<a name="1" href="#1"><b> 1. Scope</b></a>
1 This International Standard specifies the form and establishes the interpretation of
- programs written in the C programming language.1) It specifies
+ programs written in the C programming language.<sup><a href="#note1"><b>1)</b></a></sup> It specifies
-- the representation of C programs;
-- the syntax and constraints of the C language;
-- the semantic rules for interpreting C programs;
specific data-processing system or the capacity of a particular processor;
- 1) This International Standard is designed to promote the portability of C programs among a variety of
+ <sup><a name="note1" href="#note1"><b>1)</b></a></sup> 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.
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containing a #error preprocessing directive unless it is part of a group skipped by
conditional inclusion.
5 A strictly conforming program shall use only those features of the language and library
- specified in this International Standard.2) It shall not produce output dependent on any
+ specified in this International Standard.<sup><a href="#note2"><b>2)</b></a></sup> It shall not produce output dependent on any
unspecified, undefined, or implementation-defined behavior, and shall not exceed any
minimum implementation limit.
6 The two forms of conforming implementation are hosted and freestanding. A conforming
<a href="#7.9"><iso646.h></a>, <a href="#7.10"><limits.h></a>, <a href="#7.15"><stdarg.h></a>, <a href="#7.16"><stdbool.h></a>, <a href="#7.17"><stddef.h></a>, and
<a href="#7.18"><stdint.h></a>. A conforming implementation may have extensions (including additional
library functions), provided they do not alter the behavior of any strictly conforming
- program.3)
+ program.<sup><a href="#note3"><b>3)</b></a></sup>
-
2) A strictly conforming program can use conditional features (such as those in <a href="#F">annex F</a>) provided the
+
<sup><a name="note2" href="#note2"><b>2)</b></a></sup> 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:
#ifdef __STDC_IEC_559__ /* FE_UPWARD defined */
/* ... */
/* ... */
#endif
- 3) This implies that a conforming implementation reserves no identifiers other than those explicitly
+ <sup><a name="note3" href="#note3"><b>3)</b></a></sup> This implies that a conforming implementation reserves no identifiers other than those explicitly
reserved in this International Standard.
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-7 A conforming program is one that is acceptable to a conforming implementation.4)
+7 A conforming program is one that is acceptable to a conforming implementation.<sup><a href="#note4"><b>4)</b></a></sup>
8 An implementation shall be accompanied by a document that defines all implementation-
defined and locale-specific characteristics and all extensions.
Forward references: conditional inclusion (<a href="#6.10.1">6.10.1</a>), error directive (<a href="#6.10.5">6.10.5</a>),
- 4) Strictly conforming programs are intended to be maximally portable among conforming
+ <sup><a name="note4" href="#note4"><b>4)</b></a></sup> Strictly conforming programs are intended to be maximally portable among conforming
implementations. Conforming programs may depend upon nonportable features of a conforming
implementation.
preprocessing directives (<a href="#6.10">6.10</a>).
<a name="5.1.1.2" href="#5.1.1.2"><b> 5.1.1.2 Translation phases</b></a>
1 The precedence among the syntax rules of translation is specified by the following
- phases.5)
+ phases.<sup><a href="#note5"><b>5)</b></a></sup>
1. Physical source file multibyte characters are mapped, in an implementation-
defined manner, to the source character set (introducing new-line characters for
end-of-line indicators) if necessary. Trigraph sequences are replaced by
- 5) Implementations shall behave as if these separate phases occur, even though many are typically folded
+ <sup><a name="note5" href="#note5"><b>5)</b></a></sup> 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
and any external representation. The description is conceptual only, and does not specify any
of such a splice. A source file that is not empty shall end in a new-line character,
which shall not be immediately preceded by a backslash character before any such
splicing takes place.
- 3. The source file is decomposed into preprocessing tokens6) and sequences of
+ 3. The source file is decomposed into preprocessing tokens<sup><a href="#note6"><b>6)</b></a></sup> and sequences of
white-space characters (including comments). A source file shall not end in a
partial preprocessing token or in a partial comment. Each comment is replaced by
one space character. New-line characters are retained. Whether each nonempty
5. Each source character set member and escape sequence in character constants and
string literals is converted to the corresponding member of the execution character
set; if there is no corresponding member, it is converted to an implementation-
- defined member other than the null (wide) character.7)
+ defined member other than the null (wide) character.<sup><a href="#note7"><b>7)</b></a></sup>
6. Adjacent string literal tokens are concatenated.
7. White-space characters separating tokens are no longer significant. Each
preprocessing token is converted into a token. The resulting tokens are
-
6) As described in <a href="#6.4">6.4</a>, the process of dividing a source file's characters into preprocessing tokens is
+
<sup><a name="note6" href="#note6"><b>6)</b></a></sup> As described in <a href="#6.4">6.4</a>, the process of dividing a source file's characters into preprocessing tokens is
context-dependent. For example, see the handling of < within a #include preprocessing directive.
-7) An implementation need not convert all non-corresponding source characters to the same execution
+<sup><a name="note7" href="#note7"><b>7)</b></a></sup> An implementation need not convert all non-corresponding source characters to the same execution
character.
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an implementation-defined manner) if a preprocessing translation unit or translation unit
contains a violation of any syntax rule or constraint, even if the behavior is also explicitly
specified as undefined or implementation-defined. Diagnostic messages need not be
- produced in other circumstances.8)
+ produced in other circumstances.<sup><a href="#note8"><b>8)</b></a></sup>
2 EXAMPLE An implementation shall issue a diagnostic for the translation unit:
char i;
int i;
- 8) The intent is that an implementation should identify the nature of, and where possible localize, each
+ <sup><a name="note8" href="#note8"><b>8)</b></a></sup> The intent is that an implementation should identify the nature of, and where possible localize, each
violation. Of course, an implementation is free to produce any number of diagnostics as long as a
valid program is still correctly translated. It may also successfully translate an invalid program.
or with two parameters (referred to here as argc and argv, though any names may be
used, as they are local to the function in which they are declared):
int main(int argc, char *argv[]) { /* ... */ }
- or equivalent;9) or in some other implementation-defined manner.
+ or equivalent;<sup><a href="#note9"><b>9)</b></a></sup> or in some other implementation-defined manner.
2 If they are declared, the parameters to the main function shall obey the following
constraints:
-- The value of argc shall be nonnegative.
- 9) Thus, int can be replaced by a typedef name defined as int, or the type of argv can be written as
+ <sup><a name="note9" href="#note9"><b>9)</b></a></sup> 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.
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<a name="5.1.2.2.3" href="#5.1.2.2.3"><b> 5.1.2.2.3 Program termination</b></a>
1 If the return type of the main function is a type compatible with int, a return from the
initial call to the main function is equivalent to calling the exit function with the value
- returned by the main function as its argument;10) reaching the } that terminates the
+ returned by the main function as its argument;<sup><a href="#note10"><b>10)</b></a></sup> reaching the } that terminates the
main function returns a value of 0. If the return type is not compatible with int, the
termination status returned to the host environment is unspecified.
Forward references: 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>).
1 The semantic descriptions in this International Standard describe the behavior of an
abstract machine in which issues of optimization are irrelevant.
2 Accessing a volatile object, modifying an object, modifying a file, or calling a function
- that does any of those operations are all side effects,11) which are changes in the state of
+ that does any of those operations are all side effects,<sup><a href="#note11"><b>11)</b></a></sup> which are changes in the state of
the execution environment. Evaluation of an expression may produce side effects. At
certain specified points in the execution sequence called sequence points, all side effects
of previous evaluations shall be complete and no side effects of subsequent evaluations
-
10) In accordance with <a href="#6.2.4">6.2.4</a>, the lifetimes of objects with automatic storage duration declared in main
+
<sup><a name="note10" href="#note10"><b>10)</b></a></sup> 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.
- 11) The IEC 60559 standard for binary floating-point arithmetic requires certain user-accessible status
+ <sup><a name="note11" href="#note11"><b>11)</b></a></sup> 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
required to regard changes to it as side effects -- see <a href="#F">annex F</a> for details. The floating-point
preprocessing directives (<a href="#6.10">6.10</a>), string literals (<a href="#6.4.5">6.4.5</a>), comments (<a href="#6.4.9">6.4.9</a>), string (<a href="#7.1.1">7.1.1</a>).
<a name="5.2.1.1" href="#5.2.1.1"><b> 5.2.1.1 Trigraph sequences</b></a>
1 Before any other processing takes place, each occurrence of one of the following
- sequences of three characters (called trigraph sequences12)) is replaced with the
+ sequences of three characters (called trigraph sequences<sup><a href="#note12"><b>12)</b></a></sup>) is replaced with the
corresponding single character.
??= # ??) ] ??! |
??( [ ??' ^ ??> }
-- The presence, meaning, and representation of any additional members is locale-
specific.
- 12) The trigraph sequences enable the input of characters that are not defined in the Invariant Code Set as
+ <sup><a name="note12" href="#note12"><b>12)</b></a></sup> 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.
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discussed in clause 7.
<a name="5.2.4.1" href="#5.2.4.1"><b> 5.2.4.1 Translation limits</b></a>
1 The implementation shall be able to translate and execute at least one program that
- contains at least one instance of every one of the following limits:13)
+ contains at least one instance of every one of the following limits:<sup><a href="#note13"><b>13)</b></a></sup>
-- 127 nesting levels of blocks
-- 63 nesting levels of conditional inclusion
-- 12 pointer, array, and function declarators (in any combinations) modifying an
specifying a short identifier of 0000FFFF or less is considered 6 characters, each
- 13) Implementations should avoid imposing fixed translation limits whenever possible.
+ <sup><a name="note13" href="#note13"><b>13)</b></a></sup> Implementations should avoid imposing fixed translation limits whenever possible.
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universal character name specifying a short identifier of 00010000 or more is
considered 10 characters, and each extended source character is considered the same
- number of characters as the corresponding universal character name, if any)14)
+ number of characters as the corresponding universal character name, if any)<sup><a href="#note14"><b>14)</b></a></sup>
-- 4095 external identifiers in one translation unit
-- 511 identifiers with block scope declared in one block
-- 4095 macro identifiers simultaneously defined in one preprocessing translation unit
promotions. Their implementation-defined values shall be equal or greater in magnitude
-
14) See ''future language directions'' (<a href="#6.11.3">6.11.3</a>).
+
<sup><a name="note14" href="#note14"><b>14)</b></a></sup> See ''future language directions'' (<a href="#6.11.3">6.11.3</a>).
[<a name="p21" href="#p21">page 21</a>] (<a href="#Contents">Contents</a>)
expression, the value of CHAR_MIN shall be the same as that of SCHAR_MIN and the
value of CHAR_MAX shall be the same as that of SCHAR_MAX. Otherwise, the value of
CHAR_MIN shall be 0 and the value of CHAR_MAX shall be the same as that of
- UCHAR_MAX.15) The value UCHAR_MAX shall equal 2CHAR_BIT - 1.
+ UCHAR_MAX.<sup><a href="#note15"><b>15)</b></a></sup> The value UCHAR_MAX shall equal 2CHAR_BIT - 1.
Forward references: representations of types (<a href="#6.2.6">6.2.6</a>), conditional inclusion (<a href="#6.10.1">6.10.1</a>).
<a name="5.2.4.2.2" href="#5.2.4.2.2"><b> 5.2.4.2.2 Characteristics of floating types <float.h></b></a>
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.16) The following parameters are used to
+ 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:
s sign ((+-)1)
b base or radix of exponent representation (an integer > 1)
signaling NaN generally raises a floating-point exception when occurring as an
-
15) See <a href="#6.2.5">6.2.5</a>.
- 16) The floating-point model is intended to clarify the description of each floating-point characteristic and
+
<sup><a name="note15" href="#note15"><b>15)</b></a></sup> See <a href="#6.2.5">6.2.5</a>.
+ <sup><a name="note16" href="#note16"><b>16)</b></a></sup> 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.
[<a name="p23" href="#p23">page 23</a>] (<a href="#Contents">Contents</a>)
- arithmetic operand.17)
+ arithmetic operand.<sup><a href="#note17"><b>17)</b></a></sup>
4 An implementation may give zero and non-numeric values (such as infinities and NaNs) a
sign or may leave them unsigned. Wherever such values are unsigned, any requirement
in this International Standard to retrieve the sign shall produce an unspecified sign, and
point model representation is provided for all values except FLT_EVAL_METHOD and
FLT_ROUNDS.
7 The rounding mode for floating-point addition is characterized by the implementation-
- defined value of FLT_ROUNDS:18)
+ defined value of FLT_ROUNDS:<sup><a href="#note18"><b>18)</b></a></sup>
-1 indeterminable
0 toward zero
1 to nearest
of operations with floating operands and values subject to the usual arithmetic
conversions and of floating constants are evaluated to a format whose range and precision
may be greater than required by the type. The use of evaluation formats is characterized
- by the implementation-defined value of FLT_EVAL_METHOD:19)
+ by the implementation-defined value of FLT_EVAL_METHOD:<sup><a href="#note19"><b>19)</b></a></sup>
- 17) IEC 60559:1989 specifies quiet and signaling NaNs. For implementations that do not support
+ <sup><a name="note17" href="#note17"><b>17)</b></a></sup> IEC 60559:1989 specifies quiet and signaling NaNs. For implementations that do not support
IEC 60559:1989, the terms quiet NaN and signaling NaN are intended to apply to encodings with
similar behavior.
- 18) Evaluation of FLT_ROUNDS correctly reflects any execution-time change of rounding mode through
+ <sup><a name="note18" href="#note18"><b>18)</b></a></sup> Evaluation of FLT_ROUNDS correctly reflects any execution-time change of rounding mode through
the function fesetround in <a href="#7.6"><fenv.h></a>.
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- 19) The evaluation method determines evaluation formats of expressions involving all floating types, not
+ <sup><a name="note19" href="#note19"><b>19)</b></a></sup> The evaluation method determines evaluation formats of expressions involving all floating types, not
just real types. For example, if FLT_EVAL_METHOD is 1, then the product of two float
_Complex operands is represented in the double _Complex format, and its parts are evaluated to
double.
FLT_MAX_10_EXP +38
14 EXAMPLE 2 The following describes floating-point representations that also meet the requirements for
- single-precision and double-precision normalized numbers in IEC 60559,20) and the appropriate values in a
+ single-precision and double-precision normalized numbers in IEC 60559,<sup><a href="#note20"><b>20)</b></a></sup> and the appropriate values in a
<a href="#7.7"><float.h></a> header for types float and double:
24
x f = s2e (Sum) f k 2-k ,
FLT_EPSILON 0X1P-23F // hex constant
- 20) The floating-point model in that standard sums powers of b from zero, so the values of the exponent
+ <sup><a name="note20" href="#note20"><b>20)</b></a></sup> The floating-point model in that standard sums powers of b from zero, so the values of the exponent
limits are one less than shown here.
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source file inclusion (<a href="#6.10.2">6.10.2</a>), statements (<a href="#6.8">6.8</a>).
<a name="6.2.2" href="#6.2.2"><b> 6.2.2 Linkages of identifiers</b></a>
1 An identifier declared in different scopes or in the same scope more than once can be
- made to refer to the same object or function by a process called linkage.21) There are
+ made to refer to the same object or function by a process called linkage.<sup><a href="#note21"><b>21)</b></a></sup> There are
three kinds of linkage: external, internal, and none.
2 In the set of translation units and libraries that constitutes an entire program, each
declaration of a particular identifier with external linkage denotes the same object or
linkage denotes the same object or function. Each declaration of an identifier with no
linkage denotes a unique entity.
3 If the declaration of a file scope identifier for an object or a function contains the storage-
- class specifier static, the identifier has internal linkage.22)
+ class specifier static, the identifier has internal linkage.<sup><a href="#note22"><b>22)</b></a></sup>
4 For an identifier declared with the storage-class specifier extern in a scope in which a
- 21) There is no linkage between different identifiers.
- 22) A function declaration can contain the storage-class specifier static only if it is at file scope; see
+ <sup><a name="note21" href="#note21"><b>21)</b></a></sup> There is no linkage between different identifiers.
+ <sup><a name="note22" href="#note22"><b>22)</b></a></sup> A function declaration can contain the storage-class specifier static only if it is at file scope; see
<a href="#6.7.1">6.7.1</a>.
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- prior declaration of that identifier is visible,23) if the prior declaration specifies internal or
+ prior declaration of that identifier is visible,<sup><a href="#note23"><b>23)</b></a></sup> if the prior declaration specifies internal or
external linkage, the linkage of the identifier at the later declaration is the same as the
linkage specified at the prior declaration. If no prior declaration is visible, or if the prior
declaration specifies no linkage, then the identifier has external linkage.
translation unit, the syntactic context disambiguates uses that refer to different entities.
Thus, there are separate name spaces for various categories of identifiers, as follows:
-- label names (disambiguated by the syntax of the label declaration and use);
- -- the tags of structures, unions, and enumerations (disambiguated by following any24)
+ -- the tags of structures, unions, and enumerations (disambiguated by following any<sup><a href="#note24"><b>24)</b></a></sup>
of the keywords struct, union, or enum);
-- the members of structures or unions; each structure or union has a separate name
space for its members (disambiguated by the type of the expression used to access the
-
23) As specified in <a href="#6.2.1">6.2.1</a>, the later declaration might hide the prior declaration.
- 24) There is only one name space for tags even though three are possible.
+
<sup><a name="note23" href="#note23"><b>23)</b></a></sup> As specified in <a href="#6.2.1">6.2.1</a>, the later declaration might hide the prior declaration.
+ <sup><a name="note24" href="#note24"><b>24)</b></a></sup> There is only one name space for tags even though three are possible.
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1 An object has a storage duration that determines its lifetime. There are three storage
durations: static, automatic, and allocated. Allocated storage is described in <a href="#7.20.3">7.20.3</a>.
2 The lifetime of an object is the portion of program execution during which storage is
- guaranteed to be reserved for it. An object exists, has a constant address,25) and retains
- its last-stored value throughout its lifetime.26) If an object is referred to outside of its
+ guaranteed to be reserved for it. An object exists, has a constant address,<sup><a href="#note25"><b>25)</b></a></sup> and retains
+ its last-stored value throughout its lifetime.<sup><a href="#note26"><b>26)</b></a></sup> If an object is referred to outside of its
lifetime, the behavior is undefined. The value of a pointer becomes indeterminate when
the object it points to reaches the end of its lifetime.
3 An object whose identifier is declared with external or internal linkage, or with the
time the declaration is reached.
6 For such an object that does have a variable length array type, its lifetime extends from
the declaration of the object until execution of the program leaves the scope of the
- declaration.27) If the scope is entered recursively, a new instance of the object is created
+ declaration.<sup><a href="#note27"><b>27)</b></a></sup> If the scope is entered recursively, a new instance of the object is created
each time. The initial value of the object is indeterminate.
Forward references: statements (<a href="#6.8">6.8</a>), function calls (<a href="#6.5.2.2">6.5.2.2</a>), declarators (<a href="#6.7.5">6.7.5</a>), array
declarators (<a href="#6.7.5.2">6.7.5.2</a>), initialization (<a href="#6.7.8">6.7.8</a>).
- 25) The term ''constant address'' means that two pointers to the object constructed at possibly different
+ <sup><a name="note25" href="#note25"><b>25)</b></a></sup> 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.
- 26) In the case of a volatile object, the last store need not be explicit in the program.
- 27) Leaving the innermost block containing the declaration, or jumping to a point in that block or an
+ <sup><a name="note26" href="#note26"><b>26)</b></a></sup> In the case of a volatile object, the last store need not be explicit in the program.
+ <sup><a name="note27" href="#note27"><b>27)</b></a></sup> Leaving the innermost block containing the declaration, or jumping to a point in that block or an
embedded block prior to the declaration, leaves the scope of the declaration.
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4 There are five standard signed integer types, designated as signed char, short
int, int, long int, and long long int. (These and other types may be
designated in several additional ways, as described in <a href="#6.7.2">6.7.2</a>.) There may also be
- implementation-defined extended signed integer types.28) The standard and extended
- signed integer types are collectively called signed integer types.29)
+ implementation-defined extended signed integer types.<sup><a href="#note28"><b>28)</b></a></sup> The standard and extended
+ signed integer types are collectively called signed integer types.<sup><a href="#note29"><b>29)</b></a></sup>
5 An object declared as type signed char occupies the same amount of storage as a
''plain'' char object. A ''plain'' int object has the natural size suggested by the
architecture of the execution environment (large enough to contain any value in the range
types are the standard unsigned integer types. The unsigned integer types that
correspond to the extended signed integer types are the extended unsigned integer types.
The standard and extended unsigned integer types are collectively called unsigned integer
- types.30)
+ types.<sup><a href="#note30"><b>30)</b></a></sup>
- 28) Implementation-defined keywords shall have the form of an identifier reserved for any use as
+ <sup><a name="note28" href="#note28"><b>28)</b></a></sup> 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>.
- 29) Therefore, any statement in this Standard about signed integer types also applies to the extended
+ <sup><a name="note29" href="#note29"><b>29)</b></a></sup> Therefore, any statement in this Standard about signed integer types also applies to the extended
signed integer types.
- 30) Therefore, any statement in this Standard about unsigned integer types also applies to the extended
+ <sup><a name="note30" href="#note30"><b>30)</b></a></sup> Therefore, any statement in this Standard about unsigned integer types also applies to the extended
unsigned integer types.
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subrange of the values of the other type.
9 The range of nonnegative values of a signed integer type is a subrange of the
corresponding unsigned integer type, and the representation of the same value in each
- type is the same.31) A computation involving unsigned operands can never overflow,
+ type is the same.<sup><a href="#note31"><b>31)</b></a></sup> A computation involving unsigned operands can never overflow,
because a result that cannot be represented by the resulting unsigned integer type is
reduced modulo the number that is one greater than the largest value that can be
represented by the resulting type.
10 There are three real floating types, designated as float, double, and long
- double.32) The set of values of the type float is a subset of the set of values of the
+ double.<sup><a href="#note32"><b>32)</b></a></sup> The set of values of the type float is a subset of the set of values of the
type double; the set of values of the type double is a subset of the set of values of the
type long double.
11 There are three complex types, designated as float _Complex, double
- _Complex, and long double _Complex.33) The real floating and complex types
+ _Complex, and long double _Complex.<sup><a href="#note33"><b>33)</b></a></sup> The real floating and complex types
are collectively called the floating types.
12 For each floating type there is a corresponding real type, which is always a real floating
type. For real floating types, it is the same type. For complex types, it is the type given
number.
14 The type char, the signed and unsigned integer types, and the floating types are
collectively called the basic types. Even if the implementation defines two or more basic
- types to have the same representation, they are nevertheless different types.34)
+ types to have the same representation, they are nevertheless different types.<sup><a href="#note34"><b>34)</b></a></sup>
- 31) The same representation and alignment requirements are meant to imply interchangeability as
+ <sup><a name="note31" href="#note31"><b>31)</b></a></sup> The same representation and alignment requirements are meant to imply interchangeability as
arguments to functions, return values from functions, and members of unions.
-
32) See ''future language directions'' (<a href="#6.11.1">6.11.1</a>).
-
33) A specification for imaginary types is in informative <a href="#G">annex G</a>.
- 34) An implementation may define new keywords that provide alternative ways to designate a basic (or
+
<sup><a name="note32" href="#note32"><b>32)</b></a></sup> See ''future language directions'' (<a href="#6.11.1">6.11.1</a>).
+
<sup><a name="note33" href="#note33"><b>33)</b></a></sup> A specification for imaginary types is in informative <a href="#G">annex G</a>.
+ <sup><a name="note34" href="#note34"><b>34)</b></a></sup> An implementation may define new keywords that provide alternative ways to designate a basic (or
any other) type; this does not violate the requirement that all basic types be different.
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>.
15 The three types char, signed char, and unsigned char are collectively called
the character types. The implementation shall define char to have the same range,
- representation, and behavior as either signed char or unsigned char.35)
+ representation, and behavior as either signed char or unsigned char.<sup><a href="#note35"><b>35)</b></a></sup>
16 An enumeration comprises a set of named integer constant values. Each distinct
enumeration constitutes a different enumerated type.
17 The type char, the signed and unsigned integer types, and the enumerated types are
20 Any number of derived types can be constructed from the object, function, and
incomplete types, as follows:
-- An array type describes a contiguously allocated nonempty set of objects with a
- particular member object type, called the element type.36) Array types are
+ particular member object type, called the element type.<sup><a href="#note36"><b>36)</b></a></sup> Array types are
characterized by their element type and by the number of elements in the array. An
array type is said to be derived from its element type, and if its element type is T , the
array type is sometimes called ''array of T ''. The construction of an array type from
-
35) CHAR_MIN, defined in <a href="#7.10"><limits.h></a>, will have one of the values 0 or SCHAR_MIN, and this can be
+
<sup><a name="note35" href="#note35"><b>35)</b></a></sup> CHAR_MIN, defined in <a href="#7.10"><limits.h></a>, will have one of the values 0 or SCHAR_MIN, and this can be
used to distinguish the two options. Irrespective of the choice made, char is a separate type from the
other two and is not compatible with either.
- 36) Since object types do not include incomplete types, an array of incomplete type cannot be constructed.
+ <sup><a name="note36" href="#note36"><b>36)</b></a></sup> Since object types do not include incomplete types, an array of incomplete type cannot be constructed.
[<a name="p35" href="#p35">page 35</a>] (<a href="#Contents">Contents</a>)
pointer type from a referenced type is called ''pointer type derivation''.
These methods of constructing derived types can be applied recursively.
21 Arithmetic types and pointer types are collectively called scalar types. Array and
- structure types are collectively called aggregate types.37)
+ structure types are collectively called aggregate types.<sup><a href="#note37"><b>37)</b></a></sup>
22 An array type of unknown size is an incomplete type. It is completed, for an identifier of
that type, by specifying the size in a later declaration (with internal or external linkage).
A structure or union type of unknown content (as described in <a href="#6.7.2.3">6.7.2.3</a>) is an incomplete
derived type (as noted above in the construction of derived types), or the type itself if the
type consists of no derived types.
26 Any type so far mentioned is an unqualified type. Each unqualified type has several
- qualified versions of its type,38) corresponding to the combinations of one, two, or all
+ qualified versions of its type,<sup><a href="#note38"><b>38)</b></a></sup> corresponding to the combinations of one, two, or all
three of the const, volatile, and restrict qualifiers. The qualified or unqualified
versions of a type are distinct types that belong to the same type category and have the
- same representation and alignment requirements.39) A derived type is not qualified by the
+ same representation and alignment requirements.<sup><a href="#note39"><b>39)</b></a></sup> A derived type is not qualified by the
qualifiers (if any) of the type from which it is derived.
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
compatible types shall have the same representation and alignment requirements. All
- 37) Note that aggregate type does not include union type because an object with union type can only
+ <sup><a name="note37" href="#note37"><b>37)</b></a></sup> Note that aggregate type does not include union type because an object with union type can only
contain one member at a time.
-
38) See <a href="#6.7.3">6.7.3</a> regarding qualified array and function types.
- 39) The same representation and alignment requirements are meant to imply interchangeability as
+
<sup><a name="note38" href="#note38"><b>38)</b></a></sup> See <a href="#6.7.3">6.7.3</a> regarding qualified array and function types.
+ <sup><a name="note39" href="#note39"><b>39)</b></a></sup> The same representation and alignment requirements are meant to imply interchangeability as
arguments to functions, return values from functions, and members of unions.
[<a name="p36" href="#p36">page 36</a>] (<a href="#Contents">Contents</a>)
the number, order, and encoding of which are either explicitly specified or
implementation-defined.
3 Values stored in unsigned bit-fields and objects of type unsigned char shall be
- represented using a pure binary notation.40)
+ represented using a pure binary notation.<sup><a href="#note40"><b>40)</b></a></sup>
4 Values stored in non-bit-field objects of any other object type consist of n x CHAR_BIT
bits, where n is the size of an object of that type, in bytes. The value may be copied into
an object of type unsigned char [n] (e.g., by memcpy); the resulting set of bytes is
value of an object has such a representation and is read by an lvalue expression that does
not have character type, the behavior is undefined. If such a representation is produced
by a side effect that modifies all or any part of the object by an lvalue expression that
- does not have character type, the behavior is undefined.41) Such a representation is called
+ does not have character type, the behavior is undefined.<sup><a href="#note41"><b>41)</b></a></sup> Such a representation is called
- 40) A positional representation for integers that uses the binary digits 0 and 1, in which the values
+ <sup><a name="note40" href="#note40"><b>40)</b></a></sup> 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
a trap representation.
6 When a value is stored in an object of structure or union type, including in a member
object, the bytes of the object representation that correspond to any padding bytes take
- unspecified values.42) The value of a structure or union object is never a trap
+ unspecified values.<sup><a href="#note42"><b>42)</b></a></sup> The value of a structure or union object is never a trap
representation, even though the value of a member of the structure or union object may be
a trap representation.
7 When a value is stored in a member of an object of union type, the bytes of the object
representation that do not correspond to that member but do correspond to other members
take unspecified values.
8 Where an operator is applied to a value that has more than one object representation,
- which object representation is used shall not affect the value of the result.43) Where a
+ which object representation is used shall not affect the value of the result.<sup><a href="#note43"><b>43)</b></a></sup> Where a
value is stored in an object using a type that has more than one object representation for
that value, it is unspecified which representation is used, but a trap representation shall
not be generated.
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
- known as the value representation. The values of any padding bits are unspecified.44)
+ known as the value representation. The values of any padding bits are unspecified.<sup><a href="#note44"><b>44)</b></a></sup>
2 For signed integer types, the bits of the object representation shall be divided into three
groups: value bits, padding bits, and the sign bit. There need not be any padding bits;
- 41) Thus, an automatic variable can be initialized to a trap representation without causing undefined
+ <sup><a name="note41" href="#note41"><b>41)</b></a></sup> 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.
- 42) Thus, for example, structure assignment need not copy any padding bits.
- 43) It is possible for objects x and y with the same effective type T to have the same value when they are
+ <sup><a name="note42" href="#note42"><b>42)</b></a></sup> Thus, for example, structure assignment need not copy any padding bits.
+ <sup><a name="note43" href="#note43"><b>43)</b></a></sup> It is possible for objects x and y with the same effective type T to have the same value when they are
accessed as objects of type T, but to have different values in other contexts. In particular, if == is
defined for type T, then x == y does not imply that memcmp(&x, &y, sizeof (T)) == 0.
Furthermore, x == y does not necessarily imply that x and y have the same value; other operations
on values of type T may distinguish between them.
- 44) Some combinations of padding bits might generate trap representations, for example, if one padding
+ <sup><a name="note44" href="#note44"><b>44)</b></a></sup> 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
with unsigned types. All other combinations of padding bits are alternative object representations of
and whether a negative zero becomes a normal zero when stored in an object.
4 If the implementation does not support negative zeros, the behavior of the &, |, ^, ~, <<,
and >> operators with arguments that would produce such a value is undefined.
-5 The values of any padding bits are unspecified.45) A valid (non-trap) object representation
+5 The values of any padding bits are unspecified.<sup><a href="#note45"><b>45)</b></a></sup> A valid (non-trap) object representation
of a signed integer type where the sign bit is zero is a valid object representation of the
corresponding unsigned type, and shall represent the same value. For any integer type,
the object representation where all the bits are zero shall be a representation of the value
including any sign bit; thus for unsigned integer types the two values are the same, while
- 45) Some combinations of padding bits might generate trap representations, for example, if one padding
+ <sup><a name="note45" href="#note45"><b>45)</b></a></sup> 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. All other
combinations of padding bits are alternative object representations of the value specified by the value
<a name="6.2.7" href="#6.2.7"><b> 6.2.7 Compatible type and composite type</b></a>
1 Two types have compatible type if their types are the same. Additional rules for
determining whether two types are compatible are described in <a href="#6.7.2">6.7.2</a> for type specifiers,
- in <a href="#6.7.3">6.7.3</a> for type qualifiers, and in <a href="#6.7.5">6.7.5</a> for declarators.46) Moreover, two structure,
+ in <a href="#6.7.3">6.7.3</a> for type qualifiers, and in <a href="#6.7.5">6.7.5</a> for declarators.<sup><a href="#note46"><b>46)</b></a></sup> Moreover, two structure,
union, or enumerated types declared in separate translation units are compatible if their
tags and members satisfy the following requirements: If one is declared with a tag, the
other shall be declared with the same tag. If both are complete types, then the following
parameters.
These rules apply recursively to the types from which the two types are derived.
4 For an identifier with internal or external linkage declared in a scope in which a prior
- declaration of that identifier is visible,47) if the prior declaration specifies internal or
+ declaration of that identifier is visible,<sup><a href="#note47"><b>47)</b></a></sup> if the prior declaration specifies internal or
external linkage, the type of the identifier at the later declaration becomes the composite
type.
- 46) Two types need not be identical to be compatible.
-
47) As specified in <a href="#6.2.1">6.2.1</a>, the later declaration might hide the prior declaration.
+ <sup><a name="note46" href="#note46"><b>46)</b></a></sup> Two types need not be identical to be compatible.
+
<sup><a name="note47" href="#note47"><b>47)</b></a></sup> As specified in <a href="#6.2.1">6.2.1</a>, the later declaration might hide the prior declaration.
[<a name="p40" href="#p40">page 40</a>] (<a href="#Contents">Contents</a>)
-- A bit-field of type _Bool, int, signed int, or unsigned int.
If an int can represent all values of the original type, the value is converted to an int;
otherwise, it is converted to an unsigned int. These are called the integer
- promotions.48) All other types are unchanged by the integer promotions.
+ promotions.<sup><a href="#note48"><b>48)</b></a></sup> All other types are unchanged by the integer promotions.
3 The integer promotions preserve value including sign. As discussed earlier, whether a
''plain'' char is treated as signed is implementation-defined.
Forward references: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), structure and union specifiers
the value can be represented by the new type, it is unchanged.
2 Otherwise, if the new type is unsigned, the value is converted by repeatedly adding or
subtracting one more than the maximum value that can be represented in the new type
- until the value is in the range of the new type.49)
+ until the value is in the range of the new type.<sup><a href="#note49"><b>49)</b></a></sup>
3 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.
<a name="6.3.1.4" href="#6.3.1.4"><b> 6.3.1.4 Real floating and integer</b></a>
1 When a finite value of real floating type is converted to an integer type other than _Bool,
the fractional part is discarded (i.e., the value is truncated toward zero). If the value of
- the integral part cannot be represented by the integer type, the behavior is undefined.50)
+ the integral part cannot be represented by the integer type, the behavior is undefined.<sup><a href="#note50"><b>50)</b></a></sup>
2 When a value of integer type is converted to a real floating type, if the value being
converted can be represented exactly in the new type, it is unchanged. If the value being
converted is in the range of values that can be represented but cannot be represented
- 48) The integer promotions are applied only: as part of the usual arithmetic conversions, to certain
+ <sup><a name="note48" href="#note48"><b>48)</b></a></sup> 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.
- 49) The rules describe arithmetic on the mathematical value, not the value of a given type of expression.
- 50) The remaindering operation performed when a value of integer type is converted to unsigned type
+ <sup><a name="note49" href="#note49"><b>49)</b></a></sup> The rules describe arithmetic on the mathematical value, not the value of a given type of expression.
+ <sup><a name="note50" href="#note50"><b>50)</b></a></sup> 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).
corresponding real type is double.
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.51)
+ 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
following rules are applied to the promoted operands:
If both operands have the same type, then no further conversion is needed.
corresponding to the type of the operand with signed integer type.
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.52)
+ changed thereby.<sup><a href="#note52"><b>52)</b></a></sup>
- 51) For example, addition of a double _Complex and a float entails just the conversion of the
+ <sup><a name="note51" href="#note51"><b>51)</b></a></sup> 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).
- 52) The cast and assignment operators are still required to perform their specified conversions as
+ <sup><a name="note52" href="#note52"><b>52)</b></a></sup> The cast and assignment operators are still required to perform their specified conversions as
described in <a href="#6.3.1.4">6.3.1.4</a> and <a href="#6.3.1.5">6.3.1.5</a>.
[<a name="p45" href="#p45">page 45</a>] (<a href="#Contents">Contents</a>)
<a name="6.3.2" href="#6.3.2"><b> 6.3.2 Other operands</b></a>
<a name="6.3.2.1" href="#6.3.2.1"><b> 6.3.2.1 Lvalues, arrays, and function designators</b></a>
-1 An lvalue is an expression with an object type or an incomplete type other than void;53)
+1 An lvalue is an expression with an object type or an incomplete type other than void;<sup><a href="#note53"><b>53)</b></a></sup>
if an lvalue does not designate an object when it is evaluated, the behavior is undefined.
When an object is said to have a particular type, the type is specified by the lvalue used to
designate the object. A modifiable lvalue is an lvalue that does not have array type, does
the array object and is not an lvalue. If the array object has register storage class, the
behavior is undefined.
4 A function designator is an expression that has function type. Except when it is the
- operand of the sizeof operator54) or the unary & operator, a function designator with
+ operand of the sizeof operator<sup><a href="#note54"><b>54)</b></a></sup> or the unary & operator, a function designator with
type ''function returning type'' is converted to an expression that has type ''pointer to
function returning type''.
Forward references: address and indirection operators (<a href="#6.5.3.2">6.5.3.2</a>), assignment operators
(<a href="#6.5.3.1">6.5.3.1</a>), the sizeof operator (<a href="#6.5.3.4">6.5.3.4</a>), structure and union members (<a href="#6.5.2.3">6.5.2.3</a>).
- 53) The name ''lvalue'' comes originally from the assignment expression E1 = E2, in which the left
+ <sup><a name="note53" href="#note53"><b>53)</b></a></sup> 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
as the ''value of an expression''.
An obvious example of an lvalue is an identifier of an object. As a further example, if E is a unary
expression that is a pointer to an object, *E is an lvalue that designates the object to which E points.
- 54) Because this conversion does not occur, the operand of the sizeof operator remains a function
+ <sup><a name="note54" href="#note54"><b>54)</b></a></sup> Because this conversion does not occur, the operand of the sizeof operator remains a function
designator and violates the constraint in <a href="#6.5.3.4">6.5.3.4</a>.
[<a name="p46" href="#p46">page 46</a>] (<a href="#Contents">Contents</a>)
the q-qualified version of the type; the values stored in the original and converted pointers
shall compare equal.
3 An integer constant expression with the value 0, or such an expression cast to type
- void *, is called a null pointer constant.55) If a null pointer constant is converted to a
+ void *, is called a null pointer constant.<sup><a href="#note55"><b>55)</b></a></sup> If a null pointer constant is converted to a
pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal
to a pointer to any object or function.
4 Conversion of a null pointer to another pointer type yields a null pointer of that type.
Any two null pointers shall compare equal.
5 An integer may be converted to any pointer type. Except as previously specified, the
result is implementation-defined, might not be correctly aligned, might not point to an
- entity of the referenced type, and might be a trap representation.56)
+ entity of the referenced type, and might be a trap representation.<sup><a href="#note56"><b>56)</b></a></sup>
6 Any pointer type may be converted to an integer type. Except as previously specified, the
result is implementation-defined. If the result cannot be represented in the integer type,
the behavior is undefined. The result need not be in the range of values of any integer
type.
7 A pointer to an object or incomplete type may be converted to a pointer to a different
- object or incomplete type. If the resulting pointer is not correctly aligned57) for the
+ object or incomplete type. If the resulting pointer is not correctly aligned<sup><a href="#note57"><b>57)</b></a></sup> for the
pointed-to type, the behavior is undefined. Otherwise, when converted back again, the
result shall compare equal to the original pointer. When a pointer to an object is
-
55) 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>.
- 56) The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to
+
<sup><a name="note55" href="#note55"><b>55)</b></a></sup> 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>.
+ <sup><a name="note56" href="#note56"><b>56)</b></a></sup> The mapping functions for converting a pointer to an integer or an integer to a pointer are intended to
be consistent with the addressing structure of the execution environment.
- 57) In general, the concept ''correctly aligned'' is transitive: if a pointer to type A is correctly aligned for a
+ <sup><a name="note57" href="#note57"><b>57)</b></a></sup> In general, the concept ''correctly aligned'' is transitive: if a pointer to type A is correctly aligned for a
pointer to type B, which in turn is correctly aligned for a pointer to type C, then a pointer to type A is
correctly aligned for a pointer to type C.
phases 3 through 6. The categories of preprocessing tokens are: header names,
identifiers, preprocessing numbers, character constants, string literals, punctuators, and
single non-white-space characters that do not lexically match the other preprocessing
- token categories.58) If a ' or a " character matches the last category, the behavior is
+ token categories.<sup><a href="#note58"><b>58)</b></a></sup> If a ' or a " character matches the last category, the behavior is
undefined. Preprocessing tokens can be separated by white space; this consists of
comments (described later), or white-space characters (space, horizontal tab, new-line,
vertical tab, and form-feed), or both. As described in <a href="#6.10">6.10</a>, in certain circumstances
-
58) 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
+
<sup><a name="note58" href="#note58"><b>58)</b></a></sup> 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.
[<a name="p49" href="#p49">page 49</a>] (<a href="#Contents">Contents</a>)
<b> Semantics</b>
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
- specifying imaginary types.59)
+ specifying imaginary types.<sup><a href="#note59"><b>59)</b></a></sup>
-
59) One possible specification for imaginary types appears in <a href="#G">annex G</a>.
+
<sup><a name="note59" href="#note59"><b>59)</b></a></sup> One possible specification for imaginary types appears in <a href="#G">annex G</a>.
[<a name="p50" href="#p50">page 50</a>] (<a href="#Contents">Contents</a>)
one or more entities as described in <a href="#6.2.1">6.2.1</a>. Lowercase and uppercase letters are distinct.
There is no specific limit on the maximum length of an identifier.
3 Each universal character name in an identifier shall designate a character whose encoding
- in ISO/IEC 10646 falls into one of the ranges specified in <a href="#D">annex D</a>.60) The initial
+ in ISO/IEC 10646 falls into one of the ranges specified in <a href="#D">annex D</a>.<sup><a href="#note60"><b>60)</b></a></sup> The initial
character shall not be a universal character name designating a digit. An implementation
may allow multibyte characters that are not part of the basic source character set to
appear in identifiers; which characters and their correspondence to universal character
to a keyword.
- 60) On systems in which linkers cannot accept extended characters, an encoding of the universal character
+ <sup><a name="note60" href="#note60"><b>60)</b></a></sup> On systems in which linkers cannot accept extended characters, an encoding of the universal character
name may be used in forming valid external identifiers. For example, some otherwise unused
character or sequence of characters may be used to encode the \u in a universal character name.
Extended characters may produce a long external identifier.
1 The identifier __func__ shall be implicitly declared by the translator as if,
immediately following the opening brace of each function definition, the declaration
static const char __func__[] = "function-name";
- appeared, where function-name is the name of the lexically-enclosing function.61)
+ appeared, where function-name is the name of the lexically-enclosing function.<sup><a href="#note61"><b>61)</b></a></sup>
2 This name is encoded as if the implicit declaration had been written in the source
character set and then translated into the execution character set as indicated in translation
phase 5.
-
61) Since the name __func__ is reserved for any use by the implementation (<a href="#7.1.3">7.1.3</a>), if any other
+
<sup><a name="note61" href="#note61"><b>61)</b></a></sup> 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.
[<a name="p52" href="#p52">page 52</a>] (<a href="#Contents">Contents</a>)
<b> Constraints</b>
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.62)
+ DFFF inclusive.<sup><a href="#note62"><b>62)</b></a></sup>
<b> Description</b>
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.
<b> Semantics</b>
4 The universal character name \Unnnnnnnn designates the character whose eight-digit
- short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.63) Similarly, the universal
+ short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.<sup><a href="#note63"><b>63)</b></a></sup> Similarly, the universal
character name \unnnn designates the character whose four-digit short identifier is nnnn
(and whose eight-digit short identifier is 0000nnnn).
- 62) The disallowed characters are the characters in the basic character set and the code positions reserved
+ <sup><a name="note62" href="#note62"><b>62)</b></a></sup> 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).
- 63) Short identifiers for characters were first specified in ISO/IEC 10646-1/AMD9:1997.
+ <sup><a name="note63" href="#note63"><b>63)</b></a></sup> Short identifiers for characters were first specified in ISO/IEC 10646-1/AMD9:1997.
[<a name="p53" href="#p53">page 53</a>] (<a href="#Contents">Contents</a>)
7 The translation-time conversion of floating constants should match the execution-time
conversion of character strings by library functions, such as strtod, given matching
inputs suitable for both conversions, the same result format, and default execution-time
- rounding.64)
+ rounding.<sup><a href="#note64"><b>64)</b></a></sup>
- 64) The specification for the library functions recommends more accurate conversion than required for
+ <sup><a name="note64" href="#note64"><b>64)</b></a></sup> 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>).
[<a name="p58" href="#p58">page 58</a>] (<a href="#Contents">Contents</a>)
8 In addition, characters not in the basic character set are representable by universal
character names and certain nongraphic characters are representable by escape sequences
consisting of the backslash \ followed by a lowercase letter: \a, \b, \f, \n, \r, \t,
- and \v.65)
+ and \v.<sup><a href="#note65"><b>65)</b></a></sup>
-
65) The semantics of these characters were discussed in <a href="#5.2.2">5.2.2</a>. If any other character follows a backslash,
+
<sup><a name="note65" href="#note65"><b>65)</b></a></sup> 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>).
[<a name="p60" href="#p60">page 60</a>] (<a href="#Contents">Contents</a>)
multibyte character sequence is treated as a wide string literal; otherwise, it is treated as a
character string literal.
5 In translation phase 7, a byte or code of value zero is appended to each multibyte
- character sequence that results from a string literal or literals.66) The multibyte character
+ character sequence that results from a string literal or literals.<sup><a href="#note66"><b>66)</b></a></sup> The multibyte character
sequence is then used to initialize an array of static storage duration and length just
sufficient to contain the sequence. For character string literals, the array elements have
type char, and are initialized with the individual bytes of the multibyte character
sequence; for wide string literals, the array elements have type wchar_t, and are
initialized with the sequence of wide characters corresponding to the multibyte character
-
66) 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
+
<sup><a name="note66" href="#note66"><b>66)</b></a></sup> 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.
[<a name="p62" href="#p62">page 62</a>] (<a href="#Contents">Contents</a>)
[<a name="p63" href="#p63">page 63</a>] (<a href="#Contents">Contents</a>)
-3 In all aspects of the language, the six tokens67)
+3 In all aspects of the language, the six tokens<sup><a href="#note67"><b>67)</b></a></sup>
<: :> <% %> %: %:%:
behave, respectively, the same as the six tokens
[ ] { } # ##
- except for their spelling.68)
+ except for their spelling.<sup><a href="#note68"><b>68)</b></a></sup>
Forward references: 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>).
<a name="6.4.7" href="#6.4.7"><b> 6.4.7 Header names</b></a>
- 67) These tokens are sometimes called ''digraphs''.
-
68) Thus [ and <: behave differently when ''stringized'' (see <a href="#6.10.3.2">6.10.3.2</a>), but can otherwise be freely
+ <sup><a name="note67" href="#note67"><b>67)</b></a></sup> These tokens are sometimes called ''digraphs''.
+
<sup><a name="note68" href="#note68"><b>68)</b></a></sup> Thus [ and <: behave differently when ''stringized'' (see <a href="#6.10.3.2">6.10.3.2</a>), but can otherwise be freely
interchanged.
[<a name="p64" href="#p64">page 64</a>] (<a href="#Contents">Contents</a>)
- sequence between the " delimiters, the behavior is undefined.69) Header name
+ sequence between the " delimiters, the behavior is undefined.<sup><a href="#note69"><b>69)</b></a></sup> Header name
preprocessing tokens are recognized only within #include preprocessing directives and
- in implementation-defined locations within #pragma directives.70)
+ in implementation-defined locations within #pragma directives.<sup><a href="#note70"><b>70)</b></a></sup>
4 EXAMPLE The following sequence of characters:
0x3<1/a.h>1e2
#include <1/a.h>
constant token.
- 69) Thus, sequences of characters that resemble escape sequences cause undefined behavior.
-
70) For an example of a header name preprocessing token used in a #pragma directive, see <a href="#6.10.9">6.10.9</a>.
+ <sup><a name="note69" href="#note69"><b>69)</b></a></sup> Thus, sequences of characters that resemble escape sequences cause undefined behavior.
+
<sup><a name="note70" href="#note70"><b>70)</b></a></sup> For an example of a header name preprocessing token used in a #pragma directive, see <a href="#6.10.9">6.10.9</a>.
[<a name="p65" href="#p65">page 65</a>] (<a href="#Contents">Contents</a>)
<a name="6.4.9" href="#6.4.9"><b> 6.4.9 Comments</b></a>
1 Except within a character constant, a string literal, or a comment, the characters /*
introduce a comment. The contents of such a comment are examined only to identify
- multibyte characters and to find the characters */ that terminate it.71)
+ multibyte characters and to find the characters */ that terminate it.<sup><a href="#note71"><b>71)</b></a></sup>
2 Except within a character constant, a string literal, or a comment, the characters //
introduce a comment that includes all multibyte characters up to, but not including, the
next new-line character. The contents of such a comment are examined only to identify
- 71) Thus, /* ... */ comments do not nest.
+ <sup><a name="note71" href="#note71"><b>71)</b></a></sup> Thus, /* ... */ comments do not nest.
[<a name="p66" href="#p66">page 66</a>] (<a href="#Contents">Contents</a>)
value, or that designates an object or a function, or that generates side effects, or that
performs a combination thereof.
2 Between the previous and next sequence point an object shall have its stored value
- modified at most once by the evaluation of an expression.72) Furthermore, the prior value
- shall be read only to determine the value to be stored.73)
-3 The grouping of operators and operands is indicated by the syntax.74) Except as specified
+ modified at most once by the evaluation of an expression.<sup><a href="#note72"><b>72)</b></a></sup> Furthermore, the prior value
+ shall be read only to determine the value to be stored.<sup><a href="#note73"><b>73)</b></a></sup>
+3 The grouping of operators and operands is indicated by the syntax.<sup><a href="#note74"><b>74)</b></a></sup> Except as specified
later (for the function-call (), &&, ||, ?:, and comma operators), the order of evaluation
of subexpressions and the order in which side effects take place are both unspecified.
4 Some operators (the unary operator ~, and the binary operators <<, >>, &, ^, and |,
result is not mathematically defined or not in the range of representable values for its
type), the behavior is undefined.
6 The effective type of an object for an access to its stored value is the declared type of the
- object, if any.75) If a value is stored into an object having no declared type through an
+ object, if any.<sup><a href="#note75"><b>75)</b></a></sup> If a value is stored into an object having no declared type through an
lvalue having a type that is not a character type, then the type of the lvalue becomes the
- 72) A floating-point status flag is not an object and can be set more than once within an expression.
- 73) This paragraph renders undefined statement expressions such as
+ <sup><a name="note72" href="#note72"><b>72)</b></a></sup> A floating-point status flag is not an object and can be set more than once within an expression.
+ <sup><a name="note73" href="#note73"><b>73)</b></a></sup> This paragraph renders undefined statement expressions such as
i = ++i + 1;
a[i++] = i;
while allowing
i = i + 1;
a[i] = i;
- 74) The syntax specifies the precedence of operators in the evaluation of an expression, which is the same
+ <sup><a name="note74" href="#note74"><b>74)</b></a></sup> The syntax specifies the precedence of operators in the evaluation of an expression, which is the same
as the order of the major subclauses of this subclause, highest precedence first. Thus, for example, the
expressions allowed as the operands of the binary + operator (<a href="#6.5.6">6.5.6</a>) are those expressions defined in
<a href="#6.5.1">6.5.1</a> through <a href="#6.5.6">6.5.6</a>. The exceptions are cast expressions (<a href="#6.5.4">6.5.4</a>) as operands of unary operators
the conditional operator ?: (<a href="#6.5.15">6.5.15</a>).
Within each major subclause, the operators have the same precedence. Left- or right-associativity is
indicated in each subclause by the syntax for the expressions discussed therein.
- 75) Allocated objects have no declared type.
+ <sup><a name="note75" href="#note75"><b>75)</b></a></sup> Allocated objects have no declared type.
[<a name="p67" href="#p67">page 67</a>] (<a href="#Contents">Contents</a>)
all other accesses to an object having no declared type, the effective type of the object is
simply the type of the lvalue used for the access.
7 An object shall have its stored value accessed only by an lvalue expression that has one of
- the following types:76)
+ the following types:<sup><a href="#note76"><b>76)</b></a></sup>
-- a type compatible with the effective type of the object,
-- a qualified version of a type compatible with the effective type of the object,
-- a type that is the signed or unsigned type corresponding to the effective type of the
-- a character type.
8 A floating expression may be contracted, that is, evaluated as though it were an atomic
operation, thereby omitting rounding errors implied by the source code and the
- expression evaluation method.
77) The FP_CONTRACT pragma in <a href="#7.12"><math.h></a> provides a
+ expression evaluation method.
<sup><a href="#note77"><b>77)</b></a></sup> The FP_CONTRACT pragma in <a href="#7.12"><math.h></a> provides a
way to disallow contracted expressions. Otherwise, whether and how expressions are
- contracted is implementation-defined.78)
+ contracted is implementation-defined.<sup><a href="#note78"><b>78)</b></a></sup>
Forward references: the FP_CONTRACT pragma (<a href="#7.12.2">7.12.2</a>), copying functions (<a href="#7.21.2">7.21.2</a>).
- 76) The intent of this list is to specify those circumstances in which an object may or may not be aliased.
- 77) A contracted expression might also omit the raising of floating-point exceptions.
- 78) This license is specifically intended to allow implementations to exploit fast machine instructions that
+ <sup><a name="note76" href="#note76"><b>76)</b></a></sup> The intent of this list is to specify those circumstances in which an object may or may not be aliased.
+ <sup><a name="note77" href="#note77"><b>77)</b></a></sup> A contracted expression might also omit the raising of floating-point exceptions.
+ <sup><a name="note78" href="#note78"><b>78)</b></a></sup> This license is specifically intended to allow implementations to exploit fast machine instructions that
combine multiple C operators. As contractions potentially undermine predictability, and can even
decrease accuracy for containing expressions, their use needs to be well-defined and clearly
documented.
<b> Semantics</b>
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).79)
+ designator).<sup><a href="#note79"><b>79)</b></a></sup>
3 A constant is a primary expression. Its type depends on its form and value, as detailed in
<a href="#6.4.4">6.4.4</a>.
4 A string literal is a primary expression. It is an lvalue with type as detailed in <a href="#6.4.5">6.4.5</a>.
- 79) Thus, an undeclared identifier is a violation of the syntax.
+ <sup><a name="note79" href="#note79"><b>79)</b></a></sup> Thus, an undeclared identifier is a violation of the syntax.
[<a name="p69" href="#p69">page 69</a>] (<a href="#Contents">Contents</a>)
<a name="6.5.2.2" href="#6.5.2.2"><b> 6.5.2.2 Function calls</b></a>
<b> Constraints</b>
-1 The expression that denotes the called function80) shall have type pointer to function
+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.
2 If the expression that denotes the called function has a type that includes a prototype, the
number of arguments shall agree with the number of parameters. Each argument shall
function. The list of expressions specifies the arguments to the function.
4 An argument may be an expression of any object type. In preparing for the call to a
function, the arguments are evaluated, and each parameter is assigned the value of the
- corresponding argument.81)
+ corresponding argument.<sup><a href="#note81"><b>81)</b></a></sup>
5 If the expression that denotes the called function has type pointer to function returning an
object type, the function call expression has the same type as that object type, and has the
value determined as specified in <a href="#6.8.6.4">6.8.6.4</a>. Otherwise, the function call has type void. If
- 80) Most often, this is the result of converting an identifier that is a function designator.
- 81) A function may change the values of its parameters, but these changes cannot affect the values of the
+ <sup><a name="note80" href="#note80"><b>80)</b></a></sup> Most often, this is the result of converting an identifier that is a function designator.
+ <sup><a name="note81" href="#note81"><b>81)</b></a></sup> A function may change the values of its parameters, but these changes cannot affect the values of the
arguments. On the other hand, it is possible to pass a pointer to an object, and the function may
change the value of the object pointed to. A parameter declared to have array or function type is
adjusted to have a pointer type as described in <a href="#6.9.1">6.9.1</a>.
<b> Semantics</b>
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,82) and is an lvalue if
+ 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
the first expression is an lvalue. If the first expression has qualified type, the result has
the so-qualified version of the type of the designated member.
4 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 of the object to
- which the first expression points, and is an lvalue.83) If the first expression is a pointer to
+ which the first expression points, and is an lvalue.<sup><a href="#note83"><b>83)</b></a></sup> If the first expression is a pointer to
a qualified type, the result has the so-qualified version of the type of the designated
member.
5 One special guarantee is made in order to simplify the use of unions: if a union contains
- 82) If the member used to access the contents of a union object is not the same as the member last used to
+ <sup><a name="note82" href="#note82"><b>82)</b></a></sup> 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
punning"). This might be a trap representation.
- 83) If &E is a valid pointer expression (where & is the ''address-of '' operator, which generates a pointer to
+ <sup><a name="note83" href="#note83"><b>83)</b></a></sup> If &E is a valid pointer expression (where & is the ''address-of '' operator, which generates a pointer to
its operand), the expression (&E)->MOS is the same as E.MOS.
[<a name="p73" href="#p73">page 73</a>] (<a href="#Contents">Contents</a>)
<b> Semantics</b>
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
- value is given by the initializer list.84)
+ value is given by the initializer list.<sup><a href="#note84"><b>84)</b></a></sup>
5 If the type name specifies an array of unknown size, the size is determined by the
initializer list as specified in <a href="#6.7.8">6.7.8</a>, and the type of the compound literal is that of the
completed array type. Otherwise (when the type name specifies an object type), the type
lvalue.
- 84) Note that this differs from a cast expression. For example, a cast specifies a conversion to scalar types
+ <sup><a name="note84" href="#note84"><b>84)</b></a></sup> 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.
[<a name="p75" href="#p75">page 75</a>] (<a href="#Contents">Contents</a>)
has static storage duration; otherwise, it has automatic storage duration associated with
the enclosing block.
7 All the semantic rules and constraints for initializer lists in <a href="#6.7.8">6.7.8</a> are applicable to
- compound literals.85)
+ compound literals.<sup><a href="#note85"><b>85)</b></a></sup>
8 String literals, and compound literals with const-qualified types, need not designate
- distinct objects.86)
+ distinct objects.<sup><a href="#note86"><b>86)</b></a></sup>
9 EXAMPLE 1 The file scope definition
int *p = (int []){2, 4};
initializes p to point to the first element of an array of two ints, the first having the value two and the
- 85) For example, subobjects without explicit initializers are initialized to zero.
- 86) This allows implementations to share storage for string literals and constant compound literals with
+ <sup><a name="note85" href="#note85"><b>85)</b></a></sup> For example, subobjects without explicit initializers are initialized to zero.
+ <sup><a name="note86" href="#note86"><b>86)</b></a></sup> This allows implementations to share storage for string literals and constant compound literals with
the same or overlapping representations.
[<a name="p76" href="#p76">page 76</a>] (<a href="#Contents">Contents</a>)
a function designator; if it points to an object, the result is an lvalue designating the
object. If the operand has type ''pointer to type'', the result has type ''type''. If an
invalid value has been assigned to the pointer, the behavior of the unary * operator is
- undefined.87)
+ undefined.<sup><a href="#note87"><b>87)</b></a></sup>
Forward references: 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>).
<a name="6.5.3.3" href="#6.5.3.3"><b> 6.5.3.3 Unary arithmetic operators</b></a>
- 87) Thus, &*E is equivalent to E (even if E is a null pointer), and &(E1[E2]) to ((E1)+(E2)). It is
+ <sup><a name="note87" href="#note87"><b>87)</b></a></sup> 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
an object pointer type, *(T)P is an lvalue that has a type compatible with that to which T points.
integer constant.
3 When applied to an operand that has type char, unsigned char, or signed char,
(or a qualified version thereof) the result is 1. When applied to an operand that has array
- type, the result is the total number of bytes in the array.88) When applied to an operand
+ type, the result is the total number of bytes in the array.<sup><a href="#note88"><b>88)</b></a></sup> When applied to an operand
that has structure or union type, the result is the total number of bytes in such an object,
including internal and trailing padding.
4 The value of the result is implementation-defined, and its type (an unsigned integer type)
- 88) When applied to a parameter declared to have array or function type, the sizeof operator yields the
+ <sup><a name="note88" href="#note88"><b>88)</b></a></sup> 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>).
[<a name="p80" href="#p80">page 80</a>] (<a href="#Contents">Contents</a>)
<a href="#6.5.16.1">6.5.16.1</a>, shall be specified by means of an explicit cast.
<b> Semantics</b>
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.89) A cast that specifies
+ expression to the named type. This construction is called a cast.<sup><a href="#note89"><b>89)</b></a></sup> A cast that specifies
no conversion has no effect on the type or value of an expression.
5 If the value of the expression is represented with greater precision or range than required
by the type named by the cast (<a href="#6.3.1.8">6.3.1.8</a>), then the cast specifies a conversion even if the
- 89) A cast does not yield an lvalue. Thus, a cast to a qualified type has the same effect as a cast to the
+ <sup><a name="note89" href="#note89"><b>89)</b></a></sup> 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.
[<a name="p81" href="#p81">page 81</a>] (<a href="#Contents">Contents</a>)
second; the result of the % operator is the remainder. In both operations, if the value of
the second operand is zero, the behavior is undefined.
6 When integers are divided, the result of the / operator is the algebraic quotient with any
- fractional part discarded.90) If the quotient a/b is representable, the expression
+ fractional part discarded.<sup><a href="#note90"><b>90)</b></a></sup> If the quotient a/b is representable, the expression
(a/b)*b + a%b shall equal a.
<a name="6.5.6" href="#6.5.6"><b> 6.5.6 Additive operators</b></a>
<b> Syntax</b>
- 90) This is often called ''truncation toward zero''.
+ <sup><a name="note90" href="#note90"><b>90)</b></a></sup> This is often called ''truncation toward zero''.
[<a name="p82" href="#p82">page 82</a>] (<a href="#Contents">Contents</a>)
value as ((Q)-(P))+1 and as -((P)-((Q)+1)), and has the value zero if the
expression P points one past the last element of the array object, even though the
- expression (Q)+1 does not point to an element of the array object.91)
+ expression (Q)+1 does not point to an element of the array object.<sup><a href="#note91"><b>91)</b></a></sup>
10 EXAMPLE Pointer arithmetic is well defined with pointers to variable length array types.
{
int n = 4, m = 3;
- 91) Another way to approach pointer arithmetic is first to convert the pointer(s) to character pointer(s): In
+ <sup><a name="note91" href="#note91"><b>91)</b></a></sup> 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
original type. For pointer subtraction, the result of the difference between the character pointers is
last element of the same array object, the pointer expression Q+1 compares greater than
P. In all other cases, the behavior is undefined.
6 Each of the operators < (less than), > (greater than), <= (less than or equal to), and >=
- (greater than or equal to) shall yield 1 if the specified relation is true and 0 if it is false.92)
+ (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.
<a name="6.5.9" href="#6.5.9"><b> 6.5.9 Equality operators</b></a>
<b> Syntax</b>
-- one operand is a pointer and the other is a null pointer constant.
<b> Semantics</b>
3 The == (equal to) and != (not equal to) operators are analogous to the relational
- operators except for their lower precedence.93) Each of the operators yields 1 if the
+ operators except for their lower precedence.<sup><a href="#note93"><b>93)</b></a></sup> Each of the operators yields 1 if the
specified relation is true and 0 if it is false. The result has type int. For any pair of
operands, exactly one of the relations is true.
4 If both of the operands have arithmetic type, the usual arithmetic conversions are
(complex) result type determined by the usual arithmetic conversions are equal.
- 92) The expression a<b<c is not interpreted as in ordinary mathematics. As the syntax indicates, it
+ <sup><a name="note92" href="#note92"><b>92)</b></a></sup> 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''.
- 93) Because of the precedences, a<b == c<d is 1 whenever a<b and c<d have the same truth-value.
+ <sup><a name="note93" href="#note93"><b>93)</b></a></sup> Because of the precedences, a<b == c<d is 1 whenever a<b and c<d have the same truth-value.
[<a name="p86" href="#p86">page 86</a>] (<a href="#Contents">Contents</a>)
both are pointers to one past the last element of the same array object, or one is a pointer
to one past the end of one array object and the other is a pointer to the start of a different
array object that happens to immediately follow the first array object in the address
- space.94)
+ space.<sup><a href="#note94"><b>94)</b></a></sup>
7 For the purposes of these operators, a pointer to an object that is not an element of an
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.
- 94) Two objects may be adjacent in memory because they are adjacent elements of a larger array or
+ <sup><a name="note94" href="#note94"><b>94)</b></a></sup> Two objects may be adjacent in memory because they are adjacent elements of a larger array or
adjacent members of a structure with no padding between them, or because the implementation chose
to place them so, even though they are unrelated. If prior invalid pointer operations (such as accesses
outside array bounds) produced undefined behavior, subsequent comparisons also produce undefined
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
only if the first compares equal to 0; the result is the value of the second or third operand
- (whichever is evaluated), converted to the type described below.95) If an attempt is made
+ (whichever is evaluated), converted to the type described below.<sup><a href="#note95"><b>95)</b></a></sup> If an attempt is made
to modify the result of a conditional operator or to access it after the next sequence point,
the behavior is undefined.
5 If both the second and third operands have arithmetic type, the result type that would be
null pointer constant, the result has the type of the other operand; otherwise, one operand
is a pointer to void or a qualified version of void, in which case the result type is a
- 95) A conditional expression does not yield an lvalue.
+ <sup><a name="note95" href="#note95"><b>95)</b></a></sup> A conditional expression does not yield an lvalue.
[<a name="p90" href="#p90">page 90</a>] (<a href="#Contents">Contents</a>)
<a name="6.5.16.1" href="#6.5.16.1"><b> 6.5.16.1 Simple assignment</b></a>
<b> Constraints</b>
-1 One of the following shall hold:96)
+1 One of the following shall hold:<sup><a href="#note96"><b>96)</b></a></sup>
-- the left operand has qualified or unqualified arithmetic type and the right has
arithmetic type;
-- the left operand has a qualified or unqualified version of a structure or union type
- 96) The asymmetric appearance of these constraints with respect to type qualifiers is due to the conversion
+ <sup><a name="note96" href="#note96"><b>96)</b></a></sup> 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
not volatile from the type int volatile * const).
<b> Semantics</b>
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
- type and value.97) If an attempt is made to modify the result of a comma operator or to
+ type and value.<sup><a href="#note97"><b>97)</b></a></sup> If an attempt is made to modify the result of a comma operator or to
access it after the next sequence point, the behavior is undefined.
3 EXAMPLE As indicated by the syntax, the comma operator (as described in this subclause) cannot
appear in contexts where a comma is used to separate items in a list (such as arguments to functions or lists
- 97) A comma operator does not yield an lvalue.
+ <sup><a name="note97" href="#note97"><b>97)</b></a></sup> A comma operator does not yield an lvalue.
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<b> Constraints</b>
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
- evaluated.98)
+ evaluated.<sup><a href="#note98"><b>98)</b></a></sup>
4 Each constant expression shall evaluate to a constant that is in the range of representable
values for its type.
<b> Semantics</b>
expression is evaluated in the translation environment, the arithmetic precision and range
shall be at least as great as if the expression were being evaluated in the execution
environment.
-6 An integer constant expression99) shall have integer type and shall only have operands
+6 An integer constant expression<sup><a href="#note99"><b>99)</b></a></sup> shall have integer type and shall only have operands
that are integer constants, enumeration constants, character constants, sizeof
expressions whose results are integer constants, and floating constants that are the
immediate operands of casts. Cast operators in an integer constant expression shall only
-
98) The operand of a sizeof operator is usually not evaluated (<a href="#6.5.3.4">6.5.3.4</a>).
- 99) An integer constant expression is used to specify the size of a bit-field member of a structure, the
+
<sup><a name="note98" href="#note98"><b>98)</b></a></sup> The operand of a sizeof operator is usually not evaluated (<a href="#6.5.3.4">6.5.3.4</a>).
+ <sup><a name="note99" href="#note99"><b>99)</b></a></sup> An integer constant expression is used to specify the size of a bit-field member of a structure, the
value of an enumeration constant, the size of an array, or the value of a case constant. Further
constraints that apply to the integer constant expressions used in conditional-inclusion preprocessing
directives are discussed in <a href="#6.10.1">6.10.1</a>.
accessed by use of these operators.
10 An implementation may accept other forms of constant expressions.
11 The semantic rules for the evaluation of a constant expression are the same as for
- nonconstant expressions.100)
+ nonconstant expressions.<sup><a href="#note100"><b>100)</b></a></sup>
Forward references: array declarators (<a href="#6.7.5.2">6.7.5.2</a>), initialization (<a href="#6.7.8">6.7.8</a>).
- 100) Thus, in the following initialization,
+ <sup><a name="note100" href="#note100"><b>100)</b></a></sup> Thus, in the following initialization,
static int i = 2 || 1 / 0;
the expression is a valid integer constant expression with value one.
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:
-- for an object, causes storage to be reserved for that object;
- -- for a function, includes the function body;101)
+ -- for a function, includes the function body;<sup><a href="#note101"><b>101)</b></a></sup>
-- for an enumeration constant or typedef name, is the (only) declaration of the
identifier.
6 The declaration specifiers consist of a sequence of specifiers that indicate the linkage,
storage duration, and part of the type of the entities that the declarators denote. The init-
declarator-list is a comma-separated sequence of declarators, each of which may have
-
101) Function definitions have a different syntax, described in <a href="#6.9.1">6.9.1</a>.
+
<sup><a name="note101" href="#note101"><b>101)</b></a></sup> Function definitions have a different syntax, described in <a href="#6.9.1">6.9.1</a>.
[<a name="p97" href="#p97">page 97</a>] (<a href="#Contents">Contents</a>)
register
<b> Constraints</b>
2 At most, one storage-class specifier may be given in the declaration specifiers in a
- declaration.102)
+ declaration.<sup><a href="#note102"><b>102)</b></a></sup>
<b> Semantics</b>
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
were discussed in <a href="#6.2.2">6.2.2</a> and <a href="#6.2.4">6.2.4</a>.
4 A declaration of an identifier for an object with storage-class specifier register
suggests that access to the object be as fast as possible. The extent to which such
- suggestions are effective is implementation-defined.103)
+ suggestions are effective is implementation-defined.<sup><a href="#note103"><b>103)</b></a></sup>
5 The declaration of an identifier for a function that has block scope shall have no explicit
storage-class specifier other than extern.
-
102) See ''future language directions'' (<a href="#6.11.5">6.11.5</a>).
- 103) The implementation may treat any register declaration simply as an auto declaration. However,
+
<sup><a name="note102" href="#note102"><b>102)</b></a></sup> See ''future language directions'' (<a href="#6.11.5">6.11.5</a>).
+ <sup><a name="note103" href="#note103"><b>103)</b></a></sup> The implementation may treat any register declaration simply as an auto declaration. However,
whether or not addressable storage is actually used, the address of any part of an object declared with
storage-class specifier register cannot be computed, either explicitly (by use of the unary &
operator as discussed in <a href="#6.5.3.2">6.5.3.2</a>) or implicitly (by converting an array name to a pointer as discussed in
-- enum specifier
-- typedef name
3 The type specifier _Complex shall not be used if the implementation does not provide
- complex types.104)
+ complex types.<sup><a href="#note104"><b>104)</b></a></sup>
<b> Semantics</b>
4 Specifiers for structures, unions, and enumerations are discussed in <a href="#6.7.2.1">6.7.2.1</a> through
<a name="6.7.2.3" href="#6.7.2.3"><b> 6.7.2.3. Declarations of typedef names are discussed in 6.7.7. The characteristics of the</b></a>
- 104) Freestanding implementations are not required to provide complex types. *
+ <sup><a name="note104" href="#note104"><b>104)</b></a></sup> Freestanding implementations are not required to provide complex types. *
[<a name="p100" href="#p100">page 100</a>] (<a href="#Contents">Contents</a>)
members, the behavior is undefined. The type is incomplete until after the } that
terminates the list.
8 A member of a structure or union may have any object type other than a variably
- modified type.105) In addition, a member may be declared to consist of a specified
- number of bits (including a sign bit, if any). Such a member is called a bit-field;106) its
+ modified type.<sup><a href="#note105"><b>105)</b></a></sup> In addition, a member may be declared to consist of a specified
+ number of bits (including a sign bit, if any). Such a member is called a bit-field;<sup><a href="#note106"><b>106)</b></a></sup> its
width is preceded by a colon.
9 A bit-field is interpreted as a signed or unsigned integer type consisting of the specified
- number of bits.107) If the value 0 or 1 is stored into a nonzero-width bit-field of type
+ number of bits.<sup><a href="#note107"><b>107)</b></a></sup> If the value 0 or 1 is stored into a nonzero-width bit-field of type
_Bool, the value of the bit-field shall compare equal to the value stored.
10 An implementation may allocate any addressable storage unit large enough to hold a bit-
field. If enough space remains, a bit-field that immediately follows another bit-field in a
low-order or low-order to high-order) is implementation-defined. The alignment of the
addressable storage unit is unspecified.
11 A bit-field declaration with no declarator, but only a colon and a width, indicates an
- unnamed bit-field.108) As a special case, a bit-field structure member with a width of 0
+ unnamed bit-field.<sup><a href="#note108"><b>108)</b></a></sup> As a special case, a bit-field structure member with a width of 0
indicates that no further bit-field is to be packed into the unit in which the previous bit-
field, if any, was placed.
- 105) A structure or union can not contain a member with a variably modified type because member names
+ <sup><a name="note105" href="#note105"><b>105)</b></a></sup> 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>.
- 106) The unary & (address-of) operator cannot be applied to a bit-field object; thus, there are no pointers to
+ <sup><a name="note106" href="#note106"><b>106)</b></a></sup> The unary & (address-of) operator cannot be applied to a bit-field object; thus, there are no pointers to
or arrays of bit-field objects.
-
107) As specified in <a href="#6.7.2">6.7.2</a> above, if the actual type specifier used is int or a typedef-name defined as int,
+
<sup><a name="note107" href="#note107"><b>107)</b></a></sup> As specified in <a href="#6.7.2">6.7.2</a> above, if the actual type specifier used is int or a typedef-name defined as int,
then it is implementation-defined whether the bit-field is signed or unsigned.
- 108) An unnamed bit-field structure member is useful for padding to conform to externally imposed
+ <sup><a name="note108" href="#note108"><b>108)</b></a></sup> An unnamed bit-field structure member is useful for padding to conform to externally imposed
layouts.
[<a name="p102" href="#p102">page 102</a>] (<a href="#Contents">Contents</a>)
constant expression that has a value representable as an int.
<b> Semantics</b>
3 The identifiers in an enumerator list are declared as constants that have type int and
- may appear wherever such are permitted.109) An enumerator with = defines its
+ may appear wherever such are permitted.<sup><a href="#note109"><b>109)</b></a></sup> An enumerator with = defines its
enumeration constant as the value of the constant expression. If the first enumerator has
no =, the value of its enumeration constant is 0. Each subsequent enumerator with no =
defines its enumeration constant as the value of the constant expression obtained by
= may produce enumeration constants with values that duplicate other values in the same
enumeration.) The enumerators of an enumeration are also known as its members.
4 Each enumerated type shall be compatible with char, a signed integer type, or an
- unsigned integer type. The choice of type is implementation-defined,110) but shall be
+ unsigned integer type. The choice of type is implementation-defined,<sup><a href="#note110"><b>110)</b></a></sup> but shall be
capable of representing the values of all the members of the enumeration. The
enumerated type is incomplete until after the } that terminates the list of enumerator
declarations.
- 109) Thus, the identifiers of enumeration constants declared in the same scope shall all be distinct from
+ <sup><a name="note109" href="#note109"><b>109)</b></a></sup> 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.
- 110) An implementation may delay the choice of which integer type until all enumeration constants have
+ <sup><a name="note110" href="#note110"><b>110)</b></a></sup> An implementation may delay the choice of which integer type until all enumeration constants have
been seen.
[<a name="p105" href="#p105">page 105</a>] (<a href="#Contents">Contents</a>)
without an enumerator list shall only appear after the type it specifies is complete.
<b> Semantics</b>
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 incomplete111) until the closing brace
+ 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
of the list defining the content, and complete thereafter.
5 Two declarations of structure, union, or enumerated types which are in different scopes or
use different tags declare distinct types. Each declaration of a structure, union, or
enum identifier { enumerator-list , }
declares a structure, union, or enumerated type. The list defines the structure content,
- 111) An incomplete type may only by used when the size of an object of that type is not needed. It is not
+ <sup><a name="note111" href="#note111"><b>111)</b></a></sup> 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
in <a href="#6.2.5">6.2.5</a>.) The specification has to be complete before such a function is called or defined.
[<a name="p106" href="#p106">page 106</a>] (<a href="#Contents">Contents</a>)
- union content, or enumeration content. If an identifier is provided,112) the type specifier
+ union content, or enumeration content. If an identifier is provided,<sup><a href="#note112"><b>112)</b></a></sup> the type specifier
also declares the identifier to be the tag of that type.
7 A declaration of the form
struct-or-union identifier ;
- specifies a structure or union type and declares the identifier as a tag of that type.113)
+ 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>
8 If a type specifier of the form
struct-or-union identifier
occurs other than as part of one of the above forms, and no other declaration of the
- 112) If there is no identifier, the type can, within the translation unit, only be referred to by the declaration
+ <sup><a name="note112" href="#note112"><b>112)</b></a></sup> If there is no identifier, the type can, within the translation unit, only be referred to by the declaration
of which it is a part. Of course, when the declaration is of a typedef name, subsequent declarations
can make use of that typedef name to declare objects having the specified structure, union, or
enumerated type.
- 113) A similar construction with enum does not exist.
+ <sup><a name="note113" href="#note113"><b>113)</b></a></sup> A similar construction with enum does not exist.
[<a name="p107" href="#p107">page 107</a>] (<a href="#Contents">Contents</a>)
restrict-qualified.
<b> Semantics</b>
3 The properties associated with qualified types are meaningful only for expressions that
- are lvalues.114)
+ are lvalues.<sup><a href="#note114"><b>114)</b></a></sup>
4 If the same qualifier appears more than once in the same specifier-qualifier-list, either
directly or via one or more typedefs, the behavior is the same as if it appeared only
once.
- 114) The implementation may place a const object that is not volatile in a read-only region of
+ <sup><a name="note114" href="#note114"><b>114)</b></a></sup> 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.
5 If an attempt is made to modify an object defined with a const-qualified type through use
of an lvalue with non-const-qualified type, the behavior is undefined. If an attempt is
made to refer to an object defined with a volatile-qualified type through use of an lvalue
- with non-volatile-qualified type, the behavior is undefined.115)
+ with non-volatile-qualified type, the behavior is undefined.<sup><a href="#note115"><b>115)</b></a></sup>
6 An object that has volatile-qualified type may be modified in ways unknown to the
implementation or have other unknown side effects. Therefore any expression referring
to such an object shall be evaluated strictly according to the rules of the abstract machine,
as described in <a href="#5.1.2.3">5.1.2.3</a>. Furthermore, at every sequence point the value last stored in the
object shall agree with that prescribed by the abstract machine, except as modified by the
- unknown factors mentioned previously.116) What constitutes an access to an object that
+ unknown factors mentioned previously.<sup><a href="#note116"><b>116)</b></a></sup> What constitutes an access to an object that
has volatile-qualified type is implementation-defined.
7 An object that is accessed through a restrict-qualified pointer has a special association
with that pointer. This association, defined in <a href="#6.7.3.1">6.7.3.1</a> below, requires that all accesses to
- that object use, directly or indirectly, the value of that particular pointer.117) The intended
+ that object use, directly or indirectly, the value of that particular pointer.<sup><a href="#note117"><b>117)</b></a></sup> The intended
use of the restrict qualifier (like the register storage class) is to promote
optimization, and deleting all instances of the qualifier from all preprocessing translation
units composing a conforming program does not change its meaning (i.e., observable
behavior).
8 If the specification of an array type includes any type qualifiers, the element type is so-
qualified, not the array type. If the specification of a function type includes any type
- qualifiers, the behavior is undefined.118)
+ qualifiers, the behavior is undefined.<sup><a href="#note118"><b>118)</b></a></sup>
9 For two qualified types to be compatible, both shall have the identically qualified version
of a compatible type; the order of type qualifiers within a list of specifiers or qualifiers
does not affect the specified type.
- 115) This applies to those objects that behave as if they were defined with qualified types, even if they are
+ <sup><a name="note115" href="#note115"><b>115)</b></a></sup> This applies to those objects that behave as if they were defined with qualified types, even if they are
never actually defined as objects in the program (such as an object at a memory-mapped input/output
address).
- 116) A volatile declaration may be used to describe an object corresponding to a memory-mapped
+ <sup><a name="note116" href="#note116"><b>116)</b></a></sup> A volatile declaration may be used to describe an object corresponding to a memory-mapped
input/output port or an object accessed by an asynchronously interrupting function. Actions on
objects so declared shall not be ''optimized out'' by an implementation or reordered except as
permitted by the rules for evaluating expressions.
- 117) For example, a statement that assigns a value returned by malloc to a single pointer establishes this
+ <sup><a name="note117" href="#note117"><b>117)</b></a></sup> For example, a statement that assigns a value returned by malloc to a single pointer establishes this
association between the allocated object and the pointer.
- 118) Both of these can occur through the use of typedefs.
+ <sup><a name="note118" href="#note118"><b>118)</b></a></sup> Both of these can occur through the use of typedefs.
[<a name="p109" href="#p109">page 109</a>] (<a href="#Contents">Contents</a>)
whatever function is called at program startup in a freestanding environment).
3 In what follows, a pointer expression E is said to be based on object P if (at some
sequence point in the execution of B prior to the evaluation of E) modifying P to point to
- a copy of the array object into which it formerly pointed would change the value of E.119)
+ a copy of the array object into which it formerly pointed would change the value of E.<sup><a href="#note119"><b>119)</b></a></sup>
Note that ''based'' is defined only for expressions with pointer types.
4 During each execution of B, let L be any lvalue that has &L based on P. If L is used to
access the value of the object X that it designates, and X is also modified (by any means),
5 Here an execution of B means that portion of the execution of the program that would
correspond to the lifetime of an object with scalar type and automatic storage duration
- 119) In other words, E depends on the value of P itself rather than on the value of an object referenced
+ <sup><a name="note119" href="#note119"><b>119)</b></a></sup> In other words, E depends on the value of P itself rather than on the value of an object referenced
indirectly through P. For example, if identifier p has type (int **restrict), then the pointer
expressions p and p+1 are based on the restricted pointer object designated by p, but the pointer
expressions *p and p[1] are not.
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
only once. Making a function an inline function suggests that calls to the function be as
- fast as possible.120) The extent to which such suggestions are effective is
- implementation-defined.121)
+ fast as possible.<sup><a href="#note120"><b>120)</b></a></sup> The extent to which such suggestions are effective is
+ implementation-defined.<sup><a href="#note121"><b>121)</b></a></sup>
6 Any function with internal linkage can be an inline function. For a function with external
linkage, the following restrictions apply: If a function is declared with an inline
[<a name="p112" href="#p112">page 112</a>] (<a href="#Contents">Contents</a>)
and does not forbid an external definition in another translation unit. An inline definition
provides an alternative to an external definition, which a translator may use to implement
any call to the function in the same translation unit. It is unspecified whether a call to the
- function uses the inline definition or the external definition.122)
+ function uses the inline definition or the external definition.<sup><a href="#note122"><b>122)</b></a></sup>
7 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.
Forward references: function definitions (<a href="#6.9.1">6.9.1</a>).
- 120) By using, for example, an alternative to the usual function call mechanism, such as ''inline
+ <sup><a name="note120" href="#note120"><b>120)</b></a></sup> 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
definition it had at the point the function body appears, and not where the function is called; and
identifiers refer to the declarations in scope where the body occurs. Likewise, the function has a
single address, regardless of the number of inline definitions that occur in addition to the external
definition.
- 121) For example, an implementation might never perform inline substitution, or might only perform inline
+ <sup><a name="note121" href="#note121"><b>121)</b></a></sup> For example, an implementation might never perform inline substitution, or might only perform inline
substitutions to calls in the scope of an inline declaration.
- 122) Since an inline definition is distinct from the corresponding external definition and from any other
+ <sup><a name="note122" href="#note122"><b>122)</b></a></sup> Since an inline definition is distinct from the corresponding external definition and from any other
corresponding inline definitions in other translation units, all corresponding objects with static storage
duration are also distinct in each of the definitions.
D[ type-qualifier-list static assignment-expression ]
D[ type-qualifier-listopt * ]
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
- T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.123)
+ 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.)
4 If the size is not present, the array type is an incomplete type. If the size is * instead of
being an expression, the array type is a variable length array type of unspecified size,
- which can only be used in declarations with function prototype scope;124) such arrays are
+ which can only be used in declarations with function prototype scope;<sup><a href="#note124"><b>124)</b></a></sup> such arrays are
nonetheless complete types. If the size is an integer constant expression and the element
- 123) When several ''array of'' specifications are adjacent, a multidimensional array is declared.
+ <sup><a name="note123" href="#note123"><b>123)</b></a></sup> When several ''array of'' specifications are adjacent, a multidimensional array is declared.
[<a name="p116" href="#p116">page 116</a>] (<a href="#Contents">Contents</a>)
-
124) Thus, * can be used only in function declarations that are not definitions (see <a href="#6.7.5.3">6.7.5.3</a>).
+
<sup><a name="note124" href="#note124"><b>124)</b></a></sup> Thus, * can be used only in function declarations that are not definitions (see <a href="#6.7.5.3">6.7.5.3</a>).
[<a name="p117" href="#p117">page 117</a>] (<a href="#Contents">Contents</a>)
8 A declaration of a parameter as ''function returning type'' shall be adjusted to ''pointer to
function returning type'', as in <a href="#6.3.2.1">6.3.2.1</a>.
9 If the list terminates with an ellipsis (, ...), no information about the number or types
- of the parameters after the comma is supplied.125)
+ of the parameters after the comma is supplied.<sup><a href="#note125"><b>125)</b></a></sup>
10 The special case of an unnamed parameter of type void as the only item in the list
specifies that the function has no parameters.
11 If, in a parameter declaration, an identifier can be treated either as a typedef name or as a
list in a function declarator that is part of a definition of that function specifies that the
function has no parameters. The empty list in a function declarator that is not part of a
definition of that function specifies that no information about the number or types of the
- parameters is supplied.126)
-15 For two function types to be compatible, both shall specify compatible return types.127)
+ parameters is supplied.<sup><a href="#note126"><b>126)</b></a></sup>
+15 For two function types to be compatible, both shall specify compatible return types.<sup><a href="#note127"><b>127)</b></a></sup>
-
125) 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
+
<sup><a name="note125" href="#note125"><b>125)</b></a></sup> 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.
-
126) See ''future language directions'' (<a href="#6.11.6">6.11.6</a>).
- 127) If both function types are ''old style'', parameter types are not compared.
+
<sup><a name="note126" href="#note126"><b>126)</b></a></sup> See ''future language directions'' (<a href="#6.11.6">6.11.6</a>).
+ <sup><a name="note127" href="#note127"><b>127)</b></a></sup> If both function types are ''old style'', parameter types are not compared.
[<a name="p119" href="#p119">page 119</a>] (<a href="#Contents">Contents</a>)
<b> Semantics</b>
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
- omits the identifier.128)
+ omits the identifier.<sup><a href="#note128"><b>128)</b></a></sup>
3 EXAMPLE The constructions
(a) int
(b) int *
- 128) As indicated by the syntax, empty parentheses in a type name are interpreted as ''function with no
+ <sup><a name="note128" href="#note128"><b>128)</b></a></sup> 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.
[<a name="p122" href="#p122">page 122</a>] (<a href="#Contents">Contents</a>)
to the type of the current object: array elements in increasing subscript order, structure
[<a name="p126" href="#p126">page 126</a>] (<a href="#Contents">Contents</a>)
- members in declaration order, and the first named member of a union.129) In contrast, a
+ members in declaration order, and the first named member of a union.<sup><a href="#note129"><b>129)</b></a></sup> In contrast, a
designation causes the following initializer to begin initialization of the subobject
described by the designator. Initialization then continues forward in order, beginning
- with the next subobject after that described by the designator.130)
+ with the next subobject after that described by the designator.<sup><a href="#note130"><b>130)</b></a></sup>
18 Each designator list begins its description with the current object associated with the
closest surrounding brace pair. Each item in the designator list (in order) specifies a
particular member of its current object and changes the current object for the next
- designator (if any) to be that member.131) The current object that results at the end of the
+ designator (if any) to be that member.<sup><a href="#note131"><b>131)</b></a></sup> The current object that results at the end of the
designator list is the subobject to be initialized by the following initializer.
19 The initialization shall occur in initializer list order, each initializer provided for a
- particular subobject overriding any previously listed initializer for the same subobject;132)
+ particular subobject overriding any previously listed initializer for the same subobject;<sup><a href="#note132"><b>132)</b></a></sup>
all subobjects that are not initialized explicitly shall be initialized implicitly the same as
objects that have static storage duration.
20 If the aggregate or union contains elements or members that are aggregates or unions,
- 129) If the initializer list for a subaggregate or contained union does not begin with a left brace, its
+ <sup><a name="note129" href="#note129"><b>129)</b></a></sup> 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.
- 130) After a union member is initialized, the next object is not the next member of the union; instead, it is
+ <sup><a name="note130" href="#note130"><b>130)</b></a></sup> After a union member is initialized, the next object is not the next member of the union; instead, it is
the next subobject of an object containing the union.
- 131) Thus, a designator can only specify a strict subobject of the aggregate or union that is associated with
+ <sup><a name="note131" href="#note131"><b>131)</b></a></sup> Thus, a designator can only specify a strict subobject of the aggregate or union that is associated with
the surrounding brace pair. Note, too, that each separate designator list is independent.
- 132) Any initializer for the subobject which is overridden and so not used to initialize that subobject might
+ <sup><a name="note132" href="#note132"><b>132)</b></a></sup> Any initializer for the subobject which is overridden and so not used to initialize that subobject might
not be evaluated at all.
[<a name="p127" href="#p127">page 127</a>] (<a href="#Contents">Contents</a>)
23 The order in which any side effects occur among the initialization list expressions is
- unspecified.133)
+ unspecified.<sup><a href="#note133"><b>133)</b></a></sup>
24 EXAMPLE 1 Provided that <a href="#7.3"><complex.h></a> has been #included, the declarations
int i = <a href="#3.5">3.5</a>;
double complex c = 5 + 3 * I;
- 133) In particular, the evaluation order need not be the same as the order of subobject initialization.
+ <sup><a name="note133" href="#note133"><b>133)</b></a></sup> In particular, the evaluation order need not be the same as the order of subobject initialization.
[<a name="p128" href="#p128">page 128</a>] (<a href="#Contents">Contents</a>)
expressionopt ;
<b> Semantics</b>
2 The expression in an expression statement is evaluated as a void expression for its side
- effects.134)
+ effects.<sup><a href="#note134"><b>134)</b></a></sup>
3 A null statement (consisting of just a semicolon) performs no operations.
4 EXAMPLE 1 If a function call is evaluated as an expression statement for its side effects only, the
discarding of its value may be made explicit by converting the expression to a void expression by means of
- 134) Such as assignments, and function calls which have side effects.
+ <sup><a name="note134" href="#note134"><b>134)</b></a></sup> Such as assignments, and function calls which have side effects.
[<a name="p132" href="#p132">page 132</a>] (<a href="#Contents">Contents</a>)
1 The controlling expression of a switch statement shall have integer type.
2 If a switch statement has an associated case or default label within the scope of an
identifier with a variably modified type, the entire switch statement shall be within the
- scope of that identifier.135)
+ scope of that identifier.<sup><a href="#note135"><b>135)</b></a></sup>
3 The expression of each case label shall be an integer constant expression and no two of
the case constant expressions in the same switch statement shall have the same value
after conversion. There may be at most one default label in a switch statement.
- 135) That is, the declaration either precedes the switch statement, or it follows the last case or
+ <sup><a name="note135" href="#note135"><b>135)</b></a></sup> 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.
[<a name="p134" href="#p134">page 134</a>] (<a href="#Contents">Contents</a>)
<b> Semantics</b>
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
- whether the loop body is entered from the iteration statement or by a jump.136)
+ whether the loop body is entered from the iteration statement or by a jump.<sup><a href="#note136"><b>136)</b></a></sup>
5 An iteration statement is a block whose scope is a strict subset of the scope of its
enclosing block. The loop body is also a block whose scope is a strict subset of the scope
of the iteration statement.
- 136) Code jumped over is not executed. In particular, the controlling expression of a for or while
+ <sup><a name="note136" href="#note136"><b>136)</b></a></sup> 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.
[<a name="p135" href="#p135">page 135</a>] (<a href="#Contents">Contents</a>)
declaration, the scope of any identifiers it declares is the remainder of the declaration and
the entire loop, including the other two expressions; it is reached in the order of execution
before the first evaluation of the controlling expression. If clause-1 is an expression, it is
- evaluated as a void expression before the first evaluation of the controlling expression.137)
+ evaluated as a void expression before the first evaluation of the controlling expression.<sup><a href="#note137"><b>137)</b></a></sup>
2 Both clause-1 and expression-3 can be omitted. An omitted expression-2 is replaced by a
nonzero constant.
<a name="6.8.6" href="#6.8.6"><b> 6.8.6 Jump statements</b></a>
- 137) Thus, clause-1 specifies initialization for the loop, possibly declaring one or more variables for use in
+ <sup><a name="note137" href="#note137"><b>137)</b></a></sup> Thus, clause-1 specifies initialization for the loop, possibly declaring one or more variables for use in
the loop; the controlling expression, expression-2, specifies an evaluation made before each iteration,
such that execution of the loop continues until the expression compares equal to 0; and expression-3
specifies an operation (such as incrementing) that is performed after each iteration.
contin: ; contin: ; contin: ;
} } while (/* ... */); }
unless the continue statement shown is in an enclosed iteration statement (in which
- case it is interpreted within that statement), it is equivalent to goto contin;.138)
+ case it is interpreted within that statement), it is equivalent to goto contin;.<sup><a href="#note138"><b>138)</b></a></sup>
<a name="6.8.6.3" href="#6.8.6.3"><b> 6.8.6.3 The break statement</b></a>
<b> Constraints</b>
1 A break statement shall appear only in or as a switch body or loop body.
- 138) Following the contin: label is a null statement.
+ <sup><a name="note138" href="#note138"><b>138)</b></a></sup> Following the contin: label is a null statement.
[<a name="p138" href="#p138">page 138</a>] (<a href="#Contents">Contents</a>)
3 If a return statement with an expression is executed, the value of the expression is
returned to the caller as the value of the function call expression. If the expression has a
type different from the return type of the function in which it appears, the value is
- converted as if by assignment to an object having the return type of the function.139)
+ converted as if by assignment to an object having the return type of the function.<sup><a href="#note139"><b>139)</b></a></sup>
4 EXAMPLE In:
struct s { double i; } f(void);
union {
-
139) 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
+
<sup><a name="note139" href="#note139"><b>139)</b></a></sup> 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
range and precision.
linkage is used in an expression (other than as part of the operand of a sizeof operator
whose result is an integer constant), somewhere in the entire program there shall be
exactly one external definition for the identifier; otherwise, there shall be no more than
- one.140)
+ one.<sup><a href="#note140"><b>140)</b></a></sup>
- 140) Thus, if an identifier declared with external linkage is not used in an expression, there need be no
+ <sup><a name="note140" href="#note140"><b>140)</b></a></sup> Thus, if an identifier declared with external linkage is not used in an expression, there need be no
external definition for it.
[<a name="p140" href="#p140">page 140</a>] (<a href="#Contents">Contents</a>)
declaration-list declaration
<b> Constraints</b>
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.141)
+ have a function type, as specified by the declarator portion of the function definition.<sup><a href="#note141"><b>141)</b></a></sup>
3 The return type of a function shall be void or an object type other than array type.
4 The storage-class specifier, if any, in the declaration specifiers shall be either extern or
static.
- 141) The intent is that the type category in a function definition cannot be inherited from a typedef:
+ <sup><a name="note141" href="#note141"><b>141)</b></a></sup> The intent is that the type category in a function definition cannot be inherited from a typedef:
typedef int F(void); // type F is ''function with no parameters
// returning int''
F f, g; // f and g both have type compatible with F
and the identifiers of its parameters. If the declarator includes a parameter type list, the
list also specifies the types of all the parameters; such a declarator also serves as a
function prototype for later calls to the same function in the same translation unit. If the
- declarator includes an identifier list,142) the types of the parameters shall be declared in a
+ declarator includes an identifier list,<sup><a href="#note142"><b>142)</b></a></sup> the types of the parameters shall be declared in a
following declaration list. In either case, the type of each parameter is adjusted as
described in <a href="#6.7.5.3">6.7.5.3</a> for a parameter type list; the resulting type shall be an object type.
8 If a function that accepts a variable number of arguments is defined without a parameter
-
142) See ''future language directions'' (<a href="#6.11.7">6.11.7</a>).
+
<sup><a name="note142" href="#note142"><b>142)</b></a></sup> See ''future language directions'' (<a href="#6.11.7">6.11.7</a>).
[<a name="p142" href="#p142">page 142</a>] (<a href="#Contents">Contents</a>)
the start of translation phase 4) is either the first character in the source file (optionally
after white space containing no new-line characters) or that follows white space
containing at least one new-line character. The last token in the sequence is the first new-
- line character that follows the first token in the sequence.143) A new-line character ends
+ line character that follows the first token in the sequence.<sup><a href="#note143"><b>143)</b></a></sup> A new-line character ends
the preprocessing directive even if it occurs within what would otherwise be an
- 143) Thus, preprocessing directives are commonly called ''lines''. These ''lines'' have no other syntactic
+ <sup><a name="note143" href="#note143"><b>143)</b></a></sup> 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).
<b> Constraints</b>
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
- keywords) are interpreted as described below;144) and it may contain unary operator
+ keywords) are interpreted as described below;<sup><a href="#note144"><b>144)</b></a></sup> and it may contain unary operator
expressions of the form
- 144) Because the controlling constant expression is evaluated during translation phase 4, all identifiers
+ <sup><a name="note144" href="#note144"><b>144)</b></a></sup> 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.
[<a name="p147" href="#p147">page 147</a>] (<a href="#Contents">Contents</a>)
expression which is evaluated according to the rules of <a href="#6.6">6.6</a>. For the purposes of this
token conversion and evaluation, all signed integer types and all unsigned integer types
act as if they have the same representation as, respectively, the types intmax_t and
- uintmax_t defined in the header <a href="#7.18"><stdint.h></a>.145) This includes interpreting
+ uintmax_t defined in the header <a href="#7.18"><stdint.h></a>.<sup><a href="#note145"><b>145)</b></a></sup> This includes interpreting
character constants, which may involve converting escape sequences into execution
character set members. Whether the numeric value for these character constants matches
the value obtained when an identical character constant occurs in an expression (other
- than within a #if or #elif directive) is implementation-defined.146) Also, whether a
+ than within a #if or #elif directive) is implementation-defined.<sup><a href="#note146"><b>146)</b></a></sup> Also, whether a
single-character character constant may have a negative value is implementation-defined.
5 Preprocessing directives of the forms
- 145) Thus, on an implementation where INT_MAX is 0x7FFF and UINT_MAX is 0xFFFF, the constant
+ <sup><a name="note145" href="#note145"><b>145)</b></a></sup> Thus, on an implementation where INT_MAX is 0x7FFF and UINT_MAX is 0xFFFF, the constant
0x8000 is signed and positive within a #if expression even though it would be unsigned in
translation phase 7.
group. Only the first group whose control condition evaluates to true (nonzero) is
processed. If none of the conditions evaluates to true, and there is a #else directive, the
group controlled by the #else is processed; lacking a #else directive, all the groups
- until the #endif are skipped.147)
+ until the #endif are skipped.<sup><a href="#note147"><b>147)</b></a></sup>
Forward references: 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>).
<a name="6.10.2" href="#6.10.2"><b> 6.10.2 Source file inclusion</b></a>
- 146) Thus, the constant expression in the following #if directive and if statement is not guaranteed to
+ <sup><a name="note146" href="#note146"><b>146)</b></a></sup> Thus, the constant expression in the following #if directive and if statement is not guaranteed to
evaluate to the same value in these two contexts.
#if 'z' - 'a' == 25
if ('z' - 'a' == 25)
- 147) As indicated by the syntax, a preprocessing token shall not follow a #else or #endif directive
+ <sup><a name="note147" href="#note147"><b>147)</b></a></sup> As indicated by the syntax, a preprocessing token shall not follow a #else or #endif directive
before the terminating new-line character. However, comments may appear anywhere in a source file,
including within a preprocessing directive.
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
preprocessing tokens.) The directive resulting after all replacements shall match one of
- the two previous forms.148) The method by which a sequence of preprocessing tokens
+ the two previous forms.<sup><a href="#note148"><b>148)</b></a></sup> The method by which a sequence of preprocessing tokens
between a < and a > preprocessing token pair or a pair of " characters is combined into a
single header name preprocessing token is implementation-defined.
5 The implementation shall provide unique mappings for sequences consisting of one or
- 148) Note that adjacent string literals are not concatenated into a single string literal (see the translation
+ <sup><a name="note148" href="#note148"><b>148)</b></a></sup> 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.
[<a name="p150" href="#p150">page 150</a>] (<a href="#Contents">Contents</a>)
a preprocessing directive could begin, the identifier is not subject to macro replacement.
9 A preprocessing directive of the form
# define identifier replacement-list new-line
- defines an object-like macro that causes each subsequent instance of the macro name149)
+ 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
as specified below.
the list are separated by comma preprocessing tokens, but comma preprocessing tokens
between matching inner parentheses do not separate arguments. If there are sequences of
preprocessing tokens within the list of arguments that would otherwise act as
- preprocessing directives,150) the behavior is undefined.
+ preprocessing directives,<sup><a href="#note150"><b>150)</b></a></sup> the behavior is undefined.
12 If there is a ... in the identifier-list in the macro definition, then the trailing arguments,
including any separating comma preprocessing tokens, are merged to form a single item:
the variable arguments. The number of arguments so combined is such that, following
- 149) Since, by macro-replacement time, all character constants and string literals are preprocessing tokens,
+ <sup><a name="note149" href="#note149"><b>149)</b></a></sup> 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.
- 150) Despite the name, a non-directive is a preprocessing directive.
+ <sup><a name="note150" href="#note150"><b>150)</b></a></sup> Despite the name, a non-directive is a preprocessing directive.
[<a name="p152" href="#p152">page 152</a>] (<a href="#Contents">Contents</a>)
or followed by a ## preprocessing token, the parameter is replaced by the corresponding
argument's preprocessing token sequence; however, if an argument consists of no
preprocessing tokens, the parameter is replaced by a placemarker preprocessing token
- instead.151)
+ instead.<sup><a href="#note151"><b>151)</b></a></sup>
3 For both object-like and function-like macro invocations, before the replacement list is
reexamined for more macro names to replace, each instance of a ## preprocessing token
in the replacement list (not from an argument) is deleted and the preceding preprocessing
this new token is not the ## operator.
- 151) Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
+ <sup><a name="note151" href="#note151"><b>151)</b></a></sup> Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
exist only within translation phase 4.
[<a name="p154" href="#p154">page 154</a>] (<a href="#Contents">Contents</a>)
1 A preprocessing directive of the form
# pragma pp-tokensopt new-line
where the preprocessing token STDC does not immediately follow pragma in the
- directive (prior to any macro replacement)152) causes the implementation to behave in an
+ 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
translator or the resulting program to behave in a non-conforming manner. Any such
pragma that is not recognized by the implementation is ignored.
2 If the preprocessing token STDC does immediately follow pragma in the directive (prior
to any macro replacement), then no macro replacement is performed on the directive, and
- the directive shall have one of the following forms153) whose meanings are described
+ the directive shall have one of the following forms<sup><a href="#note153"><b>153)</b></a></sup> whose meanings are described
elsewhere:
#pragma STDC FP_CONTRACT on-off-switch
#pragma STDC FENV_ACCESS on-off-switch
- 152) An implementation is not required to perform macro replacement in pragmas, but it is permitted
+ <sup><a name="note152" href="#note152"><b>152)</b></a></sup> 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
implementation-defined; an implementation is permitted to behave as if it were the standard pragma,
but is not required to.
-
153) See ''future language directions'' (<a href="#6.11.8">6.11.8</a>).
+
<sup><a name="note153" href="#note153"><b>153)</b></a></sup> See ''future language directions'' (<a href="#6.11.8">6.11.8</a>).
[<a name="p159" href="#p159">page 159</a>] (<a href="#Contents">Contents</a>)
# new-line
has no effect.
<a name="6.10.8" href="#6.10.8"><b> 6.10.8 Predefined macro names</b></a>
-1 The following macro names154) shall be defined by the implementation:
+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
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.
- __FILE__ The presumed name of the current source file (a character string literal).155)
+ __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
source line (an integer constant).155)
__STDC__ The integer constant 1, intended to indicate a conforming implementation.
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.
- __STDC_VERSION__ The integer constant 199901L.156)
+ __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
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
-
154) See ''future language directions'' (<a href="#6.11.9">6.11.9</a>).
- 155) The presumed source file name and line number can be changed by the #line directive.
- 156) This macro was not specified in ISO/IEC 9899:1990 and was specified as 199409L in
+
<sup><a name="note154" href="#note154"><b>154)</b></a></sup> See ''future language directions'' (<a href="#6.11.9">6.11.9</a>).
+ <sup><a name="note155" href="#note155"><b>155)</b></a></sup> The presumed source file name and line number can be changed by the #line directive.
+ <sup><a name="note156" href="#note156"><b>156)</b></a></sup> This macro was not specified in ISO/IEC 9899:1990 and was specified as 199409L in
ISO/IEC 9899/AMD1:1995. The intention is that this will remain an integer constant of type long
int that is increased with each revision of this International Standard.
the value of a string is the sequence of the values of the contained characters, in order.
2 The decimal-point character is the character used by functions that convert floating-point
numbers to or from character sequences to denote the beginning of the fractional part of
- such character sequences.157) It is represented in the text and examples by a period, but
+ such character sequences.<sup><a href="#note157"><b>157)</b></a></sup> It is represented in the text and examples by a period, but
may be changed by the setlocale function.
3 A null wide character is a wide character with code value zero.
4 A wide string is a contiguous sequence of wide characters terminated by and including
5 A shift sequence is a contiguous sequence of bytes within a multibyte string that
(potentially) causes a change in shift state (see <a href="#5.2.1.2">5.2.1.2</a>). A shift sequence shall not have a
corresponding wide character; it is instead taken to be an adjunct to an adjacent multibyte
- character.158)
+ character.<sup><a href="#note158"><b>158)</b></a></sup>
Forward references: character handling (<a href="#7.4">7.4</a>), the setlocale function (<a href="#7.11.1.1">7.11.1.1</a>).
- 157) The functions that make use of the decimal-point character are the numeric conversion functions
+ <sup><a name="note157" href="#note157"><b>157)</b></a></sup> 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>).
- 158) For state-dependent encodings, the values for MB_CUR_MAX and MB_LEN_MAX shall thus be large
+ <sup><a name="note158" href="#note158"><b>158)</b></a></sup> For state-dependent encodings, the values for MB_CUR_MAX and MB_LEN_MAX shall thus be large
enough to count all the bytes in any complete multibyte character plus at least one adjacent shift
sequence of maximum length. Whether these counts provide for more than one shift sequence is the
implementation's choice.
[<a name="p164" href="#p164">page 164</a>] (<a href="#Contents">Contents</a>)
<a name="7.1.2" href="#7.1.2"><b> 7.1.2 Standard headers</b></a>
-1 Each library function is declared, with a type that includes a prototype, in a header,159)
+1 Each library function is declared, with a type that includes a prototype, in a header,<sup><a href="#note159"><b>159)</b></a></sup>
whose contents are made available by the #include preprocessing directive. The
header declares a set of related functions, plus any necessary types and additional macros
needed to facilitate their use. Declarations of types described in this clause shall not
- 159) A header is not necessarily a source file, nor are the < and > delimited sequences in header names
+ <sup><a name="note159" href="#note159"><b>159)</b></a></sup> A header is not necessarily a source file, nor are the < and > delimited sequences in header names
necessarily valid source file names.
[<a name="p165" href="#p165">page 165</a>] (<a href="#Contents">Contents</a>)
unless explicitly stated otherwise (see <a href="#7.1.4">7.1.4</a>).
-- All identifiers with external linkage in any of the following subclauses (including the
future library directions) are always reserved for use as identifiers with external
- linkage.160)
+ linkage.<sup><a href="#note160"><b>160)</b></a></sup>
-- Each identifier with file scope listed in any of the following subclauses (including the
future library directions) is reserved for use as a macro name and as an identifier with
file scope in the same name space if any of its associated headers is included.
pointer did point to the first element of such an array) are in fact valid. Any function
declared in a header may be additionally implemented as a function-like macro defined in
- 160) The list of reserved identifiers with external linkage includes errno, math_errhandling,
+ <sup><a name="note160" href="#note160"><b>160)</b></a></sup> The list of reserved identifiers with external linkage includes errno, math_errhandling,
setjmp, and va_end.
[<a name="p166" href="#p166">page 166</a>] (<a href="#Contents">Contents</a>)
the name of the function in parentheses, because the name is then not followed by the left
parenthesis that indicates expansion of a macro function name. For the same syntactic
reason, it is permitted to take the address of a library function even if it is also defined as
- a macro.161) The use of #undef to remove any macro definition will also ensure that an
+ a macro.<sup><a href="#note161"><b>161)</b></a></sup> The use of #undef to remove any macro definition will also ensure that an
actual function is referred to. Any invocation of a library function that is implemented as
a macro shall expand to code that evaluates each of its arguments exactly once, fully
protected by parentheses where necessary, so it is generally safe to use arbitrary
- expressions as arguments.162) Likewise, those function-like macros described in the
+ expressions as arguments.<sup><a href="#note162"><b>162)</b></a></sup> Likewise, those function-like macros described in the
following subclauses may be invoked in an expression anywhere a function with a
- compatible return type could be called.163) All object-like macros listed as expanding to
+ compatible return type could be called.<sup><a href="#note163"><b>163)</b></a></sup> All object-like macros listed as expanding to
integer constant expressions shall additionally be suitable for use in #if preprocessing
directives.
2 Provided that a library function can be declared without reference to any type defined in a
associated header.
3 There is a sequence point immediately before a library function returns.
4 The functions in the standard library are not guaranteed to be reentrant and may modify
- objects with static storage duration.164)
+ objects with static storage duration.<sup><a href="#note164"><b>164)</b></a></sup>
- 161) This means that an implementation shall provide an actual function for each library function, even if it
+ <sup><a name="note161" href="#note161"><b>161)</b></a></sup> This means that an implementation shall provide an actual function for each library function, even if it
also provides a macro for that function.
- 162) Such macros might not contain the sequence points that the corresponding function calls do.
- 163) Because external identifiers and some macro names beginning with an underscore are reserved,
+ <sup><a name="note162" href="#note162"><b>162)</b></a></sup> Such macros might not contain the sequence points that the corresponding function calls do.
+ <sup><a name="note163" href="#note163"><b>163)</b></a></sup> Because external identifiers and some macro names beginning with an underscore are reserved,
implementations may provide special semantics for such names. For example, the identifier
_BUILTIN_abs could be used to indicate generation of in-line code for the abs function. Thus, the
appropriate header could specify
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.
- 164) Thus, a signal handler cannot, in general, call standard library functions.
+ <sup><a name="note164" href="#note164"><b>164)</b></a></sup> Thus, a signal handler cannot, in general, call standard library functions.
[<a name="p167" href="#p167">page 167</a>] (<a href="#Contents">Contents</a>)
failed (including the text of the argument, the name of the source file, the source line
number, and the name of the enclosing function -- the latter are respectively the values of
the preprocessing macros __FILE__ and __LINE__ and of the identifier
- __func__) on the standard error stream in an implementation-defined format.165) It
+ __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.
<b> Returns</b>
3 The assert macro returns no value.
- 165) The message written might be of the form:
+ <sup><a name="note165" href="#note165"><b>165)</b></a></sup> The message written might be of the form:
Assertion failed: expression, function abc, file xyz, line nnn.
<a name="7.3" href="#7.3"><b> 7.3 Complex arithmetic <complex.h></b></a>
<a name="7.3.1" href="#7.3.1"><b> 7.3.1 Introduction</b></a>
1 The header <a href="#7.3"><complex.h></a> defines macros and declares functions that support complex
- arithmetic.166) Each synopsis specifies a family of functions consisting of a principal
+ arithmetic.<sup><a href="#note166"><b>166)</b></a></sup> Each synopsis specifies a family of functions consisting of a principal
function with one or more double complex parameters and a double complex or
double return value; and other functions with the same name but with f and l suffixes
which are corresponding functions with float and long double parameters and
expands to _Complex; the macro
_Complex_I
expands to a constant expression of type const float _Complex, with the value of
- the imaginary unit.167)
+ the imaginary unit.<sup><a href="#note167"><b>167)</b></a></sup>
3 The macros
imaginary
and
_Imaginary_I
- are defined if and only if the implementation supports imaginary types;168) if defined,
+ 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.
4 The macro
-
166) See ''future library directions'' (<a href="#7.26.1">7.26.1</a>).
- 167) The imaginary unit is a number i such that i 2 = -1.
-
168) A specification for imaginary types is in informative <a href="#G">annex G</a>.
+
<sup><a name="note166" href="#note166"><b>166)</b></a></sup> See ''future library directions'' (<a href="#7.26.1">7.26.1</a>).
+ <sup><a name="note167" href="#note167"><b>167)</b></a></sup> The imaginary unit is a number i such that i 2 = -1.
+
<sup><a name="note168" href="#note168"><b>168)</b></a></sup> A specification for imaginary types is in informative <a href="#G">annex G</a>.
[<a name="p170" href="#p170">page 170</a>] (<a href="#Contents">Contents</a>)
problematic because of their treatment of infinities and because of undue overflow and
underflow. The CX_LIMITED_RANGE pragma can be used to inform the
implementation that (where the state is ''on'') the usual mathematical formulas are
- acceptable.169) The pragma can occur either outside external declarations or preceding all
+ acceptable.<sup><a href="#note169"><b>169)</b></a></sup> The pragma can occur either outside external declarations or preceding all
explicit declarations and statements inside a compound statement. When outside external
- 169) The purpose of the pragma is to allow the implementation to use the formulas:
+ <sup><a name="note169" href="#note169"><b>169)</b></a></sup> The purpose of the pragma is to allow the implementation to use the formulas:
(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
[<a name="p178" href="#p178">page 178</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
-2 The cimag functions compute the imaginary part of z.170)
+2 The cimag functions compute the imaginary part of z.<sup><a href="#note170"><b>170)</b></a></sup>
<b> Returns</b>
3 The cimag functions return the imaginary part value (as a real).
<a name="7.3.9.3" href="#7.3.9.3"><b> 7.3.9.3 The conj functions</b></a>
- 170) For a variable z of complex type, z == creal(z) + cimag(z)*I.
+ <sup><a name="note170" href="#note170"><b>170)</b></a></sup> For a variable z of complex type, z == creal(z) + cimag(z)*I.
[<a name="p179" href="#p179">page 179</a>] (<a href="#Contents">Contents</a>)
float crealf(float complex z);
long double creall(long double complex z);
<b> Description</b>
-2 The creal functions compute the real part of z.171)
+2 The creal functions compute the real part of z.<sup><a href="#note171"><b>171)</b></a></sup>
<b> Returns</b>
3 The creal functions return the real part value.
- 171) For a variable z of complex type, z == creal(z) + cimag(z)*I.
+ <sup><a name="note171" href="#note171"><b>171)</b></a></sup> For a variable z of complex type, z == creal(z) + cimag(z)*I.
[<a name="p180" href="#p180">page 180</a>] (<a href="#Contents">Contents</a>)
<a name="7.4" href="#7.4"><b> 7.4 Character handling <ctype.h></b></a>
1 The header <a href="#7.4"><ctype.h></a> declares several functions useful for classifying and mapping
- characters.172) In all cases the argument is an int, the value of which shall be
+ characters.<sup><a href="#note172"><b>172)</b></a></sup> In all cases the argument is an int, the value of which shall be
representable as an unsigned char or shall equal the value of the macro EOF. If the
argument has any other value, the behavior is undefined.
2 The behavior of these functions is affected by the current locale. Those functions that
3 The term printing character refers to a member of a locale-specific set of characters, each
of which occupies one printing position on a display device; the term control character
refers to a member of a locale-specific set of characters that are not printing
- characters.173) All letters and digits are printing characters.
+ characters.<sup><a href="#note173"><b>173)</b></a></sup> All letters and digits are printing characters.
Forward references: EOF (<a href="#7.19.1">7.19.1</a>), localization (<a href="#7.11">7.11</a>).
<a name="7.4.1" href="#7.4.1"><b> 7.4.1 Character classification functions</b></a>
1 The functions in this subclause return nonzero (true) if and only if the value of the
-
172) See ''future library directions'' (<a href="#7.26.2">7.26.2</a>).
- 173) In an implementation that uses the seven-bit US ASCII character set, the printing characters are those
+
<sup><a name="note172" href="#note172"><b>172)</b></a></sup> See ''future library directions'' (<a href="#7.26.2">7.26.2</a>).
+ <sup><a name="note173" href="#note173"><b>173)</b></a></sup> In an implementation that uses the seven-bit US ASCII character set, the printing characters are those
whose values lie from 0x20 (space) through 0x7E (tilde); the control characters are those whose
values lie from 0 (NUL) through 0x1F (US), and the character 0x7F (DEL).
[<a name="p181" href="#p181">page 181</a>] (<a href="#Contents">Contents</a>)
- none of iscntrl, isdigit, ispunct, or isspace is true.174) In the "C" locale,
+ 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.
<a name="7.4.1.3" href="#7.4.1.3"><b> 7.4.1.3 The isblank function</b></a>
<b> Synopsis</b>
- 174) The functions islower and isupper test true or false separately for each of these additional
+ <sup><a name="note174" href="#note174"><b>174)</b></a></sup> The functions islower and isupper test true or false separately for each of these additional
characters; all four combinations are possible.
[<a name="p182" href="#p182">page 182</a>] (<a href="#Contents">Contents</a>)
which expand to integer constant expressions with type int, distinct positive values, and
which are suitable for use in #if preprocessing directives; and
errno
- which expands to a modifiable lvalue175) that has type int, the value of which is set to a
+ 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
in order to access an actual object, or a program defines an identifier with the name
errno, the behavior is undefined.
3 The value of errno is zero at program startup, but is never set to zero by any library
- function.176) The value of errno may be set to nonzero by a library function call
+ function.<sup><a href="#note176"><b>176)</b></a></sup> The value of errno may be set to nonzero by a library function call
whether or not there is an error, provided the use of errno is not documented in the
description of the function in this International Standard.
4 Additional macro definitions, beginning with E and a digit or E and an uppercase
- letter,177) may also be specified by the implementation.
+ letter,<sup><a href="#note177"><b>177)</b></a></sup> may also be specified by the implementation.
- 175) The macro errno need not be the identifier of an object. It might expand to a modifiable lvalue
+ <sup><a name="note175" href="#note175"><b>175)</b></a></sup> 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()).
- 176) Thus, a program that uses errno for error checking should set it to zero before a library function call,
+ <sup><a name="note176" href="#note176"><b>176)</b></a></sup> Thus, a program that uses errno for error checking should set it to zero before a library function call,
then inspect it before a subsequent library function call. Of course, a library function can save the
value of errno on entry and then set it to zero, as long as the original value is restored if errno's
value is still zero just before the return.
-
177) See ''future library directions'' (<a href="#7.26.3">7.26.3</a>).
+
<sup><a name="note177" href="#note177"><b>177)</b></a></sup> See ''future library directions'' (<a href="#7.26.3">7.26.3</a>).
[<a name="p186" href="#p186">page 186</a>] (<a href="#Contents">Contents</a>)
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
collectively to any floating-point status flags and control modes supported by the
- implementation.178) A floating-point status flag is a system variable whose value is set
+ implementation.<sup><a href="#note178"><b>178)</b></a></sup> A floating-point status flag is a system variable whose value is set
(but never cleared) when a floating-point exception is raised, which occurs as a side effect
- of exceptional floating-point arithmetic to provide auxiliary information.179) A floating-
+ of exceptional floating-point arithmetic to provide auxiliary information.<sup><a href="#note179"><b>179)</b></a></sup> A floating-
point control mode is a system variable whose value may be set by the user to affect the
subsequent behavior of floating-point arithmetic.
2 Certain programming conventions support the intended model of use for the floating-
- point environment:180)
+ point environment:<sup><a href="#note180"><b>180)</b></a></sup>
-- a function call does not alter its caller's floating-point control modes, clear its caller's
floating-point status flags, nor depend on the state of its caller's floating-point status
flags unless the function is so documented;
- 178) This header is designed to support the floating-point exception status flags and directed-rounding
+ <sup><a name="note178" href="#note178"><b>178)</b></a></sup> 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.
- 179) A floating-point status flag is not an object and can be set more than once within an expression.
- 180) With these conventions, a programmer can safely assume default floating-point control modes (or be
+ <sup><a name="note179" href="#note179"><b>179)</b></a></sup> A floating-point status flag is not an object and can be set more than once within an expression.
+ <sup><a name="note180" href="#note180"><b>180)</b></a></sup> With these conventions, a programmer can safely assume default floating-point control modes (or be
unaware of them). The responsibilities associated with accessing the floating-point environment fall
on the programmer or program that does so explicitly.
FE_OVERFLOW
FE_UNDERFLOW
is defined if and only if the implementation supports the floating-point exception by
- means of the functions in 7.6.2.181) Additional implementation-defined floating-point
+ 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
be specified by the implementation. The defined macros expand to integer constant
expressions with values such that bitwise ORs of all combinations of the macros result in
distinct values, and furthermore, bitwise ANDs of all combinations of the macros result in
- zero.182)
+ zero.<sup><a href="#note182"><b>182)</b></a></sup>
6 The macro
FE_ALL_EXCEPT
is simply the bitwise OR of all floating-point exception macros defined by the
Additional implementation-defined rounding directions, with macro definitions beginning
with FE_ and an uppercase letter, may also be specified by the implementation. The
defined macros expand to integer constant expressions whose values are distinct
- nonnegative values.183)
+ nonnegative values.<sup><a href="#note183"><b>183)</b></a></sup>
8 The macro
- 181) The implementation supports an exception if there are circumstances where a call to at least one of the
+ <sup><a name="note181" href="#note181"><b>181)</b></a></sup> The implementation supports an exception if there are circumstances where a call to at least one of the
functions in <a href="#7.6.2">7.6.2</a>, using the macro as the appropriate argument, will succeed. It is not necessary for
all the functions to succeed all the time.
- 182) The macros should be distinct powers of two.
- 183) Even though the rounding direction macros may expand to constants corresponding to the values of
+ <sup><a name="note182" href="#note182"><b>182)</b></a></sup> The macros should be distinct powers of two.
+ <sup><a name="note183" href="#note183"><b>183)</b></a></sup> Even though the rounding direction macros may expand to constants corresponding to the values of
FLT_ROUNDS, they are not required to do so.
[<a name="p188" href="#p188">page 188</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
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
- run under non-default floating-point control modes.184) The pragma shall occur either
+ run under non-default floating-point control modes.<sup><a href="#note184"><b>184)</b></a></sup> The pragma shall occur either
outside external declarations or preceding all explicit declarations and statements inside a
compound statement. When outside external declarations, the pragma takes effect from
its occurrence until another FENV_ACCESS pragma is encountered, or until the end of
- 184) The purpose of the FENV_ACCESS pragma is to allow certain optimizations that could subvert flag
+ <sup><a name="note184" href="#note184"><b>184)</b></a></sup> 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
modes are in effect and the flags are not tested.
}
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.185)
+ contain an appropriately placed invocation of #pragma STDC FENV_ACCESS ON.<sup><a href="#note185"><b>185)</b></a></sup>
<a name="7.6.2" href="#7.6.2"><b> 7.6.2 Floating-point exceptions</b></a>
-1 The following functions provide access to the floating-point status flags.186) The int
+1 The following functions provide access to the floating-point status flags.<sup><a href="#note186"><b>186)</b></a></sup> The int
input argument for the functions represents a subset of floating-point exceptions, and can
be zero or the bitwise OR of one or more floating-point exception macros, for example
FE_OVERFLOW | FE_INEXACT. For other argument values the behavior of these
the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value.
- 185) The side effects impose a temporal ordering that requires two evaluations of x + 1. On the other
+ <sup><a name="note185" href="#note185"><b>185)</b></a></sup> The side effects impose a temporal ordering that requires two evaluations of x + 1. On the other
hand, without the #pragma STDC FENV_ACCESS ON pragma, and assuming the default state is
''off'', just one evaluation of x + 1 would suffice.
- 186) The functions fetestexcept, feraiseexcept, and feclearexcept support the basic
+ <sup><a name="note186" href="#note186"><b>186)</b></a></sup> 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-
point exception; the functions fegetexceptflag and fesetexceptflag deal with the full
int feraiseexcept(int excepts);
<b> Description</b>
2 The feraiseexcept function attempts to raise the supported floating-point exceptions
- represented by its argument.187) The order in which these floating-point exceptions are
+ 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.
- 187) The effect is intended to be similar to that of floating-point exceptions raised by arithmetic operations.
+ <sup><a name="note187" href="#note187"><b>187)</b></a></sup> 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.
<b> Description</b>
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.188)
+ point status flags to be queried.<sup><a href="#note188"><b>188)</b></a></sup>
<b> Returns</b>
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
- 188) This mechanism allows testing several floating-point exceptions with just one function call.
+ <sup><a name="note188" href="#note188"><b>188)</b></a></sup> This mechanism allows testing several floating-point exceptions with just one function call.
[<a name="p192" href="#p192">page 192</a>] (<a href="#Contents">Contents</a>)
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.189)
+ exceptions.<sup><a href="#note189"><b>189)</b></a></sup>
[<a name="p194" href="#p194">page 194</a>] (<a href="#Contents">Contents</a>)
- 189) IEC 60559 systems have a default non-stop mode, and typically at least one other mode for trap
+ <sup><a name="note189" href="#note189"><b>189)</b></a></sup> IEC 60559 systems have a default non-stop mode, and typically at least one other mode for trap
handling or aborting; if the system provides only the non-stop mode then installing it is trivial. For
such systems, the feholdexcept function can be used in conjunction with the feupdateenv
function to write routines that hide spurious floating-point exceptions from their callers.
imaxdiv_t
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.190)
+ specifiers for use with the formatted input/output functions.<sup><a href="#note190"><b>190)</b></a></sup>
Forward references: 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>).
<a name="7.8.1" href="#7.8.1"><b> 7.8.1 Macros for format specifiers</b></a>
-1 Each of the following object-like macros191) expands to a character string literal
+1 Each of the following object-like macros<sup><a href="#note191"><b>191)</b></a></sup> expands to a character string literal
containing a conversion specifier, possibly modified by a length modifier, suitable for use
within the format argument of a formatted input/output function when converting the
corresponding integer type. These macro names have the general form of PRI (character
string literals for the fprintf and fwprintf family) or SCN (character string literals
- for the fscanf and fwscanf family),192) followed by the conversion specifier,
+ for the fscanf and fwscanf family),<sup><a href="#note192"><b>192)</b></a></sup> followed by the conversion specifier,
followed by a name corresponding to a similar type name in <a href="#7.18.1">7.18.1</a>. In these names, N
represents the width of the type as described in <a href="#7.18.1">7.18.1</a>. For example, PRIdFAST32 can
be used in a format string to print the value of an integer of type int_fast32_t.
-
190) See ''future library directions'' (<a href="#7.26.4">7.26.4</a>).
- 191) C++ implementations should define these macros only when __STDC_FORMAT_MACROS is defined
+
<sup><a name="note190" href="#note190"><b>190)</b></a></sup> See ''future library directions'' (<a href="#7.26.4">7.26.4</a>).
+ <sup><a name="note191" href="#note191"><b>191)</b></a></sup> C++ implementations should define these macros only when __STDC_FORMAT_MACROS is defined
before <a href="#7.8"><inttypes.h></a> is included.
- 192) Separate macros are given for use with fprintf and fscanf functions because, in the general case,
+ <sup><a name="note192" href="#note192"><b>192)</b></a></sup> Separate macros are given for use with fprintf and fscanf functions because, in the general case,
different format specifiers may be required for fprintf and fscanf, even when the type is the
same.
intmax_t imaxabs(intmax_t j);
<b> Description</b>
2 The imaxabs function computes the absolute value of an integer j. If the result cannot
- be represented, the behavior is undefined.193)
+ be represented, the behavior is undefined.<sup><a href="#note193"><b>193)</b></a></sup>
- 193) The absolute value of the most negative number cannot be represented in two's complement.
+ <sup><a name="note193" href="#note193"><b>193)</b></a></sup> The absolute value of the most negative number cannot be represented in two's complement.
[<a name="p199" href="#p199">page 199</a>] (<a href="#Contents">Contents</a>)
LC_NUMERIC
LC_TIME
which expand to integer constant expressions with distinct values, suitable for use as the
- first argument to the setlocale function.194) Additional macro definitions, beginning
- with the characters LC_ and an uppercase letter,195) may also be specified by the
+ 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.
<a name="7.11.1" href="#7.11.1"><b> 7.11.1 Locale control</b></a>
<a name="7.11.1.1" href="#7.11.1.1"><b> 7.11.1.1 The setlocale function</b></a>
LC_ALL for category names the program's entire locale; the other values for
category name only a portion of the program's locale. LC_COLLATE affects the
behavior of the strcoll and strxfrm functions. LC_CTYPE affects the behavior of
- the character handling functions196) and the multibyte and wide character functions.
+ the character handling functions<sup><a href="#note196"><b>196)</b></a></sup> and the multibyte and wide character functions.
LC_MONETARY affects the monetary formatting information returned by the
localeconv function. LC_NUMERIC affects the decimal-point character for the
formatted input/output functions and the string conversion functions, as well as the
of "" for locale specifies the locale-specific native environment. Other
implementation-defined strings may be passed as the second argument to setlocale.
- 194) ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C.
-
195) See ''future library directions'' (<a href="#7.26.5">7.26.5</a>).
-
196) The only functions in <a href="#7.4">7.4</a> whose behavior is not affected by the current locale are isdigit and
+ <sup><a name="note194" href="#note194"><b>194)</b></a></sup> ISO/IEC 9945-2 specifies locale and charmap formats that may be used to specify locales for C.
+
<sup><a name="note195" href="#note195"><b>195)</b></a></sup> See ''future library directions'' (<a href="#7.26.5">7.26.5</a>).
+
<sup><a name="note196" href="#note196"><b>196)</b></a></sup> The only functions in <a href="#7.4">7.4</a> whose behavior is not affected by the current locale are isdigit and
isxdigit.
[<a name="p205" href="#p205">page 205</a>] (<a href="#Contents">Contents</a>)
function returns a null pointer and the program's locale is not changed.
7 A null pointer for locale causes the setlocale function to return a pointer to the
string associated with the category for the program's current locale; the program's
- locale is not changed.197)
+ locale is not changed.<sup><a href="#note197"><b>197)</b></a></sup>
8 The pointer to string returned by the setlocale function is such that a subsequent call
with that string value and its associated category will restore that part of the program's
locale. The string pointed to shall not be modified by the program, but may be
(except decimal_point) can point to "", to indicate that the value is not available in
the current locale or is of zero length. Apart from grouping and mon_grouping, the
- 197) The implementation shall arrange to encode in a string the various categories due to a heterogeneous
+ <sup><a name="note197" href="#note197"><b>197)</b></a></sup> The implementation shall arrange to encode in a string the various categories due to a heterogeneous
locale when category has the value LC_ALL.
[<a name="p206" href="#p206">page 206</a>] (<a href="#Contents">Contents</a>)
several macros. Most synopses specify a family of functions consisting of a principal
function with one or more double parameters, a double return value, or both; and
other functions with the same name but with f and l suffixes, which are corresponding
- functions with float and long double parameters, return values, or both.198)
+ functions with float and long double parameters, return values, or both.<sup><a href="#note198"><b>198)</b></a></sup>
Integer arithmetic functions and conversion functions are discussed later.
2 The types
float_t
float_t and double_t are float and double, respectively; if
FLT_EVAL_METHOD equals 1, they are both double; if FLT_EVAL_METHOD equals
2, they are both long double; and for other values of FLT_EVAL_METHOD, they are
- otherwise implementation-defined.199)
+ otherwise implementation-defined.<sup><a href="#note199"><b>199)</b></a></sup>
3 The macro
HUGE_VAL
expands to a positive double constant expression, not necessarily representable as a
float. The macros
HUGE_VALF
HUGE_VALL
- are respectively float and long double analogs of HUGE_VAL.200)
+ are respectively float and long double analogs of HUGE_VAL.<sup><a href="#note200"><b>200)</b></a></sup>
4 The macro
INFINITY
expands to a constant expression of type float representing positive or unsigned
-
198) Particularly on systems with wide expression evaluation, a <a href="#7.12"><math.h></a> function might pass arguments
+
<sup><a name="note198" href="#note198"><b>198)</b></a></sup> 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.
- 199) The types float_t and double_t are intended to be the implementation's most efficient types at
+ <sup><a name="note199" href="#note199"><b>199)</b></a></sup> The types float_t and double_t are intended to be the implementation's most efficient types at
least as wide as float and double, respectively. For FLT_EVAL_METHOD equal 0, 1, or 2, the
type float_t is the narrowest type used by the implementation to evaluate floating expressions.
- 200) HUGE_VAL, HUGE_VALF, and HUGE_VALL can be positive infinities in an implementation that
+ <sup><a name="note200" href="#note200"><b>200)</b></a></sup> HUGE_VAL, HUGE_VALF, and HUGE_VALL can be positive infinities in an implementation that
supports infinities.
[<a name="p212" href="#p212">page 212</a>] (<a href="#Contents">Contents</a>)
- translation time.201)
+ translation time.<sup><a href="#note201"><b>201)</b></a></sup>
5 The macro
NAN
is defined if and only if the implementation supports quiet NaNs for the float type. It
7 The macro
FP_FAST_FMA
is optionally defined. If defined, it indicates that the fma function generally executes
- about as fast as, or faster than, a multiply and an add of double operands.202) The
+ 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
FP_FAST_FMAF
FP_FAST_FMAL
-INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN.
-
201) In this case, using INFINITY will violate the constraint in <a href="#6.4.4">6.4.4</a> and thus require a diagnostic.
- 202) Typically, the FP_FAST_FMA macro is defined if and only if the fma function is implemented
+
<sup><a name="note201" href="#note201"><b>201)</b></a></sup> In this case, using INFINITY will violate the constraint in <a href="#6.4.4">6.4.4</a> and thus require a diagnostic.
+ <sup><a name="note202" href="#note202"><b>202)</b></a></sup> Typically, the FP_FAST_FMA macro is defined if and only if the fma function is implemented
directly with a hardware multiply-add instruction. Software implementations are expected to be
substantially slower.
2 For all functions, a domain error occurs if an input argument is outside the domain over
which the mathematical function is defined. The description of each function lists any
required domain errors; an implementation may define additional domain errors, provided
- that such errors are consistent with the mathematical definition of the function.203) On a
+ that such errors are consistent with the mathematical definition of the function.<sup><a href="#note203"><b>203)</b></a></sup> On a
domain error, the function returns an implementation-defined value; if the integer
expression math_errhandling & MATH_ERRNO is nonzero, the integer expression
errno acquires the value EDOM; if the integer expression math_errhandling &
example log(0.0)), then the function returns the value of the macro HUGE_VAL,
- 203) In an implementation that supports infinities, this allows an infinity as an argument to be a domain
+ <sup><a name="note203" href="#note203"><b>203)</b></a></sup> 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.
[<a name="p214" href="#p214">page 214</a>] (<a href="#Contents">Contents</a>)
infinity and the ''overflow'' floating-point exception is raised otherwise.
5 The result underflows if the magnitude of the mathematical result is so small that the
mathematical result cannot be represented, without extraordinary roundoff error, in an
- object of the specified type.204) If the result underflows, the function returns an
+ object of the specified type.<sup><a href="#note204"><b>204)</b></a></sup> If the result underflows, the function returns an
implementation-defined value whose magnitude is no greater than the smallest
normalized positive number in the specified type; if the integer expression
math_errhandling & MATH_ERRNO is nonzero, whether errno acquires the
- 204) The term underflow here is intended to encompass both ''gradual underflow'' as in IEC 60559 and
+ <sup><a name="note204" href="#note204"><b>204)</b></a></sup> The term underflow here is intended to encompass both ''gradual underflow'' as in IEC 60559 and
also ''flush-to-zero'' underflow.
[<a name="p215" href="#p215">page 215</a>] (<a href="#Contents">Contents</a>)
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.205)
+ Then classification is based on the type of the argument.<sup><a href="#note205"><b>205)</b></a></sup>
<b> Returns</b>
3 The fpclassify macro returns the value of the number classification macro
appropriate to the value of its argument.
- 205) Since an expression can be evaluated with more range and precision than its type has, it is important to
+ <sup><a name="note205" href="#note205"><b>205)</b></a></sup> 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.
<b> Description</b>
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.206)
+ Then determination is based on the type of the argument.<sup><a href="#note206"><b>206)</b></a></sup>
<b> Returns</b>
3 The isnan macro returns a nonzero value if and only if its argument has a NaN value.
<a name="7.12.3.5" href="#7.12.3.5"><b> 7.12.3.5 The isnormal macro</b></a>
- 206) For the isnan macro, the type for determination does not matter unless the implementation supports
+ <sup><a name="note206" href="#note206"><b>206)</b></a></sup> 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.
[<a name="p217" href="#p217">page 217</a>] (<a href="#Contents">Contents</a>)
1 #include <a href="#7.12"><math.h></a>
int signbit(real-floating x);
<b> Description</b>
-2 The signbit macro determines whether the sign of its argument value is negative.207)
+2 The signbit macro determines whether the sign of its argument value is negative.<sup><a href="#note207"><b>207)</b></a></sup>
<b> Returns</b>
3 The signbit macro returns a nonzero value if and only if the sign of its argument value
is negative.
- 207) The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
+ <sup><a name="note207" href="#note207"><b>207)</b></a></sup> The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
unsigned, it is treated as positive.
[<a name="p218" href="#p218">page 218</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
2 The expm1 functions compute the base-e exponential of the argument, minus 1. A range
- error occurs if x is too large.208)
+ error occurs if x is too large.<sup><a href="#note208"><b>208)</b></a></sup>
<b> Returns</b>
3 The expm1 functions return ex - 1.
<a name="7.12.6.4" href="#7.12.6.4"><b> 7.12.6.4 The frexp functions</b></a>
- 208) For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
+ <sup><a name="note208" href="#note208"><b>208)</b></a></sup> For small magnitude x, expm1(x) is expected to be more accurate than exp(x) - 1.
[<a name="p224" href="#p224">page 224</a>] (<a href="#Contents">Contents</a>)
float log1pf(float x);
long double log1pl(long double x);
<b> Description</b>
-2 The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.209)
+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.
<b> Returns</b>
- 209) For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
+ <sup><a name="note209" href="#note209"><b>209)</b></a></sup> For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
[<a name="p226" href="#p226">page 226</a>] (<a href="#Contents">Contents</a>)
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
<b> Description</b>
-2 The remainder functions compute the remainder x REM y required by IEC 60559.210)
+2 The remainder functions compute the remainder x REM y required by IEC 60559.<sup><a href="#note210"><b>210)</b></a></sup>
<b> Returns</b>
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.
- 210) ''When y != 0, the remainder r = x REM y is defined regardless of the rounding mode by the
+ <sup><a name="note210" href="#note210"><b>210)</b></a></sup> ''When y != 0, the remainder r = x REM y is defined regardless of the rounding mode by the
mathematical relation r = x - ny, where n is the integer nearest the exact value of x/y; whenever
| n - x/y | = 1/2, then n is even. Thus, the remainder is always exact. If r = 0, its sign shall be that of
x.'' This definition is applicable for all implementations.
<b> Description</b>
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.211) The nextafter functions return y if x equals y. A range error may occur
+ 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.
<b> Returns</b>
after x in the direction of y.
- 211) The argument values are converted to the type of the function, even by a macro implementation of the
+ <sup><a name="note211" href="#note211"><b>211)</b></a></sup> The argument values are converted to the type of the function, even by a macro implementation of the
function.
[<a name="p237" href="#p237">page 237</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
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.212)
+ type of the function if x equals y.<sup><a href="#note212"><b>212)</b></a></sup>
<a name="7.12.12" href="#7.12.12"><b> 7.12.12 Maximum, minimum, and positive difference functions</b></a>
<a name="7.12.12.1" href="#7.12.12.1"><b> 7.12.12.1 The fdim functions</b></a>
<b> Synopsis</b>
- 212) The result of the nexttoward functions is determined in the type of the function, without loss of
+ <sup><a name="note212" href="#note212"><b>212)</b></a></sup> 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.
[<a name="p238" href="#p238">page 238</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
-2 The fmax functions determine the maximum numeric value of their arguments.213)
+2 The fmax functions determine the maximum numeric value of their arguments.<sup><a href="#note213"><b>213)</b></a></sup>
<b> Returns</b>
3 The fmax functions return the maximum numeric value of their arguments.
<a name="7.12.12.3" href="#7.12.12.3"><b> 7.12.12.3 The fmin functions</b></a>
float fminf(float x, float y);
long double fminl(long double x, long double y);
<b> Description</b>
-2 The fmin functions determine the minimum numeric value of their arguments.214)
+2 The fmin functions determine the minimum numeric value of their arguments.<sup><a href="#note214"><b>214)</b></a></sup>
<b> Returns</b>
3 The fmin functions return the minimum numeric value of their arguments.
<a name="7.12.13" href="#7.12.13"><b> 7.12.13 Floating multiply-add</b></a>
- 213) NaN arguments are treated as missing data: if one argument is a NaN and the other numeric, then the
+ <sup><a name="note213" href="#note213"><b>213)</b></a></sup> 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>.
- 214) The fmin functions are analogous to the fmax functions in their treatment of NaNs.
+ <sup><a name="note214" href="#note214"><b>214)</b></a></sup> The fmin functions are analogous to the fmax functions in their treatment of NaNs.
[<a name="p239" href="#p239">page 239</a>] (<a href="#Contents">Contents</a>)
between numeric values. For any ordered pair of numeric values exactly one of the
relationships -- less, greater, and equal -- is true. Relational operators may raise the
''invalid'' floating-point exception when argument values are NaNs. For a NaN and a
- numeric value, or for two NaNs, just the unordered relationship is true.215) The following
+ numeric value, or for two NaNs, just the unordered relationship is true.<sup><a href="#note215"><b>215)</b></a></sup> The following
subclauses provide macros that are quiet (non floating-point exception raising) versions
of the relational operators, and other comparison macros that facilitate writing efficient
code that accounts for NaNs without suffering the ''invalid'' floating-point exception. In
- 215) IEC 60559 requires that the built-in relational operators raise the ''invalid'' floating-point exception if
+ <sup><a name="note215" href="#note215"><b>215)</b></a></sup> 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.
<a name="7.13" href="#7.13"><b> 7.13 Nonlocal jumps <setjmp.h></b></a>
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.216)
+ one type, for bypassing the normal function call and return discipline.<sup><a href="#note216"><b>216)</b></a></sup>
2 The type declared is
jmp_buf
which is an array type suitable for holding the information needed to restore a calling
constant expression, with the resulting expression being the entire controlling
- 216) These functions are useful for dealing with unusual conditions encountered in a low-level function of
+ <sup><a name="note216" href="#note216"><b>216)</b></a></sup> These functions are useful for dealing with unusual conditions encountered in a low-level function of
a program.
[<a name="p243" href="#p243">page 243</a>] (<a href="#Contents">Contents</a>)
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
jmp_buf argument. If there has been no such invocation, or if the function containing
- the invocation of the setjmp macro has terminated execution217) in the interim, or if the
+ the invocation of the setjmp macro has terminated execution<sup><a href="#note217"><b>217)</b></a></sup> in the interim, or if the
invocation of the setjmp macro was within the scope of an identifier with variably
modified type and execution has left that scope in the interim, the behavior is undefined.
-3 All accessible objects have values, and all other components of the abstract machine218)
+3 All accessible objects have values, and all other components of the abstract machine<sup><a href="#note218"><b>218)</b></a></sup>
have state, as of the time the longjmp function was called, except that the values of
objects of automatic storage duration that are local to the function containing the
invocation of the corresponding setjmp macro that do not have volatile-qualified type
- 217) For example, by executing a return statement or because another longjmp call has caused a
+ <sup><a name="note217" href="#note217"><b>217)</b></a></sup> For example, by executing a return statement or because another longjmp call has caused a
transfer to a setjmp invocation in a function earlier in the set of nested calls.
- 218) This includes, but is not limited to, the floating-point status flags and the state of open files.
+ <sup><a name="note218" href="#note218"><b>218)</b></a></sup> This includes, but is not limited to, the floating-point status flags and the state of open files.
[<a name="p244" href="#p244">page 244</a>] (<a href="#Contents">Contents</a>)
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
- letter or with SIG_ and an uppercase letter,219) may also be specified by the
+ letter or with SIG_ and an uppercase letter,<sup><a href="#note219"><b>219)</b></a></sup> may also be specified by the
implementation. The complete set of signals, their semantics, and their default handling
is implementation-defined; all signal numbers shall be positive.
-
219) See ''future library directions'' (<a href="#7.26.9">7.26.9</a>). The names of the signal numbers reflect the following terms
+
<sup><a name="note219" href="#note219"><b>219)</b></a></sup> 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.
function, the _Exit function, or the signal function with the first argument equal to
the signal number corresponding to the signal that caused the invocation of the handler.
Furthermore, if such a call to the signal function results in a SIG_ERR return, the
- value of errno is indeterminate.220)
+ value of errno is indeterminate.<sup><a href="#note220"><b>220)</b></a></sup>
6 At program startup, the equivalent of
signal(sig, SIG_IGN);
- 220) If any signal is generated by an asynchronous signal handler, the behavior is undefined.
+ <sup><a name="note220" href="#note220"><b>220)</b></a></sup> If any signal is generated by an asynchronous signal handler, the behavior is undefined.
[<a name="p247" href="#p247">page 247</a>] (<a href="#Contents">Contents</a>)
subclause) having type va_list. The object ap may be passed as an argument to
another function; if that function invokes the va_arg macro with parameter ap, the
value of ap in the calling function is indeterminate and shall be passed to the va_end
- macro prior to any further reference to ap.221)
+ macro prior to any further reference to ap.<sup><a href="#note221"><b>221)</b></a></sup>
<a name="7.15.1" href="#7.15.1"><b> 7.15.1 Variable argument list access macros</b></a>
1 The va_start and va_arg macros described in this subclause shall be implemented
as macros, not functions. It is unspecified whether va_copy and va_end are macros or
the next argument in the call. The parameter ap shall have been initialized by the
va_start or va_copy macro (without an intervening invocation of the va_end
- 221) It is permitted to create a pointer to a va_list and pass that pointer to another function, in which
+ <sup><a name="note221" href="#note221"><b>221)</b></a></sup> 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.
[<a name="p249" href="#p249">page 249</a>] (<a href="#Contents">Contents</a>)
__bool_true_false_are_defined
which expands to the integer constant 1.
4 Notwithstanding the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and perhaps then
- redefine the macros bool, true, and false.222)
+ redefine the macros bool, true, and false.<sup><a href="#note222"><b>222)</b></a></sup>
-
222) See ''future library directions'' (<a href="#7.26.7">7.26.7</a>).
+
<sup><a name="note222" href="#note222"><b>222)</b></a></sup> See ''future library directions'' (<a href="#7.26.7">7.26.7</a>).
[<a name="p253" href="#p253">page 253</a>] (<a href="#Contents">Contents</a>)
<a name="7.18" href="#7.18"><b> 7.18 Integer types <stdint.h></b></a>
1 The header <a href="#7.18"><stdint.h></a> declares sets of integer types having specified widths, and
- defines corresponding sets of macros.223) It also defines macros that specify limits of
+ defines corresponding sets of macros.<sup><a href="#note223"><b>223)</b></a></sup> It also defines macros that specify limits of
integer types corresponding to types defined in other standard headers.
2 Types are defined in the following categories:
-- integer types having certain exact widths;
(Some of these types may denote the same type.)
3 Corresponding macros specify limits of the declared types and construct suitable
constants.
-4 For each type described herein that the implementation provides,
224) <a href="#7.18"><stdint.h></a> shall
+4 For each type described herein that the implementation provides,
<sup><a href="#note224"><b>224)</b></a></sup> <a href="#7.18"><stdint.h></a> shall
declare that typedef name and define the associated macros. Conversely, for each type
described herein that the implementation does not provide, <a href="#7.18"><stdint.h></a> shall not
declare that typedef name nor shall it define the associated macros. An implementation
-
223) See ''future library directions'' (<a href="#7.26.8">7.26.8</a>).
- 224) Some of these types may denote implementation-defined extended integer types.
+
<sup><a name="note223" href="#note223"><b>223)</b></a></sup> See ''future library directions'' (<a href="#7.26.8">7.26.8</a>).
+ <sup><a name="note224" href="#note224"><b>224)</b></a></sup> Some of these types may denote implementation-defined extended integer types.
[<a name="p255" href="#p255">page 255</a>] (<a href="#Contents">Contents</a>)
int_least64_t uint_least64_t
All other types of this form are optional.
<a name="7.18.1.3" href="#7.18.1.3"><b> 7.18.1.3 Fastest minimum-width integer types</b></a>
-1 Each of the following types designates an integer type that is usually fastest225) to operate
+1 Each of the following types designates an integer type that is usually fastest<sup><a href="#note225"><b>225)</b></a></sup> to operate
with among all integer types that have at least the specified width.
2 The typedef name int_fastN_t designates the fastest signed integer type with a width
of at least N . The typedef name uint_fastN_t designates the fastest unsigned integer
- 225) The designated type is not guaranteed to be fastest for all purposes; if the implementation has no clear
+ <sup><a name="note225" href="#note225"><b>225)</b></a></sup> 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.
uintmax_t
These types are required.
<a name="7.18.2" href="#7.18.2"><b> 7.18.2 Limits of specified-width integer types</b></a>
-1 The following object-like macros226) specify the minimum and maximum limits of the
+1 The following object-like macros<sup><a href="#note226"><b>226)</b></a></sup> specify the minimum and maximum limits of the
types declared in <a href="#7.18"><stdint.h></a>. Each macro name corresponds to a similar type name in
<a href="#7.18.1">7.18.1</a>.
2 Each instance of any defined macro shall be replaced by a constant expression suitable
for use in #if preprocessing directives, and this expression shall have the same type as
would an expression that is an object of the corresponding type converted according to
- 226) C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
+ <sup><a name="note226" href="#note226"><b>226)</b></a></sup> C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
before <a href="#7.18"><stdint.h></a> is included.
[<a name="p257" href="#p257">page 257</a>] (<a href="#Contents">Contents</a>)
-- maximum value of greatest-width unsigned integer type
UINTMAX_MAX 264 - 1
<a name="7.18.3" href="#7.18.3"><b> 7.18.3 Limits of other integer types</b></a>
-1 The following object-like macros227) specify the minimum and maximum limits of
+1 The following object-like macros<sup><a href="#note227"><b>227)</b></a></sup> specify the minimum and maximum limits of
integer types corresponding to types defined in other standard headers.
2 Each instance of these macros shall be replaced by a constant expression suitable for use
in #if preprocessing directives, and this expression shall have the same type as would an
promotions. Its implementation-defined value shall be equal to or greater in magnitude
(absolute value) than the corresponding value given below, with the same sign. An
implementation shall define only the macros corresponding to those typedef names it
- actually provides.228)
+ actually provides.<sup><a href="#note228"><b>228)</b></a></sup>
-- limits of ptrdiff_t
PTRDIFF_MIN -65535
PTRDIFF_MAX +65535
- 227) C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
+ <sup><a name="note227" href="#note227"><b>227)</b></a></sup> C++ implementations should define these macros only when __STDC_LIMIT_MACROS is defined
before <a href="#7.18"><stdint.h></a> is included.
- 228) A freestanding implementation need not provide all of these types.
+ <sup><a name="note228" href="#note228"><b>228)</b></a></sup> A freestanding implementation need not provide all of these types.
[<a name="p259" href="#p259">page 259</a>] (<a href="#Contents">Contents</a>)
4 If wchar_t (see <a href="#7.17">7.17</a>) is defined as a signed integer type, the value of WCHAR_MIN
shall be no greater than -127 and the value of WCHAR_MAX shall be no less than 127;
otherwise, wchar_t is defined as an unsigned integer type, and the value of
- WCHAR_MIN shall be 0 and the value of WCHAR_MAX shall be no less than 255.229)
+ WCHAR_MIN shall be 0 and the value of WCHAR_MAX shall be no less than 255.<sup><a href="#note229"><b>229)</b></a></sup>
5 If wint_t (see <a href="#7.24">7.24</a>) is defined as a signed integer type, the value of WINT_MIN shall
be no greater than -32767 and the value of WINT_MAX shall be no less than 32767;
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.
<a name="7.18.4" href="#7.18.4"><b> 7.18.4 Macros for integer constants</b></a>
-1 The following function-like macros230) expand to integer constants suitable for
+1 The following function-like macros<sup><a href="#note230"><b>230)</b></a></sup> expand to integer constants suitable for
initializing objects that have integer types corresponding to types defined in
<a href="#7.18"><stdint.h></a>. Each macro name corresponds to a similar type name in <a href="#7.18.1.2">7.18.1.2</a> or
<a href="#7.18.1.5">7.18.1.5</a>.
- 229) The values WCHAR_MIN and WCHAR_MAX do not necessarily correspond to members of the extended
+ <sup><a name="note229" href="#note229"><b>229)</b></a></sup> The values WCHAR_MIN and WCHAR_MAX do not necessarily correspond to members of the extended
character set.
- 230) C++ implementations should define these macros only when __STDC_CONSTANT_MACROS is
+ <sup><a name="note230" href="#note230"><b>230)</b></a></sup> C++ implementations should define these macros only when __STDC_CONSTANT_MACROS is
defined before <a href="#7.18"><stdint.h></a> is included.
[<a name="p260" href="#p260">page 260</a>] (<a href="#Contents">Contents</a>)
[<a name="p262" href="#p262">page 262</a>] (<a href="#Contents">Contents</a>)
- guarantees can be opened;231)
+ guarantees can be opened;<sup><a href="#note231"><b>231)</b></a></sup>
L_tmpnam
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold a temporary file name string generated by the tmpnam
putwchar, fwprintf, wprintf, vfwprintf, and vwprintf.
- 231) If the implementation imposes no practical limit on the length of file name strings, the value of
+ <sup><a name="note231" href="#note231"><b>231)</b></a></sup> If the implementation imposes no practical limit on the length of file name strings, the value of
FILENAME_MAX should instead be the recommended size of an array intended to hold a file name
string. Of course, file name string contents are subject to other system-specific constraints; therefore
all possible strings of length FILENAME_MAX cannot be expected to be opened successfully.
or whether to or from files supported on structured storage devices, are mapped into
logical data streams, whose properties are more uniform than their various inputs and
outputs. Two forms of mapping are supported, for text streams and for binary
- streams.232)
+ streams.<sup><a href="#note232"><b>232)</b></a></sup>
2 A text stream is an ordered sequence of characters composed into lines, each line
consisting of zero or more characters plus a terminating new-line character. Whether the
last line requires a terminating new-line character is implementation-defined. Characters
character input/output function has been applied to a stream without orientation, the
- 232) An implementation need not distinguish between text streams and binary streams. In such an
+ <sup><a name="note232" href="#note232"><b>232)</b></a></sup> 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.
stream becomes a wide-oriented stream. Similarly, once a byte input/output function has
been applied to a stream without orientation, the stream becomes a byte-oriented stream.
Only a call to the freopen function or the fwide function can otherwise alter the
- orientation of a stream. (A successful call to freopen removes any orientation.)233)
+ orientation of a stream. (A successful call to freopen removes any orientation.)<sup><a href="#note233"><b>233)</b></a></sup>
5 Byte input/output functions shall not be applied to a wide-oriented stream and wide
character input/output functions shall not be applied to a byte-oriented stream. The
remaining stream operations do not affect, and are not affected by, a stream's orientation,
- 233) The three predefined streams stdin, stdout, and stderr are unoriented at program startup.
+ <sup><a name="note233" href="#note233"><b>233)</b></a></sup> The three predefined streams stdin, stdout, and stderr are unoriented at program startup.
[<a name="p265" href="#p265">page 265</a>] (<a href="#Contents">Contents</a>)
multibyte characters, generalized as follows:
-- Multibyte encodings within files may contain embedded null bytes (unlike multibyte
encodings valid for use internal to the program).
- -- A file need not begin nor end in the initial shift state.234)
+ -- A file need not begin nor end in the initial shift state.<sup><a href="#note234"><b>234)</b></a></sup>
10 Moreover, the encodings used for multibyte characters may differ among files. Both the
nature and choice of such encodings are implementation-defined.
11 The wide character input functions read multibyte characters from the stream and convert
value passed to the underlying wcrtomb does not correspond to a valid (generalized)
- 234) Setting the file position indicator to end-of-file, as with fseek(file, 0, SEEK_END), has
+ <sup><a name="note234" href="#note234"><b>234)</b></a></sup> 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.
[<a name="p268" href="#p268">page 268</a>] (<a href="#Contents">Contents</a>)
<b> Returns</b>
-3 The rename function returns zero if the operation succeeds, nonzero if it fails,235) in
+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.
<a name="7.19.4.3" href="#7.19.4.3"><b> 7.19.4.3 The tmpfile function</b></a>
<b> Synopsis</b>
char *tmpnam(char *s);
<b> Description</b>
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.236) The function is potentially capable of generating
+ as the name of an existing file.<sup><a href="#note236"><b>236)</b></a></sup> The function is potentially capable of generating
- 235) Among the reasons the implementation may cause the rename function to fail are that the file is open
+ <sup><a name="note235" href="#note235"><b>235)</b></a></sup> 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.
- 236) Files created using strings generated by the tmpnam function are temporary only in the sense that
+ <sup><a name="note236" href="#note236"><b>236)</b></a></sup> Files created using strings generated by the tmpnam function are temporary only in the sense that
their names should not collide with those generated by conventional naming rules for the
implementation. It is still necessary to use the remove function to remove such files when their use
is ended, and before program termination.
2 The fopen function opens the file whose name is the string pointed to by filename,
and associates a stream with it.
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.237)
+ 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
- 237) If the string begins with one of the above sequences, the implementation might choose to ignore the
+ <sup><a name="note237" href="#note237"><b>237)</b></a></sup> 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>).
[<a name="p272" href="#p272">page 272</a>] (<a href="#Contents">Contents</a>)
- as in the fopen function.238)
+ as in the fopen function.<sup><a href="#note238"><b>238)</b></a></sup>
3 If filename is a null pointer, the freopen function attempts to change the mode of
the stream to that specified by mode, as if the name of the file currently associated with
the stream had been used. It is implementation-defined which changes of mode are
- 238) The primary use of the freopen function is to change the file associated with a standard text stream
+ <sup><a name="note238" href="#note238"><b>238)</b></a></sup> 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.
determines how stream will be buffered, as follows: _IOFBF causes input/output to be
fully buffered; _IOLBF causes input/output to be line buffered; _IONBF causes
input/output to be unbuffered. If buf is not a null pointer, the array it points to may be
- used instead of a buffer allocated by the setvbuf function239) and the argument size
+ used instead of a buffer allocated by the setvbuf function<sup><a href="#note239"><b>239)</b></a></sup> and the argument size
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.
for mode or if the request cannot be honored.
<a name="7.19.6" href="#7.19.6"><b> 7.19.6 Formatted input/output functions</b></a>
1 The formatted input/output functions shall behave as if there is a sequence point after the
- actions associated with each specifier.240)
+ actions associated with each specifier.<sup><a href="#note240"><b>240)</b></a></sup>
<a name="7.19.6.1" href="#7.19.6.1"><b> 7.19.6.1 The fprintf function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.19"><stdio.h></a>
characters (not %), which are copied unchanged to the output stream; and conversion
- 239) The buffer has to have a lifetime at least as great as the open stream, so the stream should be closed
+ <sup><a name="note239" href="#note239"><b>239)</b></a></sup> 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.
- 240) The fprintf functions perform writes to memory for the %n specifier.
+ <sup><a name="note240" href="#note240"><b>240)</b></a></sup> The fprintf functions perform writes to memory for the %n specifier.
[<a name="p274" href="#p274">page 274</a>] (<a href="#Contents">Contents</a>)
-- An optional minimum field width. If the converted value has fewer characters than the
field width, it is padded with spaces (by default) on the left (or right, if the left
adjustment flag, described later, has been given) to the field width. The field width
- takes the form of an asterisk * (described later) or a nonnegative decimal integer.241)
+ takes the form of an asterisk * (described later) or a nonnegative decimal integer.<sup><a href="#note241"><b>241)</b></a></sup>
-- An optional precision that gives the minimum number of digits to appear for the d, i,
o, u, x, and X conversions, the number of digits to appear after the decimal-point
character for a, A, e, E, f, and F conversions, the maximum number of significant
- 241) Note that 0 is taken as a flag, not as the beginning of a field width.
+ <sup><a name="note241" href="#note241"><b>241)</b></a></sup> Note that 0 is taken as a flag, not as the beginning of a field width.
[<a name="p275" href="#p275">page 275</a>] (<a href="#Contents">Contents</a>)
- specified.)242)
+ specified.)<sup><a href="#note242"><b>242)</b></a></sup>
space 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.
long int or unsigned long int argument; that a following n
conversion specifier applies to a pointer to a long int argument; that a
- 242) The results of all floating conversions of a negative zero, and of negative values that round to zero,
+ <sup><a name="note242" href="#note242"><b>242)</b></a></sup> The results of all floating conversions of a negative zero, and of negative values that round to zero,
include a minus sign.
[<a name="p276" href="#p276">page 276</a>] (<a href="#Contents">Contents</a>)
[-]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.243)
+ respectively.<sup><a href="#note243"><b>243)</b></a></sup>
e,E 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
-- 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
-243) When applied to infinite and NaN values, the -, +, and space flag characters have their usual meaning;
+<sup><a name="note243" href="#note243"><b>243)</b></a></sup> When applied to infinite and NaN values, the -, +, and space flag characters have their usual meaning;
the # and 0 flag characters have no effect.
[<a name="p278" href="#p278">page 278</a>] (<a href="#Contents">Contents</a>)
a,A 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 character244) and the number
+ otherwise unspecified) before the decimal-point character<sup><a href="#note244"><b>244)</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 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
- distinguish245) values of type double, except that trailing zeros may be
+ distinguish<sup><a href="#note245"><b>245)</b></a></sup> values of type double, except that trailing zeros may be
omitted; if the precision is zero and the # flag is not specified, no decimal-
point character appears. The letters abcdef are used for a conversion and
the letters ABCDEF for A conversion. The A conversion specifier produces a
containing the wint_t argument to the lc conversion specification and the
second a null wide character.
s If no l length modifier is present, the argument shall be a pointer to the initial
- element of an array of character type.246) Characters from the array are
+ element of an array of character type.<sup><a href="#note246"><b>246)</b></a></sup> Characters from the array are
-244) Binary implementations can choose the hexadecimal digit to the left of the decimal-point character so
+<sup><a name="note244" href="#note244"><b>244)</b></a></sup> Binary implementations can choose the hexadecimal digit to the left of the decimal-point character so
that subsequent digits align to nibble (4-bit) boundaries.
-245) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
+<sup><a name="note245" href="#note245"><b>245)</b></a></sup> The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p
might suffice depending on the implementation's scheme for determining the digit to the left of the
decimal-point character.
-246) No special provisions are made for multibyte characters.
+<sup><a name="note246" href="#note246"><b>246)</b></a></sup> No special provisions are made for multibyte characters.
[<a name="p279" href="#p279">page 279</a>] (<a href="#Contents">Contents</a>)
written (including shift sequences, if any), and the array shall contain a null
wide character if, to equal the multibyte character sequence length given by
the precision, the function would need to access a wide character one past the
- end of the array. In no case is a partial multibyte character written.247)
+ end of the array. In no case is a partial multibyte character written.<sup><a href="#note247"><b>247)</b></a></sup>
p 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.
undefined.
% A % character is written. No argument is converted. The complete
conversion specification shall be %%.
-9 If a conversion specification is invalid, the behavior is undefined.248) If any argument is
+9 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.
10 In no case does a nonexistent or small field width cause truncation of a field; if the result
- 247) Redundant shift sequences may result if multibyte characters have a state-dependent encoding.
-
248) See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
+ <sup><a name="note247" href="#note247"><b>247)</b></a></sup> Redundant shift sequences may result if multibyte characters have a state-dependent encoding.
+
<sup><a name="note248" href="#note248"><b>248)</b></a></sup> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
[<a name="p280" href="#p280">page 280</a>] (<a href="#Contents">Contents</a>)
in hexadecimal floating style with the given precision, with the extra stipulation that the
error should have a correct sign for the current rounding direction.
13 For e, E, f, F, g, and G conversions, if the number of significant decimal digits is at most
- DECIMAL_DIG, then the result should be correctly rounded.249) If the number of
+ DECIMAL_DIG, then the result should be correctly rounded.<sup><a href="#note249"><b>249)</b></a></sup> If the number of
significant decimal digits is more than DECIMAL_DIG but the source value is exactly
representable with DECIMAL_DIG digits, then the result should be an exact
representation with trailing zeros. Otherwise, the source value is bounded by two
- 249) For binary-to-decimal conversion, the result format's values are the numbers representable with the
+ <sup><a name="note249" href="#note249"><b>249)</b></a></sup> For binary-to-decimal conversion, the result format's values are the numbers representable with the
given format specifier. The number of significant digits is determined by the format specifier, and in
the case of fixed-point conversion by the source value as well.
described below for each specifier. A conversion specification is executed in the
following steps:
8 Input white-space characters (as specified by the isspace function) are skipped, unless
- the specification includes a [, c, or n specifier.250)
+ the specification includes a [, c, or n specifier.<sup><a href="#note250"><b>250)</b></a></sup>
9 An input item is read from the stream, unless the specification includes an n specifier. An
input item is defined as the longest sequence of input characters which does not exceed
- any specified field width and which is, or is a prefix of, a matching input sequence.251)
+ any specified field width and which is, or is a prefix of, a matching input sequence.<sup><a href="#note251"><b>251)</b></a></sup>
The first character, if any, after the input item remains unread. If the length of the input
item is zero, the execution of the directive fails; this condition is a matching failure unless
end-of-file, an encoding error, or a read error prevented input from the stream, in which
does not have an appropriate type, or if the result of the conversion cannot be represented
- 250) These white-space characters are not counted against a specified field width.
- 251) fscanf pushes back at most one input character onto the input stream. Therefore, some sequences
+ <sup><a name="note250" href="#note250"><b>250)</b></a></sup> These white-space characters are not counted against a specified field width.
+ <sup><a name="note251" href="#note251"><b>251)</b></a></sup> fscanf pushes back at most one input character onto the input stream. Therefore, some sequences
that are acceptable to strtod, strtol, etc., are unacceptable to fscanf.
[<a name="p283" href="#p283">page 283</a>] (<a href="#Contents">Contents</a>)
format is the same as expected for the subject sequence of the strtod
function. The corresponding argument shall be a pointer to floating.
c Matches a sequence of characters of exactly the number specified by the field
- width (1 if no field width is present in the directive).252)
+ 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
sequence. No null character is added.
If an l length modifier is present, the input shall be a sequence of multibyte
-252) No special provisions are made for multibyte characters in the matching rules used by the c, s, and [
+<sup><a name="note252" href="#note252"><b>252)</b></a></sup> No special provisions are made for multibyte characters in the matching rules used by the c, s, and [
conversion specifiers -- the extent of the input field is determined on a byte-by-byte basis. The
resulting field is nevertheless a sequence of multibyte characters that begins in the initial shift state.
suppressing character or a field width, the behavior is undefined.
% Matches a single % character; no conversion or assignment occurs. The
complete conversion specification shall be %%.
-13 If a conversion specification is invalid, the behavior is undefined.253)
+13 If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note253"><b>253)</b></a></sup>
14 The conversion specifiers A, E, F, G, and X are also valid and behave the same as,
respectively, a, e, f, g, and x.
15 Trailing white space (including new-line characters) is left unread unless matched by a
-
253) See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
+
<sup><a name="note253" href="#note253"><b>253)</b></a></sup> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
[<a name="p287" href="#p287">page 287</a>] (<a href="#Contents">Contents</a>)
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.254)
+ va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<b> Returns</b>
3 The vfprintf function returns the number of characters transmitted, or a negative
value if an output or encoding error occurred.
- 254) As the functions vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf, and
+ <sup><a name="note254" href="#note254"><b>254)</b></a></sup> 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.
[<a name="p292" href="#p292">page 292</a>] (<a href="#Contents">Contents</a>)
of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
fgetc function returns the next character from the input stream pointed to by stream.
If a read error occurs, the error indicator for the stream is set and the fgetc function
- returns EOF.255)
+ returns EOF.<sup><a href="#note255"><b>255)</b></a></sup>
<a name="7.19.7.2" href="#7.19.7.2"><b> 7.19.7.2 The fgets function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.19"><stdio.h></a>
- 255) An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
+ <sup><a name="note255" href="#note255"><b>255)</b></a></sup> An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
[<a name="p296" href="#p296">page 296</a>] (<a href="#Contents">Contents</a>)
ungetc function is unspecified until all pushed-back characters are read or discarded.
For a binary stream, its file position indicator is decremented by each successful call to
the ungetc function; if its value was zero before a call, it is indeterminate after the
- call.256)
+ call.<sup><a href="#note256"><b>256)</b></a></sup>
<b> Returns</b>
6 The ungetc function returns the character pushed back after conversion, or EOF if the
operation fails.
-
256) See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
+
<sup><a name="note256" href="#note256"><b>256)</b></a></sup> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
[<a name="p300" href="#p300">page 300</a>] (<a href="#Contents">Contents</a>)
<a name="7.20" href="#7.20"><b> 7.20 General utilities <stdlib.h></b></a>
1 The header <a href="#7.20"><stdlib.h></a> declares five types and several functions of general utility, and
- defines several macros.257)
+ defines several macros.<sup><a href="#note257"><b>257)</b></a></sup>
2 The types declared are size_t and wchar_t (both described in <a href="#7.17">7.17</a>),
div_t
which is a structure type that is the type of the value returned by the div function,
-
257) See ''future library directions'' (<a href="#7.26.10">7.26.10</a>).
+
<sup><a name="note257" href="#note257"><b>257)</b></a></sup> See ''future library directions'' (<a href="#7.26.10">7.26.10</a>).
[<a name="p306" href="#p306">page 306</a>] (<a href="#Contents">Contents</a>)
nor a decimal-point character appears in a decimal floating point number, or if a binary
exponent part does not appear in a hexadecimal floating point number, an exponent part
of the appropriate type with value zero is assumed to follow the last digit in the string. If
- the subject sequence begins with a minus sign, the sequence is interpreted as negated.258)
+ 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
NaN, if supported in the return type, else like a subject sequence part that does not have
- the expected form; the meaning of the n-char sequences is implementation-defined.259) A
+ 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
endptr is not a null pointer.
5 If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
The result should be one of the (equal or adjacent) values that would be obtained by
correctly rounding L and U according to the current rounding direction, with the extra
- 258) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
+ <sup><a name="note258" href="#note258"><b>258)</b></a></sup> 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,
the functions honor the sign of zero if floating-point arithmetic supports signed zeros.
- 259) An implementation may use the n-char sequence to determine extra information to be represented in
+ <sup><a name="note259" href="#note259"><b>259)</b></a></sup> An implementation may use the n-char sequence to determine extra information to be represented in
the NaN's significand.
[<a name="p309" href="#p309">page 309</a>] (<a href="#Contents">Contents</a>)
stipulation that the error with respect to D should have a correct sign for the current
- rounding direction.260)
+ rounding direction.<sup><a href="#note260"><b>260)</b></a></sup>
<b> Returns</b>
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
white-space characters (as specified by the isspace function), a subject sequence
-
260) DECIMAL_DIG, defined in <a href="#7.7"><float.h></a>, should be sufficiently large that L and U will usually round
+
<sup><a name="note260" href="#note260"><b>260)</b></a></sup> DECIMAL_DIG, defined in <a href="#7.7"><float.h></a>, should be sufficiently large that L and U will usually round
to the same internal floating value, but if not will round to adjacent values.
[<a name="p310" href="#p310">page 310</a>] (<a href="#Contents">Contents</a>)
void *calloc(size_t nmemb, size_t size);
<b> Description</b>
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.261)
+ is size. The space is initialized to all bits zero.<sup><a href="#note261"><b>261)</b></a></sup>
<b> Returns</b>
3 The calloc function returns either a null pointer or a pointer to the allocated space.
<a name="7.20.3.2" href="#7.20.3.2"><b> 7.20.3.2 The free function</b></a>
the argument does not match a pointer earlier returned by the calloc, malloc, or
- 261) Note that this need not be the same as the representation of floating-point zero or a null pointer
+ <sup><a name="note261" href="#note261"><b>261)</b></a></sup> Note that this need not be the same as the representation of floating-point zero or a null pointer
constant.
[<a name="p313" href="#p313">page 313</a>] (<a href="#Contents">Contents</a>)
[<a name="p315" href="#p315">page 315</a>] (<a href="#Contents">Contents</a>)
3 First, all functions registered by the atexit function are called, in the reverse order of
- their registration,262) except that a function is called after any previously registered
+ their registration,<sup><a href="#note262"><b>262)</b></a></sup> except that a function is called after any previously registered
functions that had already been called at the time it was registered. If, during the call to
any such function, a call to the longjmp function is made that would terminate the call
to the registered function, the behavior is undefined.
- 262) Each function is called as many times as it was registered, and in the correct order with respect to
+ <sup><a name="note262" href="#note262"><b>262)</b></a></sup> Each function is called as many times as it was registered, and in the correct order with respect to
other registered functions.
[<a name="p316" href="#p316">page 316</a>] (<a href="#Contents">Contents</a>)
in <a href="#7.1.4">7.1.4</a>.
2 The implementation shall ensure that the second argument of the comparison function
(when called from bsearch), or both arguments (when called from qsort), are
- pointers to elements of the array.263) The first argument when called from bsearch
+ pointers to elements of the array.<sup><a href="#note263"><b>263)</b></a></sup> The first argument when called from bsearch
shall equal key.
3 The comparison function shall not alter the contents of the array. The implementation
may reorder elements of the array between calls to the comparison function, but shall not
is pointed to by base, for an element that matches the object pointed to by key. The
- 263) That is, if the value passed is p, then the following expressions are always nonzero:
+ <sup><a name="note263" href="#note263"><b>263)</b></a></sup> That is, if the value passed is p, then the following expressions are always nonzero:
((char *)p - (char *)base) % size == 0
(char *)p >= (char *)base
(char *)p < (char *)base + nmemb * size
integer less than, equal to, or greater than zero if the key object is considered,
respectively, to be less than, to match, or to be greater than the array element. The array
shall consist of: all the elements that compare less than, all the elements that compare
- equal to, and all the elements that compare greater than the key object, in that order.264)
+ 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>
<b> Returns</b>
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
- 264) In practice, the entire array is sorted according to the comparison function.
+ <sup><a name="note264" href="#note264"><b>264)</b></a></sup> In practice, the entire array is sorted according to the comparison function.
[<a name="p319" href="#p319">page 319</a>] (<a href="#Contents">Contents</a>)
long long int llabs(long long int j);
<b> Description</b>
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.265)
+ result cannot be represented, the behavior is undefined.<sup><a href="#note265"><b>265)</b></a></sup>
<b> Returns</b>
3 The abs, labs, and llabs, functions return the absolute value.
<a name="7.20.6.2" href="#7.20.6.2"><b> 7.20.6.2 The div, ldiv, and lldiv functions</b></a>
- 265) The absolute value of the most negative number cannot be represented in two's complement.
+ <sup><a name="note265" href="#note265"><b>265)</b></a></sup> The absolute value of the most negative number cannot be represented in two's complement.
[<a name="p320" href="#p320">page 320</a>] (<a href="#Contents">Contents</a>)
pointer. Subsequent calls with s as other than a null pointer cause the internal conversion
state of the function to be altered as necessary. A call with s as a null pointer causes
these functions to return a nonzero value if encodings have state dependency, and zero
- otherwise.266) Changing the LC_CTYPE category causes the conversion state of these
+ 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.
<a name="7.20.7.1" href="#7.20.7.1"><b> 7.20.7.1 The mblen function</b></a>
<b> Synopsis</b>
- 266) If the locale employs special bytes to change the shift state, these bytes do not produce separate wide
+ <sup><a name="note266" href="#note266"><b>266)</b></a></sup> 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.
[<a name="p321" href="#p321">page 321</a>] (<a href="#Contents">Contents</a>)
<b> Returns</b>
4 If an invalid multibyte character is encountered, the mbstowcs function returns
(size_t)(-1). Otherwise, the mbstowcs function returns the number of array
- elements modified, not including a terminating null wide character, if any.267)
+ elements modified, not including a terminating null wide character, if any.<sup><a href="#note267"><b>267)</b></a></sup>
- 267) The array will not be null-terminated if the value returned is n.
+ <sup><a name="note267" href="#note267"><b>267)</b></a></sup> The array will not be null-terminated if the value returned is n.
[<a name="p323" href="#p323">page 323</a>] (<a href="#Contents">Contents</a>)
<a name="7.21.1" href="#7.21.1"><b> 7.21.1 String function conventions</b></a>
1 The header <a href="#7.21"><string.h></a> declares one type and several functions, and defines one
macro useful for manipulating arrays of character type and other objects treated as arrays
- of character type.268) The type is size_t and the macro is NULL (both described in
+ of character type.<sup><a href="#note268"><b>268)</b></a></sup> The type is size_t and the macro is NULL (both described in
<a name="7.17)" href="#7.17)"><b> 7.17). Various methods are used for determining the lengths of the arrays, but in all cases</b></a>
a char * or void * argument points to the initial (lowest addressed) character of the
array. If an array is accessed beyond the end of an object, the behavior is undefined.
-
268) See ''future library directions'' (<a href="#7.26.11">7.26.11</a>).
+
<sup><a name="note268" href="#note268"><b>268)</b></a></sup> See ''future library directions'' (<a href="#7.26.11">7.26.11</a>).
[<a name="p325" href="#p325">page 325</a>] (<a href="#Contents">Contents</a>)
[<a name="p326" href="#p326">page 326</a>] (<a href="#Contents">Contents</a>)
- s1.269) If copying takes place between objects that overlap, the behavior is undefined.
+ s1.<sup><a href="#note269"><b>269)</b></a></sup> If copying takes place between objects that overlap, the behavior is undefined.
3 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.
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
the string pointed to by s1. The initial character of s2 overwrites the null character at the
- end of s1. A terminating null character is always appended to the result.270) If copying
+ end of s1. A terminating null character is always appended to the result.<sup><a href="#note270"><b>270)</b></a></sup> If copying
- 269) Thus, if there is no null character in the first n characters of the array pointed to by s2, the result will
+ <sup><a name="note269" href="#note269"><b>269)</b></a></sup> 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.
- 270) Thus, the maximum number of characters that can end up in the array pointed to by s1 is
+ <sup><a name="note270" href="#note270"><b>270)</b></a></sup> Thus, the maximum number of characters that can end up in the array pointed to by s1 is
strlen(s1)+n+1.
[<a name="p327" href="#p327">page 327</a>] (<a href="#Contents">Contents</a>)
int memcmp(const void *s1, const void *s2, size_t n);
<b> Description</b>
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 s2.271)
+ the first n characters of the object pointed to by s2.<sup><a href="#note271"><b>271)</b></a></sup>
<b> Returns</b>
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
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
- 271) The contents of ''holes'' used as padding for purposes of alignment within structure objects are
+ <sup><a name="note271" href="#note271"><b>271)</b></a></sup> 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.
2 Of the <a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> functions without an f (float) or l (long
double) suffix, several have one or more parameters whose corresponding real type is
double. For each such function, except modf, there is a corresponding type-generic
- macro.272) The parameters whose corresponding real type is double in the function
+ macro.<sup><a href="#note272"><b>272)</b></a></sup> The parameters whose corresponding real type is double in the function
synopsis are generic parameters. Use of the macro invokes a function whose
corresponding real type and type domain are determined by the arguments for the generic
- parameters.273)
+ parameters.<sup><a href="#note273"><b>273)</b></a></sup>
3 Use of the macro invokes a function whose generic parameters have the corresponding
real type determined as follows:
-- First, if any argument for generic parameters has type long double, the type
- 272) Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to
+ <sup><a name="note272" href="#note272"><b>272)</b></a></sup> Like other function-like macros in Standard libraries, each type-generic macro can be suppressed to
make available the corresponding ordinary function.
- 273) If the type of the argument is not compatible with the type of the parameter for the selected function,
+ <sup><a name="note273" href="#note273"><b>273)</b></a></sup> If the type of the argument is not compatible with the type of the parameter for the selected function,
the behavior is undefined.
[<a name="p335" href="#p335">page 335</a>] (<a href="#Contents">Contents</a>)
4 The range and precision of times representable in clock_t and time_t are
implementation-defined. The tm structure shall contain at least the following members,
in any order. The semantics of the members and their normal ranges are expressed in the
- comments.274)
+ comments.<sup><a href="#note274"><b>274)</b></a></sup>
int tm_sec; // seconds after the minute -- [0, 60]
int tm_min; // minutes after the hour -- [0, 59]
int tm_hour; // hours since midnight -- [0, 23]
- 274) The range [0, 60] for tm_sec allows for a positive leap second.
+ <sup><a name="note274" href="#note274"><b>274)</b></a></sup> The range [0, 60] for tm_sec allows for a positive leap second.
[<a name="p338" href="#p338">page 338</a>] (<a href="#Contents">Contents</a>)
only to the program invocation. To determine the time in seconds, the value returned by
the clock function should be divided by the value of the macro CLOCKS_PER_SEC. If
the processor time used is not available or its value cannot be represented, the function
- returns the value (clock_t)(-1).275)
+ returns the value (clock_t)(-1).<sup><a href="#note275"><b>275)</b></a></sup>
<a name="7.23.2.2" href="#7.23.2.2"><b> 7.23.2.2 The difftime function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.23"><time.h></a>
- 275) In order to measure the time spent in a program, the clock function should be called at the start of
+ <sup><a name="note275" href="#note275"><b>275)</b></a></sup> 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.
[<a name="p339" href="#p339">page 339</a>] (<a href="#Contents">Contents</a>)
structure pointed to by timeptr into a calendar time value with the same encoding as
that of the values returned by the time function. The original values of the tm_wday
and tm_yday components of the structure are ignored, and the original values of the
- other components are not restricted to the ranges indicated above.276) On successful
+ other components are not restricted to the ranges indicated above.<sup><a href="#note276"><b>276)</b></a></sup> On successful
completion, the values of the tm_wday and tm_yday components of the structure are
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
- 276) Thus, a positive or zero value for tm_isdst causes the mktime function to presume initially that
+ <sup><a name="note276" href="#note276"><b>276)</b></a></sup> 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.
%u is replaced by the ISO 8601 weekday as a decimal number (1-7), where Monday
is 1. [tm_wday]
%U is replaced by the week number of the year (the first Sunday as the first day of week
- 1) as a decimal number (00-53). [tm_year, tm_wday, tm_yday]
+ <sup><a name="note1" href="#note1"><b>1)</b></a></sup> as a decimal number (00-53). [tm_year, tm_wday, tm_yday]
%V is replaced by the ISO 8601 week number (see below) as a decimal number
(01-53). [tm_year, tm_wday, tm_yday]
%w is replaced by the weekday as a decimal number (0-6), where Sunday is 0.
<a name="7.24" href="#7.24"><b> 7.24 Extended multibyte and wide character utilities <wchar.h></b></a>
<a name="7.24.1" href="#7.24.1"><b> 7.24.1 Introduction</b></a>
1 The header <a href="#7.24"><wchar.h></a> declares four data types, one tag, four macros, and many
- functions.277)
+ functions.<sup><a href="#note277"><b>277)</b></a></sup>
2 The types declared are wchar_t and size_t (both described in <a href="#7.17">7.17</a>);
mbstate_t
which is an object type other than an array type that can hold the conversion state
which is an integer type unchanged by default argument promotions that can hold any
value corresponding to members of the extended character set, as well as at least one
value that does not correspond to any member of the extended character set (see WEOF
- below);278) and
+ below);<sup><a href="#note278"><b>278)</b></a></sup> and
struct tm
which is declared as an incomplete structure type (the contents are described in <a href="#7.23.1">7.23.1</a>).
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
WEOF
which expands to a constant expression of type wint_t whose value does not
- correspond to any member of the extended character set.279) It is accepted (and returned)
+ 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
stream. It is also used as a wide character value that does not correspond to any member
of the extended character set.
-- Functions that perform general wide string manipulation;
-
277) See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
- 278) wchar_t and wint_t can be the same integer type.
- 279) The value of the macro WEOF may differ from that of EOF and need not be negative.
+
<sup><a name="note277" href="#note277"><b>277)</b></a></sup> See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
+ <sup><a name="note278" href="#note278"><b>278)</b></a></sup> wchar_t and wint_t can be the same integer type.
+ <sup><a name="note279" href="#note279"><b>279)</b></a></sup> The value of the macro WEOF may differ from that of EOF and need not be negative.
[<a name="p348" href="#p348">page 348</a>] (<a href="#Contents">Contents</a>)
undefined.
<a name="7.24.2" href="#7.24.2"><b> 7.24.2 Formatted wide character input/output functions</b></a>
1 The formatted wide character input/output functions shall behave as if there is a sequence
- point after the actions associated with each specifier.280)
+ point after the actions associated with each specifier.<sup><a href="#note280"><b>280)</b></a></sup>
<a name="7.24.2.1" href="#7.24.2.1"><b> 7.24.2.1 The fwprintf function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.19"><stdio.h></a>
than the field width, it is padded with spaces (by default) on the left (or right, if the
- 280) The fwprintf functions perform writes to memory for the %n specifier.
+ <sup><a name="note280" href="#note280"><b>280)</b></a></sup> The fwprintf functions perform writes to memory for the %n specifier.
[<a name="p349" href="#p349">page 349</a>] (<a href="#Contents">Contents</a>)
left adjustment flag, described later, has been given) to the field width. The field
width takes the form of an asterisk * (described later) or a nonnegative decimal
- integer.281)
+ integer.<sup><a href="#note281"><b>281)</b></a></sup>
-- An optional precision that gives the minimum number of digits to appear for the d, i,
o, u, x, and X conversions, the number of digits to appear after the decimal-point
wide character for a, A, e, E, f, and F conversions, the maximum number of
this flag is not specified.)
+ The result of a signed conversion always begins with a plus or minus sign. (It
begins with a sign only when a negative value is converted if this flag is not
- specified.)282)
+ specified.)<sup><a href="#note282"><b>282)</b></a></sup>
space 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.
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,
- 281) Note that 0 is taken as a flag, not as the beginning of a field width.
- 282) The results of all floating conversions of a negative zero, and of negative values that round to zero,
+ <sup><a name="note281" href="#note281"><b>281)</b></a></sup> Note that 0 is taken as a flag, not as the beginning of a field width.
+ <sup><a name="note282" href="#note282"><b>282)</b></a></sup> The results of all floating conversions of a negative zero, and of negative values that round to zero,
include a minus sign.
[<a name="p350" href="#p350">page 350</a>] (<a href="#Contents">Contents</a>)
specifier produces INF, INFINITY, or NAN instead of inf, infinity, or
[<a name="p352" href="#p352">page 352</a>] (<a href="#Contents">Contents</a>)
- nan, respectively.283)
+ nan, respectively.<sup><a href="#note283"><b>283)</b></a></sup>
e,E 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
a,A 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 character284) and the
+ 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
-283) When applied to infinite and NaN values, the -, +, and space flag wide characters have their usual
+<sup><a name="note283" href="#note283"><b>283)</b></a></sup> When applied to infinite and NaN values, the -, +, and space flag wide characters have their usual
meaning; the # and 0 flag wide characters have no effect.
-284) Binary implementations can choose the hexadecimal digit to the left of the decimal-point wide
+<sup><a name="note284" href="#note284"><b>284)</b></a></sup> 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.
[<a name="p353" href="#p353">page 353</a>] (<a href="#Contents">Contents</a>)
for an exact representation of the value; if the precision is missing and
FLT_RADIX is not a power of 2, then the precision is sufficient to
- distinguish285) values of type double, except that trailing zeros may be
+ distinguish<sup><a href="#note285"><b>285)</b></a></sup> values of type double, except that trailing zeros may be
omitted; if the precision is zero and the # flag is not specified, no decimal-
point wide character appears. The letters abcdef are used for a conversion
and the letters ABCDEF for A conversion. The A conversion specifier
p 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-
-285) The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
+<sup><a name="note285" href="#note285"><b>285)</b></a></sup> The precision p is sufficient to distinguish values of the source type if 16 p-1 > b n where b is
FLT_RADIX and n is the number of base-b digits in the significand of the source type. A smaller p
might suffice depending on the implementation's scheme for determining the digit to the left of the
decimal-point wide character.
behavior is undefined.
% A % wide character is written. No argument is converted. The complete
conversion specification shall be %%.
-9 If a conversion specification is invalid, the behavior is undefined.286) If any argument is
+9 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.
10 In no case does a nonexistent or small field width cause truncation of a field; if the result
in hexadecimal floating style with the given precision, with the extra stipulation that the
error should have a correct sign for the current rounding direction.
13 For e, E, f, F, g, and G conversions, if the number of significant decimal digits is at most
- DECIMAL_DIG, then the result should be correctly rounded.287) If the number of
+ DECIMAL_DIG, then the result should be correctly rounded.<sup><a href="#note287"><b>287)</b></a></sup> If the number of
significant decimal digits is more than DECIMAL_DIG but the source value is exactly
representable with DECIMAL_DIG digits, then the result should be an exact
representation with trailing zeros. Otherwise, the source value is bounded by two
14 The fwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-
286) See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
- 287) For binary-to-decimal conversion, the result format's values are the numbers representable with the
+
<sup><a name="note286" href="#note286"><b>286)</b></a></sup> See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
+ <sup><a name="note287" href="#note287"><b>287)</b></a></sup> For binary-to-decimal conversion, the result format's values are the numbers representable with the
given format specifier. The number of significant digits is determined by the format specifier, and in
the case of fixed-point conversion by the source value as well.
described below for each specifier. A conversion specification is executed in the
following steps:
8 Input white-space wide characters (as specified by the iswspace function) are skipped,
- unless the specification includes a [, c, or n specifier.288)
+ unless the specification includes a [, c, or n specifier.<sup><a href="#note288"><b>288)</b></a></sup>
9 An input item is read from the stream, unless the specification includes an n specifier. An
input item is defined as the longest sequence of input wide characters which does not
exceed any specified field width and which is, or is a prefix of, a matching input
- sequence.289) The first wide character, if any, after the input item remains unread. If the
+ sequence.<sup><a href="#note289"><b>289)</b></a></sup> The first wide character, if any, after the input item remains unread. If the
length of the input item is zero, the execution of the directive fails; this condition is a
matching failure unless end-of-file, an encoding error, or a read error prevented input
from the stream, in which case it is an input failure.
following the format argument that has not already received a conversion result. If this
- 288) These white-space wide characters are not counted against a specified field width.
- 289) fwscanf pushes back at most one input wide character onto the input stream. Therefore, some
+ <sup><a name="note288" href="#note288"><b>288)</b></a></sup> These white-space wide characters are not counted against a specified field width.
+ <sup><a name="note289" href="#note289"><b>289)</b></a></sup> fwscanf pushes back at most one input wide character onto the input stream. Therefore, some
sequences that are acceptable to wcstod, wcstol, etc., are unacceptable to fwscanf.
[<a name="p357" href="#p357">page 357</a>] (<a href="#Contents">Contents</a>)
undefined.
% Matches a single % wide character; no conversion or assignment occurs. The
complete conversion specification shall be %%.
-13 If a conversion specification is invalid, the behavior is undefined.290)
+13 If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note290"><b>290)</b></a></sup>
14 The conversion specifiers A, E, F, G, and X are also valid and behave the same as,
respectively, a, e, f, g, and x.
15 Trailing white space (including new-line wide characters) is left unread unless matched
56.0. The next wide character read from the input stream will be a.
-
290) See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
+
<sup><a name="note290" href="#note290"><b>290)</b></a></sup> See ''future library directions'' (<a href="#7.26.12">7.26.12</a>).
[<a name="p361" href="#p361">page 361</a>] (<a href="#Contents">Contents</a>)
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.291)
+ va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<b> Returns</b>
3 The vfwprintf function returns the number of wide characters transmitted, or a
negative value if an output or encoding error occurred.
- 291) As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
+ <sup><a name="note291" href="#note291"><b>291)</b></a></sup> As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
invoke the va_arg macro, the value of arg after the return is indeterminate.
[<a name="p363" href="#p363">page 363</a>] (<a href="#Contents">Contents</a>)
the fgetwc function returns the next wide character from the input stream pointed to by
stream. If a read error occurs, the error indicator for the stream is set and the fgetwc
function returns WEOF. If an encoding error occurs (including too few bytes), the value of
- the macro EILSEQ is stored in errno and the fgetwc function returns WEOF.292)
+ the macro EILSEQ is stored in errno and the fgetwc function returns WEOF.<sup><a href="#note292"><b>292)</b></a></sup>
<a name="7.24.3.2" href="#7.24.3.2"><b> 7.24.3.2 The fgetws function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.19"><stdio.h></a>
specified by n from the stream pointed to by stream into the array pointed to by s. No
- 292) An end-of-file and a read error can be distinguished by use of the feof and ferror functions.
+ <sup><a name="note292" href="#note292"><b>292)</b></a></sup> 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.
[<a name="p367" href="#p367">page 367</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
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.293)
+ 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.
<b> Returns</b>
3 The fwide function returns a value greater than zero if, after the call, the stream has
- 293) If the orientation of the stream has already been determined, fwide does not change it.
+ <sup><a name="note293" href="#note293"><b>293)</b></a></sup> If the orientation of the stream has already been determined, fwide does not change it.
[<a name="p369" href="#p369">page 369</a>] (<a href="#Contents">Contents</a>)
floating point number, or if a binary exponent part does not appear in a hexadecimal
floating point number, an exponent part of the appropriate type with value zero is
assumed to follow the last digit in the string. If the subject sequence begins with a minus
- sign, the sequence is interpreted as negated.294) A wide character sequence INF or
+ 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
in the return type, else like a subject sequence part that does not have the expected form;
- the meaning of the n-wchar sequences is implementation-defined.295) A pointer to the
+ 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
not a null pointer.
5 If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
- 294) It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
+ <sup><a name="note294" href="#note294"><b>294)</b></a></sup> 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,
the functions honor the sign of zero if floating-point arithmetic supports signed zeros.
- 295) An implementation may use the n-wchar sequence to determine extra information to be represented in
+ <sup><a name="note295" href="#note295"><b>295)</b></a></sup> An implementation may use the n-wchar sequence to determine extra information to be represented in
the NaN's significand.
[<a name="p373" href="#p373">page 373</a>] (<a href="#Contents">Contents</a>)
The result should be one of the (equal or adjacent) values that would be obtained by
correctly rounding L and U according to the current rounding direction, with the extra
stipulation that the error with respect to D should have a correct sign for the current
- rounding direction.296)
+ rounding direction.<sup><a href="#note296"><b>296)</b></a></sup>
<b> Returns</b>
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
-
296) DECIMAL_DIG, defined in <a href="#7.7"><float.h></a>, should be sufficiently large that L and U will usually round
+
<sup><a name="note296" href="#note296"><b>296)</b></a></sup> DECIMAL_DIG, defined in <a href="#7.7"><float.h></a>, should be sufficiently large that L and U will usually round
to the same internal floating value, but if not will round to adjacent values.
[<a name="p374" href="#p374">page 374</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
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
- s1.297)
+ s1.<sup><a href="#note297"><b>297)</b></a></sup>
3 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.
- 297) Thus, if there is no null wide character in the first n wide characters of the array pointed to by s2, the
+ <sup><a name="note297" href="#note297"><b>297)</b></a></sup> 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.
[<a name="p377" href="#p377">page 377</a>] (<a href="#Contents">Contents</a>)
the wide string pointed to by s1. The initial wide character of s2 overwrites the null
wide character at the end of s1. A terminating null wide character is always appended to
- the result.298)
+ the result.<sup><a href="#note298"><b>298)</b></a></sup>
<b> Returns</b>
3 The wcsncat function returns the value of s1.
<a name="7.24.4.4" href="#7.24.4.4"><b> 7.24.4.4 Wide string comparison functions</b></a>
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
- 298) Thus, the maximum number of wide characters that can end up in the array pointed to by s1 is
+ <sup><a name="note298" href="#note298"><b>298)</b></a></sup> Thus, the maximum number of wide characters that can end up in the array pointed to by s1 is
wcslen(s1)+n+1.
[<a name="p379" href="#p379">page 379</a>] (<a href="#Contents">Contents</a>)
been altered by any of the functions described in this subclause, and is then used with a
different multibyte character sequence, or in the other conversion direction, or with a
different LC_CTYPE category setting than on earlier function calls, the behavior is
- undefined.299)
+ undefined.<sup><a href="#note299"><b>299)</b></a></sup>
4 On entry, each function takes the described conversion state (either internal or pointed to
by an argument) as current. The conversion state described by the pointed-to object is
altered as needed to track the shift state, and the position within a multibyte character, for
- 299) Thus, a particular mbstate_t object can be used, for example, with both the mbrtowc and
+ <sup><a name="note299" href="#note299"><b>299)</b></a></sup> 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.
of bytes that complete the multibyte character.
(size_t)(-2) 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).300)
+ stored).<sup><a href="#note300"><b>300)</b></a></sup>
(size_t)(-1) 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.
- 300) When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a
+ <sup><a name="note300" href="#note300"><b>300)</b></a></sup> 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).
[<a name="p389" href="#p389">page 389</a>] (<a href="#Contents">Contents</a>)
continues up to and including a terminating null character, which is also stored.
Conversion stops earlier in two cases: when a sequence of bytes is encountered that does
not form a valid multibyte character, or (if dst is not a null pointer) when len wide
- characters have been stored into the array pointed to by dst.301) Each conversion takes
+ characters have been stored into the array pointed to by dst.<sup><a href="#note301"><b>301)</b></a></sup> Each conversion takes
place as if by a call to the mbrtowc function.
3 If dst is not a null pointer, the pointer object pointed to by src is assigned either a null
pointer (if conversion stopped due to reaching a terminating null character) or the address
- 301) Thus, the value of len is ignored if dst is a null pointer.
+ <sup><a name="note301" href="#note301"><b>301)</b></a></sup> Thus, the value of len is ignored if dst is a null pointer.
[<a name="p391" href="#p391">page 391</a>] (<a href="#Contents">Contents</a>)
not correspond to a valid multibyte character, or (if dst is not a null pointer) when the
next multibyte character would exceed the limit of len total bytes to be stored into the
array pointed to by dst. Each conversion takes place as if by a call to the wcrtomb
- function.302)
+ function.<sup><a href="#note302"><b>302)</b></a></sup>
3 If dst is not a null pointer, the pointer object pointed to by src is assigned either a null
pointer (if conversion stopped due to reaching a terminating null wide character) or the
address just past the last wide character converted (if any). If conversion stopped due to
- 302) If conversion stops because a terminating null wide character has been reached, the bytes stored
+ <sup><a name="note302" href="#note302"><b>302)</b></a></sup> 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.
[<a name="p392" href="#p392">page 392</a>] (<a href="#Contents">Contents</a>)
<a name="7.25" href="#7.25"><b> 7.25 Wide character classification and mapping utilities <wctype.h></b></a>
<a name="7.25.1" href="#7.25.1"><b> 7.25.1 Introduction</b></a>
-1 The header <a href="#7.25"><wctype.h></a> declares three data types, one macro, and many functions.303)
+1 The header <a href="#7.25"><wctype.h></a> declares three data types, one macro, and many functions.<sup><a href="#note303"><b>303)</b></a></sup>
2 The types declared are
wint_t
described in <a href="#7.24.1">7.24.1</a>;
-
303) See ''future library directions'' (<a href="#7.26.13">7.26.13</a>).
+
<sup><a name="note303" href="#note303"><b>303)</b></a></sup> See ''future library directions'' (<a href="#7.26.13">7.26.13</a>).
[<a name="p393" href="#p393">page 393</a>] (<a href="#Contents">Contents</a>)
if by a call to the wctob function) to a single-byte character for which the corresponding
character classification function from <a href="#7.4.1">7.4.1</a> returns true, except that the iswgraph and
iswpunct functions may differ with respect to wide characters other than L' ' that are
- both printing and white-space wide characters.304)
+ both printing and white-space wide characters.<sup><a href="#note304"><b>304)</b></a></sup>
Forward references: the wctob function (<a href="#7.24.6.1.2">7.24.6.1.2</a>).
<a name="7.25.2.1.1" href="#7.25.2.1.1"><b> 7.25.2.1.1 The iswalnum function</b></a>
<b> Synopsis</b>
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
- 304) For example, if the expression isalpha(wctob(wc)) evaluates to true, then the call
+ <sup><a name="note304" href="#note304"><b>304)</b></a></sup> For example, if the expression isalpha(wctob(wc)) evaluates to true, then the call
iswalpha(wc) also returns true. But, if the expression isgraph(wctob(wc)) evaluates to true
(which cannot occur for wc == L' ' of course), then either iswgraph(wc) or iswprint(wc)
&& iswspace(wc) is true, but not both.
[<a name="p394" href="#p394">page 394</a>] (<a href="#Contents">Contents</a>)
wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace
- is true.305)
+ is true.<sup><a href="#note305"><b>305)</b></a></sup>
<a name="7.25.2.1.3" href="#7.25.2.1.3"><b> 7.25.2.1.3 The iswblank function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.25"><wctype.h></a>
- 305) The functions iswlower and iswupper test true or false separately for each of these additional
+ <sup><a name="note305" href="#note305"><b>305)</b></a></sup> The functions iswlower and iswupper test true or false separately for each of these additional
wide characters; all four combinations are possible.
[<a name="p395" href="#p395">page 395</a>] (<a href="#Contents">Contents</a>)
<b> Description</b>
2 The iswgraph function tests for any wide character for which iswprint is true and
- iswspace is false.306)
+ iswspace is false.<sup><a href="#note306"><b>306)</b></a></sup>
<a name="7.25.2.1.7" href="#7.25.2.1.7"><b> 7.25.2.1.7 The iswlower function</b></a>
<b> Synopsis</b>
1 #include <a href="#7.25"><wctype.h></a>
- 306) Note that the behavior of the iswgraph and iswpunct functions may differ from their
+ <sup><a name="note306" href="#note306"><b>306)</b></a></sup> 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 ' '.
1 The C floating types match the IEC 60559 formats as follows:
-- The float type matches the IEC 60559 single format.
-- The double type matches the IEC 60559 double format.
- -- The long double type matches an IEC 60559 extended format,307) else a
+ -- The long double type matches an IEC 60559 extended format,<sup><a href="#note307"><b>307)</b></a></sup> else a
non-IEC 60559 extended format, else the IEC 60559 double format.
Any non-IEC 60559 extended format used for the long double type shall have more
- precision than IEC 60559 double and at least the range of IEC 60559 double.308)
+ 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
2 The long double type should match an IEC 60559 extended format.
- 307) ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit
+ <sup><a name="note307" href="#note307"><b>307)</b></a></sup> ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit
and quadruple 128-bit IEC 60559 formats.
- 308) A non-IEC 60559 long double type is required to provide infinity and NaNs, as its values include
+ <sup><a name="note308" href="#note308"><b>308)</b></a></sup> A non-IEC 60559 long double type is required to provide infinity and NaNs, as its values include
all double values.
[<a name="p444" href="#p444">page 444</a>] (<a href="#Contents">Contents</a>)
<a name="F.2.1" href="#F.2.1"><b> F.2.1 Infinities, signed zeros, and NaNs</b></a>
-1 This specification does not define the behavior of signaling NaNs.309) It generally uses
+1 This specification does not define the behavior of signaling NaNs.<sup><a href="#note309"><b>309)</b></a></sup> It generally uses
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.
<a name="F.3" href="#F.3"><b> F.3 Operators and functions</b></a>
strtold function in <a href="#7.20"><stdlib.h></a> provides the conv function recommended in the
Appendix to ANSI/IEEE 854.
- 309) Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are
+ <sup><a name="note309" href="#note309"><b>309)</b></a></sup> Since NaNs created by IEC 60559 operations are always quiet, quiet NaNs (along with infinities) are
sufficient for closure of the arithmetic.
[<a name="p445" href="#p445">page 445</a>] (<a href="#Contents">Contents</a>)
the range of the integer type, then the ''invalid'' floating-point exception is raised and the
resulting value is unspecified. Whether conversion of non-integer floating values whose
integral part is within the range of the integer type raises the ''inexact'' floating-point
- exception is unspecified.310)
+ exception is unspecified.<sup><a href="#note310"><b>310)</b></a></sup>
<a name="F.5" href="#F.5"><b> F.5 Binary-decimal conversion</b></a>
1 Conversion from the widest supported IEC 60559 format to decimal with
- DECIMAL_DIG digits and back is the identity function.311)
+ DECIMAL_DIG digits and back is the identity function.<sup><a href="#note311"><b>311)</b></a></sup>
2 Conversions involving IEC 60559 formats follow all pertinent recommended practice. In
particular, conversion between any supported IEC 60559 format and decimal with
DECIMAL_DIG or fewer significant digits is correctly rounded (honoring the current
- 310) ANSI/IEEE 854, but not IEC 60559 (ANSI/IEEE 754), directly specifies that floating-to-integer
+ <sup><a name="note310" href="#note310"><b>310)</b></a></sup> 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
the ''inexact'' floating-point exception. See rint, lrint, llrint, and nearbyint in
<a href="#7.12"><math.h></a>.
- 311) If the minimum-width IEC 60559 extended format (64 bits of precision) is supported,
+ <sup><a name="note311" href="#note311"><b>311)</b></a></sup> If the minimum-width IEC 60559 extended format (64 bits of precision) is supported,
DECIMAL_DIG shall be at least 21. If IEC 60559 double (53 bits of precision) is the widest
IEC 60559 format supported, then DECIMAL_DIG shall be at least 17. (By contrast, LDBL_DIG and
DBL_DIG are 18 and 15, respectively, for these formats.)
1 The floating-point environment defined in <a href="#7.6"><fenv.h></a> includes the IEC 60559 floating-
point exception status flags and directed-rounding control modes. It includes also
IEC 60559 dynamic rounding precision and trap enablement modes, if the
- implementation supports them.312)
+ implementation supports them.<sup><a href="#note312"><b>312)</b></a></sup>
<a name="F.7.1" href="#F.7.1"><b> F.7.1 Environment management</b></a>
1 IEC 60559 requires that floating-point operations implicitly raise floating-point exception
status flags, and that rounding control modes can be set explicitly to affect result values of
floating-point operations. When the state for the FENV_ACCESS pragma (defined in
<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.313)
+ which respect sequence points.<sup><a href="#note313"><b>313)</b></a></sup>
<a name="F.7.2" href="#F.7.2"><b> F.7.2 Translation</b></a>
1 During translation the IEC 60559 default modes are in effect:
-- The rounding direction mode is rounding to nearest.
- 312) This specification does not require dynamic rounding precision nor trap enablement modes.
- 313) If the state for the FENV_ACCESS pragma is ''off'', the implementation is free to assume the floating-
+ <sup><a name="note312" href="#note312"><b>312)</b></a></sup> This specification does not require dynamic rounding precision nor trap enablement modes.
+ <sup><a name="note313" href="#note313"><b>313)</b></a></sup> 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>).
[<a name="p448" href="#p448">page 448</a>] (<a href="#Contents">Contents</a>)
- floating-point exception, other than ''inexact'';314) the implementation should then
+ 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.
<a name="F.7.3" href="#F.7.3"><b> F.7.3 Execution</b></a>
1 At program startup the floating-point environment is initialized as prescribed by
object that has static storage duration, is evaluated (as if) during execution; thus, it is
affected by any operative floating-point control modes and raises floating-point
exceptions as required by IEC 60559 (provided the state for the FENV_ACCESS pragma
- is ''on'').315)
+ is ''on'').<sup><a href="#note315"><b>315)</b></a></sup>
2 EXAMPLE
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
point exceptions. On the other hand, for the three automatic initializations the invalid division occurs at
- 314) As floating constants are converted to appropriate internal representations at translation time, their
+ <sup><a name="note314" href="#note314"><b>314)</b></a></sup> As floating constants are converted to appropriate internal representations at translation time, their
conversion is subject to default rounding modes and raises no execution-time floating-point exceptions
(even where the state of the FENV_ACCESS pragma is ''on''). Library functions, for example
strtod, provide execution-time conversion of numeric strings.
- 315) Where the state for the FENV_ACCESS pragma is ''on'', results of inexact expressions like 1.0/3.0
+ <sup><a name="note315" href="#note315"><b>315)</b></a></sup> 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
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
of x and y entail execution-time conversion; however, in some expression evaluation methods, the
- conversions is not to a narrower format, in which case no floating-point exception is raised.316) The
+ conversions is not to a narrower format, in which case no floating-point exception is raised.<sup><a href="#note316"><b>316)</b></a></sup> The
automatic initialization of z entails execution-time conversion, but not to a narrower format, so no floating-
point exception is raised. Note that the conversions of the floating constants 1.1e75 and 1.1e75f to
their internal representations occur at translation time in all cases.
- 316) Use of float_t and double_t variables increases the likelihood of translation-time computation.
+ <sup><a name="note316" href="#note316"><b>316)</b></a></sup> Use of float_t and double_t variables increases the likelihood of translation-time computation.
For example, the automatic initialization
double_t x = 1.1e75;
could be done at translation time, regardless of the expression evaluation method.
transformations can be made on IEC 60559 machines
and others that round perfectly.
1 * x and x / 1 (->) x The expressions 1 * x, x / 1, and x are equivalent
- (on IEC 60559 machines, among others).317)
+ (on IEC 60559 machines, among others).<sup><a href="#note317"><b>317)</b></a></sup>
x / x (->) 1.0 The expressions x / x and 1.0 are not equivalent if x
can be zero, infinite, or NaN.
x - y (<->) x + (-y) The expressions x - y, x + (-y), and (-y) + x
are equivalent (on IEC 60559 machines, among others).
x - y (<->) -(y - x) The expressions x - y and -(y - x) are not
equivalent because 1 - 1 is +0 but -(1 - 1) is -0 (in the
- default rounding direction).318)
+ default rounding direction).<sup><a href="#note318"><b>318)</b></a></sup>
x - x (->) 0.0 The expressions x - x and 0.0 are not equivalent if
x is a NaN or infinite.
0 * x (->) 0.0 The expressions 0 * x and 0.0 are not equivalent if
implementation can replace x - 0 by x, even if x
- 317) Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
+ <sup><a name="note317" href="#note317"><b>317)</b></a></sup> Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
other transformations that remove arithmetic operators.
- 318) IEC 60559 prescribes a signed zero to preserve mathematical identities across certain discontinuities.
+ <sup><a name="note318" href="#note318"><b>318)</b></a></sup> IEC 60559 prescribes a signed zero to preserve mathematical identities across certain discontinuities.
Examples include:
1/(1/ (+-) (inf)) is (+-) (inf)
and
and <a href="#F.7.5">F.7.5</a>.) An operation on constants that raises no floating-point exception can be
folded during translation, except, if the state of the FENV_ACCESS pragma is ''on'', a
further check is required to assure that changing the rounding direction to downward does
- not alter the sign of the result,319) and implementations that support dynamic rounding
+ not alter the sign of the result,<sup><a href="#note319"><b>319)</b></a></sup> and implementations that support dynamic rounding
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.
<a name="F.9" href="#F.9"><b> F.9 Mathematics <math.h></b></a>
rounding direction, a maximal-magnitude finite number -- is returned in lieu of a value
- 319) 0 - 0 yields -0 instead of +0 just when the rounding direction is downward.
+ <sup><a name="note319" href="#note319"><b>319)</b></a></sup> 0 - 0 yields -0 instead of +0 just when the rounding direction is downward.
[<a name="p454" href="#p454">page 454</a>] (<a href="#Contents">Contents</a>)
whose magnitude is too large.
7 The ''underflow'' floating-point exception is raised whenever a result is tiny (essentially
- subnormal or zero) and suffers loss of accuracy.320)
+ subnormal or zero) and suffers loss of accuracy.<sup><a href="#note320"><b>320)</b></a></sup>
8 Whether or when library functions raise the ''inexact'' floating-point exception is
unspecified, unless explicitly specified otherwise.
9 Whether or when library functions raise an undeserved ''underflow'' floating-point
- exception is unspecified.
321) Otherwise, as implied by <a href="#F.7.6">F.7.6</a>, the <a href="#7.12"><math.h></a> functions do
+ exception is unspecified.
<sup><a href="#note321"><b>321)</b></a></sup> Otherwise, as implied by <a href="#F.7.6">F.7.6</a>, the <a href="#7.12"><math.h></a> functions do
not raise spurious floating-point exceptions (detectable by the user), other than the
''inexact'' floating-point exception.
10 Whether the functions honor the rounding direction mode is implementation-defined,
- 320) IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on
+ <sup><a name="note320" href="#note320"><b>320)</b></a></sup> IEC 60559 allows different definitions of underflow. They all result in the same values, but differ on
when the floating-point exception is raised.
- 321) It is intended that undeserved ''underflow'' and ''inexact'' floating-point exceptions are raised only if
+ <sup><a name="note321" href="#note321"><b>321)</b></a></sup> It is intended that undeserved ''underflow'' and ''inexact'' floating-point exceptions are raised only if
avoiding them would be too costly.
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1 -- atan((+-)0) returns (+-)0.
-- atan((+-)(inf)) returns (+-)pi /2.
<a name="F.9.1.4" href="#F.9.1.4"><b> F.9.1.4 The atan2 functions</b></a>
-1 -- atan2((+-)0, -0) returns (+-)pi .322)
+1 -- atan2((+-)0, -0) returns (+-)pi .<sup><a href="#note322"><b>322)</b></a></sup>
-- atan2((+-)0, +0) returns (+-)0.
-- atan2((+-)0, x) returns (+-)pi for x < 0.
-- atan2((+-)0, x) returns (+-)0 for x > 0.
- 322) atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise
+ <sup><a name="note322" href="#note322"><b>322)</b></a></sup> atan2(0, 0) does not raise the ''invalid'' floating-point exception, nor does atan2( y , 0) raise
the ''divide-by-zero'' floating-point exception.
[<a name="p456" href="#p456">page 456</a>] (<a href="#Contents">Contents</a>)
<a name="F.9.9.2" href="#F.9.9.2"><b> F.9.9.2 The fmax functions</b></a>
1 If just one argument is a NaN, the fmax functions return the other argument (if both
arguments are NaNs, the functions return a NaN).
-2 The body of the fmax function might be323)
+2 The body of the fmax function might be<sup><a href="#note323"><b>323)</b></a></sup>
{ return (isgreaterequal(x, y) ||
isnan(y)) ? x : y; }
<a name="F.9.9.3" href="#F.9.9.3"><b> F.9.9.3 The fmin functions</b></a>
- 323) Ideally, fmax would be sensitive to the sign of zero, for example fmax(-0.0, +0.0) would
+ <sup><a name="note323" href="#note323"><b>323)</b></a></sup> 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.
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1 Conversions among imaginary types follow rules analogous to those for real floating
types.
<a name="G.4.2" href="#G.4.2"><b> G.4.2 Real and imaginary</b></a>
-1 When a value of imaginary type is converted to a real type other than _Bool,324) the
+1 When a value of imaginary type is converted to a real type other than _Bool,<sup><a href="#note324"><b>324)</b></a></sup> the
result is a positive zero.
2 When a value of real type is converted to an imaginary type, the result is a positive
imaginary zero.
-
324) See <a href="#6.3.1.2">6.3.1.2</a>.
+
<sup><a name="note324" href="#note324"><b>324)</b></a></sup> See <a href="#6.3.1.2">6.3.1.2</a>.
[<a name="p468" href="#p468">page 468</a>] (<a href="#Contents">Contents</a>)
x + iy (x/u) + i(y/u) (y/v) + i(-x/v)
4 The * and / operators satisfy the following infinity properties for all real, imaginary, and
- complex operands:325)
+ complex operands:<sup><a href="#note325"><b>325)</b></a></sup>
-- if one operand is an infinity and the other operand is a nonzero finite number or an
infinity, then the result of the * operator is an infinity;
-- if the first operand is an infinity and the second operand is a finite number, then the
- 325) These properties are already implied for those cases covered in the tables, but are required for all cases
+ <sup><a name="note325" href="#note325"><b>325)</b></a></sup> 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'').
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4 Since complex and imaginary values are composed of real values, each function may be
regarded as computing real values from real values. Except as noted, the functions treat
real infinities, NaNs, signed zeros, subnormals, and the floating-point exception flags in a
- manner consistent with the specifications for real functions in F.9.326)
+ manner consistent with the specifications for real functions in F.9.<sup><a href="#note326"><b>326)</b></a></sup>
5 The functions cimag, conj, cproj, and creal are fully specified for all
implementations, including IEC 60559 ones, in <a href="#7.3.9">7.3.9</a>. These functions raise no floating-
point exceptions.
-
326) 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
+
<sup><a name="note326" href="#note326"><b>326)</b></a></sup> 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.
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<a name="G.6.4" href="#G.6.4"><b> G.6.4 Power and absolute-value functions</b></a>
<a name="G.6.4.1" href="#G.6.4.1"><b> G.6.4.1 The cpow functions</b></a>
1 The cpow functions raise floating-point exceptions if appropriate for the calculation of
- the parts of the result, and may raise spurious exceptions.327)
+ the parts of the result, and may raise spurious exceptions.<sup><a href="#note327"><b>327)</b></a></sup>
<a name="G.6.4.2" href="#G.6.4.2"><b> G.6.4.2 The csqrt functions</b></a>
1 -- csqrt(conj(z)) = conj(csqrt(z)).
-- csqrt((+-)0 + i0) returns +0 + i0.
- 327) This allows cpow( z , c ) to be implemented as cexp(c clog( z )) without precluding
+ <sup><a name="note327" href="#note327"><b>327)</b></a></sup> This allows cpow( z , c ) to be implemented as cexp(c clog( z )) without precluding
implementations that treat special cases more carefully.
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projects / c-standard / blobdiff