<html><head><title>WG14/N1256 Septermber 7, 2007 ISO/IEC 9899:TC3</title></head><body>
-<pre>
-<!--page 1 -->
+<pre><!--page 1 -->
WG14/N1256 Committee Draft -- Septermber 7, 2007 ISO/IEC 9899:TC3
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)
p precision (the number of base-b digits in the significand)
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
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
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 -->
<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 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>
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 " \"
octal character \octal digits
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 \\.
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;
n = p - a; // n == 1
}
</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.
</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>
+<p><!--para 21 -->
Following the further successful assignments:
<pre>
s1 = malloc(sizeof (struct s) + 10);
struct { int n; double d[1]; } *s1, *s2;
</pre>
and:
-<p><!--para 22 -->
<pre>
double *dp;
dp = &(s1->d[0]); // valid
dp = &(s2->d[0]); // valid
*dp = 42; // undefined behavior
</pre>
+<p><!--para 22 -->
The assignment:
<pre>
*s1 = *s2;
</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>
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;
}
}
</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.
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)
{
return is_fahr ? cels(temp) : fahr(temp);
}
</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
<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>
+<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.
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="#7.6"><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>
+<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 202 -->
<p><!--para 3 -->
EXAMPLE
-<p><!--para 4 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
void f(double x)
/* ... */
}
</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>
<!--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>
+<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>
+<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>
+<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
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_sign_posn; // CHAR_MAX
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
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
SIGSEGV an invalid access to storage
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
<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>
/* ... */
fscanf(stdin,"%*[^\n]");
} while (!feof(stdin) && !ferror(stdin));
</pre>
+<p><!--para 20 -->
If the stdin stream contains the following lines:
<pre>
2 quarts of oil
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>
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the mblen function.
<h6>Returns</h6>
<p><!--para 4 -->
<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>
<!--page 415 -->
<h2><a name="A" href="#A">Annex A</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
Language syntax summary
</pre>
+<p><!--para 1 -->
NOTE The notation is described in <a href="#6.1">6.1</a>.
</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
+ 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>
(<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
+ 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>
(<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
+ 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
+ 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<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
+ 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>
(<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>
(<a href="#6.4.4.2">6.4.4.2</a>) binary-exponent-part:
<pre>
- p signopt digit-sequence
- P signopt digit-sequence
+ 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>
<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 "
+ " 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>
<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 ++
<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 ;
+ 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
+ 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>
</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<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>
(<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
+ 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>
<!--page 425 -->
<pre>
declarator
- declaratoropt : constant-expression
+ 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<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>
(<a href="#6.7.5">6.7.5</a>) declarator:
<pre>
- pointeropt direct-declarator
+ 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 )
+ 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
+ * 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>
(<a href="#6.7.5">6.7.5</a>) parameter-declaration:
<pre>
declaration-specifiers declarator
- declaration-specifiers abstract-declaratoropt
+ declaration-specifiers abstract-declarator<sub>opt</sub>
</pre>
(<a href="#6.7.5">6.7.5</a>) identifier-list:
<pre>
</pre>
(<a href="#6.7.6">6.7.6</a>) type-name:
<pre>
- specifier-qualifier-list abstract-declaratoropt
+ 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
+ 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 )
+ 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>
</pre>
(<a href="#6.7.8">6.7.8</a>) initializer-list:
<pre>
- designationopt initializer
- initializer-list , designationopt initializer
+ 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>
(<a href="#6.8.2">6.8.2</a>) compound-statement:
<pre>
- { block-item-listopt }
+ { block-item-list<sub>opt</sub> }
</pre>
(<a href="#6.8.2">6.8.2</a>) block-item-list:
<pre>
</pre>
(<a href="#6.8.3">6.8.3</a>) expression-statement:
<pre>
- expressionopt ;
+ expression<sub>opt</sub> ;
</pre>
(<a href="#6.8.4">6.8.4</a>) selection-statement:
<!--page 428 -->
<pre>
while ( expression ) statement
do statement while ( expression ) ;
- for ( expressionopt ; expressionopt ; expressionopt ) statement
- for ( declaration expressionopt ; expressionopt ) statement
+ 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 ;
+ return expression<sub>opt</sub> ;
</pre>
<h4><a name="A.2.4" href="#A.2.4">A.2.4 External definitions</a></h4>
</pre>
(<a href="#6.9.1">6.9.1</a>) function-definition:
<pre>
- declaration-specifiers declarator declaration-listopt compound-statement
+ declaration-specifiers declarator declaration-list<sub>opt</sub> compound-statement
</pre>
(<a href="#6.9.1">6.9.1</a>) declaration-list:
<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
+ group<sub>opt</sub>
</pre>
(<a href="#6.10">6.10</a>) group:
<pre>
(<a href="#6.10">6.10</a>) if-section:
<!--page 429 -->
<pre>
- if-group elif-groupsopt else-groupopt endif-line
+ 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
+ # 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>
</pre>
(<a href="#6.10">6.10</a>) elif-group:
<pre>
- # elif constant-expression new-line groupopt
+ # elif constant-expression new-line group<sub>opt</sub>
</pre>
(<a href="#6.10">6.10</a>) else-group:
<pre>
- # else new-line groupopt
+ # else new-line group<sub>opt</sub>
</pre>
(<a href="#6.10">6.10</a>) endif-line:
<pre>
<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
+ # 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
+ pp-tokens<sub>opt</sub> new-line
</pre>
(<a href="#6.10">6.10</a>) non-directive:
<pre>
(<a href="#6.10">6.10</a>) replacement-list:
<!--page 430 -->
<pre>
- pp-tokensopt
+ pp-tokens<sub>opt</sub>
</pre>
(<a href="#6.10">6.10</a>) pp-tokens:
<pre>
</pre>
<h2><a name="C" href="#C">Annex C</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
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>
+<p><!--para 1 -->
This clause lists the hexadecimal code values that are valid in universal character names
in identifiers.
<p><!--para 2 -->
</pre>
<h2><a name="E" href="#E">Annex E</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
-<h6> Implementation limits</h6>
+ 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 ULONG_MAX 4294967295
#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>
+<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_MIN_10_EXP -37
#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>
+<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 -->
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
/* ... */
}
</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
time.
<p><!--para 2 -->
EXAMPLE
-<p><!--para 3 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
/* ... */
}
</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
iy i(yu) -yv (-yv) + i(yu)
</pre>
-<p><!--para 3 -->
<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>
iy i(y/u) y/v
</pre>
-<p><!--para 4 -->
<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>
+<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>
+<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
<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>
+<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)
csin(z) = -i csinh(iz)
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 499 -->
<h2><a name="I" href="#I">Annex I</a></h2>
-<p><!--para 1 -->
<pre>
(informative)
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>
+<p><!--para 1 -->
This annex collects some information about portability that appears in this International
Standard.
projects / c-standard / blobdiff