operand
has real type and the other operand has imaginary type, or if either operand has complex
<p><!--para 1 -->
If both operands have imaginary type, then the result has imaginary type. (If one operand
has real type and the other operand has imaginary type, or if either operand has complex
In all cases the result and floating-point exception behavior of a + or - operator is defined
by the usual mathematical formula:
<pre>
In all cases the result and floating-point exception behavior of a + or - operator is defined
by the usual mathematical formula:
<pre>
are defined, respectively, as _Imaginary and a constant expression of type const
float _Imaginary with the value of the imaginary unit. The macro
<pre>
are defined, respectively, as _Imaginary and a constant expression of type const
float _Imaginary with the value of the imaginary unit. The macro
<pre>
is defined to be _Imaginary_I (not _Complex_I as stated in <a href="#7.3">7.3</a>). Notwithstanding
the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and then perhaps redefine the macro
imaginary.
is defined to be _Imaginary_I (not _Complex_I as stated in <a href="#7.3">7.3</a>). Notwithstanding
the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and then perhaps redefine the macro
imaginary.
<p><!--para 6 -->
Each of the functions cabs and carg is specified by a formula in terms of a real
function (whose special cases are covered in <a href="#F">annex F</a>):
<p><!--para 6 -->
Each of the functions cabs and carg is specified by a formula in terms of a real
function (whose special cases are covered in <a href="#F">annex F</a>):
Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by
a formula in terms of other complex functions (whose special cases are specified below):
Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by
a formula in terms of other complex functions (whose special cases are specified below):
For the other functions, the following subclauses specify behavior for special cases,
including treatment of the ''invalid'' and ''divide-by-zero'' floating-point exceptions. For
families of functions, the specifications apply to all of the functions even though only the
For the other functions, the following subclauses specify behavior for special cases,
including treatment of the ''invalid'' and ''divide-by-zero'' floating-point exceptions. For
families of functions, the specifications apply to all of the functions even though only the
The cpow functions raise floating-point exceptions if appropriate for the calculation of
the parts of the result, and may raise spurious exceptions.<sup><a href="#note327"><b>327)</b></a></sup>
The cpow functions raise floating-point exceptions if appropriate for the calculation of
the parts of the result, and may raise spurious exceptions.<sup><a href="#note327"><b>327)</b></a></sup>
<p><small><a name="note327" href="#note327">327)</a> This allows cpow( z , c ) to be implemented as cexp(c clog( z )) without precluding
implementations that treat special cases more carefully.
</small>
<p><small><a name="note327" href="#note327">327)</a> This allows cpow( z , c ) to be implemented as cexp(c clog( z )) without precluding
implementations that treat special cases more carefully.
</small>
<p><!--para 1 -->
Type-generic macros that accept complex arguments also accept imaginary arguments. If
an argument is imaginary, the macro expands to an expression whose type is real,
<p><!--para 1 -->
Type-generic macros that accept complex arguments also accept imaginary arguments. If
an argument is imaginary, the macro expands to an expression whose type is real,
The parameters for the integer data types can be accessed by the following:
maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX,
<pre>
The parameters for the integer data types can be accessed by the following:
maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX,
<pre>
minint INT_MIN, LONG_MIN, LLONG_MIN
<p><!--para 3 -->
The parameter ''bounded'' is always true, and is not provided. The parameter ''minint''
minint INT_MIN, LONG_MIN, LLONG_MIN
<p><!--para 3 -->
The parameter ''bounded'' is always true, and is not provided. The parameter ''minint''
exponentF 1.f+logbf(x), 1.0+logb(x), 1.L+logbl(x)
scaleF scalbnf(x, n), scalbn(x, n), scalbnl(x, n),
<pre>
exponentF 1.f+logbf(x), 1.0+logb(x), 1.L+logbl(x)
scaleF scalbnf(x, n), scalbn(x, n), scalbnl(x, n),
<pre>
- scalblnf(x, li), scalbln(x, li), scalblnl(x, li)</pre>
+ scalblnf(x, li), scalbln(x, li), scalblnl(x, li)
+</pre>
intpartF modff(x, &y), modf(x, &y), modfl(x, &y)
fractpartF modff(x, &y), modf(x, &y), modfl(x, &y)
eqF x == y
intpartF modff(x, &y), modf(x, &y), modfl(x, &y)
fractpartF modff(x, &y), modf(x, &y), modfl(x, &y)
eqF x == y
cvtI' -> I (int)i, (long int)i, (long long int)i,
<pre>
(unsigned int)i, (unsigned long int)i,
cvtI' -> I (int)i, (long int)i, (long long int)i,
<pre>
(unsigned int)i, (unsigned long int)i,
cvtF -> I (int)x, (long int)x, (long long int)x,
<pre>
(unsigned int)x, (unsigned long int)x,
cvtF -> I (int)x, (long int)x, (long long int)x,
<pre>
(unsigned int)x, (unsigned long int)x,
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
<p><!--para 2 -->
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
<p><!--para 2 -->
An implementation may generate warnings in many situations, none of which are
specified as part of this International Standard. The following are a few of the more
common situations.
An implementation may generate warnings in many situations, none of which are
specified as part of this International Standard. The following are a few of the more
common situations.
The asm keyword may be used to insert assembly language directly into the translator
output (<a href="#6.8">6.8</a>). The most common implementation is via a statement of the form:
<pre>
The asm keyword may be used to insert assembly language directly into the translator
output (<a href="#6.8">6.8</a>). The most common implementation is via a statement of the form:
<pre>