<!--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>
</ul>
</ul>
<li><a href="#A">Annex A (informative) Language syntax summary</a>
</ul>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<h3><a name="3.18" href="#3.18">3.18</a></h3>
<p><!--para 1 -->
-<b> ??? x???</b><br>
+<b> [^ x ^]</b><br>
ceiling of x: the least integer greater than or equal to x
<p><!--para 2 -->
- EXAMPLE ???2.4??? is 3, ???-2.4??? is -2.
+ EXAMPLE [^2.4^] is 3, [^-2.4^] is -2.
<h3><a name="3.19" href="#3.19">3.19</a></h3>
<p><!--para 1 -->
-<b> ??? x???</b><br>
+<b> [_ x _]</b><br>
floor of x: the greatest integer less than or equal to x
<p><!--para 2 -->
- EXAMPLE ???2.4??? is 2, ???-2.4??? is -3.
+ EXAMPLE [_2.4_] is 2, [_-2.4_] is -3.
<!--page 19 -->
<h2><a name="4" href="#4">4. Conformance</a></h2>
<!--page 21 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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:
/* ... */
fesetround(FE_UPWARD);
/* ... */
- #endif</pre>
+ #endif
+</pre>
</small>
<p><small><a name="note3" href="#note3">3)</a> This implies that a conforming implementation reserves no identifiers other than those explicitly
<!--page 23 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
EXAMPLE An implementation shall issue a diagnostic for the translation unit:
<pre>
char i;
- int i;</pre>
+ int i;
+</pre>
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
prototype for this function. It shall be defined with a return type of int and with no
parameters:
<pre>
- int main(void) { /* ... */ }</pre>
+ int main(void) { /* ... */ }
+</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>
- int main(int argc, char *argv[]) { /* ... */ }</pre>
+ int main(int argc, char *argv[]) { /* ... */ }
+</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
startup and program termination.
</ul>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<pre>
char c1, c2;
/* ... */
- c1 = c1 + c2;</pre>
+ c1 = c1 + c2;
+</pre>
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
float f1, f2;
double d;
/* ... */
- f1 = f2 * d;</pre>
+ f1 = f2 * d;
+</pre>
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).
double d1, d2;
float f;
d1 = f = expression;
- d2 = (float) expression;</pre>
+ d2 = (float) expression;
+</pre>
the values assigned to d1 and d2 are required to have been converted to float.
<p><!--para 13 -->
x = (x * y) * z; // not equivalent to x *= y * z;
z = (x - y) + y ; // not equivalent to z = x;
z = x + x * y; // not equivalent to z = x * (1.0 + y);
- y = x / 5.0; // not equivalent to y = x * 0.2;</pre>
+ y = x / 5.0; // not equivalent to y = x * 0.2;
+</pre>
<p><!--para 14 -->
EXAMPLE 6 To illustrate the grouping behavior of expressions, in the following fragment
<pre>
int a, b;
/* ... */
- a = a + 32760 + b + 5;</pre>
+ a = a + 32760 + b + 5;
+</pre>
the expression statement behaves exactly the same as
<pre>
- a = (((a + 32760) + b) + 5);</pre>
+ a = (((a + 32760) + b) + 5);
+</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>
- a = ((a + b) + 32765);</pre>
+ a = ((a + b) + 32765);
+</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>
- a = ((a + 32765) + b);</pre>
+ a = ((a + 32765) + b);
+</pre>
or
<pre>
- a = (a + (b + 32765));</pre>
+ a = (a + (b + 32765));
+</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
int sum;
char *p;
/* ... */
- sum = sum * 10 - '0' + (*p++ = getchar());</pre>
+ sum = sum * 10 - '0' + (*p++ = getchar());
+</pre>
the expression statement is grouped as if it were written as
<pre>
- sum = (((sum * 10) - '0') + ((*(p++)) = (getchar())));</pre>
+ sum = (((sum * 10) - '0') + ((*(p++)) = (getchar())));
+</pre>
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.
signal function (<a href="#7.14">7.14</a>), files (<a href="#7.19.3">7.19.3</a>).
<!--page 29 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
members: the 26 uppercase letters of the Latin alphabet
<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</pre>
+ N O P Q R S T U V W X Y Z
+</pre>
the 26 lowercase letters of the Latin alphabet
<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</pre>
+ n o p q r s t u v w x y z
+</pre>
the 10 decimal digits
<pre>
- 0 1 2 3 4 5 6 7 8 9</pre>
+ 0 1 2 3 4 5 6 7 8 9
+</pre>
the following 29 graphic characters
<pre>
! " # % & ' ( ) * + , - . / :
- ; < = > ? [ \ ] ^ _ { | } ~</pre>
+ ; < = > ? [ \ ] ^ _ { | } ~
+</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
<pre>
??= # ??) ] ??! |
??( [ ??' ^ ??> }
- ??/ \ ??< { ??- ~</pre>
+ ??/ \ ??< { ??- ~
+</pre>
No other trigraph sequences exist. Each ? that does not begin one of the trigraphs listed
above is not changed.
<p><!--para 2 -->
EXAMPLE 1
<pre>
- ??=define arraycheck(a, b) a??(b??) ??!??! b??(a??)</pre>
+ ??=define arraycheck(a, b) a??(b??) ??!??! b??(a??)
+</pre>
becomes
<pre>
- #define arraycheck(a, b) a[b] || b[a]</pre>
+ #define arraycheck(a, b) a[b] || b[a]
+</pre>
<p><!--para 3 -->
EXAMPLE 2 The following source line
<pre>
- printf("Eh???/n");</pre>
+ printf("Eh???/n");
+</pre>
becomes (after replacement of the trigraph sequence ??/)
<pre>
- printf("Eh?\n");</pre>
+ printf("Eh?\n");
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<li> 63 levels of nested structure or union definitions in a single struct-declaration-list
</ul>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>).
-<h5><a name="5.2.4.2.1" href="#5.2.4.2.1">5.2.4.2.1 Sizes of integer types <limits.h></a></h5>
+<h5><a name="5.2.4.2.1" href="#5.2.4.2.1">5.2.4.2.1 Sizes of integer types <limits.h></a></h5>
<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)
-<pre> CHAR_BIT 8</pre>
+<pre>
+ CHAR_BIT 8
+</pre>
<li> minimum value for an object of type signed char
-<pre> SCHAR_MIN -127 // -(2<sup>7</sup> - 1)</pre>
+<pre>
+ SCHAR_MIN -127 // -(2<sup>7</sup> - 1)
+</pre>
<li> maximum value for an object of type signed char
-<pre> SCHAR_MAX +127 // 2<sup>7</sup> - 1</pre>
+<pre>
+ SCHAR_MAX +127 // 2<sup>7</sup> - 1
+</pre>
<li> maximum value for an object of type unsigned char
-<pre> UCHAR_MAX 255 // 2<sup>8</sup> - 1</pre>
+<pre>
+ UCHAR_MAX 255 // 2<sup>8</sup> - 1
+</pre>
<li> minimum value for an object of type char
-<pre> CHAR_MIN see below</pre>
+<pre>
+ CHAR_MIN see below
+</pre>
<li> maximum value for an object of type char
-<pre> CHAR_MAX see below</pre>
+<pre>
+ CHAR_MAX see below
+</pre>
<li> maximum number of bytes in a multibyte character, for any supported locale
-<pre> MB_LEN_MAX 1</pre>
+<pre>
+ MB_LEN_MAX 1
+</pre>
<li> minimum value for an object of type short int
-<pre> SHRT_MIN -32767 // -(2<sup>15</sup> - 1)</pre>
+<pre>
+ SHRT_MIN -32767 // -(2<sup>15</sup> - 1)
+</pre>
<li> maximum value for an object of type short int
-<pre> SHRT_MAX +32767 // 2<sup>15</sup> - 1</pre>
+<pre>
+ SHRT_MAX +32767 // 2<sup>15</sup> - 1
+</pre>
<li> maximum value for an object of type unsigned short int
-<pre> USHRT_MAX 65535 // 2<sup>16</sup> - 1</pre>
+<pre>
+ USHRT_MAX 65535 // 2<sup>16</sup> - 1
+</pre>
<li> minimum value for an object of type int
-<pre> INT_MIN -32767 // -(2<sup>15</sup> - 1)</pre>
+<pre>
+ INT_MIN -32767 // -(2<sup>15</sup> - 1)
+</pre>
<li> maximum value for an object of type int
-<pre> INT_MAX +32767 // 2<sup>15</sup> - 1</pre>
+<pre>
+ INT_MAX +32767 // 2<sup>15</sup> - 1
+</pre>
<li> maximum value for an object of type unsigned int
-<pre> UINT_MAX 65535 // 2<sup>16</sup> - 1</pre>
+<pre>
+ UINT_MAX 65535 // 2<sup>16</sup> - 1
+</pre>
<li> minimum value for an object of type long int
-<pre> LONG_MIN -2147483647 // -(2<sup>31</sup> - 1)</pre>
+<pre>
+ LONG_MIN -2147483647 // -(2<sup>31</sup> - 1)
+</pre>
<li> maximum value for an object of type long int
-<pre> LONG_MAX +2147483647 // 2<sup>31</sup> - 1</pre>
+<pre>
+ LONG_MAX +2147483647 // 2<sup>31</sup> - 1
+</pre>
<li> maximum value for an object of type unsigned long int
-<pre> ULONG_MAX 4294967295 // 2<sup>32</sup> - 1</pre>
+<pre>
+ ULONG_MAX 4294967295 // 2<sup>32</sup> - 1
+</pre>
<!--page 35 -->
<li> minimum value for an object of type long long int
-<pre> LLONG_MIN -9223372036854775807 // -(2<sup>63</sup> - 1)</pre>
+<pre>
+ LLONG_MIN -9223372036854775807 // -(2<sup>63</sup> - 1)
+</pre>
<li> maximum value for an object of type long long int
-<pre> LLONG_MAX +9223372036854775807 // 2<sup>63</sup> - 1</pre>
+<pre>
+ LLONG_MAX +9223372036854775807 // 2<sup>63</sup> - 1
+</pre>
<li> maximum value for an object of type unsigned long long int
-<pre> ULLONG_MAX 18446744073709551615 // 2<sup>64</sup> - 1</pre>
+<pre>
+ ULLONG_MAX 18446744073709551615 // 2<sup>64</sup> - 1
+</pre>
</ul>
<p><!--para 2 -->
If the value of an object of type char is treated as a signed integer when used in an
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note15" href="#note15">15)</a> See <a href="#6.2.5">6.2.5</a>.
</small>
-<h5><a name="5.2.4.2.2" href="#5.2.4.2.2">5.2.4.2.2 Characteristics of floating types <float.h></a></h5>
+<h5><a name="5.2.4.2.2" href="#5.2.4.2.2">5.2.4.2.2 Characteristics of floating types <float.h></a></h5>
<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 2 -->
<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)
- fk nonnegative integers less than b (the significand digits)</pre>
+ f<sub>k</sub> nonnegative integers less than b (the significand digits)
+</pre>
+<p><!--para 2 -->
A floating-point number (x) is defined by the following model:
<pre>
p
- x = sb e (Sum) f k b-k ,
+ x = s b<sup>e</sup> (Sum) f<sub>k</sub> b<sup>-k</sup> , emin <= e <= emax
k=1
- emin <= e <= emax</pre>
+</pre>
<p><!--para 3 -->
- In addition to normalized floating-point numbers ( f 1 > 0 if x != 0), floating types may be
+ In addition to normalized floating-point numbers ( f<sub>1</sub> > 0 if x != 0), floating types may be
able to contain other kinds of floating-point numbers, such as subnormal floating-point
- numbers (x != 0, e = emin , f 1 = 0) and unnormalized floating-point numbers (x != 0,
- e > emin , f 1 = 0), and values that are not floating-point numbers, such as infinities and
+ numbers (x != 0, e = emin , f<sub>1</sub> = 0) and unnormalized floating-point numbers (x != 0,
+ e > emin , f<sub>1</sub> = 0), and values that are not floating-point numbers, such as infinities and
NaNs. A NaN is an encoding signifying Not-a-Number. A quiet NaN propagates
through almost every arithmetic operation without raising a floating-point exception; a
signaling NaN generally raises a floating-point exception when occurring as an
All integer values in the <a href="#7.7"><float.h></a> header, except FLT_ROUNDS, shall be constant
expressions suitable for use in #if preprocessing directives; all floating values shall be
constant expressions. All except DECIMAL_DIG, FLT_EVAL_METHOD, FLT_RADIX,
- and FLT_ROUNDS have separate names for all three floating-point types. The floating-
- point model representation is provided for all values except FLT_EVAL_METHOD and
+ and FLT_ROUNDS have separate names for all three floating-point types. The floating-point
+ model representation is provided for all values except FLT_EVAL_METHOD and
FLT_ROUNDS.
<p><!--para 7 -->
The rounding mode for floating-point addition is characterized by the implementation-
0 toward zero
1 to nearest
2 toward positive infinity
- 3 toward negative infinity</pre>
+ 3 toward negative infinity
+</pre>
All other values for FLT_ROUNDS characterize implementation-defined rounding
behavior.
<p><!--para 8 -->
operations and constants to the range and precision of the long double
type;
2 evaluate all operations and constants to the range and precision of the
- long double type.</pre>
+ long double type.
+</pre>
All other negative values for FLT_EVAL_METHOD characterize implementation-defined
behavior.
<p><!--para 9 -->
those shown, with the same sign:
<ul>
<li> radix of exponent representation, b
+<pre>
FLT_RADIX 2
+</pre>
<li> number of base-FLT_RADIX digits in the floating-point significand, p
+<pre>
FLT_MANT_DIG
DBL_MANT_DIG
LDBL_MANT_DIG
+</pre>
<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
- ???
- ??? ???1 + pmax log10 b??? otherwise</pre>
+ { pmax log10 b if b is a power of 10
+ {
+ { [^1 + pmax log10 b^] otherwise
+</pre>
+<pre>
DECIMAL_DIG 10
+</pre>
<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,
<!--page 38 -->
<pre>
- ??? p log10 b if b is a power of 10
- ???
- ??? ???( p - 1) log10 b??? otherwise</pre>
+ { p log10 b if b is a power of 10
+ {
+ { [_( p - 1) log10 b_] otherwise
+</pre>
+<pre>
FLT_DIG 6
DBL_DIG 10
LDBL_DIG 10
+</pre>
<li> minimum negative integer such that FLT_RADIX raised to one less than that power is
a normalized floating-point number, emin
+<pre>
FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
+</pre>
<li> minimum negative integer such that 10 raised to that power is in the range of
- normalized floating-point numbers, ???log10 b emin -1 ???
+ normalized floating-point numbers, [^log10 b<sup>emin -1</sup>^]
<pre>
- ??? ???</pre>
FLT_MIN_10_EXP -37
DBL_MIN_10_EXP -37
LDBL_MIN_10_EXP -37
+</pre>
<li> maximum integer such that FLT_RADIX raised to one less than that power is a
representable finite floating-point number, emax
+<pre>
FLT_MAX_EXP
DBL_MAX_EXP
LDBL_MAX_EXP
+</pre>
<li> maximum integer such that 10 raised to that power is in the range of representable
- finite floating-point numbers, ???log10 ((1 - b- p )b emax )???
+ finite floating-point numbers, [_log10 ((1 - b<sup>-p</sup>)b<sup>emax</sup>)_]
+<pre>
FLT_MAX_10_EXP +37
DBL_MAX_10_EXP +37
LDBL_MAX_10_EXP +37
+</pre>
</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- p )b emax
+<li> maximum representable finite floating-point number, (1 - b<sup>-p</sup>)b<sup>emax</sup>
+<pre>
FLT_MAX 1E+37
DBL_MAX 1E+37
LDBL_MAX 1E+37
+</pre>
</ul>
<p><!--para 11 -->
The values given in the following list shall be replaced by constant expressions with
implementation-defined (positive) values that are less than or equal to those shown:
<ul>
<li> the difference between 1 and the least value greater than 1 that is representable in the
- given floating point type, b1- p
+ given floating point type, b<sup>1-p</sup>
<!--page 39 -->
+<pre>
FLT_EPSILON 1E-5
DBL_EPSILON 1E-9
LDBL_EPSILON 1E-9
-<li> minimum normalized positive floating-point number, b emin -1
+</pre>
+<li> minimum normalized positive floating-point number, b<sup>emin -1</sup>
+<pre>
FLT_MIN 1E-37
DBL_MIN 1E-37
LDBL_MIN 1E-37
+</pre>
</ul>
- Recommended practice
+<p><b>Recommended practice</b>
<p><!--para 12 -->
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back
should be the identity function.
float:
<pre>
6
- x = s16e (Sum) f k 16-k ,
+ x = s 16<sup>e</sup> (Sum) f<sub>k</sub> 16<sup>-k</sup> , -31 <= e <= +32
k=1
- -31 <= e <= +32</pre>
+</pre>
<pre>
FLT_RADIX 16
FLT_MIN_10_EXP -38
FLT_MAX_EXP +32
FLT_MAX 3.40282347E+38F
- FLT_MAX_10_EXP +38</pre>
+ FLT_MAX_10_EXP +38
+</pre>
<p><!--para 14 -->
EXAMPLE 2 The following describes floating-point representations that also meet the requirements for
<a href="#7.7"><float.h></a> header for types float and double:
<pre>
24
- x f = s2e (Sum) f k 2-k ,
+ xf = s 2<sup>e</sup> (Sum) f<sub>k</sub> 2<sup>-k</sup> , -125 <= e <= +128
k=1
- -125 <= e <= +128</pre>
+</pre>
<pre>
53
- x d = s2e (Sum) f k 2-k ,
+ xd = s 2<sup>e</sup> (Sum) f<sub>k</sub> 2<sup>-k</sup> , -1021 <= e <= +1024
k=1
- -1021 <= e <= +1024</pre>
+</pre>
+
<pre>
FLT_RADIX 2
DECIMAL_DIG 17
FLT_MANT_DIG 24
FLT_EPSILON 1.19209290E-07F // decimal constant
- FLT_EPSILON 0X1P-23F // hex constant</pre>
+ FLT_EPSILON 0X1P-23F // hex constant
+</pre>
<!--page 40 -->
DBL_MAX_EXP +1024
DBL_MAX 1.7976931348623157E+308 // decimal constant
DBL_MAX 0X1.fffffffffffffP1023 // hex constant
- DBL_MAX_10_EXP +308</pre>
+ DBL_MAX_10_EXP +308
+</pre>
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 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
- { expressionopt }</pre>
+ { expression<sub>opt</sub> }
+</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
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
<!--page 44 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note24" href="#note24">24)</a> There is only one name space for tags even though three are possible.
</small>
<!--page 45 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
- pointer to a character type.39) Similarly, pointers to qualified or unqualified versions of
+ pointer to a character type.<sup><a href="#note39"><b>39)</b></a></sup> Similarly, pointers to qualified or unqualified versions of
compatible types shall have the same representation and alignment requirements. All
<p><b> Forward references</b>: compatible type and composite type (<a href="#6.2.7">6.2.7</a>), declarations (<a href="#6.7">6.7</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
Dictionary for Information Processing Systems.) A byte contains CHAR_BIT bits, and the values of
- type unsigned char range from 0 to 2
-
-<pre>
- CHAR_BIT
- - 1.</pre>
+ type unsigned char range from 0 to 2<sup>CHAR_BIT</sup>- 1.
</small>
<p><small><a name="note41" href="#note41">41)</a> Thus, an automatic variable can be initialized to a trap representation without causing undefined
behavior, but the value of the variable cannot be used until a proper value is stored in it.
For unsigned integer types other than unsigned char, the bits of the object
representation shall be divided into two groups: value bits and padding bits (there need
not be any of the latter). If there are N value bits, each bit shall represent a different
- power of 2 between 1 and 2 N -1 , so that objects of that type shall be capable of
- representing values from 0 to 2 N - 1 using a pure binary representation; this shall be
+ power of 2 between 1 and 2<sup>N-1</sup> , so that objects of that type shall be capable of
+ representing values from 0 to 2<sup>N</sup> - 1 using a pure binary representation; this shall be
known as the value representation. The values of any padding bits are unspecified.<sup><a href="#note44"><b>44)</b></a></sup>
<p><!--para 2 -->
For signed integer types, the bits of the object representation shall be divided into three
modified in one of the following ways:
<ul>
<li> the corresponding value with sign bit 0 is negated (sign and magnitude);
-<li> the sign bit has the value -(2 N ) (two's complement);
-<li> the sign bit has the value -(2 N - 1) (ones' complement ).
+<li> the sign bit has the value -(2<sup>N</sup> ) (two's complement);
+<li> the sign bit has the value -(2<sup>N</sup> - 1) (ones' complement ).
</ul>
Which of these applies is implementation-defined, as is whether the value with sign bit 1
and all value bits zero (for the first two), or with sign bit and all value bits 1 (for ones'
<!--page 52 -->
for signed integer types the width is one greater than the precision.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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]);
- int f(int (*)(char *), double (*)[]);</pre>
+ int f(int (*)(char *), double (*)[]);
+</pre>
The resulting composite type for the function is:
<!--page 54 -->
<pre>
- int f(int (*)(char *), double (*)[3]);</pre>
+ int f(int (*)(char *), double (*)[3]);
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note49" href="#note49">49)</a> The rules describe arithmetic on the mathematical value, not the value of a given type of expression.
</small>
in an implementation-defined manner. If the value being converted is outside the range of
values that can be represented, the behavior is undefined.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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 -->
-<p><!--para 2 -->
-<pre>
- First, if the corresponding real type of either operand is long double, the other
+<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
corresponding real type is long double.
- Otherwise, if the corresponding real type of either operand is double, the other
+<li> Otherwise, if the corresponding real type of either operand is double, the other
operand is converted, without change of type domain, to a type whose
corresponding real type is double.
- Otherwise, if the corresponding real type of either operand is float, the other
+<li> Otherwise, if the corresponding real type of either operand is float, the other
operand is converted, without change of type domain, to a type whose
corresponding real type is float.<sup><a href="#note51"><b>51)</b></a></sup>
- Otherwise, the integer promotions are performed on both operands. Then the
+<li> Otherwise, the integer promotions are performed on both operands. Then the
following rules are applied to the promoted operands:
- If both operands have the same type, then no further conversion is needed.
- Otherwise, if both operands have signed integer types or both have unsigned
+<ul>
+<li> If both operands have the same type, then no further conversion is needed.
+<li> Otherwise, if both operands have signed integer types or both have unsigned
integer types, the operand with the type of lesser integer conversion rank is
converted to the type of the operand with greater rank.
- Otherwise, if the operand that has unsigned integer type has rank greater or
+<li> Otherwise, if the operand that has unsigned integer type has rank greater or
equal to the rank of the type of the other operand, then the operand with
signed integer type is converted to the type of the operand with unsigned
integer type.
- Otherwise, if the type of the operand with signed integer type can represent
+<li> Otherwise, if the type of the operand with signed integer type can represent
all of the values of the type of the operand with unsigned integer type, then
the operand with unsigned integer type is converted to the type of the
operand with signed integer type.
- Otherwise, both operands are converted to the unsigned integer type
- corresponding to the type of the operand with signed integer type.</pre>
+<li> Otherwise, both operands are converted to the unsigned integer type
+ corresponding to the type of the operand with signed integer type.
+</ul>
+</ul>
+<p><!--para 2 -->
The values of floating operands and of the results of floating expressions may be
represented in greater precision and range than that required by the type; the types are not
changed thereby.<sup><a href="#note52"><b>52)</b></a></sup>
<!--page 58 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<!--page 59 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
capable of holding object pointers (<a href="#7.18.1.4">7.18.1.4</a>), simple assignment (<a href="#6.5.16.1">6.5.16.1</a>).
<!--page 61 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h3><a name="6.4" href="#6.4">6.4 Lexical elements</a></h3>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
token:
character-constant
string-literal
punctuator
- each non-white-space character that cannot be one of the above</pre>
-<h6>Constraints</h6>
+ each non-white-space character that cannot be one of the above
+</pre>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
keyword: one of
default inline struct _Imaginary
do int switch
double long typedef
- else register union</pre>
-<h6>Semantics</h6>
+ else register union
+</pre>
+<p><b>Semantics</b>
<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
<!--page 63 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
identifier:
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z
digit: one of
- 0 1 2 3 4 5 6 7 8 9</pre>
-<h6>Semantics</h6>
+ 0 1 2 3 4 5 6 7 8 9
+</pre>
+<p><b>Semantics</b>
<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
<!--page 64 -->
- Implementation limits
+<p><b>Implementation limits</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
</small>
<h5><a name="6.4.2.2" href="#6.4.2.2">6.4.2.2 Predefined identifiers</a></h5>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
- static const char __func__[] = "function-name";</pre>
+ static const char __func__[] = "function-name";
+</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
{
printf("%s\n", __func__);
/* ... */
- }</pre>
+ }
+</pre>
Each time the function is called, it will print to the standard output stream:
<pre>
- myfunc</pre>
+ myfunc
+</pre>
<p><b> Forward references</b>: function definitions (<a href="#6.9.1">6.9.1</a>).
<!--page 65 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
universal-character-name:
\U hex-quad hex-quad
hex-quad:
hexadecimal-digit hexadecimal-digit
- hexadecimal-digit hexadecimal-digit</pre>
-<h6>Constraints</h6>
+ hexadecimal-digit hexadecimal-digit
+</pre>
+<p><b>Constraints</b>
<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>
-<h6>Description</h6>
+<p><b>Description</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 66 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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).
</small>
<h4><a name="6.4.4" href="#6.4.4">6.4.4 Constants</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
constant:
integer-constant
floating-constant
enumeration-constant
- character-constant</pre>
-<h6>Constraints</h6>
+ character-constant
+</pre>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<!--page 67 -->
<pre>
integer-constant:
- decimal-constant integer-suffixopt
- octal-constant integer-suffixopt
- hexadecimal-constant integer-suffixopt
+ decimal-constant integer-suffix<sub>opt</sub>
+ octal-constant integer-suffix<sub>opt</sub>
+ hexadecimal-constant integer-suffix<sub>opt</sub>
decimal-constant:
nonzero-digit
decimal-constant digit
a b c d e f
A B C D E F
integer-suffix:
- unsigned-suffix long-suffixopt
+ unsigned-suffix long-suffix<sub>opt</sub>
unsigned-suffix long-long-suffix
- long-suffix unsigned-suffixopt
- long-long-suffix unsigned-suffixopt
+ long-suffix unsigned-suffix<sub>opt</sub>
+ long-long-suffix unsigned-suffix<sub>opt</sub>
unsigned-suffix: one of
u U
long-suffix: one of
l L
long-long-suffix: one of
- ll LL</pre>
-<h6>Description</h6>
+ ll LL
+</pre>
+<p><b>Description</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
The type of an integer constant is the first of the corresponding list in which its value can
be represented.
<!--page 68 -->
-<pre>
- Octal or Hexadecimal</pre>
- Suffix Decimal Constant Constant
-
- none int int
-<pre>
- long int unsigned int
- long long int long int
- unsigned long int
- long long int
- unsigned long long int</pre>
-
- u or U unsigned int unsigned int
-<pre>
- unsigned long int unsigned long int
- unsigned long long int unsigned long long int</pre>
-
- l or L long int long int
-<pre>
- long long int unsigned long int
- long long int
- unsigned long long int</pre>
-
- Both u or U unsigned long int unsigned long int
- and l or L unsigned long long int unsigned long long int
-
- ll or LL long long int long long int
-<pre>
- unsigned long long int</pre>
-
- Both u or U unsigned long long int unsigned long long int
- and ll or LL
+<table border=1>
+<tr><th> Suffix <th>Decimal Constant <th>Octal or Hexadecimal Constant
+<tr><td> none
+<td><pre>
+int
+long int
+long long int
+</pre>
+<td><pre>
+int
+unsigned int
+long int
+unsigned long int
+long long int
+unsigned long long int
+</pre>
+<tr><td> u or U
+<td><pre>
+unsigned int
+unsigned long int
+unsigned long long int
+</pre>
+<td><pre>
+unsigned int
+unsigned long int
+unsigned long long int
+</pre>
+<tr><td> l or L
+<td><pre>
+long int
+long long int
+</pre>
+<td><pre>
+long int
+unsigned long int
+long long int
+unsigned long long int
+</pre>
+<tr><td> Both u or U and l or L
+<td><pre>
+unsigned long int
+unsigned long long int
+</pre>
+<td><pre>
+unsigned long int
+unsigned long long int
+</pre>
+<tr><td> ll or LL
+<td><pre>
+long long int
+</pre>
+<td><pre>
+long long int
+unsigned long long int
+</pre>
+<tr><td> Both u or U and ll or LL
+<td><pre>
+unsigned long long int
+</pre>
+<td><pre>
+unsigned long long int
+</pre>
+</table>
<p><!--para 6 -->
If an integer constant cannot be represented by any type in its list, it may have an
extended integer type, if the extended integer type can represent its value. If all of the
<!--page 69 -->
<h5><a name="6.4.4.2" href="#6.4.4.2">6.4.4.2 Floating constants</a></h5>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<!--page 70 -->
<pre>
decimal-floating-constant
hexadecimal-floating-constant
decimal-floating-constant:
- fractional-constant exponent-partopt floating-suffixopt
- digit-sequence exponent-part floating-suffixopt
+ fractional-constant exponent-part<sub>opt</sub> floating-suffix<sub>opt</sub>
+ digit-sequence exponent-part floating-suffix<sub>opt</sub>
hexadecimal-floating-constant:
hexadecimal-prefix hexadecimal-fractional-constant
- binary-exponent-part floating-suffixopt
+ binary-exponent-part floating-suffix<sub>opt</sub>
hexadecimal-prefix hexadecimal-digit-sequence
- binary-exponent-part floating-suffixopt
+ binary-exponent-part floating-suffix<sub>opt</sub>
fractional-constant:
- digit-sequenceopt . digit-sequence
+ digit-sequence<sub>opt</sub> . digit-sequence
digit-sequence .
exponent-part:
- e signopt digit-sequence
- E signopt digit-sequence
+ e sign<sub>opt</sub> digit-sequence
+ E sign<sub>opt</sub> digit-sequence
sign: one of
+ -
digit-sequence:
digit
digit-sequence digit
hexadecimal-fractional-constant:
- hexadecimal-digit-sequenceopt .
+ hexadecimal-digit-sequence<sub>opt</sub> .
hexadecimal-digit-sequence
hexadecimal-digit-sequence .
binary-exponent-part:
- p signopt digit-sequence
- P signopt digit-sequence
+ p sign<sub>opt</sub> digit-sequence
+ P sign<sub>opt</sub> digit-sequence
hexadecimal-digit-sequence:
hexadecimal-digit
hexadecimal-digit-sequence hexadecimal-digit
floating-suffix: one of
- f l F L</pre>
-<h6>Description</h6>
+ f l F L
+</pre>
+<p><b>Description</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
- Recommended practice
+<p><b>Recommended practice</b>
<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
<!--page 71 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
enumeration-constant:
- identifier</pre>
-<h6>Semantics</h6>
+ identifier
+</pre>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<!--page 72 -->
<pre>
\ octal-digit octal-digit octal-digit
hexadecimal-escape-sequence:
\x hexadecimal-digit
- hexadecimal-escape-sequence hexadecimal-digit</pre>
-<h6>Description</h6>
+ hexadecimal-escape-sequence hexadecimal-digit
+</pre>
+<p><b>Description</b>
<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:
-<p><!--para 4 -->
<pre>
single quote ' \'
double quote " \"
question mark ? \?
backslash \ \\
octal character \octal digits
- hexadecimal character \x hexadecimal digits</pre>
+ hexadecimal character \x hexadecimal digits
+</pre>
+<p><!--para 4 -->
The double-quote " and question-mark ? are representable either by themselves or by the
escape sequences \" and \?, respectively, but the single-quote ' and the backslash \
shall be represented, respectively, by the escape sequences \' and \\.
<!--page 73 -->
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
(<a href="#7.20.7.2">7.20.7.2</a>).
<!--page 74 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
string-literal:
- " s-char-sequenceopt "
- L" s-char-sequenceopt "
+ " s-char-sequence<sub>opt</sub> "
+ L" s-char-sequence<sub>opt</sub> "
s-char-sequence:
s-char
s-char-sequence s-char
s-char:
any member of the source character set except
the double-quote ", backslash \, or new-line character
- escape-sequence</pre>
-<h6>Description</h6>
+ escape-sequence
+</pre>
+<p><b>Description</b>
<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
\".
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 7 -->
EXAMPLE This pair of adjacent character string literals
<pre>
- "\x12" "3"</pre>
+ "\x12" "3"
+</pre>
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
punctuator: one of
? : ; ...
= *= /= %= += -= <<= >>= &= ^= |=
, # ##
- <: :> <% %> %: %:%:</pre>
-<h6>Semantics</h6>
+ <: :> <% %> %: %:%:
+</pre>
+<p><b>Semantics</b>
<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 3 -->
In all aspects of the language, the six tokens<sup><a href="#note67"><b>67)</b></a></sup>
<pre>
- <: :> <% %> %: %:%:</pre>
+ <: :> <% %> %: %:%:
+</pre>
behave, respectively, the same as the six tokens
<pre>
- [ ] { } # ##</pre>
+ [ ] { } # ##
+</pre>
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.4.7" href="#6.4.7">6.4.7 Header names</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
header-name:
q-char-sequence q-char
q-char:
any member of the source character set except
- the new-line character and "</pre>
-<h6>Semantics</h6>
+ the new-line character and "
+</pre>
+<p><b>Semantics</b>
<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>.
<pre>
0x3<1/a.h>1e2
#include <1/a.h>
- #define const.member@$</pre>
+ #define const.member@$
+</pre>
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>}
- {#}{define} {const}{.}{member}{@}{$}</pre>
+ {#}{define} {const}{.}{member}{@}{$}
+</pre>
<p><b> Forward references</b>: source file inclusion (<a href="#6.10.2">6.10.2</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
pp-number:
pp-number E sign
pp-number p sign
pp-number P sign
- pp-number .</pre>
-<h6>Description</h6>
+ pp-number .
+</pre>
+<p><b>Description</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
- + p; // equivalent to m = n + p;</pre>
+ + p; // equivalent to m = n + p;
+</pre>
<!--page 79 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note71" href="#note71">71)</a> Thus, /* ... */ comments do not nest.
</small>
<!--page 81 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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;
a[i++] = i;
+</pre>
while allowing
+<pre>
i = i + 1;
- a[i] = i;</pre>
+ a[i] = i;
+</pre>
</small>
<p><small><a name="note74" href="#note74">74)</a> The syntax specifies the precedence of operators in the evaluation of an expression, which is the same
parentheses () (<a href="#6.5.1">6.5.1</a>), subscripting brackets [] (<a href="#6.5.2.1">6.5.2.1</a>), function-call parentheses () (<a href="#6.5.2.2">6.5.2.2</a>), and
the conditional operator ?: (<a href="#6.5.15">6.5.15</a>).
-<pre>
- Within each major subclause, the operators have the same precedence. Left- or right-associativity is
- indicated in each subclause by the syntax for the expressions discussed therein.</pre>
+ Within each major subclause, the operators have the same precedence. Left- or right-associativity is
+ indicated in each subclause by the syntax for the expressions discussed therein.
</small>
<p><small><a name="note75" href="#note75">75)</a> Allocated objects have no declared type.
</small>
</small>
<h4><a name="6.5.1" href="#6.5.1">6.5.1 Primary expressions</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
primary-expression:
identifier
constant
string-literal
- ( expression )</pre>
-<h6>Semantics</h6>
+ ( expression )
+</pre>
+<p><b>Semantics</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
postfix-expression:
primary-expression
postfix-expression [ expression ]
- postfix-expression ( argument-expression-listopt )
+ postfix-expression ( argument-expression-list<sub>opt</sub> )
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
- ( type-name ) { initializer-list , }</pre>
+ ( type-name ) { initializer-list , }
+</pre>
<pre>
argument-expression-list:
assignment-expression
- argument-expression-list , assignment-expression</pre>
+ argument-expression-list , assignment-expression
+</pre>
<h5><a name="6.5.2.1" href="#6.5.2.1">6.5.2.1 Array subscripting</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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''.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 4 -->
EXAMPLE Consider the array object defined by the declaration
<pre>
- int x[3][5];</pre>
+ int x[3][5];
+</pre>
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
<!--page 83 -->
<h5><a name="6.5.2.2" href="#6.5.2.2">6.5.2.2 Function calls</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 12 -->
EXAMPLE In the function call
<pre>
- (*pf[f1()]) (f2(), f3() + f4())</pre>
+ (*pf[f1()]) (f2(), f3() + f4())
+</pre>
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="6.5.2.3" href="#6.5.2.3">6.5.2.3 Structure and union members</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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 -->
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
struct s { int i; const int ci; };
struct s s;
const struct s cs;
- volatile struct s vs;</pre>
+ volatile struct s vs;
+</pre>
the various members have the types:
<pre>
s.i int
cs.i const int
cs.ci const int
vs.i volatile int
- vs.ci volatile const int</pre>
+ vs.ci volatile const int
+</pre>
/* ... */
if (u.n.alltypes == 1)
if (sin(u.nf.doublenode) == 0.0)
- /* ... */</pre>
+ /* ... */
+</pre>
The following is not a valid fragment (because the union type is not visible within function f):
<pre>
struct t1 { int m; };
} u;
/* ... */
return f(&u.s1, &u.s2);
- }</pre>
+ }
+</pre>
<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 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="6.5.2.4" href="#6.5.2.4">6.5.2.4 Postfix increment and decrement operators</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
The type name shall specify an object type or an array of unknown size, but not a variable
length array type.
<p><!--para 3 -->
If the compound literal occurs outside the body of a function, the initializer list shall
consist of constant expressions.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 9 -->
EXAMPLE 1 The file scope definition
<pre>
- int *p = (int []){2, 4};</pre>
+ int *p = (int []){2, 4};
+</pre>
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 = (int [2]){*p};
/*...*/
- }</pre>
+ }
+</pre>
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},
- (struct point){.x=3, .y=4});</pre>
+ (struct point){.x=3, .y=4});
+</pre>
Or, if drawline instead expected pointers to struct point:
<pre>
drawline(&(struct point){.x=1, .y=1},
- &(struct point){.x=3, .y=4});</pre>
+ &(struct point){.x=3, .y=4});
+</pre>
<p><!--para 12 -->
EXAMPLE 4 A read-only compound literal can be specified through constructions like:
<pre>
- (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}</pre>
+ (const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}
+</pre>
<pre>
"/tmp/fileXXXXXX"
(char []){"/tmp/fileXXXXXX"}
- (const char []){"/tmp/fileXXXXXX"}</pre>
+ (const char []){"/tmp/fileXXXXXX"}
+</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.
EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory
and can even be shared. For example,
<pre>
- (const char []){"abc"} == "abc"</pre>
+ (const char []){"abc"} == "abc"
+</pre>
might yield 1 if the literals' storage is shared.
<p><!--para 15 -->
<pre>
struct int_list { int car; struct int_list *cdr; };
struct int_list endless_zeros = {0, &endless_zeros};
- eval(endless_zeros);</pre>
+ eval(endless_zeros);
+</pre>
<p><!--para 16 -->
EXAMPLE 8 Each compound literal creates only a single object in a given scope:
q = p, p = &((struct s){ j++ });
if (j < 2) goto again;
return p == q && q->i == 1;
- }</pre>
+ }
+</pre>
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><b> Forward references</b>: type names (<a href="#6.7.6">6.7.6</a>), initialization (<a href="#6.7.8">6.7.8</a>).
<!--page 90 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
</small>
<h4><a name="6.5.3" href="#6.5.3">6.5.3 Unary operators</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
unary-expression:
sizeof unary-expression
sizeof ( type-name )
unary-operator: one of
- & * + - ~ !</pre>
+ & * + - ~ !
+</pre>
<h5><a name="6.5.3.1" href="#6.5.3.1">6.5.3.1 Prefix increment and decrement operators</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="6.5.3.3" href="#6.5.3.3">6.5.3.3 Unary arithmetic operators</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
integer type; of the ! operator, scalar type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
<!--page 92 -->
<h5><a name="6.5.3.4" href="#6.5.3.4">6.5.3.4 The sizeof operator</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
allocate and return a pointer to void. For example:
<pre>
extern void *alloc(size_t);
- double *dp = alloc(sizeof *dp);</pre>
+ double *dp = alloc(sizeof *dp);
+</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>
- sizeof array / sizeof array[0]</pre>
+ sizeof array / sizeof array[0]
+</pre>
<p><!--para 7 -->
EXAMPLE 3 In this example, the size of a variable length array is computed and returned from a
{
char b[n+3]; // variable length array
return sizeof b; // execution time sizeof
- }</pre>
+ }
+</pre>
size_t size;
size = fsize3(10); // fsize3 returns 13
return 0;
- }</pre>
+ }
+</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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
cast-expression:
unary-expression
- ( type-name ) cast-expression</pre>
-<h6>Constraints</h6>
+ ( type-name ) cast-expression
+</pre>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 94 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
multiplicative-expression:
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
- multiplicative-expression % cast-expression</pre>
-<h6>Constraints</h6>
+ multiplicative-expression % cast-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have arithmetic type. The operands of the % operator shall
have integer type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
<p><!--para 4 -->
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
additive-expression:
multiplicative-expression
additive-expression + multiplicative-expression
- additive-expression - multiplicative-expression</pre>
-<h6>Constraints</h6>
+ additive-expression - multiplicative-expression
+</pre>
+<p><b>Constraints</b>
<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.)
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 4 -->
If both operands have arithmetic type, the usual arithmetic conversions are performed on
them.
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.
-<p><!--para 11 -->
<pre>
{
int n = 4, m = 3;
p += 1; // p == &a[1]
(*p)[2] = 99; // a[1][2] == 99
n = p - a; // n == 1
- }</pre>
+ }
+</pre>
+<p><!--para 11 -->
If array a in the above example were declared to be an array of known constant size, and pointer p were
declared to be a pointer to an array of the same known constant size (pointing to a), the results would be
the same.
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.5.7" href="#6.5.7">6.5.7 Bitwise shift operators</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
shift-expression:
additive-expression
shift-expression << additive-expression
- shift-expression >> additive-expression</pre>
-<h6>Constraints</h6>
+ shift-expression >> additive-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have integer type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
relational-expression:
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
- relational-expression >= shift-expression</pre>
-<h6>Constraints</h6>
+ relational-expression >= shift-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
One of the following shall hold:
<ul>
<li> both operands are pointers to qualified or unqualified versions of compatible
incomplete types.
</ul>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
If both of the operands have arithmetic type, the usual arithmetic conversions are
performed.
(greater than or equal to) shall yield 1 if the specified relation is true and 0 if it is false.<sup><a href="#note92"><b>92)</b></a></sup>
The result has type int.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
equality-expression:
relational-expression
equality-expression == relational-expression
- equality-expression != relational-expression</pre>
-<h6>Constraints</h6>
+ equality-expression != relational-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
One of the following shall hold:
<ul>
qualified or unqualified version of void; or
<li> one operand is a pointer and the other is a null pointer constant.
</ul>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.5.10" href="#6.5.10">6.5.10 Bitwise AND operator</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
AND-expression:
equality-expression
- AND-expression & equality-expression</pre>
-<h6>Constraints</h6>
+ AND-expression & equality-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have integer type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
<p><!--para 4 -->
<!--page 100 -->
<h4><a name="6.5.11" href="#6.5.11">6.5.11 Bitwise exclusive OR operator</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
exclusive-OR-expression:
AND-expression
- exclusive-OR-expression ^ AND-expression</pre>
-<h6>Constraints</h6>
+ exclusive-OR-expression ^ AND-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have integer type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
<p><!--para 4 -->
operands is set).
<h4><a name="6.5.12" href="#6.5.12">6.5.12 Bitwise inclusive OR operator</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
inclusive-OR-expression:
exclusive-OR-expression
- inclusive-OR-expression | exclusive-OR-expression</pre>
-<h6>Constraints</h6>
+ inclusive-OR-expression | exclusive-OR-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have integer type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
<p><!--para 4 -->
<!--page 101 -->
<h4><a name="6.5.13" href="#6.5.13">6.5.13 Logical AND operator</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
logical-AND-expression:
inclusive-OR-expression
- logical-AND-expression && inclusive-OR-expression</pre>
-<h6>Constraints</h6>
+ logical-AND-expression && inclusive-OR-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have scalar type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
logical-OR-expression:
logical-AND-expression
- logical-OR-expression || logical-AND-expression</pre>
-<h6>Constraints</h6>
+ logical-OR-expression || logical-AND-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Each of the operands shall have scalar type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
<!--page 102 -->
<h4><a name="6.5.15" href="#6.5.15">6.5.15 Conditional operator</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
conditional-expression:
logical-OR-expression
- logical-OR-expression ? expression : conditional-expression</pre>
-<h6>Constraints</h6>
+ logical-OR-expression ? expression : conditional-expression
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
The first operand shall have scalar type.
<p><!--para 3 -->
<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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
const int *c_ip;
volatile int *v_ip;
int *ip;
- const char *c_cp;</pre>
+ const char *c_cp;
+</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>
c_ip v_ip const volatile int *
vp c_cp const void *
ip c_ip const int *
- vp ip void *</pre>
+ vp ip void *
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
assignment-expression:
conditional-expression
unary-expression assignment-operator assignment-expression
assignment-operator: one of
- = *= /= %= += -= <<= >>= &= ^= |=</pre>
-<h6>Constraints</h6>
+ = *= /= %= += -= <<= >>= &= ^= |=
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
An assignment operator shall have a modifiable lvalue as its left operand.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 104 -->
<h5><a name="6.5.16.1" href="#6.5.16.1">6.5.16.1 Simple assignment</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
One of the following shall hold:<sup><a href="#note96"><b>96)</b></a></sup>
<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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
char c;
/* ... */
if ((c = f()) == -1)
- /* ... */</pre>
+ /* ... */
+</pre>
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
char c;
int i;
long l;
- l = (c = i);</pre>
+ l = (c = i);
+</pre>
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.
const char c = 'A';
cpp = &p; // constraint violation
*cpp = &c; // valid
- *p = 0; // valid</pre>
+ *p = 0; // valid
+</pre>
The first assignment is unsafe because it would allow the following valid code to attempt to change the
value of the const object c.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="6.5.16.2" href="#6.5.16.2">6.5.16.2 Compound assignment</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
expression:
assignment-expression
- expression , assignment-expression</pre>
-<h6>Semantics</h6>
+ expression , assignment-expression
+</pre>
+<p><b>Semantics</b>
<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>
- f(a, (t=3, t+2), c)</pre>
+ f(a, (t=3, t+2), c)
+</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>).
<!--page 107 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
constant-expression:
- conditional-expression</pre>
-<h6>Description</h6>
+ conditional-expression
+</pre>
+<p><b>Description</b>
<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.
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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 4 -->
Each constant expression shall evaluate to a constant that is in the range of representable
values for its type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 109 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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="note100" href="#note100">100)</a> Thus, in the following initialization,
<pre>
- static int i = 2 || 1 / 0;</pre>
+ static int i = 2 || 1 / 0;
+</pre>
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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
declaration:
- declaration-specifiers init-declarator-listopt ;
+ declaration-specifiers init-declarator-list<sub>opt</sub> ;
declaration-specifiers:
- storage-class-specifier declaration-specifiersopt
- type-specifier declaration-specifiersopt
- type-qualifier declaration-specifiersopt
- function-specifier declaration-specifiersopt
+ 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>
init-declarator-list:
init-declarator
init-declarator-list , init-declarator
init-declarator:
declarator
- declarator = initializer</pre>
-<h6>Constraints</h6>
+ declarator = initializer
+</pre>
+<p><b>Constraints</b>
<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 4 -->
All declarations in the same scope that refer to the same object or function shall specify
compatible types.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
storage-class-specifier:
extern
static
auto
- register</pre>
-<h6>Constraints</h6>
+ register
+</pre>
+<p><b>Constraints</b>
<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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
or union member objects.
<p><b> Forward references</b>: type definitions (<a href="#6.7.7">6.7.7</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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,
</small>
<h4><a name="6.7.2" href="#6.7.2">6.7.2 Type specifiers</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
type-specifier:
_Complex
struct-or-union-specifier *
enum-specifier
- typedef-name</pre>
-<h6>Constraints</h6>
+ typedef-name
+</pre>
+<p><b>Constraints</b>
<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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 113 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
struct-or-union-specifier:
- struct-or-union identifieropt { struct-declaration-list }
+ struct-or-union identifier<sub>opt</sub> { struct-declaration-list }
struct-or-union identifier
struct-or-union:
struct
struct-declaration:
specifier-qualifier-list struct-declarator-list ;
specifier-qualifier-list:
- type-specifier specifier-qualifier-listopt
- type-qualifier specifier-qualifier-listopt
+ type-specifier specifier-qualifier-list<sub>opt</sub>
+ type-qualifier specifier-qualifier-list<sub>opt</sub>
struct-declarator-list:
struct-declarator
struct-declarator-list , struct-declarator
struct-declarator:
declarator
- declaratoropt : constant-expression</pre>
-<h6>Constraints</h6>
+ declarator<sub>opt</sub> : constant-expression
+</pre>
+<p><b>Constraints</b>
<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 -->
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 17 -->
EXAMPLE After the declaration:
<pre>
- struct s { int n; double d[]; };</pre>
+ struct s { int n; double d[]; };
+</pre>
the structure struct s has a flexible array member d. A typical way to use this is:
<pre>
int m = /* some value */;
- struct s *p = malloc(sizeof (struct s) + sizeof (double [m]));</pre>
+ struct s *p = malloc(sizeof (struct s) + sizeof (double [m]));
+</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 { int n; double d[m]; } *p;</pre>
+ struct { int n; double d[m]; } *p;
+</pre>
(there are circumstances in which this equivalence is broken; in particular, the offsets of member d might
not be the same).
<p><!--para 18 -->
struct s t1 = { 0 }; // valid
struct s t2 = { 1, { <a href="#4.2">4.2</a> }}; // invalid
t1.n = 4; // valid
- t1.d[0] = <a href="#4.2">4.2</a>; // might be undefined behavior</pre>
+ t1.d[0] = <a href="#4.2">4.2</a>; // might be undefined behavior
+</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>
- sizeof (struct s) >= offsetof(struct s, d) + sizeof (double)</pre>
+ sizeof (struct s) >= offsetof(struct s, d) + sizeof (double)
+</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>
- struct ss { int n; };</pre>
+ struct ss { int n; };
+</pre>
the expressions:
<pre>
sizeof (struct s) >= sizeof (struct ss)
- sizeof (struct s) >= offsetof(struct s, d)</pre>
+ sizeof (struct s) >= offsetof(struct s, d)
+</pre>
are always equal to 1.
<p><!--para 20 -->
If sizeof (double) is 8, then after the following code is executed:
struct s *s1;
struct s *s2;
s1 = malloc(sizeof (struct s) + 64);
- s2 = malloc(sizeof (struct s) + 46);</pre>
+ s2 = malloc(sizeof (struct s) + 46);
+</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:
-<p><!--para 21 -->
<pre>
struct { int n; double d[8]; } *s1;
- struct { int n; double d[5]; } *s2;</pre>
+ struct { int n; double d[5]; } *s2;
+</pre>
+<p><!--para 21 -->
Following the further successful assignments:
<pre>
s1 = malloc(sizeof (struct s) + 10);
- s2 = malloc(sizeof (struct s) + 6);</pre>
+ s2 = malloc(sizeof (struct s) + 6);
+</pre>
they then behave as if the declarations were:
<pre>
- struct { int n; double d[1]; } *s1, *s2;</pre>
+ struct { int n; double d[1]; } *s1, *s2;
+</pre>
and:
-<p><!--para 22 -->
<pre>
double *dp;
dp = &(s1->d[0]); // valid
*dp = 42; // valid
dp = &(s2->d[0]); // valid
- *dp = 42; // undefined behavior</pre>
+ *dp = 42; // undefined behavior
+</pre>
+<p><!--para 22 -->
The assignment:
<pre>
- *s1 = *s2;</pre>
+ *s1 = *s2;
+</pre>
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 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
</small>
<h5><a name="6.7.2.2" href="#6.7.2.2">6.7.2.2 Enumeration specifiers</a></h5>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
enum-specifier:
- enum identifieropt { enumerator-list }
- enum identifieropt { enumerator-list , }
+ enum identifier<sub>opt</sub> { enumerator-list }
+ enum identifier<sub>opt</sub> { enumerator-list , }
enum identifier
enumerator-list:
enumerator
enumerator-list , enumerator
enumerator:
enumeration-constant
- enumeration-constant = constant-expression</pre>
-<h6>Constraints</h6>
+ enumeration-constant = constant-expression
+</pre>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
col = claret;
cp = &col;
if (*cp != burgundy)
- /* ... */</pre>
+ /* ... */
+</pre>
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
</small>
<h5><a name="6.7.2.3" href="#6.7.2.3">6.7.2.3 Tags</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
A specific type shall have its content defined at most once.
<p><!--para 2 -->
<p><!--para 3 -->
A type specifier of the form
<pre>
- enum identifier</pre>
+ enum identifier
+</pre>
without an enumerator list shall only appear after the type it specifies is complete.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 6 -->
A type specifier of the form
<pre>
- struct-or-union identifieropt { struct-declaration-list }</pre>
+ struct-or-union identifier<sub>opt</sub> { struct-declaration-list }
+</pre>
or
<pre>
- enum identifier { enumerator-list }</pre>
+ enum identifier { enumerator-list }
+</pre>
or
<pre>
- enum identifier { enumerator-list , }</pre>
+ enum identifier { enumerator-list , }
+</pre>
declares a structure, union, or enumerated type. The list defines the structure content,
<!--page 119 -->
<p><!--para 7 -->
A declaration of the form
<pre>
- struct-or-union identifier ;</pre>
+ struct-or-union identifier ;
+</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>
- struct-or-union identifier</pre>
+ struct-or-union identifier
+</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
- declares the identifier as the tag of that type.113)
+ declares the identifier as the tag of that type.<sup><a href="#note113"><b>113)</b></a></sup>
<p><!--para 9 -->
If a type specifier of the form
<pre>
- struct-or-union identifier</pre>
+ struct-or-union identifier
+</pre>
or
<pre>
- enum identifier</pre>
+ enum identifier
+</pre>
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.
struct tnode {
int count;
struct tnode *left, *right;
- };</pre>
+ };
+</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>
- struct tnode s, *sp;</pre>
+ struct tnode s, *sp;
+</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
int count;
TNODE *left, *right;
};
- TNODE s, *sp;</pre>
+ TNODE s, *sp;
+</pre>
<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
- struct s2 { struct s1 *s1p; /* ... */ }; // D2</pre>
+ struct s2 { struct s1 *s1p; /* ... */ }; // D2
+</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>
- struct s2;</pre>
+ struct s2;
+</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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.7.3" href="#6.7.3">6.7.3 Type qualifiers</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
type-qualifier:
const
restrict
- volatile</pre>
-<h6>Constraints</h6>
+ volatile
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Types other than pointer types derived from object or incomplete types shall not be
restrict-qualified.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 10 -->
EXAMPLE 1 An object declared
<pre>
- extern const volatile int real_time_clock;</pre>
+ extern const volatile int real_time_clock;
+</pre>
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 = a[0]; // invalid: a[0] has type ''const int *''</pre>
+ pi = a[0]; // invalid: a[0] has type ''const int *''
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
<pre>
int * restrict a;
int * restrict b;
- extern int c[];</pre>
+ extern int c[];
+</pre>
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.
{
while (n-- > 0)
*p++ = *q++;
- }</pre>
+ }
+</pre>
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
- }</pre>
+ }
+</pre>
<p><!--para 10 -->
EXAMPLE 3 The function parameter declarations
int i;
for (i = 0; i < n; i++)
p[i] = q[i] + r[i];
- }</pre>
+ }
+</pre>
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 -->
-<p><!--para 12 -->
<pre>
{
int * restrict p1;
p1 = q2; // undefined behavior
p2 = q2; // undefined behavior
}
- }</pre>
+ }
+</pre>
+<p><!--para 12 -->
The one exception allows the value of a restricted pointer to be carried out of the block in which it (or, more
precisely, the ordinary identifier used to designate it) is declared when that block finishes execution. For
example, this permits new_vector to return a vector.
t.n = n;
t.v = malloc(n * sizeof (float));
return t;
- }</pre>
+ }
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.7.4" href="#6.7.4">6.7.4 Function specifiers</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
function-specifier:
- inline</pre>
-<h6>Constraints</h6>
+ inline
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
Function specifiers shall be used only in the declaration of an identifier for a function.
<p><!--para 3 -->
<p><!--para 4 -->
In a hosted environment, the inline function specifier shall not appear in a declaration
of main.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
-<p><!--para 8 -->
<pre>
inline double fahr(double t)
{
{
/* A translator may perform inline substitutions */
return is_fahr ? cels(temp) : fahr(temp);
- }</pre>
+ }
+</pre>
+<p><!--para 8 -->
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
<!--page 126 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.7.5" href="#6.7.5">6.7.5 Declarators</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
declarator:
- pointeropt direct-declarator
+ pointer<sub>opt</sub> direct-declarator
direct-declarator:
identifier
( declarator )
- direct-declarator [ type-qualifier-listopt assignment-expressionopt ]
- direct-declarator [ static type-qualifier-listopt assignment-expression ]
+ direct-declarator [ type-qualifier-list<sub>opt</sub> assignment-expression<sub>opt</sub> ]
+ direct-declarator [ static type-qualifier-list<sub>opt</sub> assignment-expression ]
direct-declarator [ type-qualifier-list static assignment-expression ]
- direct-declarator [ type-qualifier-listopt * ]
+ direct-declarator [ type-qualifier-list<sub>opt</sub> * ]
direct-declarator ( parameter-type-list )
- direct-declarator ( identifier-listopt )
+ direct-declarator ( identifier-list<sub>opt</sub> )
pointer:
- * type-qualifier-listopt
- * type-qualifier-listopt pointer
+ * type-qualifier-list<sub>opt</sub>
+ * type-qualifier-list<sub>opt</sub> pointer
type-qualifier-list:
type-qualifier
type-qualifier-list type-qualifier
parameter-list , parameter-declaration
parameter-declaration:
declaration-specifiers declarator
- declaration-specifiers abstract-declaratoropt
+ declaration-specifiers abstract-declarator<sub>opt</sub>
identifier-list:
identifier
- identifier-list , identifier</pre>
-<h6>Semantics</h6>
+ identifier-list , identifier
+</pre>
+<p><b>Semantics</b>
<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 4 -->
In the following subclauses, consider a declaration
<pre>
- T D1</pre>
+ T D1
+</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>
- identifier</pre>
+ identifier
+</pre>
then the type specified for ident is T .
<p><!--para 6 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
- ( D )</pre>
+ ( D )
+</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.
- Implementation limits
+<p><b>Implementation limits</b>
<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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 1 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
- * type-qualifier-listopt D</pre>
+ * type-qualifier-list<sub>opt</sub> D
+</pre>
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.
<!--page 128 -->
<pre>
const int *ptr_to_constant;
- int *const constant_ptr;</pre>
+ int *const constant_ptr;
+</pre>
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
type ''pointer to int''.
<pre>
typedef int *int_ptr;
- const int_ptr constant_ptr;</pre>
+ const int_ptr constant_ptr;
+</pre>
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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
If, in the declaration ''T D1'', D1 has one of the forms:
<pre>
- D[ type-qualifier-listopt assignment-expressionopt ]
- D[ static type-qualifier-listopt assignment-expression ]
+ 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 ]
- D[ type-qualifier-listopt * ]</pre>
+ D[ type-qualifier-list<sub>opt</sub> * ]
+</pre>
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.)
<p><!--para 7 -->
EXAMPLE 1
<pre>
- float fa[11], *afp[17];</pre>
+ float fa[11], *afp[17];
+</pre>
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;
- extern int y[];</pre>
+ extern int y[];
+</pre>
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
- }</pre>
+ }
+</pre>
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
- }</pre>
+ }
+</pre>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
A function declarator shall not specify a return type that is a function type or an array
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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
- D( parameter-type-list )</pre>
+ D( parameter-type-list )
+</pre>
or
<!--page 131 -->
<pre>
- D( identifier-listopt )</pre>
+ D( identifier-list<sub>opt</sub> )
+</pre>
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 ''.
<p><!--para 16 -->
EXAMPLE 1 The declaration
<pre>
- int f(void), *fip(), (*pfi)();</pre>
+ int f(void), *fip(), (*pfi)();
+</pre>
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
<p><!--para 18 -->
EXAMPLE 2 The declaration
<pre>
- int (*apfi[3])(int *x, int *y);</pre>
+ int (*apfi[3])(int *x, int *y);
+</pre>
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.
<p><!--para 19 -->
EXAMPLE 3 The declaration
<pre>
- int (*fpfi(int (*)(long), int))(int, ...);</pre>
+ int (*fpfi(int (*)(long), int))(int, ...);
+</pre>
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;
- }</pre>
+ }
+</pre>
<p><!--para 21 -->
EXAMPLE 5 The following are all compatible function prototype declarators.
double maximum(int n, int m, double a[n][m]);
double maximum(int n, int m, double a[*][*]);
double maximum(int n, int m, double a[ ][*]);
- double maximum(int n, int m, double a[ ][m]);</pre>
+ double maximum(int n, int m, double a[ ][m]);
+</pre>
as are:
<pre>
void f(double (* restrict a)[5]);
void f(double a[restrict][5]);
void f(double a[restrict 3][5]);
- void f(double a[restrict static 3][5]);</pre>
+ void f(double a[restrict static 3][5]);
+</pre>
(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 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
</small>
<h4><a name="6.7.6" href="#6.7.6">6.7.6 Type names</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
type-name:
- specifier-qualifier-list abstract-declaratoropt
+ specifier-qualifier-list abstract-declarator<sub>opt</sub>
abstract-declarator:
pointer
- pointeropt direct-abstract-declarator
+ pointer<sub>opt</sub> direct-abstract-declarator
direct-abstract-declarator:
( abstract-declarator )
- direct-abstract-declaratoropt [ type-qualifier-listopt
- assignment-expressionopt ]
- direct-abstract-declaratoropt [ static type-qualifier-listopt
+ direct-abstract-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>
assignment-expression ]
- direct-abstract-declaratoropt [ type-qualifier-list static
+ direct-abstract-declarator<sub>opt</sub> [ type-qualifier-list static
assignment-expression ]
- direct-abstract-declaratoropt [ * ]
- direct-abstract-declaratoropt ( parameter-type-listopt )</pre>
-<h6>Semantics</h6>
+ direct-abstract-declarator<sub>opt</sub> [ * ]
+ direct-abstract-declarator<sub>opt</sub> ( parameter-type-list<sub>opt</sub> )
+</pre>
+<p><b>Semantics</b>
<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
(e) int (*)[*]
(f) int *()
(g) int (*)(void)
- (h) int (*const [])(unsigned int, ...)</pre>
+ (h) int (*const [])(unsigned int, ...)
+</pre>
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
<!--page 135 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
typedef-name:
- identifier</pre>
-<h6>Constraints</h6>
+ identifier
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
If a typedef name specifies a variably modified type then it shall have block scope.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
synonym for the type so specified. That is, in the following declarations:
<pre>
typedef T type_ident;
- type_ident D;</pre>
+ type_ident D;
+</pre>
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
EXAMPLE 1 After
<pre>
typedef int MILES, KLICKSP();
- typedef struct { double hi, lo; } range;</pre>
+ typedef struct { double hi, lo; } range;
+</pre>
the constructions
<pre>
MILES distance;
extern KLICKSP *metricp;
range x;
- range z, *zp;</pre>
+ range z, *zp;
+</pre>
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;
- typedef struct s2 { int x; } t2, *tp2;</pre>
+ typedef struct s2 { int x; } t2, *tp2;
+</pre>
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 -->
unsigned t:4;
const t:5;
plain r:5;
- };</pre>
+ };
+</pre>
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
in an inner scope by
<pre>
t f(t (t));
- long t;</pre>
+ long t;
+</pre>
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 *);
- pfv signal(int, pfv);</pre>
+ pfv signal(int, pfv);
+</pre>
<p><!--para 8 -->
EXAMPLE 5 If a typedef name denotes a variable length array type, the length of the array is fixed at the
int b[n]; // a and b are different sizes
for (int i = 1; i < n; i++)
a[i-1] = b[i];
- }</pre>
+ }
+</pre>
<h4><a name="6.7.8" href="#6.7.8">6.7.8 Initialization</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
initializer:
{ initializer-list }
{ initializer-list , }
initializer-list:
- designationopt initializer
- initializer-list , designationopt initializer
+ designation<sub>opt</sub> initializer
+ initializer-list , designation<sub>opt</sub> initializer
designation:
designator-list =
designator-list:
designator-list designator
designator:
[ constant-expression ]
- . identifier</pre>
-<h6>Constraints</h6>
+ . identifier
+</pre>
+<p><b>Constraints</b>
<p><!--para 2 -->
No initializer shall attempt to provide a value for an object not contained within the entity
being initialized.
<p><!--para 6 -->
If a designator has the form
<pre>
- [ constant-expression ]</pre>
+ [ constant-expression ]
+</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>
- . identifier</pre>
+ . identifier
+</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 -->
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 8 -->
An initializer specifies the initial value stored in an object.
<p><!--para 9 -->
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>;
- double complex c = 5 + 3 * I;</pre>
+ double complex c = 5 + 3 * I;
+</pre>
define and initialize i with the value 3 and c with the value 5.0 + i3.0.
<p><!--para 25 -->
EXAMPLE 2 The declaration
<pre>
- int x[] = { 1, 3, 5 };</pre>
+ int x[] = { 1, 3, 5 };
+</pre>
defines and initializes x as a one-dimensional array object that has three elements, as no size was specified
and there are three initializers.
{ 1, 3, 5 },
{ 2, 4, 6 },
{ 3, 5, 7 },
- };</pre>
+ };
+</pre>
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>
+ };
+</pre>
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>
+ };
+</pre>
initializes the first column of z as specified and initializes the rest with zeros.
<p><!--para 28 -->
EXAMPLE 5 The declaration
<pre>
- struct { int a[3], b; } w[] = { { 1 }, 2 };</pre>
+ struct { int a[3], b; } w[] = { { 1 }, 2 };
+</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.
{ 1 },
{ 2, 3 },
{ 4, 5, 6 }
- };</pre>
+ };
+</pre>
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
1, 0, 0, 0, 0, 0,
2, 3, 0, 0, 0, 0,
4, 5, 6
- };</pre>
+ };
+</pre>
or by:
<pre>
short q[4][3][2] = {
{ 4, 5 },
{ 6 },
}
- };</pre>
+ };
+</pre>
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
EXAMPLE 7 One form of initialization that completes array types involves typedef names. Given the
declaration
<pre>
- typedef int A[]; // OK - declared with block scope</pre>
+ typedef int A[]; // OK - declared with block scope
+</pre>
the declaration
<pre>
- A a = { 1, 2 }, b = { 3, 4, 5 };</pre>
+ A a = { 1, 2 }, b = { 3, 4, 5 };
+</pre>
is identical to
<pre>
- int a[] = { 1, 2 }, b[] = { 3, 4, 5 };</pre>
+ int a[] = { 1, 2 }, b[] = { 3, 4, 5 };
+</pre>
due to the rules for incomplete types.
<!--page 142 -->
<p><!--para 32 -->
EXAMPLE 8 The declaration
<pre>
- char s[] = "abc", t[3] = "abc";</pre>
+ char s[] = "abc", t[3] = "abc";
+</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' },
- t[] = { 'a', 'b', 'c' };</pre>
+ t[] = { 'a', 'b', 'c' };
+</pre>
The contents of the arrays are modifiable. On the other hand, the declaration
<pre>
- char *p = "abc";</pre>
+ char *p = "abc";
+</pre>
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",
- };</pre>
+ };
+</pre>
<p><!--para 34 -->
EXAMPLE 10 Structure members can be initialized to nonzero values without depending on their order:
<pre>
- div_t answer = { .quot = 2, .rem = -1 };</pre>
+ div_t answer = { .quot = 2, .rem = -1 };
+</pre>
<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[] =
- { [0].a = {1}, [1].a[0] = 2 };</pre>
+ { [0].a = {1}, [1].a[0] = 2 };
+</pre>
<p><!--para 36 -->
EXAMPLE 12 Space can be ''allocated'' from both ends of an array by using a single designator:
-<p><!--para 37 -->
<pre>
int a[MAX] = {
1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
- };</pre>
+ };
+</pre>
+<p><!--para 37 -->
In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less
than ten, some of the values provided by the first five initializers will be overridden by the second five.
<p><!--para 38 -->
EXAMPLE 13 Any member of a union can be initialized:
<pre>
- union { /* ... */ } u = { .any_member = 42 };</pre>
+ union { /* ... */ } u = { .any_member = 42 };
+</pre>
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>).
<!--page 143 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
</small>
<h3><a name="6.8" href="#6.8">6.8 Statements and blocks</a></h3>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
statement:
expression-statement
selection-statement
iteration-statement
- jump-statement</pre>
-<h6>Semantics</h6>
+ jump-statement
+</pre>
+<p><b>Semantics</b>
<p><!--para 2 -->
A statement specifies an action to be performed. Except as indicated, statements are
executed in sequence.
(<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
labeled-statement:
identifier : statement
case constant-expression : statement
- default : statement</pre>
-<h6>Constraints</h6>
+ default : statement
+</pre>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
compound-statement:
- { block-item-listopt }
+ { block-item-list<sub>opt</sub> }
block-item-list:
block-item
block-item-list block-item
block-item:
declaration
- statement</pre>
-<h6>Semantics</h6>
+ statement
+</pre>
+<p><b>Semantics</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
expression-statement:
- expressionopt ;</pre>
-<h6>Semantics</h6>
+ expression<sub>opt</sub> ;
+</pre>
+<p><b>Semantics</b>
<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>
<pre>
int p(int);
/* ... */
- (void)p(0);</pre>
+ (void)p(0);
+</pre>
char *s;
/* ... */
while (*s++ != '\0')
- ;</pre>
+ ;
+</pre>
a null statement is used to supply an empty loop body to the iteration statement.
<p><!--para 6 -->
}
/* ... */
end_loop1: ;
- }</pre>
+ }
+</pre>
<p><b> Forward references</b>: iteration statements (<a href="#6.8.5">6.8.5</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
selection-statement:
if ( expression ) statement
if ( expression ) statement else statement
- switch ( expression ) statement</pre>
-<h6>Semantics</h6>
+ switch ( expression ) statement
+</pre>
+<p><b>Semantics</b>
<p><!--para 2 -->
A selection statement selects among a set of statements depending on the value of a
controlling expression.
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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
The controlling expression of an if statement shall have scalar type.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
syntax.
<h5><a name="6.8.4.2" href="#6.8.4.2">6.8.4.2 The switch statement</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
The controlling expression of a switch statement shall have integer type.
<p><!--para 2 -->
(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.)
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
- Implementation limits
+<p><b>Implementation limits</b>
<p><!--para 6 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, the implementation may limit the number of case values in a
switch statement.
/* falls through into default code */
default:
printf("%d\n", i);
- }</pre>
+ }
+</pre>
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
iteration-statement:
while ( expression ) statement
do statement while ( expression ) ;
- for ( expressionopt ; expressionopt ; expressionopt ) statement
- for ( declaration expressionopt ; expressionopt ) statement</pre>
-<h6>Constraints</h6>
+ 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>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 148 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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><!--para 1 -->
The statement
<pre>
- for ( clause-1 ; expression-2 ; expression-3 ) statement</pre>
+ for ( clause-1 ; expression-2 ; expression-3 ) statement
+</pre>
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
Both clause-1 and expression-3 can be omitted. An omitted expression-2 is replaced by a
nonzero constant.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.8.6" href="#6.8.6">6.8.6 Jump statements</a></h4>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
jump-statement:
goto identifier ;
continue ;
break ;
- return expressionopt ;</pre>
-<h6>Semantics</h6>
+ return expression<sub>opt</sub> ;
+</pre>
+<p><b>Semantics</b>
<p><!--para 2 -->
A jump statement causes an unconditional jump to another place.
<!--page 149 -->
<h5><a name="6.8.6.1" href="#6.8.6.1">6.8.6.1 The goto statement</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 2 -->
A goto statement causes an unconditional jump to the statement prefixed by the named
label in the enclosing function.
<li> The general initialization code is too large to warrant duplication.
<li> The code to determine the next operation is at the head of the loop. (To allow it to be reached by
continue statements, for example.)
+<pre>
/* ... */
goto first_time;
for (;;) {
-<pre>
// determine next operation
/* ... */
if (need to reinitialize) {
continue;
}
// handle other operations
- /* ... */</pre>
+ /* ... */
}
+</pre>
<!--page 150 -->
</ol>
<p><!--para 4 -->
lab4:
a[j] = <a href="#6.6">6.6</a>;
}
- goto lab4; // invalid: going INTO scope of VLA.</pre>
+ goto lab4; // invalid: going INTO scope of VLA.
+</pre>
<h5><a name="6.8.6.2" href="#6.8.6.2">6.8.6.2 The continue statement</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
A continue statement shall appear only in or as a loop body.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
of the statements
- while (/* ... */) { do { for (/* ... */) {
<pre>
+ while (/* ... */) { do { for (/* ... */) {
/* ... */ /* ... */ /* ... */
continue; continue; continue;
- /* ... */ /* ... */ /* ... */</pre>
+ /* ... */ /* ... */ /* ... */
contin: ; contin: ; contin: ;
} } while (/* ... */); }
+</pre>
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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
A break statement shall appear only in or as a switch body or loop body.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 2 -->
A break statement terminates execution of the smallest enclosing switch or iteration
statement.
<!--page 151 -->
<h5><a name="6.8.6.4" href="#6.8.6.4">6.8.6.4 The return statement</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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.
return g.u1.f2;
}
/* ... */
- g.u2.f3 = f();</pre>
+ g.u2.f3 = f();
+</pre>
there is no undefined behavior, although there would be if the assignment were done directly (without using
a function call to fetch the value).
<!--page 152 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h3><a name="6.9" href="#6.9">6.9 External definitions</a></h3>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
translation-unit:
translation-unit external-declaration
external-declaration:
function-definition
- declaration</pre>
-<h6>Constraints</h6>
+ declaration
+</pre>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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''
<!--page 153 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<pre>
function-definition:
- declaration-specifiers declarator declaration-listopt compound-statement
+ declaration-specifiers declarator declaration-list<sub>opt</sub> compound-statement
declaration-list:
declaration
- declaration-list declaration</pre>
-<h6>Constraints</h6>
+ declaration-list declaration
+</pre>
+<p><b>Constraints</b>
<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>
<!--page 154 -->
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
extern int max(int a, int b)
{
return a > b ? a : b;
- }</pre>
+ }
+</pre>
extern is the storage-class specifier and int is the type specifier; max(int a, int b) is the
function declarator; and
<pre>
- { return a > b ? a : b; }</pre>
+ { return a > b ? a : b; }
+</pre>
is the function body. The following similar definition uses the identifier-list form for the parameter
declarations:
int a, b;
{
return a > b ? a : b;
- }</pre>
+ }
+</pre>
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.
<pre>
int f(void);
/* ... */
- g(f);</pre>
+ g(f);
+</pre>
Then the definition of g might read
<pre>
void g(int (*funcp)(void))
{
/* ... */
(*funcp)(); /* or funcp(); ... */
- }</pre>
+ }
+</pre>
or, equivalently,
<pre>
void g(int func(void))
{
/* ... */
func(); /* or (*func)(); ... */
- }</pre>
+ }
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note141" href="#note141">141)</a> The intent is that the type category in a function definition cannot be inherited from a typedef:
<pre>
F *e(void) { /* ... */ } // e returns a pointer to a function
F *((e))(void) { /* ... */ } // same: parentheses irrelevant
int (*fp)(void); // fp points to a function that has type F
- F *Fp; // Fp points to a function that has type F</pre>
+ F *Fp; // Fp points to a function that has type F
+</pre>
</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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 i5; // refers to previous, whose linkage is internal</pre>
+ extern int i5; // refers to previous, whose linkage is internal
+</pre>
<p><!--para 5 -->
EXAMPLE 2 If at the end of the translation unit containing
<pre>
- int i[];</pre>
+ int i[];
+</pre>
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>
-<h6>Syntax</h6>
+<p><b>Syntax</b>
<p><!--para 1 -->
<!--page 158 -->
<pre>
preprocessing-file:
- groupopt
+ group<sub>opt</sub>
group:
group-part
group group-part
text-line
# non-directive
if-section:
- if-group elif-groupsopt else-groupopt endif-line
+ if-group elif-groups<sub>opt</sub> else-group<sub>opt</sub> endif-line
if-group:
- # if constant-expression new-line groupopt
- # ifdef identifier new-line groupopt
- # ifndef identifier new-line groupopt
+ # if constant-expression new-line group<sub>opt</sub>
+ # ifdef identifier new-line group<sub>opt</sub>
+ # ifndef identifier new-line group<sub>opt</sub>
elif-groups:
elif-group
elif-groups elif-group
elif-group:
- # elif constant-expression new-line groupopt
+ # elif constant-expression new-line group<sub>opt</sub>
else-group:
- # else new-line groupopt
+ # else new-line group<sub>opt</sub>
endif-line:
# endif new-line
control-line:
# include pp-tokens new-line
# define identifier replacement-list new-line
- # define identifier lparen identifier-listopt )
+ # define identifier lparen identifier-list<sub>opt</sub> )
replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
# define identifier lparen identifier-list , ... )
replacement-list new-line
# undef identifier new-line
# line pp-tokens new-line
- # error pp-tokensopt new-line
- # pragma pp-tokensopt new-line
+ # error pp-tokens<sub>opt</sub> new-line
+ # pragma pp-tokens<sub>opt</sub> new-line
# new-line
text-line:
- pp-tokensopt new-line
+ pp-tokens<sub>opt</sub> new-line
non-directive:
pp-tokens new-line
lparen:
a ( character not immediately preceded by white-space
replacement-list:
- pp-tokensopt
+ pp-tokens<sub>opt</sub>
pp-tokens:
preprocessing-token
pp-tokens preprocessing-token
new-line:
- the new-line character</pre>
-<h6>Description</h6>
+ the new-line character
+</pre>
+<p><b>Description</b>
<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.
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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).
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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,
EXAMPLE In:
<pre>
#define EMPTY
- EMPTY # include <file.h></pre>
+ EMPTY # include <file.h>
+</pre>
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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
<!--page 160 -->
<pre>
- defined identifier</pre>
+ defined identifier
+</pre>
or
<pre>
- defined ( identifier )</pre>
+ defined ( identifier )
+</pre>
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>).
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 3 -->
Preprocessing directives of the forms
<pre>
- # if constant-expression new-line groupopt
- # elif constant-expression new-line groupopt</pre>
+ # if constant-expression new-line group<sub>opt</sub>
+ # elif constant-expression new-line group<sub>opt</sub>
+</pre>
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
<!--page 161 -->
<pre>
- # ifdef identifier new-line groupopt
- # ifndef identifier new-line groupopt</pre>
+ # ifdef identifier new-line group<sub>opt</sub>
+ # ifndef identifier new-line group<sub>opt</sub>
+</pre>
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
</small>
<p><small><a name="note146" href="#note146">146)</a> Thus, the constant expression in the following #if directive and if statement is not guaranteed to
evaluate to the same value in these two contexts.
+<pre>
#if 'z' - 'a' == 25
if ('z' - 'a' == 25)
+</pre>
</small>
<p><small><a name="note147" href="#note147">147)</a> As indicated by the syntax, a preprocessing token shall not follow a #else or #endif directive
</small>
<h4><a name="6.10.2" href="#6.10.2">6.10.2 Source file inclusion</a></h4>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
A #include directive shall identify a header or source file that can be processed by the
implementation.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 2 -->
A preprocessing directive of the form
<pre>
- # include <h-char-sequence> new-line</pre>
+ # include <h-char-sequence> new-line
+</pre>
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
<!--page 162 -->
<pre>
- # include "q-char-sequence" new-line</pre>
+ # include "q-char-sequence" new-line
+</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>
- # include <h-char-sequence> new-line</pre>
+ # include <h-char-sequence> new-line
+</pre>
with the identical contained sequence (including > characters, if any) from the original
directive.
<p><!--para 4 -->
A preprocessing directive of the form
<pre>
- # include pp-tokens new-line</pre>
+ # include pp-tokens new-line
+</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
EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following:
<pre>
#include <a href="#7.19"><stdio.h></a>
- #include "myprog.h"</pre>
+ #include "myprog.h"
+</pre>
<p><!--para 8 -->
EXAMPLE 2 This illustrates macro-replaced #include directives:
#else
#define INCFILE "versN.h"
#endif
- #include INCFILE</pre>
+ #include INCFILE
+</pre>
<p><b> Forward references</b>: macro replacement (<a href="#6.10.3">6.10.3</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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 6 -->
A parameter identifier in a function-like macro shall be uniquely declared within its
scope.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 9 -->
A preprocessing directive of the form
<pre>
- # define identifier replacement-list new-line</pre>
+ # define identifier replacement-list new-line
+</pre>
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
<p><!--para 10 -->
A preprocessing directive of the form
<pre>
- # define identifier lparen identifier-listopt ) replacement-list new-line
+ # define identifier lparen identifier-list<sub>opt</sub> ) replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
- # define identifier lparen identifier-list , ... ) replacement-list new-line</pre>
+ # define identifier lparen identifier-list , ... ) replacement-list new-line
+</pre>
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 ...).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
replace it.
<h5><a name="6.10.3.2" href="#6.10.3.2">6.10.3.2 The # operator</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
<!--page 166 -->
<h5><a name="6.10.3.3" href="#6.10.3.3">6.10.3.3 The ## operator</a></h5>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<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.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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
- // char p[] = "x ## y";</pre>
+ // char p[] = "x ## y";
+</pre>
The expansion produces, at various stages:
<pre>
join(x, y)
in_between(x hash_hash y)
in_between(x ## y)
mkstr(x ## y)
- "x ## y"</pre>
+ "x ## y"
+</pre>
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 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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><!--para 2 -->
A preprocessing directive of the form
<pre>
- # undef identifier new-line</pre>
+ # undef identifier new-line
+</pre>
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
- int table[TABSIZE];</pre>
+ int table[TABSIZE];
+</pre>
<p><!--para 4 -->
EXAMPLE 2 The following defines a function-like macro whose value is the maximum of its arguments.
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>
- #define max(a, b) ((a) > (b) ? (a) : (b))</pre>
+ #define max(a, b) ((a) > (b) ? (a) : (b))
+</pre>
The parentheses ensure that the arguments and the resulting expression are bound properly.
<!--page 168 -->
<p><!--para 5 -->
g(x+(3,4)-w) | h 5) & m
(f)^m(m);
p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };
- char c[2][6] = { str(hello), str() };</pre>
+ char c[2][6] = { str(hello), str() };
+</pre>
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, };
- char c[2][6] = { "hello", "" };</pre>
+ char c[2][6] = { "hello", "" };
+</pre>
<p><!--para 6 -->
EXAMPLE 4 To illustrate the rules for creating character string literals and concatenating tokens, the
== 0) str(: @\n), s);
#include xstr(INCFILE(2).h)
glue(HIGH, LOW);
- xglue(HIGH, LOW)</pre>
+ xglue(HIGH, LOW)
+</pre>
results in
<!--page 169 -->
<pre>
s);
#include "vers2.h" (after macro replacement, before file access)
"hello";
- "hello" ", world"</pre>
+ "hello" ", world"
+</pre>
or, after concatenation of the character string literals,
<pre>
printf("x1= %d, x2= %s", x1, x2);
s);
#include "vers2.h" (after macro replacement, before file access)
"hello";
- "hello, world"</pre>
+ "hello, world"
+</pre>
Space around the # and ## tokens in the macro definition is optional.
<p><!--para 7 -->
<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,
- 10, 11, 12, };</pre>
+ 10, 11, 12, };
+</pre>
<p><!--para 8 -->
EXAMPLE 6 To demonstrate the redefinition rules, the following sequence is valid.
#define FUNC_LIKE(a) ( a )
#define FUNC_LIKE( a )( /* note the white space */ \
a /* other stuff on this line
- */ )</pre>
+ */ )
+</pre>
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
- #define FUNC_LIKE(b) ( b ) // different parameter spelling</pre>
+ #define FUNC_LIKE(b) ( b ) // different parameter spelling
+</pre>
<p><!--para 9 -->
EXAMPLE 7 Finally, to show the variable argument list macro facilities:
debug("Flag");
debug("X = %d\n", x);
showlist(The first, second, and third items.);
- report(x>y, "x is %d but y is %d", x, y);</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"):
- printf("x is %d but y is %d", x, y));</pre>
+ printf("x is %d but y is %d", x, y));
+</pre>
<h4><a name="6.10.4" href="#6.10.4">6.10.4 Line control</a></h4>
-<h6>Constraints</h6>
+<p><b>Constraints</b>
<p><!--para 1 -->
The string literal of a #line directive, if present, shall be a character string literal.
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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 3 -->
A preprocessing directive of the form
<pre>
- # line digit-sequence new-line</pre>
+ # line digit-sequence new-line
+</pre>
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
<p><!--para 4 -->
A preprocessing directive of the form
<pre>
- # line digit-sequence "s-char-sequenceopt" new-line</pre>
+ # line digit-sequence "s-char-sequence<sub>opt</sub>" new-line
+</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>
- # line pp-tokens new-line</pre>
+ # line pp-tokens new-line
+</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
<!--page 171 -->
<h4><a name="6.10.5" href="#6.10.5">6.10.5 Error directive</a></h4>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 1 -->
A preprocessing directive of the form
<pre>
- # error pp-tokensopt new-line</pre>
+ # error pp-tokens<sub>opt</sub> new-line
+</pre>
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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 1 -->
A preprocessing directive of the form
<pre>
- # pragma pp-tokensopt new-line</pre>
+ # pragma pp-tokens<sub>opt</sub> new-line
+</pre>
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
#pragma STDC FENV_ACCESS on-off-switch
#pragma STDC CX_LIMITED_RANGE on-off-switch
on-off-switch: one of
- ON OFF DEFAULT</pre>
+ ON OFF DEFAULT
+</pre>
<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>).
<!--page 172 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h4><a name="6.10.7" href="#6.10.7">6.10.7 Null directive</a></h4>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 1 -->
A preprocessing directive of the form
<pre>
- # new-line</pre>
+ # new-line
+</pre>
has no effect.
<h4><a name="6.10.8" href="#6.10.8">6.10.8 Predefined macro names</a></h4>
<p><!--para 1 -->
The following macro names<sup><a href="#note154"><b>154)</b></a></sup> shall be defined by the implementation:
- __DATE__ The date of translation of the preprocessing translation unit: a character
-<pre>
+<dl>
+<dt> __DATE__ <dd>The date of translation of the preprocessing translation unit: a character
string literal of the form "Mmm dd yyyy", where the names of the
months are the same as those generated by the asctime function, and the
first character of dd is a space character if the value is less than 10. If the
date of translation is not available, an implementation-defined valid date
- shall be supplied.</pre>
- __FILE__ The presumed name of the current source file (a character string literal).<sup><a href="#note155"><b>155)</b></a></sup>
- __LINE__ The presumed line number (within the current source file) of the current
-<pre>
- source line (an integer constant).155)</pre>
- __STDC__ The integer constant 1, intended to indicate a conforming implementation.
- __STDC_HOSTED__ The integer constant 1 if the implementation is a hosted
-<pre>
- implementation or the integer constant 0 if it is not.</pre>
- __STDC_MB_MIGHT_NEQ_WC__ The integer constant 1, intended to indicate that, in
-<pre>
+ shall be supplied.
+<dt> __FILE__ <dd>The presumed name of the current source file (a character string literal).<sup><a href="#note155"><b>155)</b></a></sup>
+<dt> __LINE__ <dd>The presumed line number (within the current source file) of the current
+ source line (an integer constant).<sup><a href="#note155"><b>155)</b></a></sup>
+<dt> __STDC__ <dd>The integer constant 1, intended to indicate a conforming implementation.
+<dt> __STDC_HOSTED__ <dd>The integer constant 1 if the implementation is a hosted
+ implementation or the integer constant 0 if it is not.
+<dt> __STDC_MB_MIGHT_NEQ_WC__ <dd>The integer constant 1, intended to indicate that, in
the encoding for wchar_t, a member of the basic character set need not
have a code value equal to its value when used as the lone character in an
- integer character constant.</pre>
- __STDC_VERSION__ The integer constant 199901L.<sup><a href="#note156"><b>156)</b></a></sup>
- __TIME__ The time of translation of the preprocessing translation unit: a character
-<pre>
+ integer character constant.
+<dt> __STDC_VERSION__ <dd>The integer constant 199901L.<sup><a href="#note156"><b>156)</b></a></sup>
+<dt> __TIME__ <dd>The time of translation of the preprocessing translation unit: a character
string literal of the form "hh:mm:ss" as in the time generated by the
asctime function. If the time of translation is not available, an
- implementation-defined valid time shall be supplied.</pre>
-
+ implementation-defined valid time shall be supplied.
+</dl>
<!--page 173 -->
<p><!--para 2 -->
The following macro names are conditionally defined by the implementation:
- __STDC_IEC_559__ The integer constant 1, intended to indicate conformance to the
-<pre>
- specifications in <a href="#F">annex F</a> (IEC 60559 floating-point arithmetic).</pre>
- __STDC_IEC_559_COMPLEX__ The integer constant 1, intended to indicate
-<pre>
+<dl>
+<dt> __STDC_IEC_559__ <dd>The integer constant 1, intended to indicate conformance to the
+ specifications in <a href="#F">annex F</a> (IEC 60559 floating-point arithmetic).
+<dt> __STDC_IEC_559_COMPLEX__ <dd>The integer constant 1, intended to indicate
adherence to the specifications in informative <a href="#G">annex G</a> (IEC 60559
- compatible complex arithmetic).</pre>
- __STDC_ISO_10646__ An integer constant of the form yyyymmL (for example,
-<p><!--para 3 -->
-<pre>
+ compatible complex arithmetic).
+<dt> __STDC_ISO_10646__ <dd>An integer constant of the form yyyymmL (for example,
199712L). If this symbol is defined, then every character in the Unicode
required set, when stored in an object of type wchar_t, has the same
value as the short identifier of that character. The Unicode required set
consists of all the characters that are defined by ISO/IEC 10646, along with
all amendments and technical corrigenda, as of the specified year and
- month.</pre>
+ month.
+</dl>
+<p><!--para 3 -->
The values of the predefined macros (except for __FILE__ and __LINE__) remain
constant throughout the translation unit.
<p><!--para 4 -->
in any standard header.
<p><b> Forward references</b>: the asctime function (<a href="#7.23.3.1">7.23.3.1</a>), standard headers (<a href="#7.1.2">7.1.2</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
</small>
<h4><a name="6.10.9" href="#6.10.9">6.10.9 Pragma operator</a></h4>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<p><!--para 1 -->
A unary operator expression of the form:
<pre>
- _Pragma ( string-literal )</pre>
+ _Pragma ( string-literal )
+</pre>
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
<p><!--para 2 -->
EXAMPLE A directive of the form:
<pre>
- #pragma listing on "..\listing.dir"</pre>
+ #pragma listing on "..\listing.dir"
+</pre>
can also be expressed as:
<!--page 174 -->
<pre>
- _Pragma ( "listing on \"..\\listing.dir\"" )</pre>
+ _Pragma ( "listing on \"..\\listing.dir\"" )
+</pre>
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)
- LISTING ( ..\listing.dir )</pre>
+ LISTING ( ..\listing.dir )
+</pre>
<h3><a name="6.11" href="#6.11">6.11 Future language directions</a></h3>
<!--page 177 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
include type qualifiers, unless explicitly stated otherwise.
<p><!--para 2 -->
The standard headers are
-<p><!--para 3 -->
<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>
- <a href="#7.7"><float.h></a> <a href="#7.13"><setjmp.h></a> <a href="#7.19"><stdio.h></a> <a href="#7.25"><wctype.h></a></pre>
+ <a href="#7.7"><float.h></a> <a href="#7.13"><setjmp.h></a> <a href="#7.19"><stdio.h></a> <a href="#7.25"><wctype.h></a>
+</pre>
+<p><!--para 3 -->
If a file with the same name as one of the above < and > delimited sequences, not
provided as part of the implementation, is placed in any of the standard places that are
searched for included source files, the behavior is undefined.
<!--page 178 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
#include <a href="#7.20"><stdlib.h></a>
const char *str;
/* ... */
- i = atoi(str);</pre>
+ i = atoi(str);
+</pre>
<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;
/* ... */
- i = atoi(str);</pre>
+ i = atoi(str);
+</pre>
or
<pre>
#include <a href="#7.20"><stdlib.h></a>
const char *str;
/* ... */
- i = (atoi)(str);</pre>
+ i = (atoi)(str);
+</pre>
<li> by explicit declaration
<!--page 181 -->
<pre>
extern int atoi(const char *);
const char *str;
/* ... */
- i = atoi(str);</pre>
+ i = atoi(str);
+</pre>
</ul>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
appropriate header could specify
<pre>
- #define abs(x) _BUILTIN_abs(x)</pre>
+ #define abs(x) _BUILTIN_abs(x)
+</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>
- #undef abs</pre>
+ #undef abs
+</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.
<p><small><a name="note164" href="#note164">164)</a> Thus, a signal handler cannot, in general, call standard library functions.
</small>
-<h3><a name="7.2" href="#7.2">7.2 Diagnostics <assert.h></a></h3>
+<h3><a name="7.2" href="#7.2">7.2 Diagnostics <assert.h></a></h3>
<p><!--para 1 -->
The header <a href="#7.2"><assert.h></a> defines the assert macro and refers to another macro,
<pre>
- NDEBUG</pre>
+ NDEBUG
+</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>
- #define assert(ignore) ((void)0)</pre>
+ #define assert(ignore) ((void)0)
+</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 -->
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.2"><assert.h></a>
- void assert(scalar expression);</pre>
-<h6>Description</h6>
+ void assert(scalar expression);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>).
<!--page 182 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h3><a name="7.3" href="#7.3">7.3 Complex arithmetic <complex.h></a></h3>
+<h3><a name="7.3" href="#7.3">7.3 Complex arithmetic <complex.h></a></h3>
<h4><a name="7.3.1" href="#7.3.1">7.3.1 Introduction</a></h4>
<p><!--para 1 -->
<p><!--para 2 -->
The macro
<pre>
- complex</pre>
+ complex
+</pre>
expands to _Complex; the macro
<pre>
- _Complex_I</pre>
+ _Complex_I
+</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>
- imaginary</pre>
+ imaginary
+</pre>
and
<pre>
- _Imaginary_I</pre>
+ _Imaginary_I
+</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>
- I</pre>
+ I
+</pre>
expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not
defined, I shall expand to _Complex_I.
<p><!--para 5 -->
<!--page 183 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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 2 = -1.
+<p><small><a name="note167" href="#note167">167)</a> The imaginary unit is a number i such that i<sup>2</sup> = -1.
</small>
<p><small><a name="note168" href="#note168">168)</a> A specification for imaginary types is in informative <a href="#G">annex G</a>.
</small>
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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
- #pragma STDC CX_LIMITED_RANGE on-off-switch</pre>
-<h6>Description</h6>
+ #pragma STDC CX_LIMITED_RANGE on-off-switch
+</pre>
+<p><b>Description</b>
<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''.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note169" href="#note169">169)</a> The purpose of the pragma is to allow the implementation to use the formulas:
<pre>
(x + iy) x (u + iv) = (xu - yv) + i(yu + xv)
- (x + iy) / (u + iv) = [(xu + yv) + i(yu - xv)]/(u2 + v 2 )
- | x + iy | = (sqrt) x 2 + y 2
- ???????????????</pre>
+ (x + iy) / (u + iv) = [(xu + yv) + i(yu - xv)]/(u<sup>2</sup> + v<sup>2</sup>)
+ | x + iy | = (sqrt)(x<sup>2</sup> + y<sup>2</sup>)
+</pre>
where the programmer can determine they are safe.
</small>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacos(double complex z);
float complex cacosf(float complex z);
- long double complex cacosl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex cacosl(long double complex z);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casin(double complex z);
float complex casinf(float complex z);
- long double complex casinl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex casinl(long double complex z);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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]
<!--page 185 -->
<h5><a name="7.3.5.3" href="#7.3.5.3">7.3.5.3 The catan functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catan(double complex z);
float complex catanf(float complex z);
- long double complex catanl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex catanl(long double complex z);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccos(double complex z);
float complex ccosf(float complex z);
- long double complex ccosl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex ccosl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ccos functions compute the complex cosine of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csin(double complex z);
float complex csinf(float complex z);
- long double complex csinl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex csinl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The csin functions compute the complex sine of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctan(double complex z);
float complex ctanf(float complex z);
- long double complex ctanl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex ctanl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ctan functions compute the complex tangent of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacosh(double complex z);
float complex cacoshf(float complex z);
- long double complex cacoshl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex cacoshl(long double complex z);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casinh(double complex z);
float complex casinhf(float complex z);
- long double complex casinhl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex casinhl(long double complex z);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catanh(double complex z);
float complex catanhf(float complex z);
- long double complex catanhl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex catanhl(long double complex z);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccosh(double complex z);
float complex ccoshf(float complex z);
- long double complex ccoshl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex ccoshl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ccosh functions compute the complex hyperbolic cosine of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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);
- long double complex csinhl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex csinhl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The csinh functions compute the complex hyperbolic sine of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctanh(double complex z);
float complex ctanhf(float complex z);
- long double complex ctanhl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex ctanhl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ctanh functions compute the complex hyperbolic tangent of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cexp(double complex z);
float complex cexpf(float complex z);
- long double complex cexpl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex cexpl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The cexp functions compute the complex base-e exponential of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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);
- long double complex clogl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex clogl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The clog functions compute the complex natural (base-e) logarithm of z, with a branch
cut along the negative real axis.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cabs(double complex z);
float cabsf(float complex z);
- long double cabsl(long double complex z);</pre>
-<h6>Description</h6>
+ long double cabsl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The cabs functions compute the complex absolute value (also called norm, modulus, or
magnitude) of z.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- long double complex y);</pre>
-<h6>Description</h6>
+ long double complex y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csqrt(double complex z);
float complex csqrtf(float complex z);
- long double complex csqrtl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex csqrtl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The csqrt functions compute the complex square root of z, with a branch cut along the
negative real axis.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double carg(double complex z);
float cargf(float complex z);
- long double cargl(long double complex z);</pre>
-<h6>Description</h6>
+ long double cargl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The carg functions compute the argument (also called phase angle) of z, with a branch
cut along the negative real axis.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<!--page 191 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cimag(double complex z);
float cimagf(float complex z);
- long double cimagl(long double complex z);</pre>
-<h6>Description</h6>
+ long double cimagl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The cimag functions compute the imaginary part of z.<sup><a href="#note170"><b>170)</b></a></sup>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The cimag functions return the imaginary part value (as a real).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex conj(double complex z);
float complex conjf(float complex z);
- long double complex conjl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex conjl(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The conj functions compute the complex conjugate of z, by reversing the sign of its
imaginary part.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cproj(double complex z);
float complex cprojf(float complex z);
- long double complex cprojl(long double complex z);</pre>
-<h6>Description</h6>
+ long double complex cprojl(long double complex z);
+</pre>
+<p><b>Description</b>
<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>
- INFINITY + I * copysign(0.0, cimag(z))</pre>
-<h6>Returns</h6>
+ INFINITY + I * copysign(0.0, cimag(z))
+</pre>
+<p><b>Returns</b>
<p><!--para 3 -->
The cproj functions return the value of the projection onto the Riemann sphere.
<!--page 192 -->
<h5><a name="7.3.9.5" href="#7.3.9.5">7.3.9.5 The creal functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double creal(double complex z);
float crealf(float complex z);
- long double creall(long double complex z);</pre>
-<h6>Description</h6>
+ long double creall(long double complex z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The creal functions compute the real part of z.<sup><a href="#note171"><b>171)</b></a></sup>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The creal functions return the real part value.
<!--page 193 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note171" href="#note171">171)</a> For a variable z of complex type, z == creal(z) + cimag(z)*I.
</small>
-<h3><a name="7.4" href="#7.4">7.4 Character handling <ctype.h></a></h3>
+<h3><a name="7.4" href="#7.4">7.4 Character handling <ctype.h></a></h3>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isalnum(int c);</pre>
-<h6>Description</h6>
+ int isalnum(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isalpha(int c);</pre>
-<h6>Description</h6>
+ int isalpha(int c);
+</pre>
+<p><b>Description</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isblank(int c);</pre>
-<h6>Description</h6>
+ int isblank(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int iscntrl(int c);</pre>
-<h6>Description</h6>
+ int iscntrl(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isdigit(int c);</pre>
-<h6>Description</h6>
+ int isdigit(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isgraph(int c);</pre>
+ int isgraph(int c);
+</pre>
<!--page 195 -->
-<h6>Description</h6>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int islower(int c);</pre>
-<h6>Description</h6>
+ int islower(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isprint(int c);</pre>
-<h6>Description</h6>
+ int isprint(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int ispunct(int c);</pre>
-<h6>Description</h6>
+ int ispunct(int c);
+</pre>
+<p><b>Description</b>
<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"
nor isalnum is true.
<h5><a name="7.4.1.10" href="#7.4.1.10">7.4.1.10 The isspace function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isspace(int c);</pre>
-<h6>Description</h6>
+ int isspace(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isupper(int c);</pre>
-<h6>Description</h6>
+ int isupper(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int isxdigit(int c);</pre>
-<h6>Description</h6>
+ int isxdigit(int c);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int tolower(int c);</pre>
-<h6>Description</h6>
+ int tolower(int c);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The tolower function converts an uppercase letter to a corresponding lowercase letter.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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,
<!--page 197 -->
<h5><a name="7.4.2.2" href="#7.4.2.2">7.4.2.2 The toupper function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
- int toupper(int c);</pre>
-<h6>Description</h6>
+ int toupper(int c);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The toupper function converts a lowercase letter to a corresponding uppercase letter.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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,
for any given locale); otherwise, the argument is returned unchanged.
<!--page 198 -->
-<h3><a name="7.5" href="#7.5">7.5 Errors <errno.h></a></h3>
+<h3><a name="7.5" href="#7.5">7.5 Errors <errno.h></a></h3>
<p><!--para 1 -->
The header <a href="#7.5"><errno.h></a> defines several macros, all relating to the reporting of error
conditions.
<pre>
EDOM
EILSEQ
- ERANGE</pre>
+ ERANGE
+</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>
- errno</pre>
+ errno
+</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
<!--page 199 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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="note177" href="#note177">177)</a> See ''future library directions'' (<a href="#7.26.3">7.26.3</a>).
</small>
-<h3><a name="7.6" href="#7.6">7.6 Floating-point environment <fenv.h></a></h3>
+<h3><a name="7.6" href="#7.6">7.6 Floating-point environment <fenv.h></a></h3>
<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 3 -->
The type
<pre>
- fenv_t</pre>
+ fenv_t
+</pre>
represents the entire floating-point environment.
<p><!--para 4 -->
The type
<pre>
- fexcept_t</pre>
+ fexcept_t
+</pre>
represents the floating-point status flags collectively, including any status the
implementation associates with the flags.
FE_INEXACT
FE_INVALID
FE_OVERFLOW
- FE_UNDERFLOW</pre>
+ FE_UNDERFLOW
+</pre>
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
<p><!--para 6 -->
The macro
<pre>
- FE_ALL_EXCEPT</pre>
+ FE_ALL_EXCEPT
+</pre>
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 -->
FE_DOWNWARD
FE_TONEAREST
FE_TOWARDZERO
- FE_UPWARD</pre>
+ FE_UPWARD
+</pre>
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
<!--page 201 -->
<pre>
- FE_DFL_ENV</pre>
+ FE_DFL_ENV
+</pre>
represents the default floating-point environment -- the one installed at program startup
-<ul>
-<li> and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to
-</ul>
+ -- 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.
<p><!--para 9 -->
Additional implementation-defined environments, with macro definitions beginning with
FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may
also be specified by the implementation.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
</small>
<h4><a name="7.6.1" href="#7.6.1">7.6.1 The FENV_ACCESS pragma</a></h4>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- #pragma STDC FENV_ACCESS on-off-switch</pre>
-<h6>Description</h6>
+ #pragma STDC FENV_ACCESS on-off-switch
+</pre>
+<p><b>Description</b>
<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
<!--page 202 -->
<p><!--para 3 -->
EXAMPLE
-<p><!--para 4 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
void f(double x)
g(x + 1);
h(x + 1);
/* ... */
- }</pre>
+ }
+</pre>
+<p><!--para 4 -->
If the function g might depend on status flags set as a side effect of the first x + 1, or if the second
x + 1 might depend on control modes set as a side effect of the call to function g, then the program shall
contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.<sup><a href="#note185"><b>185)</b></a></sup>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
FE_OVERFLOW | FE_INEXACT. For other argument values the behavior of these
functions is undefined.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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-
</small>
<h5><a name="7.6.2.1" href="#7.6.2.1">7.6.2.1 The feclearexcept function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int feclearexcept(int excepts);</pre>
-<h6>Description</h6>
+ int feclearexcept(int excepts);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The feclearexcept function attempts to clear the supported floating-point exceptions
represented by its argument.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
<!--page 203 -->
<h5><a name="7.6.2.2" href="#7.6.2.2">7.6.2.2 The fegetexceptflag function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetexceptflag(fexcept_t *flagp,
- int excepts);</pre>
-<h6>Description</h6>
+ int excepts);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int feraiseexcept(int excepts);</pre>
-<h6>Description</h6>
+ int feraiseexcept(int excepts);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
<!--page 204 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetexceptflag(const fexcept_t *flagp,
- int excepts);</pre>
-<h6>Description</h6>
+ int excepts);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int fetestexcept(int excepts);</pre>
-<h6>Description</h6>
+ int fetestexcept(int excepts);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
if (set_excepts & FE_INVALID) f();
if (set_excepts & FE_OVERFLOW) g();
/* ... */
- }</pre>
+ }
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note188" href="#note188">188)</a> This mechanism allows testing several floating-point exceptions with just one function call.
</small>
modes.
<h5><a name="7.6.3.1" href="#7.6.3.1">7.6.3.1 The fegetround function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int fegetround(void);</pre>
-<h6>Description</h6>
+ int fegetround(void);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The fegetround function gets the current rounding direction.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int fesetround(int round);</pre>
-<h6>Description</h6>
+ int fesetround(int round);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The fesetround function returns zero if and only if the requested rounding direction
was established.
/* ... */
fesetround(save_round);
/* ... */
- }</pre>
+ }
+</pre>
<h4><a name="7.6.4" href="#7.6.4">7.6.4 Environment</a></h4>
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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int fegetenv(fenv_t *envp);</pre>
-<h6>Description</h6>
+ int fegetenv(fenv_t *envp);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The fegetenv function attempts to store the current floating-point environment in the
object pointed to by envp.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int feholdexcept(fenv_t *envp);</pre>
-<h6>Description</h6>
+ int feholdexcept(fenv_t *envp);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The feholdexcept function returns zero if and only if non-stop floating-point
exception handling was successfully installed.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="7.6.4.3" href="#7.6.4.3">7.6.4.3 The fesetenv function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int fesetenv(const fenv_t *envp);</pre>
-<h6>Description</h6>
+ int fesetenv(const fenv_t *envp);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
- int feupdateenv(const fenv_t *envp);</pre>
-<h6>Description</h6>
+ int feupdateenv(const fenv_t *envp);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The feupdateenv function returns zero if all the actions were successfully carried out.
Otherwise, it returns a nonzero value.
if (feupdateenv(&save_env))
return /* indication of an environmental problem */;
return result;
- }</pre>
+ }
+</pre>
-<h3><a name="7.7" href="#7.7">7.7 Characteristics of floating types <float.h></a></h3>
+<h3><a name="7.7" href="#7.7">7.7 Characteristics of floating types <float.h></a></h3>
<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.
in <a href="#5.2.4.2.2">5.2.4.2.2</a>.
<!--page 210 -->
-<h3><a name="7.8" href="#7.8">7.8 Format conversion of integer types <inttypes.h></a></h3>
+<h3><a name="7.8" href="#7.8">7.8 Format conversion of integer types <inttypes.h></a></h3>
<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>
- imaxdiv_t</pre>
+ imaxdiv_t
+</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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note190" href="#note190">190)</a> See ''future library directions'' (<a href="#7.26.4">7.26.4</a>).
</small>
The fprintf macros for signed integers are:
<pre>
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
- PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR</pre>
+ PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR
+</pre>
<!--page 211 -->
<p><!--para 3 -->
The fprintf macros for unsigned integers are:
-<p><!--para 4 -->
<pre>
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR
- PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR</pre>
+ PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR
+</pre>
+<p><!--para 4 -->
The fscanf macros for signed integers are:
-<p><!--para 5 -->
<pre>
SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR
- SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR</pre>
+ SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR
+</pre>
+<p><!--para 5 -->
The fscanf macros for unsigned integers are:
-<p><!--para 6 -->
<pre>
SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR
SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR
- SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR</pre>
+ SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR
+</pre>
+<p><!--para 6 -->
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
wprintf(L"The largest integer value is %020"
PRIxMAX "\n", i);
return 0;
- }</pre>
+ }
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
- intmax_t imaxabs(intmax_t j);</pre>
-<h6>Description</h6>
+ intmax_t imaxabs(intmax_t j);
+</pre>
+<p><b>Description</b>
<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>
<!--page 212 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The imaxabs function returns the absolute value.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
- imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);</pre>
-<h6>Description</h6>
+ imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The imaxdiv function computes numer / denom and numer % denom in a single
operation.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- char ** restrict endptr, int base);</pre>
-<h6>Description</h6>
+ char ** restrict endptr, int base);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 213 -->
<h5><a name="7.8.2.4" href="#7.8.2.4">7.8.2.4 The wcstoimax and wcstoumax functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stddef.h></a> // for wchar_t
intmax_t wcstoimax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
uintmax_t wcstoumax(const wchar_t * restrict nptr,
- wchar_t ** restrict endptr, int base);</pre>
-<h6>Description</h6>
+ wchar_t ** restrict endptr, int base);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
(<a href="#7.24.4.1.2">7.24.4.1.2</a>).
<!--page 214 -->
-<h3><a name="7.9" href="#7.9">7.9 Alternative spellings <iso646.h></a></h3>
+<h3><a name="7.9" href="#7.9">7.9 Alternative spellings <iso646.h></a></h3>
<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):
or ||
or_eq |=
xor ^
- xor_eq ^=</pre>
+ xor_eq ^=
+</pre>
-<h3><a name="7.10" href="#7.10">7.10 Sizes of integer types <limits.h></a></h3>
+<h3><a name="7.10" href="#7.10">7.10 Sizes of integer types <limits.h></a></h3>
<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.
in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
<!--page 216 -->
-<h3><a name="7.11" href="#7.11">7.11 Localization <locale.h></a></h3>
+<h3><a name="7.11" href="#7.11">7.11 Localization <locale.h></a></h3>
<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>
- struct lconv</pre>
+ struct lconv
+</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 -->
-<p><!--para 3 -->
<pre>
char *decimal_point; // "."
char *thousands_sep; // ""
char int_p_sep_by_space; // CHAR_MAX
char int_n_sep_by_space; // CHAR_MAX
char int_p_sign_posn; // CHAR_MAX
- char int_n_sign_posn; // CHAR_MAX</pre>
+ char int_n_sign_posn; // CHAR_MAX
+</pre>
+<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>); and
<pre>
LC_ALL
LC_CTYPE
LC_MONETARY
LC_NUMERIC
- LC_TIME</pre>
+ LC_TIME
+</pre>
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.11"><locale.h></a>
- char *setlocale(int category, const char *locale);</pre>
-<h6>Description</h6>
+ char *setlocale(int category, const char *locale);
+</pre>
+<p><b>Description</b>
<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 4 -->
At program startup, the equivalent of
<pre>
- setlocale(LC_ALL, "C");</pre>
+ setlocale(LC_ALL, "C");
+</pre>
is executed.
<p><!--para 5 -->
The implementation shall behave as if no library function calls the setlocale function.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note196" href="#note196">196)</a> The only functions in <a href="#7.4">7.4</a> whose behavior is not affected by the current locale are isdigit and
isxdigit.
</small>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.11"><locale.h></a>
- struct lconv *localeconv(void);</pre>
-<h6>Description</h6>
+ struct lconv *localeconv(void);
+</pre>
+<p><b>Description</b>
<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)
strings shall start and end in the initial shift state. The members with type char are
nonnegative numbers, any of which can be CHAR_MAX to indicate that the value is not
available in the current locale. The members include the following:
- char *decimal_point
-<pre>
- The decimal-point character used to format nonmonetary quantities.</pre>
- char *thousands_sep
-<pre>
+<dl>
+<dt> char *decimal_point
+<dd>
+ The decimal-point character used to format nonmonetary quantities.
+<dt> char *thousands_sep
+<dd>
The character used to separate groups of digits before the decimal-point
- character in formatted nonmonetary quantities.</pre>
- char *grouping
-<pre>
+ character in formatted nonmonetary quantities.
+<dt> char *grouping
+<dd>
A string whose elements indicate the size of each group of digits in
- formatted nonmonetary quantities.</pre>
- char *mon_decimal_point
-<pre>
- The decimal-point used to format monetary quantities.</pre>
- char *mon_thousands_sep
-<pre>
+ formatted nonmonetary quantities.
+<dt> char *mon_decimal_point
+<dd>
+ The decimal-point used to format monetary quantities.
+<dt> char *mon_thousands_sep
+<dd>
The separator for groups of digits before the decimal-point in formatted
- monetary quantities.</pre>
- char *mon_grouping
-<pre>
+ monetary quantities.
+<dt> char *mon_grouping
+<dd>
A string whose elements indicate the size of each group of digits in
- formatted monetary quantities.</pre>
- char *positive_sign
-<pre>
+ formatted monetary quantities.
+<dt> char *positive_sign
+<dd>
The string used to indicate a nonnegative-valued formatted monetary
- quantity.</pre>
- char *negative_sign
-<pre>
- The string used to indicate a negative-valued formatted monetary quantity.</pre>
- char *currency_symbol
-<pre>
- The local currency symbol applicable to the current locale.</pre>
- char frac_digits
-<pre>
+ quantity.
+<dt> char *negative_sign
+<dd>
+ The string used to indicate a negative-valued formatted monetary quantity.
+<dt> char *currency_symbol
+<dd>
+ The local currency symbol applicable to the current locale.
+<dt> char frac_digits
+<dd>
The number of fractional digits (those after the decimal-point) to be
- displayed in a locally formatted monetary quantity.</pre>
- char p_cs_precedes
-<pre>
+ displayed in a locally formatted monetary quantity.
+<dt> char p_cs_precedes
+<dd>
Set to 1 or 0 if the currency_symbol respectively precedes or
- succeeds the value for a nonnegative locally formatted monetary quantity.</pre>
- char n_cs_precedes
+ succeeds the value for a nonnegative locally formatted monetary quantity.
+<dt> char n_cs_precedes
<!--page 220 -->
-<pre>
+<dd>
Set to 1 or 0 if the currency_symbol respectively precedes or
- succeeds the value for a negative locally formatted monetary quantity.</pre>
- char p_sep_by_space
-<pre>
+ succeeds the value for a negative locally formatted monetary quantity.
+<dt> char p_sep_by_space
+<dd>
Set to a value indicating the separation of the currency_symbol, the
sign string, and the value for a nonnegative locally formatted monetary
- quantity.</pre>
- char n_sep_by_space
-<pre>
+ quantity.
+<dt> char n_sep_by_space
+<dd>
Set to a value indicating the separation of the currency_symbol, the
sign string, and the value for a negative locally formatted monetary
- quantity.</pre>
- char p_sign_posn
-<pre>
+ quantity.
+<dt> char p_sign_posn
+<dd>
Set to a value indicating the positioning of the positive_sign for a
- nonnegative locally formatted monetary quantity.</pre>
- char n_sign_posn
-<pre>
+ nonnegative locally formatted monetary quantity.
+<dt> char n_sign_posn
+<dd>
Set to a value indicating the positioning of the negative_sign for a
- negative locally formatted monetary quantity.</pre>
- char *int_curr_symbol
-<pre>
+ negative locally formatted monetary quantity.
+<dt> char *int_curr_symbol
+<dd>
The international currency symbol applicable to the current locale. The
first three characters contain the alphabetic international currency symbol
in accordance with those specified in ISO 4217. The fourth character
(immediately preceding the null character) is the character used to separate
- the international currency symbol from the monetary quantity.</pre>
- char int_frac_digits
-<pre>
+ the international currency symbol from the monetary quantity.
+<dt> char int_frac_digits
+<dd>
The number of fractional digits (those after the decimal-point) to be
- displayed in an internationally formatted monetary quantity.</pre>
- char int_p_cs_precedes
-<pre>
+ displayed in an internationally formatted monetary quantity.
+<dt> char int_p_cs_precedes
+<dd>
Set to 1 or 0 if the int_curr_symbol respectively precedes or
succeeds the value for a nonnegative internationally formatted monetary
- quantity.</pre>
- char int_n_cs_precedes
-<pre>
+ quantity.
+<dt> char int_n_cs_precedes
+<dd>
Set to 1 or 0 if the int_curr_symbol respectively precedes or
succeeds the value for a negative internationally formatted monetary
- quantity.</pre>
- char int_p_sep_by_space
+ quantity.
+<dt> char int_p_sep_by_space
<!--page 221 -->
-<pre>
+<dd>
Set to a value indicating the separation of the int_curr_symbol, the
sign string, and the value for a nonnegative internationally formatted
- monetary quantity.</pre>
- char int_n_sep_by_space
-<pre>
+ monetary quantity.
+<dt> char int_n_sep_by_space
+<dd>
Set to a value indicating the separation of the int_curr_symbol, the
sign string, and the value for a negative internationally formatted monetary
- quantity.</pre>
- char int_p_sign_posn
-<pre>
+ quantity.
+<dt> char int_p_sign_posn
+<dd>
Set to a value indicating the positioning of the positive_sign for a
- nonnegative internationally formatted monetary quantity.</pre>
- char int_n_sign_posn
-<p><!--para 4 -->
-<pre>
+ nonnegative internationally formatted monetary quantity.
+<dt> char int_n_sign_posn
+<dd>
Set to a value indicating the positioning of the negative_sign for a
- negative internationally formatted monetary quantity.</pre>
+ negative internationally formatted monetary quantity.
+</dl>
+<p><!--para 4 -->
The elements of grouping and mon_grouping are interpreted according to the
following:
- CHAR_MAX No further grouping is to be performed.
- 0 The previous element is to be repeatedly used for the remainder of the
-<pre>
- digits.</pre>
- other The integer value is the number of digits that compose the current group.
-<p><!--para 5 -->
-<pre>
+<dl>
+<dt> CHAR_MAX <dd>No further grouping is to be performed.
+<dt> 0 <dd>The previous element is to be repeatedly used for the remainder of the
+ digits.
+<dt> other <dd>The integer value is the number of digits that compose the current group.
The next element is examined to determine the size of the next group of
- digits before the current group.</pre>
+ digits before the current group.
+</dl>
+<p><!--para 5 -->
The values of p_sep_by_space, n_sep_by_space, int_p_sep_by_space,
and int_n_sep_by_space are interpreted according to the following:
- 0 No space separates the currency symbol and value.
- 1 If the currency symbol and sign string are adjacent, a space separates them from the
-<pre>
- value; otherwise, a space separates the currency symbol from the value.</pre>
- 2 If the currency symbol and sign string are adjacent, a space separates them;
-<pre>
- otherwise, a space separates the sign string from the value.</pre>
+<dl>
+<dt> 0 <dd>No space separates the currency symbol and value.
+<dt> 1 <dd>If the currency symbol and sign string are adjacent, a space separates them from the
+ value; otherwise, a space separates the currency symbol from the value.
+<dt> 2 <dd>If the currency symbol and sign string are adjacent, a space separates them;
+ otherwise, a space separates the sign string from the value.
+</dl>
For int_p_sep_by_space and int_n_sep_by_space, the fourth character of
int_curr_symbol is used instead of a space.
<p><!--para 6 -->
The values of p_sign_posn, n_sign_posn, int_p_sign_posn, and
int_n_sign_posn are interpreted according to the following:
- 0 Parentheses surround the quantity and currency symbol.
- 1 The sign string precedes the quantity and currency symbol.
- 2 The sign string succeeds the quantity and currency symbol.
- 3 The sign string immediately precedes the currency symbol.
- 4 The sign string immediately succeeds the currency symbol.
+<dl>
+<dt> 0 <dd>Parentheses surround the quantity and currency symbol.
+<dt> 1 <dd>The sign string precedes the quantity and currency symbol.
+<dt> 2 <dd>The sign string succeeds the quantity and currency symbol.
+<dt> 3 <dd>The sign string immediately precedes the currency symbol.
+<dt> 4 <dd>The sign string immediately succeeds the currency symbol.
+</dl>
<!--page 222 -->
<p><!--para 7 -->
The implementation shall behave as if no library function calls the localeconv
function.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
EXAMPLE 1 The following table illustrates rules which may well be used by four countries to format
monetary quantities.
<pre>
- Local format International format</pre>
+ Local format International format
- Country Positive Negative Positive Negative
+ Country Positive Negative Positive Negative
Country1 1.234,56 mk -1.234,56 mk FIM 1.234,56 FIM -1.234,56
Country2 L.1.234 -L.1.234 ITL 1.234 -ITL 1.234
- Country3 fl. 1.234,56 fl. -1.234,56 NLG 1.234,56 NLG -1.234,56
+ Country3 fl. 1.234,56 fl. -1.234,56 NLG 1.234,56 NLG -1.234,56
Country4 SFrs.1,234.56 SFrs.1,234.56C CHF 1,234.56 CHF 1,234.56C
+</pre>
<p><!--para 10 -->
For these four countries, the respective values for the monetary members of the structure returned by
localeconv could be:
<pre>
- Country1 Country2 Country3 Country4</pre>
+ Country1 Country2 Country3 Country4
mon_decimal_point "," "" "," "."
mon_thousands_sep "." "." "." ","
int_n_sep_by_space 2 1 2 1
int_p_sign_posn 1 1 1 1
int_n_sign_posn 4 1 4 2
+</pre>
<!--page 223 -->
<p><!--para 11 -->
EXAMPLE 2 The following table illustrates how the cs_precedes, sep_by_space, and sign_posn members
affect the formatted value.
<pre>
- p_sep_by_space</pre>
-
- p_cs_precedes p_sign_posn 0 1 2
-
-<pre>
- 0 0 (<a href="#1.25">1.25</a>$) (<a href="#1.25">1.25</a> $) (<a href="#1.25">1.25</a>$)
- 1 +1.25$ +1.25 $ + <a href="#1.25">1.25</a>$
- 2 <a href="#1.25">1.25</a>$+ <a href="#1.25">1.25</a> $+ <a href="#1.25">1.25</a>$ +
- 3 <a href="#1.25">1.25</a>+$ <a href="#1.25">1.25</a> +$ <a href="#1.25">1.25</a>+ $
- 4 <a href="#1.25">1.25</a>$+ <a href="#1.25">1.25</a> $+ <a href="#1.25">1.25</a>$ +</pre>
-
-<!--page 224 -->
-<pre>
- 1 0 ($1.25) ($ <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
- 4 $+1.25 $+ <a href="#1.25">1.25</a> $ +1.25</pre>
+ p_sep_by_space
+ p_cs_precedes p_sign_posn 0 1 2
+
+ 0 0 (<a href="#1.25">1.25</a>$) (<a href="#1.25">1.25</a> $) (<a href="#1.25">1.25</a>$)
+ 1 +1.25$ +1.25 $ + <a href="#1.25">1.25</a>$
+ 2 <a href="#1.25">1.25</a>$+ <a href="#1.25">1.25</a> $+ <a href="#1.25">1.25</a>$ +
+ 3 <a href="#1.25">1.25</a>+$ <a href="#1.25">1.25</a> +$ <a href="#1.25">1.25</a>+ $
+ 4 <a href="#1.25">1.25</a>$+ <a href="#1.25">1.25</a> $+ <a href="#1.25">1.25</a>$ +
+
+ 1 0 ($1.25) ($ <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
+ 4 $+1.25 $+ <a href="#1.25">1.25</a> $ +1.25
+</pre>
-<h3><a name="7.12" href="#7.12">7.12 Mathematics <math.h></a></h3>
+<!--page 224 -->
+<h3><a name="7.12" href="#7.12">7.12 Mathematics <math.h></a></h3>
<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
The types
<pre>
float_t
- double_t</pre>
+ double_t
+</pre>
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
<p><!--para 3 -->
The macro
<pre>
- HUGE_VAL</pre>
+ HUGE_VAL
+</pre>
expands to a positive double constant expression, not necessarily representable as a
float. The macros
<pre>
HUGE_VALF
- HUGE_VALL</pre>
+ HUGE_VALL
+</pre>
are respectively float and long double analogs of HUGE_VAL.<sup><a href="#note200"><b>200)</b></a></sup>
<p><!--para 4 -->
The macro
<pre>
- INFINITY</pre>
+ INFINITY
+</pre>
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
<p><!--para 5 -->
The macro
<pre>
- NAN</pre>
+ NAN
+</pre>
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 -->
FP_NAN
FP_NORMAL
FP_SUBNORMAL
- FP_ZERO</pre>
+ FP_ZERO
+</pre>
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,
<p><!--para 7 -->
The macro
<pre>
- FP_FAST_FMA</pre>
+ FP_FAST_FMA
+</pre>
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
- FP_FAST_FMAL</pre>
+ FP_FAST_FMAL
+</pre>
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
- FP_ILOGBNAN</pre>
+ FP_ILOGBNAN
+</pre>
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.
The macros
<pre>
MATH_ERRNO
- MATH_ERREXCEPT</pre>
+ MATH_ERREXCEPT
+</pre>
expand to the integer constants 1 and 2, respectively; the macro
<pre>
- math_errhandling</pre>
+ math_errhandling
+</pre>
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>.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
</small>
<h4><a name="7.12.2" href="#7.12.2">7.12.2 The FP_CONTRACT pragma</a></h4>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- #pragma STDC FP_CONTRACT on-off-switch</pre>
-<h6>Description</h6>
+ #pragma STDC FP_CONTRACT on-off-switch
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int fpclassify(real-floating x);</pre>
-<h6>Description</h6>
+ int fpclassify(real-floating x);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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) : \
- __fpclassifyl(x))</pre>
+ __fpclassifyl(x))
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isfinite(real-floating x);</pre>
-<h6>Description</h6>
+ int isfinite(real-floating x);
+</pre>
+<p><b>Description</b>
<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
<!--page 229 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isinf(real-floating x);</pre>
-<h6>Description</h6>
+ int isinf(real-floating x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isnan(real-floating x);</pre>
-<h6>Description</h6>
+ int isnan(real-floating x);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The isnan macro returns a nonzero value if and only if its argument has a NaN value.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isnormal(real-floating x);</pre>
+ int isnormal(real-floating x);
+</pre>
<!--page 230 -->
-<h6>Description</h6>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int signbit(real-floating x);</pre>
-<h6>Description</h6>
+ int signbit(real-floating x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The signbit macro determines whether the sign of its argument value is negative.<sup><a href="#note207"><b>207)</b></a></sup>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The signbit macro returns a nonzero value if and only if the sign of its argument value
is negative.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double acos(double x);
float acosf(float x);
- long double acosl(long double x);</pre>
-<h6>Description</h6>
+ long double acosl(long double x);
+</pre>
+<p><b>Description</b>
<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].
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The acos functions return arccos x in the interval [0, pi ] radians.
<!--page 231 -->
<h5><a name="7.12.4.2" href="#7.12.4.2">7.12.4.2 The asin functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double asin(double x);
float asinf(float x);
- long double asinl(long double x);</pre>
-<h6>Description</h6>
+ long double asinl(long double x);
+</pre>
+<p><b>Description</b>
<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].
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan(double x);
float atanf(float x);
- long double atanl(long double x);</pre>
-<h6>Description</h6>
+ long double atanl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The atan functions compute the principal value of the arc tangent of x.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan2(double y, double x);
float atan2f(float y, float x);
- long double atan2l(long double y, long double x);</pre>
-<h6>Description</h6>
+ long double atan2l(long double y, long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cos(double x);
float cosf(float x);
- long double cosl(long double x);</pre>
-<h6>Description</h6>
+ long double cosl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The cos functions compute the cosine of x (measured in radians).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sin(double x);
float sinf(float x);
- long double sinl(long double x);</pre>
-<h6>Description</h6>
+ long double sinl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The sin functions compute the sine of x (measured in radians).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tan(double x);
float tanf(float x);
- long double tanl(long double x);</pre>
-<h6>Description</h6>
+ long double tanl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The tan functions return the tangent of x (measured in radians).
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The tan functions return tan x.
<!--page 233 -->
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double acosh(double x);
float acoshf(float x);
- long double acoshl(long double x);</pre>
-<h6>Description</h6>
+ long double acoshl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
error occurs for arguments less than 1.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double asinh(double x);
float asinhf(float x);
- long double asinhl(long double x);</pre>
-<h6>Description</h6>
+ long double asinhl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The asinh functions compute the arc hyperbolic sine of x.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atanh(double x);
float atanhf(float x);
- long double atanhl(long double x);</pre>
-<h6>Description</h6>
+ long double atanhl(long double x);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cosh(double x);
float coshf(float x);
- long double coshl(long double x);</pre>
-<h6>Description</h6>
+ long double coshl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
magnitude of x is too large.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sinh(double x);
float sinhf(float x);
- long double sinhl(long double x);</pre>
-<h6>Description</h6>
+ long double sinhl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The sinh functions compute the hyperbolic sine of x. A range error occurs if the
magnitude of x is too large.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tanh(double x);
float tanhf(float x);
- long double tanhl(long double x);</pre>
-<h6>Description</h6>
+ long double tanhl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The tanh functions compute the hyperbolic tangent of x.
<!--page 235 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double exp(double x);
float expf(float x);
- long double expl(long double x);</pre>
-<h6>Description</h6>
+ long double expl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The exp functions return ex .
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double exp2(double x);
float exp2f(float x);
- long double exp2l(long double x);</pre>
-<h6>Description</h6>
+ long double exp2l(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The exp2 functions return 2x .
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<!--page 236 -->
<pre>
#include <a href="#7.12"><math.h></a>
double expm1(double x);
float expm1f(float x);
- long double expm1l(long double x);</pre>
-<h6>Description</h6>
+ long double expm1l(long double x);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The expm1 functions return ex - 1.
+ The expm1 functions return e<sup>x</sup> - 1.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double frexp(double value, int *exp);
float frexpf(float value, int *exp);
- long double frexpl(long double value, int *exp);</pre>
-<h6>Description</h6>
+ long double frexpl(long double value, int *exp);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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 x 2*exp . If value is zero, both parts of the result are zero.
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int ilogb(double x);
int ilogbf(float x);
- int ilogbl(long double x);</pre>
-<h6>Description</h6>
+ int ilogbl(long double x);
+</pre>
+<p><b>Description</b>
<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
<!--page 237 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
- long double ldexpl(long double x, int exp);</pre>
-<h6>Description</h6>
+ long double ldexpl(long double x, int exp);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ldexp functions multiply a floating-point number by an integral power of 2. A
range error may occur.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The ldexp functions return x x 2exp .
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log(double x);
float logf(float x);
- long double logl(long double x);</pre>
-<h6>Description</h6>
+ long double logl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<!--page 238 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log10(double x);
float log10f(float x);
- long double log10l(long double x);</pre>
-<h6>Description</h6>
+ long double log10l(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log1p(double x);
float log1pf(float x);
- long double log1pl(long double x);</pre>
-<h6>Description</h6>
+ long double log1pl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The log1p functions return loge (1 + x).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log2(double x);
float log2f(float x);
- long double log2l(long double x);</pre>
-<h6>Description</h6>
+ long double log2l(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The log2 functions return log2 x.
<!--page 239 -->
<h5><a name="7.12.6.11" href="#7.12.6.11">7.12.6.11 The logb functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double logb(double x);
float logbf(float x);
- long double logbl(long double x);</pre>
-<h6>Description</h6>
+ long double logbl(long double x);
+</pre>
+<p><b>Description</b>
<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>
- 1 <= x x FLT_RADIX-logb(x) < FLT_RADIX</pre>
+ 1 <= x FLT_RADIX<sup>-logb(x)</sup> < FLT_RADIX
+</pre>
A domain error or range error may occur if the argument is zero.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double modf(double value, double *iptr);
float modff(float value, float *iptr);
- long double modfl(long double value, long double *iptr);</pre>
-<h6>Description</h6>
+ long double modfl(long double value, long double *iptr);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long double scalbnl(long double x, int n);
double scalbln(double x, long int n);
float scalblnf(float x, long int n);
- long double scalblnl(long double x, long int n);</pre>
-<h6>Description</h6>
+ long double scalblnl(long double x, long int n);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
- The scalbn and scalbln functions compute x x FLT_RADIXn efficiently, not
- normally by computing FLT_RADIXn explicitly. A range error may occur.
-<h6>Returns</h6>
+ 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><b>Returns</b>
<p><!--para 3 -->
- The scalbn and scalbln functions return x x FLT_RADIXn .
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cbrt(double x);
float cbrtf(float x);
- long double cbrtl(long double x);</pre>
-<h6>Description</h6>
+ long double cbrtl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The cbrt functions compute the real cube root of x.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The cbrt functions return x1/3 .
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fabs(double x);
float fabsf(float x);
- long double fabsl(long double x);</pre>
-<h6>Description</h6>
+ long double fabsl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The fabs functions compute the absolute value of a floating-point number x.
<!--page 241 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double hypot(double x, double y);
float hypotf(float x, float y);
- long double hypotl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double hypotl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 4 -->
- The hypot functions return (sqrt)x2 + y2 .
-<pre>
- ???
- ???????????????</pre>
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double pow(double x, double y);
float powf(float x, float y);
- long double powl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double powl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The pow functions return xy .
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<!--page 242 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sqrt(double x);
float sqrtf(float x);
- long double sqrtl(long double x);</pre>
-<h6>Description</h6>
+ long double sqrtl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The sqrt functions compute the nonnegative square root of x. A domain error occurs if
the argument is less than zero.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The sqrt functions return (sqrt)x.
-<pre>
- ???
- ???</pre>
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double erf(double x);
float erff(float x);
- long double erfl(long double x);</pre>
-<h6>Description</h6>
+ long double erfl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The erf functions compute the error function of x.
-<h6>Returns</h6>
-<pre>
- 2 x
- (integral)</pre>
-
- The erf functions return erf x = e-t dt.
-<pre>
- 2</pre>
-
-
+<p><b>Returns</b>
+<p><!--para 3 -->
+ The erf functions return
<pre>
- (sqrt)pi
- ???
- ??? 0</pre>
-
+ 2 x
+ erf x = --- (integral) e<sup>-t<sup>2</sup></sup> dt .
+ (sqrt)(pi) 0
+</pre>
<h5><a name="7.12.8.2" href="#7.12.8.2">7.12.8.2 The erfc functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double erfc(double x);
float erfcf(float x);
- long double erfcl(long double x);</pre>
-<h6>Description</h6>
+ long double erfcl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The erfc functions compute the complementary error function of x. A range error
occurs if x is too large.
-<h6>Returns</h6>
-<pre>
- 2 (inf)
- (integral)</pre>
-
- The erfc functions return erfc x = 1 - erf x = e-t dt.
+<p><b>Returns</b>
+<p><!--para 3 -->
+ The erfc functions return
<pre>
- 2</pre>
-
+ 2 (inf)
+ erfc x = 1 - erf x = --- (integral) e<sup>-t<sup>2</sup></sup> dt .
+ (sqrt)(pi) x
+</pre>
<!--page 243 -->
-<pre>
- (sqrt)pi
- ???
- ??? x</pre>
-
<h5><a name="7.12.8.3" href="#7.12.8.3">7.12.8.3 The lgamma functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double lgamma(double x);
float lgammaf(float x);
- long double lgammal(long double x);</pre>
-<h6>Description</h6>
+ long double lgammal(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tgamma(double x);
float tgammaf(float x);
- long double tgammal(long double x);</pre>
-<h6>Description</h6>
+ long double tgammal(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ceil(double x);
float ceilf(float x);
- long double ceill(long double x);</pre>
-<h6>Description</h6>
+ long double ceill(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ceil functions compute the smallest integer value not less than x.
<!--page 244 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The ceil functions return ???x???, expressed as a floating-point number.
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double floor(double x);
float floorf(float x);
- long double floorl(long double x);</pre>
-<h6>Description</h6>
+ long double floorl(long double x);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The floor functions compute the largest integer value not greater than x.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The floor functions return ???x???, expressed as a floating-point number.
+ 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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nearbyint(double x);
float nearbyintf(float x);
- long double nearbyintl(long double x);</pre>
-<h6>Description</h6>
+ long double nearbyintl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double rint(double x);
float rintf(float x);
- long double rintl(long double x);</pre>
-<h6>Description</h6>
+ long double rintl(long double x);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long int lrintl(long double x);
long long int llrint(double x);
long long int llrintf(float x);
- long long int llrintl(long double x);</pre>
-<h6>Description</h6>
+ long long int llrintl(long double x);
+</pre>
+<p><b>Description</b>
<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. *
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double round(double x);
float roundf(float x);
- long double roundl(long double x);</pre>
-<h6>Description</h6>
+ long double roundl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long int lroundl(long double x);
long long int llround(double x);
long long int llroundf(float x);
- long long int llroundl(long double x);</pre>
-<h6>Description</h6>
+ long long int llroundl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double trunc(double x);
float truncf(float x);
- long double truncl(long double x);</pre>
-<h6>Description</h6>
+ long double truncl(long double x);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The trunc functions return the truncated integer value.
<!--page 247 -->
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmod(double x, double y);
float fmodf(float x, float y);
- long double fmodl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double fmodl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The fmod functions compute the floating-point remainder of x/y.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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,
defined.
<h5><a name="7.12.10.2" href="#7.12.10.2">7.12.10.2 The remainder functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remainder(double x, double y);
float remainderf(float x, float y);
- long double remainderl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double remainderl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The remainder functions compute the remainder x REM y required by IEC 60559.<sup><a href="#note210"><b>210)</b></a></sup>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
<!--page 248 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="7.12.10.3" href="#7.12.10.3">7.12.10.3 The remquo functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- int *quo);</pre>
-<h6>Description</h6>
+ int *quo);
+</pre>
+<p><b>Description</b>
<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 2n to the magnitude of the integral quotient of x/y, where
+ 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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double copysign(double x, double y);
float copysignf(float x, float y);
- long double copysignl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double copysignl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nan(const char *tagp);
float nanf(const char *tagp);
- long double nanl(const char *tagp);</pre>
-<h6>Description</h6>
+ long double nanl(const char *tagp);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nextafter(double x, double y);
float nextafterf(float x, float y);
- long double nextafterl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double nextafterl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The nextafter functions return the next representable value in the specified format
after x in the direction of y.
<!--page 250 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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);
- long double nexttowardl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double nexttowardl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fdim(double x, double y);
float fdimf(float x, float y);
- long double fdiml(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double fdiml(long double x, long double y);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The fdim functions determine the positive difference between their arguments:
<pre>
- ???x - y if x > y
- ???
- ???+0 if x <= y</pre>
+ {x - y if x > y
+ {
+ {+0 if x <= y
+</pre>
A range error may occur.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmax(double x, double y);
float fmaxf(float x, float y);
- long double fmaxl(long double x, long double y);</pre>
+ long double fmaxl(long double x, long double y);
+</pre>
<!--page 251 -->
-<h6>Description</h6>
+<p><b>Description</b>
<p><!--para 2 -->
The fmax functions determine the maximum numeric value of their arguments.<sup><a href="#note213"><b>213)</b></a></sup>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The fmax functions return the maximum numeric value of their arguments.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmin(double x, double y);
float fminf(float x, float y);
- long double fminl(long double x, long double y);</pre>
-<h6>Description</h6>
+ long double fminl(long double x, long double y);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The fmin functions determine the minimum numeric value of their arguments.<sup><a href="#note214"><b>214)</b></a></sup>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The fmin functions return the minimum numeric value of their arguments.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- long double z);</pre>
-<h6>Description</h6>
+ long double z);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
- The fma functions compute (x x y) + z, rounded as one ternary operation: they compute
+ The fma functions compute (x y) + z, rounded as one ternary operation: they compute
the value (as if) to infinite precision and round once to the result format, according to the
current rounding mode. A range error may occur.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
- The fma functions return (x x y) + z, rounded as one ternary operation.
+ The fma functions return (x y) + z, rounded as one ternary operation.
the synopses in this subclause, real-floating indicates that the argument shall be an
expression of real floating type.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isgreater(real-floating x, real-floating y);</pre>
-<h6>Description</h6>
+ int isgreater(real-floating x, real-floating y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isgreaterequal(real-floating x, real-floating y);</pre>
-<h6>Description</h6>
+ int isgreaterequal(real-floating x, real-floating y);
+</pre>
+<p><b>Description</b>
<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
<!--page 253 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isless(real-floating x, real-floating y);</pre>
-<h6>Description</h6>
+ int isless(real-floating x, real-floating y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int islessequal(real-floating x, real-floating y);</pre>
-<h6>Description</h6>
+ int islessequal(real-floating x, real-floating y);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int islessgreater(real-floating x, real-floating y);</pre>
-<h6>Description</h6>
+ int islessgreater(real-floating x, real-floating y);
+</pre>
+<p><b>Description</b>
<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
the ''invalid'' floating-point exception when x and y are unordered (nor does it evaluate x
and y twice).
<!--page 254 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
- int isunordered(real-floating x, real-floating y);</pre>
-<h6>Description</h6>
+ int isunordered(real-floating x, real-floating y);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The isunordered macro determines whether its arguments are unordered.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The isunordered macro returns 1 if its arguments are unordered and 0 otherwise.
<!--page 255 -->
-<h3><a name="7.13" href="#7.13">7.13 Nonlocal jumps <setjmp.h></a></h3>
+<h3><a name="7.13" href="#7.13">7.13 Nonlocal jumps <setjmp.h></a></h3>
<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>
- jmp_buf</pre>
+ jmp_buf
+</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
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note216" href="#note216">216)</a> These functions are useful for dealing with unusual conditions encountered in a low-level function of
a program.
</small>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
- int setjmp(jmp_buf env);</pre>
-<h6>Description</h6>
+ int setjmp(jmp_buf env);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The setjmp macro saves its calling environment in its jmp_buf argument for later use
by the longjmp function.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
- Environmental limits
+<p><b>Environmental limits</b>
<p><!--para 4 -->
An invocation of the setjmp macro shall appear only in one of the following contexts:
<ul>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
- void longjmp(jmp_buf env, int val);</pre>
-<h6>Description</h6>
+ void longjmp(jmp_buf env, int val);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
- }</pre>
+ }
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h3><a name="7.14" href="#7.14">7.14 Signal handling <signal.h></a></h3>
+<h3><a name="7.14" href="#7.14">7.14 Signal handling <signal.h></a></h3>
<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>
- sig_atomic_t</pre>
+ sig_atomic_t
+</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 -->
<pre>
SIG_DFL
SIG_ERR
- SIG_IGN</pre>
+ SIG_IGN
+</pre>
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:
-<p><!--para 4 -->
<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
- SIGTERM a termination request sent to the program</pre>
+ SIGTERM a termination request sent to the program
+</pre>
+<p><!--para 4 -->
An implementation need not generate any of these signals, except as a result of explicit
calls to the raise function. Additional signals and pointers to undeclarable functions,
with macro definitions beginning, respectively, with the letters SIG and an uppercase
<!--page 259 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.14"><signal.h></a>
- void (*signal(int sig, void (*func)(int)))(int);</pre>
-<h6>Description</h6>
+ void (*signal(int sig, void (*func)(int)))(int);
+</pre>
+<p><b>Description</b>
<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 6 -->
At program startup, the equivalent of
<pre>
- signal(sig, SIG_IGN);</pre>
+ signal(sig, SIG_IGN);
+</pre>
<!--page 260 -->
may be executed for some signals selected in an implementation-defined manner; the
equivalent of
<pre>
- signal(sig, SIG_DFL);</pre>
+ signal(sig, SIG_DFL);
+</pre>
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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.14"><signal.h></a>
- int raise(int sig);</pre>
-<h6>Description</h6>
+ int raise(int sig);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The raise function returns zero if successful, nonzero if unsuccessful.
<!--page 261 -->
-<h3><a name="7.15" href="#7.15">7.15 Variable arguments <stdarg.h></a></h3>
+<h3><a name="7.15" href="#7.15">7.15 Variable arguments <stdarg.h></a></h3>
<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 3 -->
The type declared is
<pre>
- va_list</pre>
+ va_list
+</pre>
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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
function.
<h5><a name="7.15.1.1" href="#7.15.1.1">7.15.1.1 The va_arg macro</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
- type va_arg(va_list ap, type);</pre>
-<h6>Description</h6>
+ type va_arg(va_list ap, type);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
- void va_copy(va_list dest, va_list src);</pre>
-<h6>Description</h6>
+ void va_copy(va_list dest, va_list src);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
- void va_end(va_list ap);</pre>
-<h6>Description</h6>
+ void va_end(va_list ap);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
- void va_start(va_list ap, parmN);</pre>
-<h6>Description</h6>
+ void va_start(va_list ap, parmN);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The va_start macro shall be invoked before any access to the unnamed arguments.
<p><!--para 3 -->
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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 5 -->
The va_start macro returns no value.
<p><!--para 6 -->
va_list ap;
char *array[MAXARGS];
int ptr_no = 0;
- if (n_ptrs > MAXARGS)
- n_ptrs = MAXARGS;
- va_start(ap, n_ptrs);
- while (ptr_no < n_ptrs)
- array[ptr_no++] = va_arg(ap, char *);
- va_end(ap);
- f2(n_ptrs, array);
- }</pre>
+ if (n_ptrs > MAXARGS)
+ n_ptrs = MAXARGS;
+ va_start(ap, n_ptrs);
+ while (ptr_no < n_ptrs)
+ array[ptr_no++] = va_arg(ap, char *);
+ va_end(ap);
+ f2(n_ptrs, array);
+ }
+</pre>
Each call to f1 is required to have visible the definition of the function or a declaration such as
<pre>
- void f1(int, ...);</pre>
+ void f1(int, ...);
+</pre>
<p><!--para 7 -->
EXAMPLE 2 The function f3 is similar, but saves the status of the variable argument list after the
array[ptr_no++] = va_arg(ap_save, char *);
va_end(ap_save);
f4(n_ptrs, array);
- }</pre>
+ }
+</pre>
-<h3><a name="7.16" href="#7.16">7.16 Boolean type and values <stdbool.h></a></h3>
+<h3><a name="7.16" href="#7.16">7.16 Boolean type and values <stdbool.h></a></h3>
<p><!--para 1 -->
The header <a href="#7.16"><stdbool.h></a> defines four macros.
<p><!--para 2 -->
The macro
<pre>
- bool</pre>
+ bool
+</pre>
expands to _Bool.
<p><!--para 3 -->
The remaining three macros are suitable for use in #if preprocessing directives. They
are
<pre>
- true</pre>
+ true
+</pre>
which expands to the integer constant 1,
<pre>
- false</pre>
+ false
+</pre>
which expands to the integer constant 0, and
<pre>
- __bool_true_false_are_defined</pre>
+ __bool_true_false_are_defined
+</pre>
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
<!--page 266 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note222" href="#note222">222)</a> See ''future library directions'' (<a href="#7.26.7">7.26.7</a>).
</small>
-<h3><a name="7.17" href="#7.17">7.17 Common definitions <stddef.h></a></h3>
+<h3><a name="7.17" href="#7.17">7.17 Common definitions <stddef.h></a></h3>
<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>
- ptrdiff_t</pre>
+ ptrdiff_t
+</pre>
which is the signed integer type of the result of subtracting two pointers;
<pre>
- size_t</pre>
+ size_t
+</pre>
which is the unsigned integer type of the result of the sizeof operator; and
<pre>
- wchar_t</pre>
+ wchar_t
+</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
<p><!--para 3 -->
The macros are
<pre>
- NULL</pre>
+ NULL
+</pre>
which expands to an implementation-defined null pointer constant; and
<pre>
- offsetof(type, member-designator)</pre>
+ offsetof(type, member-designator)
+</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>
- static type t;</pre>
+ static type t;
+</pre>
then the expression &(t.member-designator) evaluates to an address constant. (If the
specified member is a bit-field, the behavior is undefined.)
- Recommended practice
+<p><b>Recommended practice</b>
<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><b> Forward references</b>: localization (<a href="#7.11">7.11</a>).
<!--page 267 -->
-<h3><a name="7.18" href="#7.18">7.18 Integer types <stdint.h></a></h3>
+<h3><a name="7.18" href="#7.18">7.18 Integer types <stdint.h></a></h3>
<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'').
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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_least64_t uint_least64_t</pre>
+ int_least64_t uint_least64_t
+</pre>
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>
int_fast8_t uint_fast8_t
int_fast16_t uint_fast16_t
int_fast32_t uint_fast32_t
- int_fast64_t uint_fast64_t</pre>
+ int_fast64_t uint_fast64_t
+</pre>
All other types of this form are optional.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
- intptr_t</pre>
+ intptr_t
+</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>
- uintptr_t</pre>
+ uintptr_t
+</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>
The following type designates a signed integer type capable of representing any value of
any signed integer type:
<pre>
- intmax_t</pre>
+ intmax_t
+</pre>
The following type designates an unsigned integer type capable of representing any value
of any unsigned integer type:
<pre>
- uintmax_t</pre>
+ uintmax_t
+</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>
magnitude (absolute value) than the corresponding value given below, with the same sign,
except where stated to be exactly the given value.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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><!--para 1 -->
<ul>
<li> minimum values of exact-width signed integer types
- INTN_MIN exactly -(2 N -1 )
+<pre>
+ INTN_MIN exactly -(2<sup>N-1</sup>)
+</pre>
<li> maximum values of exact-width signed integer types
- INTN_MAX exactly 2 N -1 - 1
+<pre>
+ INTN_MAX exactly 2<sup>N-1</sup> - 1
+</pre>
<li> maximum values of exact-width unsigned integer types
- UINTN_MAX exactly 2 N - 1
+<pre>
+ UINTN_MAX exactly 2<sup>N</sup> - 1
+</pre>
</ul>
<h5><a name="7.18.2.2" href="#7.18.2.2">7.18.2.2 Limits of minimum-width integer types</a></h5>
<p><!--para 1 -->
<ul>
<li> minimum values of minimum-width signed integer types
- INT_LEASTN_MIN -(2 N -1 - 1)
+<pre>
+ INT_LEASTN_MIN -(2<sup>N-1</sup> - 1)
+</pre>
<li> maximum values of minimum-width signed integer types
- INT_LEASTN_MAX 2 N -1 - 1
+<pre>
+ INT_LEASTN_MAX 2<sup>N-1</sup> - 1
+</pre>
<li> maximum values of minimum-width unsigned integer types
- UINT_LEASTN_MAX 2N - 1
+<pre>
+ UINT_LEASTN_MAX 2<sup>N</sup> - 1
+</pre>
</ul>
<h5><a name="7.18.2.3" href="#7.18.2.3">7.18.2.3 Limits of fastest minimum-width integer types</a></h5>
<p><!--para 1 -->
<ul>
<li> minimum values of fastest minimum-width signed integer types
- INT_FASTN_MIN -(2 N -1 - 1)
+<pre>
+ INT_FASTN_MIN -(2<sup>N-1</sup> - 1)
+</pre>
<li> maximum values of fastest minimum-width signed integer types
- INT_FASTN_MAX 2 N -1 - 1
+<pre>
+ INT_FASTN_MAX 2<sup>N-1</sup> - 1
+</pre>
<li> maximum values of fastest minimum-width unsigned integer types
- UINT_FASTN_MAX 2N - 1
+<pre>
+ UINT_FASTN_MAX 2<sup>N</sup> - 1
+</pre>
</ul>
<h5><a name="7.18.2.4" href="#7.18.2.4">7.18.2.4 Limits of integer types capable of holding object pointers</a></h5>
<ul>
<li> minimum value of pointer-holding signed integer type
<pre>
- INTPTR_MIN -(215 - 1)</pre>
+ INTPTR_MIN -(2<sup>15</sup> - 1)
+</pre>
<li> maximum value of pointer-holding signed integer type
<!--page 271 -->
<pre>
- INTPTR_MAX 215 - 1</pre>
+ INTPTR_MAX 2<sup>15</sup> - 1
+</pre>
<li> maximum value of pointer-holding unsigned integer type
- UINTPTR_MAX 216 - 1
+<pre>
+ UINTPTR_MAX 2<sup>16</sup> - 1
+</pre>
</ul>
<h5><a name="7.18.2.5" href="#7.18.2.5">7.18.2.5 Limits of greatest-width integer types</a></h5>
<p><!--para 1 -->
<ul>
<li> minimum value of greatest-width signed integer type
- INTMAX_MIN -(263 - 1)
+<pre>
+ INTMAX_MIN -(2<sup>63</sup> - 1)
+</pre>
<li> maximum value of greatest-width signed integer type
- INTMAX_MAX 263 - 1
+<pre>
+ INTMAX_MAX 2<sup>63</sup> - 1
+</pre>
<li> maximum value of greatest-width unsigned integer type
- UINTMAX_MAX 264 - 1
+<pre>
+ UINTMAX_MAX 2<sup>64</sup> - 1
+</pre>
</ul>
<h4><a name="7.18.3" href="#7.18.3">7.18.3 Limits of other integer types</a></h4>
actually provides.<sup><a href="#note228"><b>228)</b></a></sup>
<ul>
<li> limits of ptrdiff_t
- PTRDIFF_MIN -65535
- PTRDIFF_MAX +65535
+<pre>
+ PTRDIFF_MIN -65535
+ PTRDIFF_MAX +65535
+</pre>
<li> limits of sig_atomic_t
- SIG_ATOMIC_MIN see below
- SIG_ATOMIC_MAX see below
+<pre>
+ SIG_ATOMIC_MIN see below
+ SIG_ATOMIC_MAX see below
+</pre>
<li> limit of size_t
- SIZE_MAX 65535
+<pre>
+ SIZE_MAX 65535
+</pre>
<li> limits of wchar_t
-
-
<!--page 272 -->
- WCHAR_MIN see below
- WCHAR_MAX see below
+<pre>
+ WCHAR_MIN see below
+ WCHAR_MAX see below
+</pre>
<li> limits of wint_t
- WINT_MIN see below
- WINT_MAX see below
+<pre>
+ WINT_MIN see below
+ WINT_MAX see below
+</pre>
</ul>
<p><!--para 3 -->
If sig_atomic_t (see <a href="#7.14">7.14</a>) is defined as a signed integer type, the value of
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<!--page 273 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
- INTMAX_C(value)</pre>
+ INTMAX_C(value)
+</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>
- UINTMAX_C(value)</pre>
+ UINTMAX_C(value)
+</pre>
-<h3><a name="7.19" href="#7.19">7.19 Input/output <stdio.h></a></h3>
+<h3><a name="7.19" href="#7.19">7.19 Input/output <stdio.h></a></h3>
<h4><a name="7.19.1" href="#7.19.1">7.19.1 Introduction</a></h4>
<p><!--para 1 -->
<p><!--para 2 -->
The types declared are size_t (described in <a href="#7.17">7.17</a>);
<pre>
- FILE</pre>
+ FILE
+</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>
- fpos_t</pre>
+ fpos_t
+</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 -->
<pre>
_IOFBF
_IOLBF
- _IONBF</pre>
+ _IONBF
+</pre>
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the setvbuf function;
<pre>
- BUFSIZ</pre>
+ BUFSIZ
+</pre>
which expands to an integer constant expression that is the size of the buffer used by the
setbuf function;
<pre>
- EOF</pre>
+ EOF
+</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>
- FOPEN_MAX</pre>
+ FOPEN_MAX
+</pre>
which expands to an integer constant expression that is the minimum number of files that
the implementation guarantees can be open simultaneously;
<pre>
- FILENAME_MAX</pre>
+ FILENAME_MAX
+</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>
- L_tmpnam</pre>
+ L_tmpnam
+</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
- SEEK_SET</pre>
+ SEEK_SET
+</pre>
which expand to integer constant expressions with distinct values, suitable for use as the
third argument to the fseek function;
<pre>
- TMP_MAX</pre>
+ TMP_MAX
+</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
- stdout</pre>
+ stdout
+</pre>
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
- Environmental limits
+<p><b>Environmental limits</b>
<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
<!--page 278 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
<!--page 279 -->
<p><!--para 7 -->
At program startup, three text streams are predefined and need not be opened explicitly
-<ul>
-<li> standard input (for reading conventional input), standard output (for writing
-</ul>
+ -- standard input (for reading conventional input), standard output (for writing
conventional output), and standard error (for writing diagnostic output). As initially
opened, the standard error stream is not fully buffered; the standard input and standard
output streams are fully buffered if and only if the stream can be determined not to refer
multibyte character. The wide character input/output functions and the byte input/output
functions store the value of the macro EILSEQ in errno if and only if an encoding error
occurs.
- Environmental limits
+<p><b>Environmental limits</b>
<p><!--para 15 -->
The value of FOPEN_MAX shall be at least eight, including the three standard text
streams.
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int remove(const char *filename);</pre>
-<h6>Description</h6>
+ int remove(const char *filename);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int rename(const char *old, const char *new);</pre>
-<h6>Description</h6>
+ int rename(const char *old, const char *new);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- FILE *tmpfile(void);</pre>
-<h6>Description</h6>
+ FILE *tmpfile(void);
+</pre>
+<p><b>Description</b>
<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.
- Recommended practice
+<p><b>Recommended practice</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- char *tmpnam(char *s);</pre>
-<h6>Description</h6>
+ char *tmpnam(char *s);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
- Environmental limits
+<p><b>Environmental limits</b>
<p><!--para 6 -->
The value of the macro TMP_MAX shall be at least 25.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int fclose(FILE *stream);</pre>
-<h6>Description</h6>
+ int fclose(FILE *stream);
+</pre>
+<p><b>Description</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<!--page 283 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int fflush(FILE *stream);</pre>
-<h6>Description</h6>
+ int fflush(FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *fopen(const char * restrict filename,
- const char * restrict mode);</pre>
-<h6>Description</h6>
+ const char * restrict mode);
+</pre>
+<p><b>Description</b>
<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 3 -->
The argument mode points to a string. If the string is one of the following, the file is
open in the indicated mode. Otherwise, the behavior is undefined.<sup><a href="#note237"><b>237)</b></a></sup>
- r open text file for reading
- w truncate to zero length or create text file for writing
- a append; open or create text file for writing at end-of-file
- rb open binary file for reading
- wb truncate to zero length or create binary file for writing
- ab append; open or create binary file for writing at end-of-file
- r+ open text file for update (reading and writing)
- w+ truncate to zero length or create text file for update
- a+ append; open or create text file for update, writing at end-of-file
-
-
-
+<dl>
+<dt> r <dd>open text file for reading
+<dt> w <dd>truncate to zero length or create text file for writing
+<dt> a <dd>append; open or create text file for writing at end-of-file
+<dt> rb <dd>open binary file for reading
+<dt> wb <dd>truncate to zero length or create binary file for writing
+<dt> ab <dd><dd>append; open or create binary file for writing at end-of-file
+<dt> r+ <dd>open text file for update (reading and writing)
+<dt> w+ <dd>truncate to zero length or create text file for update
+<dt> a+ <dd>append; open or create text file for update, writing at end-of-file
<!--page 284 -->
- r+b or rb+ open binary file for update (reading and writing)
- w+b or wb+ truncate to zero length or create binary file for update
- a+b or ab+ append; open or create binary file for update, writing at end-of-file
+<dt> r+b or rb+ <dd>open binary file for update (reading and writing)
+<dt> w+b or wb+ <dd>truncate to zero length or create binary file for update
+<dt> a+b or ab+ <dd>append; open or create binary file for update, writing at end-of-file
+</dl>
<p><!--para 4 -->
Opening a file with read mode ('r' as the first character in the mode argument) fails if
the file does not exist or cannot be read.
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *freopen(const char * restrict filename,
const char * restrict mode,
- FILE * restrict stream);</pre>
-<h6>Description</h6>
+ FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 5 -->
The freopen function returns a null pointer if the open operation fails. Otherwise,
freopen returns the value of stream.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void setbuf(FILE * restrict stream,
- char * restrict buf);</pre>
-<h6>Description</h6>
+ char * restrict buf);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int setvbuf(FILE * restrict stream,
char * restrict buf,
- int mode, size_t size);</pre>
+ int mode, size_t size);
+</pre>
<!--page 286 -->
-<h6>Description</h6>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fprintf(FILE * restrict stream,
- const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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
precision were omitted.
<p><!--para 6 -->
The flag characters and their meanings are:
- - The result of the conversion is left-justified within the field. (It is right-justified if
-<pre>
- this flag is not specified.)</pre>
- + The result of a signed conversion always begins with a plus or minus sign. (It
-<pre>
- begins with a sign only when a negative value is converted if this flag is not</pre>
-
-
-
+<dl>
+<dt> - <dd> The result of the conversion is left-justified within the field. (It is right-justified if
+ this flag is not specified.)
+<dt> + <dd> The result of a signed conversion always begins with a plus or minus sign. (It
+ begins with a sign only when a negative value is converted if this flag is not
<!--page 288 -->
-<pre>
- specified.)<sup><a href="#note242"><b>242)</b></a></sup></pre>
- space If the first character of a signed conversion is not a sign, or if a signed conversion
-<pre>
+ specified.)<sup><a href="#note242"><b>242)</b></a></sup>
+<dt> space<dd> If the first character of a signed conversion is not a sign, or if a signed conversion
results in no characters, a space is prefixed to the result. If the space and + flags
- both appear, the space flag is ignored.</pre>
- # The result is converted to an ''alternative form''. For o conversion, it increases
-<pre>
+ both appear, the space flag is ignored.
+<dt> # <dd> The result is converted to an ''alternative form''. For o conversion, it increases
the precision, if and only if necessary, to force the first digit of the result to be a
zero (if the value and precision are both 0, a single 0 is printed). For x (or X)
conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,
contains a decimal-point character, even if no digits follow it. (Normally, a
decimal-point character appears in the result of these conversions only if a digit
follows it.) For g and G conversions, trailing zeros are not removed from the
- result. For other conversions, the behavior is undefined.</pre>
- 0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-<p><!--para 7 -->
-<pre>
+ result. For other conversions, the behavior is undefined.
+<dt> 0 <dd> For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
(following any indication of sign or base) are used to pad to the field width rather
than performing space padding, except when converting an infinity or NaN. If the
0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X
conversions, if a precision is specified, the 0 flag is ignored. For other
- conversions, the behavior is undefined.</pre>
+ conversions, the behavior is undefined.
+</dl>
+<p><!--para 7 -->
The length modifiers and their meanings are:
- hh Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+<dl>
+<dt> hh <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
signed char or unsigned char argument (the argument will have
been promoted according to the integer promotions, but its value shall be
converted to signed char or unsigned char before printing); or that
a following n conversion specifier applies to a pointer to a signed char
- argument.</pre>
- h Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ argument.
+<dt> h <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
short int or unsigned short int argument (the argument will
have been promoted according to the integer promotions, but its value shall
be converted to short int or unsigned short int before printing);
or that a following n conversion specifier applies to a pointer to a short
- int argument.</pre>
- l (ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ int argument.
+<dt> l (ell) <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
long int or unsigned long int argument; that a following n
- conversion specifier applies to a pointer to a long int argument; that a</pre>
-
+ conversion specifier applies to a pointer to a long int argument; that a
<!--page 289 -->
-<pre>
following c conversion specifier applies to a wint_t argument; that a
following s conversion specifier applies to a pointer to a wchar_t
argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion
- specifier.</pre>
- ll (ell-ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ specifier.
+<dt> ll (ell-ell)<dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
long long int or unsigned long long int argument; or that a
following n conversion specifier applies to a pointer to a long long int
- argument.</pre>
- j Specifies that a following d, i, o, u, x, or X conversion specifier applies to
-<pre>
+ argument.
+<dt> j <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to
an intmax_t or uintmax_t argument; or that a following n conversion
- specifier applies to a pointer to an intmax_t argument.</pre>
- z Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ specifier applies to a pointer to an intmax_t argument.
+<dt> z <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
size_t or the corresponding signed integer type argument; or that a
following n conversion specifier applies to a pointer to a signed integer type
- corresponding to size_t argument.</pre>
- t Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ corresponding to size_t argument.
+<dt> t <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
ptrdiff_t or the corresponding unsigned integer type argument; or that a
following n conversion specifier applies to a pointer to a ptrdiff_t
- argument.</pre>
- L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-<pre>
- applies to a long double argument.</pre>
- If a length modifier appears with any conversion specifier other than as specified above,
+ argument.
+<dt> L <dd> Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
+ applies to a long double argument.
+</dl>
+If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
<p><!--para 8 -->
The conversion specifiers and their meanings are:
- d,i The int argument is converted to signed decimal in the style [-]dddd. The
-<pre>
+<dl>
+<dt> d,i <dd> The int argument is converted to signed decimal in the style [-]dddd. The
precision specifies the minimum number of digits to appear; if the value
being converted can be represented in fewer digits, it is expanded with
leading zeros. The default precision is 1. The result of converting a zero
- value with a precision of zero is no characters.</pre>
- o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned
+ value with a precision of zero is no characters.
+<dt> o,u,x,X<dd> The unsigned int argument is converted to unsigned octal (o), unsigned
<!--page 290 -->
-<pre>
decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the
letters abcdef are used for x conversion and the letters ABCDEF for X
conversion. The precision specifies the minimum number of digits to appear;
if the value being converted can be represented in fewer digits, it is expanded
with leading zeros. The default precision is 1. The result of converting a
- zero value with a precision of zero is no characters.</pre>
- f,F A double argument representing a floating-point number is converted to
-<pre>
+ zero value with a precision of zero is no characters.
+<dt> f,F <dd> A double argument representing a floating-point number is converted to
decimal notation in the style [-]ddd.ddd, where the number of digits after
the decimal-point character is equal to the precision specification. If the
precision is missing, it is taken as 6; if the precision is zero and the # flag is
[-]nan or [-]nan(n-char-sequence) -- which style, and the meaning of
any n-char-sequence, is implementation-defined. The F conversion specifier
produces INF, INFINITY, or NAN instead of inf, infinity, or nan,
- respectively.<sup><a href="#note243"><b>243)</b></a></sup></pre>
- e,E A double argument representing a floating-point number is converted in the
-<pre>
+ respectively.<sup><a href="#note243"><b>243)</b></a></sup>
+<dt> e,E <dd> A double argument representing a floating-point number is converted in the
style [-]d.ddd e(+-)dd, where there is one digit (which is nonzero if the
argument is nonzero) before the decimal-point character and the number of
digits after it is equal to the precision; if the precision is missing, it is taken as
and only as many more digits as necessary to represent the exponent. If the
value is zero, the exponent is zero.
A double argument representing an infinity or NaN is converted in the style
- of an f or F conversion specifier.</pre>
- g,G A double argument representing a floating-point number is converted in
-<pre>
+ of an f or F conversion specifier.
+<dt> g,G <dd> A double argument representing a floating-point number is converted in
style f or e (or in style F or E in the case of a G conversion specifier),
depending on the value converted and the precision. Let P equal the
precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero.
Then, if a conversion with style E would have an exponent of X :
- -- if P > X >= -4, the conversion is with style f (or F) and precision
+ <ul>
+ <li> if P > X >= -4, the conversion is with style f (or F) and precision
P - (X + 1).
- -- otherwise, the conversion is with style e (or E) and precision P - 1.
- Finally, unless the # flag is used, any trailing zeros are removed from the</pre>
-
+ <li> otherwise, the conversion is with style e (or E) and precision P - 1.
+ </ul>
+ Finally, unless the # flag is used, any trailing zeros are removed from the
<!--page 291 -->
-<pre>
fractional portion of the result and the decimal-point character is removed if
there is no fractional portion remaining.
A double argument representing an infinity or NaN is converted in the style
- of an f or F conversion specifier.</pre>
- a,A A double argument representing a floating-point number is converted in the
-<pre>
+ of an f or F conversion specifier.
+<dt> a,A <dd> A double argument representing a floating-point number is converted in the
style [-]0xh.hhhh p(+-)d, where there is one hexadecimal digit (which is
nonzero if the argument is a normalized floating-point number and is
otherwise unspecified) before the decimal-point character<sup><a href="#note244"><b>244)</b></a></sup> and the number
least one digit, and only as many more digits as necessary to represent the
decimal exponent of 2. If the value is zero, the exponent is zero.
A double argument representing an infinity or NaN is converted in the style
- of an f or F conversion specifier.</pre>
- c If no l length modifier is present, the int argument is converted to an
-<pre>
+ of an f or F conversion specifier.
+<dt> c <dd> If no l length modifier is present, the int argument is converted to an
unsigned char, and the resulting character is written.
If an l length modifier is present, the wint_t argument is converted as if by
an ls conversion specification with no precision and an argument that points
to the initial element of a two-element array of wchar_t, the first element
containing the wint_t argument to the lc conversion specification and the
- second a null wide character.</pre>
- s If no l length modifier is present, the argument shall be a pointer to the initial
-<pre>
- element of an array of character type.<sup><a href="#note246"><b>246)</b></a></sup> Characters from the array are</pre>
-
-
+ second a null wide character.
+<dt> s <dd> If no l length modifier is present, the argument shall be a pointer to the initial
+ element of an array of character type.<sup><a href="#note246"><b>246)</b></a></sup> Characters from the array are
<!--page 292 -->
-<pre>
written up to (but not including) the terminating null character. If the
precision is specified, no more than that many bytes are written. If the
precision is not specified or is greater than the size of the array, the array shall
written (including shift sequences, if any), and the array shall contain a null
wide character if, to equal the multibyte character sequence length given by
the precision, the function would need to access a wide character one past the
- end of the array. In no case is a partial multibyte character written.<sup><a href="#note247"><b>247)</b></a></sup></pre>
- p The argument shall be a pointer to void. The value of the pointer is
-<pre>
+ end of the array. In no case is a partial multibyte character written.<sup><a href="#note247"><b>247)</b></a></sup>
+<dt> p <dd> The argument shall be a pointer to void. The value of the pointer is
converted to a sequence of printing characters, in an implementation-defined
- manner.</pre>
- n The argument shall be a pointer to signed integer into which is written the
-<pre>
+ manner.
+<dt> n <dd> The argument shall be a pointer to signed integer into which is written the
number of characters written to the output stream so far by this call to
fprintf. No argument is converted, but one is consumed. If the conversion
specification includes any flags, a field width, or a precision, the behavior is
- undefined.</pre>
- % A % character is written. No argument is converted. The complete
+ undefined.
+<dt> % <dd> A % character is written. No argument is converted. The complete
+ conversion specification shall be %%.
+</dl>
<p><!--para 9 -->
-<pre>
- conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note248"><b>248)</b></a></sup> If any argument is
not the correct type for the corresponding conversion specification, the behavior is
undefined.
<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.
- Recommended practice
+<p><b>Recommended practice</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 14 -->
The fprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
- Environmental limits
+<p><b>Environmental limits</b>
<p><!--para 15 -->
The number of characters that can be produced by any single conversion shall be at least
4095.
int day, hour, min;
fprintf(stdout, "%s, %s %d, %.2d:%.2d\n",
weekday, month, day, hour, min);
- fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));</pre>
+ fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));
+</pre>
<p><!--para 17 -->
EXAMPLE 2 In this example, multibyte characters do not have a state-dependent encoding, and the
<p><!--para 18 -->
Given the following wide string with length seven,
<pre>
- static wchar_t wstr[] = L" X Yabc Z W";</pre>
+ static wchar_t wstr[] = L" X Yabc Z W";
+</pre>
the seven calls
<pre>
fprintf(stdout, "|1234567890123|\n");
fprintf(stdout, "|%13.10ls|\n", wstr);
fprintf(stdout, "|%13.11ls|\n", wstr);
fprintf(stdout, "|%13.15ls|\n", &wstr[2]);
- fprintf(stdout, "|%13lc|\n", (wint_t) wstr[5]);</pre>
+ fprintf(stdout, "|%13lc|\n", (wint_t) wstr[5]);
+</pre>
will print the following seven lines:
<pre>
|1234567890123|
| X Yabc Z|
| X Yabc Z W|
| abc Z W|
- | Z|</pre>
+ | Z|
+</pre>
<p><b> Forward references</b>: conversion state (<a href="#7.24.6">7.24.6</a>), the wcrtomb function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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="note244" href="#note244">244)</a> Binary implementations can choose the hexadecimal digit to the left of the decimal-point character so
that subsequent digits align to nibble (4-bit) boundaries.
</small>
-<p><small><a name="note245" href="#note245">245)</a> The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
+<p><small><a name="note245" href="#note245">245)</a> The precision p is sufficient to distinguish values of the source type if 16<sup>p-1</sup> > b n where b is
FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p
might suffice depending on the implementation's scheme for determining the digit to the left of the
decimal-point character.
</small>
<h5><a name="7.19.6.2" href="#7.19.6.2">7.19.6.2 The fscanf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fscanf(FILE * restrict stream,
- const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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
in the object, the behavior is undefined.
<p><!--para 11 -->
The length modifiers and their meanings are:
- hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
- to an argument with type pointer to signed char or unsigned char.</pre>
- h Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+<dl>
+<dt> hh <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
+ to an argument with type pointer to signed char or unsigned char.
+<dt> h <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to short int or unsigned short
- int.</pre>
- l (ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ int.
+<dt> l (ell) <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to long int or unsigned long
int; that a following a, A, e, E, f, F, g, or G conversion specifier applies to
an argument with type pointer to double; or that a following c, s, or [
- conversion specifier applies to an argument with type pointer to wchar_t.</pre>
- ll (ell-ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ conversion specifier applies to an argument with type pointer to wchar_t.
+<dt> ll (ell-ell)<dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to long long int or unsigned
- long long int.</pre>
- j Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
- to an argument with type pointer to intmax_t or uintmax_t.</pre>
- z Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ long long int.
+<dt> j <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
+ to an argument with type pointer to intmax_t or uintmax_t.
+<dt> z <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to size_t or the corresponding signed
- integer type.</pre>
- t Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ integer type.
+<dt> t <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to ptrdiff_t or the corresponding
- unsigned integer type.</pre>
- L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-<pre>
- applies to an argument with type pointer to long double.</pre>
+ unsigned integer type.
+<dt> L <dd> Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
+ applies to an argument with type pointer to long double.
+</dl>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
<p><!--para 12 -->
The conversion specifiers and their meanings are:
- d Matches an optionally signed decimal integer, whose format is the same as
-<pre>
+<dl>
+<dt> d <dd> Matches an optionally signed decimal integer, whose format is the same as
expected for the subject sequence of the strtol function with the value 10
for the base argument. The corresponding argument shall be a pointer to
- signed integer.</pre>
- i Matches an optionally signed integer, whose format is the same as expected
+ signed integer.
+<dt> i <dd> Matches an optionally signed integer, whose format is the same as expected
<!--page 297 -->
-<pre>
for the subject sequence of the strtol function with the value 0 for the
base argument. The corresponding argument shall be a pointer to signed
- integer.</pre>
- o Matches an optionally signed octal integer, whose format is the same as
-<pre>
+ integer.
+<dt> o <dd> Matches an optionally signed octal integer, whose format is the same as
expected for the subject sequence of the strtoul function with the value 8
for the base argument. The corresponding argument shall be a pointer to
- unsigned integer.</pre>
- u Matches an optionally signed decimal integer, whose format is the same as
-<pre>
+ unsigned integer.
+<dt> u <dd> Matches an optionally signed decimal integer, whose format is the same as
expected for the subject sequence of the strtoul function with the value 10
for the base argument. The corresponding argument shall be a pointer to
- unsigned integer.</pre>
- x Matches an optionally signed hexadecimal integer, whose format is the same
-<pre>
+ unsigned integer.
+<dt> x <dd> Matches an optionally signed hexadecimal integer, whose format is the same
as expected for the subject sequence of the strtoul function with the value
16 for the base argument. The corresponding argument shall be a pointer to
- unsigned integer.</pre>
- a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose
-<pre>
+ unsigned integer.
+<dt> a,e,f,g<dd> Matches an optionally signed floating-point number, infinity, or NaN, whose
format is the same as expected for the subject sequence of the strtod
- function. The corresponding argument shall be a pointer to floating.</pre>
- c Matches a sequence of characters of exactly the number specified by the field
-<pre>
+ function. The corresponding argument shall be a pointer to floating.
+<dt> c <dd> Matches a sequence of characters of exactly the number specified by the field
width (1 if no field width is present in the directive).<sup><a href="#note252"><b>252)</b></a></sup>
If no l length modifier is present, the corresponding argument shall be a
pointer to the initial element of a character array large enough to accept the
initialized to zero before the first multibyte character is converted. The
corresponding argument shall be a pointer to the initial element of an array of
wchar_t large enough to accept the resulting sequence of wide characters.
- No null wide character is added.</pre>
- s Matches a sequence of non-white-space characters.252)
-<pre>
+ No null wide character is added.
+<dt> s <dd> Matches a sequence of non-white-space characters.<sup><a href="#note252"><b>252)</b></a></sup>
If no l length modifier is present, the corresponding argument shall be a
pointer to the initial element of a character array large enough to accept the
sequence and a terminating null character, which will be added automatically.
- If an l length modifier is present, the input shall be a sequence of multibyte</pre>
-
-
+ If an l length modifier is present, the input shall be a sequence of multibyte
<!--page 298 -->
-<pre>
characters that begins in the initial shift state. Each multibyte character is
converted to a wide character as if by a call to the mbrtowc function, with
the conversion state described by an mbstate_t object initialized to zero
before the first multibyte character is converted. The corresponding argument
shall be a pointer to the initial element of an array of wchar_t large enough
to accept the sequence and the terminating null wide character, which will be
- added automatically.</pre>
- [ Matches a nonempty sequence of characters from a set of expected characters
-<pre>
- (the scanset).252)
+ added automatically.
+<dt> [ <dd> Matches a nonempty sequence of characters from a set of expected characters
+ (the scanset).<sup><a href="#note252"><b>252)</b></a></sup>
If no l length modifier is present, the corresponding argument shall be a
pointer to the initial element of a character array large enough to accept the
sequence and a terminating null character, which will be added automatically.
the first following right bracket character is the one that ends the
specification. If a - character is in the scanlist and is not the first, nor the
second where the first character is a ^, nor the last character, the behavior is
- implementation-defined.</pre>
- p Matches an implementation-defined set of sequences, which should be the
+ implementation-defined.
+<dt> p <dd> Matches an implementation-defined set of sequences, which should be the
<!--page 299 -->
-<pre>
same as the set of sequences that may be produced by the %p conversion of
the fprintf function. The corresponding argument shall be a pointer to a
pointer to void. The input item is converted to a pointer value in an
implementation-defined manner. If the input item is a value converted earlier
during the same program execution, the pointer that results shall compare
- equal to that value; otherwise the behavior of the %p conversion is undefined.</pre>
- n No input is consumed. The corresponding argument shall be a pointer to
-<pre>
+ equal to that value; otherwise the behavior of the %p conversion is undefined.
+<dt> n <dd> No input is consumed. The corresponding argument shall be a pointer to
signed integer into which is to be written the number of characters read from
the input stream so far by this call to the fscanf function. Execution of a
%n directive does not increment the assignment count returned at the
completion of execution of the fscanf function. No argument is converted,
but one is consumed. If the conversion specification includes an assignment-
- suppressing character or a field width, the behavior is undefined.</pre>
- % Matches a single % character; no conversion or assignment occurs. The
+ suppressing character or a field width, the behavior is undefined.
+<dt> % <dd> Matches a single % character; no conversion or assignment occurs. The
+ complete conversion specification shall be %%.
+</dl>
<p><!--para 13 -->
-<pre>
- complete conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note253"><b>253)</b></a></sup>
<p><!--para 14 -->
The conversion specifiers A, E, F, G, and X are also valid and behave the same as,
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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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];
- n = fscanf(stdin, "%d%f%s", &i, &x, name);</pre>
+ n = fscanf(stdin, "%d%f%s", &i, &x, name);
+</pre>
with the input line:
<pre>
- 25 54.32E-1 thompson</pre>
+ 25 54.32E-1 thompson
+</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.
#include <a href="#7.19"><stdio.h></a>
/* ... */
int i; float x; char name[50];
- fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name);</pre>
+ fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name);
+</pre>
with input:
<!--page 300 -->
<pre>
- 56789 0123 56a72</pre>
+ 56789 0123 56a72
+</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:
-<p><!--para 20 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
/* ... */
do {
count = fscanf(stdin, "%f%20s of %20s", &quant, units, item);
fscanf(stdin,"%*[^\n]");
- } while (!feof(stdin) && !ferror(stdin));</pre>
+ } while (!feof(stdin) && !ferror(stdin));
+</pre>
+<p><!--para 20 -->
If the stdin stream contains the following lines:
<pre>
2 quarts of oil
lots of luck
10.0LBS of
dirt
- 100ergs of energy</pre>
+ 100ergs of energy
+</pre>
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"
- count = EOF;</pre>
+ count = EOF;
+</pre>
<p><!--para 21 -->
EXAMPLE 4 In:
#include <a href="#7.19"><stdio.h></a>
/* ... */
int d1, d2, n1, n2, i;
- 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.
#include <a href="#7.19"><stdio.h></a>
/* ... */
char str[50];
- fscanf(stdin, "a%s", str);</pre>
+ fscanf(stdin, "a%s", str);
+</pre>
with the input line:
<pre>
- a(uparrow) X Y(downarrow) bc</pre>
+ a(uparrow) X Y(downarrow) bc
+</pre>
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 -->
#include <a href="#7.17"><stddef.h></a>
/* ... */
wchar_t wstr[50];
- fscanf(stdin, "a%ls", wstr);</pre>
+ fscanf(stdin, "a%ls", wstr);
+</pre>
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 -->
#include <a href="#7.17"><stddef.h></a>
/* ... */
wchar_t wstr[50];
- fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr);</pre>
+ fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr);
+</pre>
with the same input line will return zero due to a matching failure against the (downarrow) sequence in the format
string.
<p><!--para 26 -->
#include <a href="#7.17"><stddef.h></a>
/* ... */
wchar_t wstr[50];
- fscanf(stdin, "a(uparrow) Y(downarrow)%ls", wstr);</pre>
+ fscanf(stdin, "a(uparrow) Y(downarrow)%ls", wstr);
+</pre>
with the same input line, zero will again be returned, but stdin will be left with a partially consumed
multibyte character.
(<a href="#7.24.6">7.24.6</a>), the wcrtomb function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
<!--page 302 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="7.19.6.3" href="#7.19.6.3">7.19.6.3 The printf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int printf(const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ int printf(const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The printf function is equivalent to fprintf with the argument stdout interposed
before the arguments to printf.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int scanf(const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ int scanf(const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The scanf function is equivalent to fscanf with the argument stdin interposed
before the arguments to scanf.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
matching failure.
<h5><a name="7.19.6.5" href="#7.19.6.5">7.19.6.5 The snprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int snprintf(char * restrict s, size_t n,
- const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sprintf(char * restrict s,
- const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sscanf(const char * restrict s,
- const char * restrict format, ...);</pre>
-<h6>Description</h6>
+ const char * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 304 -->
<h5><a name="7.19.6.8" href="#7.19.6.8">7.19.6.8 The vfprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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);
- }</pre>
+ }
+</pre>
<!--page 305 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.254)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
+<p><b>Returns</b>
<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
early matching failure.
<h5><a name="7.19.6.10" href="#7.19.6.10">7.19.6.10 The vprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.254)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.254)
-<h6>Returns</h6>
+ macro.<sup><a href="#note254"><b>254)</b></a></sup>
+<p><b>Returns</b>
<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
early matching failure.
<h5><a name="7.19.6.12" href="#7.19.6.12">7.19.6.12 The vsnprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.254) If copying takes place between objects that overlap, the behavior is
+ va_end macro.<sup><a href="#note254"><b>254)</b></a></sup> If copying takes place between objects that overlap, the behavior is
undefined.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 307 -->
<h5><a name="7.19.6.13" href="#7.19.6.13">7.19.6.13 The vsprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.254) If copying takes place between objects that overlap, the behavior is
+ va_end macro.<sup><a href="#note254"><b>254)</b></a></sup> If copying takes place between objects that overlap, the behavior is
undefined.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.254)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int fgetc(FILE *stream);</pre>
-<h6>Description</h6>
+ int fgetc(FILE *stream);
+</pre>
+<p><b>Description</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
char *fgets(char * restrict s, int n,
- FILE * restrict stream);</pre>
-<h6>Description</h6>
+ FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 309 -->
<h5><a name="7.19.7.3" href="#7.19.7.3">7.19.7.3 The fputc function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int fputc(int c, FILE *stream);</pre>
-<h6>Description</h6>
+ int fputc(int c, FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fputs(const char * restrict s,
- FILE * restrict stream);</pre>
-<h6>Description</h6>
+ FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int getc(FILE *stream);</pre>
-<h6>Description</h6>
+ int getc(FILE *stream);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
getc returns EOF.
<h5><a name="7.19.7.6" href="#7.19.7.6">7.19.7.6 The getchar function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int getchar(void);</pre>
-<h6>Description</h6>
+ int getchar(void);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The getchar function is equivalent to getc with the argument stdin.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
getchar returns EOF.
<h5><a name="7.19.7.7" href="#7.19.7.7">7.19.7.7 The gets function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- char *gets(char *s);</pre>
-<h6>Description</h6>
+ char *gets(char *s);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 311 -->
<h5><a name="7.19.7.8" href="#7.19.7.8">7.19.7.8 The putc function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int putc(int c, FILE *stream);</pre>
-<h6>Description</h6>
+ int putc(int c, FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int putchar(int c);</pre>
-<h6>Description</h6>
+ int putchar(int c);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The putchar function is equivalent to putc with the second argument stdout.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int puts(const char *s);</pre>
-<h6>Description</h6>
+ int puts(const char *s);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int ungetc(int c, FILE *stream);</pre>
-<h6>Description</h6>
+ int ungetc(int c, FILE *stream);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 6 -->
The ungetc function returns the character pushed back after conversion, or EOF if the
operation fails.
<!--page 313 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fread(void * restrict ptr,
size_t size, size_t nmemb,
- FILE * restrict stream);</pre>
-<h6>Description</h6>
+ FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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,
unchanged.
<h5><a name="7.19.8.2" href="#7.19.8.2">7.19.8.2 The fwrite function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- FILE * restrict stream);</pre>
-<h6>Description</h6>
+ FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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,
error occurs, the resulting value of the file position indicator for the stream is
indeterminate.
<!--page 314 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fgetpos(FILE * restrict stream,
- fpos_t * restrict pos);</pre>
-<h6>Description</h6>
+ fpos_t * restrict pos);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int fseek(FILE *stream, long int offset, int whence);</pre>
-<h6>Description</h6>
+ int fseek(FILE *stream, long int offset, int whence);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int fsetpos(FILE *stream, const fpos_t *pos);</pre>
-<h6>Description</h6>
+ int fsetpos(FILE *stream, const fpos_t *pos);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- long int ftell(FILE *stream);</pre>
-<h6>Description</h6>
+ long int ftell(FILE *stream);
+</pre>
+<p><b>Description</b>
<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
return values is not necessarily a meaningful measure of the number of characters written
<!--page 316 -->
or read.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- void rewind(FILE *stream);</pre>
-<h6>Description</h6>
+ void rewind(FILE *stream);
+</pre>
+<p><b>Description</b>
<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>
- (void)fseek(stream, 0L, SEEK_SET)</pre>
+ (void)fseek(stream, 0L, SEEK_SET)
+</pre>
except that the error indicator for the stream is also cleared.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- void clearerr(FILE *stream);</pre>
-<h6>Description</h6>
+ void clearerr(FILE *stream);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The clearerr function clears the end-of-file and error indicators for the stream pointed
to by stream.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int feof(FILE *stream);</pre>
-<h6>Description</h6>
+ int feof(FILE *stream);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The feof function tests the end-of-file indicator for the stream pointed to by stream.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- int ferror(FILE *stream);</pre>
-<h6>Description</h6>
+ int ferror(FILE *stream);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The ferror function tests the error indicator for the stream pointed to by stream.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
- void perror(const char *s);</pre>
-<h6>Description</h6>
+ void perror(const char *s);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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 -->
-<h3><a name="7.20" href="#7.20">7.20 General utilities <stdlib.h></a></h3>
+<h3><a name="7.20" href="#7.20">7.20 General utilities <stdlib.h></a></h3>
<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>
- div_t</pre>
+ div_t
+</pre>
which is a structure type that is the type of the value returned by the div function,
<pre>
- ldiv_t</pre>
+ ldiv_t
+</pre>
which is a structure type that is the type of the value returned by the ldiv function, and
<pre>
- lldiv_t</pre>
+ lldiv_t
+</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>
- EXIT_FAILURE</pre>
+ EXIT_FAILURE
+</pre>
and
<pre>
- EXIT_SUCCESS</pre>
+ EXIT_SUCCESS
+</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>
- RAND_MAX</pre>
+ RAND_MAX
+</pre>
which expands to an integer constant expression that is the maximum value returned by
the rand function; and
<pre>
- MB_CUR_MAX</pre>
+ MB_CUR_MAX
+</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.
<!--page 319 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note257" href="#note257">257)</a> See ''future library directions'' (<a href="#7.26.10">7.26.10</a>).
</small>
behavior is undefined.
<h5><a name="7.20.1.1" href="#7.20.1.1">7.20.1.1 The atof function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- double atof(const char *nptr);</pre>
-<h6>Description</h6>
+ double atof(const char *nptr);
+</pre>
+<p><b>Description</b>
<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>
- strtod(nptr, (char **)NULL)</pre>
-<h6>Returns</h6>
+ strtod(nptr, (char **)NULL)
+</pre>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int atoi(const char *nptr);
long int atol(const char *nptr);
- long long int atoll(const char *nptr);</pre>
-<h6>Description</h6>
+ long long int atoll(const char *nptr);
+</pre>
+<p><b>Description</b>
<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)
- atoll: strtoll(nptr, (char **)NULL, 10)</pre>
-<h6>Returns</h6>
+ atoll: strtoll(nptr, (char **)NULL, 10)
+</pre>
+<p><b>Returns</b>
<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
<!--page 320 -->
<h5><a name="7.20.1.3" href="#7.20.1.3">7.20.1.3 The strtod, strtof, and strtold functions</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
float strtof(const char * restrict nptr,
char ** restrict endptr);
long double strtold(const char * restrict nptr,
- char ** restrict endptr);</pre>
-<h6>Description</h6>
+ char ** restrict endptr);
+</pre>
+<p><b>Description</b>
<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,
<li> a 0x or 0X, then a nonempty sequence of hexadecimal digits optionally containing a
decimal-point character, then an optional binary exponent part as defined in <a href="#6.4.4.2">6.4.4.2</a>;
<li> INF or INFINITY, ignoring case
-<li> NAN or NAN(n-char-sequenceopt), ignoring case in the NAN part, where:
+<li> NAN or NAN(n-char-sequence<sub>opt</sub>), ignoring case in the NAN part, where:
<pre>
n-char-sequence:
digit
nondigit
n-char-sequence digit
- n-char-sequence nondigit</pre>
+ n-char-sequence nondigit
+</pre>
</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
the subject sequence begins with a minus sign, the sequence is interpreted as negated.<sup><a href="#note258"><b>258)</b></a></sup>
A character sequence INF or INFINITY is interpreted as an infinity, if representable in
the return type, else like a floating constant that is too large for the range of the return
- type. A character sequence NAN or NAN(n-char-sequenceopt), is interpreted as a quiet
+ type. A character sequence NAN or NAN(n-char-sequence<sub>opt</sub>), is interpreted as a quiet
NaN, if supported in the return type, else like a subject sequence part that does not have
the expected form; the meaning of the n-char sequences is implementation-defined.<sup><a href="#note259"><b>259)</b></a></sup> A
pointer to the final string is stored in the object pointed to by endptr, provided that
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
- Recommended practice
+<p><b>Recommended practice</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
unsigned long long int strtoull(
const char * restrict nptr,
char ** restrict endptr,
- int base);</pre>
-<h6>Description</h6>
+ int base);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- int rand(void);</pre>
-<h6>Description</h6>
+ int rand(void);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 4 -->
The rand function returns a pseudo-random integer.
- Environmental limits
+<p><b>Environmental limits</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void srand(unsigned int seed);</pre>
-<h6>Description</h6>
+ void srand(unsigned int seed);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 4 -->
The srand function returns no value.
<p><!--para 5 -->
void srand(unsigned int seed)
{
next = seed;
- }</pre>
+ }
+</pre>
<h4><a name="7.20.3" href="#7.20.3">7.20.3 Memory management functions</a></h4>
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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void *calloc(size_t nmemb, size_t size);</pre>
-<h6>Description</h6>
+ void *calloc(size_t nmemb, size_t size);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The calloc function returns either a null pointer or a pointer to the allocated space.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void free(void *ptr);</pre>
-<h6>Description</h6>
+ void free(void *ptr);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void *malloc(size_t size);</pre>
-<h6>Description</h6>
+ void *malloc(size_t size);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The malloc function allocates space for an object whose size is specified by size and
whose value is indeterminate.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void *realloc(void *ptr, size_t size);</pre>
-<h6>Description</h6>
+ void *realloc(void *ptr, size_t size);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void abort(void);</pre>
-<h6>Description</h6>
+ void abort(void);
+</pre>
+<p><b>Description</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- int atexit(void (*func)(void));</pre>
-<h6>Description</h6>
+ int atexit(void (*func)(void));
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The atexit function registers the function pointed to by func, to be called without
arguments at normal program termination.
- Environmental limits
+<p><b>Environmental limits</b>
<p><!--para 3 -->
The implementation shall support the registration of at least 32 functions.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void exit(int status);</pre>
-<h6>Description</h6>
+ void exit(int status);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 6 -->
The exit function cannot return to its caller.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- void _Exit(int status);</pre>
-<h6>Description</h6>
+ void _Exit(int status);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The _Exit function cannot return to its caller.
<!--page 329 -->
<h5><a name="7.20.4.5" href="#7.20.4.5">7.20.4.5 The getenv function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- char *getenv(const char *name);</pre>
-<h6>Description</h6>
+ char *getenv(const char *name);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- int system(const char *string);</pre>
-<h6>Description</h6>
+ int system(const char *string);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
- (char *)p < (char *)base + nmemb * size</pre>
+ (char *)p < (char *)base + nmemb * size
+</pre>
</small>
<h5><a name="7.20.5.1" href="#7.20.5.1">7.20.5.1 The bsearch function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- int (*compar)(const void *, const void *));</pre>
-<h6>Description</h6>
+ int (*compar)(const void *, const void *));
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void qsort(void *base, size_t nmemb, size_t size,
- int (*compar)(const void *, const void *));</pre>
-<h6>Description</h6>
+ int (*compar)(const void *, const void *));
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 5 -->
The qsort function returns no value.
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int abs(int j);
long int labs(long int j);
- long long int llabs(long long int j);</pre>
-<h6>Description</h6>
+ long long int llabs(long long int j);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The abs, labs, and llabs, functions return the absolute value.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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);
- lldiv_t lldiv(long long int numer, long long int denom);</pre>
-<h6>Description</h6>
+ lldiv_t lldiv(long long int numer, long long int denom);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The div, ldiv, and lldiv, functions compute numer / denom and numer %
denom in a single operation.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- int mblen(const char *s, size_t n);</pre>
-<h6>Description</h6>
+ int mblen(const char *s, size_t n);
+</pre>
+<p><b>Description</b>
<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 3 -->
<pre>
- mbtowc((wchar_t *)0, s, n);</pre>
+ mbtowc((wchar_t *)0, s, n);
+</pre>
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the mblen function.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 334 -->
<h5><a name="7.20.7.2" href="#7.20.7.2">7.20.7.2 The mbtowc function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int mbtowc(wchar_t * restrict pwc,
const char * restrict s,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
macro.
<h5><a name="7.20.7.3" href="#7.20.7.3">7.20.7.3 The wctomb function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
- int wctomb(char *s, wchar_t wc);</pre>
-<h6>Description</h6>
+ int wctomb(char *s, wchar_t wc);
+</pre>
+<p><b>Description</b>
<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
<!--page 335 -->
<p><!--para 3 -->
The implementation shall behave as if no library function calls the wctomb function.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
the current locale.
<h5><a name="7.20.8.1" href="#7.20.8.1">7.20.8.1 The mbstowcs function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 336 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t wcstombs(char * restrict s,
const wchar_t * restrict pwcs,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
returns the number of bytes modified, not including a terminating null character, if
- any.267)
+ any.<sup><a href="#note267"><b>267)</b></a></sup>
<!--page 337 -->
-<h3><a name="7.21" href="#7.21">7.21 String handling <string.h></a></h3>
+<h3><a name="7.21" href="#7.21">7.21 String handling <string.h></a></h3>
<h4><a name="7.21.1" href="#7.21.1">7.21.1 String function conventions</a></h4>
<p><!--para 1 -->
unsigned char (and therefore every possible object representation is valid and has a
different value).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memcpy(void * restrict s1,
const void * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The memcpy function returns the value of s1.
<!--page 338 -->
<h5><a name="7.21.2.2" href="#7.21.2.2">7.21.2.2 The memmove function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- void *memmove(void *s1, const void *s2, size_t n);</pre>
-<h6>Description</h6>
+ void *memmove(void *s1, const void *s2, size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcpy(char * restrict s1,
- const char * restrict s2);</pre>
-<h6>Description</h6>
+ const char * restrict s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncpy(char * restrict s1,
const char * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 4 -->
The strncpy function returns the value of s1.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcat(char * restrict s1,
- const char * restrict s2);</pre>
-<h6>Description</h6>
+ const char * restrict s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncat(char * restrict s1,
const char * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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
<!--page 340 -->
takes place between objects that overlap, the behavior is undefined.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note270" href="#note270">270)</a> Thus, the maximum number of characters that can end up in the array pointed to by s1 is
strlen(s1)+n+1.
</small>
compared.
<h5><a name="7.21.4.1" href="#7.21.4.1">7.21.4.1 The memcmp function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- int memcmp(const void *s1, const void *s2, size_t n);</pre>
-<h6>Description</h6>
+ int memcmp(const void *s1, const void *s2, size_t n);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- int strcmp(const char *s1, const char *s2);</pre>
-<h6>Description</h6>
+ int strcmp(const char *s1, const char *s2);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The strcmp function compares the string pointed to by s1 to the string pointed to by
s2.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
pointed to by s2.
<h5><a name="7.21.4.3" href="#7.21.4.3">7.21.4.3 The strcoll function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- int strcoll(const char *s1, const char *s2);</pre>
-<h6>Description</h6>
+ int strcoll(const char *s1, const char *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- int strncmp(const char *s1, const char *s2, size_t n);</pre>
-<h6>Description</h6>
+ int strncmp(const char *s1, const char *s2, size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strxfrm(char * restrict s1,
const char * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
- 1 + strxfrm(NULL, s, 0)</pre>
+ 1 + strxfrm(NULL, s, 0)
+</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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- void *memchr(const void *s, int c, size_t n);</pre>
-<h6>Description</h6>
+ void *memchr(const void *s, int c, size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- char *strchr(const char *s, int c);</pre>
-<h6>Description</h6>
+ char *strchr(const char *s, int c);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- size_t strcspn(const char *s1, const char *s2);</pre>
-<h6>Description</h6>
+ size_t strcspn(const char *s1, const char *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- char *strpbrk(const char *s1, const char *s2);</pre>
-<h6>Description</h6>
+ char *strpbrk(const char *s1, const char *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- char *strrchr(const char *s, int c);</pre>
-<h6>Description</h6>
+ char *strrchr(const char *s, int c);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- size_t strspn(const char *s1, const char *s2);</pre>
-<h6>Description</h6>
+ size_t strspn(const char *s1, const char *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- char *strstr(const char *s1, const char *s2);</pre>
-<h6>Description</h6>
+ char *strstr(const char *s1, const char *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strtok(char * restrict s1,
- const char * restrict s2);</pre>
-<h6>Description</h6>
+ const char * restrict s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 7 -->
The strtok function returns a pointer to the first character of a token, or a null pointer
if there is no token.
t = strtok(str, "?"); // t points to the token "a"
t = strtok(NULL, ","); // t points to the token "??b"
t = strtok(NULL, "#,"); // t points to the token "c"
- t = strtok(NULL, "?"); // t is a null pointer</pre>
+ t = strtok(NULL, "?"); // t is a null pointer
+</pre>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- void *memset(void *s, int c, size_t n);</pre>
-<h6>Description</h6>
+ void *memset(void *s, int c, size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- char *strerror(int errnum);</pre>
-<h6>Description</h6>
+ char *strerror(int errnum);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
- size_t strlen(const char *s);</pre>
-<h6>Description</h6>
+ size_t strlen(const char *s);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The strlen function computes the length of the string pointed to by s.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The strlen function returns the number of characters that precede the terminating null
character.
<!--page 347 -->
-<h3><a name="7.22" href="#7.22">7.22 Type-generic math <tgmath.h></a></h3>
+<h3><a name="7.22" href="#7.22">7.22 Type-generic math <tgmath.h></a></h3>
<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.
<pre>
<a href="#7.12"><math.h></a> <a href="#7.3"><complex.h></a> type-generic
function function macro
+
acos cacos acos
asin casin asin
atan catan atan
log clog log
pow cpow pow
sqrt csqrt sqrt
- fabs cabs fabs</pre>
+ fabs cabs fabs
+</pre>
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 -->
exp2 ilogb lround tgamma
expm1 ldexp nearbyint trunc
fdim lgamma nextafter
- floor llrint nexttoward</pre>
+ floor llrint nexttoward
+</pre>
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 -->
<!--page 349 -->
<pre>
carg conj creal
- cimag cproj</pre>
+ cimag cproj
+</pre>
Use of the macro with any real or complex argument invokes a complex function.
<p><!--para 7 -->
EXAMPLE With the declarations
long double ld;
float complex fc;
double complex dc;
- long double complex ldc;</pre>
+ long double complex ldc;
+</pre>
functions invoked by use of type-generic macros are shown in the following table:
<!--page 350 -->
<pre>
- macro use invokes
+ macro use invokes
+
exp(n) exp(n), the function
acosh(f) acoshf(f)
sin(d) sin(d), the function
cimag(ld) cimagl(ld)
fabs(fc) cabsf(fc)
carg(dc) carg(dc), the function
- cproj(ldc) cprojl(ldc)</pre>
+ cproj(ldc) cprojl(ldc)
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
the behavior is undefined.
</small>
-<h3><a name="7.23" href="#7.23">7.23 Date and time <time.h></a></h3>
+<h3><a name="7.23" href="#7.23">7.23 Date and time <time.h></a></h3>
<h4><a name="7.23.1" href="#7.23.1">7.23.1 Components of time</a></h4>
<p><!--para 1 -->
<p><!--para 2 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>); and
<pre>
- CLOCKS_PER_SEC</pre>
+ CLOCKS_PER_SEC
+</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>
- clock_t</pre>
+ clock_t
+</pre>
and
<pre>
- time_t</pre>
+ time_t
+</pre>
which are arithmetic types capable of representing times; and
<pre>
- struct tm</pre>
+ struct tm
+</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
int tm_year; // years since 1900
int tm_wday; // days since Sunday -- [0, 6]
int tm_yday; // days since January 1 -- [0, 365]
- int tm_isdst; // Daylight Saving Time flag</pre>
+ int tm_isdst; // Daylight Saving Time flag
+</pre>
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- clock_t clock(void);</pre>
-<h6>Description</h6>
+ clock_t clock(void);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The clock function determines the processor time used.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- double difftime(time_t time1, time_t time0);</pre>
-<h6>Description</h6>
+ double difftime(time_t time1, time_t time0);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The difftime function computes the difference between two calendar times: time1 -
time0.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The difftime function returns the difference expressed in seconds as a double.
<!--page 352 -->
<h5><a name="7.23.2.3" href="#7.23.2.3">7.23.2.3 The mktime function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- time_t mktime(struct tm *timeptr);</pre>
-<h6>Description</h6>
+ time_t mktime(struct tm *timeptr);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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;
- /* ... */</pre>
+ /* ... */
+</pre>
time_str.tm_isdst = -1;
if (mktime(&time_str) == (time_t)(-1))
time_str.tm_wday = 7;
- printf("%s\n", wday[time_str.tm_wday]);</pre>
+ printf("%s\n", wday[time_str.tm_wday]);
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- time_t time(time_t *timer);</pre>
-<h6>Description</h6>
+ time_t time(time_t *timer);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The time function determines the current calendar time. The encoding of the value is
unspecified.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- char *asctime(const struct tm *timeptr);</pre>
-<h6>Description</h6>
+ char *asctime(const struct tm *timeptr);
+</pre>
+<p><b>Description</b>
<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>
- Sun Sep 16 01:03:52 1973\n\0</pre>
+ Sun Sep 16 01:03:52 1973\n\0
+</pre>
using the equivalent of the following algorithm.
+<pre>
char *asctime(const struct tm *timeptr)
{
-<pre>
static const char wday_name[7][3] = {
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};
timeptr->tm_mday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec,
1900 + timeptr->tm_year);
- return result;</pre>
+ return result;
}
-<h6>Returns</h6>
+</pre>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- char *ctime(const time_t *timer);</pre>
-<h6>Description</h6>
+ char *ctime(const time_t *timer);
+</pre>
+<p><b>Description</b>
<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>
- asctime(localtime(timer))</pre>
-<h6>Returns</h6>
+ asctime(localtime(timer))
+</pre>
+<p><b>Returns</b>
<p><!--para 3 -->
The ctime function returns the pointer returned by the asctime function with that
broken-down time as argument.
<!--page 355 -->
<h5><a name="7.23.3.3" href="#7.23.3.3">7.23.3.3 The gmtime function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- struct tm *gmtime(const time_t *timer);</pre>
-<h6>Description</h6>
+ struct tm *gmtime(const time_t *timer);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The gmtime function converts the calendar time pointed to by timer into a broken-
down time, expressed as UTC.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
- struct tm *localtime(const time_t *timer);</pre>
-<h6>Description</h6>
+ struct tm *localtime(const time_t *timer);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The localtime function converts the calendar time pointed to by timer into a
broken-down time, expressed as local time.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- const struct tm * restrict timeptr);</pre>
-<h6>Description</h6>
+ const struct tm * restrict timeptr);
+</pre>
+<p><b>Description</b>
<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,
of the current locale and by the values of zero or more members of the broken-down time
structure pointed to by timeptr, as specified in brackets in the description. If any of
the specified values is outside the normal range, the characters stored are unspecified.
- %a is replaced by the locale's abbreviated weekday name. [tm_wday]
- %A is replaced by the locale's full weekday name. [tm_wday]
- %b is replaced by the locale's abbreviated month name. [tm_mon]
- %B is replaced by the locale's full month name. [tm_mon]
- %c is replaced by the locale's appropriate date and time representation. [all specified
-<pre>
- in <a href="#7.23.1">7.23.1</a>]</pre>
- %C is replaced by the year divided by 100 and truncated to an integer, as a decimal
-<pre>
- number (00-99). [tm_year]</pre>
- %d is replaced by the day of the month as a decimal number (01-31). [tm_mday]
- %D is equivalent to ''%m/%d/%y''. [tm_mon, tm_mday, tm_year]
- %e is replaced by the day of the month as a decimal number (1-31); a single digit is
-<pre>
- preceded by a space. [tm_mday]</pre>
- %F is equivalent to ''%Y-%m-%d'' (the ISO 8601 date format). [tm_year, tm_mon,
-<pre>
- tm_mday]</pre>
- %g is replaced by the last 2 digits of the week-based year (see below) as a decimal
-<pre>
- number (00-99). [tm_year, tm_wday, tm_yday]</pre>
- %G is replaced by the week-based year (see below) as a decimal number (e.g., 1997).
-<pre>
- [tm_year, tm_wday, tm_yday]</pre>
- %h is equivalent to ''%b''. [tm_mon]
- %H is replaced by the hour (24-hour clock) as a decimal number (00-23). [tm_hour]
- %I is replaced by the hour (12-hour clock) as a decimal number (01-12). [tm_hour]
- %j is replaced by the day of the year as a decimal number (001-366). [tm_yday]
- %m is replaced by the month as a decimal number (01-12). [tm_mon]
- %M is replaced by the minute as a decimal number (00-59). [tm_min]
- %n is replaced by a new-line character.
- %p is replaced by the locale's equivalent of the AM/PM designations associated with a
-<pre>
- 12-hour clock. [tm_hour]</pre>
- %r is replaced by the locale's 12-hour clock time. [tm_hour, tm_min, tm_sec]
- %R is equivalent to ''%H:%M''. [tm_hour, tm_min]
- %S is replaced by the second as a decimal number (00-60). [tm_sec]
- %t is replaced by a horizontal-tab character.
- %T is equivalent to ''%H:%M:%S'' (the ISO 8601 time format). [tm_hour, tm_min,
+<dl>
+<dt> %a <dd> is replaced by the locale's abbreviated weekday name. [tm_wday]
+<dt> %A <dd> is replaced by the locale's full weekday name. [tm_wday]
+<dt> %b <dd> is replaced by the locale's abbreviated month name. [tm_mon]
+<dt> %B <dd> is replaced by the locale's full month name. [tm_mon]
+<dt> %c <dd> is replaced by the locale's appropriate date and time representation. [all specified
+ in <a href="#7.23.1">7.23.1</a>]
+<dt> %C <dd> is replaced by the year divided by 100 and truncated to an integer, as a decimal
+ number (00-99). [tm_year]
+<dt> %d <dd> is replaced by the day of the month as a decimal number (01-31). [tm_mday]
+<dt> %D <dd> is equivalent to ''%m/%d/%y''. [tm_mon, tm_mday, tm_year]
+<dt> %e <dd> is replaced by the day of the month as a decimal number (1-31); a single digit is
+ preceded by a space. [tm_mday]
+<dt> %F <dd> is equivalent to ''%Y-%m-%d'' (the ISO 8601 date format). [tm_year, tm_mon,
+ tm_mday]
+<dt> %g <dd> is replaced by the last 2 digits of the week-based year (see below) as a decimal
+ number (00-99). [tm_year, tm_wday, tm_yday]
+<dt> %G <dd> is replaced by the week-based year (see below) as a decimal number (e.g., 1997).
+ [tm_year, tm_wday, tm_yday]
+<dt> %h <dd> is equivalent to ''%b''. [tm_mon]
+<dt> %H <dd> is replaced by the hour (24-hour clock) as a decimal number (00-23). [tm_hour]
+<dt> %I <dd> is replaced by the hour (12-hour clock) as a decimal number (01-12). [tm_hour]
+<dt> %j <dd> is replaced by the day of the year as a decimal number (001-366). [tm_yday]
+<dt> %m <dd> is replaced by the month as a decimal number (01-12). [tm_mon]
+<dt> %M <dd> is replaced by the minute as a decimal number (00-59). [tm_min]
+<dt> %n <dd> is replaced by a new-line character.
+<dt> %p <dd> is replaced by the locale's equivalent of the AM/PM designations associated with a
+ 12-hour clock. [tm_hour]
+<dt> %r <dd> is replaced by the locale's 12-hour clock time. [tm_hour, tm_min, tm_sec]
+<dt> %R <dd> is equivalent to ''%H:%M''. [tm_hour, tm_min]
+<dt> %S <dd> is replaced by the second as a decimal number (00-60). [tm_sec]
+<dt> %t <dd> is replaced by a horizontal-tab character.
+<dt> %T <dd> is equivalent to ''%H:%M:%S'' (the ISO 8601 time format). [tm_hour, tm_min,
<!--page 357 -->
-<pre>
- tm_sec]</pre>
- %u is replaced by the ISO 8601 weekday as a decimal number (1-7), where Monday
-<pre>
- is 1. [tm_wday]</pre>
- %U is replaced by the week number of the year (the first Sunday as the first day of week
-<pre>
- 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]</pre>
- %V is replaced by the ISO 8601 week number (see below) as a decimal number
-<pre>
- (01-53). [tm_year, tm_wday, tm_yday]</pre>
- %w is replaced by the weekday as a decimal number (0-6), where Sunday is 0.
-<pre>
- [tm_wday]</pre>
- %W is replaced by the week number of the year (the first Monday as the first day of
-<pre>
- week 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]</pre>
- %x is replaced by the locale's appropriate date representation. [all specified in <a href="#7.23.1">7.23.1</a>]
- %X is replaced by the locale's appropriate time representation. [all specified in <a href="#7.23.1">7.23.1</a>]
- %y is replaced by the last 2 digits of the year as a decimal number (00-99).
-<pre>
- [tm_year]</pre>
- %Y is replaced by the year as a decimal number (e.g., 1997). [tm_year]
- %z is replaced by the offset from UTC in the ISO 8601 format ''-0430'' (meaning 4
-<pre>
+ tm_sec]
+<dt> %u <dd>is replaced by the ISO 8601 weekday as a decimal number (1-7), where Monday
+ is 1. [tm_wday]
+<dt> %U <dd> is replaced by the week number of the year (the first Sunday as the first day of week
+ 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]
+<dt> %V <dd> is replaced by the ISO 8601 week number (see below) as a decimal number
+ (01-53). [tm_year, tm_wday, tm_yday]
+<dt> %w <dd> is replaced by the weekday as a decimal number (0-6), where Sunday is 0.
+ [tm_wday]
+<dt> %W <dd> is replaced by the week number of the year (the first Monday as the first day of
+ week 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]
+<dt> %x <dd> is replaced by the locale's appropriate date representation. [all specified in <a href="#7.23.1">7.23.1</a>]
+<dt> %X <dd> is replaced by the locale's appropriate time representation. [all specified in <a href="#7.23.1">7.23.1</a>]
+<dt> %y <dd> is replaced by the last 2 digits of the year as a decimal number (00-99).
+ [tm_year]
+<dt> %Y <dd> is replaced by the year as a decimal number (e.g., 1997). [tm_year]
+<dt> %z <dd> is replaced by the offset from UTC in the ISO 8601 format ''-0430'' (meaning 4
hours 30 minutes behind UTC, west of Greenwich), or by no characters if no time
- zone is determinable. [tm_isdst]</pre>
- %Z is replaced by the locale's time zone name or abbreviation, or by no characters if no
-<pre>
- time zone is determinable. [tm_isdst]</pre>
- %% is replaced by %.
+ zone is determinable. [tm_isdst]
+<dt> %Z <dd> is replaced by the locale's time zone name or abbreviation, or by no characters if no
+ time zone is determinable. [tm_isdst]
+<dt> %% <dd> is replaced by %.
+</dl>
<p><!--para 4 -->
Some conversion specifiers can be modified by the inclusion of an E or O modifier
character to indicate an alternative format or specification. If the alternative format or
specification does not exist for the current locale, the modifier is ignored.
- %Ec is replaced by the locale's alternative date and time representation.
- %EC is replaced by the name of the base year (period) in the locale's alternative
-<pre>
- representation.</pre>
- %Ex is replaced by the locale's alternative date representation.
- %EX is replaced by the locale's alternative time representation.
- %Ey is replaced by the offset from %EC (year only) in the locale's alternative
-<pre>
- representation.</pre>
- %EY is replaced by the locale's full alternative year representation.
- %Od is replaced by the day of the month, using the locale's alternative numeric symbols
-<pre>
+<dl>
+<dt> %Ec <dd> is replaced by the locale's alternative date and time representation.
+<dt> %EC <dd>is replaced by the name of the base year (period) in the locale's alternative
+ representation.
+<dt> %Ex <dd>is replaced by the locale's alternative date representation.
+<dt> %EX <dd>is replaced by the locale's alternative time representation.
+<dt> %Ey <dd>is replaced by the offset from %EC (year only) in the locale's alternative
+ representation.
+<dt> %EY <dd>is replaced by the locale's full alternative year representation.
+<dt> %Od <dd>is replaced by the day of the month, using the locale's alternative numeric symbols
(filled as needed with leading zeros, or with leading spaces if there is no alternative
- symbol for zero).</pre>
- %Oe is replaced by the day of the month, using the locale's alternative numeric symbols
-<pre>
- (filled as needed with leading spaces).</pre>
- %OH is replaced by the hour (24-hour clock), using the locale's alternative numeric
+ symbol for zero).
+<dt> %Oe <dd>is replaced by the day of the month, using the locale's alternative numeric symbols
+ (filled as needed with leading spaces).
+<dt> %OH <dd>is replaced by the hour (24-hour clock), using the locale's alternative numeric
<!--page 358 -->
-<pre>
- symbols.</pre>
- %OI is replaced by the hour (12-hour clock), using the locale's alternative numeric
-<pre>
- symbols.</pre>
- %Om is replaced by the month, using the locale's alternative numeric symbols.
- %OM is replaced by the minutes, using the locale's alternative numeric symbols.
- %OS is replaced by the seconds, using the locale's alternative numeric symbols.
- %Ou is replaced by the ISO 8601 weekday as a number in the locale's alternative
-<pre>
- representation, where Monday is 1.</pre>
- %OU is replaced by the week number, using the locale's alternative numeric symbols.
- %OV is replaced by the ISO 8601 week number, using the locale's alternative numeric
-<pre>
- symbols.</pre>
- %Ow is replaced by the weekday as a number, using the locale's alternative numeric
-<pre>
- symbols.</pre>
- %OW is replaced by the week number of the year, using the locale's alternative numeric
-<pre>
- symbols.</pre>
- %Oy is replaced by the last 2 digits of the year, using the locale's alternative numeric
+ symbols.
+<dt> %OI <dd>is replaced by the hour (12-hour clock), using the locale's alternative numeric
+ symbols.
+<dt> %Om <dd>is replaced by the month, using the locale's alternative numeric symbols.
+<dt> %OM <dd>is replaced by the minutes, using the locale's alternative numeric symbols.
+<dt> %OS <dd>is replaced by the seconds, using the locale's alternative numeric symbols.
+<dt> %Ou <dd>is replaced by the ISO 8601 weekday as a number in the locale's alternative
+ representation, where Monday is 1.
+<dt> %OU <dd>is replaced by the week number, using the locale's alternative numeric symbols.
+<dt> %OV <dd>is replaced by the ISO 8601 week number, using the locale's alternative numeric
+ symbols.
+<dt> %Ow <dd>is replaced by the weekday as a number, using the locale's alternative numeric
+ symbols.
+<dt> %OW <dd>is replaced by the week number of the year, using the locale's alternative numeric
+ symbols.
+<dt> %Oy <dd>is replaced by the last 2 digits of the year, using the locale's alternative numeric
+ symbols.
+</dl>
<p><!--para 5 -->
-<pre>
- symbols.</pre>
%g, %G, and %V give values according to the ISO 8601 week-based year. In this system,
weeks begin on a Monday and week 1 of the year is the week that includes January 4th,
which is also the week that includes the first Thursday of the year, and is also the first
<p><!--para 7 -->
In the "C" locale, the E and O modifiers are ignored and the replacement strings for the
following specifiers are:
- %a the first three characters of %A.
- %A one of ''Sunday'', ''Monday'', ... , ''Saturday''.
- %b the first three characters of %B.
- %B one of ''January'', ''February'', ... , ''December''.
- %c equivalent to ''%a %b %e %T %Y''.
- %p one of ''AM'' or ''PM''.
- %r equivalent to ''%I:%M:%S %p''.
- %x equivalent to ''%m/%d/%y''.
- %X equivalent to %T.
- %Z implementation-defined.
+<dl>
+<dt> %a <dd> the first three characters of %A.
+<dt> %A <dd> one of ''Sunday'', ''Monday'', ... , ''Saturday''.
+<dt> %b <dd> the first three characters of %B.
+<dt> %B <dd> one of ''January'', ''February'', ... , ''December''.
+<dt> %c <dd> equivalent to ''%a %b %e %T %Y''.
+<dt> %p <dd> one of ''AM'' or ''PM''.
+<dt> %r <dd> equivalent to ''%I:%M:%S %p''.
+<dt> %x <dd> equivalent to ''%m/%d/%y''.
+<dt> %X <dd> equivalent to %T.
+<dt> %Z <dd> implementation-defined.
+</dl>
<!--page 359 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
zero is returned and the contents of the array are indeterminate.
<!--page 360 -->
-<h3><a name="7.24" href="#7.24">7.24 Extended multibyte and wide character utilities <wchar.h></a></h3>
+<h3><a name="7.24" href="#7.24">7.24 Extended multibyte and wide character utilities <wchar.h></a></h3>
<h4><a name="7.24.1" href="#7.24.1">7.24.1 Introduction</a></h4>
<p><!--para 1 -->
<p><!--para 2 -->
The types declared are wchar_t and size_t (both described in <a href="#7.17">7.17</a>);
<pre>
- mbstate_t</pre>
+ mbstate_t
+</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>
- wint_t</pre>
+ wint_t
+</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>
- struct tm</pre>
+ struct tm
+</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>
- WEOF</pre>
+ WEOF
+</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
subclause causes copying to take place between objects that overlap, the behavior is
undefined.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- const wchar_t * restrict format, ...);</pre>
-<h6>Description</h6>
+ const wchar_t * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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
precision were omitted.
<p><!--para 6 -->
The flag wide characters and their meanings are:
- - The result of the conversion is left-justified within the field. (It is right-justified if
-<pre>
- this flag is not specified.)</pre>
- + The result of a signed conversion always begins with a plus or minus sign. (It
-<pre>
+<dl>
+<dt> - <dd> The result of the conversion is left-justified within the field. (It is right-justified if
+ this flag is not specified.)
+<dt> + <dd> The result of a signed conversion always begins with a plus or minus sign. (It
begins with a sign only when a negative value is converted if this flag is not
- specified.)<sup><a href="#note282"><b>282)</b></a></sup></pre>
- space If the first wide character of a signed conversion is not a sign, or if a signed
-<pre>
+ specified.)<sup><a href="#note282"><b>282)</b></a></sup>
+<dt> space<dd> If the first wide character of a signed conversion is not a sign, or if a signed
conversion results in no wide characters, a space is prefixed to the result. If the
- space and + flags both appear, the space flag is ignored.</pre>
- # The result is converted to an ''alternative form''. For o conversion, it increases
-<pre>
+ space and + flags both appear, the space flag is ignored.
+<dt> # <dd> The result is converted to an ''alternative form''. For o conversion, it increases
the precision, if and only if necessary, to force the first digit of the result to be a
zero (if the value and precision are both 0, a single 0 is printed). For x (or X)
- conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,</pre>
+ conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,
<!--page 363 -->
-<pre>
and G conversions, the result of converting a floating-point number always
contains a decimal-point wide character, even if no digits follow it. (Normally, a
decimal-point wide character appears in the result of these conversions only if a
digit follows it.) For g and G conversions, trailing zeros are not removed from the
- result. For other conversions, the behavior is undefined.</pre>
- 0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-<p><!--para 7 -->
-<pre>
+ result. For other conversions, the behavior is undefined.
+<dt> 0 <dd> For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
(following any indication of sign or base) are used to pad to the field width rather
than performing space padding, except when converting an infinity or NaN. If the
0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X
conversions, if a precision is specified, the 0 flag is ignored. For other
- conversions, the behavior is undefined.</pre>
+ conversions, the behavior is undefined.
+</dl>
+<p><!--para 7 -->
The length modifiers and their meanings are:
- hh Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+<dl>
+<dt> hh <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
signed char or unsigned char argument (the argument will have
been promoted according to the integer promotions, but its value shall be
converted to signed char or unsigned char before printing); or that
a following n conversion specifier applies to a pointer to a signed char
- argument.</pre>
- h Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ argument.
+<dt> h <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
short int or unsigned short int argument (the argument will
have been promoted according to the integer promotions, but its value shall
be converted to short int or unsigned short int before printing);
or that a following n conversion specifier applies to a pointer to a short
- int argument.</pre>
- l (ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ int argument.
+<dt> l (ell)<dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
long int or unsigned long int argument; that a following n
conversion specifier applies to a pointer to a long int argument; that a
following c conversion specifier applies to a wint_t argument; that a
following s conversion specifier applies to a pointer to a wchar_t
argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion
- specifier.</pre>
- ll (ell-ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ specifier.
+<dt> ll (ell-ell)<dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
long long int or unsigned long long int argument; or that a
following n conversion specifier applies to a pointer to a long long int
- argument.</pre>
- j Specifies that a following d, i, o, u, x, or X conversion specifier applies to
+ argument.
+<dt> j <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to
<!--page 364 -->
-<pre>
an intmax_t or uintmax_t argument; or that a following n conversion
- specifier applies to a pointer to an intmax_t argument.</pre>
- z Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ specifier applies to a pointer to an intmax_t argument.
+<dt> z <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
size_t or the corresponding signed integer type argument; or that a
following n conversion specifier applies to a pointer to a signed integer type
- corresponding to size_t argument.</pre>
- t Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<pre>
+ corresponding to size_t argument.
+<dt> t <dd> Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
ptrdiff_t or the corresponding unsigned integer type argument; or that a
following n conversion specifier applies to a pointer to a ptrdiff_t
- argument.</pre>
- L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-<pre>
- applies to a long double argument.</pre>
+ argument.
+<dt> L <dd> Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
+ applies to a long double argument.
+</dl>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
<p><!--para 8 -->
The conversion specifiers and their meanings are:
- d,i The int argument is converted to signed decimal in the style [-]dddd. The
-<pre>
+<dl>
+<dt> d,i <dd> The int argument is converted to signed decimal in the style [-]dddd. The
precision specifies the minimum number of digits to appear; if the value
being converted can be represented in fewer digits, it is expanded with
leading zeros. The default precision is 1. The result of converting a zero
- value with a precision of zero is no wide characters.</pre>
- o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned
-<pre>
+ value with a precision of zero is no wide characters.
+<dt> o,u,x,X<dd> The unsigned int argument is converted to unsigned octal (o), unsigned
decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the
letters abcdef are used for x conversion and the letters ABCDEF for X
conversion. The precision specifies the minimum number of digits to appear;
if the value being converted can be represented in fewer digits, it is expanded
with leading zeros. The default precision is 1. The result of converting a
- zero value with a precision of zero is no wide characters.</pre>
- f,F A double argument representing a floating-point number is converted to
+ zero value with a precision of zero is no wide characters.
+<dt> f,F <dd> A double argument representing a floating-point number is converted to
<!--page 365 -->
-<pre>
decimal notation in the style [-]ddd.ddd, where the number of digits after
the decimal-point wide character is equal to the precision specification. If the
precision is missing, it is taken as 6; if the precision is zero and the # flag is
[-]nan or [-]nan(n-wchar-sequence) -- which style, and the meaning of
any n-wchar-sequence, is implementation-defined. The F conversion
specifier produces INF, INFINITY, or NAN instead of inf, infinity, or
- nan, respectively.<sup><a href="#note283"><b>283)</b></a></sup></pre>
- e,E A double argument representing a floating-point number is converted in the
-<pre>
+ nan, respectively.<sup><a href="#note283"><b>283)</b></a></sup>
+<dt> e,E <dd> A double argument representing a floating-point number is converted in the
style [-]d.ddd e(+-)dd, where there is one digit (which is nonzero if the
argument is nonzero) before the decimal-point wide character and the number
of digits after it is equal to the precision; if the precision is missing, it is taken
and only as many more digits as necessary to represent the exponent. If the
value is zero, the exponent is zero.
A double argument representing an infinity or NaN is converted in the style
- of an f or F conversion specifier.</pre>
- g,G A double argument representing a floating-point number is converted in
-<pre>
+ of an f or F conversion specifier.
+<dt> g,G <dd> A double argument representing a floating-point number is converted in
style f or e (or in style F or E in the case of a G conversion specifier),
depending on the value converted and the precision. Let P equal the
precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero.
Then, if a conversion with style E would have an exponent of X :
- -- if P > X >= -4, the conversion is with style f (or F) and precision
+ <ul>
+ <li> if P > X >= -4, the conversion is with style f (or F) and precision
P - (X + 1).
- -- otherwise, the conversion is with style e (or E) and precision P - 1.
+ <li> otherwise, the conversion is with style e (or E) and precision P - 1.
+ </ul>
Finally, unless the # flag is used, any trailing zeros are removed from the
fractional portion of the result and the decimal-point wide character is
removed if there is no fractional portion remaining.
A double argument representing an infinity or NaN is converted in the style
- of an f or F conversion specifier.</pre>
- a,A A double argument representing a floating-point number is converted in the
-<pre>
+ of an f or F conversion specifier.
+<dt> a,A <dd> A double argument representing a floating-point number is converted in the
style [-]0xh.hhhh p(+-)d, where there is one hexadecimal digit (which is
nonzero if the argument is a normalized floating-point number and is
otherwise unspecified) before the decimal-point wide character<sup><a href="#note284"><b>284)</b></a></sup> and the
number of hexadecimal digits after it is equal to the precision; if the precision
- is missing and FLT_RADIX is a power of 2, then the precision is sufficient</pre>
-
-
+ is missing and FLT_RADIX is a power of 2, then the precision is sufficient
<!--page 366 -->
-<pre>
for an exact representation of the value; if the precision is missing and
FLT_RADIX is not a power of 2, then the precision is sufficient to
distinguish<sup><a href="#note285"><b>285)</b></a></sup> values of type double, except that trailing zeros may be
represent the decimal exponent of 2. If the value is zero, the exponent is
zero.
A double argument representing an infinity or NaN is converted in the style
- of an f or F conversion specifier.</pre>
- c If no l length modifier is present, the int argument is converted to a wide
-<pre>
+ of an f or F conversion specifier.
+<dt> c <dd> If no l length modifier is present, the int argument is converted to a wide
character as if by calling btowc and the resulting wide character is written.
If an l length modifier is present, the wint_t argument is converted to
- wchar_t and written.</pre>
- s If no l length modifier is present, the argument shall be a pointer to the initial
-<pre>
+ wchar_t and written.
+<dt> s <dd> If no l length modifier is present, the argument shall be a pointer to the initial
element of a character array containing a multibyte character sequence
beginning in the initial shift state. Characters from the array are converted as
if by repeated calls to the mbrtowc function, with the conversion state
written up to (but not including) a terminating null wide character. If the
precision is specified, no more than that many wide characters are written. If
the precision is not specified or is greater than the size of the array, the array
- shall contain a null wide character.</pre>
- p The argument shall be a pointer to void. The value of the pointer is
-<pre>
- converted to a sequence of printing wide characters, in an implementation-</pre>
-
+ shall contain a null wide character.
+<dt> p <dd> The argument shall be a pointer to void. The value of the pointer is
+ converted to a sequence of printing wide characters, in an implementation-
<!--page 367 -->
-<pre>
- defined manner.</pre>
- n The argument shall be a pointer to signed integer into which is written the
-<pre>
+ defined manner.
+<dt> n <dd> The argument shall be a pointer to signed integer into which is written the
number of wide characters written to the output stream so far by this call to
fwprintf. No argument is converted, but one is consumed. If the
conversion specification includes any flags, a field width, or a precision, the
- behavior is undefined.</pre>
- % A % wide character is written. No argument is converted. The complete
+ behavior is undefined.
+<dt> % <dd> A % wide character is written. No argument is converted. The complete
+ conversion specification shall be %%.
+</dl>
<p><!--para 9 -->
-<pre>
- conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note286"><b>286)</b></a></sup> If any argument is
not the correct type for the corresponding conversion specification, the behavior is
undefined.
<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.
- Recommended practice
+<p><b>Recommended practice</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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 -->
- Environmental limits
+<p><b>Environmental limits</b>
<p><!--para 15 -->
The number of wide characters that can be produced by any single conversion shall be at
least 4095.
int day, hour, min;
fwprintf(stdout, L"%ls, %ls %d, %.2d:%.2d\n",
weekday, month, day, hour, min);
- fwprintf(stdout, L"pi = %.5f\n", 4 * atan(1.0));</pre>
+ fwprintf(stdout, L"pi = %.5f\n", 4 * atan(1.0));
+</pre>
<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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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="note284" href="#note284">284)</a> Binary implementations can choose the hexadecimal digit to the left of the decimal-point wide
character so that subsequent digits align to nibble (4-bit) boundaries.
</small>
-<p><small><a name="note285" href="#note285">285)</a> The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
+<p><small><a name="note285" href="#note285">285)</a> The precision p is sufficient to distinguish values of the source type if 16<sup>p-1</sup> > b n where b is
FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p
might suffice depending on the implementation's scheme for determining the digit to the left of the
decimal-point wide character.
</small>
<h5><a name="7.24.2.2" href="#7.24.2.2">7.24.2.2 The fwscanf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- const wchar_t * restrict format, ...);</pre>
-<h6>Description</h6>
+ const wchar_t * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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
represented in the object, the behavior is undefined.
<p><!--para 11 -->
The length modifiers and their meanings are:
- hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
- to an argument with type pointer to signed char or unsigned char.</pre>
- h Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+<dl>
+<dt> hh <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
+ to an argument with type pointer to signed char or unsigned char.
+<dt> h <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to short int or unsigned short
- int.</pre>
- l (ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ int.
+<dt> l (ell) <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to long int or unsigned long
int; that a following a, A, e, E, f, F, g, or G conversion specifier applies to
an argument with type pointer to double; or that a following c, s, or [
- conversion specifier applies to an argument with type pointer to wchar_t.</pre>
- ll (ell-ell) Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ conversion specifier applies to an argument with type pointer to wchar_t.
+<dt> ll (ell-ell)<dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to long long int or unsigned
- long long int.</pre>
- j Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
- to an argument with type pointer to intmax_t or uintmax_t.</pre>
- z Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ long long int.
+<dt> j <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
+ to an argument with type pointer to intmax_t or uintmax_t.
+<dt> z <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to size_t or the corresponding signed
- integer type.</pre>
- t Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
-<pre>
+ integer type.
+<dt> t <dd> Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
to an argument with type pointer to ptrdiff_t or the corresponding
- unsigned integer type.</pre>
- L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
-<pre>
- applies to an argument with type pointer to long double.</pre>
+ unsigned integer type.
+<dt> L <dd> Specifies that a following a, A, e, E, f, F, g, or G conversion specifier
+ applies to an argument with type pointer to long double.
+</dl>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
<p><!--para 12 -->
The conversion specifiers and their meanings are:
- d Matches an optionally signed decimal integer, whose format is the same as
-<pre>
+<dl>
+<dt> d <dd> Matches an optionally signed decimal integer, whose format is the same as
expected for the subject sequence of the wcstol function with the value 10
for the base argument. The corresponding argument shall be a pointer to
- signed integer.</pre>
- i Matches an optionally signed integer, whose format is the same as expected
+ signed integer.
+<dt> i <dd> Matches an optionally signed integer, whose format is the same as expected
<!--page 371 -->
-<pre>
for the subject sequence of the wcstol function with the value 0 for the
base argument. The corresponding argument shall be a pointer to signed
- integer.</pre>
- o Matches an optionally signed octal integer, whose format is the same as
-<pre>
+ integer.
+<dt> o <dd> Matches an optionally signed octal integer, whose format is the same as
expected for the subject sequence of the wcstoul function with the value 8
for the base argument. The corresponding argument shall be a pointer to
- unsigned integer.</pre>
- u Matches an optionally signed decimal integer, whose format is the same as
-<pre>
+ unsigned integer.
+<dt> u <dd> Matches an optionally signed decimal integer, whose format is the same as
expected for the subject sequence of the wcstoul function with the value 10
for the base argument. The corresponding argument shall be a pointer to
- unsigned integer.</pre>
- x Matches an optionally signed hexadecimal integer, whose format is the same
-<pre>
+ unsigned integer.
+<dt> x <dd> Matches an optionally signed hexadecimal integer, whose format is the same
as expected for the subject sequence of the wcstoul function with the value
16 for the base argument. The corresponding argument shall be a pointer to
- unsigned integer.</pre>
- a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose
-<pre>
+ unsigned integer.
+<dt> a,e,f,g<dd> Matches an optionally signed floating-point number, infinity, or NaN, whose
format is the same as expected for the subject sequence of the wcstod
- function. The corresponding argument shall be a pointer to floating.</pre>
- c Matches a sequence of wide characters of exactly the number specified by the
-<pre>
+ function. The corresponding argument shall be a pointer to floating.
+<dt> c <dd> Matches a sequence of wide characters of exactly the number specified by the
field width (1 if no field width is present in the directive).
If no l length modifier is present, characters from the input field are
converted as if by repeated calls to the wcrtomb function, with the
accept the sequence. No null character is added.
If an l length modifier is present, the corresponding argument shall be a
pointer to the initial element of an array of wchar_t large enough to accept
- the sequence. No null wide character is added.</pre>
- s Matches a sequence of non-white-space wide characters.
+ the sequence. No null wide character is added.
+<dt> s <dd> Matches a sequence of non-white-space wide characters.
<!--page 372 -->
-<pre>
If no l length modifier is present, characters from the input field are
converted as if by repeated calls to the wcrtomb function, with the
conversion state described by an mbstate_t object initialized to zero
If an l length modifier is present, the corresponding argument shall be a
pointer to the initial element of an array of wchar_t large enough to accept
the sequence and the terminating null wide character, which will be added
- automatically.</pre>
- [ Matches a nonempty sequence of wide characters from a set of expected
-<pre>
+ automatically.
+<dt> [ <dd> Matches a nonempty sequence of wide characters from a set of expected
characters (the scanset).
If no l length modifier is present, characters from the input field are
converted as if by repeated calls to the wcrtomb function, with the
the specification; otherwise the first following right bracket wide character is
the one that ends the specification. If a - wide character is in the scanlist and
is not the first, nor the second where the first wide character is a ^, nor the
- last character, the behavior is implementation-defined.</pre>
- p Matches an implementation-defined set of sequences, which should be the
-<pre>
+ last character, the behavior is implementation-defined.
+<dt> p <dd> Matches an implementation-defined set of sequences, which should be the
same as the set of sequences that may be produced by the %p conversion of
the fwprintf function. The corresponding argument shall be a pointer to a
pointer to void. The input item is converted to a pointer value in an
implementation-defined manner. If the input item is a value converted earlier
during the same program execution, the pointer that results shall compare
- equal to that value; otherwise the behavior of the %p conversion is undefined.</pre>
- n No input is consumed. The corresponding argument shall be a pointer to
+ equal to that value; otherwise the behavior of the %p conversion is undefined.
+<dt> n <dd> No input is consumed. The corresponding argument shall be a pointer to
<!--page 373 -->
-<pre>
signed integer into which is to be written the number of wide characters read
from the input stream so far by this call to the fwscanf function. Execution
of a %n directive does not increment the assignment count returned at the
completion of execution of the fwscanf function. No argument is
converted, but one is consumed. If the conversion specification includes an
assignment-suppressing wide character or a field width, the behavior is
- undefined.</pre>
- % Matches a single % wide character; no conversion or assignment occurs. The
+ undefined.
+<dt> % <dd> Matches a single % wide character; no conversion or assignment occurs. The
+ complete conversion specification shall be %%.
+</dl>
<p><!--para 13 -->
-<pre>
- complete conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note290"><b>290)</b></a></sup>
<p><!--para 14 -->
The conversion specifiers A, E, F, G, and X are also valid and behave the same as,
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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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];
- n = fwscanf(stdin, L"%d%f%ls", &i, &x, name);</pre>
+ n = fwscanf(stdin, L"%d%f%ls", &i, &x, name);
+</pre>
with the input line:
<pre>
- 25 54.32E-1 thompson</pre>
+ 25 54.32E-1 thompson
+</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.
#include <a href="#7.24"><wchar.h></a>
/* ... */
int i; float x; double y;
- fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y);</pre>
+ fwscanf(stdin, L"%2d%f%*d %lf", &i, &x, &y);
+</pre>
with input:
<pre>
- 56789 0123 56a72</pre>
+ 56789 0123 56a72
+</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.
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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
</small>
<h5><a name="7.24.2.3" href="#7.24.2.3">7.24.2.3 The swprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swprintf(wchar_t * restrict s,
size_t n,
- const wchar_t * restrict format, ...);</pre>
-<h6>Description</h6>
+ const wchar_t * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swscanf(const wchar_t * restrict s,
- const wchar_t * restrict format, ...);</pre>
-<h6>Description</h6>
+ const wchar_t * restrict format, ...);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 375 -->
<h5><a name="7.24.2.5" href="#7.24.2.5">7.24.2.5 The vfwprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vfwprintf(FILE * restrict stream,
const wchar_t * restrict format,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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);
- }</pre>
+ }
+</pre>
<!--page 376 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vfwscanf(FILE * restrict stream,
const wchar_t * restrict format,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.291)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
+<p><b>Returns</b>
<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
early matching failure.
<h5><a name="7.24.2.7" href="#7.24.2.7">7.24.2.7 The vswprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
int vswprintf(wchar_t * restrict s,
size_t n,
const wchar_t * restrict format,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.291)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
+<p><b>Returns</b>
<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
<!--page 377 -->
<h5><a name="7.24.2.8" href="#7.24.2.8">7.24.2.8 The vswscanf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.291)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
+<p><b>Returns</b>
<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
early matching failure.
<h5><a name="7.24.2.9" href="#7.24.2.9">7.24.2.9 The vwprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.291)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- va_list arg);</pre>
-<h6>Description</h6>
+ va_list arg);
+</pre>
+<p><b>Description</b>
<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.291)
-<h6>Returns</h6>
+ va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
+<p><b>Returns</b>
<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
early matching failure.
<h5><a name="7.24.2.11" href="#7.24.2.11">7.24.2.11 The wprintf function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- int wprintf(const wchar_t * restrict format, ...);</pre>
-<h6>Description</h6>
+ int wprintf(const wchar_t * restrict format, ...);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The wprintf function is equivalent to fwprintf with the argument stdout
interposed before the arguments to wprintf.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- int wscanf(const wchar_t * restrict format, ...);</pre>
-<h6>Description</h6>
+ int wscanf(const wchar_t * restrict format, ...);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The wscanf function is equivalent to fwscanf with the argument stdin interposed
before the arguments to wscanf.
<!--page 379 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- wint_t fgetwc(FILE *stream);</pre>
-<h6>Description</h6>
+ wint_t fgetwc(FILE *stream);
+</pre>
+<p><b>Description</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- int n, FILE * restrict stream);</pre>
-<h6>Description</h6>
+ int n, FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- wint_t fputwc(wchar_t c, FILE *stream);</pre>
-<h6>Description</h6>
+ wint_t fputwc(wchar_t c, FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- FILE * restrict stream);</pre>
-<h6>Description</h6>
+ FILE * restrict stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- int fwide(FILE *stream, int mode);</pre>
-<h6>Description</h6>
+ int fwide(FILE *stream, int mode);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- wint_t getwc(FILE *stream);</pre>
-<h6>Description</h6>
+ wint_t getwc(FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wint_t getwchar(void);</pre>
+ wint_t getwchar(void);
+</pre>
<!--page 382 -->
-<h6>Description</h6>
+<p><b>Description</b>
<p><!--para 2 -->
The getwchar function is equivalent to getwc with the argument stdin.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- wint_t putwc(wchar_t c, FILE *stream);</pre>
-<h6>Description</h6>
+ wint_t putwc(wchar_t c, FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wint_t putwchar(wchar_t c);</pre>
-<h6>Description</h6>
+ wint_t putwchar(wchar_t c);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The putwchar function is equivalent to putwc with the second argument stdout.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- wint_t ungetwc(wint_t c, FILE *stream);</pre>
-<h6>Description</h6>
+ wint_t ungetwc(wint_t c, FILE *stream);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 6 -->
The ungetwc function returns the wide character pushed back, or WEOF if the operation
fails.
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
float wcstof(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);
long double wcstold(const wchar_t * restrict nptr,
- wchar_t ** restrict endptr);</pre>
-<h6>Description</h6>
+ wchar_t ** restrict endptr);
+</pre>
+<p><b>Description</b>
<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,
decimal-point wide character, then an optional binary exponent part as defined in
<a href="#6.4.4.2">6.4.4.2</a>;
<li> INF or INFINITY, or any other wide string equivalent except for case
-<li> NAN or NAN(n-wchar-sequenceopt), or any other wide string equivalent except for
+<li> NAN or NAN(n-wchar-sequence<sub>opt</sub>), or any other wide string equivalent except for
case in the NAN part, where:
<pre>
n-wchar-sequence:
digit
nondigit
n-wchar-sequence digit
- n-wchar-sequence nondigit</pre>
+ n-wchar-sequence nondigit
+</pre>
</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.
sign, the sequence is interpreted as negated.<sup><a href="#note294"><b>294)</b></a></sup> A wide character sequence INF or
INFINITY is interpreted as an infinity, if representable in the return type, else like a
floating constant that is too large for the range of the return type. A wide character
- sequence NAN or NAN(n-wchar-sequenceopt) is interpreted as a quiet NaN, if supported
+ sequence NAN or NAN(n-wchar-sequence<sub>opt</sub>) is interpreted as a quiet NaN, if supported
in the return type, else like a subject sequence part that does not have the expected form;
the meaning of the n-wchar sequences is implementation-defined.<sup><a href="#note295"><b>295)</b></a></sup> A pointer to the
final wide string is stored in the object pointed to by endptr, provided that endptr is
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
- Recommended practice
+<p><b>Recommended practice</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 387 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
unsigned long long int wcstoull(
const wchar_t * restrict nptr,
wchar_t ** restrict endptr,
- int base);</pre>
-<h6>Description</h6>
+ int base);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscpy(wchar_t * restrict s1,
- const wchar_t * restrict s2);</pre>
-<h6>Description</h6>
+ const wchar_t * restrict s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 4 -->
The wcsncpy function returns the value of s1.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemcpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The wmemcpy function copies n wide characters from the object pointed to by s2 to the
object pointed to by s1.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The wmemcpy function returns the value of s1.
<!--page 390 -->
<h5><a name="7.24.4.2.4" href="#7.24.4.2.4">7.24.4.2.4 The wmemmove function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscat(wchar_t * restrict s1,
- const wchar_t * restrict s2);</pre>
-<h6>Description</h6>
+ const wchar_t * restrict s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncat(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The wcsncat function returns the value of s1.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note298" href="#note298">298)</a> Thus, the maximum number of wide characters that can end up in the array pointed to by s1 is
wcslen(s1)+n+1.
</small>
by wchar_t.
<h5><a name="7.24.4.4.1" href="#7.24.4.4.1">7.24.4.4.1 The wcscmp function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- int wcscmp(const wchar_t *s1, const wchar_t *s2);</pre>
-<h6>Description</h6>
+ int wcscmp(const wchar_t *s1, const wchar_t *s2);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The wcscmp function compares the wide string pointed to by s1 to the wide string
pointed to by s2.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- int wcscoll(const wchar_t *s1, const wchar_t *s2);</pre>
-<h6>Description</h6>
+ int wcscoll(const wchar_t *s1, const wchar_t *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
locale.
<h5><a name="7.24.4.4.3" href="#7.24.4.4.3">7.24.4.4.3 The wcsncmp function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsxfrm(wchar_t * restrict s1,
const wchar_t * restrict s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
transformation of the wide string pointed to by s:
<!--page 393 -->
<pre>
- 1 + wcsxfrm(NULL, s, 0)</pre>
+ 1 + wcsxfrm(NULL, s, 0)
+</pre>
<h5><a name="7.24.4.4.5" href="#7.24.4.4.5">7.24.4.4.5 The wmemcmp function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wchar_t *wcschr(const wchar_t *s, wchar_t c);</pre>
-<h6>Description</h6>
+ wchar_t *wcschr(const wchar_t *s, wchar_t c);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- size_t wcscspn(const wchar_t *s1, const wchar_t *s2);</pre>
-<h6>Description</h6>
+ size_t wcscspn(const wchar_t *s1, const wchar_t *s2);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);</pre>
-<h6>Description</h6>
+ wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wchar_t *wcsrchr(const wchar_t *s, wchar_t c);</pre>
-<h6>Description</h6>
+ wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- size_t wcsspn(const wchar_t *s1, const wchar_t *s2);</pre>
-<h6>Description</h6>
+ size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);</pre>
-<h6>Description</h6>
+ wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcstok(wchar_t * restrict s1,
const wchar_t * restrict s2,
- wchar_t ** restrict ptr);</pre>
-<h6>Description</h6>
+ wchar_t ** restrict ptr);
+</pre>
+<p><b>Description</b>
<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).
-<h6>Returns</h6>
+<p><b>Returns</b>
<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 is a null pointer</pre>
+ t = wcstok(NULL, L"?", &ptr1); // t is a null pointer
+</pre>
<h5><a name="7.24.4.5.8" href="#7.24.4.5.8">7.24.4.5.8 The wmemchr function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
- size_t n);</pre>
-<h6>Description</h6>
+ size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- size_t wcslen(const wchar_t *s);</pre>
-<h6>Description</h6>
+ size_t wcslen(const wchar_t *s);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The wcslen function computes the length of the wide string pointed to by s.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);</pre>
-<h6>Description</h6>
+ wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
size_t wcsftime(wchar_t * restrict s,
size_t maxsize,
const wchar_t * restrict format,
- const struct tm * restrict timeptr);</pre>
-<h6>Description</h6>
+ const struct tm * restrict timeptr);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The wcsftime function is equivalent to the strftime function, except that:
<ul>
corresponding sequences of wide characters.
<li> The return value indicates the number of wide characters.
</ul>
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 399 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- wint_t btowc(int c);</pre>
-<h6>Description</h6>
+ wint_t btowc(int c);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The btowc function determines whether c constitutes a valid single-byte character in the
initial shift state.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
- int wctob(wint_t c);</pre>
-<h6>Description</h6>
+ int wctob(wint_t c);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
- int mbsinit(const mbstate_t *ps);</pre>
-<h6>Description</h6>
+ int mbsinit(const mbstate_t *ps);
+</pre>
+<p><b>Description</b>
<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 -->
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrlen(const char * restrict s,
size_t n,
- mbstate_t * restrict ps);</pre>
-<h6>Description</h6>
+ mbstate_t * restrict ps);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The mbrlen function is equivalent to the call:
<pre>
- 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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 3 -->
The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2),
or (size_t)(-1).
<!--page 401 -->
<h5><a name="7.24.6.3.2" href="#7.24.6.3.2">7.24.6.3.2 The mbrtowc function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- mbstate_t * restrict ps);</pre>
-<h6>Description</h6>
+ mbstate_t * restrict ps);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
If s is a null pointer, the mbrtowc function is equivalent to the call:
<pre>
- 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
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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<p><!--para 4 -->
The mbrtowc function returns the first of the following that applies (given the current
conversion state):
- 0 if the next n or fewer bytes complete the multibyte character that
-<pre>
- corresponds to the null wide character (which is the value stored).</pre>
- between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte
-<pre>
+<dl>
+<dt> 0 <dd> if the next n or fewer bytes complete the multibyte character that
+ corresponds to the null wide character (which is the value stored).
+<dt> between 1 and n inclusive<dd> if the next n or fewer bytes complete a valid multibyte
character (which is the value stored); the value returned is the number
- of bytes that complete the multibyte character.</pre>
- (size_t)(-2) if the next n bytes contribute to an incomplete (but potentially valid)
-<pre>
+ of bytes that complete the multibyte character.
+<dt> (size_t)(-2)<dd> if the next n bytes contribute to an incomplete (but potentially valid)
multibyte character, and all n bytes have been processed (no value is
- stored).<sup><a href="#note300"><b>300)</b></a></sup></pre>
- (size_t)(-1) if an encoding error occurs, in which case the next n or fewer bytes
-<pre>
+ stored).<sup><a href="#note300"><b>300)</b></a></sup>
+<dt> (size_t)(-1)<dd> if an encoding error occurs, in which case the next n or fewer bytes
do not contribute to a complete and valid multibyte character (no
value is stored); the value of the macro EILSEQ is stored in errno,
- and the conversion state is unspecified.</pre>
-
+ and the conversion state is unspecified.
+</dl>
<!--page 402 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcrtomb(char * restrict s,
wchar_t wc,
- mbstate_t * restrict ps);</pre>
-<h6>Description</h6>
+ mbstate_t * restrict ps);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
If s is a null pointer, the wcrtomb function is equivalent to the call
<pre>
- wcrtomb(buf, L'\0', ps)</pre>
+ wcrtomb(buf, L'\0', ps)
+</pre>
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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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:
<!--page 403 -->
<h5><a name="7.24.6.4.1" href="#7.24.6.4.1">7.24.6.4.1 The mbsrtowcs function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- mbstate_t * restrict ps);</pre>
-<h6>Description</h6>
+ mbstate_t * restrict ps);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 404 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<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,
- mbstate_t * restrict ps);</pre>
-<h6>Description</h6>
+ mbstate_t * restrict ps);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 405 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h3><a name="7.25" href="#7.25">7.25 Wide character classification and mapping utilities <wctype.h></a></h3>
+<h3><a name="7.25" href="#7.25">7.25 Wide character classification and mapping utilities <wctype.h></a></h3>
<h4><a name="7.25.1" href="#7.25.1">7.25.1 Introduction</a></h4>
<p><!--para 1 -->
<p><!--para 2 -->
The types declared are
<pre>
- wint_t</pre>
+ wint_t
+</pre>
described in <a href="#7.24.1">7.24.1</a>;
<pre>
- wctrans_t</pre>
+ wctrans_t
+</pre>
which is a scalar type that can hold values which represent locale-specific character
mappings; and
<pre>
- wctype_t</pre>
+ wctype_t
+</pre>
which is a scalar type that can hold values which represent locale-specific character
classifications.
<p><!--para 3 -->
<!--page 406 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note303" href="#note303">303)</a> See ''future library directions'' (<a href="#7.26.13">7.26.13</a>).
</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>).
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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)
</small>
<h5><a name="7.25.2.1.1" href="#7.25.2.1.1">7.25.2.1.1 The iswalnum function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswalnum(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswalnum(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswalpha(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswalpha(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswblank(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswblank(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswcntrl(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswcntrl(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswdigit(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswdigit(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswgraph(wint_t wc);</pre>
+ int iswgraph(wint_t wc);
+</pre>
<!--page 408 -->
-<h6>Description</h6>
+<p><b>Description</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswlower(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswlower(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswprint(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswprint(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswpunct(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswpunct(wint_t wc);
+</pre>
+<p><b>Description</b>
<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
- is true.306)
+ is true.<sup><a href="#note306"><b>306)</b></a></sup>
<h5><a name="7.25.2.1.10" href="#7.25.2.1.10">7.25.2.1.10 The iswspace function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswspace(wint_t wc);</pre>
+ int iswspace(wint_t wc);
+</pre>
<!--page 409 -->
-<h6>Description</h6>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswupper(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswupper(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswxdigit(wint_t wc);</pre>
-<h6>Description</h6>
+ int iswxdigit(wint_t wc);
+</pre>
+<p><b>Description</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- int iswctype(wint_t wc, wctype_t desc);</pre>
-<h6>Description</h6>
+ int iswctype(wint_t wc, wctype_t desc);
+</pre>
+<p><b>Description</b>
<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("xdigit")) // iswxdigit(wc)</pre>
-<h6>Returns</h6>
+ iswctype(wc, wctype("xdigit")) // iswxdigit(wc)
+</pre>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- wctype_t wctype(const char *property);</pre>
-<h6>Description</h6>
+ wctype_t wctype(const char *property);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- wint_t towlower(wint_t wc);</pre>
-<h6>Description</h6>
+ wint_t towlower(wint_t wc);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The towlower function converts an uppercase letter to a corresponding lowercase letter.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
returned unchanged.
<h5><a name="7.25.3.1.2" href="#7.25.3.1.2">7.25.3.1.2 The towupper function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- wint_t towupper(wint_t wc);</pre>
-<h6>Description</h6>
+ wint_t towupper(wint_t wc);
+</pre>
+<p><b>Description</b>
<p><!--para 2 -->
The towupper function converts a lowercase letter to a corresponding uppercase letter.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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
<!--page 412 -->
<h5><a name="7.25.3.2.1" href="#7.25.3.2.1">7.25.3.2.1 The towctrans function</a></h5>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- wint_t towctrans(wint_t wc, wctrans_t desc);</pre>
-<h6>Description</h6>
+ wint_t towctrans(wint_t wc, wctrans_t desc);
+</pre>
+<p><b>Description</b>
<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)
- towctrans(wc, wctrans("toupper")) // towupper(wc)</pre>
-<h6>Returns</h6>
+ towctrans(wc, wctrans("toupper")) // towupper(wc)
+</pre>
+<p><b>Returns</b>
<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>
-<h6>Synopsis</h6>
+<p><b>Synopsis</b>
<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
- wctrans_t wctrans(const char *property);</pre>
-<h6>Description</h6>
+ wctrans_t wctrans(const char *property);
+</pre>
+<p><b>Description</b>
<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.
-<h6>Returns</h6>
+<p><b>Returns</b>
<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.
-<h4><a name="7.26.1" href="#7.26.1">7.26.1 Complex arithmetic <complex.h></a></h4>
+<h4><a name="7.26.1" href="#7.26.1">7.26.1 Complex arithmetic <complex.h></a></h4>
<p><!--para 1 -->
The function names
<pre>
cerf cexpm1 clog2
cerfc clog10 clgamma
- cexp2 clog1p ctgamma</pre>
+ cexp2 clog1p ctgamma
+</pre>
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.
-<h4><a name="7.26.2" href="#7.26.2">7.26.2 Character handling <ctype.h></a></h4>
+<h4><a name="7.26.2" href="#7.26.2">7.26.2 Character handling <ctype.h></a></h4>
<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.
-<h4><a name="7.26.3" href="#7.26.3">7.26.3 Errors <errno.h></a></h4>
+<h4><a name="7.26.3" href="#7.26.3">7.26.3 Errors <errno.h></a></h4>
<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.
-<h4><a name="7.26.4" href="#7.26.4">7.26.4 Format conversion of integer types <inttypes.h></a></h4>
+<h4><a name="7.26.4" href="#7.26.4">7.26.4 Format conversion of integer types <inttypes.h></a></h4>
<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.
-<h4><a name="7.26.5" href="#7.26.5">7.26.5 Localization <locale.h></a></h4>
+<h4><a name="7.26.5" href="#7.26.5">7.26.5 Localization <locale.h></a></h4>
<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.
-<h4><a name="7.26.6" href="#7.26.6">7.26.6 Signal handling <signal.h></a></h4>
+<h4><a name="7.26.6" href="#7.26.6">7.26.6 Signal handling <signal.h></a></h4>
<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.
-<h4><a name="7.26.7" href="#7.26.7">7.26.7 Boolean type and values <stdbool.h></a></h4>
+<h4><a name="7.26.7" href="#7.26.7">7.26.7 Boolean type and values <stdbool.h></a></h4>
<p><!--para 1 -->
The ability to undefine and perhaps then redefine the macros bool, true, and false is
an obsolescent feature.
-<h4><a name="7.26.8" href="#7.26.8">7.26.8 Integer types <stdint.h></a></h4>
+<h4><a name="7.26.8" href="#7.26.8">7.26.8 Integer types <stdint.h></a></h4>
<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
<a href="#7.18"><stdint.h></a> header.
<!--page 414 -->
-<h4><a name="7.26.9" href="#7.26.9">7.26.9 Input/output <stdio.h></a></h4>
+<h4><a name="7.26.9" href="#7.26.9">7.26.9 Input/output <stdio.h></a></h4>
<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.
-<h4><a name="7.26.10" href="#7.26.10">7.26.10 General utilities <stdlib.h></a></h4>
+<h4><a name="7.26.10" href="#7.26.10">7.26.10 General utilities <stdlib.h></a></h4>
<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.
-<h4><a name="7.26.11" href="#7.26.11">7.26.11 String handling <string.h></a></h4>
+<h4><a name="7.26.11" href="#7.26.11">7.26.11 String handling <string.h></a></h4>
<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.
-<h4><a name="7.26.12" href="#7.26.12">7.26.12 Extended multibyte and wide character utilities <wchar.h></a></h4>
+<h4><a name="7.26.12" href="#7.26.12">7.26.12 Extended multibyte and wide character utilities <wchar.h></a></h4>
<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.
<!--page 415 -->
<h2><a name="A" href="#A">Annex A</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
- Language syntax summary</pre>
+ Language syntax summary
+</pre>
+<p><!--para 1 -->
NOTE The notation is described in <a href="#6.1">6.1</a>.
identifier
constant
string-literal
- punctuator</pre>
+ punctuator
+</pre>
(<a href="#6.4">6.4</a>) preprocessing-token:
<pre>
header-name
character-constant
string-literal
punctuator
- each non-white-space character that cannot be one of the above</pre>
+ each non-white-space character that cannot be one of the above
+</pre>
<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
default inline struct _Imaginary
do int switch
double long typedef
- else register union</pre>
+ else register union
+</pre>
<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
- identifier digit</pre>
+ identifier digit
+</pre>
(<a href="#6.4.2.1">6.4.2.1</a>) identifier-nondigit:
<pre>
nondigit
universal-character-name
- other implementation-defined characters</pre>
+ other implementation-defined characters
+</pre>
(<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
- N O P Q R S T U V W X Y Z</pre>
+ N O P Q R S T U V W X Y Z
+</pre>
(<a href="#6.4.2.1">6.4.2.1</a>) digit: one of
<pre>
- 0 1 2 3 4 5 6 7 8 9</pre>
+ 0 1 2 3 4 5 6 7 8 9
+</pre>
<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
- \U hex-quad hex-quad</pre>
+ \U hex-quad hex-quad
+</pre>
(<a href="#6.4.3">6.4.3</a>) hex-quad:
<pre>
hexadecimal-digit hexadecimal-digit
- hexadecimal-digit hexadecimal-digit</pre>
+ hexadecimal-digit hexadecimal-digit
+</pre>
<h4><a name="A.1.5" href="#A.1.5">A.1.5 Constants</a></h4>
(<a href="#6.4.4">6.4.4</a>) constant:
integer-constant
floating-constant
enumeration-constant
- character-constant</pre>
+ character-constant
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) integer-constant:
<pre>
- 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>
(<a href="#6.4.4.1">6.4.4.1</a>) decimal-constant:
<!--page 417 -->
<pre>
nonzero-digit
- decimal-constant digit</pre>
+ decimal-constant digit
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) octal-constant:
<pre>
0
- octal-constant octal-digit</pre>
+ octal-constant octal-digit
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) hexadecimal-constant:
<pre>
hexadecimal-prefix hexadecimal-digit
- hexadecimal-constant hexadecimal-digit</pre>
+ hexadecimal-constant hexadecimal-digit
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) hexadecimal-prefix: one of
<pre>
- 0x 0X</pre>
+ 0x 0X
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) nonzero-digit: one of
<pre>
- 1 2 3 4 5 6 7 8 9</pre>
+ 1 2 3 4 5 6 7 8 9
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) octal-digit: one of
<pre>
- 0 1 2 3 4 5 6 7</pre>
+ 0 1 2 3 4 5 6 7
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) hexadecimal-digit: one of
<pre>
0 1 2 3 4 5 6 7 8 9
a b c d e f
- A B C D E F</pre>
+ A B C D E F
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) integer-suffix:
<pre>
- unsigned-suffix long-suffixopt
+ unsigned-suffix long-suffix<sub>opt</sub>
unsigned-suffix long-long-suffix
- long-suffix unsigned-suffixopt
- long-long-suffix unsigned-suffixopt</pre>
+ long-suffix unsigned-suffix<sub>opt</sub>
+ long-long-suffix unsigned-suffix<sub>opt</sub>
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) unsigned-suffix: one of
<pre>
- u U</pre>
+ u U
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) long-suffix: one of
<pre>
- l L</pre>
+ l L
+</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) long-long-suffix: one of
<pre>
- ll LL</pre>
+ ll LL
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) floating-constant:
<pre>
decimal-floating-constant
- hexadecimal-floating-constant</pre>
+ hexadecimal-floating-constant
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) decimal-floating-constant:
<!--page 418 -->
<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
- binary-exponent-part floating-suffixopt
+ binary-exponent-part floating-suffix<sub>opt</sub>
hexadecimal-prefix hexadecimal-digit-sequence
- binary-exponent-part floating-suffixopt</pre>
+ binary-exponent-part floating-suffix<sub>opt</sub>
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) fractional-constant:
<pre>
- digit-sequenceopt . digit-sequence
- digit-sequence .</pre>
+ digit-sequence<sub>opt</sub> . digit-sequence
+ digit-sequence .
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) exponent-part:
<pre>
- e signopt digit-sequence
- E signopt digit-sequence</pre>
+ e sign<sub>opt</sub> digit-sequence
+ E sign<sub>opt</sub> digit-sequence
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) sign: one of
<pre>
- + -</pre>
+ + -
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) digit-sequence:
<pre>
digit
- digit-sequence digit</pre>
+ digit-sequence digit
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) hexadecimal-fractional-constant:
<pre>
- hexadecimal-digit-sequenceopt .
+ hexadecimal-digit-sequence<sub>opt</sub> .
hexadecimal-digit-sequence
- hexadecimal-digit-sequence .</pre>
+ hexadecimal-digit-sequence .
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) binary-exponent-part:
<pre>
- p signopt digit-sequence
- P signopt digit-sequence</pre>
+ p sign<sub>opt</sub> digit-sequence
+ P sign<sub>opt</sub> digit-sequence
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) hexadecimal-digit-sequence:
<pre>
hexadecimal-digit
- hexadecimal-digit-sequence hexadecimal-digit</pre>
+ hexadecimal-digit-sequence hexadecimal-digit
+</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) floating-suffix: one of
<pre>
- f l F L</pre>
+ f l F L
+</pre>
(<a href="#6.4.4.3">6.4.4.3</a>) enumeration-constant:
<pre>
- identifier</pre>
+ identifier
+</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) character-constant:
<!--page 419 -->
<pre>
' c-char-sequence '
- L' c-char-sequence '</pre>
+ L' c-char-sequence '
+</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) c-char-sequence:
<pre>
c-char
- c-char-sequence c-char</pre>
+ c-char-sequence c-char
+</pre>
(<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
- escape-sequence</pre>
+ escape-sequence
+</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) escape-sequence:
<pre>
simple-escape-sequence
octal-escape-sequence
hexadecimal-escape-sequence
- universal-character-name</pre>
+ universal-character-name
+</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) simple-escape-sequence: one of
<pre>
\' \" \? \\
- \a \b \f \n \r \t \v</pre>
+ \a \b \f \n \r \t \v
+</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) octal-escape-sequence:
<pre>
\ octal-digit
\ octal-digit octal-digit
- \ octal-digit octal-digit octal-digit</pre>
+ \ octal-digit octal-digit octal-digit
+</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) hexadecimal-escape-sequence:
<pre>
\x hexadecimal-digit
- hexadecimal-escape-sequence hexadecimal-digit</pre>
+ hexadecimal-escape-sequence hexadecimal-digit
+</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>
- " s-char-sequenceopt "
- L" s-char-sequenceopt "</pre>
+ " s-char-sequence<sub>opt</sub> "
+ L" s-char-sequence<sub>opt</sub> "
+</pre>
(<a href="#6.4.5">6.4.5</a>) s-char-sequence:
<pre>
s-char
- s-char-sequence s-char</pre>
+ s-char-sequence s-char
+</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
- escape-sequence</pre>
+ escape-sequence
+</pre>
<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
? : ; ...
= *= /= %= += -= <<= >>= &= ^= |=
, # ##
- <: :> <% %> %: %:%:</pre>
+ <: :> <% %> %: %:%:
+</pre>
<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 >
- " q-char-sequence "</pre>
+ " q-char-sequence "
+</pre>
(<a href="#6.4.7">6.4.7</a>) h-char-sequence:
<pre>
h-char
- h-char-sequence h-char</pre>
+ h-char-sequence h-char
+</pre>
(<a href="#6.4.7">6.4.7</a>) h-char:
<pre>
any member of the source character set except
- the new-line character and ></pre>
+ the new-line character and >
+</pre>
(<a href="#6.4.7">6.4.7</a>) q-char-sequence:
<pre>
q-char
- q-char-sequence q-char</pre>
+ q-char-sequence q-char
+</pre>
(<a href="#6.4.7">6.4.7</a>) q-char:
<pre>
any member of the source character set except
- the new-line character and "</pre>
+ the new-line character and "
+</pre>
<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:
pp-number E sign
pp-number p sign
pp-number P sign
- pp-number .</pre>
+ pp-number .
+</pre>
<h3><a name="A.2" href="#A.2">A.2 Phrase structure grammar</a></h3>
identifier
constant
string-literal
- ( expression )</pre>
+ ( expression )
+</pre>
(<a href="#6.5.2">6.5.2</a>) postfix-expression:
<pre>
primary-expression
postfix-expression [ expression ]
- postfix-expression ( argument-expression-listopt )
+ postfix-expression ( argument-expression-list<sub>opt</sub> )
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
- ( type-name ) { initializer-list , }</pre>
+ ( type-name ) { initializer-list , }
+</pre>
(<a href="#6.5.2">6.5.2</a>) argument-expression-list:
<pre>
assignment-expression
- argument-expression-list , assignment-expression</pre>
+ argument-expression-list , assignment-expression
+</pre>
(<a href="#6.5.3">6.5.3</a>) unary-expression:
<pre>
postfix-expression
-- unary-expression
unary-operator cast-expression
sizeof unary-expression
- sizeof ( type-name )</pre>
+ sizeof ( type-name )
+</pre>
(<a href="#6.5.3">6.5.3</a>) unary-operator: one of
<pre>
- & * + - ~ !</pre>
+ & * + - ~ !
+</pre>
(<a href="#6.5.4">6.5.4</a>) cast-expression:
<pre>
unary-expression
- ( type-name ) cast-expression</pre>
+ ( type-name ) cast-expression
+</pre>
(<a href="#6.5.5">6.5.5</a>) multiplicative-expression:
<!--page 422 -->
<pre>
cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
- multiplicative-expression % cast-expression</pre>
+ multiplicative-expression % cast-expression
+</pre>
(<a href="#6.5.6">6.5.6</a>) additive-expression:
<pre>
multiplicative-expression
additive-expression + multiplicative-expression
- additive-expression - multiplicative-expression</pre>
+ additive-expression - multiplicative-expression
+</pre>
(<a href="#6.5.7">6.5.7</a>) shift-expression:
<pre>
additive-expression
shift-expression << additive-expression
- shift-expression >> additive-expression</pre>
+ shift-expression >> additive-expression
+</pre>
(<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
- relational-expression >= shift-expression</pre>
+ relational-expression >= shift-expression
+</pre>
(<a href="#6.5.9">6.5.9</a>) equality-expression:
<pre>
relational-expression
equality-expression == relational-expression
- equality-expression != relational-expression</pre>
+ equality-expression != relational-expression
+</pre>
(<a href="#6.5.10">6.5.10</a>) AND-expression:
<pre>
equality-expression
- AND-expression & equality-expression</pre>
+ AND-expression & equality-expression
+</pre>
(<a href="#6.5.11">6.5.11</a>) exclusive-OR-expression:
<pre>
AND-expression
- exclusive-OR-expression ^ AND-expression</pre>
+ exclusive-OR-expression ^ AND-expression
+</pre>
(<a href="#6.5.12">6.5.12</a>) inclusive-OR-expression:
<pre>
exclusive-OR-expression
- inclusive-OR-expression | exclusive-OR-expression</pre>
+ inclusive-OR-expression | exclusive-OR-expression
+</pre>
(<a href="#6.5.13">6.5.13</a>) logical-AND-expression:
<pre>
inclusive-OR-expression
- logical-AND-expression && inclusive-OR-expression</pre>
+ logical-AND-expression && inclusive-OR-expression
+</pre>
(<a href="#6.5.14">6.5.14</a>) logical-OR-expression:
<pre>
logical-AND-expression
- logical-OR-expression || logical-AND-expression</pre>
+ logical-OR-expression || logical-AND-expression
+</pre>
(<a href="#6.5.15">6.5.15</a>) conditional-expression:
<!--page 423 -->
<pre>
logical-OR-expression
- logical-OR-expression ? expression : conditional-expression</pre>
+ logical-OR-expression ? expression : conditional-expression
+</pre>
(<a href="#6.5.16">6.5.16</a>) assignment-expression:
<pre>
conditional-expression
- unary-expression assignment-operator assignment-expression</pre>
+ unary-expression assignment-operator assignment-expression
+</pre>
(<a href="#6.5.16">6.5.16</a>) assignment-operator: one of
<pre>
- = *= /= %= += -= <<= >>= &= ^= |=</pre>
+ = *= /= %= += -= <<= >>= &= ^= |=
+</pre>
(<a href="#6.5.17">6.5.17</a>) expression:
<pre>
assignment-expression
- expression , assignment-expression</pre>
+ expression , assignment-expression
+</pre>
(<a href="#6.6">6.6</a>) constant-expression:
<pre>
- conditional-expression</pre>
+ conditional-expression
+</pre>
<h4><a name="A.2.2" href="#A.2.2">A.2.2 Declarations</a></h4>
(<a href="#6.7">6.7</a>) declaration:
<pre>
- declaration-specifiers init-declarator-listopt ;</pre>
+ declaration-specifiers init-declarator-list<sub>opt</sub> ;
+</pre>
(<a href="#6.7">6.7</a>) declaration-specifiers:
<pre>
- 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>
(<a href="#6.7">6.7</a>) init-declarator-list:
<pre>
init-declarator
- init-declarator-list , init-declarator</pre>
+ init-declarator-list , init-declarator
+</pre>
(<a href="#6.7">6.7</a>) init-declarator:
<pre>
declarator
- declarator = initializer</pre>
+ declarator = initializer
+</pre>
(<a href="#6.7.1">6.7.1</a>) storage-class-specifier:
<!--page 424 -->
<pre>
extern
static
auto
- register</pre>
+ register
+</pre>
(<a href="#6.7.2">6.7.2</a>) type-specifier:
<pre>
void
_Complex
struct-or-union-specifier *
enum-specifier
- typedef-name</pre>
+ typedef-name
+</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-or-union-specifier:
<pre>
- struct-or-union identifieropt { struct-declaration-list }
- struct-or-union identifier</pre>
+ struct-or-union identifier<sub>opt</sub> { struct-declaration-list }
+ struct-or-union identifier
+</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-or-union:
<pre>
struct
- union</pre>
+ union
+</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-declaration-list:
<pre>
struct-declaration
- struct-declaration-list struct-declaration</pre>
+ struct-declaration-list struct-declaration
+</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-declaration:
<pre>
- specifier-qualifier-list struct-declarator-list ;</pre>
+ specifier-qualifier-list struct-declarator-list ;
+</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) specifier-qualifier-list:
<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>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-declarator-list:
<pre>
struct-declarator
- struct-declarator-list , struct-declarator</pre>
+ struct-declarator-list , struct-declarator
+</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-declarator:
<!--page 425 -->
<pre>
declarator
- declaratoropt : constant-expression</pre>
+ declarator<sub>opt</sub> : constant-expression
+</pre>
(<a href="#6.7.2.2">6.7.2.2</a>) enum-specifier:
<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>
(<a href="#6.7.2.2">6.7.2.2</a>) enumerator-list:
<pre>
enumerator
- enumerator-list , enumerator</pre>
+ enumerator-list , enumerator
+</pre>
(<a href="#6.7.2.2">6.7.2.2</a>) enumerator:
<pre>
enumeration-constant
- enumeration-constant = constant-expression</pre>
+ enumeration-constant = constant-expression
+</pre>
(<a href="#6.7.3">6.7.3</a>) type-qualifier:
<pre>
const
restrict
- volatile</pre>
+ volatile
+</pre>
(<a href="#6.7.4">6.7.4</a>) function-specifier:
<pre>
- inline</pre>
+ inline
+</pre>
(<a href="#6.7.5">6.7.5</a>) declarator:
<pre>
- pointeropt direct-declarator</pre>
+ pointer<sub>opt</sub> direct-declarator
+</pre>
(<a href="#6.7.5">6.7.5</a>) direct-declarator:
<pre>
identifier
( declarator )
- 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-declarator [ type-qualifier-list static assignment-expression ]
- direct-declarator [ type-qualifier-listopt * ]
+ direct-declarator [ type-qualifier-list<sub>opt</sub> * ]
direct-declarator ( parameter-type-list )
- direct-declarator ( identifier-listopt )</pre>
+ direct-declarator ( identifier-list<sub>opt</sub> )
+</pre>
(<a href="#6.7.5">6.7.5</a>) pointer:
<pre>
- * type-qualifier-listopt
- * type-qualifier-listopt pointer</pre>
+ * type-qualifier-list<sub>opt</sub>
+ * type-qualifier-list<sub>opt</sub> pointer
+</pre>
(<a href="#6.7.5">6.7.5</a>) type-qualifier-list:
<pre>
type-qualifier
- type-qualifier-list type-qualifier</pre>
+ type-qualifier-list type-qualifier
+</pre>
(<a href="#6.7.5">6.7.5</a>) parameter-type-list:
<!--page 426 -->
<pre>
parameter-list
- parameter-list , ...</pre>
+ parameter-list , ...
+</pre>
(<a href="#6.7.5">6.7.5</a>) parameter-list:
<pre>
parameter-declaration
- parameter-list , parameter-declaration</pre>
+ parameter-list , parameter-declaration
+</pre>
(<a href="#6.7.5">6.7.5</a>) parameter-declaration:
<pre>
declaration-specifiers declarator
- declaration-specifiers abstract-declaratoropt</pre>
+ declaration-specifiers abstract-declarator<sub>opt</sub>
+</pre>
(<a href="#6.7.5">6.7.5</a>) identifier-list:
<pre>
identifier
- identifier-list , identifier</pre>
+ identifier-list , identifier
+</pre>
(<a href="#6.7.6">6.7.6</a>) type-name:
<pre>
- specifier-qualifier-list abstract-declaratoropt</pre>
+ specifier-qualifier-list abstract-declarator<sub>opt</sub>
+</pre>
(<a href="#6.7.6">6.7.6</a>) abstract-declarator:
<pre>
pointer
- pointeropt direct-abstract-declarator</pre>
+ pointer<sub>opt</sub> direct-abstract-declarator
+</pre>
(<a href="#6.7.6">6.7.6</a>) direct-abstract-declarator:
<pre>
( abstract-declarator )
- 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>
assignment-expression ]
- direct-abstract-declaratoropt [ type-qualifier-list static
+ direct-abstract-declarator<sub>opt</sub> [ type-qualifier-list static
assignment-expression ]
- 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>
(<a href="#6.7.7">6.7.7</a>) typedef-name:
<pre>
- identifier</pre>
+ identifier
+</pre>
(<a href="#6.7.8">6.7.8</a>) initializer:
<pre>
assignment-expression
{ initializer-list }
- { initializer-list , }</pre>
+ { initializer-list , }
+</pre>
(<a href="#6.7.8">6.7.8</a>) initializer-list:
<pre>
- designationopt initializer
- initializer-list , designationopt initializer</pre>
+ designation<sub>opt</sub> initializer
+ initializer-list , designation<sub>opt</sub> initializer
+</pre>
(<a href="#6.7.8">6.7.8</a>) designation:
<!--page 427 -->
<pre>
- designator-list =</pre>
+ designator-list =
+</pre>
(<a href="#6.7.8">6.7.8</a>) designator-list:
<pre>
designator
- designator-list designator</pre>
+ designator-list designator
+</pre>
(<a href="#6.7.8">6.7.8</a>) designator:
<pre>
[ constant-expression ]
- . identifier</pre>
+ . identifier
+</pre>
<h4><a name="A.2.3" href="#A.2.3">A.2.3 Statements</a></h4>
(<a href="#6.8">6.8</a>) statement:
expression-statement
selection-statement
iteration-statement
- jump-statement</pre>
+ jump-statement
+</pre>
(<a href="#6.8.1">6.8.1</a>) labeled-statement:
<pre>
identifier : statement
case constant-expression : statement
- default : statement</pre>
+ default : statement
+</pre>
(<a href="#6.8.2">6.8.2</a>) compound-statement:
<pre>
- { block-item-listopt }</pre>
+ { block-item-list<sub>opt</sub> }
+</pre>
(<a href="#6.8.2">6.8.2</a>) block-item-list:
<pre>
block-item
- block-item-list block-item</pre>
+ block-item-list block-item
+</pre>
(<a href="#6.8.2">6.8.2</a>) block-item:
<pre>
declaration
- statement</pre>
+ statement
+</pre>
(<a href="#6.8.3">6.8.3</a>) expression-statement:
<pre>
- expressionopt ;</pre>
+ expression<sub>opt</sub> ;
+</pre>
(<a href="#6.8.4">6.8.4</a>) selection-statement:
<!--page 428 -->
<pre>
if ( expression ) statement
if ( expression ) statement else statement
- switch ( expression ) statement</pre>
+ switch ( expression ) statement
+</pre>
(<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>
(<a href="#6.8.6">6.8.6</a>) jump-statement:
<pre>
goto identifier ;
continue ;
break ;
- return expressionopt ;</pre>
+ return expression<sub>opt</sub> ;
+</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
- translation-unit external-declaration</pre>
+ translation-unit external-declaration
+</pre>
(<a href="#6.9">6.9</a>) external-declaration:
<pre>
function-definition
- declaration</pre>
+ declaration
+</pre>
(<a href="#6.9.1">6.9.1</a>) function-definition:
<pre>
- declaration-specifiers declarator declaration-listopt compound-statement</pre>
+ declaration-specifiers declarator declaration-list<sub>opt</sub> compound-statement
+</pre>
(<a href="#6.9.1">6.9.1</a>) declaration-list:
<pre>
declaration
- declaration-list declaration</pre>
+ declaration-list declaration
+</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>
- groupopt</pre>
+ group<sub>opt</sub>
+</pre>
(<a href="#6.10">6.10</a>) group:
<pre>
group-part
- group group-part</pre>
+ group group-part
+</pre>
(<a href="#6.10">6.10</a>) group-part:
<pre>
if-section
control-line
text-line
- # non-directive</pre>
+ # non-directive
+</pre>
(<a href="#6.10">6.10</a>) if-section:
<!--page 429 -->
<pre>
- if-group elif-groupsopt else-groupopt endif-line</pre>
+ if-group elif-groups<sub>opt</sub> else-group<sub>opt</sub> endif-line
+</pre>
(<a href="#6.10">6.10</a>) if-group:
<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>) elif-groups:
<pre>
elif-group
- elif-groups elif-group</pre>
+ elif-groups elif-group
+</pre>
(<a href="#6.10">6.10</a>) elif-group:
<pre>
- # elif constant-expression new-line groupopt</pre>
+ # elif constant-expression new-line group<sub>opt</sub>
+</pre>
(<a href="#6.10">6.10</a>) else-group:
<pre>
- # else new-line groupopt</pre>
+ # else new-line group<sub>opt</sub>
+</pre>
(<a href="#6.10">6.10</a>) endif-line:
<pre>
- # endif new-line</pre>
+ # endif new-line
+</pre>
(<a href="#6.10">6.10</a>) control-line:
<pre>
# include pp-tokens new-line
# define identifier replacement-list new-line
- # define identifier lparen identifier-listopt )
+ # define identifier lparen identifier-list<sub>opt</sub> )
replacement-list new-line
# define identifier lparen ... ) replacement-list new-line
# define identifier lparen identifier-list , ... )
replacement-list new-line
# undef identifier new-line
# line pp-tokens new-line
- # error pp-tokensopt new-line
- # pragma pp-tokensopt new-line
- # new-line</pre>
+ # error pp-tokens<sub>opt</sub> new-line
+ # pragma pp-tokens<sub>opt</sub> new-line
+ # new-line
+</pre>
(<a href="#6.10">6.10</a>) text-line:
<pre>
- pp-tokensopt new-line</pre>
+ pp-tokens<sub>opt</sub> new-line
+</pre>
(<a href="#6.10">6.10</a>) non-directive:
<pre>
- pp-tokens new-line</pre>
+ pp-tokens new-line
+</pre>
(<a href="#6.10">6.10</a>) lparen:
<pre>
- a ( character not immediately preceded by white-space</pre>
+ a ( character not immediately preceded by white-space
+</pre>
(<a href="#6.10">6.10</a>) replacement-list:
<!--page 430 -->
<pre>
- pp-tokensopt</pre>
+ pp-tokens<sub>opt</sub>
+</pre>
(<a href="#6.10">6.10</a>) pp-tokens:
<pre>
preprocessing-token
- pp-tokens preprocessing-token</pre>
+ pp-tokens preprocessing-token
+</pre>
(<a href="#6.10">6.10</a>) new-line:
<!--page 431 -->
<pre>
- the new-line character</pre>
+ the new-line character
+</pre>
<h2><a name="B" href="#B">Annex B</a></h2>
<pre>
(informative)
- Library summary</pre>
+ Library summary
+</pre>
-<h3><a name="B.1" href="#B.1">B.1 Diagnostics <assert.h></a></h3>
+<h3><a name="B.1" href="#B.1">B.1 Diagnostics <assert.h></a></h3>
<pre>
NDEBUG
- void assert(scalar expression);</pre>
+ void assert(scalar expression);
+</pre>
-<h3><a name="B.2" href="#B.2">B.2 Complex <complex.h></a></h3>
+<h3><a name="B.2" href="#B.2">B.2 Complex <complex.h></a></h3>
<!--page 432 -->
<!--page 433 -->
<pre>
long double complex cprojl(long double complex z);
double creal(double complex z);
float crealf(float complex z);
- long double creall(long double complex z);</pre>
+ long double creall(long double complex z);
+</pre>
-<h3><a name="B.3" href="#B.3">B.3 Character handling <ctype.h></a></h3>
+<h3><a name="B.3" href="#B.3">B.3 Character handling <ctype.h></a></h3>
<pre>
int isalnum(int c);
int isalpha(int c);
int isupper(int c);
int isxdigit(int c);
int tolower(int c);
- int toupper(int c);</pre>
+ int toupper(int c);
+</pre>
-<h3><a name="B.4" href="#B.4">B.4 Errors <errno.h></a></h3>
+<h3><a name="B.4" href="#B.4">B.4 Errors <errno.h></a></h3>
<pre>
- EDOM EILSEQ ERANGE errno</pre>
+ EDOM EILSEQ ERANGE errno
+</pre>
-<h3><a name="B.5" href="#B.5">B.5 Floating-point environment <fenv.h></a></h3>
+<h3><a name="B.5" href="#B.5">B.5 Floating-point environment <fenv.h></a></h3>
<!--page 434 -->
<pre>
fenv_t FE_OVERFLOW FE_TOWARDZERO
int fegetenv(fenv_t *envp);
int feholdexcept(fenv_t *envp);
int fesetenv(const fenv_t *envp);
- int feupdateenv(const fenv_t *envp);</pre>
+ int feupdateenv(const fenv_t *envp);
+</pre>
-<h3><a name="B.6" href="#B.6">B.6 Characteristics of floating types <float.h></a></h3>
+<h3><a name="B.6" href="#B.6">B.6 Characteristics of floating types <float.h></a></h3>
<pre>
FLT_ROUNDS DBL_MIN_EXP FLT_MAX
FLT_EVAL_METHOD LDBL_MIN_EXP DBL_MAX
FLT_DIG LDBL_MAX_EXP DBL_MIN
DBL_DIG FLT_MAX_10_EXP LDBL_MIN
LDBL_DIG DBL_MAX_10_EXP
- FLT_MIN_EXP LDBL_MAX_10_EXP</pre>
+ FLT_MIN_EXP LDBL_MAX_10_EXP
+</pre>
-<h3><a name="B.7" href="#B.7">B.7 Format conversion of integer types <inttypes.h></a></h3>
+<h3><a name="B.7" href="#B.7">B.7 Format conversion of integer types <inttypes.h></a></h3>
<!--page 435 -->
<pre>
imaxdiv_t
intmax_t wcstoimax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);
uintmax_t wcstoumax(const wchar_t * restrict nptr,
- wchar_t ** restrict endptr, int base);</pre>
+ wchar_t ** restrict endptr, int base);
+</pre>
-<h3><a name="B.8" href="#B.8">B.8 Alternative spellings <iso646.h></a></h3>
+<h3><a name="B.8" href="#B.8">B.8 Alternative spellings <iso646.h></a></h3>
<pre>
and bitor not_eq xor
and_eq compl or xor_eq
- bitand not or_eq</pre>
+ bitand not or_eq
+</pre>
-<h3><a name="B.9" href="#B.9">B.9 Sizes of integer types <limits.h></a></h3>
+<h3><a name="B.9" href="#B.9">B.9 Sizes of integer types <limits.h></a></h3>
<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
- CHAR_MIN USHRT_MAX LONG_MAX</pre>
+ CHAR_MIN USHRT_MAX LONG_MAX
+</pre>
-<h3><a name="B.10" href="#B.10">B.10 Localization <locale.h></a></h3>
+<h3><a name="B.10" href="#B.10">B.10 Localization <locale.h></a></h3>
<pre>
struct lconv LC_ALL LC_CTYPE LC_NUMERIC
NULL LC_COLLATE LC_MONETARY LC_TIME
char *setlocale(int category, const char *locale);
- struct lconv *localeconv(void);</pre>
+ struct lconv *localeconv(void);
+</pre>
-<h3><a name="B.11" href="#B.11">B.11 Mathematics <math.h></a></h3>
+<h3><a name="B.11" href="#B.11">B.11 Mathematics <math.h></a></h3>
<!--page 436 -->
<!--page 437 -->
<!--page 438 -->
int isless(real-floating x, real-floating y);
int islessequal(real-floating x, real-floating y);
int islessgreater(real-floating x, real-floating y);
- int isunordered(real-floating x, real-floating y);</pre>
+ int isunordered(real-floating x, real-floating y);
+</pre>
-<h3><a name="B.12" href="#B.12">B.12 Nonlocal jumps <setjmp.h></a></h3>
+<h3><a name="B.12" href="#B.12">B.12 Nonlocal jumps <setjmp.h></a></h3>
<pre>
jmp_buf
int setjmp(jmp_buf env);
- void longjmp(jmp_buf env, int val);</pre>
+ void longjmp(jmp_buf env, int val);
+</pre>
-<h3><a name="B.13" href="#B.13">B.13 Signal handling <signal.h></a></h3>
+<h3><a name="B.13" href="#B.13">B.13 Signal handling <signal.h></a></h3>
<pre>
sig_atomic_t SIG_IGN SIGILL SIGTERM
SIG_DFL SIGABRT SIGINT
SIG_ERR SIGFPE SIGSEGV
void (*signal(int sig, void (*func)(int)))(int);
- int raise(int sig);</pre>
+ int raise(int sig);
+</pre>
-<h3><a name="B.14" href="#B.14">B.14 Variable arguments <stdarg.h></a></h3>
+<h3><a name="B.14" href="#B.14">B.14 Variable arguments <stdarg.h></a></h3>
<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);
- void va_start(va_list ap, parmN);</pre>
+ void va_start(va_list ap, parmN);
+</pre>
-<h3><a name="B.15" href="#B.15">B.15 Boolean type and values <stdbool.h></a></h3>
+<h3><a name="B.15" href="#B.15">B.15 Boolean type and values <stdbool.h></a></h3>
<!--page 441 -->
<pre>
bool
true
false
- __bool_true_false_are_defined</pre>
+ __bool_true_false_are_defined
+</pre>
-<h3><a name="B.16" href="#B.16">B.16 Common definitions <stddef.h></a></h3>
+<h3><a name="B.16" href="#B.16">B.16 Common definitions <stddef.h></a></h3>
<pre>
ptrdiff_t size_t wchar_t NULL
- offsetof(type, member-designator)</pre>
+ offsetof(type, member-designator)
+</pre>
-<h3><a name="B.17" href="#B.17">B.17 Integer types <stdint.h></a></h3>
+<h3><a name="B.17" href="#B.17">B.17 Integer types <stdint.h></a></h3>
<pre>
intN_t INT_LEASTN_MIN PTRDIFF_MAX
uintN_t INT_LEASTN_MAX SIG_ATOMIC_MIN
uintmax_t INTMAX_MIN UINTN_C(value)
INTN_MIN INTMAX_MAX INTMAX_C(value)
INTN_MAX UINTMAX_MAX UINTMAX_C(value)
- UINTN_MAX PTRDIFF_MIN</pre>
+ UINTN_MAX PTRDIFF_MIN
+</pre>
-<h3><a name="B.18" href="#B.18">B.18 Input/output <stdio.h></a></h3>
+<h3><a name="B.18" href="#B.18">B.18 Input/output <stdio.h></a></h3>
<!--page 442 -->
<!--page 443 -->
<pre>
void clearerr(FILE *stream);
int feof(FILE *stream);
int ferror(FILE *stream);
- void perror(const char *s);</pre>
+ void perror(const char *s);
+</pre>
-<h3><a name="B.19" href="#B.19">B.19 General utilities <stdlib.h></a></h3>
+<h3><a name="B.19" href="#B.19">B.19 General utilities <stdlib.h></a></h3>
<!--page 444 -->
<!--page 445 -->
<pre>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s, size_t n);
size_t wcstombs(char * restrict s,
- const wchar_t * restrict pwcs, size_t n);</pre>
+ const wchar_t * restrict pwcs, size_t n);
+</pre>
-<h3><a name="B.20" href="#B.20">B.20 String handling <string.h></a></h3>
+<h3><a name="B.20" href="#B.20">B.20 String handling <string.h></a></h3>
<!--page 446 -->
<pre>
size_t
const char * restrict s2);
void *memset(void *s, int c, size_t n);
char *strerror(int errnum);
- size_t strlen(const char *s);</pre>
+ size_t strlen(const char *s);
+</pre>
-<h3><a name="B.21" href="#B.21">B.21 Type-generic math <tgmath.h></a></h3>
+<h3><a name="B.21" href="#B.21">B.21 Type-generic math <tgmath.h></a></h3>
<pre>
acos sqrt fmod nextafter
asin fabs frexp nexttoward
tanh floor logb cimag
exp fma lrint conj
log fmax lround cproj
- pow fmin nearbyint creal</pre>
+ pow fmin nearbyint creal
+</pre>
-<h3><a name="B.22" href="#B.22">B.22 Date and time <time.h></a></h3>
+<h3><a name="B.22" href="#B.22">B.22 Date and time <time.h></a></h3>
<!--page 447 -->
<pre>
NULL size_t time_t
size_t strftime(char * restrict s,
size_t maxsize,
const char * restrict format,
- const struct tm * restrict timeptr);</pre>
+ const struct tm * restrict timeptr);
+</pre>
-<h3><a name="B.23" href="#B.23">B.23 Extended multibyte/wide character utilities <wchar.h></a></h3>
+<h3><a name="B.23" href="#B.23">B.23 Extended multibyte/wide character utilities <wchar.h></a></h3>
<!--page 448 -->
<!--page 449 -->
<pre>
mbstate_t * restrict ps);
size_t wcsrtombs(char * restrict dst,
const wchar_t ** restrict src, size_t len,
- mbstate_t * restrict ps);</pre>
+ mbstate_t * restrict ps);
+</pre>
-<h3><a name="B.24" href="#B.24">B.24 Wide character classification and mapping utilities <wctype.h></a></h3>
+<h3><a name="B.24" href="#B.24">B.24 Wide character classification and mapping utilities <wctype.h></a></h3>
<!--page 450 -->
<!--page 451 -->
<pre>
wint_t towlower(wint_t wc);
wint_t towupper(wint_t wc);
wint_t towctrans(wint_t wc, wctrans_t desc);
- wctrans_t wctrans(const char *property);</pre>
+ wctrans_t wctrans(const char *property);
+</pre>
<h2><a name="C" href="#C">Annex C</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
- Sequence points</pre>
+ Sequence points
+</pre>
+<p><!--para 1 -->
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>).
</ul>
<h2><a name="D" href="#D">Annex D</a></h2>
-<p><!--para 1 -->
<pre>
(normative)
- Universal character names for identifiers</pre>
+ Universal character names for identifiers
+</pre>
+<p><!--para 1 -->
This clause lists the hexadecimal code values that are valid in universal character names
in identifiers.
<p><!--para 2 -->
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,
- 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>
- 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>
- 05F0-05F2</pre>
+ 05F0-05F2
+</pre>
Arabic: 0621-063A, 0640-0652, 0670-06B7, 06BA-06BE, 06C0-06CE,
<pre>
- 06D0-06DC, 06E5-06E8, 06EA-06ED</pre>
+ 06D0-06DC, 06E5-06E8, 06EA-06ED
+</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,
- 09DC-09DD, 09DF-09E3, 09F0-09F1</pre>
+ 09DC-09DD, 09DF-09E3, 09F0-09F1
+</pre>
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,
- 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,
- 0B5C-0B5D, 0B5F-0B61</pre>
+ 0B5C-0B5D, 0B5F-0B61
+</pre>
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>
- 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,
- 0CE0-0CE1</pre>
+ 0CE0-0CE1
+</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,
- 0EC8-0ECD, 0EDC-0EDD</pre>
+ 0EC8-0ECD, 0EDC-0EDD
+</pre>
Tibetan: 0F00, 0F18-0F19, 0F35, 0F37, 0F39, 0F3E-0F47, 0F49-0F69,
<pre>
0F71-0F84, 0F86-0F8B, 0F90-0F95, 0F97, 0F99-0FAD,
- 0FB1-0FB7, 0FB9</pre>
+ 0FB1-0FB7, 0FB9
+</pre>
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,
- 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,
- 2133-2138, 2160-2182, 3005-3007, 3021-3029</pre>
+ 2133-2138, 2160-2182, 3005-3007, 3021-3029
+</pre>
<h2><a name="E" href="#E">Annex E</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
- Implementation limits</pre>
+ Implementation limits
+</pre>
+<p><!--para 1 -->
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>.
-<p><!--para 2 -->
<pre>
#define CHAR_BIT 8
#define CHAR_MAX UCHAR_MAX or SCHAR_MAX
#define USHRT_MAX 65535
#define UINT_MAX 65535
#define ULONG_MAX 4294967295
- #define ULLONG_MAX 18446744073709551615</pre>
+ #define ULLONG_MAX 18446744073709551615
+</pre>
+<p><!--para 2 -->
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
<p><!--para 3 -->
The values given in the following list shall be replaced by implementation-defined
expressions:
-<p><!--para 4 -->
<pre>
#define FLT_EVAL_METHOD
- #define FLT_ROUNDS</pre>
+ #define FLT_ROUNDS
+</pre>
+<p><!--para 4 -->
The values given in the following list shall be replaced by implementation-defined
constant expressions that are greater or equal in magnitude (absolute value) to those
shown, with the same sign:
<!--page 455 -->
-<p><!--para 5 -->
<pre>
#define DBL_DIG 10
#define DBL_MANT_DIG
#define LDBL_MAX_10_EXP +37
#define LDBL_MAX_EXP
#define LDBL_MIN_10_EXP -37
- #define LDBL_MIN_EXP</pre>
+ #define LDBL_MIN_EXP
+</pre>
+<p><!--para 5 -->
The values given in the following list shall be replaced by implementation-defined
constant expressions with values that are greater than or equal to those shown:
-<p><!--para 6 -->
<pre>
#define DBL_MAX 1E+37
#define FLT_MAX 1E+37
- #define LDBL_MAX 1E+37</pre>
+ #define LDBL_MAX 1E+37
+</pre>
+<p><!--para 6 -->
The values given in the following list shall be replaced by implementation-defined
constant expressions with (positive) values that are less than or equal to those shown:
<!--page 456 -->
#define FLT_EPSILON 1E-5
#define FLT_MIN 1E-37
#define LDBL_EPSILON 1E-9
- #define LDBL_MIN 1E-37</pre>
+ #define LDBL_MIN 1E-37
+</pre>
<h2><a name="F" href="#F">Annex F</a></h2>
<pre>
(normative)
- IEC 60559 floating-point arithmetic</pre>
+ IEC 60559 floating-point arithmetic
+</pre>
<h3><a name="F.1" href="#F.1">F.1 Introduction</a></h3>
<p><!--para 1 -->
</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>
- Recommended practice
+<p><b>Recommended practice</b>
<p><!--para 2 -->
The long double type should match an IEC 60559 extended format.
<!--page 457 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
<!--page 460 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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.
- Recommended practice
+<p><b>Recommended practice</b>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note312" href="#note312">312)</a> This specification does not require dynamic rounding precision nor trap enablement modes.
</small>
<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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
- Recommended practice
+<p><b>Recommended practice</b>
<p><!--para 2 -->
The implementation should produce a diagnostic message for each translation-time
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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
is ''on'').<sup><a href="#note315"><b>315)</b></a></sup>
<p><!--para 2 -->
EXAMPLE
-<p><!--para 3 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
float y = 0.0/0.0; // raises an exception
double z = 0.0/0.0; // raises an exception
/* ... */
- }</pre>
+ }
+</pre>
+<p><!--para 3 -->
For the static initialization, the division is done at translation time, raising no (execution-time) floating-
point exceptions. On the other hand, for the three automatic initializations the invalid division occurs at
execution time.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
- const static double one_third = 1.0/3.0;</pre>
+ const static double one_third = 1.0/3.0;
+</pre>
</small>
<h4><a name="F.7.5" href="#F.7.5">F.7.5 Initialization</a></h4>
time.
<p><!--para 2 -->
EXAMPLE
-<p><!--para 3 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
float y = 1.1e75f; // may raise exceptions
long double z = 1.1e75; // does not raise exceptions
/* ... */
- }</pre>
+ }
+</pre>
+<p><!--para 3 -->
The static initialization of v raises no (execution-time) floating-point exceptions because its computation is
done at translation time. The automatic initialization of u and w require an execution-time conversion to
float of the wider value 1.1e75, which raises floating-point exceptions. The automatic initializations
<!--page 463 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
- double_t x = 1.1e75;</pre>
+ double_t x = 1.1e75;
+</pre>
could be done at translation time, regardless of the expression evaluation method.
</small>
/* ... */
for (i = 0; i < n; i++) x + 1;
/* ... */
- }</pre>
+ }
+</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
the preceding loop could be treated as
<!--page 464 -->
<pre>
- if (0 < n) x + 1;</pre>
+ if (0 < n) x + 1;
+</pre>
<h4><a name="F.8.2" href="#F.8.2">F.8.2 Expression transformations</a></h4>
<p><!--para 1 -->
constants generally do not yield numerically equivalent
expressions, if the constants are exact then such
transformations can be made on IEC 60559 machines
- and others that round perfectly.</pre>
+ and others that round perfectly.
+</pre>
1 * x and x / 1 -> x The expressions 1 * x, x / 1, and x are equivalent
<pre>
- (on IEC 60559 machines, among others).<sup><a href="#note317"><b>317)</b></a></sup></pre>
+ (on IEC 60559 machines, among others).<sup><a href="#note317"><b>317)</b></a></sup>
+</pre>
x / x -> 1.0 The expressions x / x and 1.0 are not equivalent if x
<pre>
- can be zero, infinite, or NaN.</pre>
+ can be zero, infinite, or NaN.
+</pre>
x - y <-> x + (-y) The expressions x - y, x + (-y), and (-y) + x
<pre>
- are equivalent (on IEC 60559 machines, among others).</pre>
+ are equivalent (on IEC 60559 machines, among others).
+</pre>
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
- default rounding direction).<sup><a href="#note318"><b>318)</b></a></sup></pre>
+ default rounding direction).<sup><a href="#note318"><b>318)</b></a></sup>
+</pre>
x - x -> 0.0 The expressions x - x and 0.0 are not equivalent if
<pre>
- x is a NaN or infinite.</pre>
+ x is a NaN or infinite.
+</pre>
0 * x -> 0.0 The expressions 0 * x and 0.0 are not equivalent if
<pre>
- x is a NaN, infinite, or -0.</pre>
+ x is a NaN, infinite, or -0.
+</pre>
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
- rounding direction), not -0.</pre>
+ rounding direction), not -0.
+</pre>
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
- implementation can replace x - 0 by x, even if x</pre>
+ implementation can replace x - 0 by x, even if x
+</pre>
<!--page 465 -->
<pre>
- might be zero.</pre>
+ might be zero.
+</pre>
-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
- (unless rounding is downward).</pre>
+ (unless rounding is downward).
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
Examples include:
<pre>
- 1/(1/ (+-) (inf)) is (+-) (inf)</pre>
+ 1/(1/ (+-) (inf)) is (+-) (inf)
+</pre>
and
<pre>
- conj(csqrt(z)) is csqrt(conj(z)),</pre>
+ conj(csqrt(z)) is csqrt(conj(z)),
+</pre>
for complex z.
</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
- of the FENV_ACCESS pragma is ''off''.</pre>
+ of the FENV_ACCESS pragma is ''off''.
+</pre>
The sense of relational operators shall be maintained. This includes handling unordered
cases as expressed by the source code.
<p><!--para 2 -->
if (a < b)
f();
else
- g();</pre>
+ g();
+</pre>
is not equivalent to
<pre>
// calls f and raises ''invalid'' if a and b are unordered
if (a >= b)
g();
else
- f();</pre>
+ f();
+</pre>
nor to
<pre>
// calls f without raising ''invalid'' if a and b are unordered
if (isgreaterequal(a,b))
g();
else
- f();</pre>
+ f();
+</pre>
nor, unless the state of the FENV_ACCESS pragma is ''off'', to
<!--page 466 -->
<pre>
if (isless(a,b))
f();
else
- g();</pre>
+ g();
+</pre>
but is equivalent to
<pre>
if (!(a < b))
g();
else
- f();</pre>
+ f();
+</pre>
<h4><a name="F.8.4" href="#F.8.4">F.8.4 Constant arithmetic</a></h4>
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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note319" href="#note319">319)</a> 0 - 0 yields -0 instead of +0 just when the rounding direction is downward.
</small>
-<h3><a name="F.9" href="#F.9">F.9 Mathematics <math.h></a></h3>
+<h3><a name="F.9" href="#F.9">F.9 Mathematics <math.h></a></h3>
<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.
- Recommended practice
+<p><b>Recommended practice</b>
<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.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<li> atan2((+-)(inf), +(inf)) returns (+-)pi /4.
</ul>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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));
- }</pre>
+ }
+</pre>
<h5><a name="F.9.3.5" href="#F.9.3.5">F.9.3.5 The ilogb functions</a></h5>
<p><!--para 1 -->
return copysign(
isinf(value) ? 0.0 :
value - (*iptr), value);
- }</pre>
+ }
+</pre>
<h5><a name="F.9.3.13" href="#F.9.3.13">F.9.3.13 The scalbn and scalbln functions</a></h5>
<p><!--para 1 -->
result = rint(x); // or nearbyint instead of rint
fesetround(save_round);
return result;
- }</pre>
+ }
+</pre>
<h5><a name="F.9.6.2" href="#F.9.6.2">F.9.6.2 The floor functions</a></h5>
<p><!--para 1 -->
}
feupdateenv(&save_env);
return result;
- }</pre>
+ }
+</pre>
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);
- }</pre>
+ }
+</pre>
<h5><a name="F.9.7.2" href="#F.9.7.2">F.9.7.2 The remainder functions</a></h5>
<p><!--para 1 -->
The body of the fmax function might be<sup><a href="#note323"><b>323)</b></a></sup>
<pre>
{ return (isgreaterequal(x, y) ||
- isnan(y)) ? x : y; }</pre>
+ isnan(y)) ? x : y; }
+</pre>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<h2><a name="G" href="#G">Annex G</a></h2>
<pre>
(informative)
- IEC 60559-compatible complex arithmetic</pre>
+ IEC 60559-compatible complex arithmetic
+</pre>
<h3><a name="G.1" href="#G.1">G.1 Introduction</a></h3>
<p><!--para 1 -->
When a value of real type is converted to an imaginary type, the result is a positive
imaginary zero.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note324" href="#note324">324)</a> See <a href="#6.3.1.2">6.3.1.2</a>.
</small>
<!--page 481 -->
<h4><a name="G.5.1" href="#G.5.1">G.5.1 Multiplicative operators</a></h4>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
- * u iv u + iv</pre>
+ * u iv u + iv
+</pre>
<pre>
- x xu i(xv) (xu) + i(xv)</pre>
+ x xu i(xv) (xu) + i(xv)
+</pre>
<pre>
- iy i(yu) -yv (-yv) + i(yu)</pre>
+ iy i(yu) -yv (-yv) + i(yu)
+</pre>
-<p><!--para 3 -->
<pre>
- x + iy (xu) + i(yu) (-yv) + i(xv)</pre>
+ x + iy (xu) + i(yu) (-yv) + i(xv)
+</pre>
+<p><!--para 3 -->
If the second operand is not complex, then the result and floating-point exception
behavior of the / operator is defined by the usual mathematical formula:
<pre>
- / u iv</pre>
+ / u iv
+</pre>
<pre>
- x x/u i(-x/v)</pre>
+ x x/u i(-x/v)
+</pre>
<pre>
- iy i(y/u) y/v</pre>
+ iy i(y/u) y/v
+</pre>
-<p><!--para 4 -->
<pre>
- x + iy (x/u) + i(y/u) (y/v) + i(-x/v)</pre>
+ x + iy (x/u) + i(y/u) (y/v) + i(-x/v)
+</pre>
+<p><!--para 4 -->
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 -->
-<p><!--para 7 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.3"><complex.h></a>
}
}
return x + I * y;
- }</pre>
+ }
+</pre>
+<p><!--para 7 -->
This implementation achieves the required treatment of infinities at the cost of only one isnan test in
ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur.
<p><!--para 8 -->
EXAMPLE 2 Division of two double _Complex operands could be implemented as follows.
<!--page 484 -->
-<p><!--para 9 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.3"><complex.h></a>
}
}
return x + I * y;
- }</pre>
+ }
+</pre>
+<p><!--para 9 -->
Scaling the denominator alleviates the main overflow and underflow problem, which is more serious than
for multiplication. In the spirit of the multiplication example above, this code does not defend against
overflow and underflow in the calculation of the numerator. Scaling with the scalbn function, instead of
with division, provides better roundoff characteristics.
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
-<h6>Semantics</h6>
+<p><b>Semantics</b>
<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>
- + or - u iv u + iv</pre>
+ + or - u iv u + iv
+</pre>
<pre>
- x x(+-)u x (+-) iv (x (+-) u) (+-) iv</pre>
+ x x(+-)u x (+-) iv (x (+-) u) (+-) iv
+</pre>
<pre>
- iy (+-)u + iy i(y (+-) v) (+-)u + i(y (+-) v)</pre>
+ iy (+-)u + iy i(y (+-) v) (+-)u + i(y (+-) v)
+</pre>
<pre>
- x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v)</pre>
+ x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v)
+</pre>
-<h3><a name="G.6" href="#G.6">G.6 Complex arithmetic <complex.h></a></h3>
+<h3><a name="G.6" href="#G.6">G.6 Complex arithmetic <complex.h></a></h3>
<p><!--para 1 -->
The macros
<pre>
- imaginary</pre>
+ imaginary
+</pre>
and
<pre>
- _Imaginary_I</pre>
+ _Imaginary_I
+</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>
- I</pre>
+ I
+</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.
<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 7 -->
<pre>
cabs(x + iy) = hypot(x, y)
- carg(x + iy) = atan2(y, x)</pre>
+ carg(x + iy) = atan2(y, x)
+</pre>
+<p><!--para 7 -->
Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by
a formula in terms of other complex functions (whose special cases are specified below):
-<p><!--para 8 -->
<pre>
casin(z) = -i casinh(iz)
catan(z) = -i catanh(iz)
ccos(z) = ccosh(iz)
csin(z) = -i csinh(iz)
- ctan(z) = -i ctanh(iz)</pre>
+ ctan(z) = -i ctanh(iz)
+</pre>
+<p><!--para 8 -->
For the other functions, the following subclauses specify behavior for special cases,
including treatment of the ''invalid'' and ''divide-by-zero'' floating-point exceptions. For
families of functions, the specifications apply to all of the functions even though only the
<!--page 486 -->
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<p><small><a name="note326" href="#note326">326)</a> As noted in <a href="#G.3">G.3</a>, a complex value with at least one infinite part is regarded as an infinity even if its
other part is a NaN.
</small>
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>
-<h6>footnotes</h6>
+<p><b>Footnotes</b>
<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>
<!--page 492 -->
</ul>
-<h3><a name="G.7" href="#G.7">G.7 Type-generic math <tgmath.h></a></h3>
+<h3><a name="G.7" href="#G.7">G.7 Type-generic math <tgmath.h></a></h3>
<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,
asin(iy) = i asinh(y)
atan(iy) = i atanh(y)
asinh(iy) = i asin(y)
- atanh(iy) = i atan(y)</pre>
+ atanh(iy) = i atan(y)
+</pre>
<h2><a name="H" href="#H">Annex H</a></h2>
<pre>
(informative)
- Language independent arithmetic</pre>
+ Language independent arithmetic
+</pre>
<h3><a name="H.1" href="#H.1">H.1 Introduction</a></h3>
<p><!--para 1 -->
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>
- ULLONG_MAX</pre>
+ ULLONG_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''
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
cvtI' -> I (int)i, (long int)i, (long long int)i,
<pre>
(unsigned int)i, (unsigned long int)i,
- (unsigned long long int)i</pre>
+ (unsigned long long int)i
+</pre>
cvtF -> I (int)x, (long int)x, (long long int)x,
<pre>
(unsigned int)x, (unsigned long int)x,
- (unsigned long long int)x</pre>
+ (unsigned long long int)x
+</pre>
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
<p><!--para 2 -->
<!--page 499 -->
<h2><a name="I" href="#I">Annex I</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
- Common warnings</pre>
+ Common warnings
+</pre>
+<p><!--para 1 -->
An implementation may generate warnings in many situations, none of which are
specified as part of this International Standard. The following are a few of the more
common situations.
</ul>
<h2><a name="J" href="#J">Annex J</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
- Portability issues</pre>
+ Portability issues
+</pre>
+<p><!--para 1 -->
This annex collects some information about portability that appears in this International
Standard.
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>
- asm ( character-string-literal );</pre>
+ asm ( character-string-literal );
+</pre>
<h4><a name="J.5.11" href="#J.5.11">J.5.11 Multiple external definitions</a></h4>
<p><!--para 1 -->
projects / c-standard / blobdiff